chocolates makesSmilESSSSS ;)

2007-08-04T10:04:00.000-07:00

Detection of fd born pathogens

The Enzyme-Linked ImmunoSorbent Assay, or ELISA, is a biochemical technique used mainly in immunology to detect the presence of an antibody or an antigen in a sample. The ELISA has been used as a diagnostic tool in medicine and plant pathology, as well as a quality control check in various industries. Performing an ELISA involves at least one antibody with specificity for a particular antigen. The sample with an unknown amount of antigen is immobilized on a solid support (usually a polystyrene microtiter plate) either non-specifically (via adsorption to the surface) or specifically (via capture by another antibody specific to the same antigen, in a "sandwich" ELISA). After the antigen is immobilized the detection antibody is added, forming a complex with the antigen. The detection antibody can be covalently linked to an enzyme, or can itself be detected by a secondary antibody which is linked to an enzyme through bioconjugation. Between each step the plate is typically washed with a mild detergent solution to remove any proteins or antibodies that are not specifically bound. After the final wash step the plate is developed by adding an enzymatic substrate to produce a visible signal, which indicates the quantity of antigen in the sample. Older ELISAs utilize chromogenic substrates, though newer assays employ fluorogenic substrates with much higher sensitivity. In simple terms, an unknown amount of antigen in a sample is immobilized on a surface. One then washes a particular antibody over the surface. This antibody is linked to an enzyme that visibly reacts when activated, say by light hitting it in the case of a fluorescent enzyme; the brightness of the fluorescence would then tell you how much antigen is in your sample.
Applications
Because the ELISA can be performed to evaluate either the presence of antigen or the presence of antibody in a sample, it is a useful tool both for determining serum antibody concentrations (such as with the HIV test [1] or West Nile Virus) and also for detecting the presence of antigen. It has also found applications in the food industry in detecting potential food allergens such as milk, peanuts, walnuts, almonds, and eggs.[2]
Methods
The steps of the general, "indirect," ELISA for determining serum antibody concentrations are:
Apply a sample of known antigen to a surface, often the well of a microtiter plate. The antigen is fixed to the surface to render it immobile. Simple adsorption of the protein to the plastic surface is usually sufficient. These samples of known antigen concentrations will constitute a standard curve used to calculate antigen concentrations of unknown samples. Note that the antigen itself may be an antibody.
The plate wells or other surface are then coated with serum samples of unknown antigen concentration, diluted into the same buffer used for the antigen standards. Since antigen immobilization in this step is due to non-specific adsorption, it is important for the total protein concentration to be similar to that of the antigen standards.
A concentrated solution of non-interacting protein, such as Bovine Serum Albumin (BSA) or casein, is added to all plate wells. This step is known as blocking, because the serum proteins block non-specific adsorption of other proteins to the plate.
The plate is washed, and a detection antibody specific to the antigen of interest is applied to all plate wells. This antibody will only bind to immobilized antigen on the well surface, not to other serum proteins or the blocking proteins.
The plate is washed to remove any unbound detection antibody. After this wash, only the antibody-antigen complexes remain attached to the well.
Secondary antibodies, which will bind to any remaining detection antibodies, are added to the wells. These secondary antibodies are conjugated to the substrate-specific enzyme. This step may be skipped if the detection antibody is conjugated to an enzyme.
Wash the plate, so that excess unbound enzyme-antibody conjugates are removed.
Apply a substrate which is converted by the enzyme to elicit a chromogenic or fluorogenic signal.
View/quantify the result using a spectrophotometer, spectrofluorometer, or other optical device.
The enzyme acts as an amplifier; even if only few enzyme-linked antibodies remain bound, the enzyme molecules will produce many signal molecules. A major disadvantage of the indirect ELISA is that the method of antigen immobilization is non-specific; any proteins in the sample will stick to the microtiter plate well, so small concentrations of analyte in serum must compete with other serum proteins when binding to the well surface. The sandwich ELISA provides a solution to this problem.
ELISA may be run in a qualitative or quantitative format. Qualitative results provide a simple positive or negative result for a sample. The cutoff between positive and negative is determined by the analyst and may be statistical. Two or three times the standard deviation is often used to distinguish positive and negative samples. In quantitative ELISA, the optical density or fluorescent units of the sample is interpolated into a standard curve, which is typically a serial dilution of the target

A sandwich ELISA. (1) Plate is coated with a capture antibody; (2) sample is added, and any antigen present binds to capture antibody; (3) detecting antibody is added, and binds to antigen; (4) enzyme-linked secondary antibody is added, and binds to detecting antibody; (5) substrate is added, and is converted by enzyme to detectable form.
A less-common variant of this technique, called "sandwich" ELISA, is used to detect sample antigen. The steps are as follows:
Prepare a surface to which a known quantity of capture antibody is bound.
Block any non specific binding sites on the surface.
Apply the antigen-containing sample to the plate.
Wash the plate, so that unbound antigen is removed.
Apply a detection antibody, with the same antigen specificity as the immobilized capture antibody.
Apply enzyme-linked secondary antibodies which are specific to the detection antibodies.
Wash the plate, so that the unbound antibody-enzyme conjugates are removed.
Apply a chemical which is converted by the enzyme into a color or fluorescent signal.
Measure the absorbance or fluorescence of the plate wells to determine the presence and quantity of antigen.
The image to the right includes the use of a secondary antibody conjugated to an enzyme, though technically this is not necessary if the detection antibody is conjugated to an enzyme. However, use of a secondary-antibody conjugate avoids the expensive process of creating enzyme-linked antibodies for every antigen one might want to detect. By using an enzyme-linked antibody that binds the Fc region of other antibodies, this same enzyme-linked antibody can be used in a variety of situations. The major advantage of a sandwich ELISA is the ability to use crude or impure samples and still selectively bind any antigen that may be present. Without the first layer of "capture" antibody, any proteins in the sample (including serum proteins) may competitively adsorb to the plate surface, lowering the quantity of antigen immobilized.

Competitive ELISA
A third use of ELISA is through competitive binding. The steps for this ELISA are somewhat different than the first two examples:
Unlabeled antibody is incubated in the presence of its antigen.
These bound antibody/antigen complexes are then added to an antigen coated well.
The plate is washed, so that unbound antibody is removed. (The more antigen in the sample, the less antibody will be able to bind to the antigen in the well, hence "competition.")
The secondary antibody, specific to the primary antibody is added. This second antibody is coupled to the enzyme.
A substrate is added, and remaining enzymes elicit a chromogenic or fluorescent signal.
For competitive ELISA, the higher the original antigen concentration, the weaker the eventual signal.
http://en.wikipedia.org/wiki/Enzyme-linked_immunosorbent_assay

2007-08-04T09:51:00.000-07:00

Detection of hazards:
Toxins detectation

Chromatography

HPLC
- High Performance Liquid Chromatography
The Principles of High Pressure (Performance) Chromatography
Chromatography is the term used to describe a separation technique in which a mobile phase carrying a mixture is caused to move in contact with a selectively absorbent stationary phase. Different components of the sample are carried forward at different rates by the moving liquid phase, due to their differing interactions with the stationary and mobile phases. There are a number of different kinds of chromatography, which differ in the mobile and the stationary phase used.
In HPLC: The Mobile Phase is a solvent. This solvent is pumped under high pressure through a column.
The Stationary Phase is a finely divided solid held inside the column.
What is HPLC anyway?High Performance Liquid Chromatography (HPLC) is a chemistry based tool for quantifying and analyzing mixtures of chemical compounds.
What is HPLC used for?It's used to find the amount of a chemical compound within a mixture of other chemicals. An example would be to find out how much caffeine there is in the cup of coffee (or tea, or cola).
What I must do to analyze the sample?Dissolve the sample in a solvent (like water or alcohol), thus the term LIQUID chromatography.
How do I measure the sample amount?A detector measures response changes between the solvent itself, and the solvent & sample when passing through it. The electrical response is digitized and sent to a data system.
Comparison of HPLC over Gas Chromatography Less volatile and larger samples can be used with HPLC. It was discovered that better separation of the components of the mixture occurs if the particles in the stationary phase are very small. However, it was also found that if very small particles were used in the column, then the liquid passed very slowly through the column. Therefore, a pump is used to force the liquid through the column. This is not necessary in GC but a shorter column can be used in HPLC because the separation is more efficient.
http://www.wesleylearning.ie/resources/science/chemistry/topics/instrumentation/hplc/principle.htm

Types
Types of HPLC
Normal phase chromatography
Normal phase HPLC (NP-HPLC) was the first kind of HPLC chemistry used, and separates analytes based on polarity. This method uses a polar stationary phase and a nonpolar mobile phase, and is used when the analyte of interest is fairly polar in nature. The polar analyte associates with and is retained by the polar stationary phase. Adsorption strengths increase with increase in analyte polarity, and the interaction between the polar analyte and the polar stationary phase (relative to the mobile phase) increases the elution time. The interaction strength not only depends on the functional groups in the analyte molecule, but also on steric factors and structural isomers are often resolved from one another. Use of more polar solvents in the mobile phase will decrease the retention time of the analytes while more hydrophobic solvents tend to increase retention times. Particularly polar solvents in a mixture tend to deactivate the column by occupying the stationary phase surface. This is somewhat particular to normal phase because it is most purely an adsorptive mechanism (the interactions are with a hard surface rather than a soft layer on a surface)..
NP-HPLC had fallen out of favor in the 1970's with the development of reversed-phase HPLC because of a lack of reproducibility of retention times as water or protic organic solvents changed the hydration state of the silica or alumina chromatographic media. Recently it has become useful again with the development of HILIC bonded phases which utilize a partition mechanism which provides reproducibility.

Reversed phase chromatography
Reversed phase HPLC (RP-HPLC) consists of a non-polar stationary phase and a moderately polar mobile phase. One common stationary phase is a silica which has been treated with RMe2SiCl, where R is a straight chain alkyl group such as C18H37 or C8H17. The retention time is therefore longer for molecules which are more non-polar in nature, allowing polar molecules to elute more readily. Retention time is increased by the addition of polar solvent to the mobile phase and decreased by the addition of more hydrophobic solvent. Reversed phase chromatography is so commonly used that it is not uncommon for it to be incorrectly referred to as "HPLC" without further specification.
RP-HPLC operates on the principle of hydrophobic interactions which result from repulsive forces between a relatively polar solvent, the relatively non-polar analyte, and the non-polar stationary phase. The driving force in the binding of the analyte to the stationary phase is the decrease in the area of the non-polar segment of the analyte molecule exposed to the solvent. This hydrophobic effect is dominated by the decrease in free energy from entropy associated with the minimization of the ordered molecule-polar solvent interface. The hydrophobic effect is decreased by adding more non-polar solvent into the mobile phase. This shifts the partition coefficient such that the analyte spends some portion of time moving down the column in the mobile phase, eventually eluting from the column.
The characteristics of the analyte molecule play an important role in its retention characteristics. In general, an analyte with a longer alkyl chain length results in a longer retention time because it increases the molecule's hydrophobicity. Very large molecules, however, can result in incomplete interaction between the large analyte surface and the alkyl chain. Retention time increases with hydrophobic surface area which is roughly inversely proportional to solute size. Branched chain compounds elute more rapidly than their corresponding isomers because the overall surface area is decreased.
Aside from mobile phase hydrophobicity, other mobile phase modifiers can affect analyte retention. For example, the addition of inorganic salts causes a linear increase in the surface tension of aqueous solutions, and because the entropy of the analyte-solvent interface is controlled by surface tension, the addition of salts tend to increase the retention time. Another important component is pH since this can change the hydrophobicity of the analyte. For this reason most methods use a buffering agent, such as sodium phosphate, to control the pH. An organic acid such as formic acid or most commonly trifluoroacetic acid is often added to the mobile phase. These serve multiple purposes: they control pH, neutralize the charge on any residual exposed silica on the stationary phase and act as ion pairing agents to neutralize charge on the analyte. The effect varies depending on use but generally improve the chromatography.
Reversed phase columns are quite difficult to damage compared with normal silica columns, however, many reverse phase columns consist of alkyl derivatized silica particles and should never be used with aqueous bases as these will destroy the underlying silica backbone. They can be used with aqueous acid but the column should not be exposed to the acid for too long, as it can corrode the metal parts of the HPLC equipment. The metal content of HPLC columns must be kept low if the best possible ability to separate substances is to be retained. A good test for the metal content of a column is to inject a sample which is a mixture of 2,2'- and 4,4'- bipyridine. Because the 2,2'-bipy can chelate the metal it is normal that when a metal ion is present on the surface of the silica the shape of the peak for the 2,2'-bipy will be distorted, tailing will be seen on this distorted peak.
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Size exclusion chromatography
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Size exclusion chromatography (SEC), also known as gel permeation chromatography or gel filtration chromatography, separates particles on the basis of size. It is generally a low resolution chromatography and thus it is often reserved for the final, "polishing" step of a purification. It is also useful for determining the tertiary structure and quaternary structure of purified proteins, and is the primary technique for determining the average molecular weight of natural and synthetic polymers.
Ion exchange chromatography
In Ion-exchange chromatography, retention is based on the attraction between solute ions and charged sites bound to the stationary phase. Ions of the same charge are excluded. Some types of Ion Exchangers include: (1) Polystyrene resins- allows cross linkage which increases the stability of the chain. Higher cross linkage reduces swerving, which increases the equilibration time and ultimately improves selectivity. (2) Cellulose and dextran ion exchangers (gels)-These possess larger pore sizes and low charge densities making them suitable for protein separation.(3)Controlled-pore glass or porous silica.
In general, ion exchangers favor the binding of ions of higher charge and smaller radius.
An increase in counter ion (with respect to the functional groups in resins) concentration reduces the retention time. An increase in pH reduces the retention time in cation exchange while a decrease in pH reduces the retention time in anion exchange.
This form of chromatography is widely used in the following applications: In purifying water, preconcentration of trace components, Ligand-exchange chromatography, Ion-exchange chromatography of proteins, High-pH anion-exchange chromatography of carbohydrates and oligosaccharides, etc.
Bioaffinity chromatography
This chromatographic process relies on the property of biologically active substances to form stable, specific, and reversible complexes. The formation of these complexes involves the participation of common molecular forces such as the Van der Waal's interaction, electrostatic interaction, dipole-dipole interaction, hydrophobic interaction, and the hydrogen bond. An efficient, biospecific bond is formed by a simultaneous and concerted action of several of these forces in the complementary binding sites.
Isocratic flow and gradient elution
With regard to the mobile phase, a composition that remains constant throughout the procedure is termed isocratic.
In contrast to this is the so called "gradient elution", which is a separation where the mobile phase changes its composition during a separation process. One example is a gradient in 20 min starting from 10% Methanol and ending up with 30% Methanol. Such a gradient can be increasing or decreasing. The benefit of gradient elution is that it helps speed up elution by allowing components that elute more quickly to come off the column under different conditions than components which are more readily retained by the column. By changing the composition of the solvent, components that are to be resolved can be selectively more or less associated with the mobile phase as a result at equilibrium they spend more time in the solvent and less in the stationary phase therefore they elute faster.
Gas-liquid chromatography

(GLC), or simply gas chromatography (GC), is a type of chromatography in which the mobile phase is a carrier gas, usually an inert gas such as helium or an unreactive gas such as nitrogen, and the stationary phase is a microscopic layer of liquid or polymer on an inert solid support, inside glass or metal tubing, called a column. The instrument used to perform gas chromatographic separations is called a gas chromatograph (also: aerograph, gas separator).
A gas chromatograph is a chemical analysis instrument for separating chemicals in a complex sample. A gas chromatograph uses a flow-through narrow tube known as the column, through which different chemical constituents of a sample pass in a gas stream (carrier gas, mobile phase) at different rates depending on their various chemical and physical properties and their interaction with a specific column filling, called the stationary phase. As the chemicals exit the end of the column, they are detected and identified electronically. The function of the stationary phase in the column is to separate different components, causing each one to exit the column at a different time (retention time). Other parameters that can be used to alter the order or time of retention are the carrier gas flow rate, and the temperature.
In a GC analysis, a known volume of gaseous or liquid analyte is injected into the "entrance" (head) of the column, usually using a microsyringe (or, solid phase microextraction fibers, or a gas source switching system). As the carrier gas sweeps the analyte molecules through the column, this motion is inhibited by the adsorption of the analyte molecules either onto the column walls or onto packing materials in the column. The rate at which the molecules progress along the column depends on the strength of adsorption, which in turn depends on the type of molecule and on the stationary phase materials. Since each type of molecule has a different rate of progression, the various components of the analyte mixture are separated as they progress along the column and reach the end of the column at different times (retention time). A detector is used to monitor the outlet stream from the column; thus, the time at which each component reaches the outlet and the amount of that component can be determined. Generally, substances are identified (qualitatively) by the order in which they emerge (elute) from the column and by the retention time of the analyte in the column.

Thin Layer Chromatography (TLC) is a widely-used chromatography technique used to separate chemical compounds [1]. It involves a stationary phase consisting of a thin layer of adsorbent material, usually silica gel, aluminium oxide, or cellulose immobilised onto a flat, inert carrier sheet. A liquid phase consisting of the solution to be separated dissolved in an appropriate solvent is drawn through the plate via capillary action, separating the experimental solution. It can be used to determine the pigments a plant contains, to detect pesticides or insecticides in food, in forensics to analyze the dye composition of fibers, or to identify compounds present in a given substance, among other uses. It is a quick, generic method for organic reaction monitoring.
TLC plates are made by mixing the adsorbent, such as silica gel, with a small amount of inert binder like calcium sulfate (gypsum) and water. This mixture is spread as a thick slurry on an unreactive carrier sheet, usually glass, thick aluminum foil, or plastic, and the resultant plate is dried and activated by heating in an oven for thirty minutes at 110 °C. The thickness of the adsorbent layer is typically around 0.1–0.25 mm for analytical purposes and around 1–2 mm for preparative TLC. Every type of chromatography contains a mobile phase and a stationary phase
The process is similar to paper chromatography with the advantage of faster runs, better separations, and the choice between different stationary phases. Because of its simplicity and speed TLC is often used for monitoring chemical reactions and for the qualitative analysis of reaction products.
A small spot of solution containing the sample is applied to a plate, about one centimeter from the base. The plate is then dipped in to a suitable solvent, such as ethanol or water, and placed in a sealed container. The solvent moves up the plate by capillary action and meets the sample mixture, which is dissolved and is carried up the plate by the solvent. Different compounds in the sample mixture travel at different rates due to differences in solubility in the solvent, and due to differences in their attraction to the stationary phase. Results also vary depending on the solvent used. For example, if the solvent were a 90:10 mixture of hexane to ethyl acetate, then the solvent would be mostly nonpolar. This means that when analyzing the TLC, the nonpolar parts will have moved further up the plate. The polar compounds, in contrast, will not have moved as much. The reverse is true when using a solvent that is more polar than non-polar (10:90 hexane to ethyl acetate). With these solvents, the polar compounds will move higher up the plate, while the non-polar compounds will not move as much.
The appropriate solvent in context of Thin layer chromatography will be one which differs from the stationary phase material in polarity. If polar solvent is used to dissolve the sample and spot is applied over polar stationary phase TLC, the sample spot will grow radially due to capillary action, which is not advisable as one spot may mix with the other. Hence, to restrict the radial growth of sample-spot, the solvent used for dissolving samples in order to apply them on plates should be as non-polar or semi-polar as possible when the stationary phase is polar, and vice-versa.

Chromatogram of 10 essential oils coloured with vanillin reagent.
As the chemicals being separated may be colorless, several methods exist to visualize the spots:
Often a small amount of a fluorescent compound, usually Manganese-activated Zinc Silicate, is added to the adsorbent that allows the visualization of spots under a blacklight(UV254). The adsorbent layer will thus fluoresce light green by itself, but spots of analyte quench this fluorescence.
Iodine vapors are a general unspecific color reagent
Specific color reagents exist into which the TLC plate is dipped or which are sprayed onto the plate
Once visible, the Rf value of each spot can be determined by dividing the distance traveled by the product by the total distance traveled by the solvent (the solvent front). These values depend on the solvent used, and the type of TLC plate, and are not physical constants.
http://en.wikipedia.org/wiki/Thin_layer_chromatography

Atomic absorption spectroscopy
(often called AA) - This method commonly uses a pre-burner nebulizer (or nebulizing chamber) to create a sample mist and a slot-shaped burner which gives a longer pathlength flame. The temperature of the flame is low enough that the flame itself does not excite sample atoms from their ground state. The nebulizer and flame are used to desolvate and atomize the sample, but the excitation of the analyte atoms is done by the use of lamps shining through the flame at various wavelengths for each type of analyte. In AA, the amount of light absorbed after going through the flame determines the amount of analyte in the sample. A graphite furnace for heating the sample to desolvate and atomize is commonly used for greater sensitivity. The graphite furnace method can also analyze some solid or slurry samples. Because of its good sensitivity and selectivity, it is still a commonly used method of analysis for certain trace elements in aqueous (and other liquid) samples.
Atomic absorption spectroscopy (AAS) determines the presence of metals in liquid samples. Metals include Fe, Cu, Al, Pb, Ca, Zn, Cd and many more. It also measures the concentrations of metals in the samples. Typical concentrations range in the low mg/L range.
In their elemental form, metals will absorb ultraviolet light when they are excited by heat. Each metal has a characteristic wavelength that will be absorbed. The AAS instrument looks for a particular metal by focusing a beam of uv light at a specific wavelength through a flame and into a detector. The sample of interest is aspirated into the flame. If that metal is present in the sample, it will absorb some of the light, thus reducing its intensity. The instrument measures the change in intensity. A computer data system converts the change in intensity into an absorbance.
As concentration goes up, absorbance goes up. The researcher can construct a calibration curve by running standards of various concentrations on the AAS and observing the absorbances. In this lab, the computer data system will draw the curve for you! Then samples can be tested and measured against this curve.
http://www.gmu.edu/departments/SRIF/tutorial/aas/aas.htm

Protein electrophoresis

Definition
Electrophoresis is a technique used to separate different elements (fractions) of a blood sample into individual components. Serum protein electrophoresis (SPEP) is a screening test that measures the major blood proteins by separating them into five distinct fractions: albumin, alpha1, alpha2, beta, and gamma proteins. Protein electrophoresis can also be performed on urine.
Purpose
Protein electrophoresis is used to evaluate, diagnose, and monitor a variety of diseases and conditions. It can be used for these purposes because the levels of different blood proteins rise or fall in response to such disorders as cancer, intestinal or kidney protein-wasting syndromes, disorders of the immune system, liver dysfunction, impaired nutrition, and chronic fluid-retaining conditions.
Precautions
Certain other diagnostic tests or prescription medications can affect the results of SPEP tests. The administration of a contrast dye used in some other tests may falsely elevate protein levels. Drugs that can alter results include aspirin, bicarbonates, chlorpromazine (Thorazine), corticosteroids, isoniazid (INH), and neomycin (Mycifradin).
Description
Proteins are major components of muscle, enzymes, hormones, hemoglobin, and other body tissues. Proteins are composed of elements that can be separated from one another by several different techniques: chemical methods, ultracentrifuge, or electrophoresis. There are two major types of electrophoresis: protein electrophoresis and immunoelectrophoresis. Immunoelectrophoresis is used to assess the blood levels of specific types of proteins called immunoglobulins. An immunoelectrophoresis test is usually ordered if a SPEP test has a "spike," or rise, at the immunoglobulin level. Protein electrophoresis is used to determine the total amount of protein in the blood, and to establish the levels of other types of proteins called albumin, alpha1 globulin, alpha2 globulin, and beta-globulin
Electrophoretic measurement of proteins
All proteins have an electrical charge. The SPEP test is designed to make use of this characteristic. There is some difference in method, but basically the sample is placed in or on a special medium (e.g., a gel), and an electric current is applied to the gel. The protein particles move through the gel according to the strength of their electrical charges, forming bands or zones. An instrument called a densitometer measures these bands, which can be identified and associated with specific diseases. For example, a decrease in albumin with a rise in the alpha2 globulin usually indicates an acute reaction of the type that occurs in infections, burns, stress, or heart attack. On the other hand, a slight decrease in albumin, with a slight increase in gammaglobulin, and a normal alpha2 globulin is more indicative of a chronic inflammatory condition, as might be seen in cirrhosis of the liver.
Protein electrophoresis is performed on urine samples to classify kidney disorders that cause protein loss. Here also certain band patterns are specific for disease. For example, the identification of a specific protein called the Bence Jones protein (by performing the Bence Jones protein test) during the procedure suggests multiple myeloma.
http://www.healthatoz.com/healthatoz/Atoz/common/standard/transform.jsp?requestURI=/healthatoz/Atoz/ency/protein_electrophoresis.jsp

DNA electrophoresis is an analytical technique used to separate DNA fragments by size. An electric field forces the fragments to migrate through a gel. DNA molecules normally migrate from negative to positive potential due to the net negative charge of the phosphate backbone of the DNA chain. At the scale of the length of DNA molecules, the gel looks much like a random, intricate network. Longer molecules migrate more slowly because they are more easily 'trapped' in the network.
After the separation is completed, the fractions of DNA fragments of different length are often visualized using a fluorescent dye specific for DNA, such as ethidium bromide. The gel shows bands corresponding to different DNA molecules populations with different molecular weight. Fragment size is usually reported in "nucleotides", "base pairs" or "kb" (for 1000's of base pairs) depending upon whether single- or double-stranded DNA has been separated. Fragment size determination is typically done by comparison to commercially available DNA ladders containing linear DNA fragments of known length.
The types of gel most commonly used for DNA electrophoresis are agarose (for relatively long DNA molecules) and polyacrylamide (for high resolution of short DNA molecules, for example in DNA sequencing). Gels have conventionally been run in a "slab" format such as that shown in the figure, but capillary electrophoresis has become important for applications such as high-throughput DNA sequencing. Electrophoresis techniques used in the assessment of DNA damage include alkaline gel electrophoresis and pulsed field gel electrophoresis. The measurement and analysis are mostly done with a specialized gel analysis software. Capillary electrophoresis results are typically displayed in a trace view called an electropherogram.

The DNA strand is cut into smaller fragments using DNA endonuclease, then samples of the DNA solution (DNA sample and buffer) is placed in the wells of the gel, and allowed to run for some time (the less the voltage of the electophoresis, te longer time for the DNA sample to run through the gel, and this results in a more accurate separation). method for DNA electrophoresis
http://en.wikipedia.org/wiki/DNA_electrophoresis

2007-07-24T04:34:00.000-07:00

Detection of aflatoxins

Cultural methods for detection of aflatoxins:

Aflatoxins present important food safely problems in both developed and developing countries. Contamination is monitored in developed countries using enzyme-linked immunusorbent assay (ELISA)- and high-performance liquid chromatography (HPLC)-based assays, both of which may be too expensive for routine use in many developing countries. There is a need for inexpensive alternative approaches to detect aflatoxins in lots of foods and feeds. Reviewed here are culture-based methods that determine if a sample is contaminated with aflatoxigenic fungi. These approaches include (1) blue fluorescence of aflatoxin B1, particularly when enhanced by including ß-cyclodextrin in the culture medium, (2) yellow pigment production, and (3) colour change on exposure to ammonium hydroxide vapour. The presence of aflatoxin B1 can be detected by its blue fluorescence, which is enhanced when the toxin complexes with the hydrophobic pocket of ß-cyclodextrin. The yellow pigment and ammonium hydroxide vapour tests are based on the production of yellow anthraquinone biosynthetic intermediates in the aflatoxin pathway. These compounds act as pH indicator dyes, which are more visible when they have turned red at alkaline pH. Because these tests are based on two different mechanisms, it has been possible to combine them into a single test. In a study of 517 A. flavus isolates from the Mississippi Delta, the combined assay reduced false positives for aflatoxigenicity to 0%, and false negatives to 7%. The increased predictive power of the combined cultural assay may enable its use for inexpensively identifying
potential aflatoxin contamination in feeds and foods

http://www.cababstractsplus.org/google/abstract.asp?AcNo=20043182722

HOW CAN IT BE DETECTED?

Since most samples do not contain a detectable amount of aflatoxin, there is a need for a method which correctly identifies the many negative samples with minimum expenditure of time and money. Such a method is known as the BLACK LIGHT TEST and UVP BLAK-RAY® lamps are recommended for this application. Refer to UVP Brochure 818.
The aflatoxins all have absorption maxima around 360nm with a molar absorptivity of about 20,000: the B toxins are named for their blue fluorescence (425nm) and the G toxins for their green-blue fluorescence (450nm). The B1 toxin is the most common, flowed by B2 toxin, while the G toxins are fairly rare. The fluorescence sensitivity of the G toxins is more than 10 times greater than that for the B toxins. The minimum detectable level is about 100 pgrams for the G toxins and 1 ngram for the B toxins.
Corn is inspected under the BLAK-RAY lamp for a characteristic bright greenish-yellow (BGY) fluorescence in broken and damaged kernels. The test takes 5 minutes or less. If the fluorescence is observed, aflatoxin may be present but not necessarily in appreciable or detectable levels. There are substances in corn and other food that fluoresce under long wave ultraviolet irradiation, but are not associated with aflatoxin. Many other fungi such as Aspergillus niger, various Penicillium species, Aspergillus repens and other species which do not produce aflatoxin may produce fluorescent harmless metabolites so that the fluorescence is not a specific indication of the presence of toxicogenic molds, although it may indicate that conditions have been favorable for growth of the toxicogenic molds.
Additionally, A. flavus, isolated from corn, has displayed a broad spectrum of aflatoxin production, ranging from no detectable yields to high levels (>100 ppm). A probable contributory factor to this is that the fluorescence in naturally contaminated corn is not stable and disappears in 4 to 6 weeks on continuous exposure to visible or ultraviolet radiation although the toxin does not disappear. Fresh samples mush therefore be taken.
The reliability of the method depends on the size of the sample taken for analysis and how it is taken. A sample mush be large enough to be representative of the entire lot of corn and must be taken from all parts of the lot–whether bin, truck or railroad car. One highly contaminated corn kernel may account for objectionable levels of aflatoxin in a 3000-kernel (2 lb.) sample. If only a 1 to 2 lb. sample is collected, the one highly contaminated kernel could be missed. Usually from 5 to 10 lb. samples are collected, but even larger ones would be better. If the sampling is not performed properly, the results obtained by this screening method could be of little value.
The black light test is an excellent screening test for possible presence of aflatoxin, but it does not give quantitative indication. Even with good technique, brightly fluorescing samples may contain less aflatoxin than weakly fluorescing samples. Because of this, additional confirmatory and quantitative measurements are needed to be applied to those samples that reacted positively to the black light test. Non-fluorescing samples need not be subjected to this.

FURTHER SCREENING
Since the black light test is only a preliminary confirmatory test, another screening test is used in feed mills immediately following the black light test. This test involves the use of a small chromatographic column (mini-column) in the final separation and detection step of the method.
If the black light test gives a positive answer, the 10 lb. sample of cracked corn is ground to pass a twenty-mesh screen and the mixed thoroughly. A 50 g representative subsample of the 10 lb. of finely ground corn is used for the mini-column test. The final separation step of the mini-column method involves transferring 3 ml of chloroform extract to the top of a mini-column. After the chloroform drains into the column, 3 ml of an elution solvent are passed through the mini-column.
The mini-column is then inspected in the dark by shining a long wave black light on it. This, again, should be one of the BLAK-RAY lamps. If a bluish-green fluorescent band is detected at the proper height in the mini-column, the sample is judged to be positive to aflatoxin. In this instance, the property detected by the test is the bluish-green fluorescence.
This test, like the black light test, is a good screening test because it gives few false negative answers. However, this test also has the characteristic of giving only a few false positive answers. This makes it a better screening test, from a scientific viewpoint, than the black light test; however, it is better cost wise to run the two tests one after the other.
After the mini-column test is completed, a judgment can be made as to whether or not a shipment of corn will be accepted by a feed mill. The changes of accepting a truckload of corn that contains more than the 20 ppb aflatoxin is slight, as is the chance of rejected a truckload of corn that does not contain detectable aflatoxin.
If further confirmation is required, a subsample of the ground sample of corn can be sent to a chemical laboratory, or the extract remaining from the mini-column test can be used for a simple confirmatory test.
In this test, a portion of the chloroform extract not used for the mini-column test is evaporated to a small volume and some of this concentrated extract is spotted on a thin layer plate. A small amount of trifluoroacetic acid (TFA) is placed on top of the spot where the sample extract was placed. If aflatoxin is present in the sample spot on the thin layer plate, it will be derivatized to a water adduct of the parent aflatoxin compound. After thin layer chromatography is performed, this plate is inspected in the dark under a long wave black light. If a bluish-green fluorescent spot is detected on the thin layer plate at the same height as a reference spot known to be the derivative of aflatoxin formed by the TFA reaction, this confirmatory test (the TFA test) is positive and the concentration probably greater than 5 to 10 ppb.

QUALITATIVE TESTS
Although the TFA test is a confirmatory test, it is not essentially different from the mini-column test. Both are qualitative tests, that is, both test for qualities or properties of aflatoxin. The final property of aflatoxin involved in the mini-column test is the property fluorescing bluish-green under a long wave black light.
The TFA test involves three additional properties of aflatoxin. One of the properties involved is that aflatoxin will form a derivative in the presence of trifluoroacetic acid while on a thin layer plate at room temperature. Another property is that this derivative will move to a certain height on the thin layer plate using a certain developing solvent. A third property is that this derivative will fluoresce bluish-green under a long wave black light.
However, even if this test also is positive, we are still not 100% certain that aflatoxin has been detected. At this point, the degree of certainty is probably over 99%.
If we desire a further confirmation that aflatoxin is in the sample, a small amount of the underivatized compound can be isolated on a thin layer plate and extracted. This small amount of sample can then be inserted into the entrance of a mass spectrometer. The mass spectrometer is an instrument, which will break the aflatoxin into many fragments. The original mass of the aflatoxin molecule, plus that of each of the fragments produced, will be indicated by the output of the instrument.
The pattern of the various masses is characteristic of the particular aflatoxin involved. If the pattern of the chemical suspected to be aflatoxin is identical with the pattern given by a know aflatoxin, we are about 99.99% certain that the suspect chemical is aflatoxin

http://www.coleparmer.com/techinfo/techinfo.asp?htmlfile=aflotoxin.htm&ID=6

2007-07-24T04:30:00.000-07:00

What is toxins?

Toxin 1. any of various poisons produced by microorganisms and causing certain diseases 2. any poison secreted by plants or animals (Agnes 1996).
Toxins-Poisons (usually proteins) produced by living organisms, especially those capable of stimulating the production of antibodies (Art 1993).

http://www.bio.davidson.edu/courses/anphys/2000/Todd/toxin.htm

Types of toxins:

Alflatoxins

General Facts About Aflatoxins
Aflatoxins are naturally occurring toxins that are metabolic byproducts of fungi, Aspergillus flavus, and Aspergillus parasiticus, which grow on many food crops under favorable conditions.
Aflatoxin is an mycotoxin literally means poison from a fungi and are named on the basis of the fungus that produces them, thus “Aflatoxin” uses the “A” for Aspergillus and “fla” for the species “flavus” along with the word toxin.
Adverse impact on animal and human health with acute toxicological effects such as liver damage and cancer can occur.
The major types of aflatoxins are B1, B2, G1, G2, and M1, with aflatoxin B1 being the most toxic, and usually predominant. Aflatoxin B1 is a very potent carcinogen to humans and animals.
Aflatoxins can invade the food supply at anytime during production, processing, transport or storage.
Conditions that contribute to fungal growth and the production of aflatoxins are: a hot and humid climate, kernel moisture, favorable substrate characteristics, and factors that decrease the host plant’s immunity (insect damage, poor fertilization, and drought).
Food and food crops most prone to contamination are corn and corn products, cottonseed, peanuts and peanut products, tree nuts (pistachio nuts, pecans, walnuts, Brazil nuts) and milk.

FDA Action Levels for Aflatoxins

Food and Drug Administration (FDA) has established action levels for aflatoxin present in food or feed to protect human and animal health.*
Levels must not exceed:

20 ppb - For corn and other grains intended for immature animals (including immature poultry) and for dairy animals, or when its destination is not known;
20 ppb - For animal feeds, other than corn or cottonseed meal;
100 ppb - For corn and other grains intended for breeding beef cattle, breeding swine, or mature poultry;
200 ppb - For corn and other grains intended for finishing swine of 100 pounds or greater;
300 ppb - For corn and other grains intended for finishing (i.e., feedlot) beef cattle and for cottonseed meal intended for beef cattle, swine or poultry.

Taken from: http://fsrio.nal.usda.gov/research_topics_index.php?topic=nat_toxins

2007-07-24T04:23:00.000-07:00

Toxins research

What are the toxins?

Toxins can be classify into natural toxins already presence in foods itself
Toxins that are produced after genetically modifying them.

Toxins Detection methods:

The array biosensor is capable of detecting multiple targets rapidly and simultaneously on the surface of a single waveguide. Sandwich and competitive fluoroimmunoassays have been developed to detect high and low molecular weight toxins, respectively, in complex samples. Recognition molecules (usually antibodies) were first immobilized in specific locations on the waveguide and the resultant patterned array was used to interrogate up to 12 different samples for the presence of multiple different analytes. Upon binding of a fluorescent analyte or fluorescent immunocomplex, the pattern of fluorescent spots was detected using a CCD camera. Automated image analysis was used to determine a mean fluorescence value for each assay spot and to subtract the local background signal. The location of the spot and its mean fluorescence value were used to determine the toxin identity and concentration. Toxins were measured in clinical fluids, environmental samples and foods, with minimal sample preparation. Results are shown for rapid analyses of staphylococcal enterotoxin B, ricin, cholera toxin, botulinum toxoids, trinitrotoluene, and the mycotoxin fumonisin. Toxins were detected at levels as low as 0.5 ng mL–1.
Keywords Biosensor - Immunosensor - Array - Multi-analyte - Toxin - Detection
http://www.springerlink.com/content/7epu6q4rqtnmv98h/

About Bt toxins:

Bacillus thuringiensis produces crystal toxins and cytolytic toxins, the cytolytic toxins compliment the crystals and improve the bacterium’s ability to control insects. Bacillus thuringiensis is classified as a bacterium that produces delta-endotoxins, consisting of three domains. The structures of the three Domains are all significant in the bacterium’s lethality to insects; Domain 1 is composed of 7 alpha-helices, which can bore holes in the insect’s gut. Domain 2 has three antiparallel beta-pleated sheets, which help the antigens bind to the gut, and Domain 3 is tightly packed, which prevents binding of the gut protease (The Microbial World 2001). Because the bacterium is composed of several crystal proteins, the toxins produced have a unique “targeting affect.” Due to the fact that currently, only one of the crystal protein toxins can be affectively isolated from the bacterium at once, the natural insecticide is lethal to only a few species, depending on which protein is isolated (Tabashnik, 2002). The three types of proteins produced by the Bacillus thuringiensis bacterium are the Cry1Ab, the Cry1Ac, and the Cry3A protein. These crystal endotoxins are found in the N-terminal section of the protein. The Cry1Ab protein is lethal against the European corn borer worm and is the protein used when dealing with Bt corn plants. In Bt cotton, the Cry1Ac protein is affective against the Tobacco budworm and the Cotton bollworm. Lastly, the Cry3A protein targets the Colorado potato beetle and is used when protecting potato plants (Peferoen, 1997). Due to the fact that Bacillus thuringiensis is only lethal to a small variety of insect species, many non-threatening or beneficial insects survive. However, there much research is being conducted on incorporating all three Cry proteins into a plant’s genome. With all three proteins augmenting each other, the result is a crop that is resistant to all types of Lepidopteron and a few species of the Coleopteran family. This new Bt plant, or “Bt2”, solves a common problem that cotton farmers struggle with each growing season. Since Bt1 only isolates the Cry1Ac protein and is lethal solely against Tobacco budworms and Cotton bollworms, the Fall and Beet Armyworms, which are major destructive species, are not affected. Therefore, Bt2 virtually eliminates all of the major Lepidopteron pests that hinder high cotton yields.

http://teach.valdosta.edu/rgoddard/PlPhys/Chris/Btcrops.htm

2007-07-24T04:22:00.000-07:00

ADI levels for fumonosins

I could not search for the ADI but I search a lot of the TDI

Tolerable Daily Intake of 2 g/kg body weight/day set by the Joint FAO/WHO

http://www.mrc.ac.za/promec/annual.htm

Principles of ELISA

2007-07-24T04:17:00.000-07:00

Principles Of ELISA

1. Begins with an antibody bound to a polystyrene well.

2. Plus a test sample containing an antigen mixture to which an antigen-enzyme conjugate is added.

3. At this point, competitive inhibition occurs between the antigen-enzyme conjugate and an unlabeled antigen, depending on which antigen type is in excess, two different outcomes can follow when binding to a specific antibody occurs. After the formation of an immune complex from an antigen-antibody binding.

4. The reagents are separated by washing. Next a substrate is added to the immune complex

5. If the antigen-enzyme conjugate is the antigen in excess a color change will occur indicating that the substrate was chemically changed as a result of the enzyme conjugate being bound to the immune complex

6. If it is the unlabeled antigen that is in excess there will be little to no change in color because the test sample contains antibody-type-specific antigen

http://analytical.chem.wisc.edu/524class/Folders/Chow/ELISAb.html

Principle for Indirect Competitive Antibody Capture ELISAs

1. Immobilization reactionA standard analyte (antigen) is immobilized on a solid phase (microtiter plate well).

2. Competition reactionThe sample is added together with a primary antibody specific for the analyte. The analyte in the sample competes with the standard analyte on the solid phase for binding to the antibody. Unbound components are washed away.

3. Binding of enzyme-labelled antibodyAn enzyme-labelled antibody binding to the primary antibody is added. Unbound antibody is washed away.

4. Chromogenic reactionA non-coloured substrate is added, and the substrate is converted to a coloured product by the enzyme bound to the antigen-antibody complex.

5. Quantitative analysisThe colour intensity is measured with a microplate reader and is inversely proportional to the concentration of analyte in the sample. The relationship between absorbance and analyte concentration is obtained from a standard curve created from a reference material.

Prinicples of elisa

2007-07-24T04:13:00.000-07:00

The Myco4test kit for fumonisin is a 10 minute (two 5 minute incubations) competitive enzyme-linked immunosorbent assay. The microtiter strip well test will detect the quantitative presence of fumonisin in corn and corn products (excluding corn gluten meal and corn gluten feed) in a range of 0 to 6.0 ppm. The principles of the test are based on the ability of free toxin, extracted from the sample, to compete with the enzyme-toxin conjugate (enzyme-labeled toxin supplied in the test kit) for antibody binding sites on the test wells. After a brief washing step, substrate is added to the wells which reacts with the bound enzyme conjugate to develop a blue color. The darker the blue color the lower the levels of toxin. The lighter the blue color the higher the levels of toxin. The test results may be read qualitatively visually or read in a microwell reader at 650 nm to provide quantitative results. The concentration of the toxin is determined by comparison to a standard curve. Up to 38 samples may be run using the 48 well test kit. Due to the speed of the test the maximum amount of wells run at one given time is 24 or two strips of 12. Running the test this way will provide a maximum amount of 19 sample wells. The test kit has been calibrated to a mixture of fumonisin B1, B2 and B3 at 5:2:1 ratios against the kit standard. The test kit and is cross-reactive to fumonisin B1 (97%), B2 (128%) and B3 (83%).

http://www.sdix.com/PDF/Products/User%20Guide%20Myco%20Fumonisin%201.5.doc

DNA sensor for detection of fumonisins

2007-07-24T04:11:00.000-07:00

Detection of Fusarium culmorum in wheat by a surface plasmon resonance-based DNA sensor
A surface plasmon resonance (SPR) sensor based on DNA hybridization has been developed for the detection of Fusarium culmorum, a fungal pathogen of cereals. A 0.57 kbp DNA fragment of F. culmorum was amplified by specific primers and a 25-mer oligonucleotide probe was selected within the sequence of the PCR amplicon. After biotinilation, the probe was immobilized on a streptavidin sensor chip and tested for biospecific interaction with PCR products of F. culmorum. The effect of denaturating agents (formamide and urea) and ionic strength (NaCl) on hybridization efficiency of double-stranded PCR products with the immobilized probe and the specificity of the probe were investigated. The SPR biosensor was successfully used for the detection of F. culmorum in culture material of different strains and in naturally infected wheat samples. Tested on fungal cultures, it showed a good selectivity for F. culmorum against other species of either Fusarium or other fungal genera. A background signal was observed in wheat samples strictly depending on the DNA amount of the testing matrix. Testing 30 ng of durum wheat DNA the detection limit was 0.06 pg of F. culmorum DNA. The developed PCR-SPR assay allowed to detect F. culmorum with sensitivity and specificity higher than gel-electrophoresis analysis.

http://www.sciencedirect.com/science?_

PCR detection of fumonosins

2007-07-24T04:09:00.000-07:00

PCR-ELISA for the detection of potential fumonisin producing Fusarium species has been developed, using the ribosomal ITS1 sequence as target. For this purpose, the sequences of the ITS1 regions of different fumonisin producing Fusarium species have been determined and compared to the sequences of fumonisin non-producing species. In general, the ITS1 sequences were highly homologous. However, some minor sequence polymorphisms were detected, which differentiates potential fumonisin producing Fusarium species from non-producing species. By using these sequence differences, a PCR-ELISA for potential fumonisin producing Fusarium species was developed. All other ubiquitously occurring food-borne fungi tested showed negative results with this test.

http://www.medscape.com/medline/abstract/9717319

Immunosassay for fumonisins

2007-07-24T04:07:00.000-07:00

An indirect enzyme-linked immunosorbent assay (ELISA) was developed to detect Fusarium species in foods. Antibodies to proteins extracted from the mycelia of Fusarium graminearum and Fusarium moniliforme (verticillioides) were produced in New Zealand white rabbits. These antibodies detected 13 Fusarium species in addition to the producer strains.

http://www.ingentaconnect.com/content/iafp/jfp/2003/00000066/00000003/art00016

Detection for fumonisins

2007-07-24T04:04:00.000-07:00

Screening tests for fumonisins are based either on thin-layer chromatography (TLC) separation after appropriate clean-up of maize extracts or on commercially available enzyme-linked immunosorbent assays (ELISAs). Other immunologically based methods, such as dipstick (Schneider et al., 1995) and biosensor methods (Thompson & Maragos, 1996; Maragos, 1997; Mullett et al., 1998), have been described but have not found general use. Immunoaffinity columns have been designed to purify extracts before high-performance liquid chromatography (HPLC) separation and quantification of fumonisins B1, B2, and B3 analogues, and have also been used in a direct fluorimetric method for rapid determination of ‘total fumonisin’ (Duncan et al., 1998).
The TLC and other chromatographic methods for fumonisins have been reviewed (Shephard, 1998). The reversed-phase technique developed by Rottinghaus et al. (1992) has been used in surveys of contamination of maize with fumonisins (Shelby et al., 1994a). When combined with an efficient extract clean-up procedure based on use of immunoaffinity columns and detection by densitometry, TLC can be considered quantitative (Preis & Vargas, 2000).
The performance characteristics of screening tests for fumonisins in maize, based on interlaboratory collaborative studies, have not been reported in the literature. However, in-house comparisons between HPLC methods and the various screening tests have been described. The TLC method of Rottinghaus et al. (1992) has been compared with HPLC over a contamination range of fumonisin B1 of 1–250 mg/kg (correlation coefficient, r = 0.953; p < 0.0005; Schaafsma et al., 1998). The results obtained with a fibre-optic immunosensor in a direct competitive monoclonal antibody format with a fumonisin B1–fluorescein isothiocyanate conjugate compare favourably with those obtained with HPLC (Maragos, 1997).
The commercial availability of ELISA methods has made them popular for screening for fumonisin contamination. Although the antibodies used in ELISAs are raised against fumonisin B1, they generally have significant (but lower) cross-reactivity with fumonisins B2 and B3. The performance of ELISAs is generally assessed by comparison with HPLC determination of fumonisins and has been found to depend on the antibody used (Pestka et al., 1994; Usleber et al., 1994; Sydenham et al., 1996a,b; Kulisek & Hazebroek, 2000). The correlation between the results of HPLC and ELISA for naturally contaminated samples has been reported to vary from 0.51 (p < 0.05; Pestka et al., 1994) to 0.97 (p < 0.001; Sydenham et al., 1996a). However, such comparisons have generally shown an overall trend for the concentrations of ‘total fumonisins’ with ELISA to be greater than those determined in the same samples by HPLC

http://www.inchem.org/documents/jecfa/jecmono/v47je03.htm#3.0

Pests develop resistance to single-gene GM crops: study

2007-07-19T15:27:00.000-07:00

Insects may rapidly develop resistance to killing toxins produced by genetically modified (GM) crops that are inserted with only one insecticidal gene, US researchers reported on Friday.
Genes of a soil bacterium called Bacillus thuringiensis (Bt) are inserted into crop plants such as maize and cotton, creating toxins deadly to insects but harmless to humans. Bt crops have been commercialized since 1996, but some scientists are concerned that use of Bt crops would create conditions for insects to evolve and develop resistance to the toxins.
Until now, it has not been shown if neighboring plants producing a single Bt toxic protein might play a role in insect resistance to transgenic crops expressing two insecticidal proteins. But a research group from Cornell University found when crops engineered with just one of those toxins grow nearby, insects may more rapidly develop resistance to all the insect- killing plants.
"Our findings suggest that concurrent use of single- and dual- gene Bt plants can put the dual-gene plants at risk if single-gene plants are deployed in the same area simultaneously," said Anthony Shelton, professor at Cornell University who led the study. Their paper was published in the latest issue of the Proceedings of the National Academy of Sciences (PNAS).
"Single-gene plants really function as a steppingstone in resistance of two-gene plants if the single gene plants contain one of the same Bt proteins as in the two-gene plant," Shelton said.
Cotton and maize are the only commercial crops engineered with Bt genes. In 2004 these crops were grown on 22.4 million hectares worldwide. After eight years of extensive use, there have been no reports of crop failure or insect resistance in the field to genetically modified Bt crops, Shelton said.
Still, several insects have developed resistance to Bt toxins in the lab, and recently, cabbage loopers, a moth whose larvae feed on plants in the cabbage family, have shown resistance to Bt sprays in commercial greenhouses.
Diamondback moths used in this study have also developed resistance to Bt toxins in the field. In greenhouse studies, the researchers used three types of GM broccoli plants: two types of plants each expressed a different Bt toxin, and a third, known as a pyramided plant, expressed both toxins.
First, the researchers bred moth populations in which a low percent of the moths were resistant to a single Bt toxin. The insects were then released into caged growing areas with either single-gene plants, dual-gene plants or mixed populations and allowed to reproduce for two yea
They found that the insects living in the greenhouse with single-gene and dual-gene plants housed together damaged all the plants after 26 generations, because more insects developed resistance to the plants' toxins overtime. However, in the same two-year time frame, all or almost all of the insects died when exposed to pyramided plants alone.
"It's easier for an insect to develop resistance to a single toxin," said Shelton. "If an insect gets a jump on one toxin, then it becomes more rapidly resistant to that same toxin in a dual- gene plant."
While single-gene Bt plants are most prevalent, industry trends suggest that pyramided plants may be favored in the future. In the United States, companies introduced dual-gene cotton in 2003, but single-gene varieties remain on the market.
"Single-gene Bt plants have provided good economic and environmental benefits, but from a resistance management standpoint they are inferior to dual-gene plants. US regulatory agencies should consider discontinuing the use of those single- gene plants as soon as dual-gene plants become available," Shelton said. "And industries should be encouraged to create more dual- gene plants."
Source: Xinhua

Taken from: http://english.people.com.cn/200506/19/eng20050619_191053.html

Environment!!!!!BT Toxins that are leaking into the Soil

2007-07-19T15:16:00.000-07:00

THE TIMES THURSDAY DECEMBER 2 1999
GM crop toxin is leaking into the soil
BV NICK NUTTALL ENVIRONMENT CORRESPONDENT
SOME genetically modified crops are leaking powerful toxins from
their roots into the soil, scientists have found.
Researchers described the findings as "surprising and unexpected",
raising fresh fears about the environmental impact of such crops.
Companies have modified plants to produce poisons or toxins to combat
the pests that eat their stems and leaves. But the discovery that the
same plants are also leaking toxins into the soil has not, until now,
been considered an issue.
It will raise fears among some scientists, regulators and
environmental groups that beneficial soil organisms might be killed
and that in- sects living in the soil might become resistant to the
poisons.
The findings, published to- day in Nature, have been re- leased by a
team at the Univer- sity of New York that has been studying the roots
of GM maize.
Several crops, from maize, to corn and potatoes, have been genetically
modified to kill insect pests using a gene derived from a bacterium
called Bacillus thuringiensis (BT). In the United States 15 million
acres of corn modified with the BT gene were planted in 1998 or just
under 20 per
cent of the total crop. GM maize has also been planted in Europe
although the acreage is far smaller.
Concerns about the impact of such crops on the environ- ment were
triggered earlier in the year when it was found that monarch
butterflies had died after feeding on milk- weed dusted with pollen
from GM corn.
Other research found that lacewings that had fed on corn borers reared
on BT corn had also died, raising concerns that such crops are harming
more than just pests.
Professor Guenther Stozky, of New York University's labo- ratory of
microbial ecology, who has led the research, said yesterday that the
monarch re- search showed that the toxin was released from the pollen.
"Now we have found it is also continuously released from the roots
into the soil. The fact that the toxin is re- leased from the roots
was unex- pected," he said.
Professor Stozky said that the BT toxin was a large pro- tein molecule
which they had considered too large to cross the root membrane.
During the research, the team grew GM seedlings in the laboratory for
25 days. Each plant produced on average 105 microgrammes of pro- tein
and this was tested against larvae of the tobacco hornworm. Up to 95
per cent of the larvae died after five days with 50 per cent killed at
a dose of just 5.2 micro- grammes of protein.
Because the roots are constantly leaking the toxin, there is also the
risk that pests in the soil might rapidly become immune to the poison
triggering new, resistant, strains.
Biotechnology companies are likely to claim that, because the
bacterium from which the BT gene is taken, is found in the soil the
toxin is naturally part of the environment underground. But Professor
Stozky challenged such assertions, claiming that the bacterium was not
prevalent in the soil.
Dr Doug Parr, of Greenpeace said that the findings underscored the
"ability of GM crops to wrong-foot their creators and produce
unexpected and unwanted effects".
Dr Penny Hirsch, a soil expert at lACR-Rothamsted in Harpenden,
Hertfordshire, said yesterday that the findings were "interesting" but
added that field tests were needed to see whether the effects in the
laboratory were happening in the real world.
Taken from: http://www.gene.ch/gentech/1999/Dec/msg00018.html

WHat are goverment doing on GM foods?

2007-06-11T16:43:00.000-07:00

What are the government role in GM foods?

Governments around the world are hard at work to establish a regulatory process to monitor the effects of and approve new varieties of GM plants. Yet depending on the political, social and economic climate within a region or country, different governments are responding in different ways.
In Japan, the Ministry of Health and Welfare has announced that health testing of GM foods will be mandatory as of April 200136, 37. Currently, testing of GM foods is voluntary. Japanese supermarkets are offering both GM foods and unmodified foods, and customers are beginning to show a strong preference for unmodified fruits and vegetables.
India's government has not yet announced a policy on GM foods because no GM crops are grown in India and no products are commercially available in supermarkets yet38. India is, however, very supportive of transgenic plant research. It is highly likely that India will decide that the benefits of GM foods outweigh the risks because Indian agriculture will need to adopt drastic new measures to counteract the country's endemic poverty and feed its exploding population.
Some states in Brazil have banned GM crops entirely, and the Brazilian Institute for the Defense of Consumers, in collaboration with Greenpeace, has filed suit to prevent the importation of GM crops39,. Brazilian farmers, however, have resorted to smuggling GM soybean seeds into the country because they fear economic harm if they are unable to compete in the global marketplace with other grain-exporting countries.
In Europe, anti-GM food protestors have been especially active. In the last few years Europe has experienced two major foods scares: bovine spongiform encephalopathy (mad cow disease) in Great Britain and dioxin-tainted foods originating from Belgium. These food scares have undermined consumer confidence about the European food supply, and citizens are disinclined to trust government information about GM foods. In response to the public outcry, Europe now requires mandatory food labeling of GM foods in stores, and the European Commission (EC) has established a 1% threshold for contamination of unmodified foods with GM food products40.
In the United States, the regulatory process is confused because there are three different government agencies that have jurisdiction over GM foods. To put it very simply, the EPA evaluates GM plants for environmental safety, the USDA evaluates whether the plant is safe to grow, and the FDA evaluates whether the plant is safe to eat. The EPA is responsible for regulating substances such as pesticides or toxins that may cause harm to the environment. GM crops such as B.t. pesticide-laced corn or herbicide-tolerant crops but not foods modified for their nutritional value fall under the purview of the EPA. The USDA is responsible for GM crops that do not fall under the umbrella of the EPA such as drought-tolerant or disease-tolerant crops, crops grown for animal feeds, or whole fruits, vegetables and grains for human consumption. The FDA historically has been concerned with pharmaceuticals, cosmetics and food products and additives, not whole foods. Under current guidelines, a genetically-modified ear of corn sold at a produce stand is not regulated by the FDA because it is a whole food, but a box of cornflakes is regulated because it is a food product. The FDA's stance is that GM foods are substantially equivalent to unmodified, "natural" foods, and therefore not subject to FDA regulation.
The EPA conducts risk assessment studies on pesticides that could potentially cause harm to human health and the environment, and establishes tolerance and residue levels for pesticides. There are strict limits on the amount of pesticides that may be applied to crops during growth and production, as well as the amount that remains in the food after processing. Growers using pesticides must have a license for each pesticide and must follow the directions on the label to accord with the EPA's safety standards. Government inspectors may periodically visit farms and conduct investigations to ensure compliance. Violation of government regulations may result in steep fines, loss of license and even jail sentences.
As an example the EPA regulatory approach, consider B.t. corn. The EPA has not established limits on residue levels in B.t corn because the B.t. in the corn is not sprayed as a chemical pesticide but is a gene that is integrated into the genetic material of the corn itself. Growers must have a license from the EPA for B.t corn, and the EPA has issued a letter for the 2000 growing season requiring farmers to plant 20% unmodified corn, and up to 50% unmodified corn in regions where cotton is also cultivated41. This planting strategy may help prevent insects from developing resistance to the B.t. pesticides as well as provide a refuge for non-target insects such as Monarch butterflies.
The USDA has many internal divisions that share responsibility for assessing GM foods. Among these divisions are APHIS, the Animal Health and Plant Inspection Service, which conducts field tests and issues permits to grow GM crops, the Agricultural Research Service which performs in-house GM food research, and the Cooperative State Research, Education and Extension Service which oversees the USDA risk assessment program. The USDA is concerned with potential hazards of the plant itself. Does it harbor insect pests? Is it a noxious weed? Will it cause harm to indigenous species if it escapes from farmer's fields? The USDA has the power to impose quarantines on problem regions to prevent movement of suspected plants, restrict import or export of suspected plants, and can even destroy plants cultivated in violation of USDA regulations. Many GM plants do not require USDA permits from APHIS. A GM plant does not require a permit if it meets these 6 criteria: 1) the plant is not a noxious weed; 2) the genetic material introduced into the GM plant is stably integrated into the plant's own genome; 3) the function of the introduced gene is known and does not cause plant disease; 4) the GM plant is not toxic to non-target organisms; 5) the introduced gene will not cause the creation of new plant viruses; and 6) the GM plant cannot contain genetic material from animal or human pathogens (see http://www.aphis.usda.gov:80/bbep/bp/7cfr340 ).
The current FDA policy was developed in 1992 (Federal Register Docket No. 92N-0139) and states that agri-biotech companies may voluntarily ask the FDA for a consultation. Companies working to create new GM foods are not required to consult the FDA, nor are they required to follow the FDA's recommendations after the consultation. Consumer interest groups wish this process to be mandatory, so that all GM food products, whole foods or otherwise, must be approved by the FDA before being released for commercialization. The FDA counters that the agency currently does not have the time, money, or resources to carry out exhaustive health and safety studies of every proposed GM food product. Moreover, the FDA policy as it exists today does not allow for this type of intervention.
(Taken from: http://www.csa.com/discoveryguides/gmfood/overview.php)

WHat is the CSIRO doing in relation to GM foods?

2007-06-11T16:42:00.000-07:00

Assessing the Impact of GMOs on the Environment
CSIRO researchers are exploring how a broad range of GMOs might impact on the environment at the landscape or ecosystem level
CSIRO is committed to examining the effects of GMOs (genetically modified organisms) on the environment.
This commitment was formalised in 2000, when a three-year project began, involving scientists from seven Divisions. This project was one of the activities carried out under the government’s National Biotechnology Strategy. Environment Australia provided part of the $3 million funding.
The aim is to explore how a broad range of GMOs might impact on the environment at the landscape or ecosystem level. It aimed to build research capabilities in this area and develop research tools to assess potential environmental risks of GMO uptake. Eventually the scientists hope to transfer the best of these tools to the regulators to help them in assessing whether new GMOs should be released.
Ecological risk assessment at the landscape level is a new research field worldwide and most of the work of the original project was aimed at establishing a better understanding of the scale and nature of issues relevant to the Australian environment.
The research team has worked on several GMOs for their case studies. These are:
Bt-cotton in large-scale crops
GM clover for temperate pastures
Plants containing viral sequences
Mice plague control.
Amongst the findings so far are the facts that:
Bt-cotton plants express Bt-toxin in small amounts through both their leaves and roots. The majority of this toxin degrades within 2-4 weeks of plant biomass being incorporated into leaf decomposition in soil. This means that in general, Bt-toxin from GM cotton will not have an adverse effect on the environment. However, research into the impact of the minority of Bt-toxin that may persist in the soil has not been done yet
There is an apparent increase in fungi and fungal spores found on Bt-cotton residues compared to non-Bt resides. We do not know yet whether this increase, if real, is good, neutral or harmful to the environment
GM subterranean clover poses little threat to native grasslands in Australia. It will survive less well than non-GM clover if it strays into native perennial grasslands but it may survive better in more disturbed, annual grassland communities
To help focus the continuing research a Joint Reference group has been established by CSIRO, the Department of the Environment and Heritage and the Office of the Gene Technology Regulator to identify priority areas for risk assessment research and seek out realistic case studies on which to test new methods.
The assessment team has also advised the Federal Government on the relevance to Australia of overseas studies of environmental impact of GMOs. The first of these has been farm-scale trials in the UK, reported in 2003.
(Taken from: http://www.csiro.au/pubgenesite/faqs.htm)

REsponsible for ensuring GM crops not causing harm to environment

2007-06-11T16:41:00.000-07:00

The Commonwealth Health portfolio has responsibility for overseeing genetically modified organisms (GMOs) in Australia and does this through the Office of the Gene Technology Regulator (OGTR).
Before any new GM crops are brought to market they are thoroughly evaluated for environmental safety on a case-by-case basis by the regulator. The OGTR is required to seek advice and comments from the Minister for the Environment, the public, scientists and various regulatory agencies, including Food Standards Australia New Zealand.
(Taken from: http://www.csiro.au/pubgenesite/faqs.htm)

Environmental Issues Of GM foods

2007-06-11T16:37:00.000-07:00

Environmental controverisies on GM foods

Advantages:

-Friendly" bioherbicides and bioinsecticides
-Conservation of soil, water, and energy
-Bioprocessing for forestry products
-Better natural waste management
-More efficient processing

(Taken from : http://www.ornl.gov/sci/techresources/Human_Genome/elsi/gmfood.shtml)

· Pest resistance Crop losses from insect pests can be staggering, resulting in devastating financial loss for farmers and starvation in developing countries. Farmers typically use many tons of chemical pesticides annually. Consumers do not wish to eat food that has been treated with pesticides because of potential health hazards, and run-off of agricultural wastes from excessive use of pesticides and fertilizers can poison the water supply and cause harm to the environment. Growing GM foods such as B.t. corn can help eliminate the application of chemical pesticides and reduce the cost of bringing a crop to market4, 5.

· Herbicide tolerance For some crops, it is not cost-effective to remove weeds by physical means such as tilling, so farmers will often spray large quantities of different herbicides (weed-killer) to destroy weeds, a time-consuming and expensive process, that requires care so that the herbicide doesn't harm the crop plant or the environment. Crop plants genetically-engineered to be resistant to one very powerful herbicide could help prevent environmental damage by reducing the amount of herbicides needed. For example, Monsanto has created a strain of soybeans genetically modified to be not affected by their herbicide product Roundup ®6. A farmer grows these soybeans which then only require one application of weed-killer instead of multiple applications, reducing production cost and limiting the dangers of agricultural waste run-off7.

(Taken from: http://www.csa.com/discoveryguides/gmfood/overview.php)

Disadvantages:

· Development of insecticide-resistant Lepidopteran insects
In any group of organism that are given a poison (like bacteria and antibiotics), there are bound to be a few who survive the poison due to a slight genetic advantage. What happens when the ECB develops resistance to Bt and then pass their resistance on to their descendants???
EPA's Bt plan - March 2000 Refuge strategy. Growers who plant Bt hybrids must also plant refuges (blocks of non-Bt corn). The refuge supplies a source of moths that are not exposed to Bt corn to mate with those that have resistance to Bt. That mating should delay resistance for 20 - 50 years.
(Taken from: http://www.biology.iupui.edu/biocourses/N100/2k3agbio.html)

Phytoremediation Not all GM plants are grown as crops. Soil and groundwater pollution continues to be a problem in all parts of the world. Plants such as poplar trees have been genetically engineered to clean up heavy metal pollution from contaminated soil18.
Drought tolerance/salinity tolerance As the world population grows and more land is utilized for housing instead of food production, farmers will need to grow crops in locations previously unsuited for plant cultivation. Creating plants that can withstand long periods of drought or high salt content in soil and groundwater will help people to grow crops in formerly inhospitable places11, 12.

· Unintended harm to other organisms Last year a laboratory study was published in Nature21 showing that pollen from B.t. corn caused high mortality rates in monarch butterfly caterpillars. Monarch caterpillars consume milkweed plants, not corn, but the fear is that if pollen from B.t. corn is blown by the wind onto milkweed plants in neighboring fields, the caterpillars could eat the pollen and perish. Although the Nature study was not conducted under natural field conditions, the results seemed to support this viewpoint. Unfortunately, B.t. toxins kill many species of insect larvae indiscriminately; it is not possible to design a B.t. toxin that would only kill crop-damaging pests and remain harmless to all other insects. This study is being reexamined by the USDA, the U.S. Environmental Protection Agency (EPA) and other non-government research groups, and preliminary data from new studies suggests that the original study may have been flawed22, 23. This topic is the subject of acrimonious debate, and both sides of the argument are defending their data vigorously. Currently, there is no agreement about the results of these studies, and the potential risk of harm to non-target organisms will need to be evaluated further.

· Reduced effectiveness of pesticides Just as some populations of mosquitoes developed resistance to the now-banned pesticide DDT, many people are concerned that insects will become resistant to B.t. or other crops that have been genetically-modified to produce their own pesticides.

· Gene transfer to non-target species Another concern is that crop plants engineered for herbicide tolerance and weeds will cross-breed, resulting in the transfer of the herbicide resistance genes from the crops into the weeds. These "superweeds" would then be herbicide tolerant as well. Other introduced genes may cross over into non-modified crops planted next to GM crops. The possibility of interbreeding is shown by the defense of farmers against lawsuits filed by Monsanto. The company has filed patent infringement lawsuits against farmers who may have harvested GM crops. Monsanto claims that the farmers obtained Monsanto-licensed GM seeds from an unknown source and did not pay royalties to Monsanto. The farmers claim that their unmodified crops were cross-pollinated from someone else's GM crops planted a field or two away. More investigation is needed to resolve this issue.
There are several possible solutions to the three problems mentioned above. Genes are exchanged between plants via pollen. Two ways to ensure that non-target species will not receive introduced genes from GM plants are to create GM plants that are male sterile (do not produce pollen) or to modify the GM plant so that the pollen does not contain the introduced gene24, 25, 26. Cross-pollination would not occur, and if harmless insects such as monarch caterpillars were to eat pollen from GM plants, the caterpillars would survive.
Another possible solution is to create buffer zones around fields of GM crops27, 28, 29. For example, non-GM corn would be planted to surround a field of B.t. GM corn, and the non-GM corn would not be harvested. Beneficial or harmless insects would have a refuge in the non-GM corn, and insect pests could be allowed to destroy the non-GM corn and would not develop resistance to B.t. pesticides. Gene transfer to weeds and other crops would not occur because the wind-blown pollen would not travel beyond the buffer zone. Estimates of the necessary width of buffer zones range from 6 meters to 30 meters or more30. This planting method may not be feasible if too much acreage is required for the buffer zones.
(Taken from: http://www.csa.com/discoveryguides/gmfood/overview.php)

· GM crops changing agricultural practices
(eg. Herbicides torelrant crops in intensive agricultural farming
· Weed as habitat for birds, insects and wildlife

(Taken from: http://www.doylefoundation.org/persleybnk0701b.pdf)

wHAT ARE GM FOODS?????????

2007-06-11T16:33:00.000-07:00

What are GM foods?

· GM is a special set of technologies that alter the genetic makeup of such living organisms as animals, plants, or bacteria.
· using living organisms or their components, such as enzymes, to make products that include wine, cheese, beer, and yogurt
· Combining genes from different organisms is known as recombinant DNA technology, and the resulting organism is said to be "genetically modified," "genetically engineered," or "transgenic."

(Taken from:
http://www.ornl.gov/sci/techresources/Human_Genome/elsi/gmfood.shtml)

· genetically modified food crops included virus-resistant squash, a potato variant that included an organic pesticide called Bt (NB: the EPA classified the Bt potato as a pesticide, but required no labeling), strains of canola, soybean, corn and cotton engineered by Monsanto to be immmune to their popular herbicide Roundup, and Bt corn.
(Taken from: Wikipedia)

· Genetic engineering, on the other hand, can create plants with the exact desired trait very rapidly and with great accuracy
(taken from:
http://www.csa.com/discoveryguides/gmfood/overview.php)

HACCP discussion information!!!

2007-05-20T22:09:00.000-07:00

AVOIDING FOOD CONTAMINATION

Food safety is a shared responsibility of everyone involved in the food chain from farm to fork. This includes primary producers, food companies, establishments which serve food, and consumers.

At the farm level, there are critical control points at every stage in animal rearing and crop agriculture where contamination of produce can be minimised by following good practices. After slaughtering, for example, inspections are carried out to separate diseased meat from healthy meat, However, even healthy animals can carry human pathogens and their meat can also become contaminated during slaughtering. These pathogens can be difficult to eradicate. Fresh fruits, vegetables and herbs can also become contaminated if they are fertilised with animal manure or come into contact with impure water. Crop plants may be treated to destroy pathogens - for example using biocidal washes - but such treatments are not always carried out.

At the food manufacturer level, the majority of companies have in-house quality assurance systems to ensure the safe production of food. Throughout the European Union, there are moves towards less prescriptive regulation and greater emphasis on industry responsibility. Measures currently used to help prevent contaminated food from reaching the consumer include:
· Using good quality raw materials from assured suppliers.
· Following Good Manufacturing Practices. Using management systems which allow the identification, monitoring and control of hazards during production, processing and sale of food.
· Providing training programmes for all food industry personnel. Carrying out research on pathogens and how best to control them.
·Exchanging information on food safety.

At the next level of the food chain from farm to fork, many foodborne diseases occur either as a result of mishandling in catering establishments or in the home.
A number of simple rules are recommended by the World Health Organization to ensure the safe preparation of foods:
·Avoid contact between raw and cooked foods, to reduce the risk of cross-contamination. Wash hands before handling and after handling raw foods, to mimalise possible contamination.
·Cook food thoroughly in order to kill any microbes present. All parts of the food should reach a temperature of at least 70 degrees Celsius.
·Cool cooked foods as quickly as possible and then refrigerate. This slows down or stops microbial growth, which occurs best at 10-60 degrees Celsius.
·Reheat cooked foods thoroughly, to kill tiny microbes which may have developed during storage.
.Keep all kitchen surfaces clean to prevent cross-contamination. Protect foods from insects, rodents and other animals which may carry pathogenic

Hey guys i think this not bad for HACCP discussion as it talk about food contamination and also the danger zone of temperature that we can include in.can browse through the web at

http://www.eufic.org/article/en/page/RARCHIVE/expid/review-foodborne-illness/

What can i do to prevent FoodBorn Illness????

2007-05-20T22:03:00.000-07:00

The Core Four Practices

Clean: Wash Hands and Surfaces Often

Bacteria can be spread throughout the kitchen and get onto hands, cutting boards, utensils, counter tops and food.

To Fight BAC!® always:
Wash your hands with warm water and soap for at least 20 seconds before and after handling food and after using the bathroom, changing diapers and handling pets.
Wash your cutting boards, dishes, utensils, and counter tops with hot soapy water after preparing each food item and before you go on to the next food.
Consider using paper towels to clean up kitchen surfaces. If you use cloth towels wash them often in the hot cycle of your washing machine.
Rinse fresh fruits and vegetables under running tap water, including those with skins and rinds that are not eaten.
Rub firm-skin fruits and vegetables under running tap water or scrub with a clean vegetable brush while rinsing wtih running tap water.

Separate: Don't Cross-Contaminate!

Cross-contamination is how bacteria can be spread. When handling raw meat, poultry, seafood and eggs, keep these foods and their juices away from ready-to-eat foods. Always start with a clean scene -- wash hands with warm water and soap. Wash cutting boards, dishes, countertops and utensils with hot soapy water.
Separate raw meat, poultry, seafood and eggs from other foods in your grocery shopping cart, grocery bags and in your refrigerator.
Use one cutting board for fresh produce and a separate one for raw meat, poultry and seafood.
Never place cooked food on a plate that previously held raw meat, poultry, seafood or eggs.

Cook: Cook to Proper Temperatures

Food is safely cooked when it reaches a high enough internal temperature to kill the harmful bacteria that cause foodborne illness. Use a food thermometer to to measure the internal temperature of cooked foods. Use a food thermometer which measures the internal temperature of cooked meat, poultry and egg dishes, to make sure that the food is cooked to a safe internal temperature.
Cook roasts and steaks to a minimum of 145°F. All poultry should reach a safe minimum internal temperature of 165°F as measured with a food thermometer. Check the internal temperature in the innermost part of the thigh and wing and the thickest part of the breast with a food thermometer.
Cook ground meat, where bacteria can spread during grinding, to at least 160°F. Information from the Centers for Disease Control and Prevention (CDC) links eating undercooked ground beef with a higher risk of illness. Remember, color is not a reliable indicator of doneness. Use a food thermometer to check the internal temperature of your burgers.
Cook eggs until the yolk and white are firm, not runny. Don't use recipes in which eggs remain raw or only partially cooked.
Cook fish to 145°F or until the flesh is opaque and separates easily with a fork.
Make sure there are no cold spots in food (where bacteria can survive) when cooking in a microwave oven. For best results, cover food, stir and rotate for even cooking. If there is no turntable, rotate the dish by hand once or twice during cooking.
Bring sauces, soups and gravy to a boil when reheating. Heat other leftovers thoroughly to 165°F.

Chill: Refrigerate Promptly!

Refrigerate foods quickly because cold temperatures slow the growth of harmful bacteria. Do not over-stuff the refrigerator. Cold air must circulate to help keep food safe. Keeping a constant refrigerator temperature of 40°F or below is one of the most effective ways to reduce the risk of foodborne illness. Use an appliance thermometer to be sure the temperature is consistently 40°F or below. The freezer temperature should be 0°F or below.
Refrigerate or freeze meat, poultry, eggs and other perishables as soon as you get them home from the store.
Never let raw meat, poultry, eggs, cooked food or cut fresh fruits or vegetables sit at room temperature more than two hours before putting them in the refrigerator or freezer (one hour when the temperature is above 90°F).
Never defrost food at room temperature. Food must be kept at a safe temperature during thawing. There are three safe ways to defrost food: in the refrigerator, in cold water, and in the microwave. Food thawed in cold water or in the microwave should be cooked immediately.
Always marinate food in the refrigerator.
Divide large amounts of leftovers into shallow containers for quicker cooling in the refrigerator.
Use or discard refrigerated food on a regular basis. Check the Cold Storage Chart for optimum storage times.

By: http://www.fightbac.org/content/view/169/97/

Summary of foodborn illness that are related to meat and poultry

2007-05-20T21:31:00.000-07:00

Common food born illness that are related to Meat and Poultry:

Bacterim:Salmonella Species (salmonellosis)
Principal symptoms: Diarrhea, abdominal Pain, Chills, Fever, vomitting
TYpical foods: Raw and undercooked eggs, raw milk, meat and poultry

Bacterium: Camplyobacter jejuni (camplyobacteriosis)
Principal symptoms: Diarrhea, abdominal Pain, fever, nausea, vomitting
Typical foods: Infected food source animals

Bacterium:Clostridium perfringens
Typical Symptoms: Diarrhea, cramps, rarely nausea and vomitting
TYpical foods: cooked meat and poultry

Bacterium: Bacillus Cereus
Typical symptoms: Diarrhea, cramps, occasional vomitting
Typical foods: meat products, soups, sauces, vegetables

Parasites

Bacterium: Trichnella spirlis ( trichnosis)
Typical symptoms: muscle pain, swollen eyelids, fever,sometimes death
Typical foods: raw, undercooked pork

Bacterium: Taenia Saginata
Typical Symptoms: worm segments in tools, sometimes "cycticercosis" of muscle, organs, hear,or brain
Typical foods: Raw or undercoooked pork

Bacterium: Toxoplasma gondi
Typical symptoms:fetal abnormality, or death
Typical foods: raw or undercooked meats of carnivarious

Bacteria that cause Foodborn illness

2007-05-20T21:21:00.000-07:00

Common Sources of Foodborne Illness

Sources of illness: Raw and undercooked meat and poultry
Symptoms: Abdominal pain, diarrhea, nausea, and vomiting
Bacteria: Campylobacter jejuni, E. coli O157:H7, L. monocytogenes, Salmonella

Sources of illness: Raw foods; unpasteurized milk and dairy products, such as soft cheeses
Symptoms: Nausea, vomiting, fever, abdominal cramps, and diarrhea
Bacteria: L. monocytogenes, Salmonella, Shigella, Staphylococcus aureus, C. jejuni

Sources of illness: Raw and undercooked eggs. Raw eggs are often used in foods such as homemade hollandaise sauce, caesar and other salad dressings, tiramisu, homemade ice cream, homemade mayonnaise, cookie dough, and frostings.
Symptoms: Nausea, vomiting, fever, abdominal cramps, and diarrhea
Bacterium: Salmonella enteriditis

Sources of illness: Raw and undercooked shellfish
Symptoms: Chills, fever, and collapse
Bacteria: Vibrio vulnificus, Vibrio parahaemolyticus

Sources of illness: Improperly canned goods; smoked or salted fish
Symptoms: Double vision, inability to swallow, difficulty speaking, and inability to breathe. Seek medical help right away if you experience any of these symptoms.
Bacterium: C. botulinum

Sources of illness: Fresh or minimally processed produce; contaminated water
Symptoms: Bloody diarrhea, nausea, and vomiting
Bacteria: E. coli O157:H7, L. monocytogenes, Salmonella, Shigella, Yersinia enterocolitica, viruses, and parasites

Takenfrom:http://digestive.niddk.nih.gov/ddiseases/pubs/bacteria/index.htm

For more imformation on Foodborn illness you all can browse through this webby , i find it not bad from FDA.

http://www.foodsafety.gov/~dms/fsefborn.html

what is foodborn Illness?

2007-05-20T17:52:00.000-07:00

What is Foodborn Illness?

Any illness that result after the ingestion of foods
There are actually 3 types of hazards that are related to food born illness.

- Biological Hazards

-> Bacteria, molds, viruses, roundworm

-> It is classify into, infection intoxication, and intoxication.

- Chemical Hazards

-> Plant toxins

- Physical Hazards

-> Metal parts

Foods that has the higest risk of foodborn illness

2007-05-06T09:51:00.000-07:00

WHICH FOODS POSE THE GREATEST RISK?
Foods of animal origin are the primary source of many food poisoning microbes, such as Salmonella, Listeria, Campylobacter, E coli and L monocytogenes. These may occur on the live animal, and remain in the meat after slaughter. Without appropriate treatment to kill the microbes, or if conditions of hygiene or temperature control are poor, microbes may still occasionally be present in the final food product.
Foods which pose a relatively high risk of foodborne illness include:
Poultry, meat & eggs - The incidence of contamination is probably highest in poultry. Here, rapid growth in poultry production has resulted in a readily-available source of meat. However, there has been increased infection with food poisoning microbes in poultry, meat and eggs. Eggs can carry bacteria such as Salmonella enteritidis on their shells or within the egg. Salmonella infections are on the increase across Europe. An important precaution in preventing foodborne illness from poultry and eggs is thorough cooking; the World Health Organisation recommends that raw egg should be viewed as a potentially hazardous ingredient which should not be used in foods which will receive no further heat treatment.
Red meats - These can also be contaminated with pathogenic microbes, probably to a lesser extent than poultry. The process of grinding meat to make mince and burgers may spread the microbes from one source into many products. As for poultry products, red meats should be thoroughly cooked before serving.
Dairy products - Raw milk can contain various pathogens from the dairy animal or its environment. Pasteurization destroys all pathogens, and sterilisation ensures that the product is free from all microbes. Whilst pathogens are inactivated by many of the methods used to produce dairy products - including acidification and fermentation of milk - certain types may sometimes survive. Hard cheeses, yoghurt and butter are regarded as safe because of their acidity or lack of moisture, but mould-ripened soft cheeses can allow growth of Listeria monocytogenes.
Shellfish - As filter feeders which extract their diets from large volumes of water, shellfish can concentrate pathogens in their bodies. Inadequately heat-treated shellfish can cause a range of infections due to bacteria (such as Vibrio and Shigella), various parasites or viruses.
Herbs and spices - These frequently carry large numbers of bacteria such as Bacillus cereus, Clostridium perfringens and Salmonella.

Taken from: http://www.eufic.org/article/en/page/RARCHIVE/expid/review-foodborne-illness/

food born illness

2007-04-12T06:09:00.000-07:00

what is Food born illness?
A foodborne illness (also foodborne disease) is any illness resulting from the consumption of contaminated food. Although foodborne illness is commonly called food poisoning, this is often a misnomer. True food poisoning occurs when a person ingests a contaminating chemical or a natural toxin, while most cases of foodborne illness are actually food infection caused by a variety of foodborne pathogenic bacteria, viruses, prions or parasites.[1] Such contamination usually arises from improper handling, preparation, or food storage. Good hygiene practices before, during, and after food preparation can reduce the chances of contracting an illness. The action of monitoring food to ensure that it will not cause foodborne illness is known as food safety. Foodborne disease can also be caused by a large variety of toxins that affect the environment. (Taken From:http://en.wikipedia.org/wiki/Food_poisoning)

Countries that are affected by Avian Influenza(H5N1)

2007-04-04T01:01:00.000-07:00

Countries affected from 1st January2006 to 31st December2006
-Egypt
-Turkey
-Iraq
-Azerbaijan
-Thailand
-China
-Indonesia
-Cambodia
Taken from World Health Organisation:http://gamapserver.who.int/mapLibrary/

Definition of HACCP

2007-04-03T23:07:00.000-07:00

The Hazard Analysis and Critical Control Point (HACCP) method is, by definition, focused on identifying hazards which might result in consumers receiving harmful food products. HACCP was first utilized by the Pillsbury Company in 1959 to produce foods for the US space program. Since that time, HACCP has gained wide acceptance as the state-of-the-art control method for preventing biological, chemical and physical hazards from entering the human food distribution chain.
HACCP definitions and principles are based on the U.S. National Advisory Committee on Microbiological Criteria for Foods (NACMCF) HACCP System Guide. This guide is intended to assist food processors to prepare and manage a HACCP program tailored to their products, raw materials and processes.
The NACMCF Guide defines 7 Principles which are applied in sequence as follows:
Assess Hazards
Determine Critical Control Points (CCP's) for each Hazard
Determine Limits for each CCP
Establish CCP Monitoring
Establish Corrective Actions to be Taken When CCP Limits are Exceeded
Establish Record Keeping for HACCP system
Establish Procedures that Verify that the HACCP System is Working Properly
The U.S. Food and Drug Administration (FDA) and the U.S. Department of Agriculture, Food Safety and Inspection Service (FSIS) have promulgated regulations requiring the use of HACCP in the seafood, red meat and poultry industries. The FDA's seafood HACCP regulation was finalized in January 1996 while the FSIS final HACCP regulation is pending.
Taken from:HACCP,Retieved April 4,2007,from http://pera.net/Risk_HACCP.html

Avian influenza

2007-04-03T08:39:00.000-07:00

Avian Influenza is not transmissible by eating poultry or eggs that have been properly prepared. Hens infected with HPAI usually stop laying eggs as one of the first signs of illness, and the few eggs that are laid by infected hens generally would not get through egg washing and grading because the shells are weak and misshapen. Also, when there is a disruption in the egg flow checks the flow will be stopped immediately to prevent any infected egg from moving in with healthy ones. Cooking poultry, eggs, and other poultry products to the proper temperature and preventing cross-contamination between raw and cooked food is the key to food safety
Some handling practices that are recommended to prevent illness from common foodborne pathogens such as Salmonella:
Wash hands with warm water and soap for at least 20 seconds before and after handling raw poultry and eggs.
Clean cutting boards and other utensils with soap and hot water to keep raw poultry or eggs from contaminating other foods.
Cutting boards may be sanitized by using a solution of 1 tablespoon chlorine bleach and 1 gallon of water;
Cook poultry to an internal temperature of at least 165 degrees Fahrenheit. Consumers can cook poultry to a higher temperature for personal preference.
Cook eggs until the yolks and whites are firm. Use either shell eggs that have been treated to destroy Salmonella by pasteurization or another approved method, or pasteurized egg products for recipes that call for eggs that are raw or undercooked when the dish is served. Some examples of these kinds of dishes are Caesar salad dressing and homemade ice cream. Commercial mayonnaise, dressing, and sauces contain pasteurized eggs that are safe to eat.
References: What customers need to know about avian influenza,FDA.Retrieved April3, 2007,from http://www.cfsan.fda.gov/~dms/avfluqa.html#eat

hello guys!!

2007-04-01T19:39:00.000-07:00

happy today !