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A review on biological control and metabolism of aflatoxin.

The series of events that led to the discovery of aflatoxin as a potent carcinogen, its biosynthesis, mechanism of action, structure-function relationship provide interesting insight into the economical and technological factors involved in the development of an effective control measure for the toxin. Scientists all over the world are making continuous efforts to explore a generalized process of detoxification, which can bring down the toxin content in heterogenous commodities to a threshold level. In this article biological control methods with special emphasis on in vivo and in vitro enzymatic detoxification of aflatoxin have been reviewed. Future areas of research involving large-scale enzymatic detoxification and modified atmosphere storage are also discussed.

Aflatoxins↗

The contribution of endogenous opioids to food reward is dependent on sex and background strain.

Complex behaviors such as those associated with reward to unconditioned positive reinforcers are polygenic processes. In studies using genetically modified mice specific for the endogenous opioid systems an observed phenotype in a complex behavior is likely to be dependent on interacting genes which, in inbred mouse lines, influence that phenotype. To address this issue we examined operant responding for palatable food reinforcers in mice lacking the expression of beta-endorphin, enkephalin or both peptides congenic to two different genetic backgrounds; C57BL/6J and DBA/2J. These two inbred strains were chosen because their endogenous opioid states differ and they respond differently to exogenous opioids in many behavioral assays. We found that wildtype and mutant C57BL/6J mice acquired operant responding for food reinforcers faster than DBA/2J mice, regardless of their opioid genotype. Although wildtype DBA/2J mice had a significant deficit in acquisition of bar-pressing behavior to reach a pre-established performance criterion, no subsequent deficit was observed under two different schedules of reinforcement. Additionally, we found that mice lacking enkephalin had decreased motivation to bar press for palatable food reinforcers under a progressive ratio regardless of sex or background strain. In contrast, the only subset of beta-endorphin-deficient mice that had decreased motivation to bar press under a progressive ratio was males on the C57BL/6J background. Of the two classical endogenous opioid peptides with preferential activation of the mu opioid receptor, the knockout models would suggest that enkephalins play a more consistent role than beta-endorphin in mediating the motivation for food reward when tested under a progressive ratio.

Animals↗

Genetically modified plants and human health risks: Can additional research reduce uncertainties and increase public confidence?

So long as the risks to human health from transgenic plants remain potential rather than actual, and, in any event, appear lower than those from traditional plant breeding, hazard assessment need not be extensive. However, in view of current public attitudes to transgenic plants, it is necessary that those tests that are required, be based on logic, on sound science, and in accordance with the best scientific methodology. This is particularly the case with testing for food allergenicity. Current testing is largely indirect and based on comparisons with other known food allergens. Development of direct tests that involve interaction between the actual transgenic protein in question and the immune system is essential if confidence in the regulatory system is to be restored.

Food Hypersensitivity↗

How safe is GM food?

Explore the source record for details and available documents.

Consumer Product Safety↗

Stability of recombinant human alpha-1-antitrypsin produced in rice in infant formula.

Human milk contains several biologically active proteins that benefit the breast-fed infant. In order to survive in the gastrointestinal tract, these proteins need to be protected against proteolysis. Since human milk contains relatively high concentrations of alpha-1-antitrypsin (AAT), we have expressed recombinant AAT in rice to explore the possibility of supplementing infant formula with this protein. The stability of recombinant AAT was examined by biochemical and functional assays, such as SDS-PAGE, Western blotting, ELISA, elastase and trypsin inhibition, following exposure to heat, low pH, and in vitro digestion, conducted in both phosphate buffered saline and infant formula. Native AAT is resistant to acidic environments down to pH 2 for 1 h and can withstand in vitro digestion modeled after conditions in the infant gut. Recombinant AAT is nearly as resistant as the native form in buffer, and is equally resilient in formula. Heat treatments (60 degrees C for 15 min, 72 degrees C for 20 sec, 85 degrees C for 3 min, and 137 degrees C for 20 sec) revealed that recombinant AAT is not as stable as native AAT in buffer, particularly at higher temperatures. While significantly less recombinant AAT is detected by ELISA after heating in formula, addition of bile extract can restore epitopes resulting in higher concentrations, suggesting protein aggregation that may not affect AAT activity. This study shows that recombinant AAT may survive the conditions of the infant stomach and duodenum and affect protein digestion in the infant small intestine.

Blotting, Western↗

Enhancement of the primary flavor compound methional in potato by increasing the level of soluble methionine.

The primary flavor compound in potato, methional, is synthesized from methionine by the Strecker degradation reaction. A major problem associated with potato processing is the loss of methional. Methional or its precursor, methionine, is not added back during potato processing due to high costs of production. A novel approach to enhance the methional level in processed potato would be to increase the production of its precursor, soluble methionine (Met). Cystathionine gamma-synthase (CGS) is a key enzyme regulating methionine biosynthesis in plants. To increase the level of soluble methionine in potato, Arabidopsis thaliana CGS cDNA was introduced under transcriptional control of the cauliflower mosaic virus 35S promoter into Russet Burbank potato by Agrobacterium-mediated transformation. Ten different transgenic potato lines (CGS1-10) were analyzed. Immunoblot analysis demonstrated that Arabidopsis CGS is expressed in the leaves, tubers, and roots of transgenic potato plants. CGS enzymatic activity was higher in the leaves and roots of the transgenic potato lines compared to the wild-type potato. Methionine levels in the leaves, roots and tubers of transgenic potato lines were enhanced as high as 6-fold compared to those in wild type potato plants. The methional level in baked tubers of field-grown transgenic potato lines was increased between 2.4- and 4.4-fold in lines CGS1, CGS2, and CGS4. The increase observed in methional levels correlated with the soluble methionine level in the tubers from the same lines measured before processing. These results provide the first evidence that the methional level can be enhanced in processed potatoes by increasing the production of its precursor, methionine.

Aldehydes↗

Lower fumonisin mycotoxin levels in the grain of Bt corn grown in the United States in 2000-2002.

Fumonisins were monitored in corn grain collected from Bt hybrids grown in 107 locations across the United States in 2000-2002. Bt corn hybrids contain the Cry1Ab protein from Bacillus thuringiensis that controls European corn borers and other stalk-boring pests. Fumonisin levels were frequently lower in grain from Bt hybrids grown in field trials under conditions of natural (FACT trials) or manual insect infestation (university trials). Over three years of FACT trials, there were 126/210 comparisons when fumonisin levels in grain from control hybrids were >2 ppm, exceeding U.S. FDA guidance levels of 2 ppm for human food. Grain from Bt hybrids was at or below 2 ppm of fumonisins for 58 of the 126 comparisons. The use of Bt hybrids can increase the percentage of corn grain that would be suitable for use in food and feed.

Bacillus thuringiensis Toxins↗