Protection from effects of the organophosphate insecticide, malathion on the liver and kidney of male Wistar albino rats by -tocopherol and selenium was investigated. Significantly greater (P<0.01) mean concentrations of malondialdehyde (MDA) and lesser concentrations (P<0.01) of reduced glutathione (GSH) and tissues total proteins were observed in liver and kidney of rats exposed to malathion. Activities of the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were less in livers and kidneys of rats exposed to malathion. These effects caused by exposure to malathion were reversed when rats were subsequently treated orally with 100 mg/kg b.w. tocopherol and/or 0.1 mg selenium/kg b.w. Both tocopherol and selenium (Se) reduced the concentration of MDA, and increased concentration of total proteins and reduced glutathione and mean activities of SOD, CAT and GPx, to levels that were not significantly different from unexposed, control rats, previous to exposure to malathion. Selenium was significantly (P<0.05) more effective at recovering activities of SOD and GPx in liver and kidney of malathion treated rats than wastocopherol, whereas, -tocopherol was significantly (P<0.05) more effective at recovering activities of CAT in liver and kidney than was Se. Both -tocopherol and Se were effective in alleviating oxidative damage in liver and kidney of rats caused by malathion.

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ABSTRACT. Twelve species from six fungal genera were found to be associated with corn (Zea mays L.) grain samples collected from three main regions of Saudi Arabia. The average frequencies of the most common genera were Aspergillus (11.4%), Fusarium (9.5%), Penicillium (5.1%), and Alternaria (5.8%). Fifteen isolates of Aspergillus flavus were screened by HPLC for their ability to produce aflatoxins (AF). The percentage of aflatoxigenic A. flavus isolates was 53%. Eight isolates produced AF, at concentrations ranging 0.7-2.9 ppb. Random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) molecular markers were used to genetically characterize isolates of A. flavus and to discriminate between the aflatoxigenic and non-aflatoxigenic isolates. RAPD and ISSR analysis revealed a high level of genetic diversity in the A. flavus population, which was useful for genetic characterization. The clustering in the RAPD and ISSR dendrograms obtained was unrelated to geographic origin. The RAPD and ISSR markers could not discriminate between aflatoxigenic and non-aflatoxigenic isolates, but the ISSR primers were somewhat better.

ABSTRACT. Twelve species belonging to six fungal genera were found to be associated with wheat (Triticum aestivum L.) grain samples collected from three main regions in Saudi Arabia. The most common genera (average frequency) were Aspergillus (14.3%), Fusarium (29.1%), Penicillium (9.3%), and Alternaria (8.2%). Nineteen isolates of Aspergillus flavus were screened for their ability to produce aflatoxins using HPLC. Thirteen isolates produced aflatoxins ranging from 0.5 to 2.6 µg/kg. Inter-simple sequence repeats (ISSR), and random amplified polymorphic DNA (RAPD) molecular markers were used, with the aim of genetically characterizing strains of A. flavus to discriminate between aflatoxigenic and non-aflatoxigenic isolates. RAPD and ISSR analysis revealed a high level of genetic diversity in the A. flavus population, useful for genetic characterization. Clustering based on RAPD and ISSR dendograms was unrelated to geographic origin. RAPD and ISSR markers were not suitable to discriminate aflatoxigenic and nonaflatoxigenic isolates, but ISSR primers were better compared to RAPD.