Aflatoxin in corn new perspectives

Preharvest contamination of com (Zea mays L.) with aflatoxin, a metabolite produced by the fungus Aspergillus flavus Link: Fr., is a recurrent problem in the southeastern United States, but occasional serious outbreaks also occur in the Midwest Com Belt (21). Aflatoxins are recognized as potent hepatotoxins and carcinogens, causing mortality or reducing the productivity of farm animals (89). Aflatoxin-contaminated foodstuffs also have been associated with increased incidence of liver cancer in humans (39). In com-producing regions, the economic impact from yield loss is not very large, but A. flavus contaminates the grain with aflatoxin. Fungal toxins reduce the value of grain as an animal feed and devalue it as an export commodity (74). Any strategy that reduces the extent of aflatoxin contamination of com will result in a safer and more valuable food supply for humans and animals. Plant pathologists and com breeders have thus far been unable to identify com genotypes with substantial resistance to aflatoxin contamination. On ears in the field, A. flavus grows saprophytically on the remains of kernels damaged by insects or birds. These damaged kernels can become contaminated with substantial quantities of aflatoxin (i.e., to as much as 300,000-600,000 ppb). Aflatoxin also accumulates (to as much as 4,000 ppb) in many of the adjacent intact kernels. It does not take a large quantity of these aflatoxin-contaminated kernels to contaminate bulk grain with \u3e20 ppb aflatoxin. At present, the only reliable method for preventing aflatoxin from entering the food chain has been the detection and segregation of aflatoxin-contaminated produce

The All-Data-Based Evolutionary Hypothesis of Ciliated Protists with a Revised Classification of the Phylum Ciliophora (Eukaryota, Alveolata)

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What can comparative genomics tell us about species concepts in the genus Aspergillus?

Understanding the nature of species” boundaries is a fundamental question in evolutionary biology. The availability of genomes from several species of the genus Aspergillus allows us for the first time to examine the demarcation of fungal species at the whole-genome level. Here, we examine four case studies, two of which involve intraspecific comparisons, whereas the other two deal with interspecific genomic comparisons between closely related species. These four comparisons reveal significant variation in the nature of species boundaries across Aspergillus. For example, comparisons between A. fumigatus and Neosartorya fischeri (the teleomorph of A. fischerianus) and between A. oryzae and A. flavus suggest that measures of sequence similarity and species-specific genes are significantly higher for the A. fumigatus - N. fischeri pair. Importantly, the values obtained from the comparison between A. oryzae and A. flavus are remarkably similar to those obtained from an intra-specific comparison of A. fumigatus strains, giving support to the proposal that A. oryzae represents a distinct ecotype of A. flavus and not a distinct species. We argue that genomic data can aid Aspergillus taxonomy by serving as a source of novel and unprecedented amounts of comparative data, as a resource for the development of additional diagnostic tools, and finally as a knowledge database about the biological differences between strains and species

The Role of Repetitive Negative Thoughts in the Vulnerability for Emotional Problems in Non-Clinical Children

The current study examined the role of repetitive negative thoughts in the vulnerability for emotional problems in non-clinical children aged 8–13 years (N = 158). Children completed self-report questionnaires for assessing (1) neuroticism and behavioral inhibition as indicators of general vulnerability (2) worry and rumination which are two important manifestations of repetitive negative thoughts, and (3) emotional problems (i.e., anxiety, depression, and sleep difficulties). Results demonstrated that there were positive correlations between measures of general vulnerability, repetitive negative thoughts, and emotional problems. Further, support was found for a model in which worry and rumination acted as partial mediators in the relation between neuroticism and symptoms of anxiety and depression. In the case of sleep difficulties, no evidence was obtained for such a mediation model. In fact, data suggested that sleeping difficulties are better conceived as an epiphenomenon of high symptom levels of anxiety and depression or as a risk factor for the development of other types of psychopathology. Finally, besides neuroticism, the temperamental trait of behavioral inhibition appeared to play a unique direct role in the model predicting anxiety symptoms but not in the models predicting depressive symptoms or sleep difficulties. To conclude, the current findings seem to indicate that worry and rumination contribute to children’s vulnerability for anxiety and depression

Incidence of post-harvest disease and airborne fungal spores in a vegetable market

The sampling of bioaerosols has been carried out using a Rotorod sampler as well as by exposing culture plates. The screening of some common vegetables was also done for the isolation of fungi as market pathogens to study post-harvest diseases. Altogether, fifty nine fungal spore types and 78 species of 33 genera belonging to different groups were recorded respectively on the rotorod strips and on exposed Petri dishes. Many saprophytic and pathogenic fungi were found to be associated with sampled vegetables from the market. In all forty-six fungal species belonging to 26 genera were recovered from five varieties of vegetables collected from the same market. The most dominant forms of fungi were of Aspergillus followed by Cladosporium, Penicillium, Alternaria, Fusarium, Curvularia, Trichoderma, and Rhizopus. Aspergillus niger, A. flavus, A. fumigatus, Penicillium spp. and Cladosporium herbarum, found to be dominant during the period of investigation. Important mycotoxin-producing fungi such as A. flavus, A. fumigatus and Fusarium moniliforme were isolated from the vegetables collected from the market

Aflatoxin in corn new perspectives

Preharvest contamination of com (Zea mays L.) with aflatoxin, a metabolite produced by the fungus Aspergillus flavus Link: Fr., is a recurrent problem in the southeastern United States, but occasional serious outbreaks also occur in the Midwest Com Belt (21). Aflatoxins are recognized as potent hepatotoxins and carcinogens, causing mortality or reducing the productivity of farm animals (89). Aflatoxin-contaminated foodstuffs also have been associated with increased incidence of liver cancer in humans (39). In com-producing regions, the economic impact from yield loss is not very large, but A. flavus contaminates the grain with aflatoxin. Fungal toxins reduce the value of grain as an animal feed and devalue it as an export commodity (74). Any strategy that reduces the extent of aflatoxin contamination of com will result in a safer and more valuable food supply for humans and animals. Plant pathologists and com breeders have thus far been unable to identify com genotypes with substantial resistance to aflatoxin contamination. On ears in the field, A. flavus grows saprophytically on the remains of kernels damaged by insects or birds. These damaged kernels can become contaminated with substantial quantities of aflatoxin (i.e., to as much as 300,000-600,000 ppb). Aflatoxin also accumulates (to as much as 4,000 ppb) in many of the adjacent intact kernels. It does not take a large quantity of these aflatoxin-contaminated kernels to contaminate bulk grain with >20 ppb aflatoxin. At present, the only reliable method for preventing aflatoxin from entering the food chain has been the detection and segregation of aflatoxin-contaminated produce.</p