Aflatoxin contamination in groundnut induced by aspergillus flavus type fungi: A critical review.

Groundnut (Arachis hypogaea L.) is an annual legume which is also known as peanut, earthnut, monkeynut and goobers. It is the 13th most important food crop and 4th most important oilseed crop of the world. Groundnut seeds are a nutritional source of vitamin E, niacin, falacin, calcium, phosphorus, magnesium, zinc, iron, riboflavin, thiamine and potassium. Groundnut kernels are consumed directly as raw, roasted or boiled kernels or oil extracted from the kernel is used as culinary oil. It is also used as animal feed (oil pressings, seeds, green material and straw) and industrial raw material (oil cakes and fertilizer). These multiple uses of groundnut plant make it an excellent cash crop for domestic markets as well as for foreign trade in several developing and developed countries. The crop is affected by several diseases like leaf spots, collar rot, rust, bud necrosis, stem necrosis etc. Apart from these, aflatoxin is one of the major problems, produced in the infected peanut seeds by Aspergillus flavus Link ex fries and Aspergillus parasiticus Speare, particularly at the end of season under drought conditions (Diener et al., 1987). Aflatoxins are highly carcinogenic, immunosuppressive agents, highly toxic and fatal to humans and animals particularly affecting liver and digestive track. Aflatoxin is a potent human carcinogen. It is a naturally occurring toxic metabolite produced by certain fungi (Aspergillus flavus), a mold found on food products such as corn and peanuts, peanut butter. It acts as a potent liver carcinogen in rodents (and, presumably, humans). They are probably the best known and most intensively researched mycotoxins in the world. Aflatoxins have been associated with various diseases, such as aflatoxicosis, in livestock, domestic animals and humans throughout the world. In the present chapter, a detailed account on groundnut aflatoxins induced by A. flavus group of fungi was presented.

Stress responses in two genotypes of mulberry (Morus alba L.) under NaCl salinity.

Changes in biomass yield rates, cell membrane stability (CMS), malondialdehyde (MDA) content and in the levels of physiological stress markers such as proline and glycine betaine in two high yielding genotypes (S1 and ATP, salt tolerant and salt sensitive, respectively) of mulberry under NaCl salinity were studied. Biomass yield rates and CMS were significantly decreased in both the genotypes under stress conditions. Per cent of decrease in biomass yield rate and CMS was relatively less in S1 than in ATP. Salt stress results a significant increase in the accumulation of proline, by 6-fold in S1 and 4-fold in ATP. Glycine betaine content was also increased significantly in stressed plants. However, the per cent increase was more in S1 than in ATP. The level of lipid peroxidation as indicated by MDA formation was greater in ATP than in S1. These results clearly support the better salt tolerant nature of S1 compared to ATP genotype.

Response of some Calvin cycle enzymes subjected to salinity shock in vitro.

Leaf enzyme extracts of 10 day old seedlings of horsegram were subjected to NaCl or Na2SO4 treatment in vitro. Salinity shock caused decline in the activities of RuBP carboxylase, R-5-P kinase, R-5-P isomerase and NADP-Gly-3-P dehydrogenase. At low concentrations, Na2SO4 did not alter the activities of R-5-P kinase, R-5-P isomerase and NADP-Gly-3-P dehydrogenase. RuBP carboxylase was found to be more sensitive to salt shock than the other enzymes studied. Further, NaCl was more toxic to the enzyme activities as compared to Na2SO4.

Cell free ascitic fluid prevents loss of cell surface sialic acid from Zajdela Ascitic Hepatoma cells in culture.

In the Zajdela Ascitic Hepatoma (ZAH), a rat tumor, high levels of cell surface sialic acid residues are present which masked the immunogenicity of the cells. We have shown here that cell surface sialic acid level goes down rapidly when ZAH cells are put in culture. The reduction in surface sialic acid levels is due to a decrease in sialic acid residues on the major sialylated glycoprotein, gp 120, as well as a decrease in gp 120 polypeptide. The loss of sialic acid from the cultured cells is reduced if the cells are cultured in the presence of cell free ascitic fluid from ZAH tumor.

Differential amplification and expression of c-myb oncogene in Zajdela ascitic hepatoma.

Organisation and expression of c-myb protooncogene have been studied in a heterogeneous tumour the Zajdela ascitic hepatoma (ZAH). The myb gene is selectively amplified in the more tumorigenic subpopulation of the tumour while the non-lethal subpopulation does not show any change. Analysis of transcripts of the myb gene in tumorigenic versus nontumorigenic cells shows that the level of amplification of the gene does not correspond to the level of its transcription. Results have been discussed in the light of existing evidence regarding the role of c-myb gene expression during cell cycle.