Effect of aflatoxin B1 on chromatin-bound ribonucleic acid polymerase and nucleic acid and protein synthesis in germinating maize seeds

Abstract

The treatment of germinating maize seeds (cv. Ganga 2) with aflatoxin B1 resulted in suppression of ribonucleic acid (RNA), protein, and deoxyribonucleic acid (DNA) synthesis at 3, 4, and 5 h, respectively. At or below the concentrations inhibitory for these in vivo syntheses, the toxin inhibited chromatin-bound DNAdependent RNA polymerase activity. The synthesis of both polyadenylated and non-polyadenylated RNA was inhibited, but the effect on the former was more pronounced. Equilibrium dialysis and difference spectral and viscometric analyses showed a binding of aflatoxin B1 to DNA isolated from the seeds. It is proposed that the inhibition of RNA synthesis in maize seeds by the toxin is due to the interference with the RNA polymerase activity, which seems, at least partially, due to the impairment of DNA template functions. Aflatoxins, the secondary metabolites of Aspergillus flavus and A. parasiticus, are one of the most potent chemical hepatocarcinogens known (12). Of the several aflatoxins produced by these fungi, aflatoxin B1 (AB,) is the most abundant and shows the highest toxicity. Besides affecting animal systems, which have been a subject of intense research, aflatoxins also affect plant systems (24). Some of the effects reported on plants include inhibition of seed germination, synthesis of a-amylase and lipase,

The protective role of zinc and calcium in Vicia faba seedlings subjected to cadmium stress

“…Thus, Ca 2þ ions reduce the toxic effect of Cd 2þ on broad bean seedling. Other investigators have noted the similar protective effect of Ca 2þ against toxic effects of Cd 2þ (Agar and Taspinar, 2003;Busby and Wogan, 1985;Neal, 1987;Tripathi and Misra, 1981).…”

Mycotoxins Affecting Animals, Foods, Humans, and Plants: Types, Occurrence, Toxicities, Action Mechanisms, Prevention, and Detoxification Strategies—A Revisit

“…In mice fed for 4 weeks using maize contaminated with mycotoxin (ZEA, aflatoxin, and DON), the oocyte histone methylation and DNA methylation changed [203]. (h) RNA polymerase effects: AFB1 has inhibitory effects on chromatin-bound RNA polymerase, which is DNA-dependent, and consequently interferes with synthesis of RNA [204,205]. Luteoskyrin and patulin also inhibit RNA polymerase [204,205].…”

“…(h) RNA polymerase effects: AFB1 has inhibitory effects on chromatin-bound RNA polymerase, which is DNA-dependent, and consequently interferes with synthesis of RNA [204,205]. Luteoskyrin and patulin also inhibit RNA polymerase [204,205]. (i) Necrosis and apoptosis: AFB1 cytotoxic effects in lymphocytes of humans involve necrosis, caspase activation, and apoptosis [206], which lead to programmed cell death and irreversible cell damage.…”

Determination of protective role of selenium against aflatoxin B1-induced DNA damage

“…As result of the GTS value, transcription and translation are affected. Previous studies found that AFB 1 affects GTS, polymorphism value, transcription and translation by binding to DNA in plant and animal organisms (Essigmann et al, 1982; Tripathi and Misra, 1981). This effect of AFB 1 on cells decreased after treatment with different concentration of Se 4+ + AFB 1 .…”

“…Previous articles about the effect of AFB 1 on higher plants indicated that it affects amino acid uptake, chlorophyll synthesis, germination of seeds, elongation of some plant roots and stems, protein synthesis, total carbohydrate and lipid content, RNA synthesis, chromosomal aberrations and the fidelity of DNA (Jones et al, 1980; Tripathi and Misra, 1981). Recently, several factors present in the foods of common consumption have been shown to modify these critical reactions of AFB 1 in animal (Bhattacharya et al, 1984).…”