Inhibition of rat liver aminoacyl-tRNA synthetases in vitro after acute and chronic aflatoxin B1 administration in vivo

Rapid LA-REIMS-based metabolic fingerprinting of serum discriminates aflatoxin-exposed from non-exposed pregnant women: a prospective cohort from the Butajira Nutrition, Mental Health, and Pregnancy (BUNMAP) Study in rural Ethiopia

To date, the changes in maternal metabolic response associated with prenatal aflatoxin exposure remain largely unknown. This study investigated the effects of prenatal aflatoxin exposure on the maternal serum metabolome in rural Ethiopia. A total of 309 pregnant women were enrolled prospectively, and their serum aflatoxin concentrations were measured using targeted liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Serum metabolic fingerprints were obtained using laser-assisted rapid evaporative ionization mass spectrometry (LA-REIMS), followed by combination of univariate and multivariate statistical modelling to evaluate changes in circulating metabolic features between aflatoxin-exposed and unexposed mothers and to select discriminatory metabolic features. The analysis revealed that 81.8% of women were exposed to aflatoxins, with a median concentration of 12.9 pg/mg albumin. The orthogonal partial least square discriminant analysis (OPLS-DA) regression model demonstrated significant disparities in the serum metabolome when comparing Ethiopian pregnant women with low vs high aflatoxin exposure. Thirty-two differentially expressed metabolic features were identified, affecting aminoacyl-tRNA biosynthesis pathway. Several discriminatory metabolites have been identified, including glutamine, tryptophan, tyrosine, carnosine, and 1-methylnicotinamide. In conclusion, our findings indicate that aflatoxin exposure during pregnancy have shown disparities in the maternal serum metabolome, primarily affecting protein synthesis. Further research is needed to identify specific metabolite biomarkers and elucidate the underlying mechanisms.

Higher eukaryotic aminoacyl-tRNA synthetases in physiologic and pathologic states

The aminoacyl-tRNA synthetases play a dual role in cell metabolism by synthesizing aminoacyl-tRNAs and an odd dinucleotide diadenosine-5', 5''-P1, P4-tetraphosphate which appears to be involved in DNA replication and the control of cell proliferation. This review is a synthesis of recent results on the structure, genetics, cell biology, physiology, role in neoplasia, and role in autoimmune myositis of the higher eukaryotic aminoacyl-tRNA synthetases.

Lack of effect of long-term glutathione administration on aflatoxin B1-induced hepatoma in male rats

The effect of long-term GSH administration on aflatoxin B1 (AFB1)-induced carcinogenesis in the livers of male Wistar II rats was evaluated. No significant effect of an 11 months period of reduced glutathione (GSH) administration was observed concerning both the survival curve and the incidence of liver tumors. Liver tissues of all animals were bearing tumors or nodular lesions 24 months after AFB1 treatment, regardless of GSH treatment. The capacity of the GSH conjugation system was elevated in the liver tissue of AFB1-treated animals both by an increase of GSH content and an increase of the specific activities of several GSH S-transferase isoenzymes. Likewise the specific activities of GSH related enzymes as GSSG reductase and gamma-glutamyltransferase (gamma-GT) and the activity of the GSH independent detoxication system NAD(P)H:quinone oxidoreductase were increased in the AFB1-treated livers, there was no significant effect of GSH treatment. These results demonstrate that long-term GSH treatment has no effect on the survival of AFB1-pretreated male rats on the incidence of liver tumors and on the activities of drug metabolizing systems. The hepatic detoxication capacity 24 months after AFB1 treatment is elevated.

Zinc supplementation in ethanol-treated pregnant rats increases the metabolic activity in the fetal hippocampus

As a possible preventative measure for brain dysfunction in the fetal alcohol syndrome, the effect of zinc supplementation together with ethanol on the fetal cerebrum, especially the hippocampus, was investigated. Female rats of an ethanol group and a control group received 30% ethanol and water, respectively. During pregnancy half of both groups received 0.01% zinc together with ethanol or water. Fetuses on gestational day 21 were examined biochemically and ultrastructurally. Administration of zinc with ethanol resulted in an increased cerebral weight and cerebral RNA content compared to administration of ethanol alone. However, these better results did not reach those of controls without ethanol. In the cytoplasm of hippocampal neurons from dams only given zinc with ethanol confronting cisternae were frequently observed between the rough endoplasmic reticulum and the rough endoplasmic reticulum or the nuclear envelope. Although the functional roles of the confronting cisternae were not definite, it is reasonable to conclude that the confronting cisternae were a repair mechanism of zinc against the inhibitory effect on RNA and protein syntheses of ethanol. This study shows evidence of prevention of the brain dysfunction on ethanol treatment.

Synthesis of transfer RNA in rat liver after acute and chronic aflatoxin B1 administration

Synthesis of rat liver tRNA following acute and chronic administration of aflatoxin B1 was compared to protein synthesis. Twenty hours after acute administration of aflatoxin B1 total RNA synthesis was inhibited by 91% and tRNA synthesis by 77% while protein synthesis as assayed in vitro was inhibited by 75%. In the chronic (long-term) experiment at 7, 18 and 30 weeks after administration of aflatoxin B1 no inhibition of total RNA and tRNA synthesis was observed but protein synthesis in the cell-free system was inhibited by 16%. Thus, the inhibitory effects on protein synthesis observed in the long-term experiments are not correlated with the inhibition of tRNA synthesis.