Balancing nutrients in a toxic environment: the challenge of eating

Insect herbivores can regulate their food intake by mixing food sources with different nutrient content, but face the resulting challenge of ingesting various plant secondary metabolites. How insects deal with toxins in a complex nutrient environment is unclear. Here we investigated the influence of a classic plant secondary metabolite, allyl glucosinolate (sinigrin), and its hydrolyzed product allyl isothiocyanate (AITC), on the development of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) when fed on diets with different protein-to-carbohydrate (p : c) ratios. We also examined the effects of these toxins on larval biochemistry, by chemically analyzing the frass produced by insects feeding on the different diets. As expected, AITC had a greater negative effect than sinigrin on H. armigera life-history traits. However, AITC at low concentration appeared to have a positive effect on some traits. Both sinigrin and AITC-induced detoxification activity in the gut, and the reaction was related to diet protein concentration. High-protein diets can provide the required free amino acid, especially cysteine, needed for the detoxification process. The nutrient content of the diet influences how plant secondary metabolites are handled, and the use of artificial diets in experiments investigating the metabolic fate of plant secondary compounds needs to be carefully evaluated.

Effect of nutritional status on arsenic and smokeless tobacco induced genotoxicity, sperm abnormality and oxidative stress in mice in vivo

BACKGROUND

Recently, high concentrations of arsenic have been documented in ground waters of Southern Assam, India. Indiscriminate smokeless tobacco consumption is a common practice in this region. Correlation between nutritional status and arsenic and smokeless tobacco-induced health effects has not been taken up in humans or other test systems.

METHODS

Mice were divided into groups based on protein (casein) content in the diet: High protein (40%), optimum protein (20%), and low protein (5%). Simultaneous chronic exposure (90 days) to arsenic and smokeless tobacco (sadagura) orally was given to evaluate the extent of the cytological and genotoxicological damage. Micronucleus assay and Comet assay of the femur bone marrow cells were conducted. Germ cell toxicity was evaluated by recording the sperm head abnormalities and total sperm count. Cell cycle analysis was performed in femur bone marrow cells using flow cytometer. Hepatic, renal, and intestinal tissues were analyzed for various oxidative stress evaluations. Histological examination of liver and kidney was performed.

RESULTS

Notably, high protein diet groups had lower arsenic and sadagura induced genotoxicity, germ cell abnormalities and oxidative stress as compared to optimum protein and low protein diet counterparts.

CONCLUSION

Our study indicates that sufficient levels of dietary protein appear to reduce the long-term arsenic and smokeless tobacco-induced toxicity in mice test system, as compared to lower or deficient amount of protein in the diet. This observation has implications and invites further studies especially epidemiological studies in the human population exposed to arsenic in South East Asian countries. Environ. Mol. Mutagen. 59:386-400, 2018. © 2018 Wiley Periodicals, Inc.