SUMMARYWhole genome duplication leads to autopolyploidy and brings about an increase in cell size, concentration of secondary metabolites and enhanced cytosine methylation. The increased cell size offers a positive advantage to polyploids for cell-surface-related activities, but there is a differential response to change in body size across species and taxonomic groups. Although polyploidy has been very extensively studied, having genetic, ecological and evolutionary implications, there is no report that underscores the significance of native secondary metabolites vis-à -vis body size with ploidy change. To address this problem we targeted unique diploid-autotetraploid paired sets of eight diverse clones of six species of Cymbopogon -a species complex of aromatic grasses that accumulate qualitatively different monoterpene essential oils (secondary metabolite) in their vegetative biomass. Based on the qualitative composition of essential oils and the plant body size relationship between the diploid versus autotetraploid paired sets, we show that polyploidy brings about enhanced accumulation of secondary metabolites in all cases, but exerts differential effects on body size in various species. It is observed that the accumulation of alcohol-type metabolites (e.g. geraniol) does not inhibit increase in body size with ploidy change from 2· to 4· (r = 0.854, P < 0.01), but aldehyde-type metabolites (e.g. citral) appear to drastically impede body development (r = )0.895). Such a differential response may be correlated to the metabolic steps involved in the synthesis of essential oil components. When changed to tetraploidy, the progenitor diploids requiring longer metabolic steps in production of their secondary metabolites are stressed, and those having shorter metabolite routes better utilize their resources for growth and vigour. In situ immunodetection of 5-methylcytosine sites reveals enhanced DNA methylation in autopolyploids. It is underpinned that the qualitative composition of secondary metabolites found in the vegetative biomass of the progenitor diploid has a decisive bearing on the body size of the derived autotetraploids and brings about an enhancement in genome-wide cytosine methylation.

Lead (Pb) is one of several environmental pollutants that adversely affect human health by producing toxicity at the tissue level. The aim of the study was to understand the effects of Pb on the metabolic profiles of liver and gastrocnemius muscle of mice in relation to carbohydrate and fat metabolisms. Swiss albino mice were chosen and divided into two groups, control and Pb-treated. The Pb-treated animals were exposed to Pb at a dose of 5 mg/kg body weight for 30 days orally, which resulted in hypoglycemia, glycosuria, and increased glycogenolysis in the liver and gastrocnemius muscle of treated mice. Pyruvic acid, the end product of glycolysis decreased in muscular tissue and increased in the liver. Additionally, the activity of G-6Pase was depressed in the liver, whereas lactate dehydrogenase activity was increased in skeletal muscle only. An adaptive mechanism was initiated by stimulating glycogenolytic and retarding glycolytic activity in the liver and also by alteration of liver and muscle pyruvate dehydrogenase activity along with increased activity of malate dehydrogenase in skeletal muscle. There was enhancement of succinate dehydrogenase and nicotinamide adenine dinucleotide phosphate oxidase activities in the studied tissues. Interestingly, cholesterol, high-density lipoprotein, and low-density lipoprotein levels were elevated, whereas those of triglycerides were decreased in Pb-treated mice serum. The activities of fatty acid synthase and glyceraldehyde 3 phosphate dehydrogenase were depressed in Pb-treated mice livers. Pb also significantly altered the morphological features of the liver, skeletal muscle, and pancreas. These data suggested that subacute Pb exposure was responsible for metabolic modulation in an adaptive fashion in the liver and skeletal muscle of mice.

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Environmental stress in plants impacts many biological processes, including male gametogenesis, and affects several cytological mechanisms that are strongly interrelated. To understand the likely impact of rising temperature on reproductive fitness in the climate change regime, a study of tapetal mitosis and its accompanying meiosis over seasons was made to elucidate the influence of temperature change on the cytological events occurring during microsporogenesis. For this we used two species of an environmentally sensitive plant system, i.e., genus Cymbopogon Sprengel (Poaceae), namely Cymbopogon nardus (L.) Rendle var. confertiflorus (Steud.) Bor (2n = 20) and Cymbopogon jwaruncusha (Jones) Schult. (2n = 20). Both species flower profusely during extreme summer (48 °C) and mild winter (15 °C) but support low and high seed fertility, respectively, in the two seasons. We have shown that tapetal mitotic patterns over seasons entail differential behavior for tapetal mitosis. During the process of tapetum development there are episodes of endomitosis that form either (i) an endopolyploid genomically imbalanced uninucleate and multinucleate tapetum, and (or) (ii) an acytokinetic multinucleate genomically balanced tapetum, with the progression of meiosis in the accompanying sporogenous tissue. The relative frequency of occurrence of the two types of tapetum mitosis patterns is significantly different in the two seasons, and it is found to be correlated with the temperature conditions. Whereas, the former (genomically imbalanced tapetum) are prevalent during the hot summer, the latter (genomically balanced tapetum) are frequent under optimal conditions. Such a differential behaviour in tapetal mitosis vis-à-vis temperature change is also correspondingly accompanied by substantial disturbances or regularity in meiotic anaphase disjunction. Both species show similar patterns. The study underpins that tapetal mitotic behaviour per se could be a reasonable indicator to elucidate the effect of climate change on reproductive fitness.