KEY MESSAGE : The regulation of GS isoforms by WD was organ specific. Two GS isoforms i.e. OsGS1;1 and OsGS2 were differentially regulated in IR-64 (drought-sensitive) and Khitish (drought-tolerant) cultivars of rice. Water deficit (WD) has adverse effect on rice (Oryza sativa L.) and acclimation requires essential reactions of primary metabolism to continue. Rice plants utilize ammonium as major nitrogen source, which is assimilated into glutamine by the reaction of Glutamine synthetase (GS, EC 6.3.1.2). Rice plants possess one gene (OsGS2) for chloroplastic GS2 and three genes (OsGS1;1, OsGS1;2 and OsGS1;3) for cytosolic GS1. Here, we report the effect of WD on regulation of GS isoforms in drought-sensitive (cv. IR-64) and drought-tolerant (cv. Khitish) rice cultivars. Under WD, total GS activity in root and leaf decreased significantly in IR-64 seedlings in comparison to Khitish seedlings. The reduced GS activity in IR-64 leaf was mainly due to decrease in GS2 activity, which correlated with decrease in corresponding transcript and polypeptide contents. GS1 transcript and polypeptide accumulated in leaf during WD, however, GS1 activity was maintained at a constant level. Total GS activity in stem of both the varieties was insensitive to WD. Among GS1 genes, OsGS1;1 expression was differently regulated by WD in the two rice varieties. Its transcript accumulated more abundantly in IR-64 leaf than in Khitish leaf. Following WD, OsGS1;1 mRNA level in stem and root tissues declined in IR-64 and enhanced in Khitish. A steady OsGS1;2 expression patterns were noted in leaf, stem and root of both the cultivars. Results suggest that OsGS2 and OsGS1;1 expression may contribute to drought tolerance of Khitish cultivar under WD conditions.

No abstract

Rice (Oryza sativa L.) straw, an agricultural waste of high yield, is a sustainable source of fermentable sugars for biofuel and other chemicals. However, it shows recalcitrance to microbial catalysed depolymerization. We herein describe development of thermotolerant microbial consortium (RSV) from vermicompost with ability to degrade rice straw and analysis of its metagenome for bacterial diversity, and lignocellulolytic carbohydrate active enzymes (CAZymes) and their phylogenetic affiliations. RSV secretome exhibited cellulases and hemicellulases with higher activity at 60 °C. It catalysed depolymerization of chemical pretreated rice straw as revealed by scanning electron microscopy and saccharification yield of 460 mg g−1 rice straw. Microbial diversity of RSV was distinct from other compost habitats, with predominance of members of phyla Firmicutes, Proteobacteria and Bacteroidetes; and Pseudoclostridium, Thermoanaerobacterium, Chelatococcus and Algoriphagus being most abundant genera. RSV harboured 1389 CAZyme encoding ORFs of glycoside hydrolase, carbohydrate esterase, glycosyl transferase, carbohydrate binding module and auxiliary activity functions. Microorganisms of Firmicutes showed central role in lignocellulose deconstruction with importance in hemicellulose degradation; whereas representatives of Proteobacteria and Bacteroidetes contributed to cellulose and lignin degradation, respectively. RSV consortium could be a resource for mining thermotolerant cellulolytic bacteria or enzymes and studying their synergism in deconstruction of chemically pretreated rice straw.

No abstract

No abstract

Vanadium is an important regulator of cellular growth, differentiation, and cell death, and thus has received increasing attention to be an effective cancer chemopreventive agent. In the present study, attempts have been made to investigate the in vivo antineoplastic effect of this micronutrient at the 0.5 ppm dosage in drinking water, by monitoring hepatic nodulogenesis and hepatocellular phenotype followed by antioxidant status and atomic absorption spectrometric estimation of some essential biometals during the multistage of carcinogenesis induced by 2-acetylaminofluorene (2-AAF; 0.05% in basal diet). Finally, sister-chromatid exchange (SCE) and DNA-protein crosslink (DPC) formation, as potential biomarkers were estimated to find out the suppressive effect of vanadium at the molecular level. The results showed that vanadium administration throughout the experiment reduced the relative liver weight, nodular incidence (48.40%), total number, and multiplicity (63.91%), and altered the size of visible persistent nodules (PNs) with concurrent restoration of hepatic glutathione (P < 0.01), glutathione-S-transferase (P < 0.001) and manganese-dependent superoxide dismutase (P < 0.001) activities as well as, hepatic zinc and copper contents (P < 0.001) when compared to the carcinogen control. Moreover, vanadium treatment significantly reduced SCE frequency (50.24%) and DPC coefficient (P < 0.001; 21.30%). Our results, thus, strongly suggest that supplementary vanadium at a dose of 0.5 ppm, when administered continuously throughout the study, than administered either in the initiation or promotion phase alone, is very much effective in suppressing neoplastic transformation during 2-AAF-induced in vivo rat hepatocarcinogenesis.

No abstract

No abstract