Background:The heterotrimeric M. tuberculosis RecBCD complex, or each of its individual subunits, remains uncharacterized. Results: MtRecD exists as a homodimer in solution, catalyzes ssDNA-dependent ATP hydrolysis, unwinding of DNA replication/recombination intermediates, and interacts with RecA. Conclusion: MtRecD possesses strong 5Ј 3 3Ј-and weak 3Ј 3 5Ј-helicase activities. Significance: These findings provide insights into the mechanism underlying DSB repair and homologous recombination in mycobacteria.

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An effective protocol for the plant regeneration via direct and indirect organogenesis has been developed from leaf explants of Asystasia gangetica (L.), cultured on Murashige and Skoog (MS) medium supplemented with various concentrations and combinations of auxin and cytokinins. Approximately 86% of explants produced direct shoots on MS medium containing 0.5 mg L −1 6-benzyladenine (BA) and 10 μg L −1 Triacontanol (TRIA) with a maximum of 4.82 ± 0.29 shoots per leaf segment. For production of callus-mediated plantlets (indirect), primarily callus was induced on MS medium containing 2 mg L −1 2,4dichlorophenoxyacetic acid (2,4-D), which was then subcultured on medium with 0.1 mg L −1 naphthaleneacetic acid (NAA), 0.5 mg L −1 BA, and 1 to 8 mg L −1 2-isopentenyl adenine (2iP) in order to develop organogenic callus and subsequent shoot induction. A maximum of 6.84 ± 0.05 shoots per callus clump was obtained on MS media supplemented with 4 mg L −1 2iP, 0.5 mg L −1 BA, and 0.1 mg L −1 NAA. The shootlets produced roots when cultured on half-strength MS media supplemented with 2 mg L −1 indole-3-butyric acid (IBA). In vitro propagated plantlets were hardened on soil rite and acclimatized to field condition with 85% survivability. The chlorophyll content of acclimatized plants was comparable with that of the mother plant, while stomatal micromorphology of regenerated plants exhibited no abnormalities. The radical scavenging and antioxidant activity of methanolic extract of leaves were measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing ability of plasma (FRAP), and phosphomolybdenum test. In all experiments, regenerated plants exhibited enhanced antioxidant potential indicating micropropagated plants could be exploited for isolation of novel biomolecules. Further, the genetic homogeneity of acclimatized plants was confirmed by PCR-based start codon targeted (SCoT) markers and ycf1b DNA barcoding primers which exhibited monomorphic bands identical to the normal mother plant and no variations were observed.

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