Analysis of the CRISPR-Cas system in bacteriophages active on epidemic strains of Vibrio cholerae in Bangladesh.

CRISPR-Cas (clustered regularly interspersed short palindromic repeats-CRISPR-associated proteins) are microbial nuclease systems involved in defense against phages. Bacteria also resist phages by hosting phage-inducible chromosomal islands (PICI) which prevent phage reproduction. Vibrio cholerae which causes cholera epidemics, interacts with numerous phages in the environment and in cholera patients. Although CRISPR-Cas systems are usually carried by bacteria and archea, recently V. cholerae specific ICP1 phages were found to host a CRISPR-Cas system that inactivates PICI-like elements (PLE) in V. cholerae. We analyzed a collection of phages and V. cholerae isolated during seasonal cholera epidemics in Bangladesh, to study the distribution, and recent evolution of the phage-encoded CRISPR-Cas system. Five distinct but related phages carrying the CRISPR-Cas system, and possible CRISPR-Cas negative progenitor phages were identified. Furthermore, CRISPR arrays in the phages were found to have evolved by acquisition of new spacers targeting diverse regions of PLEs carried by the V. cholerae strains, enabling the phages to efficiently grow on PLE positive strains. Our results demonstrate a continuing arms-race involving genetic determinants of phage-resistance in V. cholerae, and the phage-encoded CRISPR-Cas system in the co-evolution of V. cholerae and its phages, presumably fostered by their enhanced interactions during seasonal epidemics of cholera

In vivo sedative and hypnotic activities of methanol extract from the leaves of Jacquemontia paniculata (Burm.f.) Hallier f. in Swiss Albino mice.

BACKGROUND: The superior genus Jacquemontia belongs to Convolvulaceae, with around 120 species, and is also considered taxonomically difficult. The aim of this experiment was to assess the sedative and hypnotic activities of methanol extract from the leaves of Jacquemontia paniculata (Burm.f.) Hallier f. METHODS: The sedative and hypnotic activities were evaluated by hole-cross, open field, hole-board, elevated plus maze (EPM), and thiopental sodium-induced sleeping time determination tests in mice at doses of 200 and 400 mg/kg. RESULTS: In this investigation, we found that methanol extract of Jacquemontia paniculata (MEJP) produced a significant dose-dependent inhibition of spontaneous activity of mice both in hole-cross and open field tests. In addition, it also decreased the number of head dips in hole-board test. In the case of EPM test, this crude extract induced an anxiogenic-like effect rather than anxiolytic effect in mice. Moreover, MEJP significantly decreased the induction time to sleep and prolonged the duration of sleeping, induced by thiopental sodium. CONCLUSIONS: To conclude, these results suggest that the MEJP leaves possess potent sedative and hypnotic activities, which supported its therapeutic use for sleep disorders like insomnia