Effect of bacosides, alcoholic extract of Bacopa monniera Linn. (brahmi), on experimental amnesia in mice

To investigate the effect of bacosides (alcoholic extract of brahmi) on scopolamine (3 mg kg(-1), ip), sodium nitrite (75 mg kg(-1), ip) and BN52021 (15 mg kg(-1), ip) induced experimental amnesia in mice, using Morris water maze test, all the agents were administered 30 min before the acquisition trials on each day and repeated for 4 consecutive days, and on 5th day during the retrieval trials. Bacosides on anterograde administration (before training) in mice, significantly decreased the escape latency time (ELT) during the acquisition trials for 4 consecutive days and increased the time spent (TS) in target quadrant during the retrieval trials on 5th day, and on retrograde administration (after training) bacosides were found not to affect TS significantly. Bacosides also significantly decreased the ELT and increased the TS in mice treated anterogradely with scopolamine and sodium nitrite. Bacosides did not exhibit any significant effect on TS of mice treated retrogradely with sodium nitrite. On the other hand, bacosides significantly increased the TS of mice treated retrogradely with BN52021. On the basis of the present results it can be concluded that bacosides facilitate anterograde memory and attenuate anterograde experimental amnesia induced by scopolamine and sodium nitrite possibly by improving acetylcholine level and hypoxic conditions, respectively. Beside this bacosides also reversed BN52021 induced retrograde amnesia, probably due to increase in platelet activating factor (PAF) synthesis by enhancing cerebral glutamate level.     

Flavobacterium johnsoniae gliding motility genes identified by mariner mutagenesis

Cells of Flavobacterium johnsoniae glide rapidly over surfaces. The mechanism of F. johnsoniae gliding motility is not known. Eight gld genes required for gliding motility have been described. Disruption of any of these genes results in complete loss of gliding motility, deficiency in chitin utilization, and resistance to bacteriophages that infect wild-type cells. Two modified mariner transposons, HimarEm1 and HimarEm2, were constructed to allow the identification of additional motility genes. HimarEm1 and HimarEm2 each transposed in F. johnsoniae, and nonmotile mutants were identified and analyzed. Four novel motility genes, gldK, gldL, gldM, and gldN, were identified. GldK is similar in sequence to the lipoprotein GldJ, which is required for gliding. GldL, GldM, and GldN are not similar in sequence to proteins of known function. Cells with mutations in gldK, gldL, gldM, and gldN were defective in motility and chitin utilization and were resistant to bacteriophages that infect wild-type cells. Introduction of gldA, gldB, gldD, gldFG, gldH, gldI, and gldJ and the region spanning gldK, gldL, gldM, and gldN individually into 50 spontaneous and chemically induced nonmotile mutants restored motility to each of them, suggesting that few additional F. johnsoniae gld genes remain to be identified.     

Antibacterial Co(II), Ni(II), Cu(II) and Zn(II) complexes of Schiff bases derived from fluorobenzaldehyde and triazoles

Antibacterial Schiff bases derived from 1,2,4-triazoles as well as their metal complexes incorporating cobalt(II), nickel(II), copper(II) and zinc(II) have been synthesized and characterized. Physico-chemical studies suggest that an octahedral geometry for the cobalt(II), nickel(II) and zinc(II)and square-planer geometry for the copper(II) complexes. These complexes have been screened for antibacterial activity against three Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis and Bacillus subtilis) and two Gram-negative (Salmonella typhi and Pseudomonas aeruginosa) bacterial strains, and results compared with the activity of the free ligands. The metal complexes were found to be more potent against one or more bacterial strains than the free ligands.     

Structure of a novel phosphotyrosine-binding domain in Hakai that targets E-cadherin

Phosphotyrosine-binding domains, typified by the SH2 (Src homology 2) and PTB domains, are critical upstream components of signal transduction pathways. The E3 ubiquitin ligase Hakai targets tyrosine-phosphorylated E-cadherin via an uncharacterized domain. In this study, the crystal structure of Hakai (amino acids 106-206) revealed that it forms an atypical, zinc-coordinated homodimer by utilizing residues from the phosphotyrosine-binding domain of two Hakai monomers. Hakai dimerization allows the formation of a phosphotyrosine-binding pocket that recognizes specific phosphorylated tyrosines and flanking acidic amino acids of Src substrates, such as E-cadherin, cortactin and DOK1. NMR and mutational analysis identified the Hakai residues required for target binding within the binding pocket, now named the HYB domain. ZNF645 also possesses a HYB domain but demonstrates different target specificities. The HYB domain is structurally different from other phosphotyrosine-binding domains and is a potential drug target due to its novel structural features.