Descripción: EGS (external guide sequence) technology is a promising approach to designing new antibiotics. EGSs are short antisense oligoribonucleotides that induce RNase P-mediated cleavage of a target RNA by forming a precursor tRNA-like complex. The ftsZ mRNA secondary structure was modeled and EGSs complementary to two regions with high probability of being suitable targets were designed. In vitro reactions showed that EGSs targeting these regions bound ftsZ mRNA and elicited RNase P-mediated cleavage of ftsZ mRNA. A recombinant plasmid, pEGSb1, coding for an EGS that targets region "b" under the control of the T7 promoter was generated. Upon introduction of this plasmid into Escherichia coli BL21(DE3)(pLysS) the transformant strain formed filaments when expression of the EGS was induced. Concomitantly, E. coli harboring pEGSb1 showed a modest but significant inhibition of growth when synthesis of the EGSb1 was induced. Our results indicate that EGS technology could be a viable strategy to generate new antimicrobials targeting ftsZ. © 2012 Sala et al.

Descripción: Using quantitative real-time PCR, the expression of mRNAs encoding three transport-related proteins and one putative housekeeping protein was analyzed in anterior and posterior gills of the euryhaline crab Chasmagnathus granulatus following transfer from isosmotic conditions (30‰ salinity) to either dilute (2‰) or concentrated (45‰) seawater. Modest changes were observed in the abundance of mRNAs encoding the housekeeping protein arginine kinase and the vacuolar-type H+-ATPase B-subunit, both of which were highly expressed under all conditions. By contrast, the expression of Na +/K+-ATPase α-subunit mRNA and Na+/K +/2Cl- cotransporter mRNA was strongly responsive to external salinity. During acclimation to dilute seawater, cotransporter mRNA increased 10-20-fold in posterior gills within the first 24 h while Na +/K+-ATPase α-subunit mRNA increased 35-55-fold. During acclimation to concentrated seawater, cotransporter mRNA increased 60-fold by 96 h and Na+/K+-ATPase α-subunit increased approximately 25-fold in posterior gills. Our results indicate a complex pattern of transcriptional regulation dependent upon the direction of salinity change and the developmental background of the gills.

Descripción: In order to assess the relationship between the genus Kluyvera and other members of the family Enterobacteriaceae, the 16S rRNA genes of type strains of the recognized Kluyvera species, Kluyvera georgiana, Kluyvera cochleae, Kluyvera ascorbata and Kluyvera cryocrescens, were sequenced. A comparative phylogenetic analysis based on these 16S rRNA gene sequences and those available for strains belonging to several genera of the family Enterobacteriaceae showed that members of the genus Kluyvera form a cluster that contains all the known Kluyvera species. However, the type strain of Enterobacter intermedius (ATCC 33110 T ) was included within this cluster in a very close relationship with the type strain of K. cochleae (ATCC 51609 T ). In addition to the phylogenetic evidence, biochemical and DNA-DNA hybridization analyses of species within this cluster indicated that the type strain of E. intermedius is in fact a member of the genus Kluyvera and, within it, of the species Kluyvera cochleae. Therefore, following the current rules for bacterial nomenclature and classification, the transfer of E. intermedius to the genus Kluyvera as Kluyvera intermedia comb. nov. is proposed (type strain, ATCC 33110 T =CIP 79.27 T =LMG 2785 T =CCUG 14183 T ). Biochemical analysis of four E. intermedius strains and one K. cochleae strain independent of the respective type strains further indicated that E. intermedius and K. cochleae represent the same species and are therefore heterotypic synonyms. Nomenclatural priority goes to the oldest legitimate epithet. Consequently, Kluyvera cochleae Müller et al. 1996 is a later synonym of Kluyvera intermedia (Izard et al. 1980) Pavan et al. 2005. © 2005 IUMS.