Organization of the genes necessary for hydrogenase expression in Rhodobacter capsulatus. Sequence analysis and identification of two hyp regulatory mutants

A 25kbp DNA fragment from the chromosome of Rhodobacter capsulatus B10 carrying hydrogenase (hup) determinants was completely sequenced. Coding regions corresponding to 20 open reading frames were identified. The R. capsulatus hydrogenase-specific gene (hup and hyp) products bear significant structural identity to hydrogenase gene products from Escherichia coli (13), from Rhizobium liguminosarum (16), from Azotobacter vinelandii (10) and from Alcaligenes eutrophus (11). The sequential arrangement of the R. capsulatus genes is: hupR2-hupU-hypF -hupS-hupL-hupM-hupD -hupF -hupG -hupH -huoJ -hupK -hypA-hypB-hupR1-hypC -hypD -hypE -ORF19 -ORF20 , all contiguous and transcribed from the same DNA strand. The last two potential genes do not encode products that are related to identified hydrogenase-specific gene products in other species. The sequence of the 12 R. capsulatus genes underlined above is presented. The mutation site in two of the Hup^? mutants used in this study, RS13 and RCC12, was identified in the hypF gene (deletion of one G) and in the hypD qene (deletion of 54 bp), respectively. The hypF gene product shares 45% identity with the product of hydA from E. coli and the product of hypF from R. leguminosarum. Those products present at their N-terminus a Cys arrangement typical of zinc-finger proteins. The G deletion in the C-terminal region of hypF in the RS13 mutant     

Seasonality of triplet births in the United States

Birth data on 1050 sets of triplets delivered in the United States from 1985 to 1988 were analyzed to establish whether seasonal variations in the number of triplet births occur. These data were compared to live birth data from the entire United States population over a similar period; the US data exhibit a seasonal variation with a peak in late summer. Seasonality in the number of triplet births was noted, and it differed significantly (p = 0.01) from that of the entire US population. A large peak in triplet births was seen in the spring (April-May) and a smaller peak in late summer (August-September). Only minor differences in these trends could be observed when triplet data were stratified by cause of pregnancy (spontaneous versus drug-induced ovulation) or corrected for the shorter gestations of triplet pregnancies.     

A curious occurrence of Hazenia broadyi spec. nova in Antarctica and the review of the genus Hazenia (Ulotrichales, Chlorophyceae)

Freshwater filamentous green algae with branched thalli are almost unknown from the Antarctic region. They have rarely been recorded from maritime Antarctica and from sub-Antarctic Islands with rich phanerogamic vegetation. In the genus Hazenia, only one unidentified species was reported from several subaerial sites on Signy Island in 1979. However, unique populations of this genus were recently found in the stony littoral zone of two stable shallow lakes in the northern deglaciated region of James Ross Island (NE Antarctic Peninsula). These populations have a specialized ecology; they participate in the microvegetation on the flattened surfaces of stones in the littoral zones of lakes. The dominant green filamentous and richly branched alga from these communities was transferred to monospecific culture and studied in detail. Molecular sequence data (18S ribosomal DNA and the internal transcribed spacer) indicate that it belongs to the genus Hazenia (Bold in Am J Bot 45:737–743, 1958). Based on distinct molecular, morphological, and ecological characters, this alga was described as a new species (Hazenia broadyi spec. nova). A review of the genus Hazenia, based on molecular phylogenetic analyses of available strains, was also performed.     

Discovery of novel,orally available benzimidazoles as melanin concentrating hormone receptor 1 (MCHR1) antagonists

Melanin concentrating hormone (MCH) is an important mediator of energy homeostasis and plays role in several disorders such as obesity, stress, depression and anxiety. The synthesis and biological evaluation of novel benzimidazole derivatives as MCHR1 antagonists are described. The in vivo proof of principle for weight loss with a lead compound from this series is exemplified.     

Diversity of the cyanobacterial microflora of the northern part of James Ross Island,NW Weddell Sea,Antarctica

The diversity and ecological distribution of cyanobacteria in the northern, deglaciated part of James Ross Island were studied during the Antarctic summer season 2005–2006. Seventy-five cyanobacterial morphotypes were observed in various habitats of this area. The identified cyanobacterial taxa belong to the characteristic and dominant types of coastal Antarctica, and majority of them appeared connected to special habitats and formed distinct populations and ecologically delimited communities. The results are compared and discussed with respect to phenotypically characterised cyanobacterial microflora of maritime Antarctica and to recent molecular analyses of cyanobacterial strains from different Antarctic regions. The existence of a specificity and characteristic composition of Antarctic cyanobacterial communities was demonstrated.     

Molecular phylogeny, population genetics, and evolution of heterocystous cyanobacteria using nifH gene sequences

In order to assess phylogeny, population genetics, and approximation of future course of cyanobacterial evolution based on nifH gene sequences, 41 heterocystous cyanobacterial strains collected from all over India have been used in the present study. NifH gene sequence analysis data confirm that the heterocystous cyanobacteria are monophyletic while the stigonematales show polyphyletic origin with grave intermixing. Further, analysis of nifH gene sequence data using intricate mathematical extrapolations revealed that the nucleotide diversity and recombination frequency is much greater in Nostocales than the Stigonematales. Similarly, DNA divergence studies showed significant values of divergence with greater gene conversion tracts in the unbranched (Nostocales) than the branched (Stigonematales) strains. Our data strongly support the origin of true branching cyanobacterial strains from the unbranched strains.