BackgroundGeothermal areas are of great interest for the study of microbial communities. The results of such investigations can be used in a variety of fields (ecology, microbiology, medicine) to answer fundamental questions, as well as those with practical benefits. Uzon caldera is located in the Uzon-Geyser depression that is situated in the centre of the Karym-Semyachin region of the East Kamchatka graben-synclinorium. The microbial communities of Zavarzin spring are well studied; however, its benthic microbial mat has not been previously described.ResultsPyrosequencing of the V3 region of the 16S rRNA gene was used to study the benthic microbial community of the Zavarzin thermal spring (Uzon Caldera, Kamchatka). The community is dominated by bacteria (>95% of all sequences), including thermophilic, chemoorganotrophic Caldiserica (33.0%) and Dictyoglomi (24.8%). The benthic community and the previously examined planktonic community of Zavarzin spring have qualitatively similar, but quantitatively different, compositions.ConclusionsIn this study, we performed a metagenomic analysis of the benthic microbial mat of Zavarzin spring. We compared this benthic community to microbial communities found in the water and of an integral probe consisting of water and bottom sediments. Various phylogenetic groups of microorganisms, including potentially new ones, represent the full-fledged trophic system of Zavarzin. A thorough geochemical study of the spring was performed.

Background: To study the changes in protein composition of atherosclerotic plaques at different stages of their development in coronary atherosclerosis using proteomics. Methods: The object of research consisted of homogenates of atherosclerotic plaques from coronary arteries at different stages of development, obtained from 15 patients. Plaque proteins were separated by two-dimensional electrophoresis. The resultant protein spots were identified by the matrix-assisted laser desorption ionization method with peptide mass mapping. Results: Groups of differentially expressed proteins, in which the amounts of proteins differed more than twofold (p < 0.05), were identified in pools of homogenates of atherosclerotic plaques at three stages of development. The amounts of the following proteins were increased in stable atherosclerotic plaques at the stage of lipidosis and fibrosis: vimentin, tropomyosin β-chain, actin, keratin, tubulin β-chain, microfibril-associated glycoprotein 4, serum amyloid P-component, and annexin 5. In plaques at the stage of fibrosis and calcification, the amounts of mimecan and fibrinogen were increased. In unstable atherosclerotic plaque of the necrotic–dystrophic type, the amounts of human serum albumin, mimecan, fibrinogen, serum amyloid P-component and annexin were increased. Conclusion: This proteomic study identifies the proteins present in atherosclerotic plaques of coronary arteries by comparing their proteomes at three different stages of plaque development during coronary atherosclerosis.

We have determined the nucleotide sequence of a flagellin gene locus from the haloalkaliphilic archaeon Natrialba magadii, identified the gene products among proteins forming flagella, and demonstrated cotranscription of the genes. Based on the sequence analysis we suggest that different regions of the genes might have distinct evolutionary histories including possible genetic exchange with bacterial flagellin genes.Representatives of the two kingdoms Archaea and Bacteria have analogous motility systems composed of long thin appendages (flagella), which rotate to produce thrust (1). The bacterial flagellum filament is mainly composed of a single type of protein. In contrast, the archaeal filament is formed from multiple types of flagellin, encoded by a few genes. Surprisingly, the archaeal flagellins (and related proteins) have homology with bacterial proteins from the type IV pilin family (4, 8) but not with bacterial flagellins (15). This fact, together with the presence of leader peptides (3, 21) and posttranslational modifications (15) in archaeal flagellins, suggests that archaeal flagella form in a manner similar to that in which bacterial pili form but not similar to that in which bacterial distal tip assembly occurs (8). The recent finding of a close relationship between the chemotaxis systems in gram-positive bacteria and archaea implies that the entire bacterial system was acquired by archaea (9). Since the chemotaxis system is involved in motility, this, in turn, raises a question about the origins and evolution of archaeal flagellin genes.We sequenced flagellin genes from poorly understood haloalkaliphilic archaeon Natrialba magadii, analyzed their expression, and demonstrated their mosaic structure. We suggest that horizontal transmissions might be involved in the evolution of the genes.Cloning, sequencing, and analysis of N. magadii flagellin genes. In the present study a 1.2-kbp DNA fragment containing Halobacterium halobium flgA1 and flgA2 genes (33) was used to search for flagellin genes in the genome of the haloalkaliphilic N. (formerly Natronobacterium) magadii. Using Southern blot hybridization (32) we identified 1.4-and 5.5-kbp fragments that gave positive signals with PstI-digested genomic DNA and 6.3-and 12.0-kbp fragments with BamHI-digested DNA. We cloned the 1.4-and 6.3-kbp fragments using plasmid-based libraries. The nucleotide sequences of the 1.4-kbp fragment and part of the 6.3-kbp fragment revealed the presence of two complete open reading frames (ORFs) and one partial ORF (Fig. 1). To sequence the distal part of the operon, we performed four rounds of inverse PCR using as templates SalI-, PstI-, HincII-, and XhoI-digested genomic DNA. The total 4,029-bp nucleotide sequence of the gene cluster contains four complete ORFs of 202, 260, 396, and 262 codons, located close to each other. In addition, we identified the 5Ј end of the ORF (127 codons), 125 nucleotides (nt) away from the cluster comprising ORF1 to ORF4 (Fig. 1). ORF1, ORF2, and ORF4 are preceded by putative ribosome binding...

No abstract