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, was isolated from a bacterial mat in a Japanese hot spring. Morphologically, the isolate was an unbranched multicellular filament with a cell diameter of 08-10 µm. The bacterium was red to reddish-brown in colour and formed a distinct red bacterial mat in the natural environment. It was able to grow photoheterotrophically under anaerobic light conditions and also chemoheterotrophically under aerobic dark conditions. Optimal growth occurred at 50 SC and pH 75-80. The cells contained bacteriochlorophyll (Bchl) a and γ-carotene derivatives as photosynthetic pigments, but lacked Bchl c and chlorosomes. Cellular fatty acids in the isolate were mainly C16 :0, C14 :0 and C15 :0. The major quinone was menaquinone-11. The DNA GMC content was 620 mol % (by HPLC). Phylogenetic analysis based on 16S rDNA sequencing suggested that the isolate belonged to the anoxygenic filamentous phototrophic bacteria represented by Chloroflexus aurantiacus, but was clearly distant from all members in this group (the sequence similarities between the isolate and its relatives were less than 838 %). Based on genotypic and phenotypic data, the name Roseiflexus castenholzii gen. nov., sp. nov. is proposed for this isolate ; the type strain is HLO8 T (l DSM 13941 T l JCM 11240 T ).

Techno I og y, Tsu k u ba , lbaraki 305-8566, Japan ~~ The microbial diversity of two types of methanogenic granular sludge, mesophilic (35 "C) and thermophilic (55 "C), which had been treating sucrose/propionate/acetate-based artificial wastewater were compared. 16s rDNA clone libraries were constructed by PCR with a prokaryote-specific primer set, and partial sequencing of the clonal 165 rDNAs was conducted for phylogenetic analysis. Of 11 5 mesophilic granule and 110 thermophilic granule clones sequenced, 19 and 22 %, respectively, were phylogenetically affiliated with the domain Archaea, and the remainder in each case were assigned to the domain Bacteria. Within the domain Archaea, the 165 rDNA clones in both libraries showed relatively close relationships with those of methanogens. Within the Bacteria, a major group represented in the mesophilic clone library was the delta subclass of the Proteobacteria (27%), in which high degrees of relatedness were observed between the clonal 165 rDNA sequences and those of previously identified syntrophic bacteria and sulfate-reducing bacteria. In contrast, in the thermophilic clone library, the Thermodesulfovibrio group (19%), the green non-sulfur bacteria (18%) and the low G+C subclass of the Gram-positive bacteria (18 %) were predominant. A significant difference between the two libraries was that no clone affiliated with the Proteobacteria was detected in the thermophilic clone library, whereas the Proteobacteria was the most predominant group in the mesophilic clones. Thirty-six and 24 different sequences were found in the mesophilic and thermophilic clones, respectively, suggesting that the microbial diversity of the thermophilic granule was lower than that of the mesophilic granule.

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Siglecs are vertebrate cell-surface receptors that recognize sialylated glycans. Here we have identified and characterized a novel Siglec, named Siglec-15. Siglec-15 is a type-I transmembrane protein consisting of: (i) two immunoglobulin (Ig)-like domains, (ii) a transmembrane domain containing a lysine residue, and (iii) a short cytoplasmic tail. Siglec-15 is expressed on macrophages and/or dendritic cells of human spleen and lymph nodes. We show that the extracellular domain of Siglec-15 preferentially recognizes the Neu5Acalpha2-6GalNAcalpha- structure. Siglec-15 associates with the activating adaptor proteins DNAX activation protein (DAP)12 and DAP10 via its lysine residue in the transmembrane domain, implying that it functions as an activating signaling molecule. Siglec-15 is the second human Siglec identified to have an activating signaling potential; unlike Siglec-14, however, it does not have an inhibitory counterpart. Orthologs of Siglec-15 are present not only in mammals but also in other branches of vertebrates; in contrast, no other known Siglec expressed in the immune system has been conserved throughout vertebrate evolution. Thus, Siglec-15 probably plays a conserved, regulatory role in the immune system of vertebrates.