Alvinella pompejana is a polychaetous annelid that inhabits active deep-sea hydrothermal vent sites along the East Pacific Rise, where it colonizes the walls of actively venting high-temperature chimneys. An abundant, morphologically diverse epibiotic microflora is associated with the worm's dorsal integument, with a highly integrated filamentous morphotype clearly dominating the microbial biomass. It has been suggested that this bacterial population participates in either the nutrition of the worm or in detoxification of the worm's immediate environment. The primary goal of this study was to phylogenetically characterize selected epibionts through the analysis of 16S rRNA gene sequences. Nucleic acids were extracted from bacteria collected from the dorsal surface of A. pompejana. 16S rRNA genes were amplified with universal bacterial primers by the PCR. These genes were subsequently cloned, and the resulting clone library was screened by restriction fragment length polymorphism analysis to identify distinct clone types. The restriction fragment length polymorphism analysis identified 32 different clone families in the library. Four of these families were clearly dominant, representing more than 65% of the library. Representatives from the four most abundant clone families were chosen for complete 16S rRNA gene sequencing and phylogenetic analysis. These gene sequences were analyzed by a variety of phylogenetic inference methods and found to be related to the newly established epsilon subdivision of the division Proteobacteria. Secondary structural model comparisons and comparisons of established signature base positions in the 16S rRNA confirmed the placement of the Alvinella clones in the epsilon subdivision of the Proteobacteria.

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Summary. The human C3R receptor, which binds C3bi, present on the surface of monocytes, granulocytes and natural killer cells, can be detected by several monoclonal antibodies, OKMI, Mol and Mac-1 and also by RM2.I84 which detects a polymorphism of the receptor. Platelets have been considered to lack complement receptors on their cell surface; however, we now describe the detection of CR3 receptors on human platelets by radioimmunoassay using both OKMI and RM2.184 antibodies. Using OKMI, immunoprecipitation studies with '"I-labelled platelets revealed the typical CR3 complex with an a chain of 165,000 daltons and (3 chain of 95,000 daltons. By immunofluorescence, megakaryocytes were also found to be OKMI ^. However, platelet CR3 does not merely bind C3bi, but the binding of the OKMI antibody to platelet CR3 selectively blocks platelet functions of aggregation and serotonin release induced by arachadonic acid but not by other ligands (ristocetin, ADP, L-epinephrine, collagen and thrombin). The studies demonstrate an important role of platelet CR3 in both complement binding and in prostaglandin metabolic pathways.