title: Molecular evidence of digestion and absorption of epibiotic bacterial community by deep-sea crab Shinkaia crosnieri.
abstract: The hydrothermal vent crab Shinkaia crosnieri is considered to obtain nutrition from the epibiotic bacteria found on the setae, but previous studies have not shown how nutrients can be transferred from the epibionts to the host. In this study, microscopic observations of S. crosnieri intestinal components detected autofluorescent setae fragments and pigmentation derived from the digestion of epibionts in a dye-stained epibiont tracer experiment. An in vitro digestion experiment with epibiotic populations using an intestinal extract demonstrated the degradation of epibiotic cells by digestive enzymes. A phylogenetic analysis showed that many of the bacterial 16S ribosomal RNA gene sequences obtained from the intestine were closely related to the sequences of the epibionts, thus they were probably derived from the epibionts. A stable isotope tracer experiment also indicated that (13)C assimilated by the epibionts provided a carbon (nutrition) source for the host. Both activity measurements and isotope studies showed that chemosynthetic metabolism by the gut microbial components were inactive. Together with the feeding behaviour of living S. crosnieri, these results indicate that S. crosnieri ingests the epibionts using maxillipeds and assimilates them via its digestive organs as a nutrient source. The results of this study elucidate the mechanism of nutritional transfer in ectosymbiosis between chemosynthetic bacteria and deep-sea invertebrates.
authors.affiliation: Department of Subsurface Geobiological Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Kanagawa, Japan.
authors.forename: Tomo-O
authors.initials: TO
authors.lastname: Watsuji
authors.affiliation: 1] Department of Subsurface Geobiological Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Kanagawa, Japan [2] Life Science Research Center, College of Bioresource Sciences, Nihon University, Fujisawa, Japan.
authors.forename: Asami
authors.initials: A
authors.lastname: Yamamoto
authors.affiliation: 1] Department of Subsurface Geobiological Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Kanagawa, Japan [2] Life Science Research Center, College of Bioresource Sciences, Nihon University, Fujisawa, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Motoki
authors.affiliation: Life Science Research Center, College of Bioresource Sciences, Nihon University, Fujisawa, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Ueda
authors.affiliation: Department of Subsurface Geobiological Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Kanagawa, Japan.
authors.forename: Emi
authors.initials: E
authors.lastname: Hada
authors.affiliation: Department of Subsurface Geobiological Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Kanagawa, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Takaki
authors.affiliation: Department of Subsurface Geobiological Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Kanagawa, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Kawagucci
authors.affiliation: Department of Subsurface Geobiological Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Kanagawa, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Takai
mesh_terms: D000818:Animals; D033381:Anomura / Q000382:microbiology* / Q000502:physiology*; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D044822:Biodiversity; D004063:Digestion; D041981:Gastrointestinal Tract / Q000382:microbiology / Q000502:physiology; D060086:Hydrothermal Vents / Q000382:microbiology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology*
chemical_list: D012336:RNA, Ribosomal, 16S