| 词条 | Stilbonematinae |
| 释义 |
| regnum = Animalia | phylum = Nematoda | classis = Chromadorea | classis_authority = | subclassis = Chromadoria | subclassis_authority = | ordo = Desmodorida | familia = Desmodoridae | subfamilia = Stilbonematinae | subfamilia_authority = Chitwood, 1936 | subdivision_ranks = Genera | subdivision = (See article text) }} Stilbonematinae is a subfamily of the nematode worm family Desmodoridae that is notable for its symbiosis with sulfur-oxidizing bacteria. SystematicsStilbonematinae Chitwood, 1936 belongs to the family Desmodoridae in the order Desmodorida. Nine genera have been described.[1]
DescriptionStilbonematines can be up to 10 mm long, with a club-like head. The worms are completely covered in a coat of ectosymbiotic sulfur-oxidizing bacteria except for the anterior region. The presence of the bacteria, which often contain intracellular inclusions of elemental sulfur, gives the worms a bright white appearance under incident light. They have small mouths and buccal cavities, and short pharynges. Many species have multicellular sensory-glandular organs in longitudinal rows along the length of the body, which secrete mucus that the bacterial symbionts are embedded in.[1] Stilbonematines are found in the meiofaunal habitat in marine environments.[2] Another group of meiofaunal nematodes with sulfur-oxidizing symbionts is the genus Astomonema, although in Astomonema the bacteria are endo- rather than ectosymbionts. Symbiosis with sulfur-oxidizing bacteriaThe bacterial symbionts of stilbonematines are of different shapes and sizes, ranging from small coccoid cells to elongate crescent-like cells, but each host species has only a single morphological type associated with it.[3] The bacterial symbionts of stilbonematines are closely related to the sulfur-oxidizing symbionts of gutless phallodriline oligochaete worms: these bacteria were all descended from a single ancestor, and each host species has its own specific bacterial species.[4] The bacterial symbionts are chemosynthetic, gaining energy by oxidizing sulfide from the environment, and producing biomass by fixing carbon dioxide through the Calvin-Benson-Bassham cycle.[3] The bacteria benefit from the symbiosis because the host animal can migrate between sulfide- and oxygen-rich regions of the sediment habitat, and the bacteria require both these chemical substances to produce energy. The hosts are believed to consume the bacteria as a food source, based on evidence from their stable carbon isotope ratios.[5] The specificity of the bacterial symbionts to their respective host species is controlled by a lectin called Mermaid that is produced by the worms. Mermaid occurs in different isoforms, which have differing affinities for the sugar compositions of the lipopolysaccharide coat in different bacterial species.[6] See also
References1. ^1 {{Cite journal|last=Tchesunov|first=Alexei V.|date=February 2013|title=Marine free-living nematodes of the subfamily Stilbonematinae (Nematoda, Desmodoridae): taxonomic review with descriptions of a few species from the Nha Trang Bay, Central Vietnam|url=|journal=Meiofauna Marina|volume=20|pages=71–94|via=}} {{Taxonbar|from=Q21221178}}2. ^{{Cite journal|last=Ott|first=Jörg|last2=Bright|first2=Monika|last3=Bulgheresi|first3=Silvia|date=2004|title=Symbioses between marine nematodes and sulfur-oxidizing chemoautotrophic bacteria|url=|journal=Symbiosis|volume=36|pages=103–126|via=}} 3. ^1 {{Cite journal|last=Polz|first=Martin F.|last2=Felbeck|first2=Horst|last3=Novak|first3=Rudolf|last4=Nebelsick|first4=Monika|last5=Ott|first5=Jörg A.|date=1992-11-01|title=Chemoautotrophic, sulfur-oxidizing symbiotic bacteria on marine nematodes: Morphological and biochemical characterization|journal=Microbial Ecology|language=en|volume=24|issue=3|pages=313–329|doi=10.1007/bf00167789|pmid=24193210|issn=0095-3628}} 4. ^{{Cite journal|last=Zimmermann|first=Judith|last2=Wentrup|first2=Cecilia|last3=Sadowski|first3=Miriam|last4=Blazejak|first4=Anna|last5=Gruber-Vodicka|first5=Harald R.|last6=Kleiner|first6=Manuel|last7=Ott|first7=Jörg A.|last8=Cronholm|first8=Bodil|last9=De Wit|first9=Pierre|date=2016-07-01|title=Closely coupled evolutionary history of ecto- and endosymbionts from two distantly related animal phyla|journal=Molecular Ecology|language=en|volume=25|issue=13|pages=3203–3223|doi=10.1111/mec.13554|pmid=26826340|issn=1365-294X}} 5. ^{{Cite journal|last=Ott|first=J. A.|last2=Novak|first2=R.|last3=Schiemer|first3=F.|last4=.Hentschel|first4=U|last5=Nebelsick|first5=M.|last6=Polz|first6=M.|date=1991-09-01|title=Tackling the Sulfide Gradient: A Novel Strategy Involving Marine Nematodes and Chemoautotrophic Ectosymbionts|journal=Marine Ecology|language=en|volume=12|issue=3|pages=261–279|doi=10.1111/j.1439-0485.1991.tb00258.x|issn=1439-0485}} 6. ^{{Cite journal|last=Bulgheresi|first=Silvia|last2=Gruber-Vodicka|first2=Harald R.|last3=Heindl|first3=Niels R.|last4=Dirks|first4=Ulrich|last5=Kostadinova|first5=Maria|last6=Breiteneder|first6=Heimo|last7=Ott|first7=Joerg A.|date=June 2011|title=Sequence variability of the pattern recognition receptor Mermaid mediates specificity of marine nematode symbioses|url=http://www.nature.com/ismej/journal/v5/n6/full/ismej2010198a.html?foxtrotcallback=true|journal=The ISME Journal|language=en|volume=5|issue=6|pages=986–998|doi=10.1038/ismej.2010.198|pmid=21228893|issn=1751-7362|pmc=3131856}} 2 : Chromadorea|Chemosynthetic symbiosis |
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