Riftia pachyptila: Diferenzas entre revisións
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Liña 28:
Teñen unha "pluma" vermella moi vasclarizada no extremo do seu extremo libre, que é un órgano para o intercambio de compostos co ambiente (por exemplo, [[sulfuro de hidróxeno|H<sub>2</sub>S]], [[dióxido de carbono|CO<sub>2</sub>]], [[oxíxeno|O<sub>2</sub>]], etc.). Os vermes tubulares non teñen moitos predadores. Se son ameazados, a pluma pode retraerse dentro do tubo protector do verme. A pluma proporciona nutrientes esenciais ás [[bacteria]]s que viven dentro do [[trofosoma]]. Estes vermes tubícolas non teñen tracto dixestivo de adultos, pero as bacterias (que poden supoñer ata a metade do peso corporal do verme) converten o [[oxíxeno]], [[sulfuro de hidróxeno]], [[dióxido de carbono]], etc. en moléculas orgánicas das cales se alimentan os vermes hóspedes. Este proceso,coñecido como [[quimiosíntese]], foi recoñecido no trofosoma por [[Colleen Cavanaugh]].<ref name="Cavanaugh1981">{{cite journal | last = Cavanaugh | first = Colleen M. | authorlink = | title = Prokaryotic Cells in the Hydrothermal Vent Tube Worm ''Riftia pachyptila'' Jones: Possible Chemoautotrophic Symbionts | journal = Science | volume = 213 | issue = 4505 | pages = 340–342 | year = 1981 | doi = 10.1126/science.213.4505.340 | pmid = 17819907 | display-authors = 1 | last2 = Gardiner | first2 = S. L. | last3 = Jones | first3 = M. L. | last4 = Jannasch | first4 = H. W. | last5 = Waterbury | first5 = J. B. }}</ref>
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The bright red color of the plume structures results from several extraordinarily complex [[hemoglobin]]s, which contain up to 144 [[globin chain]]s (each presumably including associated heme structures). These tube worm hemoglobins are remarkable for carrying oxygen in the presence of sulfide, without being inhibited by this molecule as hemoglobins in most other species are.<ref>{{cite journal |vauthors=Zal F, Lallier FH, Green BN, Vinogradov SN, Toulmond A |title=The multi-hemoglobin system of the hydrothermal vent tube worm ''Riftia pachyptila''. II. Complete polypeptide chain composition investigated by maximum entropy analysis of mass spectra |journal=J. Biol. Chem. |volume=271 |issue=15 |pages=8875–81 |date=Apr 1996 |pmid=8621529 |doi= 10.1074/jbc.271.15.8875 |issn=0021-9258 |url=http://www.jbc.org/cgi/pmidlookup?view=long&pmid=8621529 |format=Free full text}}</ref><ref>{{cite journal |vauthors=Minic Z, Hervé G |title=Biochemical and enzymological aspects of the symbiosis between the deep-sea tubeworm ''Riftia pachyptila'' and its bacterial endosymbiont |journal=Eur. J. Biochem. |volume=271 |issue=15 |pages=3093–102 |date=Aug 2004 |pmid=15265029 |issn=0014-2956 |format=Free full text | doi=10.1111/j.1432-1033.2004.04248.x}}</ref>▼
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Nitrate and nitrite are toxic, but nitrogen is required for biosynthetic processes. The chemosynthetic bacteria within the trophosome convert this nitrate to [[ammonium]] ions, which then are available for production of amino acids in the bacteria, which are in turn released to the tube worm. To transport nitrate to the bacteria, ''R. pachyptila'' concentrate nitrate in their blood, to a concentration 100 times more concentrated than the surrounding water. The exact mechanism of ''R. pachyptila''’s ability to withstand and concentrate nitrate is still unknown.<ref>{{cite journal|author1=Edda Hahlbeck |author2=Mark A. Pospesel |author3=Franck Zal |author4=James Childress |author5=Horst Felbeck |title=Proposed nitrate binding by hemoglobin in ''Riftia pachyptila'' |journal=Deep-Sea Research |volume=52 |issue=10 |pages=1885–1895 |date=July 2005 |pmid= |doi=10.1016/j.dsr.2004.12.011 |issn=0967-0637 |url=http://sbr.sb-roscoff.fr/Ecophy/PDF/05-Hahlbeck-DSR.pdf |format=Free full text }}{{dead link|date=January 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>
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