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dc.contributor.authorRaldúa, Demetrio-
dc.contributor.authorFabra, Mercedes-
dc.contributor.authorBozzo, María G.-
dc.contributor.authorWeber, Ekkehard-
dc.contributor.authorCerdà, Joan-
dc.date.accessioned2010-02-04T16:06:00Z-
dc.date.available2010-02-04T16:06:00Z-
dc.date.issued2006-
dc.identifier.citationAJP - Regulatory, Integrative and Comparative Physiology 290(2): R456-R466 (2006)en_US
dc.identifier.issn0363-6119-
dc.identifier.urihttp://hdl.handle.net/10261/20712-
dc.description12 pages, 9 figures, 1 tableen_US
dc.description.abstractIn teleost oocytes, yolk proteins (YPs) derived from the yolk precursors vitellogenins are partially cleaved into free amino acids and small peptides during meiotic maturation before ovulation. This process increases the osmotic pressure of the oocyte that drives its hydration, which is essential for the production of buoyant eggs by marine teleosts (pelagophil species). However, this mechanism also occurs in marine species that produce benthic eggs (benthophil), such as the killifish (Fundulus heteroclitus), in which oocyte hydration is driven by K+. Both in pelagophil and benthophil teleosts, the enzymatic machinery underlying the maturation-associated proteolysis of YPs is poorly understood. In this study, lysosomal cysteine proteinases potentially involved in YP processing, cathepsins L, B, and F (CatL, CatB, and CatF, respectively), were immunolocalized in acidic yolk globules of vitellogenic oocytes from the killifish. During oocyte maturation in vitro induced with the maturation-inducing steroid (MIS), CatF disappeared from yolk organelles and CatL became inactivated, whereas CatB proenzyme was processed into active enzyme. Consequently, CatB enzyme activity and hydrolysis of major YPs were enhanced. Follicle-enclosed oocytes incubated with the MIS in the presence of bafilomycin A1, a specific inhibitor of vacuolar-type H+ ATPase, underwent maturation in vitro, but acidification of yolk globules, activation of CatB, and proteolysis of YPs were prevented. In addition, MIS plus bafilomycin A1-treated oocytes accumulated less K+ than those stimulated with MIS alone; hence, oocyte hydration was reduced. These results suggest that CatB is the major protease involved in yolk processing during the maturation of killifish oocytes, whose activation requires acidic conditions maintained by a vacuolar-type H+-ATPase. Also, the data indicate a link between ion translocation and YP proteolysis, suggesting that both events may be equally important physiological mechanisms for oocyte hydration in benthophil teleosts.en_US
dc.description.sponsorshipThis work was supported by the Spanish Ministry of Science and Technology Grant AGL2001-0364 and by a grant from the Reference Center in Aquaculture, Generalitat de Catalunya, Spainen_US
dc.format.extent22195 bytes-
dc.format.mimetypeapplication/pdf-
dc.language.isoengen_US
dc.publisherAmerican Physiological Societyen_US
dc.rightsclosedAccessen_US
dc.subjectFundulus heteroclitusen_US
dc.subjectOocyte maturationen_US
dc.subjectHydrationen_US
dc.subjectVacuolar-typeen_US
dc.subjectH+-ATPaseen_US
dc.subjectCathepsinen_US
dc.titleCathepsin B-mediated yolk protein degradation during killifish oocyte maturation is blocked by an H+-ATPase inhibitor: effects on the hydration mechanismen_US
dc.typeartículoen_US
dc.identifier.doi10.1152/ajpregu.00528.2005-
dc.description.peerreviewedPeer revieweden_US
dc.relation.publisherversionhttp://dx.doi.org/10.1152/ajpregu.00528.2005en_US
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