Preoviposition Activation of Cathepsin-like Proteinases in Degenerating Ovarian Follicles of the Mosquito Culex pipiens pallens

Developmental Biology

Yuki Eshita¹  Eiki Kominami¹  Daijiro Ohmori¹  Akihiro Fukunaga¹  Takashi Ueno¹  Masako Nishizuka¹  Keikichi Uchida¹ 

[1] Department of Biology, Juntendo University School of Medicine, 1-1 Hiraga Gakuerdai, Inba-gun, Chiba, 270-1695, Japan

关键词: ovary;    oocyte;    follicle;    oogenesis;    follicular atresia;    oosorption;    degeneration;    egg proteinase;    cathepsins;    mosquito;   

DOI  :  10.1006/dbio.2001.0357

学科分类：生物科学（综合）

来源: Academic Press

【 摘 要 】

Withindevelopingovariesofmanyinsects,somedevelopingfolliclesoroocytesusuallydegenerate(follicularatresiaoroosorption),whiletheothersmaycontinuetogrowtomaturity,thusmaintainingthebalancebetweenthenumberofeggsandreproductivecircumstancessuchasavailablenutrients.Tohelpclarifythephenomenonoffollicularatresiaduringovariandevelopment,weexaminedcysteineproteinasesstoredinmosquitoCulexpipienspallensovaries.First,analysisusingsynthesizedsubstratesshowedthatcathepsinB-andL-likeproteinasesgraduallyaccumulatedinthedevelopingovariesafterabloodmeal,whichrequiredmorethan10minofpreincubationunderacidicconditionstoreachtheirmaximumactivities.However,homogenatesofdegeneratingfollicles3daysafterfeedingshowedproteolyticactivitieswithoutacidtreatment,suggestingthattheproteinaseshadalreadybeenactivated,whiletheextractofnormallydevelopingfolliclescollectedfromthesameovariesrequiredmorethan10minofacidpreincubationtoreachtheoptimumactivities,suggestingthattheenzymesremainedasinactiveforms.Chemicalandimmunohistochemicalanalysesshowedthatmoreproteinasesarelocatedinthecytoplasm,ratherthanbeingassociatedwithyolkgranules.Ovarianproteinases,whicharebelievedtobecomeactivatedattheonsetofembryogenesis,shouldalsobeactivatedduringoogenesis,presumablytoenhanceoosorption.

【 授权许可】

Unknown