On sexual agglutination and mating type substances in isogamous dioecious Chlamydomonads: IV. Unilateral inactivation of the sex contact capacity in compatible and incompatible taxa by α-mannosidase and snake venom protease☆

[摘要] SexcellcontactatfertilizationisanalysedinthematingtypereactionofisogamousChlamydomonasspecies.Contactisbaseduponacomplementaritybetweenspecialmatingtypesubstances,sexandspeciesspecificglycoproteincomplexes.Inthreerelatedtaxa,thecontactcapactiyoftheir(+)gametetypeissensitivetosnakevenomprotease(α-protease)anddependsdecisivelyonterminalα-glycosidicallyboundmannoseresidues.Enzymaticremovaloftheseresiduesbyα-mannosidaseincapacitateslive(+)gametesandinactivatesisolated(+)matingtypesubstance.(+)gametesinactivatedbyα-mannosidaseorα-proteasedonotagglutinatewith(−)gametesnorrespondtoisolated(−)matingtypesubstance.Isolated(−)substanceisadsorbedtoandinactivatedbythehomologous(+)gametes.(+)gametesincapacitatedbyα-mannosidaseorα-proteasedonotadsorbnorinactivatetheisolated(−)substance.Theagglutinabilityoflive(−)gametesandthecontactcapacityofisolated(−)matingtypesubstanceisnotaffectedbyα-mannosidaseorα-protease.Themannoseresiduesreactonlywithinthespecies-typicalcomplementarity.Someadditionalfeature(s)ofthe(+)matingtypesubstancesmusteffecttheirspeciesspecificityandaccountforgameticisolationandsexualincompatibilitybetweenspecies.

[学科分类] 生物科学（综合）