Programmed autophagocytosis accompanying conjugation in the ciliate Stylonychia mytilus☆

[摘要] ConjugationandpostconjugantdevelopmentinStylonychiaisaccompaniedbyaperiodofapproximately80hrduringwhichthecellsareunabletoingestfood.Thisperiodisoneofconsiderablesyntheticactivity,encompassingimportantportionsofthedevelopmentofthenewmacronucleus.Light-andelectron-microscopicobservationsofconjugatingpairsandexconjugantcellsrevealaprocessofautophagocytosisthatmayprovidethesuppliesofenergy(andprecursors)necessaryforpostconjugantdevelopmentalevents.Smallautophagosomes(AP)forminconjugants;degeneratingmitochondriaareprominentamongtheinclusionsobservedinthesebodies.Soonafterseparationofpairs,largedenseAPappear,apparentlybycoalescenceandcondensationofthesmallerAP.These“mature”APgiveonlyaslightacidphosphatasereaction.ThenumberofAPslowlydeclinesduringpostconjugantdevelopment;about60hrafterseparationalltheAPhavebeendigested.Severalobservationssuggestthatthisautophagocytosisispartofthedevelopmentalprograminitiatedsoonaftermatingbegins:(1)ThefirstindicationsofAPformationoccurwhileconjugatingpairsarestillabletofeed,andthuscannotbeattributedtothestressofstarvation;(2)formationoflargenumbersofAPisratherabrupt,whereastheirdissolutionisverygradual,coveringmostofthenonfeedingperiod;and(3)thepatternofAPformationanddissolutionissimilarincellswhosenewmacronucleardevelopmenthasbeenpreventedbybriefhydroxyureatreatment.

[学科分类] 生物科学（综合）