The Second Meiosis Occurs in Cytochalasin D-Treated Eggs of Corbicula leana Even Though It Is Not Observed in Control Androgenetic Eggs because the Maternal Chromosomes and Centrosomes Are Extruded at First Meiosis

Developmental Biology

K. Ookubo¹  A. Komaru¹  R. Ishibashi¹  M. Kiyomoto¹ 

[1] Faculty of Bioresources, Mie University, Tsu, Mie, 514-8507, Japan

关键词: bivalvia;    androgenesis;    cytochalasin D;    second meiosis;    tubulin;    centrosomes;    spindle;    pronuclei;   

DOI  :  10.1006/dbio.2002.0590

学科分类：生物科学（综合）

来源: Academic Press

【 摘 要 】

ThehermaphroditicfreshwaterclamCorbiculaleanareproducesbyandrogenesis.Inthecontrol(androgeneticdevelopment),allmaternalchromosomesandmaternalcentrosomesatthemeioticpoleswereextrudedasthetwofirstpolarbodies,andsubsequently,secondmeiosisdidnotoccur.But,inC.leanaeggstreatedwithcytochalasinD(CD)toinhibitpolarbodyextrusion,thesecondmeiosisoccurred.Atmetaphase-I,thespindleshowedthetypicalbipolarstructureandtwospheroidcentrosomeswerelocatedatitspoles.Allthematernalchromosomesweredividedatanaphase-I,buttheywerenotextrudedaspolarbodiesduetotheeffectsofCD.Aftercompletionoffirstmeiosis,thematernalcentrosomessplitintofour.Atthesecondmeiosis,twinortetrapolarspindleswereformedandtwogroupsofmaternalchromosomesdividedintofoursetsofchromosomes.Afterthesecondmeiosis,thespindledisassociatedandthefourmaternalcentrosomesdisappeared.Fourgroupsofmaternalchromosomestransformedintothefourfemalepronuclei.Maleandfemalepronucleibecamemetaphasechromosomesofthefirstmitosis.ThepresentstudyclearlyindicatesthattypicalmeiosissystemsstillproceedinandrogenetictriploidC.leana.Weconcludethattheandrogeneticformmayhavearisenfromthemeioticform.

【 授权许可】

Unknown