Study Of Triploid Induction In Scallop Patinopecten Yessoensis By Hyperosmotic Treatment

Triploid breeding of shellfish is increasingly important and as a vital economicspecies in China, Patinopecten yessoensis was studied on fertilization withfluorescent microscope.A new method,hyperosmotic treatment,was used inP.yessoensis triploid induction by blocking polar body I（IPB2）.This paper focused onthe suitable induction parameters,fertilization development process,geneticanalysis,ploidy investigation,growth and survival during the stage of larvaldevelopment.All information should be taken into consideration in breeding ofscallop.The main contents consist of the following three parts.1. Cytological observation on Patinopecten yessoensis with fluorescencemicroscope.With the help of a fluorescence microscope,the fertilization of Patinopectenyessoensis stained with DAPI was observed.Unfertilized mature eggs showspherical shape,and nuclear phase was mostly at metaphase of meiotic I. After theactivation of sperms,eggs finished MI and MII and released the first and the secondpolar body.After the approach and association of the female and male pronuclei,thediploid zygote nucleus was then formed.Asynchronism and retardance in zygotedevelopment are remarkable.2. Induction of Patinopecten yessoensis triploid by hyperosmotic treatment andnursery.In order to get the optimal induction parameters, different hyperosmotictreatments(when the first PB1appears、 the ratio of PB1reaches30%and50%,respectively、the first PB2appears、the ratio of PB2reaches20%; salinity of35、40、45、50、55、60、65and70‰;duration time of15min，20min，25min，30minand35min)were carried by inhibiting PB1or PB2releasing.Results showed that thezygotes treated for20min with a hyperosmotic solution of60salinity when the first PB2appears can yield the highest triploidy rate72.12%.3.Nursery and spat cultivation in triploids of Patinopecten yessoensisThe same experimental setting as part2was applied to optimize the inductionparameters of Patinopecten yessoensis triploid by inhibiting PB2releasing.Resultsshowed the zygotes treated for20min with a hyperosmotic solution of60salinitywhen the first PB2appears can yield a fine triploidy rate of72.12%. The change ofinduction parameters concernd asynchronism and retardance in hybrid development.