| The cytogenetic and molecular analysis technologies, such as karyotype, GISH, FISH, RAPD, ISSR, DNA sequencing, PCR-RFLP and isozyme electrophoresis, were applied to investigate the important phenomenon during the hybridization between Chlamys farreri and Patinopecten yessoensis. The results were as follows. 1. The direct observation of fertilization and early embryo development of hybrids from the cross of C. farreri and P. yessoensis showed that there was no pre-zygote isolation between the two scallop species. The fertilization between gametes of C. farreri and P. yessoensis and early embryo development of hybrids were usually quite normal with no obvious difference confirmed between the cross group and their parental control. But later studies with GISH analysis showed that there might be a subtype of fertilization barrier functioning in the hybridization between the twoscallop species------assortative fertilization. This subtype barrier was represented likethis: when the scallop eggs were fertilized competitively with both conspecific and heterospecific sperm, preference may occur with the conspecific sperm were usually preferentially selected. This may suggest that there is some difference in the sperm-egg recognition system between the two scallop species. 2.Karyotype analysis showed that most of the progenies from the cross of C. farreri× P. yessoensis were diploid hybrids with each individual possessing 38 chromosomes, Only small portion of hybrids proved to be haploid, triploid or aneuploidy. The karyotype formula of the hybrids was 2n=6m+11sm+18st+3t, which was almost the combination of the karyotype of their parents. Genome in situ hybridization technology was developed and optimized to investigate the genomic composition of hybrid scallops. The result showed that GISH analysis was able to distinguish the hybrids easily from their parents. Most of the hybrid progenies possessed half set of chromosomes (n=19), which can be labeled with genome probe of one parent, and...
|
PDF Full Text Request