栉孔扇贝和虾夷扇贝杂交子代的细胞遗传学研究

Cytogenetic analysis on the hybrids from reciprocal crosses of Chlamys farreri × Patinopecten yessoensis

采用基因组荧光原位杂交（GISH）技术，结合改进的染色体滴片和压片法，对栉孔扇贝和虾夷扇贝远缘杂交正、反交子代4—8细胞胚胎及担轮幼虫的染色体构成及其变异进行了研究。结果表明，在染色体数目上，绝大部分正、反交子代早期胚胎的染色体数目为38条，与其双亲一致；在染色体构成上，绝大部分正、反交子代分别继承了栉孔扇贝和虾夷扇贝各一套染色体，为真正的杂交种，核型也为双亲染色体核型的综合：2n=6m＋29（sm,st）＋3t；正、反交子代之间在染色体构成上无明显差别，结果说明两种扇贝的属间杂交正反方向均能产生正常的杂交种胚胎，合子中两套染色体具有较强的亲合性。此外，杂交子代在胚胎发育早期还存在较小比例的染色体数目异常、不对称染色体继承等遗传学现象。在群体杂交所产生的正反交子代中还存在极小比例的疑为雌核发育的母本类型个体，但在单对杂交产生的正反交子代中均未见雌核发育的个体。本文就这些异常现象产生的可能原因进行了探讨。

The genomic constitution and its variation in embryos at early developmental stage of hybrid offspring from Chlamys farreri x Patinopecten yessoensis were studied by genome in situ hybridization and traditional chromosome preparation techniques. The result showed that the chromosome number in most of the hybrids from reciprocal crosses of Chlamys farreri x Patinopecten yesonensis was 38, which was accordant to that of their parents. Half of the chromosomes came from their maternal parents and haft from their paternal ones. The karyotype formula of the hybrids was 2n = 6m ＋ 29 （sm, st） ＋ 3t, which was almost exactly the combination of the karyotype of their parents. No obvious difference in genomic constitution was verified between hybrids from Chlamys farreri ♀ × Patinopecten yesonersis ♂ and from its reverse cross. These results may suggest that the reciprocal hybridization between the two scallop species can produce normal hybrid embryos and the two sets of chromosomes from both parents have great compatibility in the zygotes. There also existed some abnormalities in chromosome constitution in hybrid progenies such as haploid, triploid, aneuploid or non-equivalent chromosome inheritance. There were also some gynogenesis-like individuals in the hybrid offspring from the mass crosses of the two scallop species. But no was observed in the offspring from the pair mating crosses. The possible causes of these abnormalities were also discussed in this paper.