栉江珧染色体制备及核型分析

Chromosome Preparation and Karyotypes Analysis of Both Male and Female Atrina pectinata

关键词:  栉江珧  染色体核型  异形染色体  分类

Key words:  Atrina pectinata  Chromosome karyotypes  Heterotypic chromosome  Phylogeny

摘要:

为了解栉江珧(Atrina pectinata)的细胞遗传学特征，取暂养促熟的雌雄亲贝共12枚为研究对象，通过调节暂养水温、采用鳃丝及鳃丝对应部位创面的愈合增生组织为染色体制备材料来改良染色体制备方法，采用常规的热滴片法制备出大量形态好且分散均匀的染色体标本，并进行染色体核型分析。结果显示，适度调节暂养水温和给鳃组织制造微创并以创面愈合增生组织为染色体制备材料均能有效增加组织细胞的分裂增生能力，为染色体制备提供了充足的材料；栉江珧二倍体染色体数目2n=34，雄性染色体组型为2n = 8m+10sm+16st，雌性染色体组型为2n = 6m+10sm+18st，染色体组型中，雌雄两性中期分裂相的染色体排序基本一致，都有1对染色体相对长度明显大于其他染色体；两性染色体组型有两处明显不同，其一，雄性第14对染色体为中着丝粒染色体，而雌性相对应的是亚端着丝粒染色体；其二，雄性栉江珧相对长度最大的染色体存在异形情形，雌性最大的染色体对则为同形，基本确定栉江珧存在初级的性染色体分化，属于XX/XY型性别决定方式。大型贝类染色体制备方法的改进将有助于丰富贝类细胞遗传学和分类学的研究内容。

Abstract:

The pen shell, Atrina pectinata, has high commercial and scientific research value because of the lack of large-scale culture in China. In recent decades, many problems such as overfishing, deterioration of marine eco-environment, and failure of artificial seedling breeding, have drastically reduced the amount of wild sources. However, there are few reports on A. pectinata systematic classification and no karyotype reports until now. To explore the cytogenetical characters and identify the status of germplasm resources of A. pectinata in northern China, by adjusting the water temperature of temporary rearing, and using the healing hyperplasia tissue of gills for chromosomal investigation, we improved the methods of chromosome preparation, and obtained many well-spread mitotic chromosomal plates of seven male and five female A. pectinata. The results revealed that a certain degree of temperature-change stress during temporary rearing could promote the proliferation of somatic cells effectively in the short term; gill-healing hyperplastic tissue has mass proliferation of cells in mitotic metaphase. The karyotypes of both sexes were examined separately. A. pectinate has 17 pairs of chromosomes (i.e. n=17, and 2n=34); there were obvious differences in karyotype between males and females; male karyotype formula is 2n=8m+10sm+16st；female karyotype formula is 2n=6m+10sm+18st. The first pair of the particularly larger chromosomes were heterotypic in male somatic cells; the No.14 pair of chromosomes was metacentric in males but telocentric in female metaphase somatic cells; the primary sex-determination mechanism is XX/XY type. The newly improved methods for chromosome preparation could be beneficial to large-scale shellfish germplasm identification and classification.