银鲳(Pampus argenteus)染色体标本制备及其核型研究

Chromosome Samples Preparation and Karyotype Analysis of Pomfret (Pampus argenteus)

关键词:  银鲳  鳃组织  染色体  核型

Key words:  Pampus argenteus  Pectoral gills  Chromosome  Karyotype

摘要:

为保护银鲳(Pampus argenteus)种质资源、为遗传育种提供理论基础，本研究在银鲳鳃组织细胞处于高活性状态下进行染色体标本制备，采用热滴定法制备银鲳染色体标本，并分析其染色体核型，初步探讨了银鲳的进化程度。实验银鲳为70–80日龄，体长为7–9 cm，设置3个重复组，每组3尾银鲳。将银鲳暂养于秋水仙素终浓度为0.005%的海水中4 h，剪取鳃组织制备染色体标本。该实验方法避免了对银鲳离水操作造成的物理伤害，确保银鲳在活力正常的前提下获得实验样本。染色体核型分析表明，银鲳二倍体染色体数为2n=48，核型为2n=2SM+10ST+36T，其染色体臂数(NF)为50。未发现与性别相关的异型染色体。其核型符合典型的高位类群鱼类的核型特征。由于研究对象为未性成熟银鲳幼鱼，无法分辨雌雄，因此，尚不能确定银鲳是否存在异形性染色体，有待性成熟之后进一步验证。

Abstract:

In order to protect the germplasm resources of pomfret (Pampus argenteus) and provide some theoretical basis for its genetic breeding, this research was carried out by thermal titration method for preparing chromosome specimens of pomfret in living state and analyzed its chromosome karyotype. Finally, the evolutionary taxonomy of pomfret had been preliminary discussed. The pomfret involved in this experiment were juveniles 70-80 days old and their sizes ranged in 7.0–9.0 cm. They were divided into three groups, each group of three fishes, and kept in seawater containing 0.005% colchicine for 4 hours. Then, each group took three individuals, and a part of the gill tissues were sheared for preparing the chromosome specimens. The methods in this experiment prevented the pomfret from the physical damage caused by the operations off the water and ensured the experimental materials were obtained from pomfret with normal vitality. The analysis of chromosome karyotype showed that there were 48 telocentric chromosomes in the diploid and their karyotype formulae is 2n = 2SM + 10ST + 36T, namely, there were one pair of submetacentric chromosomes (SM) and 5 pairs of acrocentric chromosomes (ST) and 18 pairs of telocentric chromosomes (T), and their fundamental number (NF) was 50. There was no visible evidence of polyploidy chromosome and sex chromosome. and the karyotype was in accordance with the typical characters of karyotype in the higher group of fish evolutionary taxonomy. As the research objects were juveniles which had the immature sexual gland, and were unable to distinguish between male and female, it is uncertain whether there is a sexual chromosome in pomfret, and it needs to be further studied when the gonads are ready.