黄条魳(Seriola aureovittata)染色体核型分析

以黄海北部沿海捕获的野生黄条(Seriola aureovittata)为实验材料,经过体内注射植物血球凝聚素(PHA)和秋水仙素,取头肾细胞,经空气干燥法制片,Giemsa染液染色后,观察黄条的染色体核型和特征.本研究分析了21条黄条的80个中期染色体核型,结果显示,黄条核型有48条染色体,2n=48占所观察分裂相的比例是81.25％;第1对染色体有次缢痕和随体.核型公式为2n=48=6sm+4st+38t,其染色体臂的数量为54,单倍体染色体总长度约为51.97 μm.黄条染色体核型比较独特,具有3对亚中部染色体和2对亚端部染色体;不同于以往报道的其他属鱼类的染色体核型特征.通过比较分析认为,黄条为进化上的高位类群中的特化类群.本研究为属鱼类的细胞遗传学研究提供了基础资料,并为黄条种质资源保护及未来人工养殖等奠定基础.

Study on the Karyotype of Yellowtail Kingfish (Seriola aureovittata)

Karyological study is a useful tool in exploring evolutionary mechanisms of fish because it provided basic information on the number,size and morphology of chromosomes.In this study we characterized the karyotype and chromosomal characteristics of the yellowtail kingfish Seriola aureovittata by examining metaphase spreads from head kidney cells of one-year-old fish artificially bred from wild broodstock in the Dalian coast of China.Chromosome samples were prepared through in vivo injection of phytohemagglutinin (PHA),olchicine-air drying technique,and Giemsa staining.A total of 80 mitotic metaphases from 21 individuals were analyzed,and 65 spreads showed 2n=48 chromosomes,which represented 81.25％ of the observed metaphases.The relative size of the chromosomes in this subspecies varied from (2.50±0.23)％ to (5.16±0.56)％.The long arm,short arm,and total length of the first submetacentric chromosomes were (1.81±0.09) μm,(0.87±0.03) μm,and (2.68±0.09) μm respectively.Two pairs of subtelocentric chromosomes were found in this subspecies.The length of their short arms was (0.55±0.04) μm and (0.39±0.06) μm,and that of the long arms was (2.10±0.06) μm and (1.87±0.07) μm.The diploid consisted of 4 submetacentric,6 subtelocentric,and 38 telocentric chromosomes,and the fundamental number of chromosome arms was 54.The first pair of chromosomes had secondary constriction and satellite.The karyotype formula for this species was determined to be 2n=48 =6sm + 4st + 38t.The total haploid chromosome length was approximately 51.97 μm.The fact that S.aureovittata has 3 pairs of submetacentric and 2 pairs of subtelocentric chromosomes distinguishes this species from other previously reported Seriola species.The comparison of karyotypes suggested that S.aureovittata might belong to an advanced and specific evolutionary group.Our study promoted the understanding of the specific karyotype evolution of the genus Seriola,and provided information on the polyploidy manipulation,hybridization,and sex control.