尼罗尖吻鲈和鳜鱼染色体组型分析及比较

THE COMPARISON AND ANALYSIS OF CHROMOSOME KARYOTYPE OF THE NILE PERCH (LATES NILOTITUS) AND MANDARIN FISH (SINIPERCA CHUATSI)

采用PHA、秋水仙碱腹腔或背部肌肉注射,活体培养法,以前肾为材料,低渗-空气干燥法制片,进行染色体观察,运用Micromeasure version3.3染色体分析软件和Photoshop7.0软件首次分析了尼罗尖吻鲈的染色体数目和核型,并同鳜鱼染色体数目和核型进行了分析比较,对今后拟采取的杂交尝试提供理论基础。结果显示:尼罗尖吻鲈染色体众数为2n=48,核型公式为2m+4sm+12st+30t,染色体臂数(NF)为54;鳜鱼染色体众数为2n=48,核型公式为6sm+12st+30t,染色体臂数(NF)亦为54;两种鱼染色体短臂上均无随体,单臂染色体较多。分析表明尼罗尖吻鲈与鳜鱼杂交成功的可能性较大。

The Nile perch （Lates niloticus） naturally distribute in Africa and it was firstly introduced into China from Egypt in 2003. Nile perch is a good species for aquaculture, as it has excellent traits with rapid growth, good meat quality and huge potential in international market. After the fish was imported and stocked in Freshwater Fisheries Research Center, the center staff studied on the biological characters, growth performance, nutritional components and culture system of Lares niloticus,but some important genetic characteristics have not been involved, such as chromosome and other cytogenetical traits. Mandarin fish （Siniperca chuatsi） is a famous domestic species with good quality and belongs to the same family Perciformes as Nile perch. The karyotype of Lares niloticus is firstly reported in this paper and compared with Siniperca ehuatsi. The main propose of the study focused on protection of germplasm resources, systemic evolution and evolutionary status of Nile perch. Also, some basic date would be provided to discuss the possibility for hybridization of Lares niloticus and Siniperca chuatsi through this study. The mitotic chromosomes and karyotype of Nile perch and Mandarin fish were studied using PHA and colchicine intramuscular injection in the back or abdominal cavity of the Nile perch and mandarin fish. This two species was vivo-cultured and renal tissues were used with short-term culture and treated with air-drying technique referred the method used by Lin Hao-Ran,et al. and a slight improved. The data was analysed by using two softwares： Micromeasure version 3.3 and Photoshop 7.0. The results showed that the karyotype of Nile perch was 2n = 48,2m ＋4sm ＋ 12st ＋ 30t,NF = 54 and the kayotype of Mandarin fish was 2n = 48,6sm ＋ 12st ＋ 30t,NF = 54. The number of chromosomes was same, and there were no satellites in the arms of all chromosomes in these two species. The Lates niloticus had one pair of metacentric chromosome more than those of Mandarin fish. They all had 6 pairs of sub-telocentric chromosome and 15 pairs of tclocentric chromosome and single arm chromosomes were abundant. The karyotypes of Lates niloticus and Siniperca chuatsi were similar,which indicted that these two species had very close relationship. It is possible to get the hybrid of Lates niloticus and Siniperca chuatsi and gives an academic basic for the cross breeding research. It must be mentioned here that the juvenile of Nile perch is very sensitive for injection, most of them were dead after intramuscular injection. It is sure that the ideal results can be got by using adult fish as experimental material.