THE COMPARISON AND ANALYSIS OF CHROMOSOME KARYOTYPE OF THE NILE PERCH(LATES NILOTITUS)AND MANDARIN FISH(SINIPERCA CHUATSI)
尼罗尖吻鲈和鳜鱼染色体组型分析及比较

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 Lates 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 Lates niloticus is firstly reported in this paper and compared with Siniperca chuatsi. The main propose of the study focused on protection of germ plasma resources, systemic evolution and evolutionary status of Nile perch. Also, some basic date would be provided to discuss the possibility for hybridization of Lates 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 were dead after intramuscular injection. It is sure that the ideal results can be got by using adult fish as experimental material.