Research On Biology, Chromosome Caryotype, LDH Isozymes, Embryonic Development, Artificial Breeding And Culture Techniques Of Mystus Nemurus

The purpose of this study is to investigate the biology, chromosome karyotype, LDHisozyme and embryonic development of Mystus nemurus, and to upgrade its artificialbreeding and culture techniques.A study of the karyotype of M. nemuru was conducted with kidney cells in vivo bythe air-drying method. Kidney cells of M. nemuru was studied with endo-injection ofPHA following short cultivation periods. Then colchicum was injected into live cells.Finally the cells were made into air-dried chromosome specimen. After Giemsa coloration,cell division was examined. There is a diploid chromosome number of 52 in catfish. Thekaryotype consists of 22 pairs of metacentric, 6 pairs of submetacentric and 24 pairstelocentric chromosome (NF=80). Total length of the chromosome is 74.8μm.The LDH isozyme of M. nemuru was compared with that of yellow catfishPeltebagrus fulvidraco using polyacrylamide gel electrophoresis method. The resultsindicated that the LDH in six organisms of two fish species were controlled by four sites.Though the isozyme composes and transferring rate of two fish species were the same inblood serum, they were different in other organisms such as liver, kidney, muscle, sexgland and eyes. Number of gene locus of LDH isozymes was polymer. Specificity oftissues was very obvious.Three combined chemicals including LHRH-A2, DOM and HCG were used in theartificial breeding of M. nemuru. The fertilized eggs were collected and cultivated in glassbowls. They were regularly checked, photoed and recorded. The fertilized eggs were oval,transparent and had a diameter of about 1.3-1.5 mm. Under water temperature 23-24℃,the embryo developed to the stage of blastula, gastrula, eye sac and heart beat at 2 h 50min, 4 h 30 min, 10 h 20 min, 17 h 20 min after fertilization respectively. Through total25 h embryo development, the larvae finally hatched with 2.95 mm whole length. Theyolk sac of larvae disappeared after 5 days post hatching.In this experiment, 55 pairs of M. nemuru and its red race were artificially induced inMay and June in 2004. The spawning rate was 80.5％and 3.88×10~5 eggs were obtainedwith a fertilizing rate of 71.1％. Later 1.6×10~5 fry were hatched with a hatching rate of 59％. The fry were stocked in the concrete ponds. At the end of this experiment, 47333fingerlings were totally obtained.