Studies On Idioplasmic Character Of Silurus Asotus In Dalai Lake

Dalai Lake is the 5th large freshwater lake in China, and the largest one in Inner Mongolia, which is abundant in wild freshwater fish species. Since it is far away from the big cities and the industrial areas, it has not suffered any pollution and has become an important commercial fishing base in Inner Mongolia, with the main species of wild freshwater fish as Cyprinus capion, Carassius auratus gibelio, Culter erythropterus Basilewsky, Erythroculter Mongolicus, Hemiculter leucisulus, Esox reicherti Dybowski, Silurus Asotus and so on. In the past years, many researches were done on the wild freshwater fishes, but there are few results on their Idioplasmic Character, which is unfavorable of the protection and development of the northern freshwater fish resources in China and is far from satisfying the requirements for the establishment of the Idioplasmic standard and the management of long-term scientific catch. This paper studies the main biological character, the genetic character of chromosomes, the physiology and biochemistry of genetic Character and the nutritional physiology and biochemistry of the muscle of the Silurus Asotus in Dalai Lake. The result shows as follows: 1. The main biological character: Silurus Asotus in Dalai Lake is described from external form,countable character and metrical proportional character by the observation of its exterior character and the measurement of traditional morphology. 2. The genetic character of chromosomes: The chromosomes of Silurus Asotus were prepared directly from the kidney cell of lively fish. The analysis of the result shows that there are 58 chromosomes in diploid number of the Silurus Asotus, and there are 24 metacentric chromosomes (m), 20 submetacentric chromosomes (sm), 10 subtelocentric chromosomes (st) and 4 telocentric chromosomes (t). Thus the karyo formula is 2N=24m+20sm+10st+4t, NF=120. 3. The physiology and biochemistry of genetic Character: The differentiated expression pattern of 3 isozymes: Lactate dehydrogenase (LDH), malate dehydrogenase (MDH) and superoxide dismutase (SOD) were investigated in 5 different tissues (eye, heart, liver, muscle and brain) of Silurus Asotus. Isozymes were resolved by vertical polyacrylamide gel electrophoresis (PAGE) and then detected by specific histochemical staining respectively. The result shows that isozymes in the Silurus Asotus apparently exhibit a tissue specific differentiate expression. In addition, its physiological significance was discussed and analyzed in relation to the tissue specific expressive distribution of the isozymes. 4. The nutritional physiology and biochemistry of the muscle: The result shows that the nutritional composition of the muscle is as follows: Gross moisture: 76.66%, gross crude protein: 17.53%, gross fat: 4.83% and gross ash: 1.04%. Furthermore, Silurus Asotus in Dalai Lake was compared with the other Silurus on their nutritional composition. The result shows that Silurus Asotus is a kind of fish with higher protein, higher fat.