| Schizothorax chongi, which belongs to Schizothoracinae, Cyprinidae, is one of the most important economical cold water fish, uniquely lived in China. In this paper, the reproductive biology of S. chongi was discussed. The results indicated as follows:1. The detection of biochemical composition and enzymes activities in vivo tissues of S.chongi with the gonad maturityGonadosomatic index (GSI) was gradually rising with the gonad maturity and achieved the maximum at the stage V, arriving at 8.78+3.93 and 5.54±2.03 respectively. Hepatopancreas index (HSI) of male also reached maximum of 2.13±0.22 at stage V, however, the female gonadal coefficient of fat (CF) in stage IV~+ reached the peak of 14.61±3.44.Physiological and biochemical indices were detected in different tissues during gonad development and maturation. The results show that: tissue water contents changes very little in different stages. Muscle glycogen has a small change, but liver glycogen and glucose showed a drastic change with the gonad maturity. In the early stages, ovarian demand for a great deal of protein but little lipid, the resource of protein and lipid accumulated in vivo Came from other organizations; In the later stages, mature ovarian reduced the demand for protein, but the demand for lipid increased dramatically, and the lipid mainly relies on internal supply at this stage; Testicular lactate dehydrogenase (LDH) activity was closely related to the sperm mature metabolism, and gradually increased with the mature sperm; Lipase (LPS) activity in gonads along with the gonad maturity and gradually increased; Nitric oxide synthase (NOS) activity in the organizations are "pulse" of expression before gonads mature, it may be a reproductive signal.2. Histological and untrastructural studies on the gonad development of S.chongiThe microstructure of the gonad development and the intrastructure of stem cells of S. chongi were systemic depicted. According to the morphological and histological features, both testis and ovary development in S. chongi can be divided into six stages, and the change of female cells can be divided into six phases. There are several phases in the spermatogenesis, namely are primary spermatogonium,secondary spermatogonium,primary spermatocytes,secondary spermatocytes,spermatid and mature sperm. The testis was lobular type. There are some somatic cells around the testis, such as sertoli cell and leyding cell, fibroblasts and so on. Various spermatogenic cells locate in the central lobule. Primary spermatogonia and secondary spermatogonia have many differences in cell size, organdie types and quantities as well as the distribution of regions in the testis. Chromatoid body was presented in most of germ cells, except for sperm. Nuclear bubbles were formed in the growth of sperm cells, and disappeared with the sperm maturation. The spermatozoon lacks an acrosome in its head which mainly occupied by nuclear. The tail mainly composed by the axoneme which present a typical "9 +2" structure.3. Study on the artificial propagation of 5. chongiSperm's fast movement time and life time amounting to 43±8 s and 180±36 s separately in natural river water; The duration in which sperm kept fast motility and the sperm life span was basically similar in NaCl and glucose solutions; Sperm acquisition of high motility in 0.6% NaCl solution and 0.4% glucose solution, the average fast motility time was 54 s and 52 s, and the average life time was 1508 s and 1760 s separately; The sperm which lost their motility would reactivate motility if joined the water.During the year 2005～2006, in order to study the technology of artificial propagation, four kind of different combination hormones were injected separately into 180 mature wild S.chongi, which have been artificial domesticated in running water fishpond. Altogether, the quantity of fertilized eggs laid by breeding fish was 500,000 and the 90,000 larva were hatched out. The water temperature scope which artificial propagate can be successfully implemented was form 13℃to 18℃. The optimum combination of exterior hormones was: the combination of PG and HCG, with two injections, the first time injection dosage was (5mg+600IU)/kg fish body weight, and the second time was (12mg+1000IU)/kg fish body weight, the reactive time was about 85~98 h under the water temperature 13～18℃.Under the water temperature 17±1℃, the embryonic development process took 124 hours form fertilization to hatching with the average cumulative temperature of 2108.00 h·℃. The yolk-sac larvae started to swim horizontally with inflation the pneumatic cyst 9 days after hatching. The embryonic development process could be divided into 6 stages, including fertilized egg stage, cell division stage, blastula stage, gastrula stage, neural stage and organ formation stage, and contained twenty-four developing phrases as other teleost. each of their characteristic was described. The developmental speed of embryo and yolk-sac larva of S.chongi was quicker in the Schizothoracinae, later would be specially more obvious in the muscle effective phase; The frequency of palpitation was not simple linear growth from slowly to the quickly, but was a curve change process with speed interaction; each stage of early development has different sensitivity to (peripheral environment, the gastrula stage was more sensitive than other stages. |
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