Studies On Annual Reproductive Cycle Of Female Pelteobagrus Vachelli In Jia-Ling River

Pelteobagrus vachelli, which belongs to Silurformes, Bagridae, pelteobagrus, is one important economical fish in the upper reaches of the Yangtze River. In this paper, the micro-structure as well as the annuation discipline of organizational AKP,ACP activities and RNA/DNA ratio were studied for probing into the breeding cycle of Pelteobagrus vachelli.The main results were summarized as follows:1. Biologic character of the ovary of Pelteobagrus vachelliThe ginadoaomatic index (GSI) of Pelteobagrus vachelli was gradually increased with the gonad development, which appeared a rapid heighten trend at the end of April and reached the maximum 15.40% in the mid-May while the GSI declined dramatically after July and had no significant difference from August to December.The hepatopancreas index (HSI) of Pelteobagrus vachelli showed a slowly increasing trend and achieved 3.45% in mid-April. It gradually reduced with the gonad development and dropped to 2.35% in the spawning period and appeared a gradual upward trend after spawning in july and achieved the maximum 3.73% in December.With the gonad development, the fullness (F) appeared a gradual downward trend from March to May and dropped to the minimum 0.99% in June , then gradually increased to 1.32% in August.The average egg diameter of Pelteobagrus vachelli was gradually increased with the gonad development, which occoured a rapid heighten trend from end-April to mid-May. There was an obvious peak from May to July which reflected the final maturing stage of oocyte and 20.6% the oocytes had developed into the fifth phase. After spawning in July, the average egg dimeter dramatically decreased.2. The micro-struture of gonad development of Pelteobagrus vachelli.Pelteobagrus vachelli had a pair of long-sack-type ovaies. its ovarian was divided into six periods and its oocyte divided into six phases by dissecting its ovary and observing its histological slice. The gonad development was in the second period from October to February of next year, the third period from April to May; the fourth period from May to July and the sixth period from Augest to September.Yolk nucleus and follicular cells occurred in the-second-phases oocyte ; vacuole , which number and layers were increasing with the gonad development, occurred in the-thid-phase egg. yelk particles were full of the-fourth-phase oocyte in which the micropyle and the micropyle of cell ocuured.3. Histological studiese on the gonad developmengt of Pelteobagrus vachelliThe protein content in ovary of Pelteobagrus vachelli was gradually increased with the gonad development, which had rased from 97.23±4.05g/ml in January to the maximum 131.93±2.66g/ml in May.It decreased from June and drop to the minimum 70.19 g/ml in September, and then had no variety in the following months. The hepatic protein content of Pelteobagrus vachelli was gradually increased with the ovary development, which had reached to the maximum 134.52±1.44 g/ml in mid-April and started to decline and dropped to the minimum 75.36±7.98g/ml in June.The AKP activities in both ovary and liver of Pelteobagrus vachelli were gradually increased with the ovary development, which reached to the maximum 35.21±2.52U/gprot,60.45±7.89 U/gprot respectively in mid-April. The AKP activity in ovary started to decline from mid-April and dropped to the minimum 3.66U/gpro in spawning time, it had no remarkable difference from July to Octoberr while re-increased in November. The AKP activity liver dropped to the minimum 8.37±1.20 U/gprot in end-July, and then had no obvious change in the following months while re-increased in December.The ACP activities in both ovary and liver of Pelteobagrus vachelli were gradually increased with the ovary development from January to April, which reached to the maximum 56.21±7.66 U/gprot and 313.67±17.74 U/gprot respectively in mid-April. It started to dramatically decrease from mid-April and droped to the minimum 9.50±0.33 U/gprot and 76.43±3.99U/gprot respectively in spawning time. The ACP activity in ovary re-increased in Augest and liver in which rei-ncreased in June reached 208.90 U/gprot in August and declined from September to November, then rised in December.The RNA content of the ovary of Pelteobagrus vachelli had increased from 7.72±1.20 mg/g to 9.63±1.22mg/g from January to the end-April, then started to decline and dropped to the minmum in July and rised from August. It increased from July and reached the maximum 6.31 mg/g .The DNA content of the ovary of Pelteobagrus vachelli had increased from 0.36±0.05mg/g to 0.42±0.10mg/g from January to March, then begined to decline and dropped to the minmum 0.1 l±0.05mg/g in June. The RNA/DNA ratio in ovary was gradually increased with the ovary development, which reached the maximum 12.71±3.10 in the mid-May, it started to decline in June while started to reincrease in Augest and had no significant differences in the following months.The DNA content appeared a mini-raise from January to mid-April and then begun to decline. the RNA content and RNA/DNA ratio raised from 4.62±0.15mg/g and 2.04±0.35 to the maximum 9.24±0.22mg/g and 3.15±0.33 respectively from January to May and showed a downward trends from early June and turned an upword trends from November.According to studying biology, micro-struture and histology of Pelteobagrus vachelli , the results showed that the ovay of Pelteobagrus vachelli was in flourish phase from mid-April to mid-May and the breeding season was between mid-May and mid-July. The degradation and rehabilitation period was from August to September.