This experiment was conducted to examine the effects of salinity fluctuation frequency on the growth, molting rate and hemolymph 20-hydroxyecdysone （20-HE） concentration for juvenile Fenneropenaeus chinensis with an...This experiment was conducted to examine the effects of salinity fluctuation frequency on the growth, molting rate and hemolymph 20-hydroxyecdysone （20-HE） concentration for juvenile Fenneropenaeus chinensis with an initial wet body weight of 1.115 g±0.012 g. The salinity of the control treatment （represented by DO） was 28 throughout the experiment, whereas treatments D2, D4, D6 and D8 were subjected to different salinity fluctuation frequencies of 2, 4, 6 and 8 d, respectively. The range of salinity fluctuation was 4. The salinity in treatments D2, D4, D6 and D8 was kept at 28 for 2, 4, 6 and 8d, respectively; each original salinity was decreased abruptly to salinity 24, which first lasted for another 2 d and was then raised to its initial value 28. This constituted a salinity fluctuation cycle and afterwards the cycle repeated. It was found that： 1） The weight gain of shrimp in treatment D4 was 202.9% and significantly higher than that in treatment DO （P〈0.05）. The molting rate in treatment D2 was the lowest, while that in treatment D6 was the highest and significantly higher than those in treatments DO and D2 （P〈0.05）. 2） The hemolymph 20-HE concentration of shrimps in all treatments was at low levels and increased first gradually during the inter-molt period and then increased sharply. It reached a peak value during the pre-molt stage, and then decreased abruptly during the post-molt stage when the lowest level occurred. 3） During the post-molt stage, the hemolymph 20-HE concentration in treatment D2 was 7.47pg μL^-1 and significantly higher than that in treatment DO （P〈0.05）. There were, however, no significant differences in hemolymph 20-HE concentration among all five treatments during the inter-molt stage （P〉0.05）. During the pre-molt stage, the hemolymph 20-HE concentration in treatment D6 was significantly higher than that in treatment DO （P〈0.05）, whereas the hemolymph 20-HE concentration in treatment D2 was significantly lower than that in other treatments （P〈0.05）. Adequate salinity fluctuation promoted the molting rate through increasing hemolymph 20-HE concentration at the pre-molt stage.展开更多
基金supported by funds from the National Natural Science Foundation of China (Grant No. 30571441)the Project of Reward Research Foundation for Talented Young and Middle Aged Scientists of Shandong, China (Grant No. 2006BS07002)the National Great Project of Scientific and Technical Supporting Programs Funded by the Ministry of Science and Technology of China in the 11th Five-Year Plan (Grant No. 2006BAD09A07)
文摘This experiment was conducted to examine the effects of salinity fluctuation frequency on the growth, molting rate and hemolymph 20-hydroxyecdysone （20-HE） concentration for juvenile Fenneropenaeus chinensis with an initial wet body weight of 1.115 g±0.012 g. The salinity of the control treatment （represented by DO） was 28 throughout the experiment, whereas treatments D2, D4, D6 and D8 were subjected to different salinity fluctuation frequencies of 2, 4, 6 and 8 d, respectively. The range of salinity fluctuation was 4. The salinity in treatments D2, D4, D6 and D8 was kept at 28 for 2, 4, 6 and 8d, respectively; each original salinity was decreased abruptly to salinity 24, which first lasted for another 2 d and was then raised to its initial value 28. This constituted a salinity fluctuation cycle and afterwards the cycle repeated. It was found that： 1） The weight gain of shrimp in treatment D4 was 202.9% and significantly higher than that in treatment DO （P〈0.05）. The molting rate in treatment D2 was the lowest, while that in treatment D6 was the highest and significantly higher than those in treatments DO and D2 （P〈0.05）. 2） The hemolymph 20-HE concentration of shrimps in all treatments was at low levels and increased first gradually during the inter-molt period and then increased sharply. It reached a peak value during the pre-molt stage, and then decreased abruptly during the post-molt stage when the lowest level occurred. 3） During the post-molt stage, the hemolymph 20-HE concentration in treatment D2 was 7.47pg μL^-1 and significantly higher than that in treatment DO （P〈0.05）. There were, however, no significant differences in hemolymph 20-HE concentration among all five treatments during the inter-molt stage （P〉0.05）. During the pre-molt stage, the hemolymph 20-HE concentration in treatment D6 was significantly higher than that in treatment DO （P〈0.05）, whereas the hemolymph 20-HE concentration in treatment D2 was significantly lower than that in other treatments （P〈0.05）. Adequate salinity fluctuation promoted the molting rate through increasing hemolymph 20-HE concentration at the pre-molt stage.
