Long Xiaowen, Wu Xugan, Zhao Lei, Ye Haihui, Cheng Yongxu, Zeng Chaoshu
Department of Marine Biology and Technology, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China.
Centre for Research on Environmental Ecology and Fish Nutrition of Ministry of Agriculture, Shanghai Ocean University, Shanghai, China.
Front Physiol. 2018 Jan 4;8:1072. doi: 10.3389/fphys.2017.01072. eCollection 2017.
Salinity plays a key role affecting ovarian development, osmoregulation and metabolism of female Chinese mitten crab, during reproductive migration. In this study, female after their puberty molt were subjected to four salinities of 0, 6, 12, and 18‰ for 40 days to investigate the salinity effects on their ovarian development as well as a range of important physiological parameters. Elevated salinity accelerated the ovarian development with ovigerous crabs found at salinity treatments of 12 and 18‰ despite no copulation had occurred. Meanwhile the survival rate of female crabs showed a decreasing trend with increasing salinity. Higher salinity also led to increased hemolymph Na, K, Ca, Cl, and Mg concentrations. The 6‰ treatment had the highest contents of hemolymph total and major free amino acids while the Na/K -ATPase activity in the posterior gills was the lowest among treatments. Total n-3 polyunsaturated fatty acids (∑n-3PUFA) and n-3/n-6 PUFA ratio in the anterior gills showed a decreasing trend with salinity while 18‰ had the highest ∑PUFA and ∑n-6PUFA. The ∑n-3PUFA content and n-3/n-6 PUFA ratio of the posterior gills showed a fluctuating pattern and the highest value was detected at 0‰, while an increasing trend was found for the ∑n-6PUFA with increasing salinity. The hemolymph glucose showed a decreasing trend with increasing salinity and the highest total cholesterol in hemolymph was detected at 12‰. The 18‰ treatment had the highest levels of hemolymph γ-glutamyltransferase, alkaline phosphatase and acid phosphatase, as well as glucose, urea and acid phosphatase in hepatopancreas while the highest hemolymph superoxide dismutase and malondialdehyde were detected at 0‰. Overall, the results showed that salinity increase from freshwater to brackish conditions led to lower metabolism, accelerated ovarian development, and the appearance of ovigerous crabs without copulation in female post puberty molt.
盐度在中华绒螯蟹雌蟹生殖洄游期间对其卵巢发育、渗透压调节和新陈代谢起着关键作用。在本研究中，对青春期蜕壳后的雌蟹分别施以0‰、6‰、12‰和18‰的四种盐度处理，持续40天，以研究盐度对其卵巢发育以及一系列重要生理参数的影响。盐度升高加速了卵巢发育，在12‰和18‰盐度处理组中发现了抱卵蟹，尽管此时尚未发生交配。与此同时，雌蟹的存活率随盐度升高呈下降趋势。较高的盐度还导致血淋巴中钠、钾、钙、氯和镁的浓度增加。6‰处理组血淋巴中总游离氨基酸和主要游离氨基酸含量最高，而后鳃中钠钾ATP酶活性在各处理组中最低。前鳃中总n-3多不饱和脂肪酸（∑n-3PUFA）和n-3/n-6多不饱和脂肪酸比值随盐度升高呈下降趋势，而18‰处理组的总多不饱和脂肪酸（∑PUFA）和总n-6多不饱和脂肪酸含量最高。后鳃中∑n-3PUFA含量和n-3/n-6多不饱和脂肪酸比值呈波动模式，在0‰时检测到最高值，而总n-6多不饱和脂肪酸含量随盐度升高呈上升趋势。血淋巴葡萄糖含量随盐度升高呈下降趋势，血淋巴中总胆固醇含量在12‰时检测到最高值。18‰处理组血淋巴γ-谷氨酰转移酶、碱性磷酸酶和酸性磷酸酶水平最高，肝胰腺中的葡萄糖、尿素和酸性磷酸酶含量也最高，而血淋巴中超氧化物歧化酶和丙二醛含量在0‰时检测到最高值。总体而言，结果表明，从淡水到微咸水条件下盐度的增加导致新陈代谢降低、卵巢发育加速，以及青春期蜕壳后的雌蟹出现未交配的抱卵蟹。
