Luo Jiaxiang, Ren Chen, Zhu Tingting, Guo Chen, Xie Shichao, Zhang Yingying, Yang Zheng, Zhao Wenli, Zhang Xiangsheng, Lu Jingjing, Jiao Lefei, Zhou Qicun, Tocher Douglas R, Jin Min
Laboratory of Fish and Shellfish Nutrition, School of Marine Sciences, Ningbo University, Ningbo 315211, China.
Guangdong Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Sciences, Shantou University, Shantou 515063, China.
Anim Nutr. 2022 Nov 15;12:297-307. doi: 10.1016/j.aninu.2022.10.004. eCollection 2023 Mar.
The physiological processes involved in adaptation to osmotic pressure in euryhaline crustaceans are highly energy demanding, but the effects of dietary lipids (fat) on low salinity adaptations have not been well evaluated. In the present study, a total of 120 mud crabs (, BW = 17.87 ± 1.49 g) were fed control and high-fat (HF) diets, at both medium salinity (23‰) and low salinity (4‰) for 6 wk, and each treatment had 3 replicates with each replicate containing 10 crabs. The results indicated that a HF diet significantly mitigated the reduction in survival rate, percent weight gain and feed efficiency induced by low salinity ( < 0.05). Low salinity lowered lipogenesis and activated lipolysis resulting in lipid depletion in the hepatopancreas of mud crabs ( < 0.05). Thus, HF diets enhanced the process of lipolysis to supply more energy. In the gills, low salinity and the HF diet increased the levels of mitochondrial biogenesis markers, the activity of mitochondrial complexes, and the expression levels of genes related to energy metabolism ( < 0.05). Consequently, the positive effects of the HF diet on energy metabolism in mud crabs at low salinity promoted osmotic pressure regulation. Specifically, significantly higher haemolymph osmotic pressure and inorganic ion content, as well as higher osmotic pressure regulatory enzyme activity in gills, and gene and protein expression levels of NaK-ATPase were observed in crabs fed the HF diet at low salinity ( < 0.05). In summary, high dietary lipid levels improved energy provision to facilitate mitochondrial biogenesis, which increased ATP provision for osmotic pressure regulation of mud crabs. This study also illustrates the importance of dietary lipid nutrition supplementation for low salinity adaptations in mud crabs.
广盐性甲壳类动物适应渗透压的生理过程需要消耗大量能量，但膳食脂质（脂肪）对低盐度适应的影响尚未得到充分评估。在本研究中，总共120只青蟹（体重 = 17.87 ± 1.49克）分别在中等盐度（23‰）和低盐度（4‰）条件下投喂对照饲料和高脂（HF）饲料6周，每个处理有3个重复，每个重复包含10只螃蟹。结果表明，高脂饲料显著减轻了低盐度引起的存活率、体重增加百分比和饲料效率的降低（P < 0.05）。低盐度降低了脂肪生成并激活了脂肪分解，导致青蟹肝胰腺中的脂质消耗（P < 0.05）。因此，高脂饲料增强了脂肪分解过程以提供更多能量。在鳃中，低盐度和高脂饲料增加了线粒体生物发生标志物的水平、线粒体复合物的活性以及与能量代谢相关基因的表达水平（P < 0.05）。因此，高脂饲料对低盐度下青蟹能量代谢的积极作用促进了渗透压调节。具体而言，在低盐度下投喂高脂饲料的螃蟹中，观察到血淋巴渗透压和无机离子含量显著更高，鳃中的渗透压调节酶活性以及NaK - ATPase的基因和蛋白质表达水平也更高（P < 0.05）。总之，高膳食脂质水平改善了能量供应，促进了线粒体生物发生，从而增加了用于青蟹渗透压调节的ATP供应。本研究还说明了膳食脂质营养补充对青蟹低盐度适应的重要性。
