Cholesterol, as an indispensable nutrient, regulates molting and growth in crustacean. As crustaceans are unable to biosynthesize cholesterol de novo, it is central to understand how dietary cholesterol affects molting in crustaceans. An 8-week feeding trial was conducted to evaluate the effects of dietary cholesterol level (0.12%, 0.43%, 0.79%, 1.00%, 1.30% and 2.50%) on growth, cholesterol metabolism and expression of genes related to lipid and ecdysone metabolism in female swimming crabs (Portunus trituberculatus). A total of 192 crabs (1.41 ± 0.05 g) were randomly distributed into 192 aquaria. Each treatment had 4 replicates with each replicate containing 8 crabs. Crabs fed the 1.00% cholesterol diet showed best growth performance, and thus based on percent weight gain, the optimal dietary cholesterol requirement was calculated at 1.01%. Tissue cholesterol concentrations were positively correlated with dietary cholesterol level. The contents of functional fatty acids in hepatopancreas significantly increased as dietary cholesterol increased from 0.12% to 2.50% (P < 0.05). The expression levels of genes related to lipogenesis pathway, lipid catabolism and fatty acid oxidation were significantly down-regulated with increased dietary cholesterol level (P < 0.05). The highest expression levels of cholesterol transport genes, low-density lipoprotein receptor (ldlr) and low-density lipoprotein receptor-related protein 2 (lrp2) occurred in crabs fed the 1.30% cholesterol diet. Moreover, hormones related to molting such as crustacean hyperglycemic hormone (CHH), methyl farnesoate (MF), molt-inhibiting hormone (MIH), and ecdysone in hemolymph were significantly influenced by dietary cholesterol level (P < 0.05). The highest expression levels of ecdysone receptor (ecr) and chitinase 1 (chi1) in eyestalk and hepatopancreas were found in crabs fed the diet containing 1.00% cholesterol (P < 0.05). In conclusion, the optimal dietary level was beneficial to functional fatty acid accumulation, regulated lipid metabolism, promoted the ecdysone signalling pathway by improving the cholesterol transport, and improved the molting rate and growth of swimming crabs.

胆固醇作为一种不可缺少的营养物质，调节着甲壳类动物的蜕皮和生长。由于甲壳类动物无法从头生物合成胆固醇，因此了解膳食胆固醇如何影响甲壳类动物的蜕皮至关重要。进行了为期 8 周的喂养试验，以评估膳食胆固醇水平（0.12%、0.43%、0.79%、1.00%、1.30% 和 2.50%）对生长、胆固醇代谢以及与脂质和蜕皮激素代谢相关的基因表达的影响在雌性游泳蟹 ( Portunus trituberculatus）。共有 192 只螃蟹 (1.41 ± 0.05 g) 被随机分配到 192 个水族箱中。每个处理有4个重复，每个重复包含8只螃蟹。喂食 1.00% 胆固醇饮食的螃蟹表现出最佳生长性能，因此根据体重增加百分比，最佳饮食胆固醇需求量计算为 1.01%。组织胆固醇浓度与膳食胆固醇水平呈正相关。随着膳食胆固醇从0.12%增加到2.50%，肝胰腺中功能性脂肪酸含量显着升高（P  < 0.05）。脂肪生成通路、脂质分解代谢和脂肪酸氧化相关基因的表达水平随着膳食胆固醇水平的升高而显着下调（P < 0.05)。胆固醇转运基因、低密度脂蛋白受体 ( ldlr ) 和低密度脂蛋白受体相关蛋白 2 ( lrp2 ) 的最高表达水平出现在喂食 1.30% 胆固醇饮食的螃蟹中。此外，与蜕皮有关的激素如甲壳类动物高血糖激素（CHH）、法尼酸甲酯（MF）、蜕皮抑制激素（MIH）和血淋巴中的蜕皮激素受膳食胆固醇水平的影响显着（P  < 0.05）。在喂食含1.00 % 胆固醇( P < 0.05)。综上所述，最佳日粮水平有利于功能性脂肪酸积累，调节脂质代谢，通过改善胆固醇转运促进蜕皮激素信号通路，提高游泳蟹的蜕皮率和生长速度。