Abstract Leptin is an important energy homeostasis hormone in mammals. However, the role of leptin in energy balance of fish remains controversial. In this study, we characterized Yangtze sturgeon (Acipenser dabryanus) leptin (Adleptin) with a full-length 507 bp coding sequence (CDS) encoding 168 amino acids (aa) and we used phylogenetic analysis to identify it as leptin A. The tissue expression profiles suggested that Adleptin is widely expressed in various types of tissues, mainly in the liver. Moreover, the Adleptin level was detected during several important nutritional states. The Adleptin mRNA levels significantly increased in the liver after feeding while the levels were dramatically decreased during 10 days of fasting and increased upon refeeding. In comparison to the Tubificidae group, the Adleptin level in the formulated feed group was significantly lower on the 2nd and 5th days; after 2nd day, the level began to increase until it was significantly increased on the 8th day. These results indicate that leptin is an endocrine indicator of nutritional state in Yangtze sturgeon. This indicator can be used to monitor whether artificial nutrient conditions meet the nutritional requirements of Yangtze sturgeon and aid in developing and optimizing protection strategies for this species.

中文翻译：

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极度濒危长江鲟（Acipenser dabryanus）瘦素的特征、系统发育和对不同营养状态的反应

摘要 瘦素是哺乳动物体内一种重要的能量稳态激素。然而，瘦素在鱼类能量平衡中的作用仍存在争议。在这项研究中，我们用全长 507 bp 编码序列 (CDS) 编码 168 个氨基酸 (aa) 来表征扬子鲟 (Acipenser dabryanus) 瘦素 (Adleptin)，并使用系统发育分析将其鉴定为瘦素 A。 组织表达配置文件表明，Adleptin 在各种类型的组织中广泛表达，主要在肝脏中。此外，在几个重要的营养状态期间检测到 Adleptin 水平。喂食后肝脏中的 Adleptin mRNA 水平显着增加，而在禁食 10 天期间该水平显着降低，并在重新喂食后增加。与 Tubificidae 组相比，配合饲料组的Adleptin水平在第2天和第5天显着降低；第2天后，水平开始增加，直到第8天显着增加。这些结果表明瘦素是扬子鲟营养状态的内分泌指标。该指标可用于监测人工营养条件是否满足长江鲟的营养需求，并有助于制定和优化对该物种的保护策略。