ABSTRACT The effects of cadmium concentration (0, 2.5 and 5 mg L−1) on melanocyte-stimulating hormone (MSH), melanophore index (MI), and melanophore number (MN), as well as a microscopic examination of scale melanocytes in tilapia (Oreochromis niloticus Linnaeus, 1757) was evaluated at different salinity levels (0, 5 and 15 ppt). The levels of MSH, MI, and MN were lower in Cd-exposed fish than in control fish (not exposed to Cd) at salinity level of 0 and 5 ppt. In ppt, however these levels of MSH, MI and MN in control and Cd-exposed fish were not significantly different. In the media without Cd, the levels of MSH, MI and MN were not significantly different at all salinities. The morphological changes of melanophores were higher in Cd-exposed fish than in control fish at salinity 0 and 5 ppt, respectively. These morphological changes were not significantly different in the control fish at all salinities as well as in fish exposed to 0–5 mg L−1 Cd at salinity of 15 ppt. This study therefore demonstrates that the toxic effect of Cd on MSH levels and melanophore morphology decreased with increasing salinity. Further, due to the sensitivity of chromatophores to Cd, melanophore morphology is proposed as a biomarker of Cd exposure in aquatic ecosystems.

中文翻译：

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镉对不同盐度条件下慈鲷鱼 Oreochromis niloticus 血浆促黑素细胞激素和黑色素细胞形态变化的影响

摘要 镉浓度（0、2.5 和 5 mg L-1）对促黑素细胞激素 (MSH)、黑素细胞指数 (MI) 和黑素细胞数量 (MN) 的影响，以及对罗非鱼鳞状黑素细胞的显微镜检查（Oreochromis niloticus Linnaeus，1757）在不同的盐度水平（0、5 和 15 ppt）下进行了评估。在 0 和 5 ppt 的盐度水​​平下，暴露于 Cd 的鱼的 MSH、MI 和 MN 水平低于对照鱼（未暴露于 Cd）。然而，在 ppt 中，对照和 Cd 暴露的鱼中 MSH、MI 和 MN 的这些水平没有显着差异。在不含 Cd 的培养基中，MSH、MI 和 MN 的水平在所有盐度下均无显着差异。在盐度分别为 0 和 5 ppt 时，暴露于 Cd 的鱼中黑色素细胞的形态变化高于对照鱼。这些形态变化在所有盐度下的对照鱼以及在 15 ppt 盐度下暴露于 0-5 mg L-1 Cd 的鱼中没有显着差异。因此，该研究表明，Cd 对 MSH 水平和黑色素细胞形态的毒性作用随着盐度的增加而降低。此外，由于色素细胞对 Cd 的敏感性，黑色素细胞形态被提议作为水生生态系统中 Cd 暴露的生物标志物。