Liang Guangyuan, Yao Jiawen, Wu Jinzhi, Liu Xiayue, Wen Zilong, Liu Hao, Lu Baoyue, Wang Chenxu, Liu Xingyong, Wang Deshou
Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, School of Life Sciences, Southwest University, Chongqing, China.
J Hered. 2025 Jul 21;116(4):466-478. doi: 10.1093/jhered/esaf017.
There has been controversy over whether the chromogenic substances of xanthophores and erythrophores are pteridines or carotenoids in fish. In this study, we first extracted and quantified carotenoids and pteridines from erythrophores and xanthophores in tilapia, respectively. The results showed that the carotenoids and pteridines in erythrophores were significantly higher than those of xanthophores, and the carotenoids were significantly higher than the pteridines in both types of cells. Then, we established homozygous mutant lines of the key genes for pteridine synthesis (xdh) and carotenoid metabolism (plin6) in Nile tilapia. Compared with the wild type (WT), there were no significant changes in the body color of xdh-/-, while the pigmentation, fluorescence intensity, and size of both xanthophores and erythrophores were significantly reduced in plin6-/-. The pteridines were significantly decreased in xdh-/-, but not in plin6-/-, while the carotenoids were significantly decreased in plin6-/-, but not in xdh-/-. To confirm these results, we further established homozygous mutant lines for another two key genes involved in pteridine synthesis (gch2) and carotenoid absorption (scarb1). Consistently, no significant body color changes were observed in gch2-/-, while no pigmented xanthophores and erythrophores were observed in scarb1-/-. The pteridines were significantly reduced in gch2-/-, but not in scarb1-/-, while almost no carotenoids were detected in scarb1-/-, but carotenoids remained unchanged in gch2-/- compared with WT. Taken together, these results, combined with existing findings in cyprinid fish, demonstrate that the color of xanthophores and erythrophores is determined by carotenoids rather than pteridines in fish.
在鱼类中，关于黄色素细胞和红色素细胞的发色物质是蝶啶还是类胡萝卜素一直存在争议。在本研究中，我们首先分别从罗非鱼的红色素细胞和黄色素细胞中提取并定量了类胡萝卜素和蝶啶。结果表明，红色素细胞中的类胡萝卜素和蝶啶显著高于黄色素细胞，且在这两种细胞类型中，类胡萝卜素均显著高于蝶啶。然后，我们建立了尼罗罗非鱼中蝶啶合成关键基因（xdh）和类胡萝卜素代谢关键基因（plin6）的纯合突变系。与野生型（WT）相比，xdh-/-的体色没有显著变化，而plin6-/-中黄色素细胞和红色素细胞的色素沉着、荧光强度和大小均显著降低。xdh-/-中的蝶啶显著减少，但plin6-/-中没有；而plin6-/-中的类胡萝卜素显著减少，但xdh-/-中没有。为了证实这些结果，我们进一步建立了另外两个参与蝶啶合成（gch2）和类胡萝卜素吸收（scarb1）的关键基因的纯合突变系。一致地，gch2-/-中未观察到显著的体色变化，而scarb1-/-中未观察到有色素沉着的黄色素细胞和红色素细胞。gch2-/-中的蝶啶显著减少，但scarb1-/-中没有；而scarb1-/-中几乎未检测到类胡萝卜素，与WT相比，gch2-/-中的类胡萝卜素保持不变。综上所述，这些结果与鲤科鱼类的现有研究结果相结合，表明在鱼类中，黄色素细胞和红色素细胞的颜色是由类胡萝卜素而非蝶啶决定的。
