The diverse color patterns of cichlid fishes play an important role in mate choice and speciation. Here we develop the Nile tilapia (Oreochromis niloticus) as a model system for studying the developmental genetics of cichlid color patterns. We identified 4 types of pigment cells: melanophores, xanthophores, iridophores and erythrophores, and characterized their first appearance in wild-type fish. We mutated 25 genes involved in melanogenesis, pteridine metabolism, and the carotenoid absorption and cleavage pathways. Among the 25 mutated genes, 13 genes had a phenotype in both the F0 and F2 generations. None of F1 heterozygotes had phenotype. By comparing the color pattern of our mutants with that of red tilapia (Oreochromis spp), a natural mutant produced during hybridization of tilapia species, we found that the pigmentation of the body and eye is controlled by different genes. Previously studied genes like mitf, kita/kitlga, pmel, tyrb, hps4, gch2, csf1ra, pax7b, and bco2b were proved to be of great significance for color patterning in tilapia. Our results suggested that tilapia, a fish with 4 types of pigment cells and a vertically barred wild-type color pattern, together with various natural and artificially induced color gene mutants, can serve as an excellent model system for study color patterning in vertebrates.

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尼罗罗非鱼：研究硬骨鱼颜色模式的模型

慈鲷鱼的多样化颜色模式在配偶选择和物种形成中起着重要作用。在这里，我们开发了尼罗罗非鱼 (Oreochromis niloticus) 作为研究慈鲷颜色模式发育遗传学的模型系统。我们确定了 4 种类型的色素细胞：黑素细胞、黄素细胞、虹彩细胞和红细胞，并表征了它们在野生型鱼类中的首次出现。我们突变了 25 个与黑素生成、蝶啶代谢以及类胡萝卜素吸收和切割途径相关的基因。在25个突变基因中，13个基因在F0和F2代都有表型。F1 杂合子没有表型。通过将我们的突变体的颜色模式与罗非鱼物种杂交过程中产生的天然突变体红罗非鱼（Oreochromis spp）的颜色模式进行比较，我们发现身体和眼睛的色素沉着是由不同的基因控制的。先前研究的基因如 mitf、kita/kitlga、pmel、tyrb、hps4、gch2、csf1ra、pax7b 和 bco2b 被证明对罗非鱼的颜色图案具有重要意义。我们的研究结果表明，罗非鱼是一种具有 4 种色素细胞和垂直条纹的野生型颜色图案的鱼，以及各种天然和人工诱导的颜色基因突变体，可以作为研究脊椎动物颜色图案的优秀模型系统。