Actinopterygian fishes harbor at least eight distinct pigment cell types, leading to a fascinating diversity of colors. Among this diversity, the cellular origin of the white color appears to be linked to several pigment cell types such as iridophores or leucophores. We used the clownfish Amphiprion ocellaris, which has a color pattern consisting of white bars over a darker body, to characterize the pigment cells that underlie the white hue. We observe by electron microscopy that cells in white bars are similar to iridophores. In addition, the transcriptomic signature of clownfish white bars exhibits similarities with that of zebrafish iridophores. We further show by pharmacological treatments that these cells are necessary for the white color. Among the top differentially expressed genes in white skin, we identified several genes (fhl2a, fhl2b, saiyan, gpnmb, and apoD1a) and show that three of them are expressed in iridophores. Finally, we show by CRISPR/Cas9 mutagenesis that these genes are critical for iridophore development in zebrafish. Our analyses provide clues to the genomic underpinning of color diversity and allow identification of new iridophore genes in fish.

中文翻译：

---

发育和比较转录组学鉴定虹彩载体对小丑鱼白色禁止的贡献。

放线翅目鱼类至少含有八种不同的色素细胞类型，从而导致令人着迷的颜色多样性。在这种多样性中，白色的细胞起源似乎与几种色素细胞类型有关，例如虹膜或隐色体。我们使用了小丑鱼Amphiprion ocellaris，该鱼的颜色图案由深色主体上的白色条组成，以表征构成白色色调的色素细胞。我们通过电子显微镜观察到，白色条形中的细胞类似于虹膜。此外，小丑鱼白色条的转录组特征与斑马鱼虹膜的相似。我们通过药理学处理进一步表明这些细胞对于白色是必需的。在白皮肤中最常见的差异表达基因中，我们鉴定了几个基因（fhl2a，fhl2b，saiyan，gpnmb和apoD1a），并显示其中的三个在虹彩团中表达。最后，我们通过CRISPR / Cas9诱变表明，这些基因对于斑马鱼虹吸体的发育至关重要。我们的分析为颜色多样性的基因组基础提供了线索，并允许鉴定鱼类中新的虹吸虫基因。