A Simple Method for <scp>RNA</scp> ‐Seq of Manually Isolated Chromatophores in <i>Oryzias</i> Fishes

RNA sequencing (RNA-seq) has become an essential tool for analyzing gene expression and exploring cell type-specific transcriptomes. However, sample preparation and quality control remain challenging, as current approaches typically rely on dissecting tissues containing mixed cell populations or using flow cytometry to isolate fluorescently labeled cells. Here we present a simple and reliable method for RNA-seq of chromatophores (pigment cells) by manually isolating cells based on their natural pigmentation. We analyzed four chromatophore types-melanophores, xanthophores, iridophores, and leucophores-in medaka (Oryzias latipes). Remarkably, as few as 100 cells per type yielded reasonably high-quality transcriptomes sufficient to identify differentially expressed genes (DEGs). Furthermore, this method was successfully applied to a non-model medaka species, O. woworae, which shares the same four chromatophore types. Our approach enables efficient, low-cost, and cross-species transcriptome analysis of chromatophores without requiring transgenic markers or flow cytometry.