Comparative Transcriptome and Gene-Editing Analyses Reveal the Molecular Mechanism of Albinism in the Taiwanese Loach

The Taiwanese loach (Paramisgurnus dabryanus ssp. Taiwanese), known for its nutritional and ornamental qualities, exhibits a rare form of albinism. Specifically, certain individuals display golden-pink eyes and a golden-red body color devoid of blotches, thereby attracting consumers. However, the principal genes regulating this phenotype remain unidentified. Consequently, this study conducted a transcriptome comparative analysis of the skin between wild-type (M) and mutant (N) Taiwanese loaches. A total of 6,152 differentially expressed genes (DEGs) were identified, comprising 2,467 down-regulated and 3,685 up-regulated DEGs in mutant individuals. Additionally, several pigmentation-related genes (mitf, wnt3, mc1r, wnt1, dct, tyrp1, and tyr) were identified. KEGG enrichment analysis of DEGs revealed pathways associated with melanin deposition, including the melanogenesis, tyrosine metabolism, and folate biosynthesis pathways. Eleven DEGs were randomly selected to validate RNA-seq results through qPCR. Furthermore, key genes (tyr, mc1r) were validated through gene knockout, accurately identifying the main gene responsible for color mutation in the Taiwanese loach. This study not only offers new insights into the molecular mechanism underlying abnormal body color in the Taiwanese loach but also demonstrates that gene knockout technology can rapidly produce a large quantity of golden-red loaches, significantly enhancing their economic value.