Molecular Basis of Color Variation in Taiwanese Loach Revealed by Early Developmental Transcriptome Analysis.

Area of Science:

• Aquaculture
• Developmental Biology
• Genomics

Background:

• Taiwanese loach (Paramisgurnus dabryanus) is crucial for East Asian aquaculture, with body color impacting market value.
• A golden-red mutant (MR) discovered in wild-type (WT) populations shows reduced melanophores and sequential xanthophore/erythrophore development.
• Body color variation in MR likely stems from gene regulatory network alterations during early embryogenesis.

Purpose of the Study:

• Compare transcriptomes of WT and MR Taiwanese loach during early development.
• Identify key regulatory pathways for red body color formation.
• Investigate the classical melanin synthesis pathway and provide a basis for selective breeding.

Main Methods:

• High-throughput transcriptome sequencing across eight developmental stages (0-43 hpf).
• Differential expression, time-series trend, and KEGG pathway enrichment analyses.
• Real-time PCR for transcriptomic data validation.

Main Results:

• MR exhibited significant downregulation of the core transcription factor mitfa, leading to impaired melanogenesis.
• Pathways for oxidative stress, unsaturated fatty acid biosynthesis, and thyroid hormone synthesis were significantly altered in MR embryos.
• WT showed opposite trends in these pathways; qRT-PCR confirmed transcriptome data.

Conclusions:

• Downregulation of mitfa initiates red body color variation in Taiwanese loach by affecting melanin synthesis.
• A coordinated network involving oxidative stress, immune inflammation, and thyroid hormone signaling is activated.
• This study elucidates the mitfa-mediated mechanism for transitioning to carotenoid/pteridine-based coloration in fish, aiding molecular breeding.