# Single-Nucleus Transcriptional Profiling Revealed Cell Diversity and Albino Mutation Mechanism in the Skin of Channa argus

## TL;DR

This study uses single-nucleus RNA sequencing to explore skin cell diversity and the albinism mechanism in snakehead fish.

## Contribution

The study provides a single-cell transcriptional atlas of C. argus skin and identifies key genes linked to albinism.

## Key findings

- Albino C. argus skin contains melanocytes with fewer melanin granules and iridophores with increased chromogenic substances.
- Genes like scarb1, pnp, and alk are significantly associated with albinism in C. argus skin cells.
- Weighted gene co-expression analysis links scarb1 to melanocytes and alk/pnp to iridophores in albinism.

## Abstract

Body color is the most prominent phenotypic trait in animals. To investigate the molecular regulatory mechanisms underlying skin pigmentation and body color in Channa argus, single-nucleus RNA sequencing technology was employed to analyze cell diversity and functional changes in the skin of normal and albino C. argus. Three pigment-related cell types, seven immune-related cell types, and nine other skin-related structural and functional cell types were identified. The skin of albino C. argus, which appears white to the naked eye, contains numerous melanocytes and iridophores with reflective silver properties. Compared to normal C. argus, melanocytes in albino individuals contained fewer melanin granules, while iridophores exhibited increased chromogenic substances. Melanocyte-specific genes—kitlg, myo5a, and scarb1—were significantly downregulated in albino melanocytes (p < 0.05). Conversely, iridophore-specific genes alk, pnp, and gpnmb were significantly upregulated in albino skin, whereas mlph was significantly downregulated (p < 0.05). Weighted gene co-expression network analysis revealed that scarb1 was associated with the melanocyte module, alk was identified as a core gene, and pnp was linked to the iridophore module. Functionally, scarb1 is involved in pigment transport, pnp in purine synthesis, and alk is essential for iridophore development. Therefore, scarb1, pnp, and alk may be correlated to albinism in C. argus. Overall, this study constructed a single-cell transcriptional atlas of C. argus skin, providing valuable reference data for further research into the regulatory mechanisms governing body color formation and maintenance in this species.