Convergent musk biosynthesis across host and microbiota in musk deer and muskrat.

Mammalian scent glands mediate species-specific chemical communication, yet the mechanistic basis for convergent musk production remain incompletely understood. Forest musk deer and muskrat have independently evolved specialized musk-secreting glands, representing a striking case of convergent evolution. Through an integrated multi-omics approach, this study identified cyclopentadecanone as a shared key metabolic precursor in musk from both forest musk deer and muskrat, although downstream metabolite profiles diverged between the two lineages. Single-cell RNA sequencing revealed that these specialized apocrine glands possessed unique secretory architecture and exhibited transcriptional profiles associated with periodic musk production, distinct from those in conventional apocrine glands. Convergent features were evident at the cellular level, where acinar, ductal, and basal epithelial subtypes showed parallel molecular signatures across both taxa. Notably, acinar cells in both species expressed common genes involved in fatty acid and glycerolipid metabolism (e.g., ACSBG1, HSD17B12, HACD2, and HADHA), suggesting a conserved molecular framework for musk precursor biosynthesis. Metagenomic analysis of musk samples further revealed parallel microbial community structures dominated by Corynebacterium and enriched in lipid metabolic pathways. These findings suggest multi-level convergence in musk biosynthesis, from molecular pathways to microbial communities, providing novel insights into mammalian chemical signaling and artificial musk production.