Comparative transcriptome and histological analyses provide insights into the skin pigmentation in Minxian black fur sheep (Ovis aries)

Abstract

Background Minxian black fur (MBF) sheep are found in the northwestern parts of China. These sheep have developed several special traits. Skin color is a phenotype subject to strong natural selection and diverse skin colors are likely a consequence of differences in gene regulation. Methods Skin structure, color differences, and gene expression (determined by RNA sequencing) were evaluated the Minxian black fur and Small-tail Han sheep (n = 3 each group), which are both native Chinese sheep breeds. Results Small-tail Han sheep have a thicker skin and dermis than the Minxian black fur sheep (P < 0.01); however, the quantity of melanin granules is greater (P < 0.01) in Minxian black fur sheep with a more extensive distribution in skin tissue and hair follicles. One hundred thirty-three differentially expressed genes were significantly associated with 37 ontological terms and two critical KEGG pathways for pigmentation (“tyrosine metabolism” and “melanogenesis” pathways). Important genes from those pathways with known involvement in pigmentation included OCA2 melanosomal transmembrane protein (OCA2), dopachrome tautomerase (DCT), tyrosinase (TYR) and tyrosinase related protein (TYRP1), melanocortin 1 receptor (MC1R), and premelanosome protein (PMEL). The results from our histological and transcriptome analyses will form a foundation for additional investigation into the genetic basis and regulation of pigmentation in these sheep breeds.

m 6 A mRNA Methylation Analysis Provides Novel Insights into Pigmentation in Sheep Skin

“…KEGG analysis showed that DEGs were significantly enriched in tyrosine metabolism (4 DEGs), melanogenesis (4 DEGs), neuroactive ligand–receptor interaction (6 DEGs). The result is similar to the previous study [ 41 , 42 ]. Meanwhile, GO terms of m 6 A modified genes also involved in pigmentation, such as regulation of synaptic transmission, dopaminergic, melanosome assembly, regulation of dopamine metabolic process, melanosome organization, negative regulation of kinase activity and melanosome membrane, which is similar to GO enrichment of DEGs.…”

Identification of Polymorphisms in the <i>HERC2</i>-<i>OCA2</i> Gene Locus and their Association with Feather Color in Quail

“…The expression of OCA2 can regulate eumelanin biosynthesis in several tissues. For example, OCA2 mRNA expression is higher in black Minxian black fur sheep than in white small-tail Han sheep ( Shi et al , 2021 ), which is consistent with our finding OCA2 mRNA exhibits higher expression in the skin tissue of Korean quail than in the skin of Beijing white quail. These phenomena primarily occur because the cells involved in pigmentation are the same in different tissues, and the pigment synthesis pathways and regulation mechanisms are similar in different breeds ( Lin et al , 2013 ).…”

Identifying Candidate Genes for Litter Size and Three Morphological Traits in Youzhou Dark Goats Based on Genome-Wide SNP Markers

“…Additionally, it was demonstrated that human skin pigmentation is complex, the genetic architecture varies by latitude and known pigmentation loci explain only a small fraction of the variance [ 36 ]. Likewise, similar outcomes have been reported in investigations in sheep and cattle [ 37 , 38 ]. Although some progress has been made in the elucidation of the genetic basis of skin pigmentation in humans [ 39 ], chickens [ 40 , 41 ], cattle [ 42 ], sheep [ 43 ] and so on, the genetics of skin colour are currently less understood than those of hair colour.…”