Screening and expression analysis of genes related to skin coloration in pearlscale angelfish (Centropyge vrolikii)

The skin coloration is one of the key characteristics of fish morphological diversity; understanding the molecular regulation mechanism of fish skin coloration has attracted a mounting number of attention and is also an important prerequisite for the future research on fish skin coloration genetics and skin coloration improvement breeding of fish. Pearlscale angelfish (Centropyge vrolikii) is a unique marine ornamental fish with tremendous market potential and is well favored by consumers in China, which has a wide variety of colorations and shapes. In this study, the distribution of pigment cells in the fins and scales was observed, and the pigment cells were mainly composed of melanocytes, xanthophore, iridophore, and erythrophore in C. vrolikii. The distribution of pigment cells in the tail scales is more concentrated than that in other parts. There are mainly melanocytes and yellow pigment cells in the anal fin, tail fin, and dorsal fin, and mainly xanthophore with a few melanocytes in the pectoral fin and abdominal fin. The tissues of the pectoral fin (PF), anal fin (AF), tail fin (TF), and eyeballs (EB) were sequenced by SOAPdenovo-Trans technology, the differentially expressed genes (DEGs) of skin coloration were screened, and the expression pattern of these genes in different tissues was analyzed. The results represented that a total of 159,213 all-unigene was assembled and gene annotation was carried out using COG, GO, KEGG, KOG, Pfam, Swissprot, eggNOG, and NR functional database. The Tyrp1, Slc45a2, Xdh, Mitf, Tyr, Hps5, Pomc, Pmel, and other genes related to the skin coloration were annotated. Through KEGG pathway enrichment analysis, it was found that tyrosine metabolism, MAPK, Wnt, and melanin production were involved in the regulation of skin coloration. At the same time, the DEGs related to melanin production (Mitf, Mc1r, Sox10, Tyr, Tyrp1, and Pomc) were screened to verify their expression in various tissues. The results also showed that Mitf and Tyr were highly expressed in eyeballs, Tyrp1 was highly expressed in skin, Sox10 and Pomc were highly expressed in the tail fin, and Mc1r was highly expressed in the heart and tail fin. The results suggested that these genes may play an important role in the process of skin coloration in C. vrolikii. This study will help to further understand the molecular regulatory mechanism of skin coloration and provide essential clues for accelerating skin coloration improvement in the future in C. vrolikii.

Automated summary

The distribution of pigment cells in the fins and scales of pearlscale angelfish was observed, and genes related to skin coloration were annotated and screened. The results indicated that melanocytes were more concentrated in the tail scales, melanocytes and yellow pigment cells were mainly present in the anal fin, tail fin, and dorsal fin, and xanthophore with a few melanocytes were mainly present in the pectoral fin and abdominal fin. Through KEGG pathway enrichment analysis, it was found that tyrosine metabolism, MAPK, Wnt, and melanin production were involved in the regulation of skin coloration in C. vrolikii.