Identification and Characterization of microRNAs in Morphological Color Change of Polychromatic Midas Cichlids (Amphilophus citrinellus)

Abstract

As a representative genetic and economic trait, pigmentation has a strong impact on speciation and adaptation. However, information and reports on microRNAs (miRNAs) associated with pigmentation remain limited. The Midas cichlid fish, with three typical distinct stages of body color pattern, “black-gray-gold”, is an ideal model system for investigating pigmentation traits. In this study, miRNA libraries from scale tissues with the attached epidermis of Midas cichlids at three distinct stages of color transformation, black (B), transition (T), and gold (G), were sequenced using Illumina sequencing technology. In total, 53 (B vs. G), 88 (B vs. T), and 57 (T vs. G) miRNAs were differentially expressed between the respective groups. Target genes of the identified miRNAs were predicted, and the results showed that multiple target genes were related to pigmentation and pigment–cell differentiation. The miRNA–mRNA regulatory network suggests that miR-183-x and miR-133-x were predicted to be involved in regulating morphological color changes in Midas cichlids. The results advance our understanding of potential functions of miRNAs in skin pigment differentiation and early skin color fading of fishes.