Cloning, identification, and expression analysis at the stage of gonadal sex differentiation of chicken miR-363 and 363*.

miRNAs (microRNAs) are small, functional, non-coding RNAs and have been proved to implicate in regulation of diverse biological processes ranging from cell differentiation to organism development. With the purpose of exploring the roles of miRNAs on chicken embryo sexual determination and gonadal differentiation, we cloned and identified the stem-loop precursor structure (GenBank accession no. GU597370) of chicken miR-363 and 363* followed by studying their temporal and spatial expression patterns in chicken embryo at the stage of E3.5-6.5 d (embryonic days 3.5-6.5) by semi-quantitative RT-PCR and WISH (whole-mount in situ hybridization) in this study. The results showed that miR-363* located in cloned sequence of unknown segment in chicken genome, and flanking sequence of miR-363 and 363* according to the structural features of miRNAs precursor. Significantly differential expression (P < 0.05) of gga-miR-363 between female and male chicken embryonic gonads was found at E4.5 and 6.5 d, but the differential expression of gga-miR-363* from E3.5 to 6.5 d between both sexes fell short of significant level. The results of WISH indicated that expression signals of gga-miR-363 mainly appeared at limb bud, notochord, ectoderm, brain in E4.5 d chicken embryo, and urogenital systems (UGSs) at E6.5 d, and the expression level of E6.5 d was higher in the female than that in the male. It can be speculated that gga-miR-363 would involve in the gonadal development and gga-miR-363* might have transient regulatory functions during the early stages of chicken embryo development.