Gallus gallus gallus. Gallus gallus gallus

Puberty onset is an complicated physiological process that comprises many genes and regulatory factors. The observations in model organisms and mammals including humans have shown a potential link between miRNAs and puberty onset. To determine whether miRNAs play roles in this process in the chicken (Gallus gallus), the Solexa deep sequencing was performed to analyze the profiles of miRNA expression in the hypothalamus of hens from two different pubertal stages, before puberty onset (BPO) and after puberty onset (APO). 374 conserved and 46 novel miRNAs were identified as hypothalamus-expressed miRNAs in the chicken. 144 conserved miRNAs were showed to be differentially expressed (reads > 10, P 4.0, P < 0.01). Of these genes, 7 putative circadian clock genes, Per2, Bmal1/2, Clock, Cry1/2, and Star were found to be targeted multiple times by the miRNAs. qRT-PCR revealed the basic transcription levels of these clock genes were much higher (P < 0.01) in APO than in BPO. Further functional analysis suggested that these 15 miRNAs play important roles in transcriptional regulation and signal transduction during puberty onset. The results provide new insights into miRNAs functions in chicken puberty onset. Considering the characteristics of miRNA functional conservation, the results will contribute to the research in humans.