Abstract：Previous Solexa sequencing analysis from miRNA in the hypothalamus of 1-day-old and 36-weeks Gushi chickens demonstrated that let-7a is one of the most abundant and differential expression miRNA during development of chicken(Gallus domesticus) hypothalamus. For a thorough knowledge of let-7a function, the let-7a expression profiles in 13 tissues in two stages of Gushi chicken were characterized by Real-time quantitative PCR. The results indicated that the let-7a was widely expressed in the detection tissue and the expression in hypothalamus from the Solexa sequencing was consistent with those from Real-time RT-PCR measures. Let-7a was varied among different tissues，with most abundant in the hypothalamus and kidney, low abundance in the lung and moderate expression in other tissues at 1-day-old chickens. Except for the lung, the let-7a expression was lower at the age of 36 weeks than that at 1 day. In addition, The total 107 target genes were predicted by two kinds of algorithm overlap with gene ontology(GO) and kyoto encyclopedia of genes and genomes(KEGG) analysis, the results showed that target genes were rich in the regulation biological processes, especially in the minerals and phosphorus metabolism regulation process and significantly existed in the regulatory pathway of focal adhesions, extracellular matrix receptor interaction, the mitogen-activated protein kinases(MAPK) signaling pathway (P<0.01). These results provide useful clues for further study of let-7a function.
