Identification and characterization of microRNAs from the bovine adipose tissue and mammary gland.

We report the identification of bovine miRNAs by cloning small RNAs from adipose tissue and the mammary gland. Fifty-nine distinct miRNAs were identified, five of them were not homologous to known mammalian miRNAs, and many of them had 3' and/or 5' end variants. Ribonuclease protection assays indicated that miR-23a and miR-24, whose genes are closely located on the same chromosome, were co-expressed in different tissues. The assays also suggested a role for several miRNAs in the mammary gland and a role for miR-133, a previously known skeletal and cardiac muscle-specific miRNA, in the rumen, an organ unique to the ruminant.