The MicroRNAs and their targets in the channel catfish (Ictalurus punctatus).

MicroRNAs (miRNAs) are small, non-coding and negative regulatory RNAs about 22 nucleotides. They are mostly conserved among the organisms and this conservation makes them a good source for the identification of novel miRNAs by computational genomic homology. The miRNA repertoire of the major aquaculture species, channel catfish (Ictalurus punctatus), is unknown. This study is focused on computational search for novel miRNA homologs and their targets along with their characterization in channel catfish. Total 60 novel precursor miRNAs having 73 mature sequences belong to 45 families in channel catfish were identified and characterized. They belong to the miRNA families; ipu-let-7, miR-7, 10, 16, 24, 29, 32, 93, 99, 101, 105, 126, 127, 133, 135, 141, 142, 143, 144 145, 148, 150, 152, 153, 203, 210, 214, 221, 223, 293, 429, 430, 466, 682, 731, 737, 1388, 1594, 1642, 1701, 1782, 1814, 2145, 2182 and 3074 are reported for the first time in channel catfish. All the 73 mature miRNAs are observed in the stem portion of the stable minimum free energy stem-loop structures. Total 341 proteins targeted by the novel channel catfish miRNAs were also identified. They are involved in immune-related (32 %), signaling (15 %), transcription factors (15 %), metabolism (12 %), transportation (8 %), growth & development (5 %), structural (5 %) and others (8 %) proteins.