Gunaratne et al. BMC Genomics 2011, 12:277 http://www.biomedcentral.com/1471-2164/12/277 Page 6 of 14 Figure 2 The genome locus for tgu-mir-2954 produces three different miRNAs. A. Alignments via the UCSC Genome Browser of the three detected miRNAs to the intron of the zebra finch XPA gene. B. Hairpin precursors for the three miRNAs. C. Northern blot analysis using an RNA probe complementary to novel miRNA tgu-miR-2954-3p. profile of miRNAs in parts of the songbird brain respon- sible for auditory perception, integration and memory. The song-regulated population includes both known (conserved) and novel miRNAs. We highlight one sex- linked song-responsive miRNA and identify mRNAs that are potential targets of its action during song expo- sure. Thus miRNAs may have roles in the information processing functions of the brain, in addition to their roles in brain development and evolution. To demonstrate this, we first catalogued the miRNAs expressed in the adult zebra finch auditory forebrain. We used massively parallel Illumina sequencing of small RNAs to perform this cataloguing efficiently. In addition to known conserved miRNAs, our analysis identified 48 small RNA sequences that meet the structural criteria for miRNAs but had not been described in miRBase in any organism at the time of our analysis. Fourteen of these are detected in the chicken or human genome