Expression analysis of miR-2954. (A) Northern blot analysis shows that miR-2954 was expressed in brain and liver tissues of male zebra finches, but was not detectable in mouse or human tissues. (B) Northern blot shows expression of miR-2954 and miR-9 in the brain tissues of female and male zebra finches. (C) Sex-biased expression of miR-2954 in the brain, heart, liver, muscle, ovary, and testis of male and female zebra finches validated by qRT-PCR. (D) Expression ratios of Z chromosome-encoded miRNAs between male and female zebra finch tissues based on sequence reads. Note, miR-2973, another Z chromosome-encoded miRNA, was not included here because its total combined reads were < 100.