The budgerigar (Melopsittacus undulatus) is one of the most widely studied parrot
species, serving as an excellent animal model for behavior and neuroscience research.
Until recently, it was unknown how sexual differences in the behavior, physiol-
ogy, and development of organisms are regulated by differential gene expression.
MicroRNAs (miRNAs) are endogenous short non-coding RNA molecules that can
post-transcriptionally regulate gene expression and play a critical role in gonadal
differentiation as well as early development of animals. However, very little is known
about the role gonadal miRNAs play in the early development of birds. Research on
the sex-biased expression of miRNAs in avian gonads are limited, and little is known
about M. undulatus. In the current study, we sequenced two small non-coding RNA
libraries made from the gonads of adult male and female budgerigars using Illumina
paired-end sequencing technology. We obtained 254 known and 141 novel miRNAs,
and randomly validated five miRNAs. Of these, three miRNAs were differentially
expressed miRNAs and 18 miRNAs involved in sexual differentiation as determined
by functional analysis with GO annotation and KEGG pathway analysis. In conclusion,
this work is the first report of sex-biased miRNAs expression in the budgerigar, and
provides additional sequences to the avian miRNAome database which will foster
further functional genomic research.