Identification of male-biased gene: parvalbumin in song control nuclei of the Bengalese finch.

Sex differences in song nuclei are evident across songbirds. To explore candidate genes involving in the sexual dimorphism of song nuclei, the present study used suppression subtraction hybridization to identify male-biased genes in the Bengalese finch (Lonchura striata). From 199 clones with an inserted sequence, we obtained a gene (parvalbumin, PV) coding a calcium-binding protein, which showed, through semi-quantitative PCR, obviously male-biased expression. In situ hybridization and immunohistochemistry indicated that PV was sexually distributed in most of the studied song nuclei, including in the high vocal center (HVC), the robust nucleus of the arcopallium (RA), Area X, and the lateral magnocellular nucleus of the anterior nidopallium (lMAN) for three studied age groups, namely, posthatching day (PD) 15, 45, and adult. The total number of PV mRNA or protein cells was significantly larger in males in the HVC, RA, and Area X for PD45 and adult. Considering that calcium-binding proteins have reported effects on the maturation of some brain areas, and on the sexual differentiation of mammalian brain areas by affecting cell survival rates, our study suggests that PV may be involved in the functional maturation of neurons in song nuclei or the sexual differentiation of song system.