Abstract
BackgroundRecent evidence suggests that some sex differences in brain and behavior might result from direct genetic effects, and not solely the result of the organizational effects of steroid hormones. The present study examined the potential role for sex-biased gene expression during development of sexually dimorphic singing behavior and associated song nuclei in juvenile zebra finches.ResultsA microarray screen revealed more than 2400 putative genes (with a false discovery rate less than 0.05) exhibiting sex differences in the telencephalon of developing zebra finches. Increased expression in males was confirmed in 12 of 20 by qPCR using cDNA from the whole telencephalon; all of these appeared to be located on the Z sex chromosome. Six of the genes also showed increased expression in one or more of the song control nuclei of males at post-hatching day 25. Although the function of half of the genes is presently unknown, we have identified three as: 17-beta-hydroxysteroid dehydrogenase type IV, methylcrotonyl-CoA carboxylase, and sorting nexin 2.ConclusionThe data suggest potential influences of these genes in song learning and/or masculinization of song system morphology, both of which are occurring at this developmental stage.
Highlights
Recent evidence suggests that some sex differences in brain and behavior might result from direct genetic effects, and not solely the result of the organizational effects of steroid hormones
We found robust sex differences in gene expression in the developing zebra finch brain, and identified six genes that are both sex-linked and differentially expressed in the male compared to female song system
The present study identified more than 2400 putative genes with sex differences in expression across multiple ages in zebra finches; of a subset analyzed with quantitative polymerase chain reaction (qPCR), 12 mRNAs (2 of them representing the same gene) with substantially greater expression in males were validated using qPCR
Summary
Recent evidence suggests that some sex differences in brain and behavior might result from direct genetic effects, and not solely the result of the organizational effects of steroid hormones. The present study examined the potential role for sex-biased gene expression during development of sexually dimorphic singing behavior and associated song nuclei in juvenile zebra finches. Dimorphic behaviors including types of displays, such as vocal or sexual behaviors, occur across diverse species. Elegant work exists on the development of song and the brain regions associated with it in zebra finches. Most brain regions that control song are sexually dimorphic in adults [5]. They include the lateral magnocellular nucleus of the anterior nidopallium (lMAN), area X in the (page number not for citation purposes)
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