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Sexual differentiation of the zebra finch song system: potential roles for sex chromosome genes.

Tomaszycki ML, Peabody C, Replogle K, Clayton DF, Tempelman RJ, Wade J - BMC Neurosci (2009)

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Psychology & Program in Neuroscience, Michigan State University, East Lansing, MI, USA. tomaszy1@msu.edu

ABSTRACT

Background: 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.

Results: A 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.

Conclusion: The 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.

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Related in: MedlinePlus

Darkfield images from in situ hybridization depicting sexually dimorphic mRNA expression for CK303566in the zebra finch song system at day 25 post-hatching. Arrows delineate borders of song regions. This gene showed the most extensive sex differences in expression. In lMAN (lateral magnocellular nucleus of the anterior nidopallium) males (A) show higher levels of mRNA expression (i.e. higher densities of silver grains) than do females (B). Similar differences were obtained in the portion of the medial striatum which contains area X in males (C), although area X is not morphologically distinct in females (D), and in RA (robust nucleus of the arcopallium, panels E = males, F = females). However, in HVC, no specific labeling was detected in either sex (panel G = male, panel H = female). Scale bar = 200 μm for lMAN and area X; 100 μm for HVC and RA.
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Figure 2: Darkfield images from in situ hybridization depicting sexually dimorphic mRNA expression for CK303566in the zebra finch song system at day 25 post-hatching. Arrows delineate borders of song regions. This gene showed the most extensive sex differences in expression. In lMAN (lateral magnocellular nucleus of the anterior nidopallium) males (A) show higher levels of mRNA expression (i.e. higher densities of silver grains) than do females (B). Similar differences were obtained in the portion of the medial striatum which contains area X in males (C), although area X is not morphologically distinct in females (D), and in RA (robust nucleus of the arcopallium, panels E = males, F = females). However, in HVC, no specific labeling was detected in either sex (panel G = male, panel H = female). Scale bar = 200 μm for lMAN and area X; 100 μm for HVC and RA.

Mentions: Specific expression of CK303566 was detected in lMAN, Area X and RA, but not HVC (Figure 2). The density of labeling was greater in males than females in all three areas (lMAN: t = 3.32, p = 0.008; Area X: t = 3.35, p = 0.007; RA: t = 3.89, p = 0.003; Table 3).


Sexual differentiation of the zebra finch song system: potential roles for sex chromosome genes.

Tomaszycki ML, Peabody C, Replogle K, Clayton DF, Tempelman RJ, Wade J - BMC Neurosci (2009)

Darkfield images from in situ hybridization depicting sexually dimorphic mRNA expression for CK303566in the zebra finch song system at day 25 post-hatching. Arrows delineate borders of song regions. This gene showed the most extensive sex differences in expression. In lMAN (lateral magnocellular nucleus of the anterior nidopallium) males (A) show higher levels of mRNA expression (i.e. higher densities of silver grains) than do females (B). Similar differences were obtained in the portion of the medial striatum which contains area X in males (C), although area X is not morphologically distinct in females (D), and in RA (robust nucleus of the arcopallium, panels E = males, F = females). However, in HVC, no specific labeling was detected in either sex (panel G = male, panel H = female). Scale bar = 200 μm for lMAN and area X; 100 μm for HVC and RA.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2664819&req=5

Figure 2: Darkfield images from in situ hybridization depicting sexually dimorphic mRNA expression for CK303566in the zebra finch song system at day 25 post-hatching. Arrows delineate borders of song regions. This gene showed the most extensive sex differences in expression. In lMAN (lateral magnocellular nucleus of the anterior nidopallium) males (A) show higher levels of mRNA expression (i.e. higher densities of silver grains) than do females (B). Similar differences were obtained in the portion of the medial striatum which contains area X in males (C), although area X is not morphologically distinct in females (D), and in RA (robust nucleus of the arcopallium, panels E = males, F = females). However, in HVC, no specific labeling was detected in either sex (panel G = male, panel H = female). Scale bar = 200 μm for lMAN and area X; 100 μm for HVC and RA.
Mentions: Specific expression of CK303566 was detected in lMAN, Area X and RA, but not HVC (Figure 2). The density of labeling was greater in males than females in all three areas (lMAN: t = 3.32, p = 0.008; Area X: t = 3.35, p = 0.007; RA: t = 3.89, p = 0.003; Table 3).

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Psychology & Program in Neuroscience, Michigan State University, East Lansing, MI, USA. tomaszy1@msu.edu

ABSTRACT

Background: 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.

Results: A 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.

Conclusion: The 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.

Show MeSH
Related in: MedlinePlus