Sex-dependent gene expression in early brain development of chicken embryos.
BACKGROUND
Differentiation of the brain during development leads to sexually dimorphic adult reproductive behavior and other neural sex dimorphisms. Genetic mechanisms independent of steroid hormones produced by the gonads have recently been suggested to partly explain these dimorphisms.


RESULTS
Using cDNA microarrays and real-time PCR we found gene expression differences between the male and female embryonic brain (or whole head) that may be independent of morphological differentiation of the gonads. Genes located on the sex chromosomes (ZZ in males and ZW in females) were common among the differentially expressed genes, several of which (WPKCI-8, HINT, MHM non-coding RNA) have previously been implicated in avian sex determination. A majority of the identified genes were more highly expressed in males. Three of these genes (CDK7, CCNH and BTF2-P44) encode subunits of the transcription factor IIH complex, indicating a role for this complex in neuronal differentiation.


CONCLUSIONS
In conclusion, this study provides novel insights into sexually dimorphic gene expression in the embryonic chicken brain and its possible involvement in sex differentiation of the nervous system in birds.
Division of Toxicology, Department of Pharmaceutical Biosciences, The Biomedical Center, Husargatan 3, Box 594, SE-75124 Uppsala, Sweden. Birger.Scholz@farmbio.uu.se
Birger
B
Scholz
Kim
K
Kultima
Anna
A
Mattsson
Jeanette
J
Axelsson
Björn
B
Brunström
Krister
K
Halldin
Michael
M
Stigson
Lennart
L
Dencker
D000367:Age Factors; D000818:Animals; D001921:Brain / Q000196:embryology* / Q000378:metabolism*; D002642:Chick Embryo; D015870:Gene Expression / Q000502:physiology*; D017403:In Situ Hybridization / Q000379:methods; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012727:Sex Characteristics; D012730:Sex Chromosomes / Q000235:genetics; D019849:Sex Determination Processes; D012733:Sex Differentiation / Q000502:physiology
D012333:RNA, Messenger