Transcription profiling of chicken 18 day embryonic chicken heart, brain, and gonad to determine sex specific gene expression

ABSTRACT: The contrasting dose of sex chromosomes in males and females potentially introduces a large-scale imbalance in levels of gene expression between sexes. In many organisms dosage compensation has thus evolved to equalize sex-linked gene expression in males and females1,2, in mammals achieved by X chromosome inactivation and in flies and worms by up- or down-regulation of X-linked expression, respectively. Another form of dosage compensation ensures that expression levels on the X chromosome and on autosomes are balanced3,4. While otherwise widespread in systems with heteromorphic sex chromosomes, the case of dosage compensation in birds (males ZZ, females ZW) remains an unsolved enigma5,6. Here we use a microarray approach to show that male day 18 chicken embryos generally express higher levels of Z-linked genes than female birds, both in soma and in gonads. The distribution of male-to-female fold-change values for Z chromosome genes is wide and has a mean of 1.4-1.6, which is consistent with absence of dosage compensation and sex-specific feedback regulation of gene expression at individual loci2. Intriguingly, without global dosage compensation, female chicken has significantly lower expression levels of Z-linked compared to autosomal genes, which is not the case in male birds. The pronounced sex difference in gene expression is likely to contribute to sexual dimorphism among birds, and potentially has implication to avian sex determination. Experiment Overall Design: Sample collection Experiment Overall Design: Fertilized eggs from White Leghorn fowl were purchased from OVA Production (MorgongM-CM-%va, Sweden). The eggs were incubated at 37.5C and 60% relative humidity, and were turned every 3 hours. After 18 days of incubation (ed18), the embryos were euthanized by decapitation. A piece from the apical part of the heart was collected and the left gonad and the brain were excised. The cerebellum, the optic lobes and the cerebral hemispheres were removed from the brain and, consequently, the brain sample included the intact diencephalon and remaining parts from other regions. The samples were immediately frozen in liquid nitrogen and then stored at -70 M-BM-0C. The embryos were sexed by ocular inspection of the gonads and MM-CM-

ORGANISM(S): Gallus gallus

SUBMITTER: judith mank 

PROVIDER: E-GEOD-8693 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress