title: Sexual dimorphism in the early embryogenesis of the chicken (Gallus Gallus domesticus).
abstract: Studies of dioecious animals suggest that sex-specific development occurs from the onset of embryogenesis. This must be accounted for when addressing issues involving sex-ratio regulation in domestic animals and conservation biology. We investigated the occurrence of growth-rate sexual dimorphism in 84 chicken embryos incubated for 30 hr and nucleic-acid abundance in 99 embryos incubated for 4 hr. Comparative expression of the genes engaged in cell-cycle regulation (16 genes), embryo growth (10 genes), metabolic activity (2 genes), and epigenetic regulation (4 genes) in 4-hr male and female embryos were further analyzed by reverse-trancriptase quantitative PCR. At the stage when somite structure commences, males are growing faster than females. DNA and RNA yields at 4 hr are elevated in males compared to females, and most cell-proliferation-promoting genes are overexpressed in males. Expression of key metabolic genes (G6PD and HPRT) and the principal genes responsible for DNA methylation (DNMTs), however, does not differ between the sexes. These data suggest that the faster growth of early male embryos is conserved among mammalian and bird phyla, and may have an evolutionary importance.
authors.affiliation: Poultry Research Institute, Ukrainian Academy of Agrarian Sciences, Borky, Zmiiv District, Kharkiv Region, Ukraine.
authors.forename: Makhsud
authors.initials: M
authors.lastname: Tagirov
authors.affiliation: Department of Animal and Food Science, University of Delaware, Newark, Delaware.
authors.forename: Serguei
authors.initials: S
authors.lastname: Golovan
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000235:genetics; D002642:Chick Embryo; D002645:Chickens / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics; D047108:Embryonic Development / Q000235:genetics*; D044127:Epigenesis, Genetic; D005260:Female; D018507:Gene Expression Regulation, Developmental; D007328:Insulin / Q000378:metabolism; D008297:Male; D053858:Metabolic Networks and Pathways / Q000235:genetics; D012727:Sex Characteristics; D012744:Sex Ratio
chemical_list: D004275:DNA, Ribosomal; D007328:Insulin