Submitted to: Journal of Heredity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2007
Publication Date: 3/29/2007
Citation: Granevitze, Z., Blum, S., Cheng, H.H., Vignal, A., Morisson, M., Ben-Ari, G., David, L., Feldman, M.W., Weigend, S., Hillel, J. 2007. Female-specific DNA sequences in the chicken genome. Journal of Heredity. 98:238-242. Interpretive Summary: It has been widely stated that future advances in poultry breeding and health will come through biotechnology and genomic resources. One key resource released in 2004 was the generation of the draft genome sequence of the chicken genome. By having the "blueprint" of the chicken, it was envisioned that it would be much easier to identify genes of agricultural importance. There has been a long-term interest in the sex chromosomes and particularly chromosome W as this is specific to females. By identifying "female-specific" sequences, it may shed light on sex determination and sex chromosome evolution. In this paper, we demonstrate which chromosome W sequences are truly female specific, which also indicates that this draft genome assembly had errors. Ultimately, these studies should provide functional annotation to the chicken genome, a top priority for biological scientists.
Technical Abstract: Female-specific regions in the chicken's genome were detected in silico. Eight fragments out of 21 that were in-silico W-specific, were shown to produce PCR products only in females. Some of these fragments gave a female-specific product in turkeys and peacocks. We sequenced all eight fragments in one bird from each of ten highly divergent chicken populations; the total length of the fragments is 3077 bp. No polymorphism was detected in any of these fragments among the ten chicken populations. In contrast, comparison between the DNA sequences of the chicken with sequences from turkey and peacock, SNP was discovered every 25 bp and 28 bp, respectively. Female specific PCR amplifications for the eight fragments, supported by Radiation hybrid (RH) mapping verified that these fragments exist only on chromosome W, and therefore they are not pseudo-autosomal regions. The homology of six W-specific fragments with chromo-helicase-DNA-binding (CHD1) gene and with ESTs extracted from chicken and other species indicated that these fragments may have a biological function. Since these fragments are W-specific it is possible that their biological role, if any, is related to sex determination mechanism. These fragments may be used for early sexing in commercial chicken and turkey flocks. They may also be useful in future evolutionary studies of sex chromosomes in poultry and other avian species.