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Unformatted text preview: PHYSIOLOGY AND REPRODUCTION Profiles of mRNA Expression of Genes Related to Sex Differentiation of the Gonads in the Chicken Embryo I. Yamamoto, A. Tsukada, N. Saito, and K. Shimada 1 Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, 464-8601 Japan ABSTRACT Sex is determined genetically in birds. The homogametic sex is male (ZZ), whereas the heterogametic sex is female (ZW). According to the genetic sex, gonads develop into testes or ovary. In this study, we performed experiments to reveal mRNA expression patterns in the gonad between d 5.5 and 8.5 of incubation and examined a possible role of Dss-Ahc critical region on the X chromo- some 1 (Dax1), Steroidogenic factor 1 (Sf1), P450aroma- tase (P450arom), Estrogen receptor α (ER α ), doublesex and mab3 related transcription factor 1 (Dmrt1), Sry-related HMG box gene 9 (Sox9), Gata binding protein 4 (Gata4), and anti-mu ¨llerian hormone (Amh) in sex differentiation in chicken embryonic gonads using RNase protection assay. In embryonic chicken gonads, Dax1 mRNA was ex- pressed in both sexes but was higher in females than in males at d 6.5 and 7.5 of incubation. The Sf1 mRNA was expressed in both sexes, but it was expressed more in ( Key words : chicken, embryo, gonad, sex differentiation, mRNA expression) 2003 Poultry Science 82:1462–1467 INTRODUCTION The sex is determined genetically in mammals and birds. In mammals, heterogametic sex is male (XY), whereas homogametic sex is female (XX). According to the genetic sex, gonads develop into testes or ovary. The Sex-determining region Y ( Sry ) is the testis-determining gene in mammals (Sinclair et al., 1990; Koopman et al., 1991). It encodes a transcription factor and includes a critical region of HMG (high mobility group) box. Sry controls testis formation, but the direct targets of Sry remain to be identified. A downstream gene in the cas- cade of sex determination mechanism is Sry-related HMG box gene 9 ( Sox9 ), which encodes a transcription factor including HMG box. Sox9 acts as a male-determining gene in the embryonic gonad. Sox9 activates Anti-mu ¨lle- rian hormone ( Amh ) mRNA expression with Steroidogenic 2003 Poultry Science Association, Inc. Received for publication December 17, 2002. Accepted for publication April 4, 2003. 1 To whom correspondence should be addressed: [email protected] nagoya-u.ac.jp. 1462 males at d 5.5 than in females but more in females than in males at d 7.5 and 8.5 of incubation. The P450arom mRNA was expressed only in female gonads from d 5.5 of incubation. The ER α mRNA was expressed in both sexes, but it did not show a sex difference. On the other hand, the Dmrt1 mRNA was expressed in both sexes, but it showed a male-specific expression pattern. The male- specific expression pattern was observed in Sox9 mRNA, but it was not expressed in female gonads. The Gata4 mRNA was expressed in both sexes, and sex differences were not revealed throughout the observational period.were not revealed throughout the observational period....
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This note was uploaded on 07/28/2011 for the course VET 4335 taught by Professor Sakomura during the Spring '11 term at University of the South Pacific, Fiji.
- Spring '11