Transcription of the sex-determining region genes Sry and Zfy in the mouse preimplantation embryo.

Abstract

We have confirmed the faster growth of male preimplantation mouse embryos. We have also studied the transcription of Y chromosomal genes postulated to have a role in sex determination, using the highly sensitive technique of reverse-transcription polymerase chain reaction at these early stages. We find that two sex-determining region genes (2), is an exciting advance for studies of sex determination. The finding that 40,XY female mice (3) had a deletion in this gene (2) and the identification of point mutations in this gene in some human 46,XY females (4) were highly supportive of the postulated role of this gene in sex determination. However, the most convincing proof has been the demonstration of sex reversal in some 40,XX mice transgenic for the mouse genomic clone (5). Studies on expression of Sry have focused on its transcription in presumptive Sertoli cells in the gonadal ridge at the time of gonadal differentiation-i.e., 11.5 days (6). These authors used the We mutation to show that the transcription at that time did not require germ cells. The earliest stage studied in this report was the embryonic stage at 7.5 days postcoitus, and no transcription was found until 11.5 days (6). We find much earlier transcription-as early as the two-cell stage.There had been previous evidence of differences in gene expression between male and female embryos. Although it was somewhat controversial at first, it is now well established that the male-specific antigen (MSA, serological H-Y) is detectable on preimplantation embryos (7,8). It is clear that a "growth factor" on the Y chromosome is expressed early, since embryos separated as to early blastulation (fast developers) versus late blastulation (slow developers) are predominantly male in the first group (9). We have now confirmed this effect for the preimplantation mouse embryo by a method not requiring embryo transfer, whereas others have shown that it persists to midgestation (10, 11) and also occurs in Bovidae (12, 13). Sry or Zfy (Y chromosome-linked zinc finger protein) transcription may be related to these differences.MATERIALS AND METHODS Chemicals. Pregnant mare serum gonadotropin, human chorionic gonadotropin (hCG), and most chemicals were from Sigma. The Micro-FastTrack mRNA isolation kit was from Invitrogen (San Diego), the reverse-transcription system and "fmol" DNA sequencing systems were from Promega, and the PCR purification spin kit was from Quiagen (Studio City, CA).Animals. Animals were from The Jackson Laboratory or were bred from their stock in our colony. Twenty-one-dayold (C57BL/6J x SJL/J)F1 female mice were superovulated by interaperitoneal injections of 5 units of pregnant mare serum gonadotropin followed by S units of human chorionic gonadotropin 48 hr later and then were mated with F1 males of the same cross. The time of coitus and fertilization was assumed to be at midnight after mating.Rate of Development of Male Versus Female Embryos. Embryos were flushed from the oviducts on day 1 and cultured in vitro. They were classified as to...

Differential expression of two genes located on the X chromosome between male and female in vitro-produced bovine embryos at the blastocyst stage

“…However, the activity of some unknown genes of the X chromosome should also play an important role in the developmental differences between male and female embryos before gonadal sex determination has taken place (Zwingman et al, 1993;Pergament et al, 1994). Sexlinked differential expression of some genes prior to implantation has been demonstrated: male-specific serological H-Y antigen (White et al, 1983), ZFY/ZFX genes in murine, human, and ovine embryos (Zwingman et al, 1993;Ao et al, 1994;Bernardi et al, 1996), and SRY transcription in bovine, human, and murine embryos (Zwingman et al, 1993;Ao et al, 1994;Fiddler et al, 1995;Gutiérrez-Adá n et al, 1997). However, no functional role has been associated to this difference.…”

A Novel Sex-Determining Region on Y(SRY) Missense Mutation Identified in a 46, XY Female and also in the Father.

“…The arginine at position 76 is not strictly conserved among the different HMG domain proteins, but it is the most frequently found residue at that position [20,21]. The presence of de novo inactivating mutations in XY females, the presence of SR Y in males with 46, XX maleness [3,21], and the fact that introduction of a mouse SR Y transgene into karyotypic female mouse embryos results in testis formation and male development [21][22][23] implicate SR Y as necessary for male sex determination. However, mutations in SR Y explain only 10-15% of the cases of 46, XY females.…”

The Genetics and Biology of Sex Determination (Novartis Foundation Symposia #244), edited by Derek Chadwick and Jamie Goode

“…While the book provides an excellent overview of current results and delineation of problems in vertebrate sex determination, the choice of a selected audience means that some aspects are ignored. For instance, the finding that SRY/Sry is transcribed in the preimplantation embryo [Zwingman et al, 1993;Ao et al, 1994;Cao et al, 1995] is not mentioned. Also, despite Ursula Mittwoch's presence, there is very little discussion of the mechanisms of increased growth of male fetuses and fetal gonads.…”