BIOCHEMICAL GENETICS OF MALE SEXUAL DETERMINATION

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We seek to understand molecular events involved in the differentiation of the mammalian male embryonic gonad. Such knowledge should be of benefit for improved diagnosis, and possibly prenatal diagnosis, of human intersex conditions as well as increasing our understanding of normal human development. Our studies will use both mouse models and human material. Studies in mice will focus on genetic loci in the proximal arm of chromosome 17 which interact with the mouse Y chromosome (which also has variants) to try and elucidate how these autosomal loci interact with the Y chromosome and other autosomal loci in contributing to normal testicular development. Among the loci on chromosome 17 may be those containing Banded krait minor satellite (Bkm) sex specific sequences. Since certain large deletions (T-Or1 and T-Hp) in this area of chromosome 17 can cause hermaphroditism, we will determine whether or not these deletions alter the amounts of Bkm-sequences detected on chromosome 17 by in situ hybridization. We will use the Bkm probe to look for mRNAs containing Bkm sequences in mouse and human fetal gonads and appropriate other tissues. Cosmid clones from the proximal region of mouse chromosome 17 and lambda clones from the human X chromosome will be screened with a Bkm probe. Subportions of positive clones will be used to screen fetal gonad RNA. The human Y chromosomal clones previously obtained, and new ones obtained by PERT and chromosome "hop" techniques, will be used to study XX males and their parents in an attempt to determine the source of the Y chromosomal DNA usually found in such XX males. The work on human material will also use human Y chromosome clones to look for expressed Y sequences in the male fetal gonad. Genomic clones corresponding to mouse or human male fetal gonad specific expressed sequences will be sought by screening cDNA libraries with the identified probe and using the cDNA clone to screen genomic clones (when the probe is not unique sequence).