In mammals, anti-Mu ¨llerian hormone (AMH) is produced by Sertoli cells from the onset of testicular differentiation and by granulosa cells only after birth. SOX9, a transcription factor related to the testis-determining factor SRY, is expressed in mouse testis 1 day before AMH. To determine the relationship between AMH and SOX9 in birds, we cloned the AMH promoter in search of SOX9 response elements, and we compared the expression of AMH and SOX9 in the gonads of chick embryos using in situ hybridization. Potential SOX response elements were found in the AMH promoter; however, AMH is expressed in both sexes at stage 25, 1 day before the first SOX9 transcripts appear in the male gonads. SOX9 is never expressed in the female. These results do not support the hypothesis that SOX9 could trigger the expression of testicular AMH in the chick but does not exclude a later role in testis development.

Anti-Müllerian hormone (AMH) and its receptor are involved in the regression of Müllerian ducts in male fetuses. We have now cloned and mapped the human AMH receptor gene and provide genetic proof that it is required for AMH signalling, by identifying a mutation in the AMH receptor in a patient with persistent Müllerian duct syndrome. The mutation destroys the invariant dinucleotide at the 5' end of the second intron, generating two abnormal mRNAs, one missing the second exon, required for ligand binding, and the other incorporating the first 12 bases of the second intron. The similar phenotypes observed in AMH-deficient and AMH receptor-deficient individuals indicate that the AMH signalling machinery is remarkably simple, consisting of one ligand and one type II receptor.

In mammals, anti-Mü llerian hormone (AMH) is produced by Sertoli cells from the onset of testicular differentiation and by granulosa cells after birth. In birds, AMH starts to be expressed in indifferent gonads of both sexes at a similar level and is later upregulated in males. We previously demonstrated that, unlike in mammals, the onset of AMH expression occurs in chick embryo in the absence of SOX9. We looked for potential factors that might be involved in regulating AMH expression at different stages of chick gonad differentiation by comparing its expression pattern in embryos and young chicken with that of DMRT1, SF-1, WT1, GATA-4, Wnt-4, and

Anti-Müllerian hormone (AMH) is best known for its role as an inhibitor of the development of female internal genitalia primordia during fetal life. In the testis, AMH is highly expressed by Sertoli cells of the testis from early fetal life to puberty, when it is downregulated by the action of testosterone, acting through the androgen receptor, and meiotic spermatocytes, probably acting through TNFalpha. Basal expression of AMH is induced by SOX9; GATA4, SF1, and WT1 enhance SOX9-activated expression. When the hypothalamic-pituitary axis is active and the negative effect of androgens and germ cells is absent, for example, in the fetal and neonatal periods or in disorders like androgen insensitivity, FSH upregulates AMH expression through a nonclassical cAMP-PKA pathway involving transcription factors AP2 and NFkappaB. The maintenance and hormonal regulation of AMH expression in late fetal and postnatal life requires distal AMH promoter sequences. In the ovary, granulosa cells express AMH from late fetal life at low levels; DAX1 and FOG2 seem to be responsible for negatively modulating AMH expression. Particular features are observed in AMH expression in nonmammalian species. In birds, AMH is expressed both in the male and female fetal gonads, and, like in reptiles, its expression is not preceded by that of SOX9.

No abstract

The persistent Müllerian duct syndrome (PMDS) is a rare form of male pseudohermaphroditism, characterized by the persistence of Müllerian derivatives in otherwise normal males. Two mutations, present in the homozygous state, have been previously described in such patients. The present observation is the first example of compound heterozygosity in this condition. DNA was obtained from a 3-month-old patient with PMDS, in whom no serum anti-Müllerian hormone (AMH) could be detected by enzyme-linked immunosorbent assay. Sequencing of cloned polymerase chain reaction amplified fragments of the AMH gene revealed a 14-bp deletion in the second exon of the maternal allele; this deletion disrupted the open reading frame. It occurred at a site containing two 8-bp direct repeats flanking a 6-bp sequence and removed one whole repeat plus all of the intervening sequence. It may be the result of a slipped mispairing at the DNA replication fork. The paternal allele contains a stop mutation in the third exon. These two mutations, impairing both AMH alleles, are consistent with the occurrence of PMDS, and are shared with a phenotypically normal younger sister. In this family, various other mutations, devoid of physiological significance, suggest that the AMH gene is highly polymorphic.

Two basic proteins, protamines PI and P2, are present in chromatin of mouse spermatozoa. Protamine P1, the less abundant protein in mouse, has a homolog in most mammals, and its synthesis follows a conventional route. In contrast, protamine P2 has been found only in certain other mammals, including humans, and it is synthesized as a precursor nearly twice as long as the mature protein. Processing of this precursor is not yet understood, although it necessarily takes place in elongating spermatids and is likely to play a role in the chromatin condensation occurring in these haploid cells.We have fractionated basic proteins from mouse testis chromatin and have identified six proteins on electrophoretic gels which, like protamines, are insoluble in SDS. All six were also soluble at the same trichloroacetic acid concentration as protamine P2 and were present in chromatin of elongating spermatids. Radioactive labelling patterns acquired by these SDS-insoluble proteins during translation in vitro of testis RNA indicate that the largest represents the precursor of protamine P2, and suggest that the others represent intermediates generated by proteolytic cleavage of the precursor. Results from pulse 3H labelling in vivo were also consistent with the conclusion that a precursor/product relationship exists between these proteins and protamine P2. Conclusions concerning the kinetics of processing have, in addition, been drawn from this data. Hypotheses concerning possible functional roles played by the precursor are presented.During mammalian spermatogenesis, histones in the chromatin of haploid germ cells are replaced by transition proteins [l -41, and these are replaced subsequently by arginine-and cysteine-rich protamines [5 -81. Two protamines, P1 [9] and P2 [lo], are present in mouse spermatozoa. Protamine P1, the less abundant in mouse, appears to have a homolog in most, if not all, mammals [ll -201 and a related protamine has been found in birds [21, 221. In contrast, homologs of mouse protamine P2 have been found only in a few other mammals including man [ l l , 231, stallion [19, 201, and hamster [18], where protamines P1 and P2 are present in species-specific proportions. Mouse protamines P1 and P2 are encoded by single-copy genes, which are closely linked and located on chromosome 16 [24].Several aspects of protamine gene expression have also been studied in mouse, including identification of probable signals for transcription regulation in genomic DNA [25 -271 and analysis of post-meiotic mRNA production and storage [28-321, all of which appear to be similar for protamines P1 and P2. Translation, however, reveals a major difference between the two proteins. Protamine P1 is synthesized as a protein of mature length which is incorporated into chromatin perhaps via a series of reactions involving protein phosphorylation [5,33, 341. Production of protamine P2 involves synthesis of a precursor which is almost twice as long as the mature protein found in spermatozoa. Our earlier studies using translation in vitro of...

Evidence for a selection pressure at the protein level suggests that this endogenous retrovirus, expressed in the ovarian supporting cell lineage, might play an active role in bird ovarian physiology.