title: Interallelic and intergenic incompatibilities of the Prdm9 (Hst1) gene in mouse hybrid sterility.
abstract: The Dobzhansky-Muller model of incompatibilities explains reproductive isolation between species by incorrect epistatic interactions. Although the mechanisms of speciation are of great interest, no incompatibility has been characterized at the gene level in mammals. The Hybrid sterility 1 gene (Hst1) participates in the arrest of meiosis in F(1) males of certain strains from two Mus musculus subspecies, e.g., PWD from M. m. musculus and C57BL/6J (henceforth B6) from M. m. domesticus. Hst1 has been identified as a meiotic PR-domain gene (Prdm9) encoding histone 3 methyltransferase in the male offspring of PWD females and B6 males, (PWD×B6)F(1). To characterize the incompatibilities underlying hybrid sterility, we phenotyped reproductive and meiotic markers in males with altered copy numbers of Prdm9. A partial rescue of fertility was observed upon removal of the B6 allele of Prdm9 from the azoospermic (PWD×B6)F(1) hybrids, whereas removing one of the two Prdm9 copies in PWD or B6 background had no effect on male reproduction. Incompatibility(ies) not involving Prdm9(B6) also acts in the (PWD×B6)F(1) hybrids, since the correction of hybrid sterility by Prdm9(B6) deletion was not complete. Additions and subtractions of Prdm9 copies, as well as allelic replacements, improved meiotic progression and fecundity also in the progeny-producing reciprocal (B6×PWD)F(1) males. Moreover, an increased dosage of Prdm9 and reciprocal cross enhanced fertility of other sperm-carrying male hybrids, (PWD×B6-C3H.Prdm9)F(1), harboring another Prdm9 allele of M. m. domesticus origin. The levels of Prdm9 mRNA isoforms were similar in the prepubertal testes of all types of F(1) hybrids of PWD with B6 and B6-C3H.Prdm9 despite their different prospective fertility, but decreased to 53% after removal of Prdm9(B6). Therefore, the Prdm9(B6) allele probably takes part in posttranscriptional dominant-negative hybrid interaction(s) absent in the parental strains.
authors.affiliation: Department of Mouse Molecular Genetics and Center for Applied Genomics, Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Flachs
authors.forename: Ondřej
authors.initials: O
authors.lastname: Mihola
authors.forename: Petr
authors.initials: P
authors.lastname: Simeček
authors.forename: Soňa
authors.initials: S
authors.lastname: Gregorová
authors.forename: John C
authors.initials: JC
authors.lastname: Schimenti
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Matsui
authors.forename: Frédéric
authors.initials: F
authors.lastname: Baudat
authors.forename: Bernard
authors.initials: B
authors.lastname: de Massy
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Piálek
authors.forename: Jiří
authors.initials: J
authors.lastname: Forejt
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Trachtulec
mesh_terms: D000483:Alleles; D000818:Animals; D002678:Chimera / Q000235:genetics / Q000502:physiology; D002874:Chromosome Mapping; D004843:Epistasis, Genetic; D005260:Female; D005298:Fertility / Q000235:genetics; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics*; D006824:Hybridization, Genetic; D007248:Infertility, Male / Q000235:genetics*; D008297:Male; D008540:Meiosis; D051379:Mice; D060047:Reproductive Isolation
chemical_list: D011495:Histone-Lysine N-Methyltransferase; C534829:prdm9 protein, mouse