International Mammalian Genome Society

17th International Mouse Genome Conference

9-12 November 2003, Braunschweig, Germany


ORAL PRESENTATION

MONDAY 10 NOVEMBER
15:30 – 15:45 HRS

REPRODUCTIVE ISOLATION AS A COMPLEX TRAIT: TOWARDS GENETIC ARCHITECTURE OF HYBRID STERILITY IN THE MOUSE

Forejt J
Centre of Integrated Genomics, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic

Co-Authors: Trachtulec Z, Aixnerová R, Gregorova S, Krizan J, Divina P, Vlcek C, Paces V, Vacík T, Jansa P
Institutions: Centre of Integrated Genomics, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic

Hybrid sterility is a postzygotic reproductive isolation mechanism that has been extensively studied in Drosophila species and more recently in species and subspecies of genus Mus. We have studied a model system of male-sterile F1 hybrids between a laboratory inbred strain C57BL/6 (B6), predominantly of Mus m. domesticus origin and PWD/Ph strain, derived from Mus m. musculus wild mice. Using a QTL approach we asked (1) how many genes govern the sterility of hybrids, (2) where in the genome are the hybrid sterility (Hst) loci situated and (3) how they interact. Over 700 males from (PWDxB6)xB6 and (PWDxB6)xPWD backcrosses were analyzed for testis weights and sperm counts, indicators of spermatogenesis arrest. We have found (rather unexpectedly) only three major loci controlling hybrid sterility, on chromosomes X, 17 and 13. The epistatic interaction between all three loci is necessary for the full-blown sterility with intrameiotic arrest. The locus on Chromosome 17 is most likely identical to the Hst1 gene, which was mapped in our laboratory more than 25 years ago. At present 6 candidate genes for the Hst1 locus are identified in a critical 360 kb region. Verification of the X-linked Hst locus using the B6-XPWD consomic strain revealed several X-linked loci, which render the males sterile. However, this type of sterility was mostly postmeiotic. Comparison of our results with the genetic architecture of hybrid sterility of other mouse (sub)species hybrids, as well as with studies on Drosophila hybrids, may help to uncover the nature of speciation genes.


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