International Mammalian Genome Society

17th International Mouse Genome Conference

9-12 November 2003, Braunschweig, Germany

Plenary Presentations * Oral Presentations *
Poster Presentations: Behavioural Genetics and Genomics * Development and Stem Cells * Functional Genome Analysis * Mouse Models of Human Disease * Mouse System Biology Bioinformatics * Multigenic and Multifactorial Trait Analysis * Nutrition and Metabolic Disease * Phenotyping Methods Imaging * The Genetics and Genomics of Infectious Disease *
Verne Chapman Memorial Lecture * Table of Contents * Sponsor/Exhibitor List * Awards * Photographs

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POSTER 177 - GENETIC INCOMPATIBILITY BETWEEN X-LINKED LOCI AND TWO AUTOSOMAL REGIONS CAUSES HYBRID BREAKDOWN BETWEEN TWO MOUSE SUBSPECIES

Oka A
Department of Mammalian Genetics, National Institute of Genetics

Co-Authors: 1) Mita A, 1) Sakurai N, 1) Yamamoto H, 2) Takagi N, 3) Takano-Shimizu T, 4) Toshimori K, 5) Moriwaki K, 1) Shiroishi T
Institutions: 1) Department of Mammalian Genetics, National Institute of Genetics, 2) Hokkaido University, 3) Department of Population Genetics, National Institute of Genetics, 4) Chiba University 5) RIKEN BioResource Center

Hybrid breakdown is a type of reproductive failure that appears after F₂ generation of crosses between different species or subspecies. It is caused by incompatibility between alleles of interacting genes. We have studied the hybrid breakdown using a consomic strain, C57BL/6J-X ^MSM, in which the X chromosome of C57BL/6J (derived mostly from Mus musculus domesticus) is substituted by the X chromosome of the MSM/Ms strain (M. m. molossinus). Males of this consomic strain are sterile due to the abnormal sperm head morphology, whereas F₁ hybrids between C57BL/6J and MSM/Ms are completely fertile. This finding implies that incompatibility between X-linked gene(s) and other chromosomal gene(s) causes the hybrid breakdown observed in C57BL/6J-X^MSM. The previous our study revealed that at least three X-linked QTLs are responsible for the sperm head abnormality and the hybrid breakdown. We conducted the whole-genome scan to detect autosomal and/or Y chromosomal regions, which interact with the X-linked QTLs and underlie the genetic incompatibility. The result suggested that Chromosome 1 and 11 interact with the X-linked QTLs for proper male reproduction in parental MSM/Ms strain, and disruption of this interaction causes the hybrid breakdown. Furthermore, we characterized the sperm head abnormality in detail in C57BL/6J-X^MSM. In spermiogenesis, nuclear protein histone is replaced by protamine, spermatid- and sperm-specific basic proteins, and it leads to chromatin condensation in spermatids. We found that this replacement did not occur properly in C57BL/6J-X^MSM, which may cause the abnormal sperm head morphology.