Proper genetic and epigenetic regulation of the sex chromosomes during spermatogenesis is crucial for the development of normal male fertility. The sex chromosomes also play a central role in the evolution of hybrid male sterility between species, but the developmental causes of these incipient reproductive barriers remain unclear. The proposed research will use quantitative genetic and genomic experiments in house mice to bridge significant gaps in our understanding of the developmental underpinnings of male sterility. Mice are the predominant genetic models for human reproductive biology, thus male sterility can be studied in greater detail in mice than in most other systems. Here we focus on two closely related mouse species that are partially isolated by hybrid male sterility, providing an ideal model system for studying the consequences of natural genetic divergence on the progression of spermatogenesis. One of our central goals is to test the long- standing hypothesis that regulatory disruption of X-inactivation during spermatogenesis plays a central role in the evolution of hybrid sterility. Towards this end, we are proposing four synergistic research projects. First, we will use cutting-edge sequencing approaches to generate complete genomic sequences for our study organisms. Second, we will use powerful methods of targeted cellular enrichment to study gene expression across key stages of spermatogenesis in two species of mice and their sterile hybrid males. These data will be used to determine if the disruption of X-linked gene regulation during the later stages of spermatogenesis is a primary developmental cause of hybrid male sterility in mice. We will also use these data to identify candidate genes involved in the underlying genetic interactions that disrupt spermatogenesis. Third, we will use additional genetic experiments to directly test if candidate incompatibilities do indeed interact with the X chromosome to cause sterility. Fourth, we will use quantitative genetic methods to further dissect one set of incompatibilities where one or more of the interacting genes that cause hybrid male sterility remain polymorphic within one of the species. This final set of experiments will utilize the extensive genetic resources of the mouse system to study the evolution of hybrid incompatibilities at their earliest possible stage - prior to their fixation between species. Collectively, these experiments will provide important insights into the developmental causes of male sterility.

Public Health Relevance

Sterility is a major health concern and the genetic causes of many male infertility diseases remain elusive. We propose four synergistic research projects to dissect the genetic basis of male sterility between two species of mice. These experiments will use the powerful resources available through the mouse system to provide important insights into the developmental underpinnings of male sterility.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
4R01HD073439-05
Application #
9081238
Study Section
Genetic Variation and Evolution Study Section (GVE)
Program Officer
Taymans, Susan
Project Start
2012-07-26
Project End
2017-05-31
Budget Start
2016-06-01
Budget End
2017-05-31
Support Year
5
Fiscal Year
2016
Total Cost
Indirect Cost
Name
University of Montana
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
010379790
City
Missoula
State
MT
Country
United States
Zip Code
59812
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Larson, Erica L; Kopania, Emily E K; Good, Jeffrey M (2018) Spermatogenesis and the Evolution of Mammalian Sex Chromosomes. Trends Genet 34:722-732
Phifer-Rixey, Megan; Bi, Ke; Ferris, Kathleen G et al. (2018) The genomic basis of environmental adaptation in house mice. PLoS Genet 14:e1007672
Bracewell, Ryan R; Bentz, Barbara J; Sullivan, Brian T et al. (2017) Rapid neo-sex chromosome evolution and incipient speciation in a major forest pest. Nat Commun 8:1593
Chang, Peter L; Kopania, Emily; Keeble, Sara et al. (2017) Whole exome sequencing of wild-derived inbred strains of mice improves power to link phenotype and genotype. Mamm Genome 28:416-425
Sarver, Brice A J; Keeble, Sara; Cosart, Ted et al. (2017) Phylogenomic Insights into Mouse Evolution Using a Pseudoreference Approach. Genome Biol Evol 9:726-739
Larson, Erica L; Keeble, Sara; Vanderpool, Dan et al. (2017) The Composite Regulatory Basis of the Large X-Effect in Mouse Speciation. Mol Biol Evol 34:282-295
Larson, Erica L; Vanderpool, Dan; Keeble, Sara et al. (2016) Contrasting Levels of Molecular Evolution on the Mouse X Chromosome. Genetics 203:1841-57
Harrison, Richard G; Larson, Erica L (2016) Heterogeneous genome divergence, differential introgression, and the origin and structure of hybrid zones. Mol Ecol 25:2454-66
Andrews, Kimberly R; Good, Jeffrey M; Miller, Michael R et al. (2016) Harnessing the power of RADseq for ecological and evolutionary genomics. Nat Rev Genet 17:81-92

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