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Most classical Mus musculus domesticus laboratory mouse strains carry a Mus musculus musculus Y chromosome
Abstract:
Restriction fragment length polymorphisms (RFLPs) of maternally inherited mitochondrial DNA have revealed that genetic exchanges can occur between populations, subspecies or even species. From the point of view of population genetics the mammalian Y chromosome represents a genomic analogue of the mitochondrion; it is inherited only paternally and remains perpetually monosomic, showing little meiotic recombination with other chromosomes. Using a Y-specific genomic DNA probe obtained from a flow-sorted mouse Y-chromosome library, we have examined the RFLPs in 10 newly established mouse lines of the European semispecies Mus musculus domesticus and Mus musculus musculus, and identified two variant forms of the Y chromosome, each of which is characteristic of one of the semispecies. As reported here, probing the DNA from nine established inbred laboratory strains reveals that the strain SJL carries a M.m. domesticus type Y whereas, surprisingly, the Y chromosomes of the other eight strains are of M.m. musculus origin. Hence, these strains cannot be regarded as archetypes of M.m. domesticus as suggested by protein polymorphisms and mitochrondrial DNA sequence data, but rather as genetic hybrids between the two semispecies.
Insights
Mitochondrial DNA studies show genetic exchange. Researchers found distinct Y chromosomes in Mus musculus domesticus and Mus musculus musculus semispecies using DNA probes. Many lab strains are genetic hybrids.
Area of Science:
- Population genetics
- Genomics
- Mammalian Y chromosome evolution
Background:
- Maternal inheritance of mitochondrial DNA (mtDNA) reveals inter-population genetic exchange.
- The mammalian Y chromosome, inherited paternally and with limited recombination, serves as a genomic analogue to mtDNA.
Purpose of the Study:
- To investigate Y chromosome variation in European mouse semispecies (Mus musculus domesticus and Mus musculus musculus).
- To identify distinct Y chromosome types associated with each semispecies.
Main Methods:
- Utilized Y-specific genomic DNA probes from a flow-sorted mouse Y-chromosome library.
- Examined restriction fragment length polymorphisms (RFLPs) in newly established and inbred laboratory mouse lines.
Main Results:
- Identified two variant Y chromosome forms, each specific to one semispecies.
- Found that eight of nine inbred laboratory strains possess a Y chromosome of Mus musculus musculus origin, contrary to previous classifications.
- Strain SJL uniquely carries a Mus musculus domesticus type Y chromosome.
Conclusions:
- The Y chromosome RFLP analysis provides a new method for distinguishing between Mus musculus domesticus and Mus musculus musculus.
- Established inbred laboratory mouse strains, previously considered archetypes, are genetic hybrids between the two semispecies.
- Rethinking the genetic makeup of common laboratory mouse strains is necessary based on Y chromosome data.