Segregation distortion of X-linked marker genes in interspecific crosses between Mus musculus and M. spretus

Area of Science:

• Genetics
• Evolutionary Biology
• Mammalian Reproduction

Background:

• Interspecific hybridization can lead to reproductive incompatibilities.
• Understanding genetic interactions between species is crucial for evolutionary studies.
• The mouse species Mus musculus and Mus spretus are commonly used models for genetic research.

Purpose of the Study:

• To investigate the genetic basis of hybrid sterility/viability in crosses between Mus musculus and Mus spretus.
• To identify specific chromosomal interactions causing deleterious effects in hybrid offspring.
• To determine the role of X and Y chromosomes in interspecific reproductive isolation.

Main Methods:

• An interspecific cross was performed between C3H/HeHa.Pgk-1 a (Mus musculus) females and Mus spretus males.
• F1 generation females were backcrossed to both C3H and spretus males.
• Segregation of X-linked marker genes was analyzed in backcross progeny.

Main Results:

• F1 males from the interspecific cross were sterile.
• F1 females were fertile and produced offspring in backcrosses.
• A male-lethal effect was observed when the interspecific F1 female's X chromosome was combined with the Mus spretus Y chromosome, but not the Mus musculus Y chromosome.
• Segregation data indicated a genetically deleterious effect on the C3H X chromosome.

Conclusions:

• The X chromosome of Mus musculus carries genetic factors that are detrimental when combined with the Y chromosome of Mus spretus.
• This finding highlights a specific mechanism of reproductive isolation between closely related mouse species.
• The Y chromosome of Mus spretus appears to be a key factor in the observed male lethality in hybrids.