Abstract
BackgroundTransmission ratio distortion (TRD), defined as statistically significant deviation from expected 1:1 Mendelian ratios of allele inheritance, results in a reduction of the expected progeny of a given genotype. Since TRD is a common occurrence within interspecific crosses, a mouse interspecific backcross was used to genetically map regions showing TRD, and a developmental analysis was performed to identify the timing of allele loss.ResultsThree independent events of statistically significant deviation from the expected 50:50 Mendelian inheritance ratios were observed in an interspecific backcross between the Mus musculus A/J and the Mus spretus SPRET/EiJ inbred strains. At weaning M. musculus alleles are preferentially inherited on Chromosome (Chr) 7, while M. spretus alleles are preferentially inherited on Chrs 10 and 11. Furthermore, alleles on Chr 3 modify the TRD on Chr 11. All TRD loci detected at weaning were present in Mendelian ratios at mid-gestation and at birth.ConclusionsGiven that Mendelian ratios of inheritance are observed for Chr 7, 10 and 11 during development and at birth, the underlying causes for the interspecific TRD events are the differential post-natal survival of pups with specific genotypes. These results are consistent with the TRD mechanism being deviation from Mendelian inheritance rather than meiotic drive or segregation distortion.
Highlights
Transmission ratio distortion (TRD), defined as statistically significant deviation from expected 1:1 Mendelian ratios of allele inheritance, results in a reduction of the expected progeny of a given genotype
Given that Mendelian ratios of inheritance are observed for Chr 7, 10 and 11 during development and at birth, the underlying causes for the interspecific TRD events are the differential post-natal survival of pups with specific genotypes
These results are consistent with the TRD mechanism being deviation from Mendelian inheritance rather than meiotic drive or segregation distortion
Summary
Transmission ratio distortion (TRD), defined as statistically significant deviation from expected 1:1 Mendelian ratios of allele inheritance, results in a reduction of the expected progeny of a given genotype. Used inbred mouse strains, which trace their genetic ancestry primarily to the Mus musculus domesticus subspecies [1], have extensive interspecific polymorphic differences when compared to Mus spretus. Interspecific backcrosses often result in skewed distributions in the inheritance of polymorphic alleles from the hybrid females, a phenomenon called transmission ratio distortion (TRD) [3,4,5,6,7,8]. Transmission ratio distortion is defined as statistically significant deviation from the expected 1:1 Mendelian ratios of allele inheritance, resulting in a reduction of the expected progeny of a given genotype. Transmission ratio distortion has been observed in wild M. musculus populations involving Chr 1 and in commonly derived inbred strains on Chr 11 [12,13,14,15]
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