Rtwq2^LEWES/EiJ
QTL Variant Detail

Summary

• QTL variant: Rtwq2^LEWES/EiJ
• Name: reduced testis weight QTL 2; LEWES/EiJ
• MGI ID: MGI:3829725
• QTL: Rtwq2 Location: unknown Genetic Position: ChrX, Syntenic

Variant origin

• Strain of Specimen: LEWES/EiJ

Variant description

• Allele Type: QTL

Notes

Mapping and Phenotype information for this QTL, its variants and associated markers

J:139578

X-linked genetic loci associated with male sterility were mapped using recombinant consomic strains carrying the proximal (6.8 Mb - 62.3 Mb), central (62.3 Mb - 100.3 Mb) and distal (100.3 Mb - 162.6 Mb) portions of PWK/PhJ-derived X chromosomes on a LEWES/EiJ genetic background for 9 generations. The authors also constructed a reciprocal cross where the same proximal, central and distal portions of LEWES/EiJ-derived X chromosomes were introgressed on a PWK/PhJ genetic background for 7 generations. PWK/PhJ represents X chromosomes from wild strain M. musculus while LEWES/EiJ represents X chromosomes from M. domesticus. Males from hybrid crosses between M. musculus-derived strains and M. domesticus-derived strains tend to display decreased sperm count, smaller testes and abnormal sperm head morphology. Male animals over 70 days of age from the recombinant consomic crosses were phenotyped for testis weight, sperm count, sperm motility, sperm head morphology, seminal vesicle weight and mating success. Multiple loci on the X chromosome appear to affect male fertility traits.

Males from LEWES/EiJ-Chr X^PWK/PhJ recombinant consomic lines displayed severely reduced fertility (n=306 males sampled over 9 backcross generations). The proximal portion of the Xchromosome appears to have the largest effect on testis weight (18.5 cM) and sperm count (15.1 cM). These loci are named Rtwq1 (reduced testis weight QTL 1) which peaks at DXMit141 (LOD=16.52) and Lspcq1 (low sperm count QTL 1) (LOD=10.69), respectively.Rtwq1explains 21.7% of the testis weight variance and Lspcq1 explains 21.9% of the sperm count variance. The 2-LOD confidence interval for Rtwq1 spans 15.1 cM to 25.5 cM while the Lspcq1 interval spans 5.7 cM to 15.5 cM. PWK/PhJ-derived alleles at Rtwq1 and Lspcq1 confer reduced testis weight and decreased sperm count, respectively. Rtwq1 was also detected in the PWK/PhJ-Chr X^LEWES/EiJ recombinant consomic lines. Potential candidate genes for Rtwq1 and Lspcq1 include Ctag2 (20 cM; 61.31 Mb), 4933436I01Rik (25.5 cM; 64.18 Mb) and 1700020N15Rik (26.5 cM; 66.21 Mb). These genes are highly expressed in testis tissue compared to other tissue types.

Linkage to testis weight mapped to distal mouse Chromosome X at 59.5 cM and is named Rtwq2 (reduced testis weight QTL 2). The 2-LOD confidenceinterval spans 50.5 cM to 63.2 cM. This locus explains 6.4% of the phenotypic variance. PWK/PhJ-derived alleles at Rtwq2 confer reduced testis weight. Rtwq2 was identified in both the LEWES/EiJ-Chr X^PWK/PhJ and PWK/PhJ-Chr X^LEWES/EiJ recombinant consomic lines.

The following QTLs were all identified in LEWES/EiJ-Chr X^PWK/PhJ recombinant consomic lines- Abshq1, Abshq2, Abshq3, Abshq4, Abshq5, Abshq6 and Abshq7. PWK/PhJ-derived alleles confer increased incidence of abnormal sperm head morphologyat all QTLs except Abshq5 where PWK/PhJ alleles have the opposite effect. Together, these seven QTL account for 94.4% of the phenotypic variance. The QTLs are additive in nature as males inheriting all seven loci derived from PWK/PhJ display complete sterility.

Abshq1 (abnormal sperm head morphology 1) mapped to 2.5 cM and explains 9.7% of the phenotypic variance. The 2-LOD confidence interval of Abshq1 starts at 0.1 cM but the distal border is undetermined. A previously identified sperm morphology QTL at 8.8 cMnamed Spha1 (sperm head anomaly 1) maps near Abshq1.

Abshq2 (abnormal sperm head QTL 2) maps to 10.3 cM andthe 2-LOD confidence interval spans 7.7 cM to 14.1 cM. This locus explains 23.6% of the phenotypic variance.

Abshq3 (abnormal sperm headQTL 3) maps to 19 cM and the 2-LOD confidence interval spans 18.5 cM to 24.5 cM. This locus explains 26.9% of the phenotypic variance.

Abshq4 (abnormal sperm head QTL 4) maps to 25.5 cM and the 2-LOD confidence interval spans 24.5 cM to 27.5 cM. This locus explains 22.6% of the phenotypic variance. Hstx1 (29.5 cM) and Spha2 (23.8 cM) are previously identified sperm morphology QTL mapping near Abshq4.

Abshq5 (abnormal sperm head QTL 5) maps to 42.7 cM and the 2-LOD confidence interval spans 40.7 cM to 43.6 cM. This locus explains 9.7%% of the phenotypic variance and PWK/PhJ-derived alleles confer decreased incidence of abnormal sperm head morphology.

Abshq6 (abnormal sperm head QTL 6) maps to 49 cM and the 2-LOD confidence interval spans 47.6 cM to 50cM. This locus explains 21.1% of the phenotypic variance.

Abshq7 (abnormal sperm head QTL 7) maps to 73.3 cM. The proximal border of the 2-LOD confidence interval is undetermined. The distal border of the 2-LOD confidence interval at 75.3 cM. This locusexplains 0.2% of the phenotypic variance. Spha3 (sperm head anomaly 3) is a previously identified QTL at 82.3 which is located near Abshq7.

References

• Original: J:139578 Good JM, et al., A complex genetic basis to X-linked hybrid male sterility between two species of house mice. Genetics. 2008 Aug;179(4):2213-28
• All: 1 reference(s)