Spha2^C57BL/6J
QTL Variant Detail

Summary

• QTL variant: Spha2^C57BL/6J
• Name: sperm head anomaly 2; C57BL/6J
• MGI ID: MGI:3040372
• QTL: Spha2 Location: ChrX:39921498-86260137 bp Genetic Position: ChrX, Syntenic

Variant origin

• Strain of Specimen: C57BL/6J

Variant description

• Allele Type: QTL

Notes

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

J:88875

Genetic factors of hybrid breakdown were studied using a consomic strain carrying an entire X chromosome derived from MSM/Ms on a C57BL/6J background (C57BL/6J-X^MSM). Donor strain MSM/Ms and recipient strain C57BL/6J diverged from a common ancestor approximately 1 million years ago. Cross breeding of these two inbred strains results in reduced fertility several generations later. Males of consomic strain C57BL/6J-X^MSM are sterile and exhibit reduced testis weight and sperm head malformations. Markers on the X chromosome were typed in recombinant and non-recombinant animals from the N2-N7 backcross generations for linkage to these traits.

Significant linkage to reduced testis weight mapped to distal chromosome X with maximum linkage (LRS=110.7) between DXMit4 (58 cM) and DXMit217 (63 cM). This locus is designated Tswt (testis weight). The QTL interval of Tswt spans 49 cM (DXMit97) - 70.5 cM (DXMit249). This locus accounts for 78% of the phenotypic variance. The reduced testis weight phenotype was recapitulated in a congenic strain carrying an MSM/Ms-derived portion of chromosome X from 49 cM (DXMit97) - 73.3 cM (DXMit160) on a C57BL/6J background, thus confirming the effect of this locus. However, males of the congenic strain are fertile and produce litters of normal size.

Linkage to abnormal sperm head morphology mapped to three peaks on chromosome X. The most proximal peak mapped to 8.8 cM (LRS=59) and is named Spha1 (sperm head anomaly 1). The QTL interval of Spha1 is flanked by markers DXMit89(3 cM) and DXMit50 (14.1 cM). Spha2 mapped to an interval between 14.1 cM (DXMit50) - 33.5 cM (DXMit147) with LRS=110.1. This QTL maps near a previously identified QTL named Shx1. Potential candidate genes mapping near Spha2 include Tsga8 (Halapx), Nr0b1, Fmr1, and Sox3. Spha3 mapped to an interval between DXMit95 (43 cM) and DXMit249 (70.5 cM) with LRS=82.3.

References

• Original: J:88875 Oka A, et al., Hybrid breakdown caused by substitution of the X chromosome between two mouse subspecies. Genetics. 2004 Feb;166(2):913-24
• All: 1 reference(s)