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Jumbled spine and ribs (Jsr): a new mutation on mouse chromosome 5
1Laboratory of Experimental Animal Science, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
Abstract:
Jumbled spine and ribs (Jsr) is an autosomal dominant mutation that results in malformation of the axial skeleton. The vertebrae of mutant mice (Jsr/+) are all shorter than those of normal mice (+/+) in the inbred line and show various abnormalities. In addition, several ribs are fused at their proximal region because of fusion of thoracic vertebrae. In this study, we localized the Jsr mutation on distal Chromosome (Chr) 5 and constructed a high-resolution map. Chromosomal mapping was performed with an inter-subspecific backcross of (CKH-Jsr/+ x MOG) F1 carrying the Jsr allele and CKH-+/+. The predicted gene order around Jsr was determined to be cen-(Epo, Pdgfa, D5Mit31, D5Mit374)-(Jsr, Nfe2u, D5Mit99, D5Mit247, D5Mit284, D5Mit292, D5Mit327)-D5Mit328-tel. Subsequently, high-resolution mapping concluded the Jsr localization to be cen-Nfe2u-1.0cM-Jsr-0.2cM-D5Mit247,292-tel . Jsr/Jsr homozygotes are alive, as the mutation is not lethal. Based on histological analysis of mutant embryos, Jsr is hypothesized to be caused by abnormal development of primordial cells in the axial skeleton.
Insights
The Jumbled spine and ribs (Jsr) mutation causes axial skeleton malformations in mice, including shorter vertebrae and fused ribs. Researchers mapped this autosomal dominant mutation to distal Chromosome 5, pinpointing its location near the Nfe2u gene.
Area of Science:
- Genetics
- Developmental Biology
- Skeletal Biology
Background:
- The Jumbled spine and ribs (Jsr) mutation is an autosomal dominant genetic defect.
- This mutation leads to significant malformations of the axial skeleton in mice.
Purpose of the Study:
- To genetically map the Jsr mutation.
- To construct a high-resolution genetic map for the Jsr locus.
- To understand the developmental basis of the Jsr mutation.
Main Methods:
- Chromosomal mapping using an inter-subspecific backcross.
- Construction of a high-resolution genetic map.
- Histological analysis of mutant embryos.
Main Results:
- The Jsr mutation was localized to distal Chromosome 5.
- A detailed gene order was established: cen-(Epo, Pdgfa, D5Mit31, D5Mit374)-(Jsr, Nfe2u, D5Mit99, D5Mit247, D5Mit284, D5Mit292, D5Mit327)-D5Mit328-tel.
- High-resolution mapping placed Jsr between Nfe2u and D5Mit247,292.
- Jsr/Jsr homozygotes are viable.
Conclusions:
- The Jsr mutation is located on distal Chromosome 5.
- Abnormal development of primordial axial skeleton cells is hypothesized to cause the Jsr phenotype.
- The Jsr mutation provides a model for studying axial skeleton development and malformations.