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Phenotypic characterization of the transgenic mouse insertional mutation, legless.
J D McNeish1, J Thayer, K Walling
1Graduate Program in Developmental Biology, University of Cincinnati, Ohio.
The Journal of Experimental Zoology
|February 1, 1990
Summary
The legless mutation causes severe congenital malformations in mice, including limb loss, craniofacial defects, and organ transposition. This transgenic model aids in understanding gene function and developmental abnormalities.
Area of Science:
- Developmental biology
- Genetics
- Teratology
Background:
- Transgenic insertional mutations offer valuable tools for studying gene function.
- The legless mutation presents a unique autosomal recessive, perinatally lethal phenotype.
Purpose of the Study:
- To comprehensively characterize the dysmorphologic phenotype of the legless mutation.
- To compare the malformations in homozygous mutants with wild-type and heterozygous siblings.
- To identify potential gene functions disrupted by this insertional mutation.
Main Methods:
- Detailed skeletal, craniofacial, and visceral analyses of homozygous legless mutants.
- Comparative examination with wild-type nontransgenic and heterozygous littermates.
- Brain examination to assess anterior structure development.
Main Results:
- Consistent loss of distal limb structures (hindlimbs and preaxial forelimbs).
- Variable craniofacial malformations, including cleft lip and palate, ranging to severe midline clefts with encephaloceles.
- Significant defects in anterior brain structures (olfactory lobes, cerebrum) in over 90% of mutants.
- Visceral transposition (thoracic/abdominal organs) observed in approximately 50% of mutants.
Conclusions:
- The legless mutation induces a pleiotropic array of congenital malformations.
- The transgene serves as a tag for molecular identification of the disrupted gene.
- Understanding this phenotype aids in elucidating the function of the affected genetic locus.