129S6.Cg-Sfxn1^m1Mdf/Mmjax

Stock number: 018453
Product name: flexed tail

Description

It has not been conclusively determined if f is an allele of Sfxn1, for this reason we have renamed the allele identified by Dr. Fleming from f to Sfxn1^m1Mdf. The strain currently exhibits a flexed tail phenotype; it is not known if the phenotypic flexed tail will be eliminated when the colony is maintained by genotype rather than phenotype.

Detailed description

NOTE: It has not been conclusively determined if f is an allele of Sfxn1, for this reason we have renamed the allele identified by Dr. Fleming from f to Sfxn1^m1Mdf. The strain currently exhibits a flexed tail phenotype; it is not known if the phenotypic flexed tail will be eliminated when the colony is maintained by genotype rather than phenotype.

That said -- the following describes the flexed tail phenotype --- Mice homozygous for the flexed-tail (f) allele can be identified hematologically as early as embryonic day 13 and are detectably paler than normal by embryonic day 16. Homozygotes are small at birth and have a transitory siderocytic hypochromic anemia due to defective heme synthesis in fetal, but not adult reticulocytes. Most homozygotes have a belly spot and 1 to 5 flexures in the tail due to vertebral fusions. Vertebral fusions are also found elsewhere in the vertebral column. Fewer than expected homozygotes are generated indicating that the prenatal death and the postnatal death rate is approximately 4 times normal. A small minority of homozygotes have been found to have embryonic neural tube defects or a dorsal enlargement of the head.

Development

NOTE: It has not been conclusively determined if f is an allele of Sfxn1, for this reason we have renamed the allele identified by Dr. Fleming from f to Sfxn1^m1Mdf. The strain currently exhibits a flexed tail phenotype; it is not known if the phenotypic flexed tail will be eliminated when the colony is maintained by genotype rather than phenotype.

The flexed tail (f) mutation arose spontaneously on an undefined mouse stock in the laboratory of Dr. Harrison Hunt at Michigan State College in 1927. The strain has been introgressed into multiple backgrounds including FL/1ReJ, JE/LeJ, and WB. Mapping work done by Dr. Mark Fleming suggests that f is a single base insertion (adenine) in exon 2 of the sideroflexin 1 (Sfxn1) gene, which results in a truncated peptide. Western blot analysis indicates that protein is absent. Concurrently, another group has identified f as a mutation in Smad5. Dr Fleming at Harvard Medical College backcrossed the Sfxn1^m1Mdf allele to 129S6/SvEvTac for a minimum of 19 generations.

Allele

Symbol: Sfxn1^m1Mdf
Name: mutation 1, Mark Fleming
MGI accession ID: MGI:5468013
Generation method: Spontaneous
Marker symbol: Sfxn1
Marker name: sideroflexin 1
Chromosome: 13
Strain of origin: Not Specified
Molecular note: An insertion of a single A residue after codon 15 of the reading frame. This mutation is predicted to result in a truncated protein consisting of the first 15 amino acids followed by 17 novel amino acids before an in-frame stop codon.
General note: This allele is on of two suggested as responsible for the flexed tail mutation (f). J:128616 suggests that a Smad5 splicing defect (mutation in a polyT element in intron 4) may be causative of flexed tail.