Mice homozygous for Ces1ce are viable and fertile and exhibit no apparent defect.
Ces1ce was discovered in a screen of progeny of triethylenemelamine (TEM) treated male mice for mutations at specific loci, but appears to have pre-existed in the male. The screen employed analysis of blood and kidney homogenates by "standard starch gel electrophoresis techniques" and focused on enzymes known to differ in electrophoretic mobility between the parental strains (DBA/2J and C57BL/6J). Ces1ce was initially thought to be a null allele, but characterization of homozygous F2 mice demonstrated presence of a faint band migrating between those of the parental strains, which was not perceived in the presence of either parental band. Thus, Ces1ce was shown to be a hypomorphic electrophoretic variant (Soares 1979).
Ces1ce was discovered in a specific-locus mutation screen of progeny of triethylenemelamine (TEM) mutagenized male DBA/2J mice, but appears to have been a pre-existing, spontaneous mutation. Although the TEM-treated parent was unavailable for genotyping, three lines of evidence suggest he was a heterozygous carrier of the mutation: 7 of 13 (54%) of his immediate offspring were heterozygous for Ces1ce; he was mated within 2 weeks after TEM treatment, so these progeny were generated from sperm that were either sperm or late spermatids when exposed, ruling out a clustering effect due to mutagenesis at the spermatogonial stage; and the seven Ces1ce/+ offspring occurred among litters of three dams (Soares 1979).
Mice of a strain/stock bearing Ces1ce, called ES-IE, were imported from Dr. Soares, then at NIEH, by Dr. Eva Eicher in 1979. The original stock was maintained by sister-brother inbreeding. In 1982, Ces1ce/Ces1ce males of this stock were bred to C57BL/6J females to produce embryos for cryopreservation. These heterozygous embryos were assigned Stock No. 000785.
|Gene Symbol and Name||a, nonagouti|
|Strain of Origin||old mutant of the mouse fancy|
|General Note||Insertion of the LV30 retrotransposon without the beta4 retrovirus sequence does not cause the nonagouti phenotype. J:278039|
|Molecular Note||Characterization of this allele shows an insertion of DNA comprised of a 5.5kb virus-like element, VL30, into the first intron of the agouti gene. The VL30 element itself contains an additional 5.5 kb sequence, flanked by 526 bp of direct repeats (beta4 retroviral sequence). The host integration site is the same as for at-2Gso and Aw-38J and includes a duplication of four nucleotides of host DNA and a deletion of 2 bp from the end of each repeat. Northern analysis of mRNA from skin of homozygotes shows a smaller agouti message and levels 8 fold lower than found in wild-type.|