Mice homozygous for the dense incisors mutation have normal initial eruption of incisors through the gingiva, but further eruption is arrested. As a result continued dentin formation gradually occludes the pulp chambers resulting in dense teeth and an anterior open bite. The molars erupt normally. Homozygotes also have a smaller than normal body size, smaller than normal ear pinna, and pigment dilution that is more pronounced in the ventral fur than the dorsal fur and causes white feet and a white tail tip. The white feet and tail tip are not distinguishing features of this mutation, rather the lack of incisor eruption at 10 days of age, small ear pinnae, and dilution of the ventral fur pigment at 20 days of age are distinguishing features on this background. Most homozygotes die before 5 months of age, and this is not altered by the addition of powdered food to the bottom of the cage. Homozygotes are not successful breeders and although female homozygotes have become pregnant they have failed to deliver. When outcrossed to CAST/EiJ and intercrossed the homozygotes have a more variable phenotype, with half displaying lower incisors at 10 days of age despite having the proportionate dwarf and diluted ventral coat color phenotypes. The diluted ventral coat color is more severe in the segregating CAST/EiJ background.
The dense incisors mutation (din) arose spontaneously in strain C3H/HeJ at F181 in 1984 at the Jackson Laboratory. It was sibling mated and ovaries from a homozygous female were transplanted into a B6C3Fe-a/a F1 host and mated to a C57BL/6J male. The offspring were sibling mated and an ovary transplant was made in the next generation and crossed to the B6C3Fe-a/a hybrid. The mutation was maintained on this hybrid background using the cross intercross system with ovary transplantation. It was cryopreserved in 1992 by mating din/+ males to din/+ females at N19.
|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.|
|Allele Name||dense incisors|
|Gene Symbol and Name||4930453N24Rik, RIKEN cDNA 4930453N24 gene|
|Strain of Origin||C3H/HeJ|
|Molecular Note||A T-to-A point mutation at postition 729 of the cDNA (NM_026273) results in premature truncation at position 243 of the encoded protein (p.C243*).|
When using the dense incisors mouse strain in a publication, please cite the originating article(s) and include JAX stock #002018 in your Materials and Methods section.