The recessive misty mutation causes a mild dilution of coat color and on certain backgrounds a white tail tip often accompanied by a belly spot. Melanocytes from m/m mice have a highly dendritic shape, show deficient proliferation in culture and have much more melanin content. Fewer melanoblasts are found in primary cultures from m/m mice than from wildtype controls. Between two and five weeks of age, m/m mice are smaller than controls. At 35 days of age they are shorter, weigh 15% less on average, and have less inguinal adipose mass than controls. Misty homozygotes completely lack brown fat. Although platelet count, seratonin content and ATP content are normal, there is increased bleed time and reduced platelet AD levels in m/m homozygotes. (Woolley, 1941 and 1945; Truett et al., 1998; Sviderskaya et al., 1998.)
The coat color mutation, misty (m), arose spontaneously in a DBA/J colony at The Jackson Laboratory in 1941. The single male was identified by a light color, white tail tip and white belly spot. Misty was introgressed into C57BLKS-Leprdb to create the repulsion stock, BKS.Cg-Dock7m +/+ Leprdb/J. The two alleles were used to identify genotypes in the diabetes colony prior to the use of PCR genotyping. Both mutations then were backcrossed to the C57BL/6 background. In 2008, misty was bred out of the B6.Cg-Dock7m +/+ Leprdb/J colony.
|Gene Symbol and Name||Dock7, dedicator of cytokinesis 7|
|Strain of Origin||DBA/J|
|Molecular Note||Crosses between mice homozygous for misty and for moonlight, which mapped to overlapping critical regions on Chr 4, demonstrated failure of the two mutations to complement one another. Once moonlight had been identified as a mutation of Dock7 (Dock7mnlt), sequence analysis of this gene from misty mice revealed a retrotransposon LTR insertion following nucleotide 2045 (numbering from the A of the transcription initiation codon) that interrupts exon 18 and shifts the reading frame after codon 682 so that ten incorrect amino acids are incorporated into the protein before its premature termination.|
When maintaining a live colony, these mice are bred as homozygotes.
When using the B6.D2(BKS)-Dock7m/J mouse strain in a publication, please cite the originating article(s) and include JAX stock #009659 in your Materials and Methods section.