Mice that are homozygous for this targeted mutation, when kept in constant darkness, exhibit a shorter circadian period than wild-type controls. This mutant mouse strain may be useful in studies of circadian rhythm and behavior.
David R. Weaver, Univ of Massachusetts Medical School
Mice that are homozygous for the targeted mutation are viable, fertile, normal in size and do not display any gross physical or behavioral abnormalities. No gene product (protein) is detected by immunohistochemical and immunoprecipitation analysis of SCN (suprachiasma nucleus). Homozygotes exhibit a shorter circadian period of approximately 20 minutes, when kept in constant darkness. While under 12 hr light/12 hr dark (LD) cycle, homozygotes become active approximately 2 hours before the start of the dark cycle, indicating altered response to light cues. A four hour extended light period preceding constant darkness does not result in the expected activity rhythm phase delay. Re-entrainment with LD cycle followed by a 4 hour light pulse in the dark cycle does not cause activity rhythm phase advance.
A loxP site flanked targeting vector containing neomycin resistance and thymidine kinase genes was utilized in the construction of this mutant. This selection cassette was inserted upstream of exon 5 of the targeted gene, and another loxP site was inserted downstream of exon 6. This construct was electroporated into 129S4/SvJae derived J1 embryonic stem (ES) cells which were transiently transfected with a Cre recombinase vector to remove the selection cassette. Correctly targeted ES cells were injected into C57BL/6J blastocysts. The resulting chimeric animals were crossed to C57BL/6J mice, and then crossed to transgenic mice expressing Cre recombinase in the male germ line, to remove the floxed exons (Protamine-cre, on the C57BL6J background). Mice that no longer contained exons 5-6 or the Cre recombinase transgene were backcrossed to C57BL/6J for 10 generations. Upon arrival at The Jackson Laboratory, the mice were crossed with C57BL/6J once to establish the colony.
|Allele Name||targeted mutation 1.1, Steven M Reppert|
|Allele Type||Targeted (Null/Knockout)|
|Allele Synonym(s)||Clockdelta5-6; Clocktm1.1Drw|
|Gene Symbol and Name||Clock, circadian locomotor output cycles kaput|
|Strain of Origin||129S4/SvJae|
|Molecular Note||Cre mediated recombination resulted in the excision of exons 5 and 6. Immunohistochemistry confirmed absence of protein in mutants.|
|Mutations Made By|| |
Steven Reppert, University of Massachusetts Medical Scho
When maintaining a live colony, these mice can be bred as homozygotes.
When using the B6.129S4-Clocktm1.1Rep/J mouse strain in a publication, please cite the originating article(s) and include JAX stock #010925 in your Materials and Methods section.