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Reproductive performance in female Clock Delta19 mutant mice
David J Kennaway1, Michael J Boden, Athena Voultsios
1Department of Obstetrics and Gynaecology, University of Adelaide, Medical School, Adelaide, SA, Australia. david.kennaway@adelaide.edu.au
Reproduction, Fertility, and Development
|March 3, 2005
Summary
Disrupted clock gene function in mice impacts reproductive performance, causing delays in mating and smaller litters. Melatonin restoration partially mitigates these effects, showing circadian system redundancy.
Area of Science:
- Chronobiology
- Reproductive Biology
- Genetics
Background:
- Circadian rhythmicity is linked to rodent reproductive cycles.
- The specific impact of disrupted clock gene function on reproduction remains unclear.
- The Clock(Delta19) mutation affects circadian rhythmicity.
Purpose of the Study:
- To evaluate the reproductive performance of mice with the Clock(Delta19) mutation.
- To assess the influence of melatonin deficiency versus melatonin synthesis capacity on reproduction in these mutants.
- To investigate the role of circadian gene redundancy in maintaining reproductive cyclicity.
Main Methods:
- Comparison of reproductive parameters (mating time, delivery time, litter size, survival) between Clock(Delta19) mutant mice (melatonin deficient and melatonin competent) and control lines.
- Assessment of behavioral rhythmicity in constant darkness.
- Evaluation of pregnancy success in arrhythmic and free-running mutant mice.
Main Results:
- Clock(Delta19/Delta19) mice showed delays in mating and delivery (2-3 days) and reduced litter size (7 vs. 8 pups) compared to controls.
- Melatonin competence partially reversed the delay and normalized litter size.
- Despite behavioral arrhythmicity in constant darkness, mutant mice successfully became pregnant, indicating reproductive function persistence.
Conclusions:
- The Clock(Delta19) mutation has subtle but significant negative effects on mouse reproductive performance.
- Melatonin reintroduction and genetic background (e.g., CBA crosses) can reduce the mutation's impact.
- Redundancy within the circadian system allows for the continuation of reproductive cyclicity, even if suboptimal.