Epigenetic Effects on Integration of Limb Lengths in a Mouse Model: Selective Breeding for High Voluntary Locomotor Activity |
| |
Authors: | Nathan M Young Benedikt Hallgrímsson Jr" target="_blank">Theodore GarlandJr |
| |
Institution: | (1) Department of Orthopaedic Surgery, University of California San Francisco, San Francisco General Hospital, 1001 Potrero Avenue, San Francisco, CA 94110, USA;(2) Department of Cell Biology and Anatomy, University of Calgary, Health Sciences Centre, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1, Canada;(3) Department of Biology, University of California, Riverside, Riverside, CA 92521, USA |
| |
Abstract: | Mammals exhibit a similar pattern of integration among homologous limb elements, the strength of which is believed to vary
in response to selection for functional coordination or similarity. Although integration is hypothesized to primarily reflect
the effect of genes intrinsic to limbs, extrinsic genetic or epigenetic factors may also affect the strength of integration
through their impact on the magnitude and direction of skeletal variance or covariance. Such factors as neuromuscular coordination
or bone-muscle interactions may therefore play a role in both canalization and the structure or magnitude of limb integration.
If this were the case, then increased levels of locomotor activity would be predicted to increase canalization and the magnitude
of covariation between limbs. To investigate whether postnatal activity levels can have a significant effect on variance within
or covariance among homologous limb elements, we compared four groups of male mice from a long-term selective breeding experiment:
(1) mice from lines bred for increased voluntary activity on running wheels and allowed free access to a wheel for 8 weeks
beginning at weaning (“active”), (2) selected mice that did not have wheel access (“sedentary”), (3) active mice from non-selected
control lines, and (4) sedentary control mice. Mice from selected lines that had wheel access ran significantly more than
control-line mice. However, when controlled for activity, linetype, and body mass, results indicate few significant differences
in means, variance, or covariation structure, and no significant differences in integration between limbs, suggesting that
postnatal activity levels do not significantly affect canalization or integration of limb lengths. A possible explanation
for this result is that whereas baseline levels of postnatal activity may help to maintain patterns of variance and integration,
increased levels of activity do not further increase these measures. Investigations into disrupted epigenetic processes (e.g.,
via models in which neuromuscular coordination is impaired) are required to further test hypotheses about how canalization
or integration of limb variation is affected by epigenetic factors. |
| |
Keywords: | Covariation Experimental evolution Serial homology |
本文献已被 SpringerLink 等数据库收录! |
|