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[edit] Summary
| Description |
Spot the Difference: Same Genes but a Different Kink in the Tail. Geneticist Emma Whitelaw (University of Sydney, Australia) studies phenomena in mice similar to those seen in human monozygotic twins, whereby genetically identical individuals can look or behave very differently. About a decade ago, she explains, ‘we noticed that in a litter of mice that had all stably inherited a transgene at a specific locus, some mice expressed the transgene, but others didn't’. This variable gene expressivity in genetically identical animals suggested that some kind of epigenetic mark had occurred differentially between individuals by chance. Similarly, identical mice carrying the agouti viable yellow coat colour gene can range in colour from yellow through mottled to brown, depending on whether the gene is expressed or not. And while a mutation in the axin gene called axin-fused produces mice with kinky tails, the degree of kinkiness varies among genetically identical littermates (Figure). For all these mice, Whitelaw has discovered that the mysterious epigenetic marks responsible for variable expressivity are inherited between sexual generations. So, in the case of the agouti viable yellow mice, yellow mice have more yellow offspring than mottled or brown offspring. Variable expressivity may be a quicker way to deal with environmental change than DNA mutation and, suggests Whitelaw, it may be that variable expressivity is involved in some way in evolution. |
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| Source |
Bradbury J: Human Epigenome Project—Up and Running. PLoS Biol 1/3/2003: e82. http://dx.doi.org/10.1371/journal.pbio.0000082 |
| Date |
Published: December 22, 2003 |
| Author |
(Photograph courtesy of Emma Whitelaw, University of Sydney, Australia.) |
| Permission |
cc-by-2.5 |
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This file is licensed under Creative Commons Attribution 2.5 License In short: you are free to distribute and modify the file as long as you attribute its author(s) or licensor(s). |
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