N. Frankel et al., “Phenotypic robustness conferred by apparently redundant transcriptional enhancers,” Nature, 466:490-93, 2010. Free F1000 Evaluation
Are redundant copies of noncoding DNA sequences due to poor genomic housekeeping, or do they function to improve the organism’s chances of survival? David Stern at Princeton University and colleagues attacked this question by looking at duplicate or “shadow” versions of enhancers, noncoding regions that regulate and promote gene expression. When he knocked out duplicate enhancers for the fruit fly gene shavenbaby, which codes for larval hair growth , he found that the flies were unable to produce hairs in nonoptimal environments, supporting the hypothesis that redundant genetic elements make an organism more robust.
When Stern deleted the duplicate enhancers in drosophila embryos, the larvae grew with a normal number of hairs, suggesting, on first blush,...
The follow up
He decided to test the engineered larvae under more natural conditions, in which temperature can vary up to 10 degrees Celsius in a day. He found flies without duplicate enhancers grew significantly fewer hairs in temperatures at the extremes of normal range, a deficiency that could be repaired by re-expressing the duplicate enhancers.
The bigger picture
The duplicate enhancers “provide robustness against environmental and genetic variation,” writes Faculty Member Miltos Tsiantis in his review.
F1000 evaluators: M. Bulyk (Brigham & Women’s Hosp) • M. Tsiantis (Univ. Oxford)• B. Deplancke (Inst Bioengineering, EPFL)