The information encoded in the DNA of an organism is not sufficient to determine the expression pattern of genes. This fact was known even before the discovery of epigenetics, which refers to external modifications to the DNA that turn genes "on" or "off." These modifications do not change the DNA sequence, but instead, they affect how genes are expressed. Another, less known mechanism called “canalization” (http://en.wikipedia.org/wiki/Canalisation_%28genetics%29) keeps organisms robust despite genetic mutations and environmental stressors. If an organism experiences environmental or genetic perturbations during its development, such as extreme living conditions or genetic mutations, canalization acts as a way of buffering these disturbances. The organism remains stable and can continue to develop without recognizable changes. The article, entitled “Temperature Stress Mediates Decanalization and Dominance of Gene Expression in Drosophila melanogaster,” was published on February 26, 2015 in the open-access journal PLOS Genetics. Dr. Christian Schlötterer, at the Institute of Population Genetics, The University of Veterinary Medicine, Vienna, in Austria, together with colleagues, studied the mechanism of canalization in fruit flies. The researchers subjected two genetically distinct strains of fruit flies, Oregon and Samarkand, to different temperatures (13°C, 18°C, 23°C, and 29°C). Subsequently, the scientists analyzed the variation in gene expression in response to the different temperatures. The results revealed a homogeneous pattern of gene expression among the two strains at 18°C. No matter whether the flies were from the Oregon or to the Samarkand strain, their gene expression was almost indistinguishable.
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