NYU Biologists Identify Genes That Prevent Changes In Physical Traits Due To Environmental Changes

Main Category: Genetics
Also Included In: Biology / Biochemistry
Article Date: 05 Nov 2008 - 1:00 PST

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In this week's PLoS Biology, authors Mark Siegal and Sasha Levy identify genes that prevent physical traits from being affected by environmental changes. The paper seeks to answer the contradiction: "If biological systems are so resistant to variation, how do they diverge and adapt through evolutionary time?" Although phenotypic, or physical, differences between individuals are usually small, most species maintain abundant genetic variation and experience a wide range of environmental conditions.

To understand the genes that buffer environmental and genetic variation, which may influence how novel traits evolve, the researchers examined Saccharomyces cerevisiae, a species of budding yeast. They investigated the molecular mechanisms that underlie its phenotypic robustness and how these mechanisms can be broken to produce differences in physical appearance within the species.

Siegal and Levy sought to identify genes that contribute to phenotypic robustness in yeast by analyzing their phenotypes in single-gene knockout strains - that is, they removed these genes to determine if the resulting phenotypes were different from cell to cell.

They determined that approximately 5 percent of yeast genes, or approximately 300 genes, break phenotypic robustness when knocked out. These genes tend to interact genetically with a large number of other genes, and their products tend to interact physically with a large number of other gene products. When they are absent, the cellular networks built from their interactions are disrupted and physical differences in the species result. In nature, the researchers hypothesized, some individuals might then have physical features that yield an advantage over the others. The loss of phenotypic robustness caused by mutation of one of these genes might thereby serve an adaptive role during evolution.

"Network hubs buffer environmental variation in Saccharomyces cerevisiae."
Levy SF, Siegal ML (2008)
PLoS Biol 6(11): e264. doi:10.1371/journal.pbio.0060264
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PLoS Biology

PLoS Biology (eISSN-1545-7885; ISSN-1544-9173) is an open-access, peer-reviewed general biology journal published by the Public Library of Science (PLoS), a nonprofit organization of scientists and physicians committed to making the world's scientific and medical literature a public resource. New articles are published online weekly; issues are published monthly.

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