iansmith
May28-04, 05:31 PM
By Cathy Holding
The random fluctuations—also known as noise—of gene expression could account for phenotypic variations ranging from the minor—such as different fingerprints in identical twins—to the major, including normal embryonic development, according to a study in the May 27 Science.
The authors, Erin K. O'Shea and Jonathan M. Raser at the Howard Hughes Medical Institute, University of California at San Francisco, say their measurements of noise in single budding yeast cells suggest that noise also provides a means, albeit temporary, of cellular adaptation to the environment.
O'Shea and Raser cloned two—cyan and yellow—fluorescent protein reporter genes under the control of identical budding yeast PHO5 gene promoters to look at cell-to-cell differences in a population of yeast cells. When all cells express similar quantities of the fluorescent proteins at similar times, then little variability—meaning little randomness—in gene expression is occurring, Raser said.
"If we see substantial differences between two independent but identical genes—if the yellow fluorescent protein appears 30 minutes before the cyan appears [in one cell but not in another]—then we can say that's due to randomness, because the cell can't tell the two proteins apart at all," Raser, co-author of the paper, told The Scientist.
Raser said that noise contributes to variability at the population level. "Noisy genes will have highly variable expression at the population level, and genes that are much less noisy will be very consistent at the population level," he said.
http://www.biomedcentral.com/news/20040528/01
The random fluctuations—also known as noise—of gene expression could account for phenotypic variations ranging from the minor—such as different fingerprints in identical twins—to the major, including normal embryonic development, according to a study in the May 27 Science.
The authors, Erin K. O'Shea and Jonathan M. Raser at the Howard Hughes Medical Institute, University of California at San Francisco, say their measurements of noise in single budding yeast cells suggest that noise also provides a means, albeit temporary, of cellular adaptation to the environment.
O'Shea and Raser cloned two—cyan and yellow—fluorescent protein reporter genes under the control of identical budding yeast PHO5 gene promoters to look at cell-to-cell differences in a population of yeast cells. When all cells express similar quantities of the fluorescent proteins at similar times, then little variability—meaning little randomness—in gene expression is occurring, Raser said.
"If we see substantial differences between two independent but identical genes—if the yellow fluorescent protein appears 30 minutes before the cyan appears [in one cell but not in another]—then we can say that's due to randomness, because the cell can't tell the two proteins apart at all," Raser, co-author of the paper, told The Scientist.
Raser said that noise contributes to variability at the population level. "Noisy genes will have highly variable expression at the population level, and genes that are much less noisy will be very consistent at the population level," he said.
http://www.biomedcentral.com/news/20040528/01