Another effect of randomness in gene expression might be observed, for example, in cells with two slightly different copies of the same gene, where one might be noisier than the other. Such noise might also produce variability among cells that might offer evolutionary advantages.
Noise in genes might also be a trigger for the formation of tumors, said O'Shea. In cases where cells lose one copy of a gene through mutation, the reduction in gene number increases the noise in gene expression. This increase in noise makes it more likely that the remaining gene might alter its activity to trigger uncontrolled proliferation.
Noise could be necessary for normal development of some biological systems, said O'Shea. For example, when olfactory neurons in the developing embryo are "deciding" which of a multitude of possible odorant receptors they will produce -- a choice that is final -- random noise in gene expression might be necessary to enable this decision, she said.
O'Shea said that her group plans to continue this line of research and hopes to identify in which such randomness is beneficial to an organism. Then, they will alter the level of noise and determine how it affects the fitness of the organism. They also want to follow noise production in a single cell over time -- rather than in populations of cells -- to explore in more detail how noise is produced.
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Contact: Jim Keeley
keeleyj@hhmi.org
301-215-8858
Howard Hughes Medical Institute
27-May-2004