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Adaptive noise.

Viney M, Reece SE - Proc. Biol. Sci. (2013)

Bottom Line: We argue that such noise can be adaptive.Recent studies have shown that gene expression can be noisy, noise can be genetically controlled, genes and gene networks vary in how noisy they are and noise generates phenotypic differences among genetically identical cells.Such phenotypic differences can have fitness benefits, suggesting that evolution can shape noise and that noise may be adaptive.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK. mark.viney@bristol.ac.uk

ABSTRACT
In biology, noise implies error and disorder and is therefore something which organisms may seek to minimize and mitigate against. We argue that such noise can be adaptive. Recent studies have shown that gene expression can be noisy, noise can be genetically controlled, genes and gene networks vary in how noisy they are and noise generates phenotypic differences among genetically identical cells. Such phenotypic differences can have fitness benefits, suggesting that evolution can shape noise and that noise may be adaptive. For example, gene networks can generate bistable states resulting in phenotypic diversity and switching among individual cells of a genotype, which may be a bet hedging strategy. Here, we review the sources of noise in gene expression, the extent to which noise in biological systems may be adaptive and suggest that applying evolutionary rigour to the study of noise is necessary to fully understand organismal phenotypes.

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The expression of two genes (one red and one blue), among cells of one genotype, where circle size is a measure of expression. (a) Extrinsic noise is where there is similarity of expression of these genes within each cell but differences among the cells. (b) Intrinsic noise is where there is difference in expression of these genes within each cell.
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RSPB20131104F1: The expression of two genes (one red and one blue), among cells of one genotype, where circle size is a measure of expression. (a) Extrinsic noise is where there is similarity of expression of these genes within each cell but differences among the cells. (b) Intrinsic noise is where there is difference in expression of these genes within each cell.

Mentions: For any gene, the quantity of protein it produces can vary among cells: this is called noise, measured as the coefficient of variation of the quantity of protein (box 1). Noise can be extrinsic or intrinsic. Extrinsic noise is that which is common to genes of any one cell, due to differences between cells, such as energy state, or concentration of regulatory molecules, etc. [7]. Intrinsic noise is that which is specific to any one gene, for example because of transcriptional and translation effects. By examining cells containing two reporter genes, where the reporter genes' products can be distinguished [4,7,8], these types of noise are manifest; extrinsic noise is the similarity of expression of these genes within a cell, but there may be differences among cells; intrinsic noise is differences in expression between these two genes within a cell (figure 1 and box 1). For example, in Escherichia coli both extrinsic and intrinsic noise make a substantial contribution to among-cell heterogeneity; intrinsic noise is greater at low transcription rates (consistent with earlier ideas about low molecular concentrations [9]), and a cell's genetic background also affects the amplitude of noise [4]. Similar findings have also been made in eukaryotes [8,10]; indeed, it now appears that noise is common among diverse systems—it is likely to be a universal feature of life [9].Box 1.Glossary.


Adaptive noise.

Viney M, Reece SE - Proc. Biol. Sci. (2013)

The expression of two genes (one red and one blue), among cells of one genotype, where circle size is a measure of expression. (a) Extrinsic noise is where there is similarity of expression of these genes within each cell but differences among the cells. (b) Intrinsic noise is where there is difference in expression of these genes within each cell.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3735249&req=5

RSPB20131104F1: The expression of two genes (one red and one blue), among cells of one genotype, where circle size is a measure of expression. (a) Extrinsic noise is where there is similarity of expression of these genes within each cell but differences among the cells. (b) Intrinsic noise is where there is difference in expression of these genes within each cell.
Mentions: For any gene, the quantity of protein it produces can vary among cells: this is called noise, measured as the coefficient of variation of the quantity of protein (box 1). Noise can be extrinsic or intrinsic. Extrinsic noise is that which is common to genes of any one cell, due to differences between cells, such as energy state, or concentration of regulatory molecules, etc. [7]. Intrinsic noise is that which is specific to any one gene, for example because of transcriptional and translation effects. By examining cells containing two reporter genes, where the reporter genes' products can be distinguished [4,7,8], these types of noise are manifest; extrinsic noise is the similarity of expression of these genes within a cell, but there may be differences among cells; intrinsic noise is differences in expression between these two genes within a cell (figure 1 and box 1). For example, in Escherichia coli both extrinsic and intrinsic noise make a substantial contribution to among-cell heterogeneity; intrinsic noise is greater at low transcription rates (consistent with earlier ideas about low molecular concentrations [9]), and a cell's genetic background also affects the amplitude of noise [4]. Similar findings have also been made in eukaryotes [8,10]; indeed, it now appears that noise is common among diverse systems—it is likely to be a universal feature of life [9].Box 1.Glossary.

Bottom Line: We argue that such noise can be adaptive.Recent studies have shown that gene expression can be noisy, noise can be genetically controlled, genes and gene networks vary in how noisy they are and noise generates phenotypic differences among genetically identical cells.Such phenotypic differences can have fitness benefits, suggesting that evolution can shape noise and that noise may be adaptive.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK. mark.viney@bristol.ac.uk

ABSTRACT
In biology, noise implies error and disorder and is therefore something which organisms may seek to minimize and mitigate against. We argue that such noise can be adaptive. Recent studies have shown that gene expression can be noisy, noise can be genetically controlled, genes and gene networks vary in how noisy they are and noise generates phenotypic differences among genetically identical cells. Such phenotypic differences can have fitness benefits, suggesting that evolution can shape noise and that noise may be adaptive. For example, gene networks can generate bistable states resulting in phenotypic diversity and switching among individual cells of a genotype, which may be a bet hedging strategy. Here, we review the sources of noise in gene expression, the extent to which noise in biological systems may be adaptive and suggest that applying evolutionary rigour to the study of noise is necessary to fully understand organismal phenotypes.

Show MeSH
Related in: MedlinePlus