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Titolo:
FITNESS, FLUX AND PHANTOMS IN TEMPORALLY VARIABLE ENVIRONMENTS
Autore:
DEAN AM;
Indirizzi:
UNIV HLTH SCI CHICAGO MED SCH,DEPT BIOL CHEM CHICAGO IL 60064
Titolo Testata:
Genetics
fascicolo: 4, volume: 136, anno: 1994,
pagine: 1481 - 1495
SICI:
0016-6731(1994)136:4<1481:FFAPIT>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
ESCHERICHIA-COLI; SELECTIVE NEUTRALITY; METABOLIC SYSTEMS; NEUROSPORA-CRASSA; NATURAL-SELECTION; ARGININE PATHWAY; ENZYME-REACTIONS; COEFFICIENTS; ADAPTATION; ALLOZYMES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
31
Recensione:
Indirizzi per estratti:
Citazione:
A.M. Dean, "FITNESS, FLUX AND PHANTOMS IN TEMPORALLY VARIABLE ENVIRONMENTS", Genetics, 136(4), 1994, pp. 1481-1495

Abstract

The evolutionary problem of selection in temporally variable environments is addressed by investigating a metabolic model describing the approach to steady state of a flux emanating from a simple linear pathway of unsaturated enzymes catalyzing reversible monomolecular reactions. Analysis confirms previous claims that steps having no influence on the steady state flux may influence transient behavior, and that enzymes immune to natural selection at steady state may become subject to selection when fitness is a function of individual transient metabolic events. Indeed, calculations show that the P-galactosidase of Escherichia coli, which exerts a negligible effect on the steady state lactoseflux, controls the approach to steady state. However, after 6 sec thelactose flux is within O.1% of steady state, and so an ever changing environment must be invoked to continually expose beta-galactosidase to selection. Analysis of the metabolic model undergoing multiple transient events reveals that fitness differences remain unaffected if enzyme activities remain constant and become minimized if enzyme activities differ among environments. Until suitable data become available, claims that metabolic behavior away from steady state necessarily exposesa far greater proportion of allozymes to natural selection should be treated with great skepticism.

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Documento generato il 18/09/20 alle ore 20:11:21