title: Genomic GC level, optimal growth temperature, and genome size in prokaryotes.
abstract: Two years ago, we showed that positive correlations between optimal growth temperature (T(opt)) and genome GC are observed in 15 out of the 20 families of prokaryotes we analyzed, thus indicating that "T(opt) is one of the factors that influence genomic GC in prokaryotes". Our results were disputed, but these criticisms were demonstrated to be mistaken and based on misconceptions. In a recent report, Wang et al. [H.C. Wang, E. Susko, A.J. Roger, On the correlation between genomic G+C content and optimal growth temperature in prokaryotes: data quality and confounding factors, Biochem. Biophys. Res. Commun. 342 (2006) 681-684] criticize our results by stating that "all previous simple correlation analyses of GC versus temperature have ignored the fact that genomic GC content is influenced by multiple factors including both intrinsic mutational bias and extrinsic environmental factors". This statement, besides being erroneous, is surprising because it applies in fact not to ours but to the authors' article. Here, we rebut the points raised by Wang et al. and review some issues that have been a matter of debate, regarding the influence of environmental factors upon GC content in prokaryotes. Furthermore, we demonstrate that the relationship that exists between genome size and GC level is valid for aerobic, facultative, and microaerophilic species, but not for anaerobic prokaryotes.
authors.affiliation: Laboratorio de Organización y Evolución del Genoma, Facultad de Ciencias, Montevideo, Uruguay.
authors.forename: Héctor
authors.initials: H
authors.lastname: Musto
authors.forename: Hugo
authors.initials: H
authors.lastname: Naya
authors.forename: Alejandro
authors.initials: A
authors.lastname: Zavala
authors.forename: Héctor
authors.initials: H
authors.lastname: Romero
authors.forename: Fernando
authors.initials: F
authors.lastname: Alvarez-Valín
authors.forename: Giorgio
authors.initials: G
authors.lastname: Bernardi
mesh_terms: D001482:Base Composition / Q000235:genetics*; D004755:Enterobacteriaceae / Q000235:genetics* / Q000254:growth & development*; D016680:Genome, Bacterial / Q000235:genetics*; D008957:Models, Genetic; D011387:Prokaryotic Cells / Q000502:physiology*; D013696:Temperature