title: On the genome base composition of teleosts: the effect of environment and lifestyle.
abstract: BACKGROUND
  The DNA base composition is well known to be highly variable among organisms. Bio-physic studies on the effect of the GC increments on the DNA structure have shown that GC-richer DNA sequences are more bendable. The result was the keystone of the hypothesis proposing the metabolic rate as the major force driving the GC content variability, since an increased resistance to the torsion stress is mainly required during the transcription process to avoid DNA breakage. Hence, the aim of the present work is to test if both salinity and migration, suggested to affect the metabolic rate of teleostean fishes, affect the average genomic GC content as well. Moreover, since the gill surface has been reported to be a major morphological expression of metabolic rate, this parameter was also analyzed in the light of the above hypothesis.
  
  
  RESULTS
  Teleosts living in different environments (freshwater and seawater) and with different lifestyles (migratory and non-migratory) were analyzed studying three variables: routine metabolic rate, gill area and genomic GC-content, none of them showing a phylogenetic signal among fish species. Routine metabolic rate, specific gill area and average genomic GC were higher in seawater than freshwater species. The same trend was observed comparing migratory versus non-migratory species. Crossing salinity and lifestyle, the active migratory species living in seawater show coincidentally the highest routine metabolic rate, the highest specific gill area and the highest average genomic GC content.
  
  
  CONCLUSIONS
  The results clearly highlight that environmental factors (salinity) and lifestyle (migration) affect not only the physiology (i.e. the routine metabolic rate), and the morphology (i.e. gill area) of teleosts, but also basic genome feature (i.e. the GC content), thus opening to an interesting liaison among the three variables in the light of the metabolic rate hypothesis.
authors.affiliation: Genome Evolution and Organization - Department BEOM, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Naples, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Tarallo
authors.affiliation: Istituto per le Applicazioni del Calcolo "Mauro Picone" - CNR, Via Pietro Castellino, 111, 80131, Naples, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Angelini
authors.affiliation: Genome Evolution and Organization - Department BEOM, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Naples, Italy.
authors.forename: Remo
authors.initials: R
authors.lastname: Sanges
authors.affiliation: Faculty of Fisheries, Nagasaki University, 1-14 Bunkyo, Nagasaki, 852-8521, Japan.
authors.forename: Mitsuharu
authors.initials: M
authors.lastname: Yagi
authors.affiliation: Department of Biology, Complesso Universitario di Monte Sant'Angelo, University of Naples Federico II, Edificio 7, Via Cinthia, 80126, Naples, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Agnisola
authors.affiliation: Genome Evolution and Organization - Department BEOM, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Naples, Italy. giuseppe.donofrio@szn.it.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: D'Onofrio
mesh_terms: D025041:Animal Migration; D000818:Animals; D001482:Base Composition; D004734:Energy Metabolism; D005399:Fishes / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D005618:Fresh Water; D016678:Genome; D005880:Gills / Q000502:physiology; D010802:Phylogeny; D054712:Salinity; D012623:Seawater