title: Evolution of oxygen secretion in fishes and the emergence of a complex physiological system.
abstract: We have reconstructed the events that led to the evolution of a key physiological innovation underpinning the large adaptive radiation of fishes, namely their unique ability to secrete molecular oxygen (O2). We show that O2 secretion into the swimbladder evolved some 100 million years after another O2-secreting system in the eye. We unravel the likely sequence in which the functional components of both systems evolved. These components include ocular and swimbladder countercurrent exchangers, the Bohr and Root effects, the buffering power and surface histidine content of hemoglobins, and red blood cell Na+/H+ exchange activity. Our synthesis reveals the dynamics of gains and losses of these multiple traits over time, accounting for part of the huge diversity of form and function in living fishes.
authors.affiliation: School of Biological Sciences, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK. michaelb@liv.ac.uk
authors.forename: Michael
authors.initials: M
authors.lastname: Berenbrink
authors.forename: Pia
authors.initials: P
authors.lastname: Koldkjaer
authors.forename: Oliver
authors.initials: O
authors.lastname: Kepp
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Cossins
mesh_terms: D000222:Adaptation, Physiological; D000400:Air Sacs / Q000098:blood supply / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D005075:Biological Evolution; D002021:Buffers; D002196:Capillaries / Q000502:physiology; D002829:Choroid / Q000098:blood supply / Q000502:physiology; D004058:Diffusion; D004777:Environment; D004912:Erythrocytes / Q000502:physiology; D005399:Fishes / Q000033:anatomy & histology / Q000145:classification / Q000502:physiology*; D006454:Hemoglobins / Q000737:chemistry / Q000378:metabolism*; D006639:Histidine / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D010100:Oxygen / Q000378:metabolism*; D010108:Oxyhemoglobins / Q000378:metabolism; D010802:Phylogeny; D017923:Sodium-Hydrogen Exchangers / Q000097:blood / Q000378:metabolism; D013045:Species Specificity
chemical_list: D002021:Buffers; D006454:Hemoglobins; D010108:Oxyhemoglobins; D017923:Sodium-Hydrogen Exchangers; D006639:Histidine; D010100:Oxygen