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dc.contributor.authorGonzalez, Richard J.-
dc.contributor.authorBrauner, Colin John-
dc.contributor.authorWang, Yuxiang-
dc.contributor.authorRichards, Jeffrey G.-
dc.contributor.authorPatrick, Marjorie L.-
dc.contributor.authorXi, W.-
dc.contributor.authorMatey, Victoria E.-
dc.contributor.authorVal, Adalberto Luis-
dc.date.accessioned2020-06-15T21:53:55Z-
dc.date.available2020-06-15T21:53:55Z-
dc.date.issued2010-
dc.identifier.urihttps://repositorio.inpa.gov.br/handle/1/18342-
dc.description.abstractSoon after hatching, the osteoglossid fish Arapaima gigas undergoes a rapid transition from a water breather to an obligate air breather. This is followed by a gradual disappearance of gill lamellae, which leaves smooth filaments with a reduced branchial diffusion capacity due to loss of surface area, and a fourfold increase in diffusion distance. This study evaluated the effects these changes have on gill function by examining two size classes of fish that differ in gill morphology. In comparison to smaller fish (∼67.5 g), which still have lamellae, larger fish (∼724.2 g) without lamellae took up a slightly greater percentage of O2 across the gills (30.1% vs. 23.9%), which indicates that the morphological changes do not place limitations on O 2 uptake in larger fish. Both size groups excreted similar percentages of CO2 across the gills (85%-90%). However, larger fish had higher blood Pco2 (26.5±1.9 vs. 16.5±1.5 mmHg) and HCO3-(40.2±2.9 vs. 33.6±4.5 mmol L -1) concentra- 3 tions and lower blood pH (7.58±0.01 vs. 7.70±0.04) than did smaller fish, despite having lower mass-specific metabolismssuggesting a possible diffusion limitation for CO2 excretion in larger fish. With regard to ion regulation, rates of diffusive Na+ loss were about 3.5 times higher in larger fish than they were in smaller fish, despite the lowered branchial diffusion capacity, and rates of Na+ uptake were higher by about the same amount despite 40% lower activity of branchial Na+/K+-ATPase. Kinetic analysis of Na+ uptake revealed an extremely low-affinity (K+587. 9±169.5 μmol L-1), low- m capacity (Jmax=265. 7±56.8 nmol g-1 h-1) transport system. Max These data may reflect a general reduction in the role of the gills in ion balance. Renal Na+/K-ATPase activity was 5-10 times higher than Na+/K+-ATPase activity in the gills, and urine : plasma ratios for Na+ and Cl- were very low (0.001- 0.005) relative to that of other fish, which suggested an increased role for dietary salt intake and renal salt retention and which was representative of a more "terrestrial" mode of ion regulation. Such de-emphasis of branchial ion regulation confers greatly reduced sensitivity of diffusive ion loss to low water pH. Ammonia excretion also appeared to be impacted by gill changes. Rates of ammonia excretion in larger fish were onethird less than that in smaller fish, despite larger fish having blood ammonia concentrations that were twice as high. © 2010 by The University of Chicago. All rights reserved.en
dc.language.isoenpt_BR
dc.relation.ispartofVolume 83, Número 2, Pags. 322-332pt_BR
dc.rightsRestrito*
dc.subjectAdenosine Triphosphatase (potassium Sodium)en
dc.subjectCarbon Dioxideen
dc.subjectSodiumen
dc.subjectAir-breathing Organismen
dc.subjectAmmoniaen
dc.subjectCarbon Dioxideen
dc.subjectConcentration (composition)en
dc.subjectData Acquisitionen
dc.subjectDieten
dc.subjectDiffusionen
dc.subjectExcretionen
dc.subjectFinfishen
dc.subjectFunctional Morphologyen
dc.subjectHatchingen
dc.subjectIon Exchangeen
dc.subjectMetabolismen
dc.subjectOntogenyen
dc.subjectOxygenen
dc.subjectPhen
dc.subjectSize Structureen
dc.subjectTransport Processen
dc.subjectAnimalsen
dc.subjectBreathingen
dc.subjectFishen
dc.subjectGillen
dc.subjectGrowth, Development And Agingen
dc.subjectHistologyen
dc.subjectLung Gas Exchangeen
dc.subjectMetabolismen
dc.subjectOxygen Consumptionen
dc.subjectPhysiologyen
dc.subjectTransport At The Cellular Levelen
dc.subjectAnimalen
dc.subjectBiological Transporten
dc.subjectCarbon Dioxideen
dc.subjectFishesen
dc.subjectGillsen
dc.subjectOxygen Consumptionen
dc.subjectRespirationen
dc.subjectRespiratory Transporten
dc.subjectSodiumen
dc.subjectSodium-potassium-exchanging Atpaseen
dc.subjectArapaima Gigasen
dc.subjectOsteoglossidaeen
dc.titleImpact of Ontogenetic Changes in Branchial Morphology on Gill Function in Arapaima gigasen
dc.typeArtigopt_BR
dc.identifier.doi10.1086/648568-
dc.publisher.journalPhysiological and Biochemical Zoologypt_BR
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