Diverse strategies for ion regulation in fish collected from the ion-poor, acidic Rio Negro
We measured unidirectional ion fluxes of fish collected directly from the Rio Negro, an extremely dilute, acidic blackwater tributary of the Amazon. Kinetic analysis of Na+ uptake revealed that most species had fairly similar Jmax values, ranging from 1,150 to 1,750 nmol g-1 h-1, while Km values var...
| Autor principal: | Gonzalez, Richard J. |
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| Outros Autores: | Wilson, Rod W., Wood, Chris M., Patrick, Marjorie L., Val, Adalberto Luis |
| Grau: | Artigo |
| Idioma: | English |
| Publicado em: |
Physiological and Biochemical Zoology
2020
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| Acesso em linha: |
https://repositorio.inpa.gov.br/handle/1/19075 |
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oai:repositorio:1-19075 |
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oai:repositorio:1-19075 Diverse strategies for ion regulation in fish collected from the ion-poor, acidic Rio Negro Gonzalez, Richard J. Wilson, Rod W. Wood, Chris M. Patrick, Marjorie L. Val, Adalberto Luis Physiology Corydoras Julii Diagnostic Agent Fresh Water Sodium Water Adaptation Animals Brasil Catfish Chemistry Cichlid Comparative Study Environment Fish Ion Transport Metabolism Ph Physiology Adaptation, Physiological Animal Brasil Catfishes Cichlids Environment Fishes Fresh Water Hydrogen-ion Concentration Ion Transport Sodium Sodium Isotopes Water We measured unidirectional ion fluxes of fish collected directly from the Rio Negro, an extremely dilute, acidic blackwater tributary of the Amazon. Kinetic analysis of Na+ uptake revealed that most species had fairly similar Jmax values, ranging from 1,150 to 1,750 nmol g-1 h-1, while Km values varied to a greater extent. Three species had Km values <33 μmol L-1, while the rest had Km values ≥ 110 μmol L-1. Because of the extremely low Na+ concentration of Rio Negro water, the differences in Km values yield very different rates of Na+ uptake. However, regardless of the rate of Na+ uptake, measurements of Na+ efflux show that Na+ balance was maintained at very low Na+ levels (<50 μmol L-1) by most species. Unlike other species with high Km values, the catfish Corydoras julii maintained high rates of Na+ uptake in dilute waters by having a Jmax value at least 100% higher than the other species. Corydoras julii also demonstrated the ability to modulate kinetic parameters in response to changes in water chemistry. After 2 wk in 2 mmol L-1 NaCl, Jmax fell >50%, and Km dropped about 70%. The unusual acclimatory drop in Km may represent a mechanism to ensure high rates of Na+ uptake on return to dilute water. As well as being tolerant of extremely dilute waters, Rio Negro fish generally were fairly tolerant of low pH. Still, there were significant differences in sensitivity to pH among the species on the basis of degree of stimulation of Na+ efflux at low pH. There were also differences in sensitivity to low pH of Na+ uptake, and two species maintained significant rates of uptake even at pH 3.5. When fish were exposed to low pH in Rio Negro water instead of deionized water (with the same concentrations of major ions), the effects of low pH were reduced. This suggests that high concentrations of dissolved organic molecules in the water, which give it its dark tea color, may interact with the branchial epithelium in some protective manner. 2020-06-15T22:05:10Z 2020-06-15T22:05:10Z 2002 Artigo https://repositorio.inpa.gov.br/handle/1/19075 10.1086/339216 en Volume 75, Número 1, Pags. 37-47 Restrito Physiological and Biochemical Zoology |
| institution |
Instituto Nacional de Pesquisas da Amazônia - Repositório Institucional |
| collection |
INPA-RI |
| language |
English |
| topic |
Physiology Corydoras Julii Diagnostic Agent Fresh Water Sodium Water Adaptation Animals Brasil Catfish Chemistry Cichlid Comparative Study Environment Fish Ion Transport Metabolism Ph Physiology Adaptation, Physiological Animal Brasil Catfishes Cichlids Environment Fishes Fresh Water Hydrogen-ion Concentration Ion Transport Sodium Sodium Isotopes Water |
| spellingShingle |
Physiology Corydoras Julii Diagnostic Agent Fresh Water Sodium Water Adaptation Animals Brasil Catfish Chemistry Cichlid Comparative Study Environment Fish Ion Transport Metabolism Ph Physiology Adaptation, Physiological Animal Brasil Catfishes Cichlids Environment Fishes Fresh Water Hydrogen-ion Concentration Ion Transport Sodium Sodium Isotopes Water Gonzalez, Richard J. Diverse strategies for ion regulation in fish collected from the ion-poor, acidic Rio Negro |
| topic_facet |
Physiology Corydoras Julii Diagnostic Agent Fresh Water Sodium Water Adaptation Animals Brasil Catfish Chemistry Cichlid Comparative Study Environment Fish Ion Transport Metabolism Ph Physiology Adaptation, Physiological Animal Brasil Catfishes Cichlids Environment Fishes Fresh Water Hydrogen-ion Concentration Ion Transport Sodium Sodium Isotopes Water |
| description |
We measured unidirectional ion fluxes of fish collected directly from the Rio Negro, an extremely dilute, acidic blackwater tributary of the Amazon. Kinetic analysis of Na+ uptake revealed that most species had fairly similar Jmax values, ranging from 1,150 to 1,750 nmol g-1 h-1, while Km values varied to a greater extent. Three species had Km values <33 μmol L-1, while the rest had Km values ≥ 110 μmol L-1. Because of the extremely low Na+ concentration of Rio Negro water, the differences in Km values yield very different rates of Na+ uptake. However, regardless of the rate of Na+ uptake, measurements of Na+ efflux show that Na+ balance was maintained at very low Na+ levels (<50 μmol L-1) by most species. Unlike other species with high Km values, the catfish Corydoras julii maintained high rates of Na+ uptake in dilute waters by having a Jmax value at least 100% higher than the other species. Corydoras julii also demonstrated the ability to modulate kinetic parameters in response to changes in water chemistry. After 2 wk in 2 mmol L-1 NaCl, Jmax fell >50%, and Km dropped about 70%. The unusual acclimatory drop in Km may represent a mechanism to ensure high rates of Na+ uptake on return to dilute water. As well as being tolerant of extremely dilute waters, Rio Negro fish generally were fairly tolerant of low pH. Still, there were significant differences in sensitivity to pH among the species on the basis of degree of stimulation of Na+ efflux at low pH. There were also differences in sensitivity to low pH of Na+ uptake, and two species maintained significant rates of uptake even at pH 3.5. When fish were exposed to low pH in Rio Negro water instead of deionized water (with the same concentrations of major ions), the effects of low pH were reduced. This suggests that high concentrations of dissolved organic molecules in the water, which give it its dark tea color, may interact with the branchial epithelium in some protective manner. |
| format |
Artigo |
| author |
Gonzalez, Richard J. |
| author2 |
Wilson, Rod W. Wood, Chris M. Patrick, Marjorie L. Val, Adalberto Luis |
| author2Str |
Wilson, Rod W. Wood, Chris M. Patrick, Marjorie L. Val, Adalberto Luis |
| title |
Diverse strategies for ion regulation in fish collected from the ion-poor, acidic Rio Negro |
| title_short |
Diverse strategies for ion regulation in fish collected from the ion-poor, acidic Rio Negro |
| title_full |
Diverse strategies for ion regulation in fish collected from the ion-poor, acidic Rio Negro |
| title_fullStr |
Diverse strategies for ion regulation in fish collected from the ion-poor, acidic Rio Negro |
| title_full_unstemmed |
Diverse strategies for ion regulation in fish collected from the ion-poor, acidic Rio Negro |
| title_sort |
diverse strategies for ion regulation in fish collected from the ion-poor, acidic rio negro |
| publisher |
Physiological and Biochemical Zoology |
| publishDate |
2020 |
| url |
https://repositorio.inpa.gov.br/handle/1/19075 |
| _version_ |
1787142774461562880 |
| score |
11.755432 |