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Chris M Wood - One of the best experts on this subject based on the ideXlab platform.
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Acute temperature effects on metabolic rate, ventilation, diffusive water exchange, osmoregulation, and acid–base status in the Pacific hagfish (Eptatretus stoutii)
Journal of Comparative Physiology B, 2019Co-Authors: Marina Giacomin, Patricia M Schulte, Chris M WoodAbstract:The Pacific hagfish ( Eptatretus stoutii ) is a representative of the most basal extant craniates, and is a marine Osmoconformer with an extremely low metabolic rate (MO_2 = 475 µmol O_2/kg/h at 12 °C). We investigated potential physiological trade-offs associated with compensatory changes in gill ventilation and perfusion when 12 °C-acclimated hagfish were acutely exposed to 7 °C or 17 °C, as reflected in diffusive unidirectional water flux ( $${J_{{{\text{H}}_2}{\text{O}}}}$$ J H 2 O , measured with tritiated water: ^3H_2O), net ammonia flux ( J _amm), and plasma ion and acid–base status. $${J_{{{\text{H}}_2}{\text{O}}}}$$ J H 2 O was high (~ 1.4 L/kg/h at 12 °C) in comparison to marine teleosts and elasmobranchs. MO_2 increased linearly with temperature ( R ^2 = 0.991), and was more sensitive ( Q _10 = 3.22) in the 12–7 °C range than either J _amm (1.86) or $${J_{{{\text{H}}_2}{\text{O}}}}$$ J H 2 O (1.35), but the pattern reversed from 12 to 17 °C ( Q _10s: MO_2 = 2.77, J _amm = 2.88, $${J_{{{\text{H}}_2}{\text{O}}}}$$ J H 2 O = 4.01). Heart rate, ventilatory index (a proxy for total ventilation), and coughing frequency also increased but with different patterns. At 17 °C, plasma [Ca^2+] and [Mg^2+] decreased, although osmolality increased, associated with elevations in plasma [Na^+] and [Cl^−]. Blood pH and PCO_2 were unaffected by acute temperature changes while [HCO_3^−] increased. Hyperoxia (PO_2 > 300 Torr) attenuated the increase in $${J_{{{\text{H}}_2}{\text{O}}}}$$ J H 2 O at 17 °C, did not affect J _amm, and had diverse effects on plasma ion and acid–base status. Our results suggest a clear osmorespiratory compromise occurring for the diffusive water fluxes as a result of acute temperature changes in this Osmoconformer.
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acute temperature effects on metabolic rate ventilation diffusive water exchange osmoregulation and acid base status in the pacific hagfish eptatretus stoutii
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 2019Co-Authors: Marina Giacomin, Patricia M Schulte, Chris M WoodAbstract:The Pacific hagfish (Eptatretus stoutii) is a representative of the most basal extant craniates, and is a marine Osmoconformer with an extremely low metabolic rate (MO2 = 475 µmol O2/kg/h at 12 °C). We investigated potential physiological trade-offs associated with compensatory changes in gill ventilation and perfusion when 12 °C-acclimated hagfish were acutely exposed to 7 °C or 17 °C, as reflected in diffusive unidirectional water flux ( $${J_{{{\text{H}}_2}{\text{O}}}}$$ , measured with tritiated water: 3H2O), net ammonia flux (Jamm), and plasma ion and acid–base status. $${J_{{{\text{H}}_2}{\text{O}}}}$$ was high (~ 1.4 L/kg/h at 12 °C) in comparison to marine teleosts and elasmobranchs. MO2 increased linearly with temperature (R2 = 0.991), and was more sensitive (Q10 = 3.22) in the 12–7 °C range than either Jamm (1.86) or $${J_{{{\text{H}}_2}{\text{O}}}}$$ (1.35), but the pattern reversed from 12 to 17 °C (Q10s: MO2 = 2.77, Jamm = 2.88, $${J_{{{\text{H}}_2}{\text{O}}}}$$ = 4.01). Heart rate, ventilatory index (a proxy for total ventilation), and coughing frequency also increased but with different patterns. At 17 °C, plasma [Ca2+] and [Mg2+] decreased, although osmolality increased, associated with elevations in plasma [Na+] and [Cl−]. Blood pH and PCO2 were unaffected by acute temperature changes while [HCO3−] increased. Hyperoxia (PO2 > 300 Torr) attenuated the increase in $${J_{{{\text{H}}_2}{\text{O}}}}$$ at 17 °C, did not affect Jamm, and had diverse effects on plasma ion and acid–base status. Our results suggest a clear osmorespiratory compromise occurring for the diffusive water fluxes as a result of acute temperature changes in this Osmoconformer.
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Differential Effects of Temperature on Oxygen Consumption and Branchial Fluxes of Urea, Ammonia, and Water in the Dogfish Shark (Squalus acanthias suckleyi)
Physiological and Biochemical Zoology, 2017Co-Authors: Marina Giacomin, Patricia M Schulte, Chris M WoodAbstract:AbstractEnvironmental temperature can greatly influence the homeostasis of ectotherms through its effects on biochemical reactions and whole-animal physiology. Elasmobranchs tend to be N limited and are Osmoconformers, retaining ammonia and urea-N at the gills and using the latter as a key osmolyte to maintain high blood osmolality. However, the effects of temperature on these key processes remain largely unknown. We evaluated the effects of acute exposure to different temperatures (7°, 12°, 15°, 18°, 22°C) on oxygen consumption, ammonia, urea-N, and diffusive water fluxes at the gills of Squalus acanthias suckleyi. We hypothesized that as metabolic demand for oxygen increased with temperature, the fluxes of ammonia, urea-N, and 3H2O at the gills would increase in parallel with those of oxygen. Oxygen consumption (overall Q10=1.76 from 7.5° to 22°C) and water fluxes (overall Q10=1.96) responded to increases in temperature in a similar, almost linear, manner. Ammonia-N efflux rates varied the most, increas...
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Drinking and water permeability in the Pacific hagfish, Eptatretus stoutii
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 2017Co-Authors: Chris N. Glover, Chris M Wood, Greg G. GossAbstract:Hagfish are Osmoconformers, maintaining an internal osmolality that matches their seawater habitats. Hagfish would, therefore, appear to have no physiological need to drink, but previous studies are equivocal regarding whether drinking in hagfish occurs. The current study addressed this knowledge gap, by examining drinking and water permeability in the Pacific hagfish, Eptatretus stoutii. One-third of analysed hagfish were shown to accumulate radiolabelled drinking rate markers (tritiated inulin and polyethylene glycol-4000) in their gut tissues; however, this was attributed to the presence of markers in the blood perfusing the digestive tract, following absorption through paracellular pathways at the gill. No accumulation of marker was observed in hagfish subjected to more dilute (75% seawater) or more concentrated (125% seawater) media. Diffusive water efflux, measured by tritiated water washout, was shown to be very high, with 50% of body water exchanged within 14 to 16 min, depending on exposure salinity. In full-strength seawater, the total exchangeable pool of water was 78% of hagfish mass. We conclude that hagfish do not drink, and their high water permeability is likely to result in rapid osmotic equilibration under circumstances where perturbations may occur.
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Effect of environmental salinity manipulation on uptake rates and distribution patterns of waterborne amino acids in the Pacific hagfish
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2016Co-Authors: Chris N. Glover, Tamzin A. Blewett, Chris M WoodAbstract:Abstract Among vertebrates, hagfish are the only known iono- and Osmoconformers, and the only species thus far documented to absorb amino acids directly across the skin. In the current study, short-term (6 h) manipulations of exposure salinities (75–125% seawater) were conducted to determine whether changes in osmotic demands influenced the uptake and tissue distribution of waterborne amino acids (alanine, glycine and phenylalanine), in the Pacific hagfish, Eptatretus stoutii . No changes in erythrocyte or muscle amino acid accumulation rates were noted, but the patterns of plasma amino acid accumulation were suggestive of regulation. Contrary to expectations, glycine transport across the skin in vitro was enhanced in the lowest exposure salinity, but no other salinity-dependent changes were demonstrated. Overall, this study indicates that uptake and distribution of amino acids varies with salinity, but not in a manner that is consistent with a role for the studied amino acids in maintaining osmotic balance in hagfish.
Marina Giacomin - One of the best experts on this subject based on the ideXlab platform.
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Acute temperature effects on metabolic rate, ventilation, diffusive water exchange, osmoregulation, and acid–base status in the Pacific hagfish (Eptatretus stoutii)
Journal of Comparative Physiology B, 2019Co-Authors: Marina Giacomin, Patricia M Schulte, Chris M WoodAbstract:The Pacific hagfish ( Eptatretus stoutii ) is a representative of the most basal extant craniates, and is a marine Osmoconformer with an extremely low metabolic rate (MO_2 = 475 µmol O_2/kg/h at 12 °C). We investigated potential physiological trade-offs associated with compensatory changes in gill ventilation and perfusion when 12 °C-acclimated hagfish were acutely exposed to 7 °C or 17 °C, as reflected in diffusive unidirectional water flux ( $${J_{{{\text{H}}_2}{\text{O}}}}$$ J H 2 O , measured with tritiated water: ^3H_2O), net ammonia flux ( J _amm), and plasma ion and acid–base status. $${J_{{{\text{H}}_2}{\text{O}}}}$$ J H 2 O was high (~ 1.4 L/kg/h at 12 °C) in comparison to marine teleosts and elasmobranchs. MO_2 increased linearly with temperature ( R ^2 = 0.991), and was more sensitive ( Q _10 = 3.22) in the 12–7 °C range than either J _amm (1.86) or $${J_{{{\text{H}}_2}{\text{O}}}}$$ J H 2 O (1.35), but the pattern reversed from 12 to 17 °C ( Q _10s: MO_2 = 2.77, J _amm = 2.88, $${J_{{{\text{H}}_2}{\text{O}}}}$$ J H 2 O = 4.01). Heart rate, ventilatory index (a proxy for total ventilation), and coughing frequency also increased but with different patterns. At 17 °C, plasma [Ca^2+] and [Mg^2+] decreased, although osmolality increased, associated with elevations in plasma [Na^+] and [Cl^−]. Blood pH and PCO_2 were unaffected by acute temperature changes while [HCO_3^−] increased. Hyperoxia (PO_2 > 300 Torr) attenuated the increase in $${J_{{{\text{H}}_2}{\text{O}}}}$$ J H 2 O at 17 °C, did not affect J _amm, and had diverse effects on plasma ion and acid–base status. Our results suggest a clear osmorespiratory compromise occurring for the diffusive water fluxes as a result of acute temperature changes in this Osmoconformer.
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acute temperature effects on metabolic rate ventilation diffusive water exchange osmoregulation and acid base status in the pacific hagfish eptatretus stoutii
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 2019Co-Authors: Marina Giacomin, Patricia M Schulte, Chris M WoodAbstract:The Pacific hagfish (Eptatretus stoutii) is a representative of the most basal extant craniates, and is a marine Osmoconformer with an extremely low metabolic rate (MO2 = 475 µmol O2/kg/h at 12 °C). We investigated potential physiological trade-offs associated with compensatory changes in gill ventilation and perfusion when 12 °C-acclimated hagfish were acutely exposed to 7 °C or 17 °C, as reflected in diffusive unidirectional water flux ( $${J_{{{\text{H}}_2}{\text{O}}}}$$ , measured with tritiated water: 3H2O), net ammonia flux (Jamm), and plasma ion and acid–base status. $${J_{{{\text{H}}_2}{\text{O}}}}$$ was high (~ 1.4 L/kg/h at 12 °C) in comparison to marine teleosts and elasmobranchs. MO2 increased linearly with temperature (R2 = 0.991), and was more sensitive (Q10 = 3.22) in the 12–7 °C range than either Jamm (1.86) or $${J_{{{\text{H}}_2}{\text{O}}}}$$ (1.35), but the pattern reversed from 12 to 17 °C (Q10s: MO2 = 2.77, Jamm = 2.88, $${J_{{{\text{H}}_2}{\text{O}}}}$$ = 4.01). Heart rate, ventilatory index (a proxy for total ventilation), and coughing frequency also increased but with different patterns. At 17 °C, plasma [Ca2+] and [Mg2+] decreased, although osmolality increased, associated with elevations in plasma [Na+] and [Cl−]. Blood pH and PCO2 were unaffected by acute temperature changes while [HCO3−] increased. Hyperoxia (PO2 > 300 Torr) attenuated the increase in $${J_{{{\text{H}}_2}{\text{O}}}}$$ at 17 °C, did not affect Jamm, and had diverse effects on plasma ion and acid–base status. Our results suggest a clear osmorespiratory compromise occurring for the diffusive water fluxes as a result of acute temperature changes in this Osmoconformer.
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Differential Effects of Temperature on Oxygen Consumption and Branchial Fluxes of Urea, Ammonia, and Water in the Dogfish Shark (Squalus acanthias suckleyi)
Physiological and Biochemical Zoology, 2017Co-Authors: Marina Giacomin, Patricia M Schulte, Chris M WoodAbstract:AbstractEnvironmental temperature can greatly influence the homeostasis of ectotherms through its effects on biochemical reactions and whole-animal physiology. Elasmobranchs tend to be N limited and are Osmoconformers, retaining ammonia and urea-N at the gills and using the latter as a key osmolyte to maintain high blood osmolality. However, the effects of temperature on these key processes remain largely unknown. We evaluated the effects of acute exposure to different temperatures (7°, 12°, 15°, 18°, 22°C) on oxygen consumption, ammonia, urea-N, and diffusive water fluxes at the gills of Squalus acanthias suckleyi. We hypothesized that as metabolic demand for oxygen increased with temperature, the fluxes of ammonia, urea-N, and 3H2O at the gills would increase in parallel with those of oxygen. Oxygen consumption (overall Q10=1.76 from 7.5° to 22°C) and water fluxes (overall Q10=1.96) responded to increases in temperature in a similar, almost linear, manner. Ammonia-N efflux rates varied the most, increas...
D. J. S. Montagnes - One of the best experts on this subject based on the ideXlab platform.
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Evidence that the rotifer Brachionus plicatilis is not an Osmoconformer
Marine Biology, 2005Co-Authors: C. D. Lowe, S. J. Kemp, A. D. Bates, D. J. S. MontagnesAbstract:The rotifer Brachionus plicatilis is euryhaline (growing between 2 and 97 ppt) and has previously been considered an Osmoconformer. We suggest that B. plicatilis is an osmoregulator, exhibiting a pattern of Na^+/K^+ ATPase activity in response to salinity consistent with that of other osmoregulating euryhaline invertebrates. To examine salinity tolerance, growth rates between 5 and 60 ppt were determined. The activity of Na^+/K^+ ATPase was examined, over the same range of salinities, by measuring ATPase activity in rotifer homogenates in the presence and absence of a Na^+/K^+ ATPase inhibitor. Maximum specific growth rate (0.95 day^−1) occurred at 16 ppt, highest mean amictic eggs per female (1.41) occurred at 20 ppt, and both parameters decreased rapidly as salinity increased. Egg development time was constant with salinity at 0.92 days. The activity of Na^+/K^+ ATPase per milligram protein increased from 3.9 µmol h^−1 at 5 ppt to 6.8 µmol h^−1 at 50 ppt and accounted for 15 and 30% of total ATPase activity, respectively. We suggest that these observations are consistent with increasing stress at high salinities and the occurrence of a hypo-osmoregulatory response. Given the high ATP consumption of Na^+/K^+ ATPase at high salinities, it is possible that a proportion of the corresponding decreases in growth rate and egg production are a direct cost of regulation.
Patricia M Schulte - One of the best experts on this subject based on the ideXlab platform.
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Acute temperature effects on metabolic rate, ventilation, diffusive water exchange, osmoregulation, and acid–base status in the Pacific hagfish (Eptatretus stoutii)
Journal of Comparative Physiology B, 2019Co-Authors: Marina Giacomin, Patricia M Schulte, Chris M WoodAbstract:The Pacific hagfish ( Eptatretus stoutii ) is a representative of the most basal extant craniates, and is a marine Osmoconformer with an extremely low metabolic rate (MO_2 = 475 µmol O_2/kg/h at 12 °C). We investigated potential physiological trade-offs associated with compensatory changes in gill ventilation and perfusion when 12 °C-acclimated hagfish were acutely exposed to 7 °C or 17 °C, as reflected in diffusive unidirectional water flux ( $${J_{{{\text{H}}_2}{\text{O}}}}$$ J H 2 O , measured with tritiated water: ^3H_2O), net ammonia flux ( J _amm), and plasma ion and acid–base status. $${J_{{{\text{H}}_2}{\text{O}}}}$$ J H 2 O was high (~ 1.4 L/kg/h at 12 °C) in comparison to marine teleosts and elasmobranchs. MO_2 increased linearly with temperature ( R ^2 = 0.991), and was more sensitive ( Q _10 = 3.22) in the 12–7 °C range than either J _amm (1.86) or $${J_{{{\text{H}}_2}{\text{O}}}}$$ J H 2 O (1.35), but the pattern reversed from 12 to 17 °C ( Q _10s: MO_2 = 2.77, J _amm = 2.88, $${J_{{{\text{H}}_2}{\text{O}}}}$$ J H 2 O = 4.01). Heart rate, ventilatory index (a proxy for total ventilation), and coughing frequency also increased but with different patterns. At 17 °C, plasma [Ca^2+] and [Mg^2+] decreased, although osmolality increased, associated with elevations in plasma [Na^+] and [Cl^−]. Blood pH and PCO_2 were unaffected by acute temperature changes while [HCO_3^−] increased. Hyperoxia (PO_2 > 300 Torr) attenuated the increase in $${J_{{{\text{H}}_2}{\text{O}}}}$$ J H 2 O at 17 °C, did not affect J _amm, and had diverse effects on plasma ion and acid–base status. Our results suggest a clear osmorespiratory compromise occurring for the diffusive water fluxes as a result of acute temperature changes in this Osmoconformer.
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acute temperature effects on metabolic rate ventilation diffusive water exchange osmoregulation and acid base status in the pacific hagfish eptatretus stoutii
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 2019Co-Authors: Marina Giacomin, Patricia M Schulte, Chris M WoodAbstract:The Pacific hagfish (Eptatretus stoutii) is a representative of the most basal extant craniates, and is a marine Osmoconformer with an extremely low metabolic rate (MO2 = 475 µmol O2/kg/h at 12 °C). We investigated potential physiological trade-offs associated with compensatory changes in gill ventilation and perfusion when 12 °C-acclimated hagfish were acutely exposed to 7 °C or 17 °C, as reflected in diffusive unidirectional water flux ( $${J_{{{\text{H}}_2}{\text{O}}}}$$ , measured with tritiated water: 3H2O), net ammonia flux (Jamm), and plasma ion and acid–base status. $${J_{{{\text{H}}_2}{\text{O}}}}$$ was high (~ 1.4 L/kg/h at 12 °C) in comparison to marine teleosts and elasmobranchs. MO2 increased linearly with temperature (R2 = 0.991), and was more sensitive (Q10 = 3.22) in the 12–7 °C range than either Jamm (1.86) or $${J_{{{\text{H}}_2}{\text{O}}}}$$ (1.35), but the pattern reversed from 12 to 17 °C (Q10s: MO2 = 2.77, Jamm = 2.88, $${J_{{{\text{H}}_2}{\text{O}}}}$$ = 4.01). Heart rate, ventilatory index (a proxy for total ventilation), and coughing frequency also increased but with different patterns. At 17 °C, plasma [Ca2+] and [Mg2+] decreased, although osmolality increased, associated with elevations in plasma [Na+] and [Cl−]. Blood pH and PCO2 were unaffected by acute temperature changes while [HCO3−] increased. Hyperoxia (PO2 > 300 Torr) attenuated the increase in $${J_{{{\text{H}}_2}{\text{O}}}}$$ at 17 °C, did not affect Jamm, and had diverse effects on plasma ion and acid–base status. Our results suggest a clear osmorespiratory compromise occurring for the diffusive water fluxes as a result of acute temperature changes in this Osmoconformer.
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Differential Effects of Temperature on Oxygen Consumption and Branchial Fluxes of Urea, Ammonia, and Water in the Dogfish Shark (Squalus acanthias suckleyi)
Physiological and Biochemical Zoology, 2017Co-Authors: Marina Giacomin, Patricia M Schulte, Chris M WoodAbstract:AbstractEnvironmental temperature can greatly influence the homeostasis of ectotherms through its effects on biochemical reactions and whole-animal physiology. Elasmobranchs tend to be N limited and are Osmoconformers, retaining ammonia and urea-N at the gills and using the latter as a key osmolyte to maintain high blood osmolality. However, the effects of temperature on these key processes remain largely unknown. We evaluated the effects of acute exposure to different temperatures (7°, 12°, 15°, 18°, 22°C) on oxygen consumption, ammonia, urea-N, and diffusive water fluxes at the gills of Squalus acanthias suckleyi. We hypothesized that as metabolic demand for oxygen increased with temperature, the fluxes of ammonia, urea-N, and 3H2O at the gills would increase in parallel with those of oxygen. Oxygen consumption (overall Q10=1.76 from 7.5° to 22°C) and water fluxes (overall Q10=1.96) responded to increases in temperature in a similar, almost linear, manner. Ammonia-N efflux rates varied the most, increas...
Marta Marques Souza - One of the best experts on this subject based on the ideXlab platform.
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lead hampers gill cell volume regulation in marine crabs stronger effect in a weak osmoregulator than in an Osmoconformer
Aquatic Toxicology, 2012Co-Authors: Enelise M. Amado, Carolina A. Freire, M Grassi, Marta Marques SouzaAbstract:Abstract Hepatus pudibundus is a strictly marine Osmoconformer crab, while Callinectes ornatus inhabits estuarine areas, behaving as a weak hyper-osmoregulator in diluted seawater. Osmoconformers are expected to have higher capacity for cell volume regulation, but gill cells of a regulator are expected to display ion transporters to a higher degree. The influence of lead nitrate (10 μM) on the ability of isolated gill cells from both species to volume regulate under isosmotic and hyposmotic conditions were here evaluated. Without lead, under a 25% hyposmotic shock, the gill cells of both species were quite capable of cell volume maintenance. Cells of C. ornatus, however, had a little swelling (5%) during the hyposmotic shock of greater intensity (50%), while cells of H. pudibundus were still capable of volume regulation. In the presence of lead, even under isosmoticity, the gill cells of both species showed about 10% volume reduction, indicating that lead promotes the loss of water by the cells. When lead was associated with 25% and 50% hyposmotic shock, C. ornatus cells lost more volume (15%), when compared to isosmotic conditions, while H. pudibundus cells showed volume regulation. We then analyzed the possible ways of action of lead on the mechanisms of cell volume regulation in the two species. Verapamil (100 μM) was used to inhibit Ca2+ channels, ouabain (100 μM) to inhibit Na+/K+-ATPase, and HgCl2 (100 μM) to inhibit aquaporins. Our results suggest that: (1) Ca2+ channels are candidates for lead entry into gill cells of H. pudibundus and C. ornatus, being the target of lead action in these cells; (2) aquaporins are much more relevant for water flux in H. pudibundus; and (3) the Na+/K+-ATPase is much more relevant for volume regulation in C. ornatus. Osmoregulators may be more susceptible to metal contamination than Osmoconformers, especially in situations of reduced salinity, for two basic reasons: (1) lower capacity of volume regulation and (2) putative higher uptake of Pb2+ through ionic pathways that operate in salt absorption, such as, for example, the Na+/K+-ATPase.
