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Freshwater to seawater acclimation of juvenile bull sharks (Carcharhinus leucas): plasma osmolytes and Na+/K+-ATPase activity in gill, rectal gland, kidney and intestine.
J Comp Physiol B. 2005 Jan; 175(1):37-44.JC

Abstract

This study examined the osmoregulatory status of the euryhaline elasmobranch Carcharhinus leucas acclimated to freshwater (FW) and seawater (SW). Juvenile C. leucas captured in FW (3 mOsm l(-1) kg(-1)) were acclimated to SW (980-1,000 mOsm l(-1) kg(-1)) over 16 days. A FW group was maintained in captivity over a similar time period. In FW, bull sharks were hyper-osmotic regulators, having a plasma osmolarity of 595 mOsm l(-1) kg(-1). In SW, bull sharks had significantly higher plasma osmolarities (940 mOsm l(-1) kg(-1)) than FW-acclimated animals and were slightly hypo-osmotic to the environment. Plasma Na(+), Cl(-), K(+), Mg(2+), Ca(2+), urea and trimethylamine oxide (TMAO) concentrations were all significantly higher in bull sharks acclimated to SW, with urea and TMAO showing the greatest increase. Gill, rectal gland, kidney and intestinal tissue were taken from animals acclimated to FW and SW and analysed for maximal Na(+)/K(+)-ATPase activity. Na(+)/K(+)-ATPase activity in the gills and intestine was less than 1 mmol Pi mg(-1) protein h(-1) and there was no difference in activity between FW- and SW-acclimated animals. In contrast Na(+)/K(+)-ATPase activity in the rectal gland and kidney were significantly higher than gill and intestine and showed significant differences between the FW- and SW-acclimated groups. In FW and SW, rectal gland Na(+)/K(+)-ATPase activity was 5.6+/-0.8 and 9.2+/-0.6 mmol Pi mg(-1) protein h(-1), respectively. Na(+)/K(+)-ATPase activity in the kidney of FW and SW acclimated animals was 8.4+/-1.1 and 3.3+/-1.1 Pi mg(-1) protein h(-1), respectively. Thus juvenile bull sharks have the osmoregulatory plasticity to acclimate to SW; their preference for the upper reaches of rivers where salinity is low is therefore likely to be for predator avoidance and/or increased food abundance rather than because of a physiological constraint.

Authors+Show Affiliations

School of Life Sciences, The University of Queensland, Brisbane, QLD, 4072, Australia. richard.pillans@csiro.auNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

15565307

Citation

Pillans, Richard D., et al. "Freshwater to Seawater Acclimation of Juvenile Bull Sharks (Carcharhinus Leucas): Plasma Osmolytes and Na+/K+-ATPase Activity in Gill, Rectal Gland, Kidney and Intestine." Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology, vol. 175, no. 1, 2005, pp. 37-44.
Pillans RD, Good JP, Anderson WG, et al. Freshwater to seawater acclimation of juvenile bull sharks (Carcharhinus leucas): plasma osmolytes and Na+/K+-ATPase activity in gill, rectal gland, kidney and intestine. J Comp Physiol B. 2005;175(1):37-44.
Pillans, R. D., Good, J. P., Anderson, W. G., Hazon, N., & Franklin, C. E. (2005). Freshwater to seawater acclimation of juvenile bull sharks (Carcharhinus leucas): plasma osmolytes and Na+/K+-ATPase activity in gill, rectal gland, kidney and intestine. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology, 175(1), 37-44.
Pillans RD, et al. Freshwater to Seawater Acclimation of Juvenile Bull Sharks (Carcharhinus Leucas): Plasma Osmolytes and Na+/K+-ATPase Activity in Gill, Rectal Gland, Kidney and Intestine. J Comp Physiol B. 2005;175(1):37-44. PubMed PMID: 15565307.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Freshwater to seawater acclimation of juvenile bull sharks (Carcharhinus leucas): plasma osmolytes and Na+/K+-ATPase activity in gill, rectal gland, kidney and intestine. AU - Pillans,Richard D, AU - Good,Jonathan P, AU - Anderson,W Gary, AU - Hazon,Neil, AU - Franklin,Craig E, Y1 - 2004/11/24/ PY - 2004/09/21/accepted PY - 2004/11/27/pubmed PY - 2005/7/12/medline PY - 2004/11/27/entrez SP - 37 EP - 44 JF - Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology JO - J Comp Physiol B VL - 175 IS - 1 N2 - This study examined the osmoregulatory status of the euryhaline elasmobranch Carcharhinus leucas acclimated to freshwater (FW) and seawater (SW). Juvenile C. leucas captured in FW (3 mOsm l(-1) kg(-1)) were acclimated to SW (980-1,000 mOsm l(-1) kg(-1)) over 16 days. A FW group was maintained in captivity over a similar time period. In FW, bull sharks were hyper-osmotic regulators, having a plasma osmolarity of 595 mOsm l(-1) kg(-1). In SW, bull sharks had significantly higher plasma osmolarities (940 mOsm l(-1) kg(-1)) than FW-acclimated animals and were slightly hypo-osmotic to the environment. Plasma Na(+), Cl(-), K(+), Mg(2+), Ca(2+), urea and trimethylamine oxide (TMAO) concentrations were all significantly higher in bull sharks acclimated to SW, with urea and TMAO showing the greatest increase. Gill, rectal gland, kidney and intestinal tissue were taken from animals acclimated to FW and SW and analysed for maximal Na(+)/K(+)-ATPase activity. Na(+)/K(+)-ATPase activity in the gills and intestine was less than 1 mmol Pi mg(-1) protein h(-1) and there was no difference in activity between FW- and SW-acclimated animals. In contrast Na(+)/K(+)-ATPase activity in the rectal gland and kidney were significantly higher than gill and intestine and showed significant differences between the FW- and SW-acclimated groups. In FW and SW, rectal gland Na(+)/K(+)-ATPase activity was 5.6+/-0.8 and 9.2+/-0.6 mmol Pi mg(-1) protein h(-1), respectively. Na(+)/K(+)-ATPase activity in the kidney of FW and SW acclimated animals was 8.4+/-1.1 and 3.3+/-1.1 Pi mg(-1) protein h(-1), respectively. Thus juvenile bull sharks have the osmoregulatory plasticity to acclimate to SW; their preference for the upper reaches of rivers where salinity is low is therefore likely to be for predator avoidance and/or increased food abundance rather than because of a physiological constraint. SN - 0174-1578 UR - https://www.unboundmedicine.com/medline/citation/15565307/Freshwater_to_seawater_acclimation_of_juvenile_bull_sharks__Carcharhinus_leucas_:_plasma_osmolytes_and_Na+/K+_ATPase_activity_in_gill_rectal_gland_kidney_and_intestine_ L2 - http://dx.doi.org/10.1007/s00360-004-0460-2 DB - PRIME DP - Unbound Medicine ER -