Functional and morphological plasticity of crocodile (Crocodylus porosus) salt glands

Cramp, Rebecca L., Meyer, Edward A., Sparks, Nicole and Franklin, Craig E. (2008) Functional and morphological plasticity of crocodile (Crocodylus porosus) salt glands. The Journal of Experimental Biology, 211 9: 1482-1489. doi:10.1242/jeb.015636

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Author Cramp, Rebecca L.
Meyer, Edward A.
Sparks, Nicole
Franklin, Craig E.
Title Functional and morphological plasticity of crocodile (Crocodylus porosus) salt glands
Formatted title
Functional and morphological plasticity of crocodile (Crocodylus porosus) salt glands
Journal name The Journal of Experimental Biology   Check publisher's open access policy
ISSN 0022-0949
1477-9145
Publication date 2008-05-01
Sub-type Article (original research)
DOI 10.1242/jeb.015636
Open Access Status File (Publisher version)
Volume 211
Issue 9
Start page 1482
End page 1489
Total pages 8
Place of publication Cambridge, England
Publisher The Company of Biologists Ltd.
Language eng
Subject C1
970106 Expanding Knowledge in the Biological Sciences
0608 Zoology
0606 Physiology
Abstract The estuarine crocodile, Crocodylus porosus, inhabits both freshwater and hypersaline waterways and maintains ionic homeostasis by excreting excess sodium and chloride ions via lingual salt glands. In the present study, we sought to investigate the phenotypic plasticity, both morphological and functional, in the lingual salt glands of the estuarine crocodile associated with chronic exposure to freshwater (FW) and saltwater (SW) environments. Examination of haematological parameters indicated that there were no long-term disruptions to ionic homeostasis with prolonged exposure to SW. Maximal secretory rates from the salt glands of SW-acclimated animals (100.8±14.7 µmol 100 g–0.7 body mass h–1) were almost three times greater than those of FW-acclimated animals (31.6±6.2 µmol 100 g–0.7 body mass h–1). There were no differences in the mass-specific metabolic rate of salt gland tissue slices from FW- and SW-acclimated animals (558.9±49.6 and 527.3±142.8 µl O2 g–1 h–1, respectively). Stimulation of the tissue slices from SW-acclimated animals by methacholine resulted in a 33% increase in oxygen consumption rate. There was no significant increase in the metabolic rate of tissues from FW-acclimated animals in response to methacholine. Morphologically, the secretory cells from the salt glands of SW-acclimated animals were larger than those of FW-acclimated animals. In addition, there were significantly more mitochondria per unit volume in secretory tissue from SW-acclimated animals. The results from this study demonstrate that the salt glands of C. porosus are phenotypically plastic, both morphologically and functionally and acclimate to changes in environmental salinity.
Formatted abstract
The estuarine crocodile, Crocodylus porosus, inhabits both freshwater and hypersaline waterways and maintains ionic homeostasis by excreting excess sodium and chloride ions via lingual salt glands. In the present study, we sought to investigate the phenotypic plasticity, both morphological and functional, in the lingual salt glands of the estuarine crocodile associated with chronic exposure to freshwater (FW) and saltwater (SW) environments. Examination of haematological parameters indicated that there were no long-term disruptions to ionic homeostasis with prolonged exposure to SW. Maximal secretory rates from the salt glands of SW-acclimated animals (100.8±14.7 µmol 100 g0.7 body mass h–1) were almost three times greater than those of FW-acclimated animals (31.6±6.2 µmol 100 g–0.7 body mass h–1). There were no differences in the mass-specific metabolic rate of salt gland tissue slices from FW- and SW-acclimated animals (558.9±49.6 and 527.3±142.8 µl O2 g–1 h–1, respectively). Stimulation of the tissue slices from SW-acclimated animals by methacholine resulted in a 33% increase in oxygen consumption rate. There was no significant increase in the metabolic rate of tissues from FW-acclimated animals in response to methacholine. Morphologically, the secretory cells from the salt glands of SW-acclimated animals were larger than those of FW-acclimated animals. In addition, there were significantly more mitochondria per unit volume in secretory tissue from SW-acclimated animals. The results from this study demonstrate that the salt glands of C. porosus are phenotypically plastic, both morphologically and functionally and acclimate to changes in environmental salinity.
Keyword osmoregulation
reptile
tissue respirometry
stereology
transmission electron microscopy
Q-Index Code C1
Q-Index Status Confirmed Code
Additional Notes First published online April 18, 2008

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2009 Higher Education Research Data Collection
School of Biological Sciences Publications
Ecology Centre Publications
 
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Citation counts: TR Web of Science Citation Count  Cited 12 times in Thomson Reuters Web of Science Article | Citations
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Created: Thu, 05 Feb 2009, 02:10:55 EST by Gail Walter on behalf of School of Biological Sciences