TY - JOUR
T1 - Interactions of waterborne and dietary cadmium on the expression of calcium transporters in the gills of rainbow trout
T2 - Influence of dietary calcium supplementation
AU - Galvez, Fernando
AU - Franklin, Natasha M.
AU - Tuttle, Ryan B.
AU - Wood, Chris M.
N1 - Funding Information:
This work was supported by the grants to CMW from the Natural Sciences and Engineering Research Council Strategic Grants Program and CRD Program, the International Lead Zinc Research Organization, the International Zinc Association, the Nickel Producers Environmental Research Association, the International Copper Association, the Copper Development Association, Teck Cominco, Noranda-Falconbridge, CVRD Inco, Inc. and by grants to FG from the Louisiana State University Faculty Research Grant Program and the Ralph E. Powe Junior Faculty Enhancement Award from Oak Ridge Associated Universities. We thank Dr. Peter Chapman for helpful comments on the MS, and Drs. Mark Batzer and Andrew Whitehead for their generous use of equipment. CMW is supported by the Canada Research Chair Program.
PY - 2007/8/30
Y1 - 2007/8/30
N2 - Recent studies have shown that dietary Ca2+ supplementation strongly inhibits uptake of Ca2+ and Cd at the fish gill. To better understand the influence of dietary Ca2+ on branchial Ca2+ transport, we examined the expression of two trout gill calcium transporters during waterborne and dietary Cd exposure, at two different levels of dietary Ca2+. Quantitative polymerase chain reaction (PCR) was used to monitor epithelial calcium channel (ECaC) and sodium-calcium exchange (NCX) mRNA levels following 7-28 days of exposure to these treatments. In brief, juvenile rainbow trout (Oncorhynchus mykiss) were exposed to control, 3 μg/L waterborne Cd, 500 mg/kg dietary Cd, or a combined 3 μg/L waterborne plus 500 mg/kg dietary Cd exposure, supplemented with either 20 mg/g or 60 mg/g dietary calcium (Ca2+). Two-way analysis of variance was used to discern the main effects of Cd exposure and dietary Ca2+ supplementation on ECaC and NCX mRNA levels. We found that dietary Ca2+ supplementation decreased significantly ECaC mRNA expression on days 14 and 21. In comparison, NCX mRNA levels were not influenced by dietary Ca2+ supplementation, but rather were significantly inhibited in the combined waterborne and dietary Cd exposure on day 7 alone. Statistical analysis found no interactive effects between Cd exposure and dietary Ca2+ exposure at any time point, except for day 28.This study provides evidence of the importance of nutritional status on the transcriptional regulation of ion transport at the fish gill. We discuss the importance of diet and nutritional status to the development of new regulatory approaches, such as the biotic ligand model, which currently do not account for the significance of diet on metal bioavailability in aquatic organisms.
AB - Recent studies have shown that dietary Ca2+ supplementation strongly inhibits uptake of Ca2+ and Cd at the fish gill. To better understand the influence of dietary Ca2+ on branchial Ca2+ transport, we examined the expression of two trout gill calcium transporters during waterborne and dietary Cd exposure, at two different levels of dietary Ca2+. Quantitative polymerase chain reaction (PCR) was used to monitor epithelial calcium channel (ECaC) and sodium-calcium exchange (NCX) mRNA levels following 7-28 days of exposure to these treatments. In brief, juvenile rainbow trout (Oncorhynchus mykiss) were exposed to control, 3 μg/L waterborne Cd, 500 mg/kg dietary Cd, or a combined 3 μg/L waterborne plus 500 mg/kg dietary Cd exposure, supplemented with either 20 mg/g or 60 mg/g dietary calcium (Ca2+). Two-way analysis of variance was used to discern the main effects of Cd exposure and dietary Ca2+ supplementation on ECaC and NCX mRNA levels. We found that dietary Ca2+ supplementation decreased significantly ECaC mRNA expression on days 14 and 21. In comparison, NCX mRNA levels were not influenced by dietary Ca2+ supplementation, but rather were significantly inhibited in the combined waterborne and dietary Cd exposure on day 7 alone. Statistical analysis found no interactive effects between Cd exposure and dietary Ca2+ exposure at any time point, except for day 28.This study provides evidence of the importance of nutritional status on the transcriptional regulation of ion transport at the fish gill. We discuss the importance of diet and nutritional status to the development of new regulatory approaches, such as the biotic ligand model, which currently do not account for the significance of diet on metal bioavailability in aquatic organisms.
KW - Biotic ligand model
KW - Epithelial calcium channel (ECaC)
KW - mRNA levels
KW - Sodium calcium exchanger (NCX)
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U2 - 10.1016/j.aquatox.2007.04.013
DO - 10.1016/j.aquatox.2007.04.013
M3 - Article
C2 - 17645964
AN - SCOPUS:34547788832
VL - 84
SP - 208
EP - 214
JO - Aquatic Toxicology
JF - Aquatic Toxicology
SN - 0166-445X
IS - 2 SPEC. ISS.
ER -