TY - JOUR
T1 - Proteomic and physiological responses of leopard sharks (Triakis semifasciata) to salinity change
AU - Dowd, W. W.
AU - Harris, B. N.
AU - Cech, J. J.
AU - Kültz, D.
PY - 2010/1/15
Y1 - 2010/1/15
N2 - Partially euryhaline elasmobranchs may tolerate physiologically challenging, variable salinity conditions in estuaries as a tradeoff to reduce predation risk or to gain access to abundant food resources. To further understand these trade-offs and to evaluate the underlying mechanisms, we examined the responses of juvenile leopard sharks to salinity changes using a suite of measurements at multiple organizational levels: gill and rectal gland proteomes (using 2-D gel electrophoresis and tandem mass spectrometry), tissue biochemistry (Na +/K +-ATPase, caspase 3/7 and chymotrypsin-like proteasome activities), organismal physiology (hematology, plasma composition, muscle moisture) and individual behavior. Our proteomics results reveal coordinated molecular responses to low salinity - several of which are common to both rectal gland and gill - including changes in amino acid and inositol (i.e. osmolyte) metabolism, energy metabolism and proteins related to transcription, translation and protein degradation. Overall, leopard sharks employ a strategy of maintaining plasma urea, ion concentrations and Na +/K +-ATPase activities in the short-term, possibly because they rarely spend extended periods in low salinity conditions in the wild, but the sharks osmoconform to the surrounding conditions by 3 weeks. We found no evidence of apoptosis at the time points tested, while both tissues exhibited proteomic changes related to the cytoskeleton, suggesting that leopard sharks remodel existing osmoregulatory epithelial cells and activate physiological acclimatory responses to solve the problems posed by low salinity exposure. The behavioral measurements reveal increased activity in the lowest salinity in the short-term, while activity decreased in the lowest salinity in the long-term. Our data suggest that physiological/behavioral trade-offs are involved in using estuarine habitats, and pathway modeling implicates tumor necrosis factor α (TNFα) as a key node of the elasmobranch hyposmotic response network.
AB - Partially euryhaline elasmobranchs may tolerate physiologically challenging, variable salinity conditions in estuaries as a tradeoff to reduce predation risk or to gain access to abundant food resources. To further understand these trade-offs and to evaluate the underlying mechanisms, we examined the responses of juvenile leopard sharks to salinity changes using a suite of measurements at multiple organizational levels: gill and rectal gland proteomes (using 2-D gel electrophoresis and tandem mass spectrometry), tissue biochemistry (Na +/K +-ATPase, caspase 3/7 and chymotrypsin-like proteasome activities), organismal physiology (hematology, plasma composition, muscle moisture) and individual behavior. Our proteomics results reveal coordinated molecular responses to low salinity - several of which are common to both rectal gland and gill - including changes in amino acid and inositol (i.e. osmolyte) metabolism, energy metabolism and proteins related to transcription, translation and protein degradation. Overall, leopard sharks employ a strategy of maintaining plasma urea, ion concentrations and Na +/K +-ATPase activities in the short-term, possibly because they rarely spend extended periods in low salinity conditions in the wild, but the sharks osmoconform to the surrounding conditions by 3 weeks. We found no evidence of apoptosis at the time points tested, while both tissues exhibited proteomic changes related to the cytoskeleton, suggesting that leopard sharks remodel existing osmoregulatory epithelial cells and activate physiological acclimatory responses to solve the problems posed by low salinity exposure. The behavioral measurements reveal increased activity in the lowest salinity in the short-term, while activity decreased in the lowest salinity in the long-term. Our data suggest that physiological/behavioral trade-offs are involved in using estuarine habitats, and pathway modeling implicates tumor necrosis factor α (TNFα) as a key node of the elasmobranch hyposmotic response network.
KW - Elasmobranch
KW - Focal animal sampling
KW - Maldi-tof-tof mass spectrometry
KW - Na /k -atpase
KW - Osmoregulation
KW - Pathway analysis
KW - Proteomics
KW - Tumor necrosis factor
KW - Urea
UR - http://www.scopus.com/inward/record.url?scp=75249083774&partnerID=8YFLogxK
U2 - 10.1242/jeb.031781
DO - 10.1242/jeb.031781
M3 - Article
C2 - 20038654
AN - SCOPUS:75249083774
SN - 0022-0949
VL - 213
SP - 210
EP - 224
JO - Journal of Experimental Biology
JF - Journal of Experimental Biology
IS - 2
ER -