Ca2+ transport by opercular epithelium of the fresh water adapted euryhaline teleost, Fundulus heteroclitus

1995 ◽  
Vol 165 (4) ◽  
pp. 268-277 ◽  
Author(s):  
W. S. Marshall ◽  
S. E. Bryson ◽  
J. S. Burghardt ◽  
P. M. Verbost
Keyword(s):  
Fresh Water ◽  
Fundulus Heteroclitus ◽  
Euryhaline Teleost

Control of epithelial Cl(−) secretion by basolateral osmolality in the euryhaline teleost Fundulus heteroclitus

2000 ◽  
Vol 203 (12) ◽  
pp. 1897-1905 ◽  
Author(s):  
W.S. Marshall ◽  
S.E. Bryson ◽  
T. Luby
Keyword(s):  
Cyclic Amp ◽  
Fresh Water ◽  
Fundulus Heteroclitus ◽  
Sea Water ◽  
Short Circuit ◽  
Cell Swelling ◽  
Hypotonic Shock ◽  
Cl Secretion ◽  
Basolateral Side ◽  
Euryhaline Teleost

Euryhaline teleost fish adapt rapidly to salinity change and reduce their rate of ion secretion on entry to fresh water. Killifish (Fundulus heteroclitus) transferred from full-strength sea water to fresh water showed large reductions in plasma [Na(+)] and osmolality at 6 h which were corrected by 24 h. To mimic this in vitro, a hypotonic shock of 20–70 mosmol kg(−)(1) was applied on the basolateral side of opercular epithelia. This hypotonic shock reversibly reduced the short-circuit current (I(sc), equivalent to the rate of secretion of Cl(−)) in a dose-dependent fashion, with a 40 mosmol kg(−)(1) hypotonic shock reducing I(sc) by 58+/−4.6 % in 40 min. Similar reductions in [NaCl], but with added mannitol to maintain osmolality, were without effect, indicating that the effect was purely osmotic. Hypotonic inhibition of I(sc) was accompanied by reductions in epithelial conductance (G(t)) but no significant change in transepithelial potential (V(t)). The hypotonic inhibition was apparently not Ca(2+)-mediated because Ca(2+)-depleted salines, thapsigargin and ionomycin all failed to block the reduction in I(sc) produced by hypotonic shock. The inhibition was not mediated via a reduction in intracellular cyclic AMP level because cyclic AMP levels, measured by radioimmunoassay, were unchanged by hypotonic shock and by 1.0 micromol l(−)(1) clonidine (which inhibits I(sc) by changing intracellular [Ca(2+)]) but were increased markedly by 1.0 micromol l(−)(1) isoproterenol, a positive control. The protein tyrosine kinase inhibitor genistein (100 micromol l(−)(1)), but not its inactive analogue daidzein, inhibited I(sc) in normal osmolality but produced a stimulation of I(sc) after hypotonic shock (and after clonidine treatment). The inhibitory effects of genistein and hypotonicity were not additive, suggesting that the same portion of the I(sc) was inhibited by both treatments. These data are consistent with a model for Cl(−) transport regulation involving tyrosine phosphorylation in cell-swelling-induced inhibition of Cl(−) secretion when euryhaline teleosts adapt to fresh water.

Thermal preferences of mummichog, Fundulus heteroclitus L., and banded killifish, F. diaphanus (LeSueur), (Cyprinodontidae) in relation to thermal acclimation and salinity

1977 ◽  
Vol 55 (7) ◽  
pp. 1190-1194 ◽  
Author(s):  
E. T. Garside ◽  
G. C. Morrison
Keyword(s):  
Fresh Water ◽  
Fundulus Heteroclitus ◽  
Sea Water ◽  
Thermal Acclimation ◽  
Thermal Gradients ◽  
Frequency Distributions ◽  
Preferred Temperatures ◽  
Typical Habitat ◽  
Thermal Preferences ◽  
Banded Killifish

Frequency distributions corresponding to various levels of thermal acclimation from 5 to 35 °C were recorded for samples of marine mummichog, Fundulus heteroclitus L., and samples of freshwater banded killifish, F. diaphanus (LeSueur), in thermal gradients formed in columns of fresh water (< 0.5‰ salinity) or sea water (32‰ salinity). Mean preferred temperatures comprised roughly parallel but irregularly inflected trends for the two series of tests, within each species. In mummichog, preferred temperatures for corresponding thermal acclimations ranged from 3 to 6 °C higher in tests conducted in sea water. In banded killifish, preferred temperatures for corresponding thermal acclimations ranged from 5 to 8 °C higher in fresh water. Thus, each species regularly preferred higher temperatures in salinity which approximated that of the typical habitat. The inference to be taken is that the unusual salinity for each species places an extraordinary osmoregulative load which influences the reactions of the fish to the series of thermal or other correlated stimuli in the gradient.

scholarly journals Time course of salinity adaptation in a strongly euryhaline estuarine teleost, fundulus heteroclitus: a multivariable approach

1999 ◽  
Vol 202 (11) ◽  
pp. 1535-1544 ◽  
Author(s):  
W.S. Marshall ◽  
T.R. Emberley ◽  
T.D. Singer ◽  
S.E. Bryson ◽  
S.D. Mccormick
Keyword(s):  
Fresh Water ◽  
Plasma Cortisol ◽  
Time Course ◽  
Fundulus Heteroclitus ◽  
Citrate Synthase ◽  
Sea Water ◽  
Short Circuit ◽  
Secretion Rate ◽  
Ion Secretion ◽  
Cortisol Levels

Freshwater-adapted killifish (Fundulus heteroclitus) were transferred directly from soft fresh water to full-strength sea water for periods of 1 h, 3 h, 8 h and 1, 2, 7, 14 and 30 days. Controls were transferred to fresh water for 24 h. Measured variables included: blood [Na+], osmolality, glucose and cortisol levels, basal and stimulated rates of ion transport and permeability of in vitro opercular epithelium, gill Na+/K+-ATPase and citrate synthase activity and chloride cell ultrastructure. These data were compared with previously published killifish cystic fibrosis transmembrane conductance regulator (kfCFTR) expression in the gills measured over a similar time course. Plasma cortisol levels peaked at 1 h, coincident with a rise in plasma [Na+]. At 8 h after transfer to sea water, a time at which previous work has shown kfCFTR expression to be elevated, blood osmolality and [Na+] were high, and cortisol levels and opercular membrane short-circuit current (Isc; a measure of Cl- secretion rate) were low. The 24 h group, which showed the highest level of kfCFTR expression, had the highest plasma [Na+] and osmolality, elevated plasma cortisol levels, significantly lower opercular membrane resistance, an increased opercular membrane ion secretion rate and collapsed tubule inclusions in mitochondria-rich cells, but no change in gill Na+/K+-ATPase and citrate synthase activity or plasma glucose levels. Apparently, killifish have a rapid (&lt;1 h) cortisol response to salinity coupled to subsequent (8–48 h) expression of kfCFTR anion channel proteins in existing mitochondria-rich cells that convert transport from ion uptake to ion secretion.

A novel 14-3-3 gene is osmoregulated in gill epithelium of the euryhaline teleost Fundulus heteroclitus

2001 ◽  
Vol 204 (17) ◽  
pp. 2975-2985 ◽  
Author(s):  
Dietmar Kültz ◽  
Devulapalli Chakravarty ◽  
Tadepalli Adilakshmi
Keyword(s):  
Signal Transduction ◽  
Amino Acid ◽  
Fundulus Heteroclitus ◽  
Sea Water ◽  
Amino Acid Residues ◽  
Gill Epithelium ◽  
Protein Levels ◽  
Euryhaline Teleost ◽  
Binding Groove ◽  
High Level

SUMMARY We have cloned and analyzed the full-length coding sequence and 3′ untranslated region (UTR) of a unique 14-3-3 gene of the euryhaline teleost Fundulus heteroclitus, which we named 14-3-3.a. Phylogenetic analysis of the deduced amino acid sequence revealed that the 14-3-3.a gene product is most similar to vertebrate 14-3-3ζ and β, yet it displays considerable divergence to known classes of vertebrate 14-3-3 isoforms. The N and C termini of 14-3-3.a are the most unique regions, whereas the amino acid residues forming the amphipathic ligand-binding groove are highly conserved. F. heteroclitus 14-3-3.a mRNA expression is high in gill epithelium, moderate in intestine and brain, and low in gonads, white muscle and heart. Because 14-3-3 proteins are important molecular scaffolds and cofactors for phosphoproteins and signaling complexes, the high level of 14-3-3.a expression in gill epithelium of the euryhaline teleost F. heteroclitus suggests that it is crucial for signal transduction in gill epithelial cells. We provide evidence that 14-3-3.a is involved in osmosensory signal transduction by showing that its mRNA and protein levels in gill epithelium, but not in any other tissue analyzed, increase two- to fourfold within 24h of salinity transfer of fish from sea water to fresh water. These data are clear evidence for an important role of 14-3-3.a in the remodeling of gill epithelium during transition of euryhaline fish between plasma-hyperosmotic and plasma-hyposmotic environments.

Atrial natriuretic factor and salt adaptation in the teleost fish Gila atraria

1988 ◽  
Vol 255 (6) ◽  
pp. F1281-F1286 ◽  
Author(s):  
C. Westenfelder ◽  
F. M. Birch ◽  
R. L. Baranowski ◽  
M. J. Rosenfeld ◽  
D. K. Shiozawa ◽  
...  
Keyword(s):  
Salt Tolerance ◽  
Fresh Water ◽  
Teleost Fish ◽  
Atrial Natriuretic Factor ◽  
Salt Adaptation ◽  
Fresh Water Fish ◽  
Fish Heart ◽  
Natriuretic Factor ◽  
Euryhaline Teleost ◽  
Atrial Natriuretic

It is unknown whether atrial natriuretic factor (ANF) is a mediator of environmental salt tolerance in euryhaline teleost fish. This was investigated in anesthetized Gila atraria, a euryhaline teleost native to springs of pleistocene Lake Bonneville. Plasma levels of immunoreactive (ir) ANF [using anti-human ANF-(99-126) antibodies] in fish obtained from a "fresh water" spring were significantly lower (146 +/- 27) than those in fish obtained from a "1% NaCl" spring (347 +/- 21 pg/ml, P less than 0.01). Electron micrographs of fish atrial and ventricular cardiocytes demonstrated many perinuclear granules, which closely resembled ANF-containing secretory granules seen in mammalian atriocytes. Fish heart extract contained ANF-like material of 3 kDa, which caused a marked diuresis and natriuresis in rats. In a second study, fish from a 1% NaCl spring were kept in tanks. One-third of the fish were maintained in 1% NaCl and one-third each were either adapted to fresh- or high-salt water. After 12 days, plasma irANF levels in 1% NaCl fish were 343 +/- 55, in fresh water fish 213 +/- 20 and in high-NaCl fish 691 +/- 79 pg/ml. These values differed significantly from each other (P less than 0.01). There was a close correlation between plasma irANF levels and both environmental and internal salt concentration. These data suggest that piscine ANF is an as yet unrecognized mediator of salt tolerance in this teleost and that ANF in these animals closely resembles mammalian ANF.

Influence of osmotic stress on upper lethal temperatures in the cyprinodontid fish Fundulus heteroclitus (L.)

1972 ◽  
Vol 50 (6) ◽  
pp. 787-791 ◽  
Author(s):  
E. T. Garside ◽  
Z. K. Chin-Yuen-Kee
Keyword(s):  
Thermal Stress ◽  
Osmotic Stress ◽  
Fresh Water ◽  
Thermal Tolerance ◽  
Fundulus Heteroclitus ◽  
Thermal Acclimation ◽  
Lethal Temperature ◽  
Lethal Temperatures

Upper lethal temperatures determined for the mummichog Fundulus heteroclitus (L.) for exposures of 10 000 min ranged from 18.58C to 36.31C. Osmotic acclimations were prepared at 0, 14, and 32‰ salinity (S), at thermal acclimations of 5 and 15C, and at 14 and 32‰ S at 25C. Mummichog could not survive in the acclimatory combination of 0‰ S at 25C. Subsamples from these acclimatory combinations were exposed to thermal stress at 0, 14, and 32‰ S. Highest upper lethal temperatures were observed in isosmotic test salinity (14‰). Intermediate lethal levels occurred in seawater (32‰ S) and the lowest lethal temperatures occurred in fresh water (0‰ S). Upper lethal temperature increased with increasing thermal acclimation but generally, prior osmotic experience did not modify thermal tolerance. There was no relation between order of death and size in 18 of the 24 test combinations. In the remaining six, the largest members died first in four and the smallest died first in two test combinations.

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