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 (<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.

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.

MEASUREMENT OF PLASMA CORTISOL LEVELS IN THE EEL ANGUILLA ANGUILLA IN RELATION TO OSMOTIC ADJUSTMENTS

1971 ◽  
Vol 50 (1) ◽  
pp. 75-96 ◽  
Author(s):  
J. N. BALL ◽  
I. CHESTER JONES ◽  
M. E. FORSTER ◽  
G. HARGREAVES ◽  
E. F. HAWKINS ◽  
...  
Keyword(s):  
Plasma Cortisol ◽  
Sea Water ◽  
Anguilla Anguilla ◽  
Plasma Cortisol Level ◽  
Hormonal Control ◽  
Total Cortisol ◽  
Competitive Protein Binding ◽  
Low Levels ◽  
Cortisol Levels

SUMMARY The competitive protein-binding radioassay (CPB method) of Murphy (1967) has been adapted to determine total cortisol levels in the plasma of the eel, Anguilla anguilla L. Validation of the method for this species depended in part on the development of a chromatographic—fluorimetric technique for eel cortisol, following classical procedures and using radioactive tracers; by this means, the specificity of the CPB method for cortisol in eel plasma was established. Accuracy, precision and sensitivity of the CPB method were also investigated and were shown to be satisfactory. Plasma total cortisol levels were determined in eels during osmotic adjustments after transfers from fresh water (FW) to sea-water (SW) and vice versa, and from FW to distilled water. Plasma osmotic pressure and/or sodium levels were monitored simultaneously, to follow the progress of osmotic regulation. In only one of the transfer situations did the plasma cortisol level change significantly, showing a marked transitory increase during the first few days after transfer from FW to SW, corresponding to the development and correction of an 'osmotic crisis'. Plasma cortisol levels were the same in eels adapted for long periods to FW and to SW. Plasma cortisol fell to extremely low levels after hypophysectomy. These results are discussed in the light of the literature on hormonal control of osmoregulatory mechanisms in the eel, with particular emphasis on the role of adrenocorticosteroids in ionic regulation of animals in SW.

Neural modulation of salt secretion in teleostopercular epithelium by 2-adrenergic receptors and inositol 1,4,5-trisphosphate

1998 ◽  
Vol 201 (12) ◽  
pp. 1959-1965 ◽  
Author(s):  
WS Marshall ◽  
RM Duquesnay ◽  
JM Gillis ◽  
SE Bryson ◽  
CM Liedtke
Keyword(s):  
Fresh Water ◽  
Adrenergic Receptors ◽  
Sea Water ◽  
Significant Rise ◽  
Secretion Rate ◽  
Estuarine Fish ◽  
Dependent Manner ◽  
Cl Secretion ◽  
Inositol 1,4,5 Trisphosphate ◽  
Salt Secretion

Opercular epithelia from seawater-adapted killifish (Fundulus heteroclitus) were dissected with the nerve intact, mounted in Ussing-style membrane chambers and bathed in symmetrical saline solutions. Nerve stimulation rapidly inhibited transepithelial current (a measure of Cl- secretion rate) by 27.3+/-3.3 % (N=22), and the effect could be sustained for more than 10 min using intermittent pulse trains at 10 Hz. The effect was blocked in a dose-dependent manner by yohimbine, but not by propranolol, atropine or tubocurarine, indicating mediation by &lt;IMG src="/images/symbols/&agr ;.gif" WIDTH= "9" HEIGHT="12" ALIGN="BOTTOM" NATURALSIZEFLAG="3"&gt;2-adrenergic receptors. The effect was also present, but significantly diminished, in opercular membranes from animals that had been transferred to sea water for 48 h (18+/-8.6 % inhibition, N=14). The resting current and the effect were absent in membranes from freshwater-adapted animals. The addition of clonidine (1.0 micromol l-1 serosal side) started to inhibit Cl- current after 40-60 s; immediately before this, at 30 s, there was a significant rise (P&lt;0.05, N=14) in tissue inositol 1,4,5, -trisphosphate (InsP3) level, but no change at later times, compared with LiCl-treated control membranes and measured by radiolabeled receptor assay. The results indicate that seawater-adapted killifish can decrease their Cl- secretion rate through the action of the sympathetic nervous system, a response appropriate for the entry of estuarine fish to fresh water, and that the effect is mediated by &lt;IMG src="/images/symbols/&agr ;.gif" WIDTH="9" HEIGHT="12" ALIGN="BOTTOM" NATURALSIZEFLAG="3"&gt;2-adrenoceptors via InsP3. The results imply that euryhaline fish entering fresh water can undergo an autonomic reflex reduction in salt secretion that does not require a stress response.

Adaptive hyperplasia of epidermal chloride-secreting cells in fry of mummichog, Fundulus heteroclitus L., incubated and reared in supranormal salinity

1979 ◽  
Vol 57 (9) ◽  
pp. 1803-1807 ◽  
Author(s):  
K.-L. Tay ◽  
E. T. Garside
Keyword(s):  
Fresh Water ◽  
Fundulus Heteroclitus ◽  
Sea Water

Cells, structurally identical with branchial chloride-secreting cells, were observed to be broadly distributed in buccal and pharyngeal epithelia and various regions of the trunk epidermis, in early fry of the mummichog, Fundulus heteroclitus L., that had been incubated in embryonal and alevin stages in sea water concentrated by additional salts to 60‰ salinity, at 20 °C. Although there was some proliferation of these cells in the buccal and pharyngeal epithelia, such apparently adaptive hyperplasia and hypertrophy of these cells did not occur in early fry that had previous incubation and rearing in seawater concentrations of 30, 20, and 10‰ salinity (S), and in fresh water (< 0.5‰ S)

IMITATION OF THE ADRENO-CORTICAL RESPONSE TO SURGERY BY INTRAVENOUS INFUSION OF SYNTHETIC HUMAN ACTH

1973 ◽  
Vol 72 (1) ◽  
pp. 75-80
Author(s):  
Henrik Kehlet ◽  
Christian Binder ◽  
Christen Engbæk
Keyword(s):  
Intravenous Infusion ◽  
Time Course ◽  
Cortical Response ◽  
Secretion Rate ◽  
Major Surgery ◽  
Acth Secretion ◽  
Dose Rates

ABSTRACT The concentration of plasma corticosteroids was followed during major surgery and during the infusion of synthetic human ACTH at dose rates varying from 2400 ng to 15 000 ng per hour. The results showed that the time course of plasma corticosteroids during major surgery was intermediate between that obtained during the infusion of 7500 and 15 000 ng synthetic human ACTH per hour. This gives an estimated ACTH secretion rate during major surgery of between 7500 ng and 15 000 ng per hour.

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