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S. D. McCormick

Publications and source records attributed to S. D. McCormick.

At least 55 records · Page 3Linked to original sources
USGS1999

Time course of salinity adaptation a strongly euryhaline estuarine teleost, Fundulus Heteroclitus: A multivariable approach

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 ( I sc ; 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.

Journal of Experimental Biology↗
USGS1999

Metabolic rates in an anadromous clupeid, the American shad ( Alosa sapidissima )

To assess the energetics of migration in an anadromous fish, adult American shad ( Alosa sapidissima ) were swum in a large respirometer at a range of speeds (1.0–2.3 body lengths (BL) s −1 , 13–24 °C). Metabolic rate (M O2 ) was logarithmically related to swimming speed (Bl s −1 ; r 2 = 0.41, slope = 0.23 ± 0.037) and tailbeat frequency (beats × min −1 ; r 2 = 0.52, slope = 0.003 ± 0.0003). Temperature had a significant effect on metabolic rate ( r 2 = 0.41) with a Q 10 of 2.2. Standard metabolic rate (SMR), determined directly after immobilization with the neuroblocker gallamine triethiodide, ranged from 2.2–6.2 mmolO 2 kg −1 h −1 and scaled with mass (W) such that SMR = 4.0 (±0.03)W 0.695(±0.15) . Comparison of directly determined and extrapolated SMR suggests that swimming respirometry provides a good estimate of SMR in this species, given the differences in basal activity monitored by the two methods. Overall, American shad metabolic rates (M O2 and SMR) were intermediate between salmonids and fast-swimming perciforms, including tunas, and may be a result of evolutionary adaptation to their active pelagic, schooling life history. This study demonstrates variability in metabolic strategy among anadromous fishes that may be important to understanding the relative success of different migratory species under varying environmental conditions.

Journal of Comparative Physiology B: Biochemical, ↗
USGS1999

Influence of cortisol, growth hormone, insulin-like growth factor I and 3,3′,5-triiodo-l-thyronine on hypoosmoregulatory ability in the euryhaline teleost Fundulus heteroclitus

The capacity of cortisol, ovine growth hormone (oGH), recombinant bovine insulin-like growth factor I (rbIGF-I) and 3,3′,5-triiodo-l-thyronine (T 3 ) to increase hypoosmoregulatory capacity in the euryhaline teleost Fundulus heteroclitus was examined. Fish acclimated to brackish water (BW, 10 ppt salinity) were injected with a single dose of hormone suspended in oil and transferred to seawater (SW, 35 ppt salinity) 10 days post-injection. Fish were sampled 24 h after transfer and plasma osmolality and gill Na + , K + -ATPase activity were examined. Transfer from BW to SW induced significantly increased plasma osmolality but not gill Na + , K + -ATPase activity. Cortisol (50 μg g −1 body weight) improved the ability to maintain plasma osmolality and to increase gill Na + , K + -ATPase activity. oGH (5 μg g −1 body weight) also increased hypoosmoregulatory ability and gill Na + , K + -ATPase activity. A cooperation between oGH and cortisol was observed in increasing hypoosmoregulatory ability but not in increasing gill Na + , K + -ATPase activity. rbIGF-I (0.5 μg g −1 body weight) alone was without effect in increasing salinity tolerance or gill Na + , K + -ATPase activity. rbIGF-I and oGH showed a positive interaction in increasing salinity tolerance, but not gill Na + , K + -ATPase activity. Treatment with T 3 (5 μg g −1 body weight) alone did not increase salinity tolerance or gill Na + , K + -ATPase activity, and there was no consistent significant interaction between cortisol and T 3 or between GH and T 3 . The results confirm the classical role of cortisol as a seawater-adapting hormone and indicate an interaction between cortisol and the GH/IGF-I axis during seawater acclimation of Fundulus heteroclitus.

Fish Physiology and Biochemistry↗
USGS1999

Migration timing of Atlantic salmon smolts relative to environmental and physiological factors

We determined the migration timing of fry‐stocked smolts of Atlantic salmon Salmo salar relative to environmental and physiological factors, by using net weirs and counting fences in three tributaries of the West River, Vermont. Smolt migration began in late April and early May when water temperature was 5°C, peak movements occurred in early and mid‐May at temperatures exceeding 8°C, and migration was complete by early June. Within this seasonal window, significant differences in migration timing and gill Na + ,K + ‐ATPase activity occurred among tributaries. In both years of the study, smolts tended to migrate earlier and exhibit greater gill Na + ,K + ‐ATPase activity in the warmest tributary than in the coolest tributary. Smolt migration timing differed most among tributaries in mid‐May when (1) water temperatures were more than 8°C, (2) smolts peaked in gill Na + ,K + ‐ATPase activity, and (3) discharge peaked, stimulating smolt migration. Smolts captured after the migratory period had lower gill Na + ,K + ‐ATPase activity than migrating smolts. Relating smolt physiology to migration was crucial for explaining complex interactions among water temperature, discharge, and smolt behavior during both the onset and cessation of migratory activity. Because the period between onset of migration and loss of smolt physiological characteristics may be brief, delays in downstream passage that may occur at dams must be minimized to maximize the successful recruitment of smolts to the marine environment.

Transactions of the American Fisheries Society↗
USGS1998

Evidence for growth hormone/insulin-like growth factor I axis regulation of seawater acclimation in the euryhaline teleost Fundulus heteroclitus

The ability of ovine growth hormone (oGH), recombinant bovine insulin-like growth factor I (rbIGF-I), recombinant human insulin-like growth factor II (rhIGF-II), and bovine insulin to increase hypoosmoregulatory capacity in the euryhaline teleost Fundulus heteroclitus was examined. Fish acclimated to brackish water (BW, 10 ppt salinity, 320 mOsm/kg H 2 O) were injected with a single dose of hormone and transferred to seawater (SW, 35 ppt salinity, 1120 mOsm/kg H 2 O) 2 days later. Fish were sampled 24 h after transfer and plasma osmolality, plasma glucose, and gill Na + ,K + -ATPase activity were examined. Transfer from BW to SW increased plasma osmolality and gill Na + ,K + -ATPase activity. Transfer from BW to BW had no effect on these parameters. rbIGF-I (0.05, 0.1, and 0.2 μg/g) improved the ability to maintain plasma osmolality and to increase gill Na + , K + -ATPase activity in a dose-dependent manner. oGH (0.5, 1, and 2 μg/g) also increased hypoosmoregulatory ability but only the higher doses (2 μg/g) significantly increased gill Na + ,K + -ATPase activity. oGH (1 μg/g) and rbIGF-I (0.1 μg/g) had a significantly greater effect on plasma osmolality and gill Na + ,K + -ATPase activity than either hormone alone. rhIGF-II (0.05, 0.1, and 0.2 μg/g) and bovine insulin (0.01 and 0.05 μg/g) were without effect. The results suggest a role of GH and insulin-like growth factor I (IGF-I) in seawater acclimation of F. heteroclitus. Based on these findings and previous studies, it is concluded that the capacity of the GH/IGF-I axis to increase hypoosmoregulatory ability may be a common feature of euryhalinity in teleosts.

Connecticut↗
USGS1998

Regulation of gill cytosolic corticosteroid receptors in juvenile Atlantic salmon: Interaction effects of growth hormone with prolactand triiodothyronine

The potential effects of growth hormone (GH), prolactin (Prl), and triiodothyronine (T 3 ) on gill Na + ,K + -ATPase activity and corticosteroid receptor (CR) concentration ( B max ) and dissociation constant ( K d ) were examined in juvenile Atlantic salmon ( Salmo salar ). Compared to controls, fish injected with GH (ovine, 5.0 μg g −1 ) had significantly greater gill Na + ,K + -ATPase activity after 7 and 14 days. Gill CR B max and K d were significantly elevated on day 7, but not day 14. T 3 also significantly increased CR B max . The effect of GH on CR B max was also additive with T 3 (5.0 μg g −1 ) treatment. There was a synergistic effect on CR B max when purified coho salmon GH (csGH, 0.1 μg g −1 ) was injected in combination with T 3 (1.6 μg g −1 ). Prl (ovine, 5.0 μg g −1 ; purified coho salmon, 0.1 μg g −1 ) did not significantly alter gill CR B max . Although Prl limited the increase in CR B max by GH, the effect was not signicant. T 3 and Prl did not have an effect on K d . GH significantly increased gill Na + ,K + -ATPase activity, T 3 administration did not have a significant effect, and Prl-treated fish had significantly lower gill Na + ,K + -ATPase activity. The results indicate that T 3 acts additively with GH, while Prl has no effect in regulating CR B max . An increase in cytosolic CR by GH and T 3 , but not Prl, may regulate gill responsiveness to cortisol and be an important mechanism in the endocrine control of physiological changes during the parr–smolt transformation.

General and Comparative Endocrinology↗
USGS1998

Repeated acute stress reduces growth rate of Atlantic salmon parr and alters plasma levels of growth hormone, insulin-like growth factor I and cortisol

Atlantic salmon ( Salmo salar ) parr were subjected to acute handling stresses and growth-monitored for at least 30 days. In fish stressed twice daily, growth rate in weight was 61% lower than controls after 11 days (1.00 vs. 2.57% day −1 ) and over a 30 day period it was 50% lower than controls (1.53 vs. 3.07% day −1 ). In fish stressed once daily, growth rate was 18% lower than controls after 10 days (2.17 vs. 2.63% day −1 ) and over a 30-day period it was 34% lower than controls (1.71 vs. 2.59% day −1 ). In fish stressed once daily, food consumption was reduced by 62% and 37% after 17 and 37 days, respectively. At the end of 40 days of acute stress once daily, control and stressed fish were sampled 1 h prior to, 3 and 7 h after a stress event. Plasma growth hormone levels were significantly higher in the stressed group than in the controls prior to and 7 h after stress. Plasma insulin-like growth factor I (IGF-I) levels were higher in the stressed group only 3 and 7 h after stress. Plasma cortisol levels were lower in the stressed group prior to and 3 h after stress. The results indicate that acute stressors decrease growth of Atlantic salmon parr, with increasing frequency of stress having a more rapid and greater effect.

Aquaculture↗
USGS1998

Osmoregulatory actions of the GH/IGF axis in non-salmonid teleosts

Salmonid fishes provided the first findings on the influence of the growth hormone (GH)/insulin-like growth factor I (IGF-I) axis on osmoregulation in teleost fishes. Recent studies on non-salmonid species, however, indicate that this physiological action of the GH/IGF-I axis is not restricted to salmonids or anadromous fishes. GH-producing cells in the pituitary of fish acclimated to different salinities show different degrees of activation depending on the species studied. Plasma GH levels either increase or do not change after transfer of fish from freshwater to seawater. Treatment with GH or IGF-I increases salinity tolerance and/or increases gill Na + ,K + -ATPase activity of killifish ( Fundulus heteroclitus ), tilapia ( Oreochromis mossambicus and Oreochromis niloticus ) and striped bass ( Morone saxatilis ). As in salmonids, a positive interaction between GH and cortisol for improving hypoosmoregulatory capacity has been described in tilapia ( O . mossambicus ). Research on the osmoregulatory role of the GH/IGF-I axis is derived from a small number of teleost species. The study of more species with different osmoregulary patterns will be necessary to fully clarify the osmoregulatory role of GH/IGF-I axis in fish. The available data does suggest, however, that the influence of the GH/IGF-I axis on osmoregulation may be a common feature of euryhalinity in teleosts.

Comparative Biochemistry and Physiology, Part B: B↗
USGS1997

The loss of hyperosmoregulatory ability in migrating juvenile American shad, Alosa sapidissima

Investigations on juvenile American shad ( Alosa sapidissima ) revealed several physiological changes associated with downstream migration. Plasma chloride decreased 20% in wild juvenile shad during the autumn migration. Migrants had lower condition factor and hematocrit than non-migrant shad captured by beach seining. Gill Na + ,K + -ATPase activity of migrant shad was higher than non-migrant; a 2.5-fold increase was observed in 1993, while a 57% increase was observed in 1994. Similar changes were observed in laboratory studies of shad maintained in fresh water under simulated natural temperature and photoperiod. Plasma chloride dropped 68% and gill Na + ,K + -ATPase activity increased 3-fold over a 3-month period. Decreased plasma chloride was associated with increased mortality. Increases in gill Na + ,K + -ATPase activity decreases in plasma chloride and osmolality, and incidence of mortality were delayed and moderated, but not eliminated, in shad maintained at constant temperature (24°C). Shad did not survive in fresh water past December regardless of temperature regime. In seawater, all shad survived and showed no perturbation of plasma chloride at 24°C or simulated natural temperature (above 4°C). The decline in hyperosmoregulatory ability, as influenced by declining temperatures, may serve as a proximate cue for autumnal migration.

Canadian Journal of Fisheries and Aquatic Sciences↗