The effects of hypophysectomy on seasonal changes in plasma freezing-point depression, protein 'antifreeze,' and Na+ and Cl− concentrations of winter flounder (Pseudopleuronectes americanus)

1978 ◽  
Vol 56 (1) ◽  
pp. 109-113 ◽  
Author(s):  
G. L. Fletcher ◽  
C. M. Campbell ◽  
C. L. Hew
Keyword(s):  
Seasonal Changes ◽  
Freezing Point ◽  
Early Summer ◽  
Winter Flounder ◽  
Day Length ◽  
Freezing Point Depression ◽  
Pseudopleuronectes Americanus ◽  
Ambient Seawater ◽  
Annual Increase ◽  
Annual Changes

The annual changes in plasma Na+ and Cl− concentrations took place in the absence of the pituitary, although the magnitude of the change was significantly reduced. The annual increase in plasma freezing-point depression also occurred in the absence of the pituitary. However the decrease normally observed in the spring and early summer did not occur.Sham-operated winter flounder transferred from ambient seawater (−1 °C) and day length to warm water (6–12 °C) and 18-h day length showed a reduction in plasma Cl− concentration and freezing-point depression and a loss of the protein 'antifreeze.' Hypophysectomized flounder treated in the same way showed a reduction in plasma Cl−, but no decline in freezing-point depression and protein 'antifreeze.'These results suggest that an intact pituitary is necessary for the disappearance of the protein 'antifreeze' from the plasma of the winter flounder.

Circannual cycles of blood plasma freezing point and Na+ and Cl− concentrations in Newfoundland winter flounder (Pseudopleuronectes americanus): correlation with water temperature and photoperiod

1977 ◽  
Vol 55 (5) ◽  
pp. 789-795 ◽  
Author(s):  
G. L. Fletcher
Keyword(s):  
Freezing Point ◽  
Sampling Site ◽  
Winter Flounder ◽  
Day Length ◽  
Freezing Point Depression ◽  
Pseudopleuronectes Americanus ◽  
Annual Cycles ◽  
Sea Floor ◽  
Water And Sediment ◽  
Circannual Cycles

A 4-year field program was conducted on the winter flounder to correlate changes in plasma Na+, Cl−, and freezing-point depression with sea-floor water and sediment temperatures, day length, salinity, depth of capture, and observations on burrowing in sediments.Plasma Na+, Cl−, and freezing-point depression showed annual cycles with maxima in winter (January–April) (temperature −1.1 to −1.4 °C) and minima in summer (July–October) (10–14 °C). The change in freezing-point depression from summer to winter was about 0.65 °C, 20% of this was attributable to Na+ and Cl− and the remaining 80% to the presence of an 'antifreeze.' The data suggest that plasma 'antifreeze' appeared in November (4–6 °C) and disappeared during May (−1.0 to 3 °C). During the winter the flounder were found only in the deeper areas of the sampling site and were usually buried up to 12–15 cm in the sediments which were warmer (0.1 to 0.4 °C) than the seawater.The plasma Na+, Cl−, and freezing-point depression of winter flounder held in the laboratory for 7 days were always significantly lower than the field-sampled fish. The differences between these two groups was greatest during the summer, suggesting that the effects of 'stress' during capture differ seasonaly.

Evidence for permanent population differences in the annual cycle of plasma "antifreeze" levels of winter flounder

1980 ◽  
Vol 58 (4) ◽  
pp. 507-512 ◽  
Author(s):  
G. L. Fletcher ◽  
J. C. Smith
Keyword(s):  
Water Temperature ◽  
Seasonal Changes ◽  
Regional Differences ◽  
Freezing Point ◽  
Winter Flounder ◽  
Population Differences ◽  
Freezing Point Depression ◽  
Plasma Electrolytes ◽  
Nova Scotian ◽  
Two Populations

Seasonal changes in plasma freezing point depression and Cl− concentration in a population of Nova Scotian winter flounder were compared with the seasonal changes which occurred in a population of Newfoundland flounder. The plasma protein "antifreeze" component of the freezing point depression was computed by subtracting the freezing point depression due to the concentration of plasma electrolytes from the total plasma freezing point depression.In Nova Scotian flounder the plasma "antifreeze" level increased approximately 1 month later and declined 2 months earlier than it did in Newfoundland flounder. These differences between the two populations of fish correlated with the regional differences in seawater temperature.When Nova Scotian flounder were transferred to Newfoundland and maintained under Newfoundland conditions of water temperature and photoperiod they retained their plasma "antifreeze" cycle for the duration of the study (approximately 1 year).These results suggest that the timing of the annual plasma "antifreeze" cycle may be a permanent feature of the flounder's physiology and that water temperature does not directly control it. It is hypothesized that some aspects of the annual antifreeze cycle may be endogenous and that if photoperiod plays a role in its regulation the differences between Newfoundland and Nova Scotia are too slight for the cycle to be adjusted in 1 year.

Effects of temperature and photoperiod on the plasma freezing point depression, Cl− concentration, and protein "antifreeze" in winter flounder

1981 ◽  
Vol 59 (2) ◽  
pp. 193-201 ◽  
Author(s):  
G. L. Fletcher
Keyword(s):  
Annual Cycle ◽  
Freezing Point ◽  
Winter Flounder ◽  
Day Length ◽  
Pseudopleuronectes Americanus ◽  
Temperature Dependent ◽  
Influence Of Water ◽  
Effects Of Temperature ◽  
Elevated Water ◽  
Precise Time

The influence of water temperature and photoperiod on the timing of the annual cycle of plasma "antifreeze" and Cl− levels was examined in winter flounder (Pseudopleuronectes americanus).The normal winter appearance of plasma "antifreeze" was delayed by day lengths longer than 12 h. Day length had no effect on the timing of "antifreeze" disappearance in spring.The time of "antifreeze" appearance was delayed by low water temperatures and unaffected by warm water.The rate of "antifreeze" disappearance in the spring was temperature dependent. Flounder continuously exposed to elevated water temperatures during the winter lost the "antifreeze" several months prior to controls.Plasma Cl− concentrations increased with declining seawater temperatures. Long day lengths delayed the time at which this increase normally appeared. A small winter increase in plasma Cl− occurred even when the flounder were exposed to constant conditions of warm water.The results suggest that the annual "antifreeze" cycle may be endogenous with photoperiod being the zeitgeber for entraining the precise time of initiation of "antifreeze" synthesis in the early winter.Several aspects of the plasma Cl− annual cycle may also be under endogenous control.

The effects of long day length on liver antifreeze mRNA in the winter flounder, Pseudopleuronectes americanus

1984 ◽  
Vol 62 (8) ◽  
pp. 1456-1460 ◽  
Author(s):  
Ron M. Fourney ◽  
Garth L. Fletcher ◽  
Choy L. Hew
Keyword(s):  
Blot Hybridization ◽  
Winter Flounder ◽  
Day Length ◽  
Control Fish ◽  
Pituitary Hormone ◽  
Northern Blot Hybridization ◽  
Mrna Levels ◽  
Pseudopleuronectes Americanus ◽  
Long Day ◽  
Afp Mrna

The effect of photoperiod on the seasonal accumulation of winter flounder (Pseudopleuronectes americanus) antifreeze polypeptide (AFP) mRNA in the liver was examined. AFP mRNA levels were identified and measured by cytoplasmic dot hybridization and Northern blot hybridization procedures utilizing a nick-translated antifreeze genomic clone. Flounder maintained under conditions of 15-h long day length have both a delayed appearance and decreased accumulation of AFP mRNA. December flounder maintained under long day length had the most significant decrease in AFP mRNA levels. It was estimated that these fish contained less than 0.6% of the AFP mRNA normally found in control fish. The seasonal fluctuation of AFP mRNA in both the experimental and control fish matched closely but preceded the rise and fall of plasma AFP levels. These results suggest that long day length suppresses the rate of transcription of antifreeze genes and supports the hypothesis that photoperiod may act as the initial cue for entraining the precise activation of AFP synthesis. A pituitary hormone may be the mediator.

Seasonal changes in the plasma levels of glycoprotein antifreeze, Na+, Cl−, and glucose in Newfoundland Atlantic cod (Gadus morhua)

1982 ◽  
Vol 60 (8) ◽  
pp. 1851-1854 ◽  
Author(s):  
G. L. Fletcher ◽  
D. Slaughter ◽  
C. L. Hew
Keyword(s):  
Seasonal Changes ◽  
Gadus Morhua ◽  
Thermal Hysteresis ◽  
Atlantic Cod ◽  
Freezing Point ◽  
Freezing Point Depression ◽  
Antifreeze Glycoproteins ◽  
Glucose Levels ◽  
Total Plasma Protein ◽  
Two Peaks

A seasonal study was carried out on the hematocrits, plasma freezing point depression, and thermal hysteresis, and plasma Na+, Cl−, total protein, and glucose concentrations in laboratory maintained Atlantic cod. Significant thermal hysteresis was evident in the plasma during the months of January to May indicating the presence of antifreeze glycoproteins. Plasma freezing point depression and Na+ and Cl− concentrations were highest during the winter months and lowest during the summer. Two peaks in glucose levels were evident; one in February and the other in July. No seasonal changes were evident in hematocrits and total plasma protein concentrations.

Localization of Anionic Binding Sites in the Glomerular Basement Membrane of a Cold Water Teleost

1982 ◽  
Vol 40 ◽  
pp. 288-289
Author(s):  
R. B. Boyd ◽  
A. L. DeVries
Keyword(s):  
Binding Sites ◽  
Cold Water ◽  
Sea Water ◽  
Freezing Point ◽  
Winter Flounder ◽  
Pseudopleuronectes Americanus ◽  
Anionic Sites ◽  
Glomerular Filtration Barrier ◽  
Filtration Barrier ◽  
Anionic Binding Sites

The blood of the winter flounder, Pseudopleuronectes americanus, a cold water teleost, is characterized by the presence of small (3000-5000d) anionic (pI 4.1-4.5) peptides that lower the freezing point of the blood. These peptides exhibit a seasonal variation, occurring only in the winter when the fish is exposed to temperatures near or below the freezing point of sea water. The antifreeze molecule is retained by the glomerular kidney of the fish even through inulin, of comparable weight, is rapidly filtered from the blood into the urine. We have examined the glomerular filtration barrier in the winter flounder, using the electron-dense ferritins, in order to identify anionic sites that might function to conserve these peptides.

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