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• 1. [Article] Effects of dehydration on hemoglobin oxygen affinity and blood cell volume in two anurans

  Two aspects of possible adaptation In cardiovascular performance caused by Increased plasma electrolytes were examined. Cells In anisotonic plasma may either act as osmometers or volume regulate. Blood ...

  Citation × Citation Citation Abstract Copy Title: Effects of dehydration on hemoglobin oxygen affinity and blood cell volume in two anurans Author: Zygmunt, Andrew Christopher Year: 1984 Two aspects of possible adaptation In cardiovascular performance caused by Increased plasma electrolytes were examined. Cells In anisotonic plasma may either act as osmometers or volume regulate. Blood flow rate Is dependent upon cell viscosity, which in turn is a consequence of cell volume and membrane deform-ability. Cell volume changes which Increase membrane deform-ability will thus potentially extend the limits of dehydration tolerance. It was found in R. catesbeiana and B. marinus that red blood cell Is maintain constant volume during dehydration. Cells in vitro Initially lose water, but then sodium, potassium and water move Into the cell. Cell viscosity within the physiologic range of hematocrits was higher In salt loaded non-regulating cell Is of B. marinus than In regulating isotonic cells. Title: Effects of dehydration on hemoglobin oxygen affinity and blood cell volume in two anurans Author: Zygmunt, Andrew Christopher Year: 1984 Two aspects of possible adaptation In cardiovascular performance caused by Increased plasma electrolytes were examined. Cells In anisotonic plasma may either act as osmometers or volume regulate. Blood flow rate Is dependent upon cell viscosity, which in turn is a consequence of cell volume and membrane deform-ability. Cell volume changes which Increase membrane deform-ability will thus potentially extend the limits of dehydration tolerance. It was found in R. catesbeiana and B. marinus that red blood cell Is maintain constant volume during dehydration. Cells in vitro Initially lose water, but then sodium, potassium and water move Into the cell. Cell viscosity within the physiologic range of hematocrits was higher In salt loaded non-regulating cell Is of B. marinus than In regulating isotonic cells. Close

• 2. [Article] The metabolic cost of behavioral thermoregulation of body temperature in the northern alligator lizard Gerrhonotus coeruleus, and how it affects the classical concept of eurythermality

  The effect of total metabolic cost expenditures on the precision of behavioral thermoregulation was investigated for the purportedly eurythermic Northern Alligator lizard (Gerrhonotus coeruleus). An operant ...

  Citation × Citation Citation Abstract Copy Title: The metabolic cost of behavioral thermoregulation of body temperature in the northern alligator lizard Gerrhonotus coeruleus, and how it affects the classical concept of eurythermality Author: Campbell, James Dudley Year: 1981 The effect of total metabolic cost expenditures on the precision of behavioral thermoregulation was investigated for the purportedly eurythermic Northern Alligator lizard (Gerrhonotus coeruleus). An operant apparatus was designed to test metabolic output at different heat reinforcement magnitudes. The mean TB reflected in each trial was positively correlated to the length of reinforcement. The shuttle rate during each trial was inversely correlated to the length of reinforcement. The standard deviation and total metabolic costs did not vary significantly between trials undertaken at the same ambient temperature. Eurythermality in G. coeruleus is caused by fluctuations in preferred body temperature and not by fluctuations around this temperature. The metabolic cost of behavioral thermoregulation did not change with corresponding changes in reinforcement magnitude. This indicates that eurythermality is the recorded effect of lizards behaviorally regulating to different TB in a stenothermic manner, rather than of random TB fluctuations in a wide range of normal activity (the classical view of eurythermality). Title: The metabolic cost of behavioral thermoregulation of body temperature in the northern alligator lizard Gerrhonotus coeruleus, and how it affects the classical concept of eurythermality Author: Campbell, James Dudley Year: 1981 The effect of total metabolic cost expenditures on the precision of behavioral thermoregulation was investigated for the purportedly eurythermic Northern Alligator lizard (Gerrhonotus coeruleus). An operant apparatus was designed to test metabolic output at different heat reinforcement magnitudes. The mean TB reflected in each trial was positively correlated to the length of reinforcement. The shuttle rate during each trial was inversely correlated to the length of reinforcement. The standard deviation and total metabolic costs did not vary significantly between trials undertaken at the same ambient temperature. Eurythermality in G. coeruleus is caused by fluctuations in preferred body temperature and not by fluctuations around this temperature. The metabolic cost of behavioral thermoregulation did not change with corresponding changes in reinforcement magnitude. This indicates that eurythermality is the recorded effect of lizards behaviorally regulating to different TB in a stenothermic manner, rather than of random TB fluctuations in a wide range of normal activity (the classical view of eurythermality). Close

• 3. [Article] Effect of ethanol on thermoregulation in the goldfish, Carassius auratus

  In an attempt to elucidate the mechanism by which ethanol affects vertebrate thermoregulation, the effect of ethanol on temperature selection was studied in the goldfish, Carassius auratus. Ethanol was ...

  Citation × Citation Citation Abstract Copy Title: Effect of ethanol on thermoregulation in the goldfish, Carassius auratus Author: O'Connor, Candace Sharon Year: 1986 In an attempt to elucidate the mechanism by which ethanol affects vertebrate thermoregulation, the effect of ethanol on temperature selection was studied in the goldfish, Carassius auratus. Ethanol was administered to 10 to 15 g fish by mixing it in the water of a temperature gradient. The dose response curve was very steep between 0.5% (v/v) ethanol (no response) and 0.7% (significant lowering of selected temperature in treated fish). Fish were exposed to concentrations of ethanol as high as 1.7%, at which concentration most experimental fish lost their ability to swim upright in the water. At concentrations higher than 0.7%, the magnitude of the effect did not increase with increasing concentration of ethanol; treated animals continued to select temperatures about 2 C below temperatures selected by controls. Experiments alternating exposure to 1.0% ethanol and water showed that the rate of onset and disappearance of the ethanol effect was rapid (within 10 min). Other experiments exposing fish to 1.0% ethanol for up to 3 hr showed that the effect remained stable for this period of time. The thermoregulatory responses of fish are behavioral, and therefore relatively easy to observe and quantify. Ethanol produces a prompt, stable and reproducible depression of selected temperature in the goldfish. Because the temperature at which fish regulate is controlled by a central nervous system set point and not altered by effects on peripheral effector systems, it appears that ethanol may cause hypothermia in goldfish by directly acting to lower the set point. Title: Effect of ethanol on thermoregulation in the goldfish, Carassius auratus Author: O'Connor, Candace Sharon Year: 1986 In an attempt to elucidate the mechanism by which ethanol affects vertebrate thermoregulation, the effect of ethanol on temperature selection was studied in the goldfish, Carassius auratus. Ethanol was administered to 10 to 15 g fish by mixing it in the water of a temperature gradient. The dose response curve was very steep between 0.5% (v/v) ethanol (no response) and 0.7% (significant lowering of selected temperature in treated fish). Fish were exposed to concentrations of ethanol as high as 1.7%, at which concentration most experimental fish lost their ability to swim upright in the water. At concentrations higher than 0.7%, the magnitude of the effect did not increase with increasing concentration of ethanol; treated animals continued to select temperatures about 2 C below temperatures selected by controls. Experiments alternating exposure to 1.0% ethanol and water showed that the rate of onset and disappearance of the ethanol effect was rapid (within 10 min). Other experiments exposing fish to 1.0% ethanol for up to 3 hr showed that the effect remained stable for this period of time. The thermoregulatory responses of fish are behavioral, and therefore relatively easy to observe and quantify. Ethanol produces a prompt, stable and reproducible depression of selected temperature in the goldfish. Because the temperature at which fish regulate is controlled by a central nervous system set point and not altered by effects on peripheral effector systems, it appears that ethanol may cause hypothermia in goldfish by directly acting to lower the set point. Close

• 4. [Article] Factors affecting thyrotropin secretion in superfused rat anterior pituitary cells

  The use of static in vitro pituitary cultures has been indispensible for examining the regulation of anterior pituitary hormone secretion. While the static cultures have shown the effects of various chemical ...

  Citation × Citation Citation Abstract Copy Title: Factors affecting thyrotropin secretion in superfused rat anterior pituitary cells Author: Bartlow, Frederick Scott Year: 1982 The use of static in vitro pituitary cultures has been indispensible for examining the regulation of anterior pituitary hormone secretion. While the static cultures have shown the effects of various chemical stimulators of hormone secretion, the dynamics of such secretion has not been assessed before in vitro. The in vitro superfusion method, which partially stimulates in vivo physiologic conditions, allows for the observation of the dynamics of pituitary hormone secretion. Title: Factors affecting thyrotropin secretion in superfused rat anterior pituitary cells Author: Bartlow, Frederick Scott Year: 1982 The use of static in vitro pituitary cultures has been indispensible for examining the regulation of anterior pituitary hormone secretion. While the static cultures have shown the effects of various chemical stimulators of hormone secretion, the dynamics of such secretion has not been assessed before in vitro. The in vitro superfusion method, which partially stimulates in vivo physiologic conditions, allows for the observation of the dynamics of pituitary hormone secretion. Close

• 5. [Article] Decrease in selected temperature after intracranial dopamine injections in goldfish

  Goldfish (Carassius auratus) (40-80g) were injected with dopamine into the forebrain to study the possible involvement of this amine in central temperature regulation in these fish. Dopamine caused a decrease ...

  Citation × Citation Citation Abstract Copy Title: Decrease in selected temperature after intracranial dopamine injections in goldfish Author: Panayiotides-Djaferis, Hercules Theodore Year: 1987 Goldfish (Carassius auratus) (40-80g) were injected with dopamine into the forebrain to study the possible involvement of this amine in central temperature regulation in these fish. Dopamine caused a decrease in selected temperature after injection into the rostral nucleus preopticus periventricularis (NPP). This effect was dependent on the dose of dopamine administered. Doses of 25, 50, 100 and 250 ng were used, injected in a volume of 0.2μ1. Injections in regions adjacent to the NPP elicited hypothermic effects only at the higher dosages. These effects were not consistent. Injections in caudal regions of the NPP elicited no effect. The effects of dopamine were blocked by haloperidol, a selective antagonist of dopamine. It is suggested that dopamine acts on central thermoregulatory neurons, present in the rostral NPP, in the mediation of thermoregulatory behavior. Further, it is suggested that this action is mediated via dopaminergic receptors. Title: Decrease in selected temperature after intracranial dopamine injections in goldfish Author: Panayiotides-Djaferis, Hercules Theodore Year: 1987 Goldfish (Carassius auratus) (40-80g) were injected with dopamine into the forebrain to study the possible involvement of this amine in central temperature regulation in these fish. Dopamine caused a decrease in selected temperature after injection into the rostral nucleus preopticus periventricularis (NPP). This effect was dependent on the dose of dopamine administered. Doses of 25, 50, 100 and 250 ng were used, injected in a volume of 0.2μ1. Injections in regions adjacent to the NPP elicited hypothermic effects only at the higher dosages. These effects were not consistent. Injections in caudal regions of the NPP elicited no effect. The effects of dopamine were blocked by haloperidol, a selective antagonist of dopamine. It is suggested that dopamine acts on central thermoregulatory neurons, present in the rostral NPP, in the mediation of thermoregulatory behavior. Further, it is suggested that this action is mediated via dopaminergic receptors. Close

• 6. [Article] Norepinephrine and temperature regulation in goldfish

  Cannulae were implanted into forebrain loci of goldfish (Carassius auratus; 45-90 g) to determine (i) the effects and site of action of intracranial norepinephrine (NE) injections on behavioral thermoregulation ...

  Citation × Citation Citation Abstract Copy Title: Norepinephrine and temperature regulation in goldfish Author: Wollmuth, Lonnie Paul Year: 1987 Cannulae were implanted into forebrain loci of goldfish (Carassius auratus; 45-90 g) to determine (i) the effects and site of action of intracranial norepinephrine (NE) injections on behavioral thermoregulation and (ii) the mechanism and the types of adrenoreceptors involved in the thermoregulatory effect of NE. After 30 min in a thermal gradient, implanted fish were injected with norepinephrinebitartrate salt (2.5-500 ng NE) in a total volume of 0.2 ul (carrier was 0.7% NaCl). Injections of 5, 10, 25, and 50 ng NE into the anterior aspect of the nucleus preopticus periventricularis (NPP1 Peter and Gill 1975) led to consistent, dose-dependent decreases in selected temperature. No effect on temperature selection was observed following injections of 2.5 ng NE or control injections of 100 ng tartaric acid. The effects of injections into other loci, including intraventricular injections, were dependent upon the dose and proximity to the anterior NPP1 at sites adjacent to the anterior NPP, larger doses were required, and the effects became inconsistent. At sites further removed, no effect on selected temperature was observed1 included in this category were more caudal sites within the NPP and the nucleus preopticus. Title: Norepinephrine and temperature regulation in goldfish Author: Wollmuth, Lonnie Paul Year: 1987 Cannulae were implanted into forebrain loci of goldfish (Carassius auratus; 45-90 g) to determine (i) the effects and site of action of intracranial norepinephrine (NE) injections on behavioral thermoregulation and (ii) the mechanism and the types of adrenoreceptors involved in the thermoregulatory effect of NE. After 30 min in a thermal gradient, implanted fish were injected with norepinephrinebitartrate salt (2.5-500 ng NE) in a total volume of 0.2 ul (carrier was 0.7% NaCl). Injections of 5, 10, 25, and 50 ng NE into the anterior aspect of the nucleus preopticus periventricularis (NPP1 Peter and Gill 1975) led to consistent, dose-dependent decreases in selected temperature. No effect on temperature selection was observed following injections of 2.5 ng NE or control injections of 100 ng tartaric acid. The effects of injections into other loci, including intraventricular injections, were dependent upon the dose and proximity to the anterior NPP1 at sites adjacent to the anterior NPP, larger doses were required, and the effects became inconsistent. At sites further removed, no effect on selected temperature was observed1 included in this category were more caudal sites within the NPP and the nucleus preopticus. Close

• 7. [Article] Nitrogen and iron interactions in filamentous cyanobacteria

  The investigations described in this paper are an attempt to further define and quantify the interrelationship of nitrogen fixation and iron nutritional physiology in these two species. Chapter II will ...

  Citation × Citation Citation Abstract Copy Title: Nitrogen and iron interactions in filamentous cyanobacteria Author: Hutchins, David Allen Year: 1989 The investigations described in this paper are an attempt to further define and quantify the interrelationship of nitrogen fixation and iron nutritional physiology in these two species. Chapter II will present and compare data on nutritional ratios of field collected Trichodesmium colonies and laboratory Anabaena cultures, with the intent of examining possible correlations between observed iron levels and protein nitrogen and chlorophyll concentrations, as well as nitrogen fixation rates. Chapter Ill is an examination of nitrogen fixation and siderophore production in Anabaena with emphasis on the possible implications of hypothesized synergistic effects of these two physiological capabilities on cyanobacterial dominance and bloom formation. Chapter IV will deal with the possibility of gratuitous manganese repression of Anabaena siderophore production in the manner described by Hantke (1987) for regulation of siderophore production in E. coli. The Conclusions chapter (Chapter V) will present a discussion of the results of these experiments in the context of current problems in cyanobacterial physiology, ecology and evolution. It is hoped that a significant contribution can be made to our understanding of the related problems of cyanobacterial dominance in freshwater ecosysytems and the scarcity of cyanobacterial nitrogen fixation in marine ecosystems. Title: Nitrogen and iron interactions in filamentous cyanobacteria Author: Hutchins, David Allen Year: 1989 The investigations described in this paper are an attempt to further define and quantify the interrelationship of nitrogen fixation and iron nutritional physiology in these two species. Chapter II will present and compare data on nutritional ratios of field collected Trichodesmium colonies and laboratory Anabaena cultures, with the intent of examining possible correlations between observed iron levels and protein nitrogen and chlorophyll concentrations, as well as nitrogen fixation rates. Chapter Ill is an examination of nitrogen fixation and siderophore production in Anabaena with emphasis on the possible implications of hypothesized synergistic effects of these two physiological capabilities on cyanobacterial dominance and bloom formation. Chapter IV will deal with the possibility of gratuitous manganese repression of Anabaena siderophore production in the manner described by Hantke (1987) for regulation of siderophore production in E. coli. The Conclusions chapter (Chapter V) will present a discussion of the results of these experiments in the context of current problems in cyanobacterial physiology, ecology and evolution. It is hoped that a significant contribution can be made to our understanding of the related problems of cyanobacterial dominance in freshwater ecosysytems and the scarcity of cyanobacterial nitrogen fixation in marine ecosystems. Close