published_or_final_version / Community Medicine / Master / Master of Philosophy

published_or_final_version / Zoology / Master / Master of Philosophy

Cyclic AMP-dependent protein kinase (cAMP-PK) is an important mediator of hormone action. Its activity ratio is an accurate indicator of cellular activity under various experimental conditions including: (1) age and sex, (2) hormone administration and (3) temperature and photoperiod. Pituitary activity in unstimulated birds is not altered by age, but thyroid activity is much higher in old birds than in young animals. Thyrotropin releasing hormone (TRH) increases pituitary, thyroid and liver activity of prepubescent chickens, but has no effect on aged males and increases only thyroid and liver activities in aged females, suggesting a reduction in pituitary-thyroid function with advancing age. In prepubertal females, TRH increases pituitary and thyroid cAMP-PK activity, plasma T₃ and T₄ levels and liver T₄ monodeiodination. Thyroid activity reaches maximum activity before the pituitary, while plasma T₄ and liver T₄ monodeodinating activity reach their highest levels 20 minutes before plasma T₃. These findings suggest that fluctuations in liver T₄ 5' monodeiodinating activity might be responsible for the cyclic response of plasma T₃ and T₄. Castrated cockerels have larger pituitaries than untreated birds, but contain the same amount of DNA. Methimazole-fed cockerels have pituitaries significantly smaller than controls, while castrated cockerels fed methimazole have pituitaries the same size as untreated birds. Pituitary DNA is less than controls in both groups of methimazole-fed birds. These results are considered to be due to a change in the thyrotroph population, without an increase in total cell numbers, and may indicate a transformation of basophils. Pituitary cAMP-PK activity during cold stress substantiates this conclusion. Thyroid glands of castrated and untreated cockerels are smaller in size, histological appearance and DNA content; however, cAMP-PK activity is much greater in the castrated birds. Methimazole-fed cockerels have enlarged thyroid glands, elevated cAMP-PK activity, increased DNA and cellular hypertrophy; however, these effects may be mitigated by castration. Seven days after removal of testosterone supplements, photostimulated castrates have a higher thyroid cAMP-PK activity ratio than short day castrates; however, both groups are elevated above control, suggesting that long photoperiods enhance the stimulatory effects of castration on thyroid activity. Pituitary activity is elevated in long and short day birds seven days after removal of testosterone, but remains high only in short day castrates. Therefore, a reduction in the sensitivity of the hypothalamic-pituitary axis to testosterone may occur only in long day cockerels.

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The influence of caffeine on the metabolic and catecholamine responses to mild exercise in a cold and a warm environment was studied in eight healthy males. The subjects performed 60 minutes of cycling at 50% VO2max in a cold environment (5°C and 70% relative humidity) and a warm environment (28°C and 50% relative humidity) 30 minutes after ingesting caffeine (5mg/kg body weight) or placebo (dextrose). Caffeine ingestion prior to exercise in the warm environment resulted in increased plasma epinephrine, with no effect on plasma norepinephrine. Neither lipid nor carbohydrate metabolism was altered by caffeine in the warm trial. Exercise in the cold environment (placebo) produced increased oxygen consumption and carbohydrate metabolism, decreased lipid metabolism, and no difference in plasma catecholamines compared with the warm-placebo trial. Responses to the combination of caffeine ingestion and the cold environment did not differ from cold-placebo responses in oxygen consumption or respiratory exchange ratio during the cycling bout. However, in the cold-caffeine trial plasma epinephrine was elevated. In addition, fat oxidation, serum free fatty acids, and serum glycerol were elevated in the cold-caffeine condition. Carbohydrate oxidation was depressed, while serum glucose and blood lactate were elevated in this trial. The results of this study indicate that caffeine increases plasma epinephrine; cold increases oxygen consumption and carbohydrate metabolism, while decreasing lipid metabolism; and the combination of caffeine and cold during exercise increases plasma epinephrine and lipid metabolism, but decreases carbohydrate metabolism. / Human Performance Laboratory

viii, 88 leaves : ill. ; 29 cm Notes Typescript (Another copy on microfilm is located in Archives) Thesis (M.A.)--University of Oregon Includes vita Bibliography: leaves 83-88

This study examined the extent to which physiological and psychological concomitants of aerobic terrestrial performance were affected by body cooling of varying degrees induced by cold water immersion (CWI). Thirteen male and 13 female subjects underwent three randomly assigned 30 min treadmill runs: a control run without prior manipulation of the subjects' thermal status and the same exercise after "central" (core temperature 1°C below pre-immersion) and "peripheral" cooling (skin heat loss 100kcal.m⁻².h⁻¹). During treadmill runs core temperature was measured, together with chest, leg, arm and hand temperatures, from which mean skin temperature (T [subscript]s[subscript]k) and mean body temperature (T[subscript]b) were calculated. Heart rate, oxygen consumption (VO₂,), carbon dioxide production (VCO₂), minute ventilation (V₂ (BTPS)), breathing frequency (f), cadence and ratings of perceived exertion (RPE) and thermal sensation (PTS) were also measured. Both central and peripheral cooling resulted in significantly reduced T[subscript]r[subscript]e (males : control 37.9±0. 3°C; central cooling : 36.8±0.5°C; peripheral cooling: 37.5±0.4°C; females: control: 37.9±0.4°C; central cooling: 37.2±0.5; p<0.05) during subsequent treadmill running, except following peripheral cooling for females (37.9±0.3°C) . For males and females T[subscript]s[subscript]k was lower following peripheral cooling than control values and lowest after central cooling (males: control: 30.0±1.3°C; central cooling: 36.8±0.5°C; peripheral cooling: 37.5±0.4°C; females: control: 30.5±1.2°C; central cooling: 25.9±1.8°C; peripheral cooling: 26.9±1.9°C; p<0.05). Female subjects experienced significantly higher T[subscript]r[subscript]e than males following central and peripheral cooling and a lower T[subscript]s[subscript]k following central cooling. Females experienced less of an increase in heart rate than males during exercise following central and peripheral cooling (control: l57.7±23.7b.min⁻¹; central cooling: 143.5±20.5b.min⁻¹; peripheral cooling 151.7±16.7b.min⁻¹; p<0 .05). Male responses were the same following central cooling but higher for peripheral cooling than control values (control: 139.1±7.3b.min⁻¹; central cooling 134.7±17.5b.min⁻¹; peripheral cooling: 145.0±16.4b.min⁻¹; p<0.05). These data indicate a depression in cardiovascular function for females following peripheral cooling that was not apparent for males. The VO₂ was not different between tests for males; only peripheral cooling resulted in a raised VO₂ of 28.6±3 .3ml.kg⁻¹.min⁻¹ (p<0 .05) for females compared to 27.6±2.6ml.kg⁻¹.min⁻¹ (control). A biphasic response was evident for VO₂ VCO₂ and V[subscript]B (BTPS). For both sexes overall RPE was lower for peripheral cooling (males: 9.4±1.9; females: 8.7±1.3; p<0 .05) than for control and central cooling. Central RPE was only changed for females following peripheral cooling. Changes in cadence and step length together with the effect of low skin and leg temperatures resulted in higher local RPE for females after central cooling (9.6±1.2; p<0.05) than control (9.4±1.9) and peripheral cooling (8.9±1.2 ). Males and females rated the same ambient temperature during the same exercise lower after peripheral cooling (males: 4.6±1.5; females : 5.3±1.3) than control values and lower still after central cooling (males: 3. 8±1.8; females: 2 .7±l. 5) In this study T[subscript]s[subscript]k was the primary determinant of PTS after precooling. / KMBT_363 / Adobe Acrobat 9.54 Paper Capture Plug-in

Apparatus has been designed and developed for determining the response of the plankton Crustacean Simocephalus serrulatus (Koch) to horizontal gradients of light and temperature. These factors were varied independently or combined under standardized conditions. The temperature preferendum for this organism, cultured in a constant environment, was found to be 19.13°C, for animals previously held at 19°C. for 14 hours. The steepness of a temperature gradient was shown to influence the rate of aggregation at a preferendum temperature. At a constant temperature (temperature preferendum) reactions to light were then studied. Light intensity, gradients of light intensity, light quality, and gradients of light quality were considered. Animals were positively phototactic to the range of visible light intensities considered, but became indifferent to light on the addition of chemical substances to the water medium. An absolute optimum light intensity was demonstrated, at which the response to light is greatest in magnitude. The rate of rise of light intensity was shown to be directly related to the magnitude of the response and indirectly related to the time for the response to reach a peak up to the absolute optimum light intensity. The intensity of illumination was inversely related to the time for adaptation to occur. The magnitude of the light response was inversely related to the intensity of a pre-adaptation light stimulus. Wave lengths in the region of 3000 to 3500 Å, with a mean value of approximately 3300 Å, were shown to reverse the primary sign of the phototactic response. The spectral sensitivity curve for the positive phototactic response to visible light extended from 4000 to 6400 Å. Finally, light factors were applied to the animals in a temperature gradient and quantitative data on the response obtained. The interaction of the two factors produced a response which is the resultant of the factors acting in opposition. / Science, Faculty of / Zoology, Department of / Graduate

The ecology of Cheimophila salicella Hbn. (Lepidoptera: Oecophoridae), a blueberry leaf-tier was studied on high-bush blueberry, Vaccinium corymbosum L., in Richmond, British Columbia. The females frequently laid their eggs in the lichen Xanthoria sp., an oviposition site not previously reported for this species. The possible microclimatic advantages of such behaviour are discussed. In the Field, females required longer than males to complete their 6th instar, so females were usually bigger than males in that instar. The leaf shelter made by the larvae modified their microenvironment in the field. On clear and sunny days, measurements of shelter temperature were 6-7°C above those of ambient air. The shelter temperature remained warmer than the air as long as the incoming radiation levels were high. As the radiation levels dropped, the shelter temperature fell to, or a little below, air temperature. On cloudy days, there was no significant difference between the daily maximum shelter and air temperatures. Under clear skies, the daily amplitude of temperature fluctuations was greater inside the shelter than outside. A laboratory investigation of the effects of such fluctuations on development showed that a large amplitude increased the developmental rate of the lst-4th instars. This increase in rate of development was probably due to an accumulation of extra thermal units (Yeargan 1980) occurring in the large-amplitude regime. However, the high temperature of this regime retarded pupation, and the later instars required longer to complete their development. Overall, larvae in the small and large amplitude regimes required the same amount of time to develop from hatching to pupation. A third regime, "medium amplitude", slowed larval development, probably because the length of its thermophase was longer than that which the insect normally encountered in the field. Fifth- and sixth-instar females took longer than males to complete their development, both in the laboratory and in the field. The larger amplitude regime produced heavier pupae; females were, on average, 12.7 mg heavier than males. The microclimate of the shelter provides the larvae with more degree-days than if they were subjected to ambient air and therefore promotes faster development. Without the extra degree-days provided by the shelter, C. salicella would not be able to complete its larval development before the first lethal autumn frost. / Land and Food Systems, Faculty of / Graduate

Behavior is qualitatively and quantitatively modified by the environment. Thus, any consideration of behavior must take into consideration the environmental conditions present. The present study evaluates the interrelationship between one environmental condition (temperature) and a measurable behavioral phenomenon (territoriality).