A continuum of sleep and shallow torpor in fasting doves

Fasting doves entered shallow torpor during nocturnal sleep. Body temperature dropped lower each successive night by 1 degrees to 3 degrees in parallel with diminished rapid-eye-movement sleep until torpor was composed almost entirely of slow-wave sleep at a body temperature of 30 degrees to 32 degrees C. Shallow torpor in doves, as in mammals, thus appears to lie on a metabolic continuum with sleep.     

Body Temperature of Dermochelys coriacea: Warm Turtle from Cold Water

The deep body temperature of a leatherback turtle, Dermochelys coriacea, taken out of cold water, was 18 degrees C above the water temperature. A large size favoring heat retention from muscular activity is probably responsible for this differential. Cooling rates (k) in water, measured on a second animal, were in the order of 0.001 degrees C per minute per degree of difference between body and ambient temperature.     

Brain and body temperatures in a panting lizard

Panting in Sauromalus obesus is effective enough to keep deep body temperature (T(C)) and brain temperature (T(B)) below an ambient temperature of 45 degrees C for extended periods of time and has a greater cooling effect on the brain than on the remainder of the body. Six animals maintained T(C) and T(B) 0.9 degrees C (+/- 0.08 standard error) and 2.7 degrees C (+/- 0.2 standard error) respectively lower than the ambient temperature of 45 degrees C. It is possible that intracranial vascular shunts play a role in cranial cooling during panting.     

Homeothermic response to reduced ambient temperature in a scarab beetle

Elephant beetles (Megasoma elephas; Scarabaeidae) weighing from 10 to 35 grams, respond homeothermically when ambient temperature is reduced below about 20 degrees C in the laboratory. This metabolic response is not associated with locomotion or any other overt activity. Warming is initiated when the body temperature reaches an apparent set point of 20 degrees to 22 degrees C. Unlike the case for euthermic birds and mammals, energy metabolism and body temperature in these beetles are conspicuously oscillatory, with a given cycle in oxygen consumption peaking before the corresponding cycle in body temperature.     

Temperature Regulation in the Bumblebee Bombus vagans: A Field Study

Bombus vagans forages for nectar at 5 degrees C in shade and at 31 degrees C in sunshine. The production of heat while the bumblebee is on flowers, at ambient temperatures below 24 degrees C, helps to maintain a thoracic temperature that is near the minimum for flight between flowers. However, at ambient temperatures above 24 degrees C the thoracic temperature is no longer regulated at 32 degrees to 33 degrees C and rises.     

Thermoregulation in endothermic insects

On the basis of body weight, most flying insects have higher rates of metabolism, and hence heat production, than other animals. However, rapid rates of cooling because of small body size in most cases precludes appreciable endothermy. The body temperature of small flies in flight is probably close to ambient temperature, and that of flying butterflies and locusts is 5 degrees to 10 degrees C above ambient temperature. Many moths and bumblebees are insulated with scales and hair, and their metabolism during flight can cause the temperature of the flight muscles to increase 20 degrees to 30 degrees C above ambient temperature. Curiously, those insects which (because of size, insulation) retain the most heat in the thorax during flight, also require the highest muscle temperature in order to maintain sufficient power output to continue flight. The minimum muscle temperature for flight varies widely between different species, while the maximum temperature varies over the relatively narrow range of 40 degrees to 45 degrees C. As a consequence, those insects that necessarily generate high muscle temperatures during flight must maintain their thoracic temperature within a relatively narrow range during flight. Active heat loss from the thorax to the abdomen prevents overheating of the flight motor and allows some large moths to be active over a wide range of ambient temperatures. Bumblebees similarly transfer heat from the flight musculature into the abdomen while incubating their brood by abdominal contact. Many of the larger insects would remain grounded if they did not actively increase the temperature of their flight muscles prior to flight. Male tettigoniid grasshoppers elevate their thoracic temperature prior to singing. In addition, some of the social Hymenoptera activate the "flight" muscles specifically to produce heat not only prior to flight but also during nest temperature regulation. During this "shivering" the "flight" muscles are often activated in patterns different from those during flight. The muscles contract primarily against each other rather than on the wings. However, the rate of heat production during shivering and flight is primarily a function of the action potential frequency rather than of the patterns of activation. Thermoregulation is a key factor in the energetics of foraging of some of the flower-visiting insects. The higher their muscle temperature the more flowers they can visit per unit time. When food supplies are ample, bees may invest relatively large amounts of energy for thermoregulation. While shivering to maintain high body temperatures during the short intervals they are perched on flowers (as well as while in the nest), bumblebees often expend energy at rates similar to the rates of energy expenditure in flight. Unlike vertebrates, which usually regulate their body temperature at specific set points, the body temperature of insects is labile. It often appears to be maintained near the lower temperature at which the muscles are able to perform the function at hand. The insects' thermal adaptations may not differ as much from those of vertebrates as previously supposed when size, anatomy, and energy requirements are taken into account.     

Influence of hexane solubles in tobacco on a polycyclic fraction of cigarette smoke

Six rats, working in a 2 degrees C ambient temperature, were trained to depress a lever to receive a brief period of heat. Four rats were then moved into the 2 degrees C environment to live, while the others continued to live at room temperature. Living at a temperature of 2 degrees C increased the number of heat presentations the animals delivered to themselves.     

Feeding and core temperature in albino rats: changes induced by preoptic heating and cooling

At an ambient temperature of 25 degrees C, selective cooling of the area preoptica medialis to 24 degrees +/- 1 degrees C produced a significant decrease in food intake together with hyperthermia. Heating the same area to 43 degrees +/- 1 degrees C resulted in the opposite effects. At an ambient temperature of 35 degrees C, heating the area preoptica medialis to 43 degrees C resulted in a decrease in food intake despite concomitant hypothermia.     

Oyster herpes-type virus

A herpes-type virus infection, the first to be found in an invertebrate animal, is reported in the oyster Crassostrea virginica. Intranuclear herpes-type viral inclusions were more prevalent in the oyster at elevated water temperatures of 28 degrees to 30 degrees C than at normal ambient temperatures of 18 degrees to 20 degrees C. The inclusions were associated with a lethal disease at the elevated temperatures.     

Freeze avoidance in a mammal: body temperatures below 0 degree C in an Arctic hibernator

Hibernating arctic ground squirrels, Spermophilus parryii, were able to adopt and spontaneously arouse from core body temperatures as low as -2.9 degrees C without freezing. Abdominal body temperatures of ground squirrels hibernating in outdoor burrows were recorded with temperature-sensitive radiotransmitter implants. Body temperatures and soil temperatures at hibernaculum depth reached average minima during February of -1.9 degrees and -6 degrees C, respectively. Laboratory-housed ground squirrels hibernating in ambient temperatures of -4.3 degrees C maintained above 0 degree C thoracic temperatures but decreased colonic temperatures to as low as -1.3 degrees C. Plasma sampled from animals with below 0 degree C body temperatures had normal solute concentrations and showed no evidence of containing antifreeze molecules.     

Heat production and temperature regulation in eastern skunk cabbage

The spadix of Symplocarpus foetidus L. maintains an internal temperature 15 degrees to 35 degrees C above ambient air temperatures of -15 degrees to +15 degrees C. For at least 14 days it consumes oxygen at a rate comparable to that of homeothermic animals of equivalent size. Temperature regulation is accomplished by variations in respiratory rate.     

Ross ice shelf sea temperatures

Two temperature profiles recorded by a sensitive bathythermograph at the Ross Ice Shelf Project site (82 degrees 22.5'S, 168 degrees 37.5'W) are presented. From the shape of the profiles it is concluded that an inflow of water at intermediate depths provides a source of heat to drive a regime in which ice is melted from the interface at a depth of 360 meters. Melting maintains the temperature of a thick layer under the ice at about -2.14 degrees C, close to the ambient freezing temperature. A very well mixed layer about 35 meters thick was found at the seabed.     

Keeping a cool head: honeybee thermoregulation

At high ambient temperatures, honeybees regulate head teriperature by evaporative cooling of regurgitated honeycrop contents. Thoracic temperature is secondarily stabilized as heat flows from thorax to head by means of passive conduction and physiological facilitation resulting from accelerated blood flow. The mechanism permits flight at the extraordinarily high ambient temperature of 46 degrees C without overheating the head and thorax despite prodigious amounts of heat produced as a by-product of flight metabolism. In contrast, at low ambient temperatures, thoracic rather than head temperature is regulated; no liquid is regurgitated, and the head is heated passively by conduction both in flight and while stationary.     

Regulation of body temperature in the blue-tongued lizard

Lizards (Tiliqua scincoides) regulated their internal body temperature by moving back and forth between 15 degrees and 45 degrees C environments to maintain colonic and brain temperatures between 30 degrees and 37 degrees C. A pair of thermodes were implanted across the preoptic region of the brain stem, and a reentrant tube for a thermocouple was implanted in the brain stem. Heating the brain stem to 41 degrees C activated the exit response from the hot environment at a colonic temperature 1 degrees to 2 degrees C lower than normal, whereas cooling the brain stem to 25 degrees C delayed the exit from the hot environment until the colonic temperature was 1 degrees to 2 degrees C higher than normal. The behavioral thermoregulatory responses of this ectotherm appear to be activated by a combination of hypothalamic and other body temperatures.     

Effect of Acclimation on the Preferred Body Temperature of the Lizard,Sceloporus occidentalis

The preferred body temperature was determined for several groups of Sceloporus occidentalis previously acclimated to several constant temperature levels. Acclimation to a high temperature (35 degrees C) resulted in the selection of a lowered mean preferred body temperature, whereas acclimation to lower temperatures (12 degrees C and 25 degrees C) produced no change in the preferred body temperature.     

Forebrain temperature activates behavioral thermoregulatory response in arctic sculpins

Arctic sculpins of the genus Myoxocephalus adapted to water at 5 degrees C escaped from warm water at 20 degrees , 16 degrees , and 12 degrees C when their deep-body temperatures increased from an initial 5 degrees C to about 8 degrees C. Heating parts of the forebrain with water at 25 degrees C circulating through a pair of thermodes astraddle rostral parts of the forebrain shortened the time spent in the warm water and lessened the incease in deep-body temperature before exit from the warm water. Cooling the forebrain to about -1 degrees C caused a large increase in the body temperature and sometimes suppressed the escape from the warm water.     

急性热应激对北京油鸡生产性能的影响及Vc添加效应的研究

本试验旨在研究急性热应激对北京油鸡生长速度、肉品质以及抗病力的影响及日粮中添加Vc对缓解热应激的效果.试验在人工环控气候舱里进行.选取体重相近的56日龄北京油鸡公鸡162只,随机分为3个处理:Ⅰ为饲喂基础日粮的适温对照组;Ⅱ为饲喂基础日粮的高温应激组;Ⅲ为基础日粮中添加200 mg·kg-1的高温应激组.热应激1周后,所有处理统一饲喂基础日粮,环境温度维持在28℃.研究结果显示,急性热应激引起北京油鸡生长速度减慢,日增重降低,并且这种应激效应持续到上市日龄,表现在上市体重显著低于非热应激组(P＜0.01);热应激导致鸡群死亡率上升,且抗体合成能力下降;热应激期间日粮中添加200 mg·kg-1有利于增强鸡的免疫力,且对鸡肉的pH值、肌内脂肪含量等品质性状产生一定的影响.     

New phases of c60 synthesized at high pressure

The fullerene C(60) can be converted into two different structures by high pressure and temperature. They are metastable and revert to pristine C(60) on reheating to 300 degrees C at ambient pressure. For synthesis temperatures between 300 degrees and 400 degrees C and pressures of 5 gigapascals, a nominal face-centered-cubic structure is produced with a lattice parameter a(o) = 13.6 angstroms. When treated at 500 degrees to 800 degrees C at the same pressure, C(60) transforms into a rhombohedral structure with hexagonal lattice parameters of a(o) = 9.22 angstroms and c(o) = 24.6 angstroms. The intermolecular distance is small enough that a chemical bond can form, in accord with the reduced solubility of the pressure-induced phases. Infrared, Raman, and nuclear magnetic resonance studies show a drastic reduction of icosahedral symmetry, as might occur if the C(60) molecules are linked.     

Visceral tissue vascularization: an adaptive response to high temperature

Electrical heat sources implanted in the abdominal cavities of sheep were heated to give initial temperatures of 42 degrees and 45 degrees C at the surfaces of the heaters. During 18 days of constant heating, a vascularized connective-tissue envelope encapsulated the heat sources, and the temperatures at the surfaces of the heaters declined 0.8 degrees and 1.8 degrees C, respectively. The degree of vascularization and the magnitude of the decrease in the surface temperature appeared to be related to the proximity of the tissue's initial temperature to 45 degrees C, a temperature ordinarily considered detrimental to cell structure. The vascularization thus appears to be adaptive.     

白条锦蛇耗氧量和耗氧率

测定了5种温度(14 、17、 20、 24和29℃)下,白条锦蛇的耗氧量及耗氧率.结果表明:在这5种温度条件下,白条锦蛇的耗氧量均随体质量的增加而明显增大,而白条锦蛇的耗氧率则刚好相反,随体质量的增加耗氧率反而减小; 另外,白条锦蛇的耗氧量、耗氧率与温度均呈显著的线性回归关系.在14～29℃白条锦蛇的耗氧量、耗氧率均随温度升高而增加,并得出耗氧量x0与温度t的一元线性回归方程:x0=-25.25+3.51t,耗氧率Q0与温度t的一元线性回归方程Q0=-230.25+27.14t.白条锦蛇的耗氧率与温度的变化关系,说明白条锦蛇的新陈代谢率随环境温度改变而改变,在14～29℃白条锦蛇的新陈代谢随环境温度升高而加快.