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.     

Thermoregulation in the desert iguana Dipsosaurus dorsalis

The body temperature of desert iguanas implanted with miniature temperature-sensitive radio transmitters was continuously monitored in their natural habitat. Extensive thermoregulatory behavior occurred in retreat burrows prior to morning emergence. Such behavior permits the igluana to emerge from below ground at its preferred body temperature rather than suboptimal temperature at which activity in the burrow is initiated.     

啮齿动物的嗅觉识别与配偶选择

嗅觉识别在哺乳动物尤其是啮齿类动物中有重要意义.个体可以通过嗅闻化学信号物质(信息素)而获得其它个体特征信息.成年个体对异性个体的气味识别将影响其配偶选择.     

日光温室生产作业机械及配套设施

日光温室生产作业机械及配套设施是现代农业的重要装备之一,是农机技术与园艺技术相结合的产物。应用设施农业与温室生产机械化技术,能大幅度提升可控条件下的集约化、高效化生产经营水平,将人们从繁重的体力劳动中解放出来,保证作物稳产高产,显著地提高农业整体效益,促进农业经济协调发展。目前,我国推广和使用的日光温室生产作业机械及配套设施有以下几种。     

太阳能加热与锅炉加热对温室温度调节的比较

文章以维持温室最冷月夜间温度12℃以上为目标,研究比较了太阳能加热系统和传统加热系统对温室温度的调节原理和调节效果.太阳能加热系统的热交换器为光管散热器,分为两组,分别悬挂在空中和埋设在地下,用于温室的空气加温和地面的蓄热加温.白天,悬挂在空中的热交换器吸收温室多余能量,通过埋在地下的热交换器将其储存在地下;夜间,储存在地下的热能通过热交换器重新释放出来加热温室空气.传统加热系统的热源为一台15kW的锅炉.实验结果表明:太阳能加热系统在12月至次年1月的最冷几天中供热量不能满足温室作物的需求,但在其它时间,相比传统加热系统更有利于温室环境的调节.因为这种加热系统不仅可用于夜间加热,而且还能避免白天温室内过高温度影响植物生长.这套太阳能加热系统每年能为温室提供360kWh/m2的热量,可节省大量的化石燃料.如果突尼斯国内1400公顷温室全部采用这种加热系统,每年可节约化石燃料5×109kWh.     

Thermoregulation in a brooding female Indian python, Python molurus bivittatus

At varying environmental temperatures, measurements of body temperatures and gas exchange of a female Indian python (Python molurus bivittatus) show that during the brooding period this animal can regulate its body temperature by physiological means analogous to those in endotherms. Ambient temperatures below 33 degrees C result in spasmodic contractions of the body musculature with a consequent increase in metabolism and body temperature.     

Mate selection and the evolution of highly polymorphic self/nonself recognition genes

Multicellular organisms use the products of highly polymorphic genes to distinguish self from conspecific nonself cells or tissues. These allorecognition polymorphisms may regulate somatic interactions between hosts and pathogens or between competitors (to avoid various forms of parasitism), as well as reproductive interactions between mates or between gametes (to avoid inbreeding). In both cases, rare alleles may be advantageous, but it remains unclear which mechanism maintains the genetic polymorphism for specificity in self/nonself recognition. Contrary to earlier reports, we show that mate selection cannot be a strong force maintaining allorecognition polymorphism in two colonial marine invertebrates. Instead, the regulation of intraspecific competitive interactions appears to promote the evolution of polymorphisms in these species.     

馆藏结构与读者需求行为分析

通过对图书馆馆藏结构与读者需求的变化和特点进行分析,认为数字化文献应与印刷型文献协调发展;信息系统服务平台建设应与资源建设同步;必须积极构建图书馆数字化文献服务体系。     

Behavioral regulation of the milieu interne in man and rat

In regulating the internal homeostatic environment mammals, by necessity, employ behavioral strategies that differ from the tactics used in coping with contingencies in the external environment. When an animal consumes a meal, the palatability of that meal is automatically adjusted in accordance with the ultimate internal effects of that meal. If the meal causes toxicosis, the animal acquires an aversion for the taste of the meal; conversely, if recuperation follows ingestion of the meal, the taste of that meal is enhanced. Unlike the learning that occurs when externally referred visual and auditory signals are followed by punishment in the form of peripheral pain or reward in the form of food in the mouth, conditioning to the homeostatic effects of food can occur in a single trial and rarely requires more than three to five trials, even though the ultimate effects of the meal are delayed for hours. Paradoxically, the animal need not be aware of the ultimate internal effect in the same sense that it is aware of external contingencies. For example, an aversion can be acquired even if the animal is unconscious when the agent of illness is administered. Thus, the way in which food-effects are stored in memory may be fundamentally different from the way in which memories of specific time-space strategies devised for external contingencies are stored. This separation of function is indicated by limbic lesions which disrupt conditioning to a buzzer that is followed by shock and facilitate conditioning to a taste that is followed by illness. Operationally speaking, one can describe both aversion conditioning and buzzer-shock conditioning in the spacetime associationistic terms of classical conditioning. However, psychologically speaking, one must realize that in aversion conditioning the animal does not act as if it were acquiring an "if-then" strategy. It acts as if a hedonic shift, or a change in the incentive value of the flavor were taking place. Such hedonic shifts are critical in regulation of the internal milieu. When an animal is in need of calories, food tends to be more palatable; as the caloric deficit is restored, food becomes less palatable. If the animal's body temperature is below optimum, a warm stimulus applied to the skin is pleasant. When body temperature is too high, the converse is true. In this way, homeostatic states monitored by internal receptors produce changes in the incentive values of external stimuli sensed by the peripheral receptors, and guide feeding behavior. In mammals at least, the gustatory system, which provides sensory control of feeding, sends fibers to the nucleus solitarius. This brainstem relay station also receives fibers from the viscera and the internal monitors of the area postrema. Ascending fibers bifurcate at the level of the pons and project toward the feeding areas of the hypothalamus and the cortex. The olfactory system which primarily projects to the limbic system does not play a primary role in adjusting food incentives. Rather, it plays a secondary role in the activation of feeding, as do other external sensory systems. This specialized conditioning mechanism, which specifically adjusts gustatory hedonic values through delayed visceral feedback, is widespread among animals, including man and rat. These two species are remarkably similar in their thresholds and preferences for gustatory stimuli. The behavioral similarities are based on the animals' having similar gustatory systems, similar convergence of gustatory and internal afferents to the nucleus solitarius, and similar midbrain regulatory mechanisms. Thus, it is not surprising that the feeding of obese rats with internal hypothalamic damage resembles the feeding of obese human beings insensitive to the internal signs of this caloric state. Obviously, man has a highly specialized form of symbolic communication and the rat does not, yet man's cognitive specialization does not prevent him from developing aversions to food consumed before illness even when he knows that his illness was not caused by food (43).     

Application of Molecular Marker Assisted Selection in Gene Pyramiding and Selection of New Cultivars

The feasibility of molecule markers' application in gene pyramiding has been proved,and obvious progresses in crop breeding have been made till now.Furthermore,different QTLs or molecular markers linked tightly to yield,quality or resistance may be used for marker assisted selection.MAS will be applied widely in crop breeding due to the development of more gene-based markers and efficient quantitative trait locus(QTL) as well as lower cost marking systems.     

Behavioral dissociation of dishabituation, sensitization, and inhibition in Aplysia

Three forms of nonassociative learning (habituation, dishabituation, and sensitization) have commonly been explained by a dual-process view in which a single decrementing process produces habituation and a single facilitatory process produces both dishabituation and sensitization. A key prediction of this view is that dishabituation and sensitization should always occur together. However, we show that dishabituation and sensitization, as well as an additional process, inhibition, can be behaviorally dissociated in Aplysia by (i) their differential time of onset, (ii) their differential sensitivity to stimulus intensity, and (iii) their differential emergence during development. A simple dual-process view cannot explain these results; rather, a multiprocess view appears necessary to account for nonassociative learning in Aplysia.     

Behavioral sequences during dominance hierarchy formation in chickens

Dominance hierarchies near linearity (containing mostly transitive and few intransitive triads) are common in many species. Analysis of the possible sequences for forming dominance relationships shows that two ensure transitivity, and two others produce either transitive or intransitive triads. Experiments with chickens show that in groups of three and four they most often use the two sequences that ensure transitivity and thus linear hierarchies. Examination of such sequences may help explain the formation of near linear hierarchies in other species.     

Study on Relationship Between Halothane Gene and Behavioral Stereotypies in Pregnant Sows

A simple preparation using the ear tissue for PCR amplification was established for diagnosis of genotypes for halothane in 181 sows. 3 halothane heterozygous pigs were detected. The behaviors of the sows that have different genotypes were observed. The heterozygous sows expressed seem more behavioral stereotyples than halothane resistant. But there is no difference in two genotypes. The behaviour directed trough in heterozygous sows is higher than halothane resistant.     

Behavioral method for study of pain in the monkey

A behavioral method is described in which increasing intensities of electric shocks were applied to the gasserian ganglia of alert monkeys. The animals were trained to press a lever to regulate the shock level. "Pain thresholds" were thereby obtained, and these thresholds were modified by varying the shock duration and by administration of morphine.