Geckos: adaptive significance and energetics of tail autotomy

Coleonyx variegatus is adapted to readily sacrifice its tail to predators. This adaptation is associated with characteristic tail behavior and rapid tail regeneration. There is no facultative metabolic increase associated with tail regeneration, and energy normally allocated to body growth and maintenance is diverted to tail regeneration. This supports the contention that tail behavior, autotomy, and rapid regeneration evolved as mechanisms promoting survival in terms of predator escape.     

Bird energetics: effects of artificial radiation

Radiant energy reduces oxygen consumption in birds; this reduction is correlated with feather color, being greater in dark birds (26 percent reduction) than in white ones (6 percent reduction). With radiant energy (basking), the cow-bird effectively increased its insulation, thus shifting the lower end of the zone of thermal neutrality down by as much as 10 degrees C (35 degrees to 25 degrees C).     

Theoretical studies of the energetics and dynamics of chemical reactions

Computational studies of basic chemical processes not only provide numbers for comparison with experiment or for use in modeling complex chemical phenomena such as combustion, but also provide insight into the fundamental factors that govern molecular structure and change which cannot be obtained from experiment alone. We summarize the results of three case studies, on HCO, OH + H(2), and O + C(2)H(2), which illustrate the range of problems that can be addressed by using modern theoretical techniques. In all cases, the potential energy surfaces were characterized by using ab initio electronic structure methods. Collisions between molecules leading to reaction or energy transer were described with quantum dynamical methods (HCO), classical trajectory techniques (HCO and OH + H(2)), and statistical methods (HCO, OH + H(2), and O + C(2)H(2)). We can anticipate dramatic increases in the scope of this work as new generations of computers are introduced and as new chemistry software is developed to exploit these computers.     

Condensed-matter energetics from diatomic molecular spectra

Analyses of molecular spectra and compression data from crystals show that a single function successfully describes the dependence on interatomic separation of both the potential energy of diatomic molecules and the cohesive binding energy of condensed matter. The empirical finding that one function describes interatomic energies for such diverse forms of matter and over a wide range of conditions can be used to extend condensed-matter equations of state but warrants further theoretical study.     

Circadian timing of cancer chemotherapy

Animal studies have indicated that the time of administration of adriamycin and cisplatin, two widely used anticancer drugs, has a profound effect on their toxicity. This effect in cancer chemotherapy was studied in 31 patients with advanced ovarian cancer. Patients received at least eight monthly courses of adriamycin that were followed 12 hours later by cisplatin, with adriamycin randomly administered at either 6 a.m. or 6 p.m. The results show that in the group receiving adriamycin in the evening and cisplatin in the morning (i) twice as many patients required reductions in dosage and delays in treatment, (ii) four times as many treatments had to be delayed, (iii) drug dosages had to be modified downward three times as often, and (iv) even with more dose attenuation and treatment delays, treatment complications were still about two times more common as in the group receiving adriamycin in the morning and cisplatin in the evening. These findings show that the circadian stage at which anticancer drugs are given to patients should be carefully considered.     

Circadian rhythm of brain self-stimulation behavior

Under constant conditions of light, sound, temperature, and humidity, rats exhibited circadian rhythmicity in rate of bar-pressing with hypothalamic and septal reinforcing brain stimulation. Variations in reinforcer magnitude aflected absolute levels of operant response emission but not the frequency of the circadian rhythm. In long sessions, the time of peak responding deviated systematically from a strict 24-hour period. Such data show marked similarity to free-running rhythms of motor activity.     

Circadian clock in insect photoperiodism

Night-interrluption experiments with the wasp Nasonia vitripennis maintained in 48- and 72-hour light: dark cycles reveal two and three peaks of light sensitivity (diapause inhibition), respectively. The first peak is 19 hours after lights-on in all regimes tested; the later peaks occlur at 24-hour intervals thereafter, providing evidence for the circadian nature of the photoperiodic clock in this insect.     

Lightning on jupiter: rate, energetics, and effects

Voyager data on the optical and radio-frequency detection of lightning discharges in the atmosphere of Jupiter suggest a stroke rate significantly lower than on the earth. The efficiency of conversion of atmospheric convective energy flux into lightning is almost certainly less than on the earth, probably near 10(-7) rather than the terrestrial value of 10(-4). At this level the rate of production of complex organic molecules by lightning and by thunder shock waves is negligible compared to the rates of known photochemical processes for forming colored inorganic solids.     

鳞翅目昆虫生物钟的研究进展与展望

经过长期的自然演化,昆虫生命活动和行为中有着明显的昼夜和季节的节律性周期变化——生物钟(circadian clock)。鳞翅目昆虫是当前物种最丰富的昆虫群体,包括蝴蝶和飞蛾约16万种,其中近70%的重要农林害虫属于鳞翅目。而鳞翅目昆虫生物钟的研究进展对于深入剖析鳞翅目昆虫丰富多变的生理行为调控机制,有效开展鳞翅目经济昆虫的生产及农林害虫防治具有重要意义。总结了昼夜节律生物钟对鳞翅目昆虫孵化与取食、生长与变态、生殖与滞育、求偶与迁飞等生理行为的影响,重点概述了鳞翅目昆虫生物钟分子调控机制、生物钟与内分泌激素协同调控机制等重要研究进展,并基于生物钟原理探讨了鳞翅目昆虫与植物协同进化关系及重要生态意义,展望了将生物钟理论应用于农业害虫防治和经济昆虫饲养改良的应用前景。     

Circadian clocks in daily and seasonal control of development

The rotation of the earth results in regular changes in the light environment, and organisms have evolved a molecular oscillator that allows them to anticipate these changes. This daily molecular oscillator, known as the circadian clock, regulates a diverse array of physiologies across a wide variety of organisms. This review highlights a few of the insights we have into circadian clock regulation of development, in both plants and animals. A common thread linking plants and animals is the use of the circadian clock to sense changes in day length and to mediate a diverse number of photoperiodic responses.