ISSN:0022-1945    

DOI:10.1080/09291018309359818

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0022-1945    

DOI:10.1080/09291018309359819

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Circadian leaf movements inOxalisare damped by continuous white light. In contrast, light‐intensity steps initiate and determine phase relations and amplitude of the movement. To test the stimulating influence of different light qualities, the plants were released to continuous white light of 150 lux (or 500 lux, resp.) to provide damping of the rhythm. To this basic white light, LD‐schedules of monochromatic light 12:12 (0,17 mW cm–2: 0) were added. By this method the influence of light‐off and light‐on of monochromatic light could be studied avoiding self‐excitation in the case of physiological darkness. We obtained two results from these experiments:1.Direct induction of the movement and determination of the phase can be attained only by light‐intensity steps with wavelengths below 500 nm. This is valid within 404 nm to 734 nm.2.Although not initiating a direct acceleration of the movement, far‐red (734 nm) enhances the tendency of self‐excitation of the free‐running oscillation. Thus, the damping influence of continuous white light is lowered by far‐red.

ISSN:0022-1945    

DOI:10.1080/09291018309359820

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Although many classical studies of natural ecosystems consider the effect of a variety of environmental variables on data interpretation, that broad, systematic approach has not yet filtered down to more controlled biological studies. Laboratory and field experiments are often designed and analyzed under a restrictively simple definition of the environment. We present a case study of a clinical experiment where the variability observed in the results could be explained only after considering a broader, more complex definition of the environment. As part of a larger experiment examining the effect of60Co radiation on canine cell‐mediated immunity, whole blood lymphocyte stimulation tests were done with blood collected monthly from seven dogs exposed to two different levels of60Co irradiation and from four control dogs, for a period of three years, from 1977 to 1980, under semi‐controlled experimental conditions. Preliminary analysis of these 407 observations showed concurrent fluctuations in immunity in these 11 animals, but the variation could not be explained by either harmonic or pseudoperiodic functions. Application of a seasonal analysis, however, accounted for up to 70% of the observed variability (p < .01). The immune response of dogs at highest60Co dose rates appeared more erratic (p < .001) and less synchronized with the environment than that of dogs exposed to lower doses. An unexpected environmental variable sunspot numbers, was capable of unifying otherwise chaotic data, thus providing a tentative explanation for the immunological response of at least 60% of the dogs studied. The application of contemporary ecological techniques for the formal investigation of the environment, might explain some of the variability associated with so‐called controlled experiments.

ISSN:0022-1945    

DOI:10.1080/09291018309359821

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The present investigation was carried out to determine whether in the pineal gland of male Sprague‐Dawley rats infradian rhythms with respect to serotonin, serotonin‐N‐acetyltransferase (NAT) activity, and hydroxyindole‐O‐methyltransferase (HIOMT) can be detected. The serotonin data obtained over a period of 4 weeks and subjected to power spectral analysis suggest the presence of infradian rhythms in the range of 6 and 4.3 days. NAT activity, obtained over a period of 28 days, revealed a 7‐day‐rhythm. A second peak occurring at 2.3 days remained just below the significance limit. HIOMT activity studied over a period of 8 days showed no statistically significant differences between days. It is concluded that in addition to the well established circadian rhythmicity infradian rhythms are present in the rat pineal gland, the possible causes of which are discussed.

ISSN:0022-1945    

DOI:10.1080/09291018309359822

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Adult male badgers were housed in outdoor pens equipped with an infra‐red actographic system, in the Chizé forest (Western France: 46°19'N; 00°24'W). Various parameters characterizing the diurnal general locomotor activity rhythm were measured: duration of the total activity phase and the actual activity outside the burrow in relation to sunset, sunrise or night duration, activity of passage and profile of seasonal variations. Simultaneously the thyroid activity was controlled by bi‐monthly or monthly measurements of plasma thyroxine concentration.

ISSN:0022-1945    

DOI:10.1080/09291018309359823

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

In freely moving rats the diurnal variation in calcium and phosphate excretion was studied before and after surgical parathyroidectomy. Food was available during either the dark or light period. The lights were on from 0800–2000, the dark phase extended from 2000–0800 h. After parathyroidectomy the urinary rhythms were still present. The most significant change was a decrease in the mean excretory rate and amplitude, although some changes in the time of maximum or minimum excretion also occurred. From this study we conclude that parathyroid hormone is not a prerequisite for these urinary rhythms.

ISSN:0022-1945    

DOI:10.1080/09291018309359824

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Because cats with pontile lesions exhibit an abnormal behavior that is under photoperiodic control, and because circadian rhythms are implicated in photoperiodic control mechanisms, an effort was made to detect circadian rhythms in the cat. Cats were isolated from all extraneous stimuli in soundproof chambers for extended periods of time. Photocells were used to monitor activity, eating and drinking in different LD cycles, in constant light at two intensities, and in constant dark. Freerunning circadian rhythms were found in the constant conditions, and entrained nocturnal patterns occurred in most of the LD cycles. The higher intensities of ambient illumination disrupted the freerunning rhythms. The freerunning rhythms were always greater than 24 h, ranging from 24.2 to 25 h. Measurements of food intake of cats living in a large colony room, obtained by weighing the food, revealed that a nocturnal pattern of entrainment was not present in the majority of the cats. Instead, most cats in the colony exhibited a random pattern of eating throughout the light and dark period of the LD cycle. However, the variation among the cats in the colony was considerable, extending from nocturnal to diurnal patterns of eating. A diurnal pattern of human activity was present in the colony and may account for the disruption of a basic nocturnal pattern. The presence of circadian rhythms in the cat leads us to consider the coincidence models for photoperiodic induction as possible explanations of the photoperiodic control of the lesion‐induced abnormal behavior.

ISSN:0022-1945    

DOI:10.1080/09291018309359825

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0022-1945    

DOI:10.1080/09291018309359817

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor