摘要:

In testing for conspecific activity as a possible Zeitgeber, one must often move the animal into a new environment (new cage) or part of its environment must be modified to allow for social contacts. The aim of this work was to determine whether modifications in the visual structural environment alone can influence the periodicity of the activity rhythm of Red‐winged Blackbirds(Agelaius phoeniceus).Six individually caged adult male birds were examined. Their free‐running period was measured under constant conditions in two different environments. Results clearly show that the periodicity remains stable as long as a bird is kept in the same environment, while it is shifted whenever the bird is transfered into an environment which presents a visually different structure. This source of variation should thus be considered more thoroughly in the interpretation of circadian rhythm experiments conducted under constant conditions of light and temperature.

ISSN:0022-1945    

DOI:10.1080/09291018909360012

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Synchronous cultures of the unicellular algaChlamydomonas reinhardiiestablished by repetitive light and dark cycles displayed both ultradian and circadian rhythms in chlorophyll a levels. The ultradian oscillation had a period of approximately 55 min and appeared superimposed upon the circadian rhythm. These data support the theory that the ultradian oscillator may be a common element in both circadian and cell cycle timing.

ISSN:0022-1945    

DOI:10.1080/09291018909360013

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Data were obtained from the literature on the annual pattern of manic‐depressive attacks and on the time of admission to psychiatric hospitals. These data were correlated with the contemporaneous geomagnetic activity, using the Spearman rank correlation coefficient. The magnetic indices Ap, aa and Na were used, indices which are sensitive to solar corpuscular radiation. Manic‐depressive attacks and geomagnetic disturbances exhibited prominent seminannual patterns, with the correlations positive and statistically significant in half the tests. No significant outcomes were obtained with the admission data. The literature on geomagnetic effects on melatonin and on a melatonin dysfunction in depression is briefly reviewed, and a possible geomagnetic factor in depression is hypothesized.

ISSN:0022-1945    

DOI:10.1080/09291018909360014

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The dynamics of bile secretion was studied on 53 cannulated male Wistar rats in normal conditions and during intravenous infusions of gastrointestinal hormones. Both secretin and CCK (Boots) induced the greatest choleretic response. Bile diversion caused a significant fall in bile flow rates as compared with rats receiving constant intraduodenal infusion of Na‐taurocholate. In all the groups clear 1.5–2 hr oscillations, lasting much longer than the interdigestive motility cycles in this species, were observed. The significance of these oscillations was confirmed by the Fisher's test and the normalized periodogram values computed for the frequency band 0.2–0.33 (1.5–2.5 hr) period were significant in all the experimental groups. However, the significance of the frequency band decreased along with the increasing stimulation potency of the hormones. Thus, neither changes in bile acid secretion nor alternations in main gastrointestinal hormone levels seem to be responsible for the occurrence of the ultradian rhythm of bile flow in the rat.

ISSN:0022-1945    

DOI:10.1080/09291018909360015

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Electrographic sleep and brain temperature (Tb) were monitored in captive rooks,Corvus frugilegus,for several consecutive 24‐h periods under natural entrained conditions in two different seasons. The courses of brain temperature after the transitions between vigilance states including slow wave sleep (SWS), paradoxical sleep (PS) and wakefulness (W) were calculated. A consistent decline in Tb occurred when birds fall into SWS. During transition from SWS into W a significant rise in Tb was observed. Changes in Tb associated with PS could not be ascertained. The experiments showed the existence of close connections of SWS and W with short term fluctuations superimposed on the daily course of Tb.

ISSN:0022-1945    

DOI:10.1080/09291018909360016

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In young male domestic fowls, the effects of weekly 8‐h advance or delay shifts on growth and circadian rhythm of the core temperature were evaluated. The results indicate that the growth rate was significantly higher only in the birds of the advance schedule. ANOVA results suggest statistically significant inhibition in the growth rate of delay‐schedule birds. Further, the birds of the control group exhibited a circadian rhythm in core temperature. This rhythm disappeared in delay‐schedule birds soon after imposition of the shifts and reappeared on the 3rd post‐shift day. This phenomenon was found to be uncommon among the advance‐schedule birds. The poor growth rate of the delay‐schedule birds could be attributed to desynchronization of core temperature circadian rhythm.

ISSN:0022-1945    

DOI:10.1080/09291018909360017

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

We investigated the influence of the pituitary gland on the circadian organization of the urinary rhythms of sodium, potassium, phosphate and water. Control and hypophysectomized (HPX) rats were studied during a light‐dark (LD) (12h:12h) cycle, constant illumination (LL) and constant darkness (DD). The latter was achieved by bilateral ocular enucleation. In addition to anterior pituitary insufficiency some rats exhibited partial diabetes insipidus (HPX‐DI) and some did not (HPX‐NDI). During DD the mean period was 24.5 hrs for control rats and HPX‐NDI rats. In contrast to blind rats animals maintained under LL conditions showed a decrease in period after 8 days, i.e. from about 25.3 hrs to about 24.4 hrs in all groups. Generally, no significant differences in period were found between HPX‐DI, HPX‐NDI and control rats. Under LD conditions the acrophases for sodium, potassium and water excretion shifted, occuring about 6 hrs later in HPX‐NDI rats and about 9 hrs later in HPX‐DI rats compared to control animals. In contrast, the acrophases for phosphate remained unchanged for HPX rats. Normal phase angles were restored by corticosterone and thyroxine substitution. This study demonstrates that the pituitary gland is not essential for the generation of urinary excretory rhythms; however, this organ plays a critical role in the phase setting of some renal excretory rhythms.

ISSN:0022-1945    

DOI:10.1080/09291018909360018

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The entrained rhythm in food approaches, representative of the circadian fluctuation in locomotor and food intake activity was recorded from 12 rabbits eatingad libitumduring exposure to an LD 12:12 h‐regimen. They were also subjected to 53 h‐sessions with the same LD alternation, in which blood samples were taken at 2 h‐intervals. During these sessions 6 of them were permitted to eat freely whereas the others were food‐deprived. It appeared that in eating rabbits plasma levels are higher for glucose and a‐amino nitrogen but lower for free fatty acids and, further, that eating specimens exhibit marked circadian fluctuations in the levels of glucose and FFA which are closely correlated with, and probably a consequence of, the circadian rhythm in the amounts of food actually taken up in the course of the sessions. In fasting rabbits, however, the same plasma parameters show rhythms with quite another time course, that can be attributed to the circadian fluctuations in (locomotor) activity and endocrine balance.

ISSN:0022-1945    

DOI:10.1080/09291018909360019

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0022-1945    

DOI:10.1080/09291018909360011

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor