摘要:

A new and inexpensive electronic device is described which enables serial registrations of the oscillatory contraction activities at closely neighbouring sites within plasmodia of Physarum polycephalum. At the same time, this new construction allows the immediate automatic transformation of the original sinusoidal contraction curves into multiple phase graphs.

ISSN:0022-1945    

DOI:10.1080/09291018409359857

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The radial contraction‐relaxation activity was recorded in Physarum by the infrared technique either at distant sites or along a linear array of 5 or 10 sites, each 2.5 mm distant from each other. There is a tendency in the plasmodium to maintain the same period throughout the whole plasmodium, although the period may change with time. The recording at a single site represents aggregated rhythms, the mode of which is either synchronous, or twinned or of the shoulder type. The last two modes refer to a split rhythm. There is also a tendency toward synchrony at neighbouring sites. However, there is often a gradient of phase along the array of recorded sites. The gradient is pot stable and often shows a reversion. This reversion displays the type 0 resetting; the resetting occurs spontaneously. Usually the resetting takes place only in a part of the oscillating system at a certain site. The local synchronous mode may thus be changed into the twinned or the shoulder mode.

ISSN:0022-1945    

DOI:10.1080/09291018409359858

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Control by photoperiodism of glycolysis and the connected “Crassulacean Acid Metabolism”; pathway in the leaves ofKalanchoe blossfeldianais shown to achieve strict coordination between the two pathways, and more particularly between their key‐enrymes (phosphofructokinase and phosphoenolpyruvate carboxylase) with respect both to seasonal and day‐night variations. After transfer from long days to short days, increases in the catalytic capacity of the enzymes and the size of metabolite pools follow similar kinetics. These changes are accompanied by coherent phaseshiits in the day‐night rhythms of metabolite concentration and of enzyme capacity. The results suggest that rapid readjustments of functions seem to be involved in the entrainment of enzyme rhythms by lights‐off.

ISSN:0022-1945    

DOI:10.1080/09291018409359859

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Mitotic rhythms were investigated in the chick corneal epithelium under various lighting regimens. Day‐old chicks were subjected to LD 14:10 (14 hr‐light: 10 hr‐darkness) for 2 weeks and the number of mitotic cells were counted in the central and peripheral regions of the cornea. The mitotic activity was high in darkness and low in light, and higher activity in the central region than in the peripheral region was observed. Anticipatory sharp rise in mitotic activity was observed just after light off. When chicks were reared in LD 12:12 (light on 06:00–18:00) and in inverted LD 12:12 (light on 18:00–06:00), the phase of the rhythm in normal LD 12:12 was different by 180° from that in inverted LD 12:12. When chicks were transferred to continuous light or continuous darkness after 2 weeks in LD 14:10, the mitotic rhythm disappeared in continuous light, but it continued in continuous darkness, suggesting a circadian nature of the rhythm. Two‐day old chicks, which were given only one LD cycle, also showed a distinct mitotic rhythm. Chicks kept in continuous light for 13 days could not recover the mitotic rhythm when they were transferred to continuous darkness.

ISSN:0022-1945    

DOI:10.1080/09291018409359860

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

LiCl (195μg/g body weight and day) reduces water uptake in Syrian hamsters by 40%. Sleep duration is increased from 50% per day to 60% per day. Other behavioural items are hardly influenced. Shortening and lengthening of the circadian period was induced by Li+in individual hamsters, but the mean period of the population was not changed. The upper limit of entrainment is increased by Li+.

ISSN:0022-1945    

DOI:10.1080/09291018409359861

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Social stimulation is not usually considered to be a circadian synchronizer of activity in insects. We investigated whether it could have any effect on synchronization and resetting capacity in insects with cauterized eyes. Direct continuous observations were carried out in groups ofPeriplaneta americanacomposed of two operated animals and eight controls. When night fell at the same time as before surgery, sexual and locomotor activity of operated animals remained synchronized with the activity of control animals. But when nightfall was postponed by 6 h, operated animals were unable to lengthen the activity peak, as long as the activity threshold stayed at its minimum level. Social stimulation resulted in modifications of and interactions with the temporal activity distribution within the threshold limits, but was unable to reset the circadian clock; so it may be questioned whether it should be regarded as a circadian synchronizer in a strict sense. Circadian rhythm of food intake disappeared in operated animals; this unstable character which has already been mentioned by other authors, even in intact animals, is discussed.

ISSN:0022-1945    

DOI:10.1080/09291018409359862

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Studies with active normothermic thirteen‐line ground squirrels,Spermophilus tridecimlineatus, demonstrated an annual cycle in the core‐skin temperature gradient which persisted in thermoneutral ambient temperature conditions (30°C). The thermal gradient was at a maximum during the October through January interval and at a minimum for the February‐March interval. This pattern suggests that the fat stores of the animal affect its heat conservation capabilities and possibly the manner of temperature regulation.

ISSN:0022-1945    

DOI:10.1080/09291018409359863

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0022-1945    

DOI:10.1080/09291018409359856

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor