摘要:

Slow spontaneous oscillations of the catalytic capacity of enzymes in solution under constant conditions were shown in extracts containing malate dehydrogenase and phosphoenolpyruvate carboxylase from the leaves ofKalanchoe blossfeldiana. Statistical treatment of the data with a fitting model indicates periods ranging from 16 h to 27 h depending on the experiments.

ISSN:0022-1945    

DOI:10.1080/09291018509359865

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

InTetrahymena thermophila, the ultradian rhythm of tyrosine aminotransferase activity was investigated under free‐running conditions. The rhythm persisted in the presence of 1 mM emetine, although the drug efficiently inhibited both protein synthesis and cell division. Also 250 mM hydroxyurea, which suppressed cell growth to a high degree, did not prevent the rhythm. These data support the concept of an ultradian oscillator working independently of translation and beingnota consequence of the “cell cycle”;, although under normal physiological conditions the rhythm of tyrosine aminotransferase is accompanied by and equiperiodic with the rhythm of cell division, both in the ultradian and circadian growth modes.

ISSN:0022-1945    

DOI:10.1080/09291018509359866

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

InTetrahymena thermophila, the ultradian rhythm of tyrosine aminotransferase activity was investigated at 3 different constant temperatures (10, 20, 30°C), after the cells had been previously synchronized by temperature cycles of 4 h 20°C/1 h 0°C. In these conditions, the free‐running period of the enzyme rhythm proved to be temperature compensated. By contrast with this steady state behaviour, temperature jumps of 20?10°C or 20?30°C, if applied in an appropriate phase, resulted in marked phase shifts. Hence, the ultradian rhythm investigated shares the temperature behaviour of circadian rhythms, i.e., to be temperature compensated in the steady state, and to be reset by temperature jumps.

ISSN:0022-1945    

DOI:10.1080/09291018509359867

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

New features incorporated into the BMDP‐program package since 1981 allowed to greatly simplify the evaluation of the desired quantities and their errors. For the mesor the exact expression is used in the new program.

ISSN:0022-1945    

DOI:10.1080/09291018509359868

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A lighting control system interfaced with the inexpensive VIC‐20 microcomputer is described which can automatically vary light intensity and photoperiod in the laboratory to simulate natural intensity curves throughout the day, and daylengths throughout the changing seasons. Adjustments to compensate for differing latitudes and habitat types are easily accomplished through modifications of the controlling software. The system enables the study of effects of crepuscular lighting and circannual periodicities of physiology and behavior which were previously infeasible. Circuit diagrams, details of construction for simultaneous control of three sets of lights, and a menu‐driven BASIC program for accurately simulating the annual light cycle for any point between the equator and 60 degrees north latitude are presented. The importance of photoenvironment in laboratory studies of physiology and behavior is discussed.

ISSN:0022-1945    

DOI:10.1080/09291018509359869

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Cold footbathes and those with alterated temperature (warm/cold) in a curative dosage, which is used in physical treatment or spa medicine, cause elevations of the oropharyngeal mucosa temperature. The extent of this reaction underlays circadian variations. The local resistance of the oropharyngeal mucosa against infections is better after elevation of the temperature.

ISSN:0022-1945    

DOI:10.1080/09291018509359870

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The body temperature of the domestic cat was determined by radiotelemetry from implants in the peritoneal cavity. Longitudinal data were collected and analyzed with a periodic regression technique. Thermograms and actograms were constructed in order to study the transients that follow a phase shift of the LD cycle and to discern the freerun in body temperature and activity in constant dark. The main results indicate that the domestic cat has a prominent circadian rhythm in body temperature. Prominent transients occur after a phase shift of the LD cycle, and the temperature rhythm freeruns in constant dark, maintaining a constant phase angle relationship with the freerunning rhythm in activity.

ISSN:0022-1945    

DOI:10.1080/09291018509359871

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Rats with a 4‐day estrous cycle were given a single dose of reserpine (62.5, 125, 500, 1000 or 2000 μg/kg body wt) or chlorpromazine (1, 2.5 or 5 mg/kg body wt) at 13.00 h on the days of estrus, diestrus 1, diestrus 2 or proestrus and were autopsied on the next expected day of estrus. The doses of reserpine (in μg/kg body wt) necessary to block ovulation during the cycle were 500 at estrus, 62.5 at diestrus 1, 500 at diestrus 2 and 2000 at proestrus, and for chlorpromazine (in μg/kg body wt) 2.5 on diestrus 1 and diestrus 2 and 1 in proestrus. On estrus, at 13.00 h, chlorpromazine was ineffective to block ovulation.

ISSN:0022-1945    

DOI:10.1080/09291018509359872

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Under DD, the compound eyes of the adult cricket,Gryllus bimaculatus, showed the circadian electroretinographic (ERG) rhythm peaking in the subjective night. The rhythm clearly persisted even after optic tract severance. When the optic tract was cut unilaterally, a 24‐hr LD given to the eye of the operated side entrained the ipsilateral eye, but did not entrain the contralateral intact eye kept in DD. Consequently, the ERG rhythms of the two eyes were desynchronized. These results indicate that the ‘optic lobe‐compound eye’ system (OCS) contains the complete circadian system housing photoreceptor, pacemaker and effector for the ERG rhythm.

ISSN:0022-1945    

DOI:10.1080/09291018509359873

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The common view that circadian rhythms evolved as an adaptation to the exogenous daily cycle is questioned regarding early eukaryotic unicellulars. An alternative explanation of their origin is presented: circadian ‐ and other endogenous ‐ rhythms made available a temporal coordination mechanism to those intracellular symbioses which developed into eukaryotic cells. For the functioning of such associations a synchronization between host cells and endosymbionts has to be considered essential. It may have been achieved by the coupling of cellular activities to endogenous rhythms.

ISSN:0022-1945    

DOI:10.1080/09291018509359874

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor