摘要:

Phase shifting of the circadian conidiation rhythmof Neurospora crassaby pulse treatments with different temperatures, which ranged from 10° to 35°, was compared for the wild type and the clock mutant,frq‐7,in liquid culture. Both strains showed similar phase response curves’ for high temperature (35°) but different phase response curves for low temperature (15°). In the wild type strain, pulses with temperatures higher than 25° caused small shifts in phase in the subjective day phase but pulses with temperatures lower than 25° caused large phase‐delay in the same phase. The clock mutant, frq‐7, showed similar responses to temperature pulses in phases other than the late subjective day phase (CT 9 to CT 14), during whichfrq‐7was almost intensitive to pulses with temperatures lower than 25°. This phase (CT 9 to CT 14) coincided with the phase which has previously been proposed to be affected by mutations at thefrqlocus.

ISSN:0022-1945    

DOI:10.1080/09291018709359926

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The molecular mechanisms of short periodicities (from a few seconds to 15 min), such as glycolytic oscillations, are well known. The essential components of periodic systems in lower organisms, having a period of one to a few days, concern the main cellular compartments. Several clock genes have been identified, but the role of the post‐translational processes or gene expression at the translational level in the control of circadian enzyme activities is questioned. In non‐circadian systems the master element of rhythm regulation, a main pathway of intermediary metabolism where the reversible phosphorylation of a regulatory enzyme plays an essential part, has been identified. Ultradian ( 1 to 4 h) endogenous rhythms have been detected in cell suspensions and in embryonic or differentiated tissues or in isolated organs. Many cellular functions (e.g. protein synthesis, respiration, enzyme activities, electric properties) present the same oscillation frequencies, which cannot be related to mitotic cycles. A cellular ultradian periodic mechanism could then control these activities. In most cases the oscillations observed are irregular i.e. the rhythms most probably represent a spectrum of oscillations. The properties of these rhythms (e.g. phase‐response curve) have to be determined. The regulation of ultradian rhythms remains mostly hypothetical. Their period may be different in different specialized cells of a given organ and for the different physiological functions of an organism. The hypothesis of a central ultradian pacemaker which regulates these rhythms does not appear to be relevant. Ultradian rhythms also seem not to be related to the working of the circadian clock.

ISSN:0022-1945    

DOI:10.1080/09291018709359927

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Longitudinal studies for a period of a year were conducted on five variables with eight normal adult male cats. The variables were adrenaline, noradrenaline, glucocorticoid hormones, body weight, and food intake. Body weight and food intake were determined once every two weeks for the period of a year, and the urinary content of adrenaline, noradrenaline and glucocorticoid hormones were determined once a month for the same period. The annual trend was viewed in three ways, by plotting the means, by a “cosinor"‐like coordinate plot, and by a periodic regression technique. The results indicate that the periodic regression technique provided a good representation of the data in all cases, but the cosinor plot had limited applicability. In the special case when the annual sine curve accounted for all the trend, the cosinor and periodic regression technique are equivalent. Limitations of the cosinor representation involve the non‐sinusoidal shape of the data and the ubiquity of bimodal patterns, a ubiquity existing for both circadian and circannual periods. The temporal organization of the cat involves an annual phase map, and the associated physiological mechanisms and adaptive significance are suggested as important questions.

ISSN:0022-1945    

DOI:10.1080/09291018709359928

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A Circadian rhythm in mammary gland response was observed in steroid primed Sprague‐Dawley rats which received daily injections of ovine prolactin for 5 days at either 0600, 1200, 1800, or 2400. Mammary gland weight (± SE) depended upon the time of day of prolactin injection; 5.97 ± 0.54 g (0600), 2.64 ± 0.46 g (1200), 2.75 ± 0.33 g (1800), 3.38 ± 0.36 g (2400). Consinor analysis of the response to prolactin data showed a highly significant 24‐h rhythm (P < 0.0001) with a mesor of 3.71 ± 0.24 g, an amplitude of 1.65 ± 0.66 g, and an acrophase of _77.95 ± 11.74 degrees (0512 ± 47 min.). The 105 female rats were ovariectomized at age 12 weeks and maintained in a room (22° C) on a 12‐h daily photoperiod (0600 to 1800). Steroid priming was produced by giving injections (i.p.) of2μg of 17 ß‐estradiol‐3‐benzoate and 6 mg of progesterone in 0.1 ml of corn oil for 20 days (0800 ‐ 0900), beginning 2 February). Prolactin (2 mg, 50 IU, in 0.25 ml of 0.9% saline) was injected (i.p.) at either 0600, 1200, 1800, or 2400 for 5 days (beginning 22 February) in the 4 groups of 12 rats. Saline injected and non‐injected groups were also included. The animals were killed 24 h after their last injection or at scheduled times for the non‐injected controls. The freshly dissected mammary glands were weighed.

ISSN:0022-1945    

DOI:10.1080/09291018709359929

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Samples of epidermis, and in some cases tongue epithelium, were taken from tritiated thymidine labelled mice at three hourly intervals throughout the day, daily intervals for a period of two weeks and weekly intervals for a period of 15 months. Samples were counted for total radioactivity in a liquid scintilation counter while other samples were prepared for autoradiography and the determination of the labelling index (LI) (number of cells replicating their DNA). Clear daily (circadian rhythms) were evident. There was no sign of any rhythm within the period of a week or within a month. The radioactivity levels in fresh and fixed skin showed a 16 week periodicity which was clear from a Fourier transform of the data. There was considerable scatter amongst the data and the LI data for epidermis and radioactivity measurements for tongue epithelium both showed a dramatic change in the Spring after which the average values were elevated and more scatter was apparent. It is not clear whether this is a reproducible seasonal effect.

ISSN:0022-1945    

DOI:10.1080/09291018709359930

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The adrenal medulla of male blossomheaded parakeets undergoes seasonal cycles in hormonal concentrations and in the relative number of epinephnne (E) and norepinephrine (NE) cells. NE, but not E, concentrations and cells become significantly (P < 0.001) higher in March than in September and October respectively.

ISSN:0022-1945    

DOI:10.1080/09291018709359931

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Standard polygraphic recordings of sleep and wakefulness were carried out in the captive rook,Corvus frugilegus,in five different periods of the year under natural lighting conditions and outside air temperature. The changes in the daily amount of slow wave sleep well reflected the seasonal changes in daylength. The daily amount of paradoxical sleep was strongly affected by ambient temperature. In all the seasons studied slow wave sleep showed an increase in the course of the night. That increasing trend underwent residual seasonal changes. Paradoxical sleep decreased throughout the night, but in low ambient temperature this trend disappeared.

ISSN:0022-1945    

DOI:10.1080/09291018709359932

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

To determine what environmental factor is the Zeitgeber for the annual change in mass, California ground squirrels(Spermophilus beecheyi)were exposed to several regimes of temperature and length of day. The squirrels were captured when age 4–5 months, kept individually in cages with excess food and nesting material. The temperature was varied with a 6‐month phase shift (SH). The length of day was the same as Santa Barbara (SB) or 6‐month phase shift (SH). The light was provided by cool white bulbs at 10–600 lux.

ISSN:0022-1945    

DOI:10.1080/09291018709359933

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

ISSN:0022-1945    

DOI:10.1080/09291018709359925

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor