摘要:

The role of light intensity in the entrainment (synchronisation) and the shortest entrainable period of the circadian conidiation rhythm ofNeurospora crassawere tested by growing the fungus on solid media under different light‐dark‐regimes. The mutant strainsbd, csp‐1‐bdandfrq‐1‐bdcould be entrained (synchronized) to a period of 12 h. The light phase of this period was inversely correlated with the log of the light intensity. Enhancing the irradiation to 3.65 W/m2white light, the mutantcsp‐l‐bdcould be entrained by as short a period as 2: 2 h. An alteration in the effective wave lengths could not be observed. These results question a total identity between this rhythm and the biological clock found in other eucaryotic organisms.

ISSN:0022-1945    

DOI:10.1080/09291019209360123

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Circannual variations of pineal‐paraphyseal activity of the adult male soft‐shelled turtle(Lissemys punctata punctataBonnoterre) were studied once a month (around the 15th) throughout one year. It appeared that pinealocy te nuclear diameter was minimal in May compared to the other months of this year. The serotonin, norepinephrine and epinephrine levels increased to a great extent in the period April‐June. These findings suggest that there is a distinct circannual variation in pineal gland activity in turtles.

ISSN:0022-1945    

DOI:10.1080/09291019209360124

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Perching activity was recorded in house sparrows(Passer domesticus)exposed to natural light for one year. As expected, the sparrows’ activity duration shortened to 9.6 hours in December when the days were 9.35 hours long; and the sparrows’ activity duration lengthened to 15 hours in June when the days were 15.02 hours long. In addition to this large and expected change, however, there were small changes in activity onsets, ends, and durations which depended on whether the days were lengthening or shortening. Activity onsets anticipated sunrise by 0.2 hours more when days were lengthening. The ends of activity anticipated sunset 0.2 hours more when the days were shortening. The duration of activity time (a) was 0.2 hours longer than photoperiod when the days were lengthening, but it was 0.3 hours shorter than photoperiod when the days were shortening. We made other observations: Some birds displayed a bimodal activity distribution; the duration of the heavy morning bout of activity was a function of photoperiod. Birds with early onsets tended to end their activity late. Phase of the moon and cloudiness had no effect on differences between the activity onsets and ends and the times of sunrise and sunset.

ISSN:0022-1945    

DOI:10.1080/09291019209360125

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

During the reproductive development of male Japanese quail the duration of daily activity is prolonged and the onset of the rhythm of activity is advanced relative to the light‐dark cycle. The neuroendocrine basis for these changes was investigated with focusing on plasma levels of melatonin and testosterone. By means of 4 additional hours of photic stimulation of the brain, after the environmental lights (8L: 16D, lights on at 1000 hr) were turned off, the increase in levels of melatonin after lights‐off was suppressed for a few days. Thereafter the early onset of daily locomotor activity was observed and the gonads began to develop. Similar behavioral changes occurred in castrated quail following direct brain‐illumination or testosterone implants. The testosterone implants also suppressed the increases in levels of melatonin after lights‐off, for a few days. Treatment with an antiserum raised against melatonin (anti‐M) for the first 3 days, to suppress the increases in levels of melatonin after lights‐off, elicited such an anticipatory behavior. These results suggest that suppression of the nocturnal rise in melatonin levels is important for the first steps toward reproductive activity in male Japanese quail.

ISSN:0022-1945    

DOI:10.1080/09291019209360126

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Dark motility was investigated in stationary cultures ofEuglena gracilisKlebs, strain Z. After several days of exposure to darkness, ultradian rhythms of different period length emerged, which could be followed for many cycles. In particular, rhythms of ca. 8 minutes, ca. 1 hour and ca. 1.5 hours were prominent. The ca.‐8‐minute and the ca.‐l.5‐hour rhythms occurred sometimes simultaneously, and also as a modulation of the circadian periodicity.

ISSN:0022-1945    

DOI:10.1080/09291019209360127

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Reptiles possess highly developed behavioural thermoregulatory mechanisms. In tortoises (Agrionemys horsfieldi GRAY) daily rhythms of locomotor activity and preferred temperature were studied under an artificial 12h/12h light‐dark‐cycle in a thermal gradient from 20 to 40°C and under constant ambient temperature. All animals developed a clear daily rhythm of locomotor activity over the whole year. In contrast a daily rhythm of preferred temperature was only found in summer time. These results are discussed under evolutionary aspects.

ISSN:0022-1945    

DOI:10.1080/09291019209360128

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

There are circadian rhythms for urinary excretion of Na* and K+in hypertensive patients. In the present study, the changes in the urinary electrolyte excretion pattern and in daily excretion as a function of the time of drug administration have been investigated after separate administration of 3 diuretics at 8 A.M., 2 P.M. and 8 P.M. A dissociation between the natriuretic and kaliuretic effects was observed. Natriuresis was maximum when hydrochlorothiazide and furosemide were administered in the morning, while the potassium sparing effect of spironolactone was greater following its administration in the afternoon. These results can be explained from the time course of the circadian rhythms in renal Na+and K+excretion.

ISSN:0022-1945    

DOI:10.1080/09291019209360129

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Histological studies of the seasonal testicular cycle in white‐throated munia,Lonchura malabarica(Passeriformes : Ploceidae) Tevealed that this bird breeds from September to January in India. The gametogenesis in the male gonad starts in May when the day length is maximum and the temperature high. The initiation of sexual cycle starts in May‐July. Active spermatogenesis occurs in September to October. The Leydig cell nucleus diameter increases in August just before the onset of spermatogenesis. The diameter of pinealocyte nucleus increases in non‐breeding stage of the bird and decreases during breeding period.

ISSN:0022-1945    

DOI:10.1080/09291019209360130

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0022-1945    

DOI:10.1080/09291019209360122

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor