摘要:

Daily injections of neurotransmitter‐affecting drugs induced spring migratory and reproductive conditions in white‐throated sparrows,Zonotrichia albicollis, during the fall. Injections of DOPA (catecholamine precursor) 12 h after 5‐HTP (serotonin precursor) was most stimulatory for development of spring conditions. Summer and fall conditions followed during subsequent months in a manner similar to the natural sequence. Changes in the temporal relations of circadian neural activities may account for seasonal alterations of metabolism and behavior.

ISSN:0022-1945    

DOI:10.1080/09291018309359802

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Misonidazole, a heterocyclic nitrocompound shown to act as hypoxic cell radiosensitizer, is supposed to inhibit cellular oxygen consumptionin vitro, depending upon certain conditions such as MIS concentration, and cellular content of various substrates. The effect of intraperitoneal injection of MIS at doses of 0.5 mg/g body weight, at 8 different time‐points during the 24‐h cycle, on the oxygen utilization of hepatic cellular homogenates of female Balb/c mice was investigated. A statistically significant rhythmicity was detected by analysis of variance among the O2uptake values of control homogenates, whereas this rhythmicity was altered by treatment with MIS: inhibition of O2consumption appeared when MIS was injected at 18.00 h or at 21.00 h, coinciding in time with the acrophase of the physiological rhythm of control O2uptake.

ISSN:0022-1945    

DOI:10.1080/09291018309359803

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Eight rabbits were synchronized by LD 14:10 (200–250: 0 Lux). After more than 4 weeks of exposure to this Zeitgeber two types of experiment were performed on each specimen. In type I experiments the electroretinograms (ERG's) and Visually Evoked Potentials in response to 3 μsec flashes were recorded during the “day‐time‐potential” phase of the circadian rhythm, at first during steady illumination at either 1200 or 2500 Lux and thereupon in darkness, and also during the “night‐time‐potential” phase, but then firstly in darkness and afterwards during illumination with the same intensity. In type II experiments the responses to the same flashes were, again, recorded in both phases but now the sequence of illumination ‐ at identical level ‐and darkness was reversed. It appeared that programmed changes in photic responses occurred both in darkness (in type I experiments) and during steady illumination (in experiments of the other type) but that the circadian change in amplitude of the ERG b waves was larger for the ERG's recorded in darkness than for those obtained during illumination. It further appeared that the suppressive influence exerted by background illumination on the ERG's is stronger during the N.T.P.‐phase of the rhythm than in the other phase.

ISSN:0022-1945    

DOI:10.1080/09291018309359804

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The experiments were carried out on the house crickets,Acheta domesticusL. reared in LD 12:12 photoperiod at 28°C. The levels of neurosecretion synthesis were studied by means of autoradiography using35S‐cysteine as a precursor for the neurosecretory proteins.

ISSN:0022-1945    

DOI:10.1080/09291018309359805

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Quasi‐entrainment, characterized by a fluctuating latency in the presence of one‐to‐one frequency entrainment, has been elicited in two Bonhoeffer‐Van der Pol type oscillators coupled together on a digital computer via a feedback network that is a function of the average activities of the adjoined units. Such behavior was observed only when specially constructed sigmoidal coupling functions were in place. In contrast, with linear functions in place, the constellation of resulting stable or unstable equilibrium points made the system orbitally stable or unstable depending on initial conditions. Based on the coupling function and system architecture a criterion for predicting ultimate behaviors is developed and tested. Results are contrasted with fluctuating latencies previously observed in loosely coupled heart cell aggregates.

ISSN:0022-1945    

DOI:10.1080/09291018309359806

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The underlying basis of biological clocks has completely eluded scholars to the present. Its nature appears as mysterious today as it did at the turn of the century despite the vast efforts by a great many able scholars. W. Pfeffer felt compelled to conclude in 1915 that each organism contained its own completely independent clock system. The bases were his ability to reset the phase of the clock‐timed daily rhythms at will together with the observation that in constant light and temperature the period of the rhythms usually assumed some arbitrary value ("free‐running") deviating slightly from 24 hours. This conclusion appeared later to be supported by a described light‐dependence of the frequency of the free‐running, the deviations of Q10’s of periods from 1.00, and discovery of genes and chemicals which could alter the free‐running period. The vast majority of investigators have adopted this hypothesis and have sought in vain for internal timers with clock properties.

ISSN:0022-1945    

DOI:10.1080/09291018309359807

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0022-1945    

DOI:10.1080/09291018309359808

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0022-1945    

DOI:10.1080/09291018309359809

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0022-1945    

DOI:10.1080/09291018309359810

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0022-1945    

DOI:10.1080/09291018309359801

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor