摘要:

The testicular cycle of subtropical Spotted Munia was studied over a period of 11 months in the following schedules: L/D: 0.25/23.75; L/D: 1/23; L/D: 3/21; L/D: 5/19; L/D: 8/16 and near‐complete darkness. All schedules completely abolished annual gonadal regression with the exception of L/D: 8/16 and near‐complete darkness. In the former, gonads regressed but entered the next reproductive cycle 4 months earlier than the normal scheduled time. In the latter also the cycle was completed though it was sharp and short. It was observed that the greater the duration of the dark period the better the gonadal response is. Sensitivity to short photoperiods/long dark periods seems to be characteristic of the low‐latitude birds; what relevance it has to the normal reproductive cycle of munias in nature is not known.

ISSN:0022-1945    

DOI:10.1080/09291017609359509

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The Influence of Short Periods of Lighting with Different Wavelengths on the Orcadian Changes of the Enzymatic Digestive Activities in Palaemon serratus (Crustacea, Natantia)

ISSN:0022-1945    

DOI:10.1080/09291017609359510

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The effect of continuous illumination and a daily light dark cycle on the free feeding weights of pigeons was determined. Small unsystematic fluctuations occurred within each day during continuous illumination while substantial gains occurred immediately before the dark cycle. The daily accentuation in weight gain did not occur when a daily period without food was substituted for the period of darkness.

ISSN:0022-1945    

DOI:10.1080/09291017609359511

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

A study was made on the developmental rhythms ofEphestia kuehnielladuring different photoperiods: constant lighting (L/L), under conditions of 12 hours light per day (L/D) and in constant darkness (D/D). Observations were made every 2 hrs, for 3 successive 24‐hr periods, of the number of wandering larvae emerging from food, the number of pupations and of imaginai moults. Emergence of wandering larvae is rhythmic only under L/D conditions, and in addition this is also affected by the density of the larvae. Rhythm is least apparent with greatest density of the larvae. Pupation inE. kuehniellais a non‐rhythmic process with each of the photoperiods examined, whereas the imaginai moult is characterized by an endogenous (existing under D/D conditions) rhythm. Emergence of imagines is non‐rhythmic under L/L, and also when pupae under L/D fail to receive the final period of darkness. The rhythm of the imaginai moult is possibly controlled by the biological clock, which stops under conditions of constant light.

ISSN:0022-1945    

DOI:10.1080/09291017609359512

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Wheel‐running activity of forty antelope ground squirrels,Ammospermophilus leucurus, was monitored for several months in both an outdoor cage and in the laboratory. The squirrels demonstrated a highly diurnal pattern which persisted in “constant conditions.” After removal from the field the initial free‐running period was close to 24 hrs, but typically lengthened in a nearly linear fashion at least for the first few months. There was no evidence of any difference in this trend for squirrels, in D/D, L/L 100 lx, 250 lx or 1200 lx. Eventually, about 90 percent of the squirrels had periods longer than 24 hrs.

ISSN:0022-1945    

DOI:10.1080/09291017609359513

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The nuclear volume in cells of the subfornical organ ofRana esculentashows a cyclic annual size change. It is pronounced both in the so‐called Gomori‐positive cells and the ependymal covering of the organ. There appears a maximum in April in the epen‐dyma and in May in the Gomori‐positive cells. The amount of neurosecretory material present in the subependymal layer also shows a maximum in April.

ISSN:0022-1945    

DOI:10.1080/09291017609359514

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Alcohols affect the circadian rhythm of random motility of non dividing autotrophicEuglena gracilisin two different ways:1.In the low concentration range (50–200 mM permanently) ETHANOL lengthens the period up to several hours. Simultaneously the cellular respiration is enhanced and gluconeogenesis and cell division is stimulated. The new metabolic state and the longer stationary period are achieved within a transient of 2–3 days.BUTANOL lengthens the circadian period and induces metabolic activities as ethanol but with an additional lag of two days.PROPANOL and METHANOL are not metabolized by cells in our test conditions as well as they do not lengthen the circadian period.From these results and from supplementary experiments with isolated mitochondria from Euglena we conclude that alcohols affect the rhythm via the metabolism most probably due to the activation of a mitochondrial NADH oxidase available to the cytosol NADH and coupled to three sites of phosphorylation.2.Applied in short pulses of high concentrations (30 min 1–1.5 M) ETHANOL decreases the circadian amplitude by injuring the cells to an extent which depends on the circadian phase at which the alcohol has been applied. The phase dependence for the ethanol susceptibility displays a minimum at the physiological evening and a maximum at the physiological morning. Phase and period length of the rhythm are not affected.Our results do not indicate an essential role of membranes in the mechanism of the circadian clock.

ISSN:0022-1945    

DOI:10.1080/09291017609359515

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

ISSN:0022-1945    

DOI:10.1080/09291017609359508

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor