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W Engelmann

Publications and source records attributed to W Engelmann.

29 records · Page 2Linked to original sources
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Temperature sensitive events between photoreceptor and circadian clock?

The phase shifting action of low temperature pulses of 6 degrees C and 2 h duration administered to the various phases of the Drosophila pseudoobscura circadian rhythm and the action of light pulses given 30 min after the beginning of these low temperature pulses have been investigated. The phase response curve obtained from experiments with light pulses during low temperature cannot be explained on the basis of a straightforward and sequential phase shifting of the oscillation by the various transitions in the pulses. The response curve, after the slight phase shifting action of the temperature pulses is corrected for, resembles the standard phase response curve4 for light pulses (at 20 degrees C) in its wave form but not in its time course. Our curve is shifted in time in a manner that indicates that the light pulses accompanying the low temperature pulses arrived at phase points 1.5 h later than the actual phases at which they were given. We attribute this delay to a slowing down of the information that is apparently transmitted by a process that is temperature dependent.

Animals↗
PubMedDate not supplied

Free-running human circadian rhythms in Svalbard.

The body temperature, activity-rest time, electrolytes of urine samples and mood was measured in two persons a 19 day period under continuous light conditions in the arctic (vicinity of Ny Alesund, Svalbard-Spitsbergen). For temperature recording a new thermoprobe and a portable printer was used. Possible week Zeitgeber of the 24 hour day did not synchronize the circadian system, since circadian rhythms of about 26 hours were found. These results open up the possibility to study effects of drugs on the circadian system of humans under Svalbard conditions.

Adult↗
PubMedDate not supplied

Influence of lithium ions on human circadian rhythms.

Lithium carbonate lengthens the circadian period of body temperature and sleep-wakefulness in humans under temporal isolation (arctic conditions in Svalbard, 79 degrees N) in two out of four groups.

Adult↗
PubMedDate not supplied

Evidences for circadian rhythmicity in the per0 mutant of Drosophila melanogaster.

per0 Mutants of Drosophila melanogaster which are exposed to light-dark cycles (LD) with different Zeitgeber period (T) have a limited range of entrainment. Entrained flies show a characteristic phase relationship of activity to the LD which depends on the period of the driving cycle as expected by oscillator theory. Both facts are taken as evidence that per. possesses endogenous oscillators and that the per gene product is not concerned with central clock structures but rather might be responsible for the mutual coupling between the individual oscillators in a multioscillatory system controlling locomotor activity.

Animals↗