D. S. Saunders

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The fruit fly Drosophila melanogaster displays an ovarian diapause that is regulated by photoperiod. Newly eclosed female flies (Canton-S wild type) exposed to short days (less than 14 hr of light per day) at 12 degrees C (or 10 degrees C) enter a fairly shallow reproductive diapause. Females exposed to long days (16 hr of light per day) at the same low(More)
Females of a wild-type strain of Drosophila melanogaster (Canton-S), and of several clock mutants (period), were able to discriminate between diapause-inducing short days and diapause-averting long days with a well-defined critical daylength. The critical daylengths of a short-period mutant (pers) and a long-period mutant (perL2) were almost identical, both(More)
1. The circadian rhythm of pupal eclosion inSarcophaga argyrostoma was used as a “measure” of the phase of the covert photoperiodic oscillation in an experimental and formal analysis of photoperiodic induction, particularly in terms of entrainment and phase coherence within the multioscillator circadian system. 2. Phase response curves for the eclosion(More)
Two clock-controlled processes, overt circadian rhythmicity and the photoperiodic induction of diapause, are described in the blow fly,Calliphora vicina and the fruit fly,Drosophila melanogaster. Circadian locomotor rhythms of the adult flies reflect endogenous, self-sustained oscillations with a temperature compensated period. The free-running rhythms(More)
References 1. Jackson, F.R., Bargiello,.T.A., Yun, S.H., and Young, M.W. (1986). Product of per locus of Drosophila shares homology with proteoglycans. Nature 320, 185–188. 2. Citri, Y., Colot, H.V., Jacquier, A.C., Yu, Q., Hall, J.C., Baltimore, D., and Rosbash, M. (1987). A family of unusually spliced biologically active transcripts encoded by a(More)
1. Larvae ofSarcophaga argyrostoma raised in continuous darkness (DD) and in ‘square-wave’ temperature cycles or thermoperiods (Hot:Cold4:20 to20:4, whereH=25 °C and C=15 °C) entered pupal diapause at a rate equivalent to that in DD and a constant temperature equal to the arithmetic mean of the cycle. Therefore, unlike many other insects so tested,S.(More)
1. The pupal eclosion rhythm imSarcophaga argyrostoma was compared with the photoperiodic induction of diapause in the same species. The eclosion rhythm is controlled by a circadian system which free-runs in continuous darkness (DD), after exposure to light/dark cycles (LD) or to continuous light (LL), with an endogenous period, τ, close to 24 h. InLD(More)
Females of Drosophila melanogaster held under short-day photoperiods at a moderately low temperature (12 degrees) enter a state of ovarian diapause in which yolk deposition in the oocytes is suspended (D. S. Saunders, V. C. Henrich, and L. I. Gilbert, Proc. Natl. Acad. Sci. USA 86, 3748-3752, 1989). An enzyme-linked immunosorbent assay (ELISA) using(More)
The induction of larval diapause in the blowflies Calliphora vicina and Lucilia sericata was studied in relation to maternal and/or larval exposure to photoperiod. In C. vicina, maternal experience of short daylength was shown to be more important than larval exposure, although diapause was only observed when the larval rearing temperature was below 15(More)