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Circadian component influences the photoperiodic induction of diapause in a drosophilid fly, Chymomyza costata.

Abstract：

:The last-instar larvae of a drosophilid fly, Chymomyza costata enter diapause in response to the dark-phases longer than 9 h (Yoshida, T., Kimura, M.T., 1995. The photoperiodic clock in Chymomyza costata. Journal of Insect Physiology 41, 217-222). In order to switch the developmental programming of the sensitive larvae from continuous development to diapause, after they were transferred from the short (8 h) to the long (14 h) dark-phase, significantly less time (1-2 days) was required when the dark-phase was abruptly and asymmetrically extended into the evening, than when it was extended symmetrically into both morning and evening (2-3 days), or asymmetrically into the morning hours (4-6 days). Diapause was also induced in 40-70% of sensitive larvae that were reared under the gradually shortening light-phase (from 16 h to 2 h, by 1 h in each cycle), despite that the dark-phase remained constant and short (8 h). Larvae developed continuously, however, when reared under the gradually extending light-phase (from 16 h to 24 h) and a constantly short dark-phase. We interpret such results, with the help of the two-oscillator model of circadian rhythmicity (Pittendrigh, C.S., Daan, S., 1976. A functional analysis of circadian pacemakers in nocturnal rodents. V. Pacemaker structure: A clock for all seasons. Journal of Comparative Physiology A 106, 333-355), as indicating that two mutually coupled oscillators (evening and morning) differing in their entrainability may participate in measuring of the dark-phase duration. The levels of dopamine (DA) and serotonin (5-HT) in the larval CNS transiently increased (by up to 20%) after the dusk, while no apparent change was observed during the dawn. The dusk-related increase was observed also after the asymmetric extension of the dark-phase into evening, while the asymmetric extension into morning had no effect on the levels of the DA and 5-HT.

journal_name

J Insect Physiol

journal_title

Journal of insect physiology

authors

Kost'ál V V,Noguchi H,Shimada K,Hayakawa Y

doi

10.1016/s0022-1910(99)00195-x

keywords:

subject

Has Abstract

pub_date

2000-06-01 00:00:00

pages

887-896

issue

eissn

0022-1910

issn

1879-1611

pii

S002219109900195X

journal_volume

pub_type

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Circadian component influences the photoperiodic induction of diapause in a drosophilid fly, Chymomyza costata.