Temperature Dependency of the Circadian Locomotor Rhythm in the Cricket Gryllus bimaculatus

概要

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The locomotor rhythm in adult male crickets Gryllus bimaculatus was found to be highly dependent on the ambient temperature level. The crickets were nocturnally active at 25℃, but turned to be diurnal at 20℃ only when entrained to light dark (LD) cycles. The change in activity pattern was mainly caused by the change in the nighttime activity level. Since no animal showed a diurnal rhythm at 20℃ in constant lighting conditions, it is suggested that the diurnality is produced by a temperature dependent masking effect of LD. The temperature level affects the freerunning period (τ) and the daily activity level of freerunning rhythms in constant darkness (DD) or light (LL). However, the Q_10 of τ fell near 1.0 by a temperature compensation mechanism. Delay or advance shifts were often induced by temperature step-down or -up, suggesting that the temperature cycle may be a potent zeitgeber to entrain the locomotor rhythm. The change in temperature sometimes resulted in a splitting of the rhythm into two components. The split components seemed to be driven by the optic lobe pacemakers, since the unilateral removal of the lamina-medulla complex of the optic lobe prevented the splitting.
社団法人日本動物学会の論文
1993-08-16