Temperature pulses synchronise the crayfish locomotor activity rhythm

Abstract

Unrestrained crayfish maintained in the dark exhibit a unimodal circadian activity that freely runs with a period of approximately 24 h rhythm that is able to entrain light-dark cycles. Although the activity rhythm has been shown to compensate for temperature, its potential for temperature synchronisation is unknown. In this work, we analysed the effects of cold-water pulses on crayfish locomotor activity. The crayfish were maintained under a 12:12 light-dark (LD) cycle and 30-min cold (58C) water pulses were applied at three different circadian times (CTs). The crayfish were subsequently kept in darkness. Cold-water pulses applied at the beginning of the subjective night produced phase advances whereas pulses applied at the end of the subjective night produced phase delays. The magnitudes of the phase shifts were similar to those produced by light pulses but the direction was a mirror image. These findings suggest that the temperatureand light-synchronising pathways differ in crayfish.

Circadian and ultradian oscillations in bilateral rhythms of the crayfish chelipeds

“…In periodograms of the locomotor rhythm of the crayfish P. clarkii , the effect of monochromatic light pulses, retinal ablation, and changes in illumination and temperature on circadian oscillations have been associated with the primary peak ( Miranda-Anaya and Fanjul-Moles, 1997 ; 13). However, the effect of these stimuli on the additional peaks ( Miranda-Anaya and Fanjul-Moles, 1997 ; Palma-Anzures et al, 2012 ) can also be observed, which can be linked to ultradian oscillations.…”

“…On the other hand, these results could be in line with those of other previous studies. In locomotor rhythm periodograms of the crayfish P. clarkii , associated with the effect of monochromatic light pulses, retinal ablation, and changes on illumination and temperature on the primary peaks ( Miranda-Anaya and Fanjul-Moles, 1997 ; Palma-Anzures et al, 2012 ), effects on additional peaks can also be observed. If the primary peak of the periodograms were related to circadian oscillations and the additional peaks to ultradian oscillations, the effect of these zeitgebers and retinal ablation on ultradian oscillations could be observed.…”