Secondary circadian clock: Thermal clock of the German cockroach
Date Issued
2008
Date
2008
Author(s)
Huang, Lu-Kun
Abstract
Not only light, but also temperature can synchronize the circadian clock of German cockroach (Blattella germanica). By manipulating environmental conditions, we have proved a unique thermal clock underlying rhythmic locomotion behavior. Thermal and Photoperiodic clock may exert its own influence on the overt rhythm simultaneously, but can also couple forces for a proper phase. For male German cockroach, the locomotor circadian rhythm with only one peak of daily activity was found under constant temperature and LD or DD condition, which was restricted in scotophase or subjective night as a nocturnal animal does. However, a thermal cycle (30:20°C) under constant darkness, might switch the active phase from cold (subjective night) into warm (subjective day) phase, under which caused the presenting of multiple activity peaks. Two of the three peaks were triggered by the thermal clock at the transition of temperature, in the mean time, the photo clock kept a free-running rhythm, and would couple again with the thermal clock when activity peaks were getting closer. Although both clocks share the same opportunity in leading the activity pattern either in synchrony or free-running, the DD condition insinuate the power of photo clock. This finding provides direct evidence of a cooperative multiple-oscillator system for different zeitgebers, and also a novel behavioral basis from current studies on circadian mechanism.
Subjects
non-photic zeitgeber
thermoperiod entrainment
thermophase cryophase
temperature compensation
pacemaker coupling
aftereffect
heterothermic invertebrate
ectothermic insect
Type
thesis
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