Tetsu Saigusa et al. (2002) Japanese Worm Meeting "Circadian behavioral rhythm in C. elegans."

Masatoshi Hagiwara, Naoaki Ishii, Akihiro Tanakadate, Tetsu Saigusa, Yoshishige Kimura, Motohide Yamamoto, Kenji Hasegawa

[Japanese Worm Meeting, 2002]

Transcriptional/translational feedback loops between clock genes such as per and tim (first cloned in Drosophila ) and their protein products are thought to constitute the core of the circadian clock. C. elegans has been known to inherit a per homologue, lin-42 . However, mRNA levels of lin-42 oscillate synchronously with approximately 6-hr molting cycle at the larvae stage but become flat at the adult stage, so that whether the nematode shows any circadian rhythmicity has been mysterious among chronobiologists. Recently we have succeeded to measure a convincing circadian rhythm in the locomotor activity in adult nematodes using the automatic device (Bug-tracker). Our findings suggest possibility that per is not indispensable for the circadian rhythm in the animal kingdom and that further ubiquitous system may exist which governs the circadian fluctuation of even per . To identify the ubiquitous system, we have developed the Bug-tracker to simultaneously measure the behavior rhythms of more nematodes with knockout or rescued gene(s). In the present study, we report the developed device (Nan-Vo) and some results of the behavioral rhythm in nematode mutant.

Tetsu Saigusa et al. (2003) International Worm Meeting "C. elegans as a novel model system for the molecular study of circadian clock."

Tetsu Saigusa, Masatoshi Hagiwara, Kenji Hasegawa, Naoaki Ishii, Yoshishige Kimura, Akihiro Tanakadate

[International Worm Meeting, 2003]

Transcriptional/translational feedback loops between clock genes such as per and tim (first cloned in Drosophila) and their protein products are thought to constitute the core of the circadian clock. C. elegans has been known to inherit a per homologue, lin-42. Levels of lin-42 mRNA oscillate synchronously with approximately 6-hr molting cycle at the larvae stage and become flat at the adult stage. We have succeeded to show a convincing circadian rhythm of the locomotor activity in adult C. elegans, using the automatic device (Bug-tracker) to record footprints of an isolated animal. The rhythm exhibit characteristics such that: 1) the nematode in the larva stage exhibit a behavioral rhythm with a period shorter than 24 hours ; 2) the rhythm in the adulthood can be entrained at a 12-h light and 12-h dark cycle (LD) ; 3) the rhythm free runs with the period of about 24 hour in the range of temperature between 15 and 25 degrees C in constant dark (DD) ; 4) the rhythm is entrained to 180 degrees reversed LD(=DL) with repeated L phase or D phase on an LD. These result prove that the nematode inherits a convincing circadian clock with caracteristics common to the circadian clocks of other animal. Also suggest a possibility that per and relating clock genes are not indispensable for the circadian rhythm in the animal kingdom and that further universal system should lie behind, which should even governs the clock genes. To identify the universal circadian system, we are examining the behavioral rhythms in nematodes with knockout and/or rescued genes considerable to be involved in the circadian timekeeping, using a newly devised system with multi-channel, which enables us to measure the circadian behavioral rhythms of a number of isolated nematodes at once. The nematode will provide a novel excellent model for the molecular study of circadian clock.