6 Papers found (0.008 seconds)

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]

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.

Sergio H Simonetta et al. (2007) International Worm Meeting "Circadian behavior of C. elegans: Automated tracking of locomotor activity."

Sergio H Simonetta, Diego A Golombek

[

International Worm Meeting,

2007]

The automated tracking of locomotor behaviors is a fundamental tool for genetics, pharmacological and physiological studies. In this work we show the development and implementation of a new tracking system based on infrared microbeam scattering for the study of locomotor behavior in C. elegans. Adult worms were cultured individually in 96-plate wells (U-shape) with liquid medium, and their locomotor activity was tracked for more than 15 days. We tested E. coli OP50 solution, Leibovitzs L15 and CeMM culture medium, being CeMM the optimal for long-term experiments. To prevent self-reproduction, 40uM of Fluorodeoxyuridine (FuDR) was added at L4 stage. We used 1.5x Antibiotic-Antimycotic, silicone oil, and scotch tape to avoid contamination and desiccation. Since circadian rhythmicity was recently reported in C. elegans (1,2), we employed this method to characterize locomotor activity rhythms. Circadian rhythms were found to be entrained by diurnal light cycles (light:Dark 12:12 400:0 lux) peaking at the end of the night, analyzed by phase histograms. When entrained by temperature cycles they show maximum activity at the middle of the day . Indeed, when worms are entrained to high amplitude cycles of temperature (delta T=4 C) locomotor activity appears to be masked, observed as a significative decrease in locomotion for 1 hour when the temperature decreases. These rhythms still persist in constant conditions (continuous darkness, temperature set at 16; 18 or 20 C), with an average period of 23 h (37.5% of the worms exhibited significant circadian rhythms as analyzed by Lomb-Scargle periodogram), but with a high variation in their inter-individual period. Our system is therefore capable of determining circadian behaviors in this model and might be useful for its genetic and neural characterization. 1. Kippert F et al . 2002. Current biology 2. Saigusa T et al . 2002. Current biology.

Tom Janssen et al. (2007) International Worm Meeting "The clock ticks on with the discovery of PDF and its receptors in Caenorhabditis elegans."

Inge Mertens, Steven J. Husson, Johan Geysen, Gert Jansen, Liliane Schoofs, Tom Janssen, Suzanne Rademakers, Kris Ver Donck, Karen Verstraelen, Marleen Lindemans

[

International Worm Meeting,

2007]

Circadian clocks control the daily rhythms in physiology and behavior of organisms ranging from bacteria to mammals, as an adaptation to the earths 24-hour rotation. The basic mechanism underlying these circadian rhythms follows a similar general plan across the phylogenetic spectrum. In the fruit fly Drosophila melanogaster, a neuropeptide called pigment dispersing factor (PDF) is the key outgoing signal of the circadian system. Caenorhabditis elegans also exhibits a convincing circadian rhythm in locomotor behavior and in resistance to hyperosmotic stress (1-2), but the underlying mechanism still remains elusive. Here, we report the identification and characterization of a neuropeptide signaling system, similar to the key output signals of the circadian clock in Drosophila melanogaster. We identified three pigment dispersing factors (Ce-PDF-1a, b and Ce-PDF-2) and their G protein-coupled receptors in C. elegans, and demonstrate their involvement in the regulation of locomotor behavior (3). The three C. elegans PDFs were isolated from a peptide-enriched extract and identified by LC-MS. GFP fusions show that they are primarily expressed in specific head and tail neurons. The three identified GPCRs all display a specific affinity for each of the 3 Ce-PDFs. Receptor expression was observed in particular neurons and all somatic muscle cells. Many of the PDF and/or PDF-receptor expressing cells play a role in the integration of environmental stimuli and the control of locomotion. Overexpression of PDF-2 phenocopies the locomotor defects of a PDF-1 null mutant, suggesting that they elicit antagonistic effects on locomotion. These findings indicate that the Ce-PDFs may be a key outgoing signal in the C. elegans circadian clock, changing the locomotor behavior by acting through these (muscle) receptors. Our findings suggest that PDF signaling might be well conserved during evolution, at least in invertebrates (3). 1. Kippert,F. et al. Caenorhabditis elegans has a circadian clock. Curr. Biol. 12, R47-R49 (2002). 2. Saigusa,T. et al. Circadian behavioural rhythm in Caenorhabditis elegans. Curr. Biol. 12, R46-R47 (2002). 3. Janssen et al. The clock ticks on with the discovery of PDF and its receptors in the nematode Caenorhabditis elegans. Neuron submitted.

van der Linden, Alexander M. et al. (2009) International Worm Meeting "Temperature and light-entrained circadian rhythms in C. elegans."

Sengupta, Piali, van der Linden, Alexander M., Kadener, Sebastian, Rosbash, Michael

[

International Worm Meeting,

2009]

Circadian control of feeding is critical for animals to properly adapt to their environment, and for optimal development. However, the nature of this interaction and its relationship to metabolism is poorly understood. C. elegans has proved to be an extremely powerful model for understanding the molecular basis of feeding behavior, but it is unknown whether C. elegans feeding is under circadian control. Although circadian locomotory rhythms were described in C. elegans previously (1), these observations have been difficult to replicate, and no rhythmically expressed clock or clock-output genes in C. elegans have been identified. We set out to not only investigate the yet unidentified circadian clock in C. elegans, but to also explore the interaction between circadian clocks, metabolism and feeding behaviors. Since circadian transcripts exhibit rhythmic oscillations, genome-wide expression profiling experiments are a powerful approach to identify clock and clock-output genes. We used microarrays and a series of data analysis algorithms to identify circadian-regulated genes under photo- and thermocycling conditions in C. elegans. We identified subsets of candidate clock-output genes that exhibit robust rhythmic expression with 24 hr periodicity under either light-dark or warm-cold conditions, as well as in constant dark-dark or cold-cold conditions following entrainment. Our results indicate that thermocycles directly evoke a global expression response broader than photocycles, and that a subset of genes undergo cycling in a circadian manner. Verification of microarray data via qRT-PCR suggests that these genes may represent bona fide cycling genes. These sets include molecules predicted to regulate metabolic processes, suggesting that feeding - an activity closely related to energy metabolism - may be under circadian control. Preliminary results suggest that tax-2, which is important for thermo- and phototaxis (2) is necessary for the cycling of these genes. We have also developed a reporter assay system to monitor rhythmic circadian gene expression, and we are planning to use this system in genetic screens to define the core clock components. Moreover, we are determining whether feeding behavior is under circadian control, and whether food signals can entrain the clock. Since it is likely that the molecular components of the C. elegans clock are distinct from those of other organisms, this work is also expected to provide information regarding the evolution of circadian clocks. 1) Saigusa et al, 2002; Simonetta & Golombek, 2007; 2) Coburn et al, 1996; Ward et al, 2008.

A.M. van der Linden et al. (2007) International Worm Meeting "Temperature-entrained circadian rhythms in C. elegans."

P. Sengupta, S. Kadener, M. Rosbash, A.M. van der Linden

[

International Worm Meeting,

2007]

The circadian clock is an internal timing mechanism that enables organisms to respond to, and even anticipate changing environmental conditions associated with rotation of the earth. The output of these clocks results in circadian rhythms, which oscillate with circa 24 hr periods and control multiple aspects of behavior and physiology. Circadian rhythms can be entrained by daily environmental signals (zeitgebers). Although the role of light is well understood, temperature can also entrain rhythms via as yet poorly understood mechanisms. Following entrainment, circadian rhythms persist for days, even months under free-running conditions. The molecular mechanisms required for the function of the core clock have been studied extensively in cyanobacteria, Neurospora, Arabidopsis, Drosophila and mouse. Surprisingly, the circadian clock in C. elegans is poorly characterized, and circadian phenotypes remain unverified. Although reported circadian behaviors include locomotory and hyperosmotic stress rhythms following light/dark entrainments (1), no clock or clock-output genes have been identified. Homologs of animal clock genes are represented in the genome of C. elegans, but their only certain function is to regulate developmental timing. Thus, the nature, and even existence of a bona fide C. elegans circadian clock remains uncertain. Because C. elegans is subjected to diurnal temperature fluctuations in the soil, we focused on this zeitgeber and subjected growth-synchronized populations of C. elegans to 12:12 hr cycles of 25:15C. RNA was isolated from these populations during the final day of entrainment and subsequent day of free-run at 15C and hybridized to Affymetrix chips containing >19,000 predicted C. elegans genes. So far, we identified at least 135 genes that cycle with >2.0 amplitude during entrainment and/or free-running experiments. Interestingly, homologs of the clock genes lin-42 (Period) and aha-1 (Clock/Cycle) do not cycle. To validate the microarray data, we analyzed the expression levels of a number of clock-output genes using quantitative RT-PCR. Expression data from qRT-PCR mirrored the expression changes shown via microarray data analysis, suggesting that these genes may represent bona fide cycling genes. Our results indicate that a subset of C. elegans genes undergo cycling in a circadian manner, and that these rhythms can be entrained by temperature. Since it is likely that the molecular components of the C. elegans clock are distinct from those of other organisms, C. elegans provides a new system for understanding circadian clocks as well as the evolution of circadian mechanisms. 1) Kippert et al, 2002; Saigusa et al, 2002; Simonetta & Golombek, 2007.