Project description:Most organisms have an endogenous circadian clock that is synchronized to environmental signals such as light and temperature. Although circadian rhythms have been described in the nematode C. elegans at the behavioral level, these rhythms appear to be relatively non-robust. Moreover, in contrast to other animal models, no circadian transcriptional rhythms have been identified. Thus, whether this simple nematode contains a bona fide circadian clock remains an open question. We used microarray experiments to identify light- and temperature-regulated transcriptional rhythms in C. elegans, and show that subsets of these transcripts are regulated in a circadian manner. In addition, we find that light and temperature also globally drive the expression of many genes, indicating that C. elegans exhibits systemic responses to these stimuli. Populations of growth-synchronized wild-type C. elegans L1 larvae were entrained for 5 days until adulthood to 12:12 hr light/dark (LD) cycles (500-1000 lux) at a constant temperature of 18°C, or for 4 days to 12:12 hr temperature cycles (25:15°C - warm/cold or WC) in constant darkness. RNA was collected every 4 hrs during the last entrainment and the subsequent free-running days and analyzed via hybridization of Affymetrix GeneChips. L4 larvae were transferred to FUDR-containing plates to inhibit embryonic development.
Project description:Most organisms have an endogenous circadian clock that is synchronized to environmental signals such as light and temperature. Although circadian rhythms have been described in the nematode C. elegans at the behavioral level, these rhythms appear to be relatively non-robust. Moreover, in contrast to other animal models, no circadian transcriptional rhythms have been identified. Thus, whether this simple nematode contains a bona fide circadian clock remains an open question. We used microarray experiments to identify light- and temperature-regulated transcriptional rhythms in C. elegans, and show that subsets of these transcripts are regulated in a circadian manner. In addition, we find that light and temperature also globally drive the expression of many genes, indicating that C. elegans exhibits systemic responses to these stimuli.
Project description:Young adult fer-15;fem-1 Caenorhabditis elegans were infected with Staphylococcus aureus for 8 h to determine the transcriptional host response to Staphylococcus aureus. Analysis of differential gene expression in C. elegans young adults exposed to two different bacteria: E. coli strain OP50 (control), wild-type Staphylococcus aureus RN6390. Samples were analyzed at 8 hours after exposure to the different bacteria. These studies identified C. elegans genes induced by pathogen infection. Keywords: response to pathogen infection, innate immunity, host-pathogen interactions
Project description:Temperature is a prominent environmental stimulus that influences life span. Previous studies indicate that in Caenorhabditis elegans, thermosensory perception in the AFD neuron maintains life span at warm temperatures. How thermosensation is translated into neuronal signals that shape aging remains elusive. We found that the Caenorhabditis elegans CREB crh-1, as well as several key genes in AFD thermosensory transduction, were specifically required for normal life span at warm temperatures. crh-1 acted in the AFD to increase transcription of the CRE-containing neuropeptide gene flp-6 in a temperature-dependent manner. Both crh-1 and flp-6 were necessary and sufficient for longevity at warm temperatures, and their effects depended on the AIY interneuron. Moreover, flp-6 signaling downregulated ins-7/insulin and several insulin pathway genes, whose activity compromised life span. We postulate that temperature experience is integrated in the thermosensory neurons to generate CREB-dependent neuropeptide signals that antagonize insulin signaling and promote temperature-specific longevity.