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. Overall design: total RNA profiles of L4 wild type (N2) and flp-6 mutant Caenorhabditis elegans were generated by deep sequencing using Illumina Solexa.
Project description:To evaluate the gene expression levels dependent on cultivated temperature (15-degree only or 25-degree after 15-degree grown) in wild type (N2 strain) and daf-2mutant Worms were cultivated at 15-degree from egg to adult or at 25-degree for 12 hours after 15-degree grown until young adult, then total RNA was collected
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. Overall design: 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:C. elegans exhibits thermotaxis, where most of the animals that had been cultivated at a particular temperature ranging from 15°C to 25°C for a few hours with a food source and then placed on a thermal gradient for an hour migrate to the cultivation temperature. In addition, animals that were previously conditioned to migrate to a certain temperature are capable of migrating to a new cultivation temperature a few hours after the cultivation temperature was shifted to the new temperature To gain the detailed molecular insight into thermotactic behavior, the genome-wide microarray analysis during behavioral conditioning was performed. We compared the transcriptional profile of animals conditioned to migrate to the new temperature 17°C with that of animals conditioned to migrate to the previous temperature 23°C Synchronized adult wild-type animals cultivated at 23 degrees were selected for RNA extraction and hybridization on Affymetrix microarrays.