Project description:We find that the 'high-confidence oscillating' genes initiate oscillations similarly as after release from L1 dauer. We performed high-throughput RNA sequencing on worms that were synchronously released from the dauer stage by refeeding on OP50. In particular, we investigate oscillatory gene expression as described in Hendriks et al., 2014 (doi: 10.1016/j.molcel.2013.12.013) and observe the re-initiation of oscillatory gene expression from stable expression with a time delay upon dauer exit. Experimental observation of the transitions between non-oscillatory and oscillatory states during the first 5 hours after dauer exit reveals that the oscillatory gene expression is arrested in a specific oscillator phase, similar to the observation we make in animals released from L1 arrest (see Meeuse et al., 2020, doi: https://doi.org/10.1101/755421).
Project description:Under adverse environmental conditions, nematodes arrest into dauer, an alternative developmental stage for diapause. Dauers endure unfavorable environment and interact with host animals to access favorable environments, thus playing a critical role in the survival of both free-living and parasitic nematodes. Here, we discovered that in Caenorhabditis elegans, daf-42 is essential for development into dauer stage, as the null mutant shows lethal phenotype during dauer entry. To examine the transcriptional changes accompanied by the absence of DAF-42 during dauer entry, we performed RNA-sequencing on daf-2 and daf-2; daf-42 worms at 52 hours after egg laying (HAE) and 60 HAE, the time at which 0% and about 40% of daf-2; daf-42 mutants form dead dauer at 25 degrees Celcius, respectively. daf-2 control worms develop into dauer stage after 60 HAE, and half of its population develop into dauer by 72 HAE, when raised at 25 degrees Celcius.
Project description:Both plasticity and robustness are pervasive features of developmental programs. The dauer in Caenorhabditis elegans is an alternative to the third larval stage of the nematode and is an example of phenotypic plasticity. The dauer is an arrested, hypometabolic state that undergoes dramatic changes in gene expression compared to conspecifics that continue development, and can be induced by several adverse environments or genetic mutations that act as independent and parallel inputs into the larval developmental program. However, given the different genetic or environmental triggers that can induce dauer, gene expression in dauer larvae could be invariant or vary depending on the larvae’s route into dauer entry; this question has not been examined. Here we use RNA-sequencing to characterize gene expression in dauer larvae induced to arrest development in response to different stimuli. By assessing the variance in the expression levels of all genes and computing the Spearman's rank-order correlation of gene expression within several Gene Ontologies (GO) and gene networks, we find that the expression patterns of most genes, except for those that act in specific defense and metabolic pathways, are strongly correlated between the different dauer larvae, suggestive of transcriptional robustness. We speculate that the transcriptional robustness of core dauer pathways allows for the buffering of variation in the expression of genes involved in their response to the environment, allowing the different dauers to be better suited to survive in and exploit different niches.
Project description:These are the 94 microarray experiments that are published in the paper: John Wang and Stuart K. Kim. Global analysis of dauer gene expression in Caenorhabditis elegans, Development 2003 130: 1621-1634. There are 94 individual microarray experiments divided into 3 broad experiments. The first experiment is a time course of dauer exit; each time course is labeled as "Dauer MTC#". The second experiment is a time course of L1 development after starvation arrest; each time couse is labeled "L1 MTC#". The final experiment is a comparison of pure dauers (0 hours) versus 12 hours after dauer exit and are labeled "Dauer Adjust". Every time course was repeated 4 times (#N)however for the dauer 4 and 7 hour time points there are only 3 replicates. For instance, all the time points labeled as "Dauer MTC#1" are from the same starting pool of dauer worms that were aliquoted into 10 fractions and analyzed at the time indicated. Every sample is compared to a common reference RNA that is used throughout all the hybridizations. In some cases there is a "-2" after the hour designation; this means the first hybridization failed for some technical reason and thus the second hybridization (same RNA) is reported. Groups of assays that are related as part of a time series. Keywords: time_series_design
Project description:Animals change developmental fates in response to external cues. In the nematode Caenorhabditis elegans, unfavorable environmental conditions induce a state of diapause known as dauer by inhibiting the conserved DAF-2 insulin-like signaling (ILS) pathway through incompletely understood mechanisms. We previously established a role for the C. elegans dosage compensation protein DPY-21 in the control of dauer arrest and DAF-2 ILS. Here we show that dosage compensation acts through the histone H4 lysine 20 methyltransferase SET-4 to promote dauer arrest in part by repressing the X-linked ins-9 gene, which encodes a new agonist insulin-like peptide (ILP) expressed specifically in the paired ASI sensory neurons that are required for dauer bypass. ins-9 repression in dauer-constitutive mutants requires DPY-21, SET-4, and the FoxO transcription factor DAF-16, which is the main target of DAF-2 ILS. In contrast, autosomal genes encoding major agonist ILPs that promote reproductive development are not repressed by DPY-21, SET-4, or DAF-16/FoxO. Our results implicate the dosage compensation machinery as a sensory rheostat that reinforces developmental fates in response to environmental cues by modulating autocrine and paracrine DAF-2 ILS.
Project description:N2 worms were subjected to control (well-fed), short-term dauer (6 d), or long-term dauer (40 - 49 d) conditions. Worms were recovered and maintained well-fed for 3 generations. F3 progeny were collected as fed or starved L1 larvae.
Project description:This SuperSeries is composed of the following subset Series: GSE30977: C. elegans: Dauers and Dauer-Exit at 12 hour time-point vs. Mix-stage worms GSE31861: P. pacificus : Dauers and Dauer-Exit at 12 hour time-point vs. Mix-stage worms Refer to individual Series
Project description:Seperate White and Opaque Candida albicans populations were exposed to a temperature shift from 25 degrees to 37 degrees. Samples were then harvested at various time points to follow the effects of the shift on the two cell types, particularly the opaque cell type which switches to the white cell type after several hours at 37 degrees.