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Biosynthesis of the Caenorhabditis elegans dauer pheromone.

ABSTRACT: To sense its population density and to trigger entry into the stress-resistant dauer larval stage, Caenorhabditis elegans uses the dauer pheromone, which consists of ascaroside derivatives with short, fatty acid-like side chains. Although the dauer pheromone has been studied for 25 years, its biosynthesis is completely uncharacterized. The daf-22 mutant is the only known mutant defective in dauer pheromone production. Here, we show that daf-22 encodes a homolog of human sterol carrier protein SCPx, which catalyzes the final step in peroxisomal fatty acid beta-oxidation. We also show that dhs-28, which encodes a homolog of the human d-bifunctional protein that acts just upstream of SCPx, is also required for pheromone production. Long-term daf-22 and dhs-28 cultures develop dauer-inducing activity by accumulating less active, long-chain fatty acid ascaroside derivatives. Thus, daf-22 and dhs-28 are required for the biosynthesis of the short-chain fatty acid-derived side chains of the dauer pheromone and link dauer pheromone production to metabolic state.

SUBMITTER: Butcher RA

PROVIDER: S-EPMC2631283 | biostudies-literature |

REPOSITORIES: biostudies-literature

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A potent dauer pheromone component in Caenorhabditis elegans that acts synergistically with other components.

Project description:In the model organism Caenorhabditis elegans, the dauer pheromone is the primary cue for entry into the developmentally arrested, dauer larval stage. The dauer is specialized for survival under harsh environmental conditions and is considered "nonaging" because larvae that exit dauer have a normal life span. C. elegans constitutively secretes the dauer pheromone into its environment, enabling it to sense its population density. Several components of the dauer pheromone have been identified as derivatives of the dideoxy sugar ascarylose, but additional unidentified components of the dauer pheromone contribute to its activity. Here, we show that an ascaroside with a 3-hydroxypropionate side chain is a highly potent component of the dauer pheromone that acts synergistically with previously identified components. Furthermore, we show that the active dauer pheromone components that are produced by C. elegans vary depending on cultivation conditions. Identifying the active components of the dauer pheromone, the conditions under which they are produced, and their mechanisms of action will greatly extend our understanding of how chemosensory cues from the environment can influence such fundamental processes as development, metabolism, and aging in nematodes and in higher organisms.

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A Forward Genetic Screen for Molecules Involved in Pheromone-Induced Dauer Formation in Caenorhabditis elegans.

Project description:Animals must constantly assess their surroundings and integrate sensory cues to make appropriate behavioral and developmental decisions. Pheromones produced by conspecific individuals provide critical information regarding environmental conditions. Ascaroside pheromone concentration and composition are instructive in the decision of Caenorhabditis elegans to either develop into a reproductive adult or enter into the stress-resistant alternate dauer developmental stage. Pheromones are sensed by a small set of sensory neurons, and integrated with additional environmental cues, to regulate neuroendocrine signaling and dauer formation. To identify molecules required for pheromone-induced dauer formation, we performed an unbiased forward genetic screen and identified phd (pheromone response-defective dauer) mutants. Here, we describe new roles in dauer formation for previously identified neuronal molecules such as the WD40 domain protein QUI-1 and MACO-1 Macoilin, report new roles for nociceptive neurons in modulating pheromone-induced dauer formation, and identify tau tubulin kinases as new genes involved in dauer formation. Thus, phd mutants define loci required for the detection, transmission, or integration of pheromone signals in the regulation of dauer formation.

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The transcriptional signatures of Caenorhabditis elegans dauer larvae

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.

2024-08-15 | GSE274872 | GEO

Pristionchus pacificus and Caenorhabditis elegans: Dauer and Dauer exit versus mix-stage comparisons

Project description:This SuperSeries is composed of the SubSeries listed below.

2012-03-22 | GSE36644 | GEO

Bacterial fatty acids enhance recovery from the dauer larva in Caenorhabditis elegans.

Project description:The dauer larva is a specialized dispersal stage in the nematode Caenorhabditis elegans that allows the animal to survive starvation for an extended period of time. The dauer does not feed, but uses chemosensation to identify new food sources and to determine whether to resume reproductive growth. Bacteria produce food signals that promote recovery of the dauer larva, but the chemical identities of these signals remain poorly defined. We find that bacterial fatty acids in the environment augment recovery from the dauer stage under permissive conditions. The effect of increased fatty acids on different dauer constitutive mutants indicates a role for insulin peptide secretion in coordinating recovery from the dauer stage in response to fatty acids. These data suggest that worms can sense the presence of fatty acids in the environment and that elevated levels can promote recovery from dauer arrest. This may be important in the natural environment where the dauer larva needs to determine whether the environment is appropriate to support reproductive growth following dauer exit.

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Molecular strategies of the Caenorhabditis elegans dauer larva to survive extreme desiccation.

Project description:Massive water loss is a serious challenge for terrestrial animals, which usually has fatal consequences. However, some organisms have developed means to survive this stress by entering an ametabolic state called anhydrobiosis. The molecular and cellular mechanisms underlying this phenomenon are poorly understood. We recently showed that Caenorhabditis elegans dauer larva, an arrested stage specialized for survival in adverse conditions, is resistant to severe desiccation. However, this requires a preconditioning step at a mild desiccative environment to prepare the organism for harsher desiccation conditions. A systems approach was used to identify factors that are activated during this preconditioning. Using microarray analysis, proteomics, and bioinformatics, genes, proteins, and biochemical pathways that are upregulated during this process were identified. These pathways were validated via reverse genetics by testing the desiccation tolerances of mutants. These data show that the desiccation response is activated by hygrosensation (sensing the desiccative environment) via head neurons. This leads to elimination of reactive oxygen species and xenobiotics, expression of heat shock and intrinsically disordered proteins, polyamine utilization, and induction of fatty acid desaturation pathway. Remarkably, this response is specific and involves a small number of functional pathways, which represent the generic toolkit for anhydrobiosis in plants and animals.

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Global analysis of dauer gene expression in Caenorhabditis elegans

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

2005-08-20 | GSE3169 | GEO

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