Project description:Synchronized C. elegans cultures of three geontypes -- wildype N2, daf-2(e1370) and sma-6(wk7) -- were prepared using standard techniques (http://cmgm.stanford.edu/~kimlab/index_methods.html). Live young adult worms were split between NG plates pre-seeded with the non-pathogenic E. coli strain OP50 or the Pseudomonas aeruginosa clinical isolate PA14 and incubated at 25C for 4 or 24 hours before harvesting. This experiment was repeated at least three times on independent occasions. cDNA probes were prepared from experimental samples and from reference mRNA extracted from mixed stage wild type worms grown at 25C, and were labeled with Cy3 or Cy5, as indicated. A reference experiement design type is where all samples are compared to a common reference. Elapsed Time: Time Infection: Exposure to the non-pathogenic E. coli strain OP50 or to the pathogenic Pseudomonas aeruginosa strain PA14 Strain Name: C. elegans wildtype strain N2 or the immune pathway mutants daf-2(e1370) or sma-6(wk7) Keywords: reference_design
Project description:Analysis of differential gene expression in C. elegans adults exposed to three different bacteria: E. coli strain OP50, wild-type P. aeruginosa PA14 and gacA mutant PA14. Samples were analyzed at 4 hours and 8 hours after exposure to the different bacteria. These studies identified C. elegans genes induced by pathogen infection. Keywords: Time course, response to pathogen infection
Project description:Synchronized C. elegans cultures of three geontypes -- wildype N2, daf-2(e1370) and sma-6(wk7) -- were prepared using standard techniques (http://cmgm.stanford.edu/~kimlab/index_methods.html). Live young adult worms were split between NG plates pre-seeded with the non-pathogenic E. coli strain OP50 or the Pseudomonas aeruginosa clinical isolate PA14 and incubated at 25C for 4 or 24 hours before harvesting. This experiment was repeated at least three times on independent occasions. cDNA probes were prepared from experimental samples and from reference mRNA extracted from mixed stage wild type worms grown at 25C, and were labeled with Cy3 or Cy5, as indicated. A reference experiement design type is where all samples are compared to a common reference. Elapsed Time: Time Infection: Exposure to the non-pathogenic E. coli strain OP50 or to the pathogenic Pseudomonas aeruginosa strain PA14 Strain Name: C. elegans wildtype strain N2 or the immune pathway mutants daf-2(e1370) or sma-6(wk7) Keywords: reference_design Computed
Project description:Very little is known about how animals discriminate pathogens from innocuous microbes. To address this question, we examined infection-response gene induction in the nematode Caenorhabditis elegans. We focused on genes that are induced in C. elegans by infection with the bacterial pathogen Pseudomonas aeruginosa, but are not induced by an isogenic attenuated gacA mutant. Most of these genes are induced independently of known immunity pathways. We generated a GFP reporter for one of these genes, infection response gene 1 (irg-1), which is induced strongly by wild-type P. aeruginosa strain PA14, but not by other C. elegans pathogens or by other wild-type P. aeruginosa strains that are weakly pathogenic to C. elegans. To identify components of the pathway that induces irg-1 in response to infection, we performed an RNA interference screen of C. elegans transcription factors. This screen identified zip-2, a bZIP transcription factor that is required for inducing irg-1, as well as several other genes, and is important for defense against infection by P. aeruginosa. These data indicate that zip-2 is part of a specialized pathogen response pathway that is induced by virulent strains of P. aeruginosa and provides defense against this pathogen. Analysis of differential gene expression in adult N2 C. elegans treated with L4440 control RNAi or zip-2 RNAi, either uninfected (feeding on E. coli) or infected with P. aeruginosa PA14; samples were analyzed after 4 hours of infection
Project description:The nematode Caenorhabditis elegans feeds on microbes in its natural environment. Some of these microbes are pathogenic and thus harmful to C. elegans. To minimize resulting fitness reductions, C. elegans has evolved various defence mechanisms including behavioural responses (e.g. avoidance behaviour) that reduce contact with the infectious microbes. In this study, we characterized the genetic architecture of natural variation in C. elegans avoidance behaviour against the infectious stages of the Gram-positive bacterium Bacillus thuringiensis. We performed an analysis of quantitative trait loci (QTLs) using recombinant inbred lines (RILs) and introgression lines (ILs) generated from a cross of two genetically as well as phenotypically distinct natural isolates N2 and CB4856. The analysis identified several QTLs that underlie variation in the behavioural response to pathogenic and/or non-pathogenic bacteria. One of the candidates is the npr-1 gene. This gene encodes a homolog of the mammalian neuropeptide receptor. Npr-1 was previously indicated to fully contribute to behavioural defence against the Gram-negative bacterium Pseudomonas aeruginosa and food patch-leaving behaviour on Escherichia coli. Interestingly, in our study, npr-1 is not the only gene mediating avoidance behaviour toward Bacillus thuringiensis. Moreover, our functional analyses show that npr-1 alleles appear to influence survival and avoidance behaviour toward Bacillus thuringiensis in exactly the opposite way than toward Pseudomonas aeruginosa. Our findings highlight the role of npr-1 in fine-tuning nematode behaviour in an ecological context depending on the microbe to which C. elegans is exposed. These opposite phenotypes reflect the diversity in innate immunity to pathogens. To understand the mechanism involved in these opposite phenotypes, we carried out a whole-genome transcriptomics study by RNA-Sequencing. This study includes two pathogens: Pseudomonas aeruginosa PA14 and Bacillus thuringiensis B-18247 (BT247), two strains: N2 and npr-1 (ur89), two time points (12 and 24h) and standard lab food E. coli OP50 as control.
Project description:To gain insights into the mechanisms by which RC301 compensates for the deficiency in the NPR-1 controlled immune and behavioral responses of strain DA650, we determine the whole-genome expression profile of these two strains upon exposure to Pseudomonas aeruginosa strain PA14
Project description:Analysis of differential gene expression in C. elegans adults exposed to three different bacteria: E. coli strain OP50, wild-type P. aeruginosa PA14 and gacA mutant PA14. Samples were analyzed at 4 hours and 8 hours after exposure to the different bacteria. These studies identified C. elegans genes induced by pathogen infection. Experiment Overall Design: Three independent biological replicates were isolated for each treatment. All treatments were performed in parallel.
Project description:C-type lectin-like domain (CTLD) encoding genes are highly diverse in C. elegans, comprising a clec gene family of 283 members. Since vertebrate CTLD proteins have characterized functions in defense responses against pathogens and since expression of C. elegans clec genes is pathogen-dependent, it is generally assumed that clec genes function in C. elegans immune defenses. In this study we challenged this assumption and focused on the C. elegans clec gene clec-4, whose expression is highly upregulated upon infection with various pathogens. We tested the involvement of clec-4 in the defense response to infection with Pseudomonas aeruginosa PA14, Bacillus thuringiensis BT18247, and the natural pathogen Serratia rubidaea MYb237. Contrary to our expectation clec-4(ok2050) mutant worms were not more susceptible to pathogen infection than wildtype worms. To explore potential redundant function between different C. elegans clec genes, we investigated expression of several clec-4 paralogs, finding that clec-4, clec-41, and clec-42 expression shows similar infection-dependent changes and co-localizes to the intestine. We found that only clec-42 is required for the C. elegans defense response to BT18247 infection and that clec-4 genetically interacts with clec-41 and clec-42. The exact role of clec-4 in pathogen defense responses however remains enigmatic. Our results further indicate that a complex interplay between different clec genes regulates C. elegans defense responses.