Project description:Genomic response of C. elegans after infection with Microbacterium nematophilum.<br><br>The interaction between the nematode Caenorhabditis elegans and a Gram-positive bacterial pathogen, Microbacterium nematophilum, provides a model for an innate immune response in nematodes. This pathogen adheres to the rectal and post-anal cuticle of the worm, causing slowed growth, constipation, and a defensive swelling response of rectal hypodermal cells. To explore the genomic responses that the worm activates after pathogenic attack we used microarray analysis of transcriptional changes induced after 6 hr infection, comparing virulent with avirulent infection.
Project description:In this study, we combined metabolic reconstruction, growth assays, metabolome and transcriptome analyses to obtain a global view of the sulfur metabolic network and of the response to sulfur availability in Brevibacterium aurantiacum. In agreement with the growth of B. aurantiacum in the presence of sulfate and cystine, the metabolic reconstruction showed the presence of a sulfate assimilation pathway and of thiolation pathways that produce cysteine (cysE and cysK) or homocysteine (metX and metY) from sulfide, of at least one gene of the transsulfuration pathway (aecD) and of genes encoding three MetE-type methionine synthases. We also compared the expression profiles of B. aurantiacum ATCC9175 during sulfur starvation and in the presence of sulfate, cystine or methionine plus cystine. In sulfur starvation, 690 genes including 21 genes involved in sulfur metabolism and 29 genes encoding amino acids and peptide transporters were differentially expressed. We also investigated changes in pools of sulfur-containing metabolites and in expression profiles after growth in the presence of sulfate, cystine or methionine plus cystine. The expression of genes involved in sulfate assimilation and cysteine synthesis was repressed in presence of cysteine, while the expression of metX, metY, metE1, metE2 and BL613 encoding a probable cystathionine-γ-synthase decreased in the presence of methionine. We identified three ABC transporters: two stronger transcribed during cysteine limitation and one during methionine depletion. Finally, the expression of genes encoding a methionine γ-lyase, BL929, and a methionine transporter (metPS) was induced in the presence of methionine, in conjunction with a significant increase of volatile sulfur compounds production. This SuperSeries is composed of the SubSeries listed below.
