Project description:This SuperSeries is composed of the following subset Series: GSE11437: Expression QTL mapping of Toxoplasma gondii genes, Bradyzoite array GSE11514: Expression QTL mapping of Toxoplasma gondii genes, Tachyzoite array Keywords: SuperSeries Refer to individual Series
Project description:Toxoplasma gondii is an intracellular parasite with a significant impact on human health, especially in cases where individuals are immunocompromised (e.g., due to HIV/AIDS). In Europe and North America only a few clonal genotypes appear to be responsible for the vast majority of Toxoplasma infections, and these clonotypes have been intensely studied to identify strain-specific phenotypes that may play a role in the manifestation of more severe disease. To identify and genetically map strain-specific differences in gene expression, we have carried out expression quantitative trait locus (eQTL) analysis on Toxoplasma gene expression phenotypes using spotted cDNA microarrays. This led to the identification of 16 Toxoplasma genes that had significant and mappable strain-specific variation in hybridization intensity. While the analysis should identify both cis and trans-mapping hybridization profiles, we only identified loci with strain-specific hybridization differences that are most likely due to differences in the locus itself (i.e., cis-mapping). Interestingly, a larger number of these cis-mapping genes than would be expected by chance encode either confirmed or predicted secreted proteins, many of which are known to localize to the specialized secretory organelles characteristic of members of the phylum Apicomplexa. For 6 of the cis-mapping loci we determined if the strain-specific hybridization differences were due to true transcriptional differences or rather strain-specific differences in hybridization efficiency because of extreme polymorphism and/or deletion, and we found examples of both scenarios. Keywords: eQTL mapping; virulence; Toxoplasma gondii
Project description:Toxoplasma gondii is an intracellular parasite with a significant impact on human health, especially in cases where individuals are immunocompromised (e.g., due to HIV/AIDS). In Europe and North America only a few clonal genotypes appear to be responsible for the vast majority of Toxoplasma infections, and these clonotypes have been intensely studied to identify strain-specific phenotypes that may play a role in the manifestation of more severe disease. To identify and genetically map strain-specific differences in gene expression, we have carried out expression quantitative trait locus (eQTL) analysis on Toxoplasma gene expression phenotypes using spotted cDNA microarrays. This led to the identification of 16 Toxoplasma genes that had significant and mappable strain-specific variation in hybridization intensity. While the analysis should identify both cis and trans-mapping hybridization profiles, we only identified loci with strain-specific hybridization differences that are most likely due to differences in the locus itself (i.e., cis-mapping). Interestingly, a larger number of these cis-mapping genes than would be expected by chance encode either confirmed or predicted secreted proteins, many of which are known to localize to the specialized secretory organelles characteristic of members of the phylum Apicomplexa. For 6 of the cis-mapping loci we determined if the strain-specific hybridization differences were due to true transcriptional differences or rather strain-specific differences in hybridization efficiency because of extreme polymorphism and/or deletion, and we found examples of both scenarios. Keywords: eQTL mapping; virulence; Toxoplasma gondii
Project description:Toxoplasma gondii is an intracellular parasite with a significant impact on human health, especially in cases where individuals are immunocompromised (e.g., due to HIV/AIDS). In Europe and North America only a few clonal genotypes appear to be responsible for the vast majority of Toxoplasma infections, and these clonotypes have been intensely studied to identify strain-specific phenotypes that may play a role in the manifestation of more severe disease. To identify and genetically map strain-specific differences in gene expression, we have carried out expression quantitative trait locus (eQTL) analysis on Toxoplasma gene expression phenotypes using spotted cDNA microarrays. This led to the identification of 16 Toxoplasma genes that had significant and mappable strain-specific variation in hybridization intensity. While the analysis should identify both cis and trans-mapping hybridization profiles, we only identified loci with strain-specific hybridization differences that are most likely due to differences in the locus itself (i.e., cis-mapping). Interestingly, a larger number of these cis-mapping genes than would be expected by chance encode either confirmed or predicted secreted proteins, many of which are known to localize to the specialized secretory organelles characteristic of members of the phylum Apicomplexa. For 6 of the cis-mapping loci we determined if the strain-specific hybridization differences were due to true transcriptional differences or rather strain-specific differences in hybridization efficiency because of extreme polymorphism and/or deletion, and we found examples of both scenarios. Keywords: eQTL mapping; virulence; Toxoplasma gondii 17 F1 progeny from a cross between a type II parent (PDS) and a type III parent (CTG) were used in RNA hybridizations to identify cis and trans-mapping loci regulating gene expression
Project description:Toxoplasma gondii is an intracellular parasite with a significant impact on human health, especially in cases where individuals are immunocompromised (e.g., due to HIV/AIDS). In Europe and North America only a few clonal genotypes appear to be responsible for the vast majority of Toxoplasma infections, and these clonotypes have been intensely studied to identify strain-specific phenotypes that may play a role in the manifestation of more severe disease. To identify and genetically map strain-specific differences in gene expression, we have carried out expression quantitative trait locus (eQTL) analysis on Toxoplasma gene expression phenotypes using spotted cDNA microarrays. This led to the identification of 16 Toxoplasma genes that had significant and mappable strain-specific variation in hybridization intensity. While the analysis should identify both cis and trans-mapping hybridization profiles, we only identified loci with strain-specific hybridization differences that are most likely due to differences in the locus itself (i.e., cis-mapping). Interestingly, a larger number of these cis-mapping genes than would be expected by chance encode either confirmed or predicted secreted proteins, many of which are known to localize to the specialized secretory organelles characteristic of members of the phylum Apicomplexa. For 6 of the cis-mapping loci we determined if the strain-specific hybridization differences were due to true transcriptional differences or rather strain-specific differences in hybridization efficiency because of extreme polymorphism and/or deletion, and we found examples of both scenarios. Keywords: eQTL mapping; virulence; Toxoplasma gondii 19 F1 progeny from a cross between a type II parent (PDS) and a type III parent (CTG) were used in RNA hybridizations to identify cis and trans-mapping loci regulating gene expression
Project description:Two samples, 0hr and 72hr, were used to generate tachyzoite and bradyzoite transcriptional data from tissue-cultured Toxoplasma gondii strain Prugniaud, respectively.
Project description:Two samples, 0hr and 72hr, were used to generate tachyzoite and bradyzoite transcriptional data from tissue-cultured Toxoplasma gondii strain Prugniaud, respectively. Samples are single replicates, and a subset of a larger timeseries. Non-control sample was exposed to alkaline conditions, media pH 8.2, for 72hr.
Project description:Developmental switching in Toxoplasma gondii, from the virulent tachyzoite to the relatively quiescent bradyzoite stage, is responsible for disease propagation and reactivation. We have generated tachyzoite to bradyzoite differentiation (Tbd-) mutants in T. gondii and used these in combination with a cDNA microarray to identify developmental pathways in bradyzoite formation. Four independently generated Tbd- mutants were analysed and had defects in bradyzoite development in response to multiple bradyzoite-inducing conditions, a stable phenotype after in vivo passages and a markedly reduced brain cyst burden in a murine model of chronic infection. Transcriptional profiles of mutant and wild-type parasites, growing under bradyzoite conditions, revealed a hierarchy of developmentally regulated genes, including many bradyzoite-induced genes whose transcripts were reduced in all mutants. A set of non-developmentally regulated genes whose transcripts were less abundant in Tbd- mutants were also identified. These may represent genes that mediate downstream effects and/or whose expression is dependent on the same transcription factors as the bradyzoite-induced set. Using these data, we have generated a model of transcription regulation during bradyzoite development in T. gondii. Our approach shows the utility of this system as a model to study developmental biology in single-celled eukaryotes including protozoa and fungi.