Distinct strains of Toxoplasma gondii feature divergent transcriptomes regardless of developmental stage.
Using high through-put RNA sequencing, we assayed the transcriptomes of three different strains of Toxoplasma gondii representing three common genotypes under both in vitro tachyzoite and in vitro bradyzoite-inducing alkaline stress culture conditions. Strikingly, the differences in transcriptional profiles between the strains, RH, PLK, and CTG, is much greater than differences between tachyzoites and alkaline stressed in vitro bradyzoites. With an FDR of 10%, we identified 241 genes differentially expressed between CTG tachyzoites and in vitro bradyzoites, including 5 putative AP2 transcription factors. We also observed a close association between cell cycle regulated genes and differentiation. By Gene Set Enrichment Analysis (GSEA), there are a number of KEGG pathways associated with the in vitro bradyzoite transcriptomes of PLK and CTG, including pyrimidine metabolism and DNA replication. These functions are likely associated with cell-cycle arrest. When comparing mRNA levels between strains, we identified 1,526 genes that were differentially expressed regardless of culture-condition as well as 846 differentially expressed only in bradyzoites and 542 differentially expressed only in tachyzoites between at least two strains. Using GSEA, we identified that ribosomal proteins were expressed at significantly higher levels in the CTG strain than in either the RH or PLK strains. This association holds true regardless of life cycle stage.
Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America.
Matthew McKnight
MM
Croken
Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, United States of America.
Yanfen
Y
Ma
Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington, United States of America.
Lye Meng
LM
Markillie
Computational Biology and Bioinformatics Group, Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America.
Ronald C
RC
Taylor
Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington, United States of America.
Galya
G
Orr
Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, United States of America; Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, United States of America.
Louis M
LM
Weiss
Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America; Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, United States of America; Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, United States of America.
Kami
K
Kim
D001483:Base Sequence; D059447:Cell Cycle Checkpoints / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D020869:Gene Expression Profiling; D059014:High-Throughput Nucleotide Sequencing; D006863:Hydrogen-Ion Concentration; D008018:Life Cycle Stages / Q000235:genetics*; D015800:Protozoan Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D017422:Sequence Analysis, DNA; D014122:Toxoplasma / Q000145:classification / Q000235:genetics* / Q000254:growth & development; D050656:Transcription Factor AP-2 / Q000235:genetics*; D059467:Transcriptome / Q000235:genetics*
D015800:Protozoan Proteins; D012333:RNA, Messenger; D050656:Transcription Factor AP-2