Distinct strains of Toxoplasma gondii feature divergent transcriptomes regardless of developmental stage

PLoS One. 2014 Nov 13;9(11):e111297. doi: 10.1371/journal.pone.0111297. eCollection 2014.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Cell Cycle Checkpoints / genetics
  • Cell Differentiation / genetics
  • Gene Expression Profiling
  • High-Throughput Nucleotide Sequencing
  • Hydrogen-Ion Concentration
  • Life Cycle Stages / genetics*
  • Protozoan Proteins / genetics*
  • RNA, Messenger / genetics
  • Sequence Analysis, DNA
  • Toxoplasma / classification
  • Toxoplasma / genetics*
  • Toxoplasma / growth & development
  • Transcription Factor AP-2 / genetics*
  • Transcriptome / genetics*


  • Protozoan Proteins
  • RNA, Messenger
  • Transcription Factor AP-2

Associated data

  • GEO/GSE60305