Conserved centrosomal proteins co-localize with TgCentrin1 in tachyzoites.

<p>(A) Schematic representation of the <i>T</i>. <i>gondii</i> tachyzoite centrosome cycle. Centrosome duplication occurs at the G1/S transition, and at the completion of mitosis and budding (M/C) each new daughter parasite inherits a single TgCentrin1-containing centrosome, indicated by red dot. (B) A transgenic strain expressing epitope-tagged TgSas-6^HA and TgCentrin1^myc produced by sequential genetic knock-in shows tight co-localization of these centrosome proteins. A single TgSas-6^HA/TgCentrin1^myc structure in G1 phase duplicated in parasites that had entered S phase. Cell cycle phases of individual parasites and vacuoles were determined based on well-established nuclear and cell morphological criteria [<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002093#pbio.1002093.ref004" target="_blank">4</a>]. (C and D) Using a similar knock-in strategy, <i>T</i>. <i>gondii</i> orthologs of Sfi1 and γ-Tubulin were epitope-tagged with 3xmyc in the genomic locus. Localization of these proteins in the centrosome was established by co-staining the γ-Tubulin^myc transgenic strain with anti-Centrin antibody, and in the TgSfi1^myc transgenic clone, epitope-tagging of TgCentrin1 with 3xHA by genetic knock-in was used. DAPI co-staining (blue) was used to visualize nucleus. Magnified inset images inside the merged images highlight the tight co-localization of the each pair of centrosomal factors in a defined centrosome core structure.