Parasite lacking SFA go through mitosis normally but fail to form daughter cells.

<p>(A) iΔSFA2 parasites grown in the presence or absence of ATc for 24 h were labeled with anti-IMC1 (green) and DAPI (blue) anti-centrin (red, centrosomes, upper panels) or anti-CenH3 (red, centromeres, lower panels). Representative examples are shown for cells in interphase or division. Interphase nuclei associate with a single centrosome, while larger 2N nuclei associate with two. This is unchanged by ATc treatment. Interphase nuclei contain a haploid genome and exhibit one CenH3 dot representing a cluster of the centromeres of all 14 chromosomes bundled in the nucleus in close proximity to the centrosome (see <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001444#pbio.1001444-Brooks1" target="_blank">[9]</a>). Dividing nuclei exhibit two CenH3 dots representing duplicated chromosomes. Again, this labeling pattern is not affected in the mutant when judged on a per nucleus basis. Note though that in both cases the ATc-treated cell is already tetraploid with no sign of cytokinesis. (B) The number of CenH3 dots per nucleus was quantified in IFA experiments for untreated or ATc-treated iΔSFA2 parasites. The number of CenH3 dots, representing the number of chromosome sets per nucleus, is graphed, error bars show standard deviation (>50 parasite vacuole per experiment counted, <i>n</i> = 3). (C) Immunofluorescence of iΔSFA2 parasites after 48 h ATc treatment showing IMC1 (green), DAPI (blue), and anti-ISP1 (red). ISP1 labels the apical cap of the IMC of both mother and daughter cells and is an early marker of budding <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001444#pbio.1001444-Beck1" target="_blank">[27]</a>. ISP1 staining for daughter cells is absent in the ATc-treated mutant. Note that the nuclei have completed mitosis in these cells and compare to a similar stage shown for untreated parasite.