Table 1.

Morphological events occurring during replication of T. gondii parasite tachyzoites

Time count (hours:minutes) Events Images
0 to 1:15 G1 phase (may vary in length up to 4 hours)*
Centriole, Golgi and apicoplast closely associated at the apical end of the nucleus Fig. 2A-C
1:15 to 1:45 First morphological changes
Centriole migrates away from the apical end Fig. 2F and Fig. 7 (magenta, increasing)
Golgi elongates Fig. 2D and Fig. 7 (yellow, increasing)
Apicoplast migrates to juxtanuclear region, associates with mitochondrion, and elongates§ Fig. 2E-F, Fig. 5B-C and Fig. 7 (green, increasing)
1:45 to 3:0 Initial stages of mitotic division
Centriole divides Fig. 2I and Fig. 7 (magenta, peak)
Golgi divides Fig. 2G and Fig. 7 (yellow, peak)
Initiation of DNA replication Fig. 7 (turquoise, increasing)
Apicoplast continues to elongate§ Fig. 2H-I and Fig. 7 (green, increasing)
Centriole returns to the apical end and associates with apicoplast Fig. 2L and Fig. 7 (magenta, decreasing)
3:0 to 3:30 Establishment of the daughter cytoskeleton
Daughter conoids form** Fig. 7 (purple, increasing)
Spindle poles and intranuclear spindle form** Fig. 7 (purple, increasing)
1.8N DNA content Fig. 7 (turquoise)
Inner membrane complex assembly begins†† Fig. 2J-K, Figs 3, 4, Fig. 5A and Fig. 7 (purple)
Apical ruffling of endoplasmic reticulum‡‡ Figs 3 and 7 (brown, increasing)
3:30 to 4:30 Organellar partitioning (early stages)
Daughter inner membrane complexes elongate†† Fig. 2M-N, Figs 3, 4, Fig. 5A and Fig. 7 (purple)
Apicoplast partitioned and divides§ Fig. 2N-O and Fig. 7 (green)
Nucleus partitioned and divides§§ Fig. 2N-O and Fig. 7 (blue)
ER partitioned between daughters‡‡ Figs 3 and 7 (brown)
Initiation of de novo rhoptry and microneme biogenesis¶¶ Figs 4 and 7 (orange, increasing)
Mitochondrion forms branches Fig. 5A and Fig. 7 (red, increasing)
4:30 to 6:30 Organellar partitioning (late stages)
Continued partitioning of ER‡‡ Figs 3 and 7 (brown, decreasing)
Continued rhoptry and microneme biogenesis¶¶ Figs 4 and 7 (orange, increasing)
Daughter inner membrane complexes complete†† Figs 3, 4, Fig. 5A and Fig. 7 (purple)
Mitochondrion enters daughter scaffolds Fig. 5A and Fig. 7 (red, decreasing)
6:30 Emergence of daughter parasites
Daughter parasites bud from mother, picking up plasma membrane‡‡ Fig. 3 and Fig. 5A
Residual material left behind (including waste, ER, mitochondrion, plasma membrane etc.)‡‡ Fig. 3, Fig. 5A and Fig. 6
  • * (Fichera et al., 1995; Radke and White, 1998; Radke et al., 2001; Hu et al., 2002; Hu et al., 2004)

  • (Sheffield and Melton, 1968; Bannister et al., 2000a; Striepen et al., 2000; Ferguson et al., 2005; Hartmann et al., 2006)

  • (Hartmann et al., 2006; Pelletier et al., 2002)

  • § (Striepen et al., 2000)

  • (Radke et al., 2001; Hu et al., 2002; Hu et al., 2004)

  • ** (Hu et al., 2006)

  • †† (Hu et al., 2002; Mann and Beckers, 2001)

  • ‡‡ (Hager et al., 1999)

  • §§ (Hu et al., 2002)

  • ¶¶ (Carruthers and Sibley, 1997)