1. Evidence for active endodyogeny within purified tissue cysts.
Evidence for active endodyogeny within purified tissue cysts. (A) Schematic depiction of endodyogeny, revealing the formation of daughter buds visualized by intense TgIMC3 labeling. The newly formed daughter buds extend within the mother, exhibiting high TgIMC3 intensity as nuclear division results in a bilobe nucleus. Finally, upon the completion of endodyogeny, two new parasites emerge following the degradation and recycling of maternal components. (B) Detection of daughter buds in multiple parasites within a cyst detected with anti-TgIMC3 antibody. One of many such examples is highlighted in the yellow box within the DIC and deconvoluted (Decon) image and magnified to reveal both the TgIMC3 and DNA signals (yellow box). Note that the parasite has a single enlarged nucleus that has not initiated mitosis. (C) Elongation of the daughter buds reveals the outlines of the two progeny parasites (yellow box), with the nucleus revealing a distinct bilobe shape as it migrates into the forming daughter cells. (D) Multiple instances of later stages on endodyogeny (red and yellow boxes) reveal intense TgIMC3 labeling of parasites still connected to the maternal residual body. Note that mitosis in these parasites has been completed as each daughter has a distinct nucleus (red and yellow asterisks). (E) A high proportion of emerging TgIMC3-positive daughter parasites within a tissue cyst. Two highlighted examples (yellow and red boxes) reveal a characteristic “V” pattern in separating daughters still attached to the residual body seen in both the TgIMC3 and DIC images (yellow box; yellow asterisks mark their nuclei). Also seen are two recently divided parasites adjacent to each other exhibiting intense TgIMC3 labeling (red box). All the tissue cysts depicted here were harvested at week 3 postinfection. Additional examples are shown in Fig. S3 in the supplemental material.
Elizabeth Watts et al. mBio 2015; doi: /mBio