1887

Abstract

trophozoites differentiate into infectious cysts (encystment) in response to physiological stimuli; encystment is crucial for ’s transmission, survival and pathogenesis. , encysts when bile sequesters lipids necessary for this lipid auxotroph, and they encyst to infect new hosts. In this study, we investigated, for the first time, commitment to encystment in using both molecular and cellular techniques. We show that after 3–6 h in inducing conditions, encysting trophozoites continue to encyst regardless of whether the inducing stimulus remains. We propose that a trophozoite’s inability to revert to a growing or dividing trophozoite represents a commitment to encystment. The onset of commitment correlated with the appearance of encystment specific vesicles (ESVs) and encystment specific protein synthesis. These observations suggest the involvement of regulatory pathways with the ability to ‘remember’ a transient signal long after its removal; a property that enables encysting trophozoites to complete the encystment process should the unfavourable triggering condition(s) change. The ability to form cysts in response to transient signals or, as we have highlighted in this paper, the ability of a small percentage of the population to form cysts without an inducer is vital for the maintenance of infection within populations.

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2014-02-01
2020-10-31
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