Application of metabolomic analysis to the
understanding of encystation (stage
conversion)
Stage conversion is often accompanied by most drastic
biochemical and morphological changes. The transition
from the motile proliferating disease-causing trophozoites
to the dormant cyst form, named encystation, is essential
for parasite survival in the environment and transmission.
Jeelani et al. recently investigated metabolic and transcriptomic
changes that occur during encystation in E.
invadens, which is a relative of E. histolytica from reptiles,
and, unlike E. histolytica, encysts in in vitro culture, usingcapillary electrophoresis/time-of-flight massspectrometry
(CE-ToFMS) and DNA microarray analysis [35]. It was
demonstrated that as encystation progresses, the levels of
a majority of metabolites involved in glycolysis as well as
all nucleotides decreased markedly. Furthermore, intermediates
for chitin biosynthesis dramatically increased
(Figure 1). These findings agree very well with the notion
created by numerous previous works: energy generation
and storage ceases during and after encystation, and the
flux of glucose utilization shifts from glycolysis and fermentation
to chitin wall biosynthesis.