Abstract
Limno-terrestrial tardigrades can withstand
almost complete desiccation through a mechanism called
anhydrobiosis, and several of these species have been
shown to survive the most extreme environments through
exposure to space vacuum. Molecular mechanism for
this tolerance has so far been studied in many
anhydrobiotic metazoans, leading to the identification of
several key molecules such as the accumulation and
vitrification of trehalose as well as the expression of LEA
proteins to prevent protein aggregation. On the other
hand, the understanding of comprehensive molecular
mechanisms and regulation machinery of metabolic
compounds during anhydrobiosis is yet to be explored. In
this review, I report and summarize the recent progress in
the comprehensive metabolome analysis using the
tardigrade Ramazzottius varieornatus, which is a
potential model species for anhydrobiosis. In order to
analyze the metabolic changes in the active and
dehydrated states, metabolome is measured in both
conditions using two types of high-throughput mass
spectrometry (MS) systems, liquid chromatography
time-of-flight MS (LC-TOFMS) for lipids and sugars
and capillary electrophoresis TOFMS (CE-TOFMS) for
primary metabolite. Increase, but no significant
accumulation of trehalose in this species was confirmed,
suggesting a more complex mechanism for
anhydrobiosis in comparison to other metazoans. While
changes in gene expression profiles are limited in
between active and tun states, dynamic changes were
observed in the metabolism of this species in response to
desiccation. Changes in the metabolic profiles suggest
complex intracellular responses to oxidative and osmotic
stress.
