Resting cysts: A survival strategy in Protozoa Ciliophora

Abstract

Encystment is a reversible cell differentiation process that also requires an antagonistic process, i.e. excystment. Both processes are genetically encoded. Encystment is of common occurrence among free-living ciliates and may serve several different purposes. In some ciliates, this process is part of the regular life cycle (reproductive cyst), while many other ciliates undergo encystment when environmental conditions become adverse (resting cyst). In this review, the different phases and aspects of the encystment process in ciliates, such as the ecological role, the cyst formation, the morphological characteristics of the cysts and their dynamic state during the time and the excysting process are reviewed on the basis on our own results and literature data.

Seasonal and Interannual Changes in Ciliate and Dinoflagellate Species Assemblages in the Arctic Ocean (Amundsen Gulf, Beaufort Sea, Canada)

“…Earlier microscopy (Lovejoy et al, 1993;Okolodkov and Dodgeb, 1996;Jiang et al, 2013) and clone library studies using longer 18S rRNA sequences (Bachy et al, 2011;Lovejoy and Potvin, 2011) have also highlighted the differences between SCM and surface communities over the Arctic. Within the two water masses, communities separated by template suggests a pool of historic DNA, which could include dormant or less active stages, e.g., cysts (Verni and Rosati, 2011;Bravo and Figueroa, 2014), advected non-active species (Lovejoy and Potvin, 2011), preserved free DNA, or non-living material in marine snow (Nielsen et al, 2007;Boere et al, 2011). All of these sources can be transported by currents and persist over long distances (Heiskanen, 1993;Brocks and Banfield, 2009).…”

Morphological and molecular characterization of Parafurgasonia zhangi spec. nov. and Chilodonella acuta Kahl, 1931 (Protozoa, Ciliophora), from a soil habitat of Saudi Arabia

“…They play an important role in nutrient cycling of terrestrial food webs (Acosta-Mercado & Lynn, 2004;Chao et al, 2006). With the ability to form resistant resting cysts, soil ciliates are adapted well to various soil habitats even including desert sand dunes (Foissner et al, 2002(Foissner et al, , 2008Verni & Rosati, 2011). Compared with the large number of investigations on marine ciliate fauna of the Saudi Arabian coasts (AlRasheid, 1996(AlRasheid, , 1997(AlRasheid, , 1999(AlRasheid, , 2001Al-Farraj, 2008;Chen et al, 2013), ciliates from soil habitats of Saudi Arabia remain poorly known.…”

A Study on Resting Cysts of an Oxytrichid Soil Ciliate, Rigidohymena quadrinucleata (Dragesco and Njine, 1971) Berger, 2011 (Ciliophora, Hypotrichia), Including Notes on its Encystation and Excystation Process

“…On the basis of literature references (Beers 1945(Beers , 1948(Beers , 1966Repak 1968;Foissner 1993;Verni and Rosati 2011;Vďačný and Foissner 2012;Funadani et al 2013;Benčaťová et al 2016;Benčaťová and Tirjaková 2017) we recognised two basic types of emergence of motile specimens during the excystation process: (i) escape throught a special escape apparatus -emergence pore/operculum with a removable "plug"; and (ii) escape throuth a rupture of a cyst wall by pressure of moving cell and excystation vacuole.…”