How Ciliated Protists Survive by Cysts: Some Key Points During Encystment and Excystment

Li, Yuqing; Wang, Yurui; Zhang, Shijing; Maurer‐Alcalá, Xyrus X.; Yan, Ying

doi:10.3389/fmicb.2022.785502

Cited by 13 publications

(16 citation statements)

References 111 publications

(215 reference statements)

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“…2003; Javaux & Lepot 2017; Agić & Cohen 2021) given that they require not only elaborate morphostructure but also tightly controlled enzymatic activity to release the operculum while leaving the rest of the vesicle unaffected (Chambers & Thompson 1972; Li et al . 2022). Operculate structures are not known from prokaryotes, but do occur broadly across modern protistan groups (e.g.…”

Section: Discussionmentioning

confidence: 99%

Early eukaryotic microfossils of the late Palaeoproterozoic Limbunya Group, Birrindudu Basin, northern Australia

Riedman,

Porter,

Lechte

et al. 2023

Papers in Palaeontology

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Fine‐grained, siliciclastic units of the >1642 ± 3.9 Ma late Palaeoproterozoic Limbunya Group, Birrindudu Basin host rich, well‐preserved organic‐walled microfossil assemblages that include members of total‐group eukaryotes. These assemblages include taxa characteristic of this interval such as Tappania plana and Satka favosa, as well as less common taxa such as Gigantosphaeridium fibratum, Gigantosphaeridium floccosum, Kamolineata elongata (= Valeria elongata; new combination), and four new species. The new taxa include Limbunyasphaera operculata gen et sp. nov., the oldest known operculate taxon; the large septate filaments of Siphonoseptum bombycinum gen. et sp. nov.; the platy tubular form Birrindudutuba brigandinia gen. et sp. nov.; and Filinexum torsivum gen. et sp. nov., which bears a spirally twisted wall constructed of bound fibres. Our data show that eukaryotic fossils are particularly abundant in marginal marine environments such as tidal flats and back‐barrier lagoonal settings. This is exemplified by the Blue Hole Formation, which features an especially diverse and complex assemblage. We also present a new within‐formation eukaryotic species richness estimate for the Palaeoproterozoic to Tonian. This estimate indicates that the oldest eukaryote‐bearing units already show species richness levels similar to those of the much younger and more heavily sampled Tonian period. Additionally, these oldest eukaryotic assemblages show significant morphological disparity, particularly in vesicle construction. These high levels of eukaryotic species richness and morphological disparity suggest that although late Palaeoproterozoic units preserve our oldest record of eukaryotes, the eukaryotic clade has a much deeper history.

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Section: Discussionmentioning

confidence: 99%

Early eukaryotic microfossils of the late Palaeoproterozoic Limbunya Group, Birrindudu Basin, northern Australia

Riedman,

Porter,

Lechte

et al. 2023

Papers in Palaeontology

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“…The previous study showed that autophagic vacuoles in stage C might digest the organelles and other structures for supplying energy and materials for biosynthetic to maintain life activities and provide the condition for cyst (Li et al, 2022). Our study revealed oxidative phosphorylation and starch and sucrose metabolism were significantly enriched in stage C compared to stage G of A .…”

Section: Discussionmentioning

confidence: 99%

“…In recent decades, research studies on ciliate cysts mainly focused on physiological diversity and morphological structure by ultrastructural analysis (Gutiérrez et al, 2001; Kida & Matsuoka, 2006; Verni & Rosati, 2011). It was reported that the process of encystment including structural changes and the morphology of cysts varied among ciliate species (Corliss & Esser, 1974; Li et al, 2022; Van Wagtendonk, 1955). A few studies have suggested that ciliate cyst formation was a complex process regulated jointly by signaling pathways and reported some genes related to this process, including ubiquitin, Ca 2+ ‐ATPase, actin, and MAPK‐related kinase (Gao et al, 2015; Grisvard et al, 2008; Jiang et al, 2019; Pan et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Novel insights into molecular mechanisms of vegetative cell cycle and resting cyst formation in Apodileptus cf. visscheri (Alveolata, Ciliophora)

Shen²,

et al. 2022

J Eukaryotic Microbiology

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Ciliates usually with big cell sizes, complex morphological structures, and diverse life cycles, are good model organisms for studying cell proliferation regulation of eukaryotes. Up to date, the molecular regulation mechanisms for the vegetative cell cycle and encystment of these ciliates are poorly understood. Here, transcriptomes of Apodileptus cf. visscheri, which has an asexual vegetative cell cycle and is apt to encyst when environmental conditions become unfavorable, were sequenced to enrich our related knowledge. In this study, three replicates were sequenced for each of four cell stages, including initial period of growth, morphogenesis, cell division, and resting cyst. The significant transcription differences, involving cell cycle, biosynthesis, and energy metabolism pathways, were revealed between the resting cyst and vegetative cell cycle. Further investigations showed that the cell cycle pathway was enriched during morphogenesis stage and cell division stage. Compared to the initial period of growth stage, the differentially expressed genes involved in cellular components and molecular function were significantly enriched during cell division stage, while cellular components and biological processes were significantly enriched during morphogenesis stage. These provide novel insights into a comprehensive understanding at the molecular level of the survival and adaptive mechanism of unicellular eukaryotes.

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“…Encysting species can sustain relatively high mortality rates because those refer to trophonts (i.e., motile cells) only (Weisse et al 2023b). Encysted specimens may survive starvation and other unfavorable conditions for a long time (Verni and Rosati 2011;Li et al 2022). Therefore, relatively high mortality rates of the trophonts of cyst-forming ciliates may reduce the species' fitness only moderately.…”

Section: Physiological Mortality Vs Predator-induced Mortalitymentioning

confidence: 99%

Physiological mortality of planktonic ciliates: Estimates, causes, and consequences

Weisse

2024

Limnology & Oceanography

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Contrasting physiological mortality with predator‐induced mortality is of tremendous importance for the population dynamics of many organisms but is difficult to assess. This is especially true for tiny organisms, such as most protists, which do not leave any carcasses behind. I performed a meta‐analysis using planktonic ciliates as model organisms to estimate the maximum physiological mortality rates (δmax) across pelagic ecosystems in relation to environmental and biotic factors. The median δmax of planktonic ciliates was 0.62 d−1 and did not differ between marine and freshwater species. Maximum ciliate mortality rates were species‐specific and affected by their specific growth rates (rmax), cell volume, and ability to encyst. Cyst‐forming species had, on average, higher δmax than species unable to encyst. Maximum mortality rates were positively related to rmax, but, in contrast to the latter, δmax appeared unaffected by temperature. I conclude that (1) in the ocean, physiological mortality is more critical for controlling ciliate population size than ciliate losses imposed by microcrustacean predation, but (2) in many lakes, the opposite holds; (3) cyst formation is an effective ciliate trait to cope with the high mortality of motile cells upon starvation. The lack of a temperature effect on δmax deserves further study; if correct, planktonic ciliates may take advantage of rising ocean and lake temperatures, with important implications for the pelagic food web.

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How Ciliated Protists Survive by Cysts: Some Key Points During Encystment and Excystment

Cited by 13 publications

References 111 publications

Early eukaryotic microfossils of the late Palaeoproterozoic Limbunya Group, Birrindudu Basin, northern Australia

Early eukaryotic microfossils of the late Palaeoproterozoic Limbunya Group, Birrindudu Basin, northern Australia

Novel insights into molecular mechanisms of vegetative cell cycle and resting cyst formation in Apodileptus cf. visscheri (Alveolata, Ciliophora)

Physiological mortality of planktonic ciliates: Estimates, causes, and consequences

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