Comments on the Role of the Cyst in the Life Cycle and Survival of Free-Living Protozoa

Corliss, John O.; Esser, Stephen C.

doi:10.2307/3225158

Cited by 177 publications

(101 citation statements)

References 74 publications

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“…1c) occurs in a short, sudden burst induced by appropriate environmental conditions. The addition of water, without wheat material, did not stimulate ciliate production (Fig 1c); hence, ciliate excystment is probably triggered by some substance produced by growing bacteria, e.g., carbon dioxide or an organic bacterial waste product (2,9,13,37,40).…”

Section: Discussionmentioning

confidence: 99%

Population Dynamics of Active and Total Ciliate Populations in Arable Soil Amended with Wheat

Frederiksen

Rønn

2002

Appl Environ Microbiol

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Soil protozoa are characterized by their ability to produce cysts, which allows them to survive unfavorable conditions (e.g., desiccation) for extended periods. Under favorable conditions, they may rapidly excyst and begin feeding, but even under optimal conditions, a large proportion of the population may be encysted. The factors governing the dynamics of active and encysted cells in the soil are not well understood. Our objective was to determine the dynamics of active and encysted populations of ciliates during the decomposition of freshly added organic material. We monitored, in soil microcosms, the active and total populations of ciliates, their potential prey (bacteria and small protozoa), their potential competitors (amoebae, flagellates, and nematodes), and their potential predators (nematodes). We sampled with short time intervals (2 to 6 days) and generated a data set, suitable for mathematical modeling. Following the addition of fresh organic material, bacterial numbers increased more than 1,400-fold. There was a temporary increase in the number of active ciliates, followed by a rapid decline, although the size of the bacterial prey populations remained high. During this initial burst of ciliate growth, the population of cystic ciliates increased 100-fold. We suggest that internal population regulation is the major factor governing ciliate encystment and that the rate of encystment depends on ciliate density. This model provides a quantitative explanation of ciliatostasis and can explain why protozoan growth in soil is less than that in aquatic systems. Internally governed encystment may be an essential adaptation to an unpredictable environment in which individual protozoa cannot predict when the soil will dry out and will survive desiccation only if they have encysted in time.

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Section: Discussionmentioning

confidence: 99%

Population Dynamics of Active and Total Ciliate Populations in Arable Soil Amended with Wheat

Frederiksen

Rønn

2002

Appl Environ Microbiol

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“…1a, closed circles). 'Starvation' is known to be a common factor in encystment induction among a number of protozoans [13]. Starvation-mediated encystment may be involved in the consumption of intracellular encystment-suppressing nutrient molecules and their metabolic products [12].…”

Section: Resultsmentioning

confidence: 99%

Culture Age, Intracellular Ca2+ Concentration, and Protein Phosphorylation in Encystment-Induced Colpoda cucullus

Sogame

Matsuoka

2012

Indian J Microbiol

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In Colpoda cucullus, intracellular Ca 2? mediates the encystment induction and protein phosphorylation that occur just prior to morphogenetic transformation into the resting form. When rapidly growing cells were stimulated to encyst, encystment was not readily induced, and the protein phosphorylation level was lower. On the other hand, in post-growing cells stimulated to encyst, the encystment rate and protein phosphorylation level were elevated. These results suggest that protein phosphorylation is closely linked to encystment induction. Why, then, are the protein phosphorylation level and encystment rate difficult to elevate in the rapidly growing cells? Fura 2 ratiometry showed that the intracellular Ca 2? concentration (F 340 /F 380 ratio) was raised in rapidly growing cells as well as in post-growing cells when the cells were stimulated to encyst. It is presumed that the Ca 2? -mediated signal transduction pathways for protein phosphorylation and encystment may be triggered in rapidly growing cells, but downstream certain steps may be suppressed by certain intracellular components.

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“…Cyst formation by free-living protozoa, including planktonic forms, is well known as a common strategy in thelr life cycle (Corliss & Esser 1974). Especially in the case of neritic temperate and boreal plankton, a resting stage is the primary strategy for survival in a seasonally variable environment (Smayda 1958).…”

Section: Introductionmentioning

confidence: 99%

Excystment of the oligotrich ciliate Strombidium conicum

Kim¹,

Taniguchi²

1995

Aquat. Microb. Ecol.

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Cysts of an oligotrich ciliate were isolated from sediment samples collected in Onagawa Bay on the northeastern Pacific coast of Japan and incubated under laboratory culture conditions. Successful excystment occurred regularly and the excysted cells Tvere identified as Strombidium conicum. The cyst of S. conicum has a papuliferes form and is enveloped by a double-layered wall, rigid inner and membranous outer layers. The excysted cells showed a distinctive conical shape with welldeveloped trichltes and a ventral kinety restricted to the posterior e n d . The effects on excystment of temperature, light intensity, oxygen concentration, bacteria, a n d storage in the dark and at cold temperatures a r e reported. Among these variables, temperature is likely to b e the principal factor controlling excystment.

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Comments on the Role of the Cyst in the Life Cycle and Survival of Free-Living Protozoa

Cited by 177 publications

References 74 publications

Population Dynamics of Active and Total Ciliate Populations in Arable Soil Amended with Wheat

Population Dynamics of Active and Total Ciliate Populations in Arable Soil Amended with Wheat

Culture Age, Intracellular Ca2+ Concentration, and Protein Phosphorylation in Encystment-Induced Colpoda cucullus

Excystment of the oligotrich ciliate Strombidium conicum

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