Molecular genetics of regulated secretion in Paramecium

Vayssié, Laurence; Skouri, Fériel; Sperling, Linda; Cohen, Jean

doi:10.1016/s0300-9084(00)00201-7

Cited by 70 publications

(91 citation statements)

References 126 publications

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“…Theoretically a primary effect of interfering with Ca 2ϩ homeostasis by CRC-II-1 silencing could be the requirement of a Ca 2ϩ -activated calreticulin complex for correct processing and folding of secretory proteins (20,38). Although a calreticulinlike protein occurs in Paramecium (73), we see in Western blots, after CRC-II-1 silencing, a correctly cleaved TMP4 protein comparable to the size of processed TMPs in normal cells (31,99). The small number of trichocysts, mostly remaining unattached inside the cytoplasm, observed after CRC-II-1 silencing may largely represent residual organelles persisting from before gene silencing.…”

Section: Discussionmentioning

confidence: 93%

“…A salient aspect concerning reduced trichocyst numbers after CRC-II-1 silencing may concern budding of precursor vesicles and their transport and fusion, as this also occurs during trichocyst biogenesis (99). In higher eukaryotic cells, some of these processes, or steps thereof, are known to be subject to Ca 2ϩ regulation (1,6).…”

Section: Discussionmentioning

confidence: 99%

“…Besides [Ca 2ϩ ] homeostasis, the Paramecium cell has to regulate a variety of well-characterized processes (75). This includes exocytosis of dense-core secretory vesicles (trichocysts) (71,74,99). Each cell possesses up to 1,000 trichocysts attached to the cell membrane.…”

Section: Camentioning

confidence: 99%

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Novel Types of Ca²⁺ Release Channels Participate in the Secretory Cycle of Paramecium Cells

Ladenburger¹,

Sehring²,

Korn³

et al. 2009

Molecular and Cellular Biology

121

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A database search of the Paramecium genome reveals 34 genes related to Ca 2؉ -release channels of the inositol-1,4,5-trisphosphate (IP 3 ) or ryanodine receptor type (IP 3 R, RyR). Phylogenetic analyses show that these Ca 2؉ release channels (CRCs) can be subdivided into six groups (Paramecium tetraurelia CRC-I to CRC-VI), each one with features in part reminiscent of IP 3 Rs and RyRs. We characterize here the P. tetraurelia CRC-IV-1 gene family, whose relationship to IP 3 Rs and RyRs is restricted to their C-terminal channel domain. CRC-IV-1 channels localize to cortical Ca 2؉ stores (alveolar sacs) and also to the endoplasmic reticulum. This is in contrast to a recently described true IP 3 channel, a group II member (P. tetraurelia IP 3 R N -1), found associated with the contractile vacuole system. Silencing of either one of these CRCs results in reduced exocytosis of dense core vesicles (trichocysts), although for different reasons. Knockdown of P. tetraurelia IP 3 R N affects trichocyst biogenesis, while CRC-IV-1 channels are involved in signal transduction since silenced cells show an impaired release of Ca 2؉ from cortical stores in response to exocytotic stimuli. Our discovery of a range of CRCs in Paramecium indicates that protozoans already have evolved multiple ways for the use of Ca 2؉ as signaling molecule.Ca 2ϩ is an important component of cell activity in all organisms, from protozoa to mammals. Thereby Ca 2ϩ may originate from the outside medium and/or from internal stores (7, 18). Ca 2ϩ release from internal stores is mediated by various Ca 2ϩ release channels (CRCs), of which the inositol-1,4,5-trisphosphate receptor (IP 3 R) and ryanodine receptor (RyR) families have been studied most extensively (8,9,29,63 (14). IP 3 generates and maintains a Ca 2ϩ gradient in the hyphal tip of Neurospora crassa and the IP 3 -sensitive channels have been reconstituted and characterized with the planar bilayer method (87). In summary, these publications suggest that IP 3 -dependent signaling pathways are conserved among unicellular organisms, including protozoa.Despite these data, the molecular characterization of IP 3 or ryanodine receptors in low eukaryotes is currently a challenge since the identification of orthologues has not been possible thus far, probably because of evolutionary sequence divergence (66). Traynor et al. (96) identified an IP 3 receptor-like protein, IplA, in Dictyostelium discoideum, which possesses regions related to IP 3 R sequences, but thus far no evidence for IP 3 interaction exists. We have recently described an IP 3 R in the ciliated protozoa Paramecium tetraurelia (referred to here as P. tetraurelia IP 3 R N ) (53), with features characteristic of mammalian IP 3 Rs in terms of topology and ability for IP 3 binding. The expression level of P. tetraurelia IP 3 R N is modulated by extracellular Ca 2ϩ concentrations ([Ca 2ϩ ] o ) and immunofluorescence studies reveal an unexpected localization to the contractile vacuole complex (CVC), the major organelle involved in osmoregulation...

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Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

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Novel Types of Ca²⁺ Release Channels Participate in the Secretory Cycle of Paramecium Cells

Ladenburger¹,

Sehring²,

Korn³

et al. 2009

Molecular and Cellular Biology

121

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“…It belongs to the Ciliate phylum (Ciliophora). The use of Paramecium species as a model of survey has been reported by several authors in some disciplines; in ecotoxicology, Paramecium species were used to study environmental qualities and toxic effects of industrial, agricultural and domestic chemicals (Edmiston et al, 1985;Madoni, 2000;Miyoshi et al, 2003;Takahashi et al, 2005;Venkateswara et al, 2006;Rouabhi et al, 2006;Mortuza et al, 2009Mortuza et al, , 2010Amanchi, 2010); in genetic, because its sequencing genome is well known, researchers used P. tetraurelia for genetic analysis, gene expression and mutation (Houten et al, 1977;Brygoo, 1977;Mayer et al, 1998;Haynes et al, 2000;Vayssié et al, 2000). In physiology, paramecia are used in general for studying the role, the function and the cell organization.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Paramecium tetraurelia growth kinetics and its sensitivity to combined effects of azoxystrobin and cyproconazole

Zoubir¹,

Berrebbah²,

Reda³

2011

Afr. J. Microbiol. Res.

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For using an organism for ecotoxicological studies, it is important to understand its model of growth under some physicochemical parameters that influence with a direct manner its development. The knowledge of the optimal parameters for the paramecia development leads to realize a model of growth with clear stages. For that, we tried to study the influence of temperature, pH, nutrient density in the culture medium and pollution on the growth of Paramecium tetraurelia. Obtained results showed that paramecia prefer definite conditions. However, the growth was better in temperatures included between 25 and 30°C, with preference to increased temperatures and a slightly acidic pH. The culture medium was prepared from the mixture of several vegetables which the rates were studied depending to the growth. The combined effects of azoxystrobin and cyproconazole on the growth kinetics were studied. Results showed that treatment affected the population growth, the generation time and the velocity of generation.

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“…These studies made important discoveries such as microbial sexuality and the occurrence of mating types 1 , surface antigens 2 , cytoplasmic inheritance 3 and an epigenetic phenomenon not mediated by DNA, called structural heredity 4 . More recently, Paramecium has become a powerful model unicell in various fields including membrane excitability 5 and signal transduction 6,7 , regulated secretion 8 , cellular morphogenesis 9,10 , surface antigen variation 11 , developmental genome rearrangements 12,13 , and homology-dependent epigenetic regulation of both gene expression 14 and developmental genome rearrangements 15 . The recent availability of DNA-mediated transformation 16 allowed complementation cloning of genes identified by mutation [17][18][19] and gene inactivation by homology-dependent gene silencing through a mechanism related to RNA interference 14,20 .…”

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confidence: 99%

Paramecium genome survey: a pilot project

et al. 2001

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Molecular genetics of regulated secretion in Paramecium

Cited by 70 publications

References 126 publications

Novel Types of Ca²⁺ Release Channels Participate in the Secretory Cycle of Paramecium Cells

Novel Types of Ca²⁺ Release Channels Participate in the Secretory Cycle of Paramecium Cells

Optimization of Paramecium tetraurelia growth kinetics and its sensitivity to combined effects of azoxystrobin and cyproconazole

Paramecium genome survey: a pilot project

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Molecular genetics of regulated secretion in Paramecium

Cited by 70 publications

References 126 publications

Novel Types of Ca2+ Release Channels Participate in the Secretory Cycle of Paramecium Cells

Novel Types of Ca2+ Release Channels Participate in the Secretory Cycle of Paramecium Cells

Optimization of Paramecium tetraurelia growth kinetics and its sensitivity to combined effects of azoxystrobin and cyproconazole

Paramecium genome survey: a pilot project

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Novel Types of Ca²⁺ Release Channels Participate in the Secretory Cycle of Paramecium Cells

Novel Types of Ca²⁺ Release Channels Participate in the Secretory Cycle of Paramecium Cells