Actin in the ciliated protozoan <i>Climacostomum virens</i>: Purification by DNAse I affinity chromatography, electrophoretic characterization, and immunological analysis

Fahrni, José

doi:10.1002/cm.970220107

Cited by 9 publications

(8 citation statements)

References 71 publications

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“…The gene product encoded by the Tetrahymena actin gene analyzed is reported to possess some aberrant features, such as no DNase! binding (Hirono et al, 1989), whereas Fahrni (1992) could isolate actin of a typical 43 kDa from Climacostomum by using DNaseI affinity chromatography.…”

Section: Actin and Myosinmentioning

confidence: 99%

Calcium in ciliated protozoa: Sources, regulation, and calcium-regulated cell functions

Plattner

Klauke²

2001

International Review of Cytology

105

121

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In ciliates, a variety of processes are regulated by Ca 2 ', e.g., exocytosis, endocytosis, ciliary beat, cell contraction, and nuclear migration. Differential microdomain regulation may occur by activation of specific channels in different cell regions (e.g., voltagedependent Ca 2 ' channels in cilia), by local, nonpropagated activation of subplasmalemmal Ca stores (alveolar sacs), by different sensitivity thresholds, and eventually by interplay with additional second messengers (cilia). During stimulus-secretion coupling, Ca 2 ' as the only known second messenger operates at -5 f.tM, whereby mobilization from alveolar sacs is superimposed by "store-operated Ca

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Section: Actin and Myosinmentioning

confidence: 99%

Calcium in ciliated protozoa: Sources, regulation, and calcium-regulated cell functions

Plattner

Klauke²

2001

International Review of Cytology

105

121

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“…Moreover, when comparisons are made between the different ciliate taxa, actins also exhibit extensive sequence variability [3]. Some ciliate actins also exhibit anomalous biochemical properties, such as the inability to bind phalloidin or DNase I [9, 171, and the lack of a Mg++ requirement for assembly [9].…”

mentioning

confidence: 99%

“…However, one aspect of ciliate motility that clearly appears to be actin-dependent is phagocytosis. Inhibition of phagosome formation by cytochalasin B has been extensively documented in Paramecium [l ,5,9,10,371,Tetrahymena 122,33,34,36,371 and Dileptus [40]. There are also considerable supporting data, from phalloidin labeling, from immunocytochemistry and from heavy meromyosin (HMM) decoration studies, that actin is present in the oral apparatus of several diverse ciliates, including Pseudomicrothorax [ it would be expected to play a role in phagosome formation andor movement.…”

mentioning

confidence: 99%

Relative Potencies of Different Cytochalasins for the Inhibition of Phagocytosis in Ciliates

Zackroff

Hufnagel

1998

J Eukaryotic Microbiology

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Ciliate actins have been reported to exhibit an unusual degree of sequence divergence, within the phylum Ciliophora, and when compared to actins from other organisms. To determine whether these primary structural differences are correlated with pharmacological differences, we investigated the effects of seven cytochalasins on phagocytosis, which has been shown to be actin‐dependent in eukaryotic cells. The relative potencies of cytochalasin inhibition of phagocytosis in Spirostomun ambiguum and Paramecium multimicronucleatum were similar. Dihydrocytochalasin B and cytochalasin A were the most potent of the seven cytochalasins in both ciliates, and strongly inhibited phagocytosis at 20‐40 μM. Dihydrocytochalasin B was considerably more potent than either cytochalasins B or D, a result unexpected on the basis of reports utilizing other organisms. However, even at concentrations up to 100 μM, dihydrocytochalasin B did not inhibit the rate of Spirostomum defecation. After long‐term treatment of Spirostomum with 50 μM dihydrocytochalasin B, the sensitivity of phagocytosis to the drug was reduced. These results indicate that the relative cytochalasin sensitivities of actin‐dependent functions in ciliates differ from those of other organisms, and are consistent with the hypothesis that sequence differences might give rise to substantial differences in the pharmacological properties of ciliate actins.

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“…Actin has been puri®ed in Climacostomum [18], Paramecium [49] and Tetrahymena [27]. In these ciliates, the puri®ed actin corresponds to a protein of about 43 kDa, if some confusing reports on Tetrahymena actin are not considered [39,41].…”

Section: The Proteinmentioning

confidence: 99%

Unusual characteristics of ciliate actins

et al. 2001

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Actin is a cytoskeletal protein that is ubiquitous in eukaryotes, hence the corresponding genes and proteins have been isolated from numerous organisms as dierent as animals, plants, fungi and protozoa. Several atomic models are available for the monomeric as well as the ®lamentous form, and more than 70 proteins that bind actin and control ®lament dynamics have been isolated from diverse eukaryotes. Moreover, the function and dynamics of the actin cytoskeleton in several eukaryotic systems have been depicted in depth. Unlike other protozoa, such as amoeba, actin is not an abundant protein in ciliates, whose cytoskeleton is mainly composed of microtubular arrays. Ciliate actin has been studied in several species, and it was established early on that this ciliate protein is very dierent from that of other eukaryotes. Similarly, the actin-binding proteins studied in ciliates display great dierences with those of other eukaryotes. Consequently, ciliate actin has been considered as``unconventional,'' and this review focuses on molecular data leading to this conclusion.

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Actin in the ciliated protozoan Climacostomum virens: Purification by DNAse I affinity chromatography, electrophoretic characterization, and immunological analysis

Cited by 9 publications

References 71 publications

Calcium in ciliated protozoa: Sources, regulation, and calcium-regulated cell functions

Calcium in ciliated protozoa: Sources, regulation, and calcium-regulated cell functions

Relative Potencies of Different Cytochalasins for the Inhibition of Phagocytosis in Ciliates

Unusual characteristics of ciliate actins

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