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  • 1
    Electronic Resource
    Electronic Resource
    Calcium Regulates the Regeneration of Cilia in Tetrahymena thermophila (1988)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 35 (1988), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A study of calcium metabolism in Tetrahymena during the regeneration of cilia evidenced that the process is inhibited by nifedipine and trifluoperazine. This suggests that calcium ions play an important regulatory role in this process. This was confirmed by studies on calcium uptake and efflux which showed that there was a net increase in calcium uptake prior to the reinitiation of motility. The increase coincided with a period of sensitivity to the calcium antagonist TMB-8 and with an increase in the intracellular level of cGMP. The process was also inhibited by neomycin and stimulated by phorbol esters, which suggests that hydrolysis of phosphatidylinositol phosphates may take place as part of the calcium regulatory network during the regeneration of cilia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1988.tb04119.x
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of Biogenic Amines on Phagocytosis in Tetrahymena thermophila (1987)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 34 (1987), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Stimulation of phagocytosis by serotonin and catecholamincs in Tetrahymena grown in proteose-peptone medium proved to be concentration dependent, the optimal concentrations being ∼0.1 to 1.0 μM. The serotonergic antagonists, spiperone, and metergoline, also stimulated the process, whereas the β- and α-adrenergic antagonists, propranolol, alprenolol, and ergocryptine, had no effect or inhibited phagocytosis. A wide variety of derivatives of the biogenic amines had no effect on phagocytosis, demonstrating the specificity of recognition mechanism for neurohormones in Tetrahymena. Such hormones act by at least two independent mechanisms, one for adrenergic agonists, another for dopamine. Presumably, recognition mechanisms for hormones in protozoa resemble in some respects those in multicellular organisms, therefore bespeaking a common origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1987.tb03208.x
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  • 3
    Electronic Resource
    Electronic Resource
    A Novel Opioid Mechanism Seems to Modulate Phagocytosis in Tetrahymena (1995)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 42 (1995), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . We have previously reported that a β-endorphin-like substance inhibits phagocytosis in Tetrahymena perhaps by a mu-like opioid receptor. We now report a further characterization of the elements involved in the signal transduction mechanism of this opioid. Affinity chromatography followed by immunoblots of both intracellular extracts and extracellular medium reveal the presence of two main proteins of 64 and 75 kDa. These molecular weights are much higher than that of any known opioid peptide or precursor protein and suggest that we may be dealing with either a novel opioid or with proteins that by chance cross-react with anti-β-endorphin antibody. Nevertheless, when the biological activity of these proteins was tested it was found that they had an effect similar to that of mammalian β-endorphin, namely inhibition of phagocytosis by a naloxone-reversible mechanism. We have probed a size-selected Tetrahymena library with a pro-opiomelanocortin probe and have obtained several positive clones; the sequencing of their inserts should establish whether we are dealing with a bona fide member of the opioid family. Another aspect we have been studying is the G-proteins which appear to be involved in the modulation of phagocytosis. We have found, by means of Western blotting (using an antibody against the conserved GTP-binding region of the α-subunit), two bands of 51 and 59 kDa; no α-subunit of 59 kDa had been reported previously and may represent a novel G-protein. In spite of these differences, the opioid signal transduction mechanism appears to remarkably resemble that present in more complex organisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1995.tb01566.x
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  • 4
    Electronic Resource
    Electronic Resource
    Opioid Activity of β-Endorphin-like Proteins from Tetrahymena (2004)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 51 (2004), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Morphine and other opioids have been reported to modulathd phagocytosis in the ciliate Tetrahymena. However, the endogenous signaling molecule responsible for these effects remains uncharacterized. In this work we present evidence for the presence of β-endorphin-like protein(s) in Tetrahymena thermophila. Subcellular extracts and cell-free culture supernatants were fractionated by hydrophobic chromatography on Sep Pack C18 columns and by affinity chromatography on polyclonal anti-β-endorphin columns. Both preparations exhibited opioid-like effects in two different systems: 1) they inhibited phagocytosis in murine peritoneal macrophages, and 2) they blocked the response to mechanical stimuli in the ciliate Stentor. Both of these effects were reversed by naloxone, consistent with an opioid receptor-mediated mechanism. Chromatographic (HPLC) fractionation of the subcellular extracts resolved a component with β-endorphin-like immunoreactivity, whose retention time was similar to that of the human β-endorphin standard. Fractions were also analyzed by immunoblots using a monoclonal antibody that recognizes the N-terminus of human β-endorphin. This antibody detected two antigenic components (corresponding to Mr 9,000 and Mr 12,000 polypeptides) in subcellular extracts, but only a single antigen (corresponding to a Mr 7,000 polypeptide) in culture supernatants. These results indicate that Tetrahymena produces one or more proteins that share some properties with β-endorphin and that these may form part of an opioid mechanism that originated early in evolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2004.tb00162.x
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  • 5
    Electronic Resource
    Electronic Resource
    Biogenic Amines Stimulate Regeneration of Cilia in Tetrahymena thermophila (1988)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 35 (1988), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Serotonin and catecholamines affect the regeneration of cilia in Tetrahymena thermophila in a dose-dependent manner: micromolar concentrations are stimulatory, whereas millimolar concentrations have little or no effect. This conclusion is based on motility measurements in regenerating cells and on ciliary counts in scanning electron micrographs. In addition, the recognition mechanism for each hormone appears to be specific and independent. Our results suggest an evolutionary link with hormonal mechanisms in multicellular eukaryotes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1988.tb04340.x
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  • 6
    Electronic Resource
    Electronic Resource
    Pharmacological Characterization of an Opioid Receptor in the Ciliate Tetrahymena (1993)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 40 (1993), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A pharmacological characterization has been performed of the opioid receptor involved in modulation of phagocytosis in the protozoan ciliate Tetrahymena. Studies on inhibition of phagocytosis by mammalian prototypic opioid agonists revealed that morphine and β-endorphin have the highest intrinsic activity, whereas all the other opioids tested can only be considered partial agonists. However, morphine (a mu-receptor agonist) is twice as potent as β-endorphin (a delta-receptor agonist). Furthermore, the sensitivity for the opioid antagonist naloxone, determined in the presence of morphine and β-endorphin, is very similar to the sensitivity exhibited by mammalian tissues rich in mu-opioid receptors. We suggest that the opioid receptor coupled to phagocytosis in Tetrahymena is mulike in some of its pharmacological characteristics and may serve as a model system for studies on opioid receptor function and evolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1993.tb04478.x
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  • 7
    Electronic Resource
    Electronic Resource
    Actin–tubulin homology revisited (1975)
    [s.l.] : Nature Publishing Group
    Nature 257 (1975), S. 601-602 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Evidence has been presented for6'7 and against8'9 the concept of homology between actin and tubulin, the monomeric unit of microtubules. (We use 'homology' in the sense defined by Stephens8.) Puszkin et a/.10'11 demonstrated that colchicine-binding protein isolated from porcine brain10 and blood ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/257601a0
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  • 8
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    cAMP uncouples DNA synthesis and cell division in Tetrahymena (1981)
    Elsevier
    Details
    Publication Date: 1981-10-01
    Print ISSN: 0014-4827
    Electronic ISSN: 1090-2422
    Topics: Biology , Medicine
    Published by Elsevier
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  • 9
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    Actin–tubulin homology revisited (1975)
    Springer Nature
    Details
    Publication Date: 1975-10-01
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Springer Nature
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