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  • 1
    Electronic Resource
    Electronic Resource
    Gamone Production in Large-Scale Cultures of Euplotes octocarinatus (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: We report a method that allows us to grow and maintain the freshwater ciliate Euplotes octocarinatus in large quantities. Frequent exchange of culture fluid proved more effective than aeration in obtaining high cell densities (4200 cells/ml) and reasonable doubling times in large-scale cultures. For harvesting gamone 1, the cell density was raised to 10,000 cells/ml. Under these conditions, the cells continued to produce and secrete gamone; they were slightly starved, but they no longer divided. Cell-free fluid with a steady and relatively high yield of gamone was obtained from two such cultures over a period of five months. We isolated gamone 1 also from cell homogenates and compared it with secreted gamone 1, but found no differences in the gamones from these two sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1988.tb04102.x
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  • 2
    Electronic Resource
    Electronic Resource
    Behavioural and morphological changes in ciliates induced by the predator Amoeba proteus (1993)
    Springer
    Oecologia 96 (1993), S. 354-359 
    Details
    ISSN: 1432-1939
    Keywords: Avoidance behaviour ; Defensive morphology ; Phenotypic plasticity ; Predation ; Protozoa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The predator Amoeba proteus induced behavioural and morphological changes in ciliates of the genus Euplotes. The frequency of avoidance behaviour in E. octocarinatus increased from 16±5% to 84±5% (SD) after 14 h of coexistence with the predator. The ciliate's width increased from 59±3 μm to 77±4 μm (SDM) within 48 h. Similar behavioural, but not morphological, change was induced in E. daidaleos, but neither morphological nor behavioural responses occurred in E. aediculatus. E. octocarinatus and E. daidaleos populations survived in the presence of A. proteus, whereas E. aediculatus populations became extinct by predation. Induced behavioural response seemed to be the reason for the low predation risk of E. octocarinatus and E. daidaleos. The results suggest that Euplotes ciliates have evolved specific defence mechanisms to various predators. Defensive changes are induced by a chemical substance released from A. proteus. This “kairomone” has a molecular weight between 5000 and 10000 Da. Proteolytic digestion of its activity indicated that the avoidance-inducing substance is a peptide. After the turbellarian Stenostomum sphagnetorum had induced a defensive morphology in E. octocarinatus or E. aediculatus, neither of these ciliates immediately avoided Amoeba proteus. Thus, Euplotes ciliates with a defensive morphology do not have behavioural defences in reaction to all predators.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317505
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  • 3
    Electronic Resource
    Electronic Resource
    Induction of defensive morphological changes in ciliates (1993)
    Springer
    Oecologia 94 (1993), S. 571-575 
    Details
    ISSN: 1432-1939
    Keywords: Predation ; Defence induction ; Interspecific recognition ; Defensive morphology ; Protozoa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Freshwater ciliates of the genusEuplotes change their morphology in response to the presence of predators. The morphological transformations limit the ability of the predators to ingest the ciliates. Induction of defensive morphology by the predatorsStenostomum sphagnetorum (Turbellaria),Lembadion bullinum (Ciliata),L. magnum, andAmoeba proteus (Rhizopoda) was studied inEuplotes aediculatus andE. octocarinatus. The results suggest the possibility of natural occurrence of predator-induced defensive morphology inEuplotes. A density of 1 predator ml−1 was sufficient to induce significant changes in the morphology ofEuplotes. L. magnum was found at natural population densities of 5 individuals ml−1. Transformations can take place within 2–4 h. Morphological changes are induced by signal substances released from the predators; direct contact between prey and predators is not necessary. The extent of transformation depends on the concentration of the signal substance. The size frequency distribution of the populations only had one peak that was related to predator density. All individuals of a population ofEuplotes changed their morphology according to the predator abundance. This may reduce energy costs for the prey by prevention of unnecessary morphological changes.Amoeba proteus induces morphological changes inE. octocarinatus, but not inE. aediculatus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566974
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  • 4
    Electronic Resource
    Electronic Resource
    Regulation aspects of roquefortine production by free and Ca-alginate immobilized mycelia of Penicillium roqueforti (1986)
    Springer
    Applied microbiology and biotechnology 23 (1986), S. 394-399 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Roquefortine synthesis with free and Ca-alginate immobilized Penicillium roqueforti cells was investigated under different culture conditions. Decreasing Ca-alginate concentration was related to increasing roquefortine production; free cells gave the best results. Formation of roquefortine was three times higher with mannitol and succinate than with sucrose as the carbon source; phosphate inhibited its biosynthesis in free cells by 23% to 32%. Relationships between cell density, 14C-tryptophan content of cells and roquefortine synthesis were shown. The special morphology of immobilized mycelia was demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00257040
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  • 5
    Electronic Resource
    Electronic Resource
    Genetic diversity in populations of a freshwater ciliate (2000)
    Springer
    Hydrobiologia 431 (2000), S. 185-192 
    Details
    ISSN: 1573-5117
    Keywords: ciliates ; conjugation ; freshwater habitat ; genetic diversity ; isolation ; population structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract RAPD fingerprinting with nine different primers revealed that all of 18 E. aediculatus isolates from nine ponds and streams in western Germany, France and the U.S.A. were genetically different. The extent of genetic similarity between genotypes from different waters did not show a significant relationship with the geographical distance among habitats, although genotypes isolated from the same habitat showed a higher genetic similarity than genotypes isolated from different habitats. Phylogenetic analyses of RAPD patterns indicate a separation of E. aediculatus strains into subgroups within one species, but all strains were genetically more similar to one another than to strains from two other Euplotes species. Crossings of the different E. aediculatus strains revealed they belonged to seven mating types of one gene pool. The high genetic diversity observed is explained by a frequent occurrence of conjugation in the studied populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004044314159
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  • 6
    Electronic Resource
    Electronic Resource
    Isolation of the Lembadion-factor, A morphogenetically active signal, that induces Euplotes cells to change from their ovoid form into a larger lateral winged morph (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 13 (1992), S. 241-246 
    Details
    ISSN: 0192-253X
    Keywords: Lembadion-factor ; cell-transformation ; Euplotes octocarinatus ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A morphogenetically active substance released by the predatory ciliate Lem-badion bullinum is recognized by ciliates of the genus Euplotes, which are potential prey organisms of Lembadion. The substance (L-factor) induces cells of the genus Euplotes to become less compact, which reduces their likelihood of becoming engulfed. Under the influence of this Lembadion- derived signal, E. octocarinatus develops extended wings and dorsal and ventral ridges and transforms within a few hours from its typical ovoid morph into an enlarged circular morph. This takes place without cell division. We have isolated the L-factor and report that it is a protein with a mass of 31,500 Da. The factor has been purified to chromatographic and electrophoretic homogeneity and was found to be active at concentrations as low as 10-12 mol/L. © 1992 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020130311
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