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  • 1
    Electronic Resource
    Electronic Resource
    Morphological Drift Accompanying Nascent Population Differentiation in the Ciliate Euplotes vannus (1990)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 37 (1990), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A rare phenomenon can occur in ciliated protists of the genus Euplotes, which can undergo genetic recombination by the normal outbreeding process of conjugation following mild starvation. Occasionally, the dominant mutation for the autogamy trait arises. Individuals possessing the trait show obligate self-fertilization upon mild starvation. This yields, after normal asexual division, a population of individuals that are reproductively isolated from the parental outbreeding strain. A morphometric analysis of sympatric autogamous and non-autogamous populations of Euplotes vannus from Somalia demonstrates that there has been morphological drift in gross body proportions in the autogamous populations. However, the positional patterns of the locomotory organelles on the ventral surface remain unchanged. The changes in body proportions in the autogamous populations are relevant to the mechanics of the conjugation process, which involves fusion of the oral regions of paired cells belonging to complementary mating types.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1990.tb05874.x
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  • 2
    Electronic Resource
    Electronic Resource
    The Excystment Process in the Ciliate Euplotes muscicola: An Integrated Light and Scanning Electron Microscopic Study (1985)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 32 (1985), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Resting cysts and the excystment process in the freshwater ciliate Euplotes muscicola were studied by both light and scanning electron microscopy. Groups of distinctly crested resting cysts adhere to the substrate. Silver-stained preparations reveal surface conservation of dorsal kinetosomes and dorsal argyrome while ventral organelles are directed inward. Excystment involves the development of an expanding excystment vacuole concurrent with a localized thinning on the dorsal cyst wall surface. Cells exit through the pre-formed ostiole, mid-dorsal region first, initially by the force of cytoplasmic streaming, but later aided by cirral movement. Newly emerged cells retain the excystment vacuole and show no dorsal ridging. As the cell expels its excystment vacuole and partially unfolds, normal trophont morphology is re-established. Both cyst structure and cyst typology have implications for hypotrich taxonomy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1985.tb03109.x
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  • 3
    Electronic Resource
    Electronic Resource
    A Morphometric Analysis of the Euplotes charon Morphotype (Ciliophora: Euplotida) (1994)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 41 (1994), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Twenty-one different strains of Euplotes of the cirrotype 10, double dargyrome morphotype were collected in marine and brackish habitats from widely varying geographic locations. The strains were cultured under similar conditions prior to fixation and staining. The morphological features considered included the cell lengths and widths, the number and position of all the ventral cirri, adoral membranelles and dorsal cilia, and the position of the peristomal shelf. Univariate and multivariate analyses revealed continua in these measurements among the strains, as well as significant correlations between cell length and the number of adoral membranelles, the number of dorsal cilia, and the length, width and area of the oral cavity. Based on data from this study and from previous studies, we conclude that the traditional criteria used for species descriptions within this morphotype are insufficient to provide robust distinctions. Therefore, we submerge all of the descriptions within this morphotype under the nomenclaturally superior Euplotes charon Müller, 1786.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1994.tb06040.x
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  • 4
    Electronic Resource
    Electronic Resource
    Quantitative Analyses of Interbreeding in Populations of vannus-Morphotype Euplotes, with Special Attention to the Nominal Species E. vannus and E. crassus (1994)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 41 (1994), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Classical genetic techniques were applied to clonal cultures of the Euplotes vannus-crassus-minuta sibling species complex in an effort to provide some resolution to the species problem among these hypotrichs. Complex mating interactions were observed among clonal stock cultures derived from samples collected from sympatric and allopatric populations in a wide geographic survey. These results suggested that the classical model for the mating type inheritance and determination in these Euplotes is necessary but not sufficient to describe the mating mating interactions among populations of these ciliates. Successful conjugation between the nominal species E. crassus and E. vannus was observed routinely, and crosses between these two nominal species did not differ significantly from those among the other clonal stock cultures with respect to mating intensity and exconjugant survival. Data from backcrosses suggests that E. vannus and E. crassus can and do exchange genes. Based upon these data, we conclude that E. vannus and E. crassus comprise a single, highly polymorphic species with countless small populations, among which incomplete genetic exchange takes place.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1994.tb06084.x
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  • 5
    Electronic Resource
    Electronic Resource
    A Morphometric Study of Euryhalinity in Marine Populations of the Ciliate Genus Euplotes (1994)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 41 (1994), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Twenty different clonal strains of marine and brackish Euplotes, representing four morphotypes, were tested for hyposalinity tolerance by a method which gradually acclimated the cells to lower salinity medium. The lowest salinities in which the strains could thrive ranged from 60% of normal seawater to complete freshwater. The morphological effects of culture medium salinity were also examined for two strains of a small “Euplotes charon” morphotype, as well as for two mating compatible “Euplotes vannus” strains and several of their exconjugates. There were no differences between the euryhaline strains grown in fresh or saltwater, except for a slight increase in overall cell size in one strain when cultured in freshwater medium. E. vannus strains increased in overall cell size with decreased salinity; also, the dorsal surface of the cells can become disorganized when the cells are cultured in 30% normal seawater.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1994.tb06083.x
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  • 6
    Electronic Resource
    Electronic Resource
    Morphometric Variation in the Hypotrich Ciliate Genus Euplotes (1978)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 25 (1978), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. A quantitative method for the analysis of cirral patterns in the genus Euplotes is developed and contrasted with alternative approaches. Inherent variations in cirral pattern, as they are reflected in frequency distributions of intercirral distances, are ascertained through subclonal analyses of Euplotes harpa samples grown under different conditions. This assessment of the extent of variation within a form having 10 frontoventral cirri provides a basis for a comparative study of other Euplotes of cirrotype 10. These results suggest that all marine cirrotype 10 forms with a single dargyrome have the same configuration of frontoventral and transverse cirri. Similarly, most marine double dargyrome forms of cirrotype 10 have this same cirral pattern, and thus constitute variations upon the same morphometric theme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1978.tb03900.x
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  • 7
    Electronic Resource
    Electronic Resource
    A radiation hybrid map of the zebrafish genome (1999)
    [s.l.] : Nature America Inc.
    Nature genetics 23 (1999), S. 86-89 
    Details
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Recent large-scale mutagenesis screens have made the zebrafish the first vertebrate organism to allow a forward genetic approach to the discovery of developmental control genes. Mutations can be cloned positionally, or placed on a simple sequence length polymorphism (SSLP) map to match them with ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/12692
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  • 8
    Electronic Resource
    Electronic Resource
    Analysis of positional information applied to cirral patterns of the ciliate Euplotes (1977)
    [s.l.] : Nature Publishing Group
    Nature 268 (1977), S. 362-364 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The ventral surface of Euplotes (Fig. 1) bears a system of morphogenetically unified landmarks, the frontoventral and transverse cirri, which arise during asexual division from subpellicular kinetosomal plaques. These compound ciliary organelles develop from the simultaneous elongation and ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/268362a0
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  • 9
    Electronic Resource
    Electronic Resource
    Zebrafish organizer development and germ-layer formation require nodal-related signals (1998)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 395 (1998), S. 181-185 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The vertebrate body plan is established during gastrulation, when cells move inwards to form the mesodermal and endodermal germ layers. Signals from a region of dorsal mesoderm, which is termed the organizer, pattern the body axis by specifying the fates of neighbouring cells,. The organizer is ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/26013
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  • 10
    Electronic Resource
    Electronic Resource
    Dry to wet weight biomass conversion constant for Tetrahymena elliotti (Ciliophora, Protozoa) (1982)
    Springer
    Oecologia 55 (1982), S. 145-148 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The wet and dry weights of both axenic and monoxenic cultures of the ciliate Tetrahymena were determined directly. These estimates are dependent upon the method of volume determination. Assuming a prolate spheroidal shape for the ciliate, we calculate a mean wet weight of 0.4157±0.0713 pg μm-3 and a mean dry weight of 0.2793±0.0652 pg μm-3. Using electronic cell sizing, our estimates are 0.7869±0.1659 pg μm-3 and 0.5239±0.1101 pg μm-3, respectively. Independent of the method of volume determination, we estimate a mean biomass conversion ratio (dry weight/wet weight) of 0.59±0.08.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384479
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