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  • 2000-2004  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 47 (2000), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . In anticipation that improved knowledge of euglenid morphology will provide robust apomorphy-based definitions for clades, transmission and scanning electron microscopy were used to reveal novel morphological patterns associated with the euglenid pellicle. In some taxa, the number of pellicle strips around the cell periphery reduces as discrete whorls at the anterior and posterior ends of the cell. The number of whorls at either end varies between selected euglenid taxa but is invariant within a taxon. The pattern of strip reduction associated with these whorls is shown to have at least three evolutionarily linked states: exponential, pseudoexponential, and linear. Two general equations describe these states near the posterior end of euglenid cells. Exponential patterns of strip reduction near the anterior end are described by a third equation. In addition, several euglenid taxa were found to possess conspicuous pellicle pores. These pores are arranged in discrete rows that follow the articulation zones between adjacent strips. The number of strips between rows of pores varies between taxa and displays a series of consecutive character states that differ by a power of two. The patterns of pores may not only have phylogenetical and taxonomical value but may provide morphological markers for following strip maturation during cytoskeletal reproduction.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 48 (2001), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . The morphological diversity associated with the strip substructure of the euglenid pellicle was examined, and after identifying characters and states, we outlined hypotheses about their evolution. We have attempted to standardize terms necessary for analytical comparisons of strips by providing a glossary and comparing published synonyms. Most of the substructural diversity found in euglenids is demonstrated with 13 representative taxa. Strips are generally composed of two subcomponents: frames and projections. Frames support the basic shape of strips and many can be described as either S-shaped, plateau-shaped, M-shaped, or A-shaped. Projections branch laterally from the frames, are usually periodic, and can be described as thread-like structures, an indented plate, tooth-like structures, and plate-like structures. The ancestral state included strips that were few in number, flat, and fused. The strips became S-shaped and disjoined in the lineage leading to most euglenid taxa. These strips became secondarily flattened and fused in one lineage. In some lineages of phototrophs, the strips became increasingly robust. Two strips of different morphology formed the repeating pellicular unit or doublet in four taxa. These doublets evolved convergently at least three times and may provide insights into developmental patterns of the cytoskeleton.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillian Magazines Ltd.
    Nature 403 (2000), S. 77-80 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] It is generally agreed that the origin and initial diversification of Eucarya occurred in the late Archaean or Proterozoic Eons when atmospheric oxygen levels were low and the risk of DNA damage due to ultraviolet radiation was high. Because deep water provides refuge against ultraviolet ...
    Type of Medium: Electronic Resource
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