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  • 2005-2009  (3)
  • 1990-1994  (6)
  • 1975-1979  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Fine Structure Observations of Phagotrophic Activity By Plasmodia of Physarum Polycephalum (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: . Scanning electron microscopic observations of feeding plasmodia show three characteristic features: 1) extension of multilobed pseudopodia protruding from the leading edge of the plasmodium as it advances onto the surface of a food particle, 2) confluence of the lobes to form a sheath-like pseudopodium attached to the surface of the food particle, and 3) protrusion of small nodules with thin lamellar projections from the leading edge of the plasmodium. Sections through freeze-dried preparations of the feeding plasmodium exhibit a highly convoluted under surface in contact with loosened starch grains that appear to be released by extracellular digestion. the cytoplasm, viewed by transmission electron microscopy, contains branched, internally penetrating canals (ca. 2 μm wide) enclosing engulfed starch grains. Starch grains in the deeper part of the canals are more electron dense and appear to be digested. Micropseudopodia (70-80 nm dia.), projecting from the surface of the canals, protrude toward and into the ingested starch grains. Digestive marker enzyme (acid phosphatase) activity was detected cytochemically in food particles penetrated by micropseu-dopodia indicating a digestive role for these structures not reported previously.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1993.tb04884.x
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  • 2
    Electronic Resource
    Electronic Resource
    Fine Structure of the Marine Amoeba Vexillifera telmathalassa Collected from a Coastal Site Near Barbados with a Description of Salinity Tolerance, Feeding Behavior and Prey (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: . Amoebae cultured from seawater collected at a coastal site near Barbados were largely a lobose amoeba with long tapered subpseudopodia identified as Vexillifera telmathalassa. Vexillifera telmathalassa occurs widely in marine environments and additional information is presented here on its fine structure, salinity tolerance, and feeding behavior toward clarification of its taxonomic characteristics and ecological niche. The amoebae were able to adjust to a gradual decline in salinity from 36‰ to 16‰, but at a salinity of 12‰. They all became immobilized and discoidal. The fine structure showed a centrally located nucleus (2.1 μm) with a prominent nucleolus. The plasma membrane is coated with glycostyles 17 nm long and 14 nm apart, and may be derived from secretory vesicles with similar glycocalyx lining. Bacteria and occasional eukaryotic remains occur in digestive vacuoles or membrane-enclosed spaces. Some vacuoles (2.0–2.5 μm) are filled with scattered masses of digested material and resemble the “glanzkörper” previously identified by light microscopy. In addition to bacterial prey, microflagellates were also ingested in laboratory culture as observed by light microscopy. Vexillifera telmathalassa may be more closely linked trophically to the microbial loop than previously recognized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1994.tb01484.x
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  • 3
    Electronic Resource
    Electronic Resource
    A Fine Structure Study of Physarum polycephalum During Transformation from Sclerotium to Plasmodium: A Six-Stage Description (1992)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 39 (1992), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Physarum polycephalum is classified presently as a sarcodinid in the class Eumycetozoea. It produces a sclerotial dormant stage consisting of a crustose deposit containing nucleated spherules of cytoplasm enclosed within a honey-comb-like matrix of organic walls. When rehydrated, the sclerotium reverts to a plasmodium: 1) the spherules become increasingly vacuolated, 2) electron-dense granules become dispersed within expanding vacuoles, and 3) pseudopodial extensions develop from the periphery of the spherule cytoplasm, penetrating the fragmenting walls, and making interconnections with surrounding spherules, eventually leading to a fully reticulated plasmodium. Six stages are identified during reversion from sclerotium to plasmodium in laboratory cultures, and their successive appearance was mapped over time. The six stages are: 1) sclerotial stage with crenulated nuclei, 2) cytoplasmic activation with smooth nuclear envelopes, 3) initiation of pseudopodial protrusions, 4) pseudopodial penetration into or across walls, 5) cytoplasmic interconnections among spherules with wall disintegration, and 6) fully formed cytoplasmic network as plasmodium. Cytochrome c oxidase activity, expressed per unit protein content of the homogenate, remains fairly constant throughout the developmental sequence, whereas acid phosphatase activity, expressed per unit protein concentration, is somewhat lower in the sclerotium than in subsequent stages of development after hydration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1992.tb01305.x
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  • 4
    Electronic Resource
    Electronic Resource
    Laybourn-Parry, J. 1992. Protozoan Plankton Ecology. Chapman & Hall, New York. ISBN 0-412-34440-8. 231 pp. £99.00. (1992)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 39 (1992), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1992.tb04457.x
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  • 5
    Electronic Resource
    Electronic Resource
    Experimental studies of the relative effects of leaf litter from four hardwood trees on protozoan community productivity (2005)
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Leaf litter is an important source of organic matter as nutrients for aquatic and terrestrial microbial communities. Biogenic decomposition of leaf litter contributes substantially to atmospheric CO2, possibly producing global warming, and comprises an important part of the terrestrial carbon cycle. Small-scale variability in terrestrial protozoan communities may be attributed to localized variations in leaf matter. This study examined the effect of aqueous leaf extracts from four trees (beech, maple, red oak, and white oak) on the abundance and diversity of protozoa in laboratory aquatic and soil cultures. Beech leaf extract was the most productive followed in the descending order by white oak, red oak, and maple in both aquatic and soil microcosm cultures. Dilution experiments indicated that concentration-related inhibitory substance(s) in the maple and red oak leaves contribute to lower productivity. Removal of tannins by treatment with activated charcoal (Norit®) improved productivity especially for red oak leaf extracts, suggesting that tannins may contribute to the inhibition of protozoan standing stock. To determine if the lower productivity was mainly due to the inhibition of protozoan excystment, aliquots of thoroughly dried soil were inoculated into maple and red oak leaf extracts. A comparable growth of protozoa occurred in these treatments as in aliquots from moist soil indicating that inhibition of excystment is not a likely explanation for reduced productivity of the protozoan communities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2005.05202003_1_4.x
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of Aqueous Extracts from Leaves and Leaf Litter on the Abundance and Diversity of Soil Gymnamoebae in Laboratory Microcosm Cultures (2005)
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. The distribution and abundance of microbiota in soil and litter may be significantly affected by the quality and quantity of localized patches of leaf organic matter. This study examined the relative effects of aqueous extracts of shed autumn leaves from American beech (Fagus grandifolia), sugar maple (Acer saccharum), red oak (Quercus rubra), and white oak (Quercus alba) on the density and diversity of gymnamoebae in laboratory cultures. Overall, the beech leaf extract produced the most growth of gymnamoebae followed by white oak with leaf extracts from maple and red oak producing least growth. Cultures using natural leaf litter from beneath beech trees had higher densities and diversity of gymnamoebae than leaf-litter cultures from a maple–oak stand. Soil microcosms confirmed that beech leaf extracts produced a higher density of gymnamoeba growth when added to soil cultures compared with maple and oak leaf extracts. Protein content, CHN (carbon and nitrogen content), and pH of the leaf extracts were assayed, but these alone were not sufficiently different to account for the effects. A dilution experiment indicated that some other concentration-dependent factor in the extract may produce the effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2005.00052.x
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  • 7
    Electronic Resource
    Electronic Resource
    Fine Structure of a Marine Ameba Associated with a Blue-Green Alga in the Sargasso Sea, (1977)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 24 (1977), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS An ameba, bearing a fringe of scales on the plasmalemma surface, dwells among the filaments of the colonial, blue-green alga Trichodesmium thiebautii (Sournia), and preys upon bacteria growing within the colony. The cytoplasm is clearly differentiated into a fine fibrillar ectoplasm at the periphery of the cell and a central endoplasm containing most of the membranous organelles. The nucleus contains a spheroidal nucleolus which is centrally located, and a double membrane containing pores. The tubular mitochondria, microbodies, lysosomes, and endoplasmic reticulum are typical for protozoa. The Golgi apparatus consists of an array of elongate flattened cisternae. One surface is associated with a fine fibrillar layer and the opposite surface contains electron-dense vesicles (perhaps primary lysosomes) and scale-containing vesicles that appear to be the origin of the scales deposited on the plasma membrane. Three kinds of bacteria-containing vacuoles are presnt: (a) vacuoles surrounded by 3 membranes and containing bacteria that are either healthy or in an early stage of digestion, (b) singlemembrane vacuoles which are food vacuoles that become converted to digestive vacuoles, and (c) larger vacuoles resembling those in (b) which contain prey in an advanced stage of digestion. The presence of amebae within pelagic algal communities provides further evidence for the diversity of their habitats in the ocean.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1977.tb04753.x
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  • 8
    Electronic Resource
    Electronic Resource
    The New Higher Level Classification of Eukaryotes with Emphasis on the Taxonomy of Protists (2005)
    Malden, USA : Blackwell Publishing Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. This revision of the classification of unicellular eukaryotes updates that of Levine et al. (1980) for the protozoa and expands it to include other protists. Whereas the previous revision was primarily to incorporate the results of ultrastructural studies, this revision incorporates results from both ultrastructural research since 1980 and molecular phylogenetic studies. We propose a scheme that is based on nameless ranked systematics. The vocabulary of the taxonomy is updated, particularly to clarify the naming of groups that have been repositioned. We recognize six clusters of eukaryotes that may represent the basic groupings similar to traditional “kingdoms.” The multicellular lineages emerged from within monophyletic protist lineages: animals and fungi from Opisthokonta, plants from Archaeplastida, and brown algae from Stramenopiles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2005.00053.x
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  • 9
    Electronic Resource
    Electronic Resource
    The fine structure of the encysting salt marsh heterotrich ciliate Fabrea salina (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 205 (1990), S. 335-341 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Wall and internal organelles of the encysting salt marsh heterotrich ciliate Fabrea salina were examined by bright field and Nomarski interference contrast microscopy and by transmission and scanning electron microscopy. A mucoid sheath believed to be derived from bacteria covers the ectocyst. The possible bacterial origin of this sheath has been demonstrated experimentally by its removal and reappearence after 24 hours. Control ectocyst maintained in sterile seawater did not replace the sheath. The ectocyst has a crinkled appearance. The endocyst is composed of two layers. The inner endocyst material is continuous with that of the plug located at one end of the cyst. The two membranes are separated from one another by an interwall space filled with fibrous material. The cytoplasm, covered by an outer double membrane pellicle, contains mucocysts, pigment granules, microtubules, non-ciliated kinetosomes, Golgi complexes, ribosome-studded endoplasmic reticulum, and mitochondria. The endoplasm contains numerous autophagosomes, mitochondria, and food reserve materials. The macronucleus is centrally located in the cytoplasm of the encysting organism.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052050308
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  • 10
    Electronic Resource
    Electronic Resource
    The effects of silicate depletion and subsequent replenishment on the cytoplasmic fine structure of the silica-secreting testate amoeba Netzelia tuberculata in laboratory culture (1992)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 211 (1992), S. 285-293 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the absence of silicate in the growth medium, Netzelia tuberculata cells withdraw their feeding lobopodia, become quiescent, and cease to divide. Upon replenishment of silicate, growth resumes within 18-24 hours. Cytoplasmic changes produced by a low silicate medium result in a zonal arrangement, with siliceous particles at the outer periphery of the cytoplasm in a region rich in Golgi bodies (Region A), a more centrally located layer containing endoplasmic reticulum, lipid reserves, and finely granular cytoplasm (Region B), and a region of partially digested food and waste material fringed by fine rhizopodia extending into the central space of the test (Region C). The reserve siliceous particles in the outer peripheral cytoplasm are foreign particles that contain a fragile deposit of silica and appear to be incomplet. This may be a mechanism for conserving silica in the low-silicate medium by coating particles instead of making particles of solid silica de novo. Upon addition of silicate to the growth medium, new siliceous particles are synthesized within vacuoles in the region of the Golgi apparatus within 2-18 hours. Vacuoles containing fine silica deposits, characteristic of new particle production, are surrounded by Golgi-derived vesicles previously shown to be a source of membrane for the silica-secreting vacuoles. The newly synthesized particles are solid silica as is characteristic of de novo secreted test particles, in contrast to the numerous silica-coated foreign bodies found in quiescent cells produced in low-silicate medium.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052110306
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