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  • 2005-2009  (3)
  • 1975-1979  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    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
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    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
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 24 (1977), S. 0 
    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
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  • 4
    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
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