Taxonomic Criteria for Limax Amoebae, with Descriptions of 3 New Species of Hartmannella and 3 of Vahlkampfia*
TL;DR: The genus Hartmannella Alexeieff is re-defined to include those species which assume a simple, monopodial limax-like form during locomotion and have nuclear division similar to that of metazoan cells and to distinguish it from the genus Acanthamoeba Volkonsky, 1931.
Abstract: SYNOPSIS. Seven species of limax amoebae were isolated into clonal, monoxenic cultures with Aerobacter aerogenes from material collected from freshwater habitats. Studies were made of their trophic structure, nuclear division, cyst structure, some aspects of cytochemistry, and other characteristics. Six new species are described: Vahlkampfia inornata, V. avara, V. jugosa, Hartmannella limacoides, H. vermiformis, and H. exundans. The well-known species Naegleria gruberi (Schardinger, 1899) is re-described on the basis of 8 strains; its flagellated phase was found to be biflagellate, with rare exceptions.
A correlation exists between the manner of locomotion and the pattern of nuclear division in the limax amoebae in the family Vahlkampfiidae and those in the genus Hartmannella.
Trophic amoebae of all species had a PAS-positive surface layer, altho results with H. vermiformis and H. exundans were less definite than with other species. All species except H. limacoides formed cysts in culture. The cyst walls of all cyst-forming species were strongly PAS-positive, but results of the zinc chloroiodide test for cellulose were negative with the method used.
The genus Hartmannella Alexeieff, 1912, is re-defined to include those species which assume a simple, monopodial limax-like form during locomotion and have nuclear division similar to that of metazoan cells and to distinguish it from the genus Acanthamoeba Volkonsky, 1931.
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TL;DR: The current understanding of the burden of Acanthamoeba infections on human health, their pathogenesis and pathophysiology, and molecular mechanisms associated with the disease are presented, as well as virulence traits of AcanthamoebA that may be targets for therapeutic interventions and/or the development of preventative measures are presented.
Abstract: Acanthamoeba is an opportunistic protozoan that is widely distributed in the environment and is well recognized to produce serious human infections, including a blinding keratitis and a fatal encephalitis. This review presents our current understanding of the burden of Acanthamoeba infections on human health, their pathogenesis and pathophysiology, and molecular mechanisms associated with the disease, as well as virulence traits of Acanthamoeba that may be targets for therapeutic interventions and/or the development of preventative measures.
727 citations
TL;DR: The results indicate that, with energy supplied by plant roots or with external glucose additions, soil bacteria can mineralize N from the soil organic matter to support their own growth.
Abstract: Summary-The capacity of bacteria and protozoa to mineralize soil nitrogen was studied in microcosms with sterilized soil with or without wheat plants. The effect of small additions of glucose or ammonium nitrate or both, twice a week was also tested. Plant dry weight and N-content, number of microorganisms and biomass plus inorganic N were determined after 6 weeks. The introduction of plants profoundly influenced the N tr~sfo~ations. In the presence of root-derived carbon, much more N was mineralized from the organic matter and immobilized mainly in plant biomass. “Total observable change in biomass N plus inorganic N” was negative in the unvegetated soils without additions, while a mmeralization of 1.7 mg N microcosm-’ was observed in microcosms with wheat plants grown with bacteria only. When protozoa were included, the N taken up by plants increased by 75%. Sugar additions resulted in an 18% increase of total N in the shoots when protozoa were present, but had no significant effect in the absence of grazers. Plants with the same root weight were more efficient in their uptake of inorganic N when protozoa were present. Plants grown with protozoa also had a lower R/S ratio, indicating a less stressed N availabiIitv situatron. The lowest ratio was found with N additions m the presence of protozoa. The results indicate that, with energy supplied by plant roots or with external glucose additions, soil bacteria can mineralize N from the soil organic matter to support their own growth. Grazing of the bacteria is necessary to make bacterial biomass N available for plant uptake.
651 citations
Cites background from "Taxonomic Criteria for Limax Amoeba..."
...Amoebae saline (Page, 1967), mixed with washed growing bacteria originating from the same soil, served as food source for the protozoa....
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TL;DR: Microtubules in the cytoplasm of a small amoeba are described, believed to be a new species of the genus Hartmannella.
Abstract: INVESTIGATIONS of a wide range of cells have shown that microtubules, acting as skeletal elements, are associated with cytoplasmic movements1–3 Here I describe microtubules in the cytoplasm of a small amoeba, believed to be a new species of the genus Hartmannella4
341 citations
TL;DR: Of the three investigated groups—flagellates, ciliates, and amoebae—only populations of the latter were large enough and fluctuated in a way that indicated a role as bacterial regulators.
Abstract: Interactions between bacteria and protozoa in soil were studied over 2-week periods in the field and in a pot experiment Under natural conditions the total biological activity was temporarily synchronized by a large rainfall, and in the laboratory by the addition of water to dried-out soil, with or without plants In the field, peaks in numbers and biomass of bacteria appeared after the rain, and a peak of naked amoebae quickly followed Of the three investigated groups-flagellates, ciliates, and amoebae-only populations of the latter were large enough and fluctuated in a way that indicated a role as bacterial regulators The bacterial increase was transient, and the amoebae alone were calculated to be able to cause 60% of the bacterial decrease The same development of bacteria and protozoa was observed in the pot experiment: in the presence of roots, amoebic numbers increased 20 times and became 5 times higher than in the unplanted soil In the planted pots, the amoebic increase was large enough to cause the whole bacterial decrease observed; but in the unplanted soil, consumption by the amoebae caused only one-third of the bacterial decrease
314 citations
References
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TL;DR: The mercuric bromphenol blue reaction as used for development of protein spots on filter paper has been found to be applicable to the cytological staining of proteins, allowing good differentiation of structures often difficult to observe.
Abstract: 1. The mercuric bromphenol blue reaction as used for development of protein spots on filter paper has been found to be applicable to the cytological staining of proteins.2. The optimum procedure is identical in detail with that described by Kunkel and Tiselius for filter paper spots, except that a neutral aqueous solution is substituteed for ammonia vapor in the final color development.3. The sharp and intense staining of protein permits good differentiation of structures often difficult to observe, such as cilia, spindle elements, regions of spindle fiber attachment to chromosomes and "lamp brush" chromosomes.4. The procedure is specific for proteins and those peptides which are not removed in the washing procedure.5. The preparations stained by this procedure follow the Beer and Lambert Laws in microspectrophotometric measurements. The absorption maximum is at 610 millimicrons.6. Basic proteins bind the dye under the conditions of the method even when Hg is omitted. Other proteins bind the dye by coupli...
1,042 citations
TL;DR: Several major shifts of taxonomic significance have been introduced at all levels treated, including the subphyla, and these revisions are explained in appropriately placed footnotes.
Abstract: SYNOPSIS. A classification of the phylum Protozoa at supra-familial levels is given with definitions or descriptions of all of the involved taxa, some 140 in number. The scheme represents the result of the cooperative efforts of an international group of specialists and consultants who have‘been studying the overall problem for the past several years. Innovations of a nomenclatural nature have been held to a minimum, aside from the use of a system of uniform endings, but several major shifts of taxonomic significance have been introduced at all levels treated, including the subphyla. These revisions are explained in appropriately placed footnotes.
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TL;DR: A study of nine species of small free-living amoebae has been made under standardized and reproducible cultural conditions, by a new method that enables specimens in all stages of division to be obtained easily, and of two main types on which it is proposed to create two new families— Schizopyrenidae and Hartmannellidae.
Abstract: A study of nine species of small free-living amoebae has been made under standardized and reproducible cultural conditions, by a new method that enables specimens in all stages of division to be obtained easily. In all species the resting nucleus shows a Feulgen-negative nucleolus and Feulgen-positive chromatin granules. Nuclear division in these species and in other amoebae described by other workers is of two main types on which it is proposed to create two new families— Schizopyrenidae and Hartmannellidae. In Schizopyrenidae, the type genus Schizopyrenus n.g. and two other genera, Naegleria and Didascalus n.g., are defined. Naegleria gruberi, Didascalus thorntoni n.sp., Schizopyrenus russelli n.sp., S. erythaenusa n.sp. and S. atopus n.sp. are described. In Hartmannellidae the type genus Hartmannella is defined. H. glebae, H. rhysodes n.sp., H. leptocnemus n.sp and H. agricola are described. The relation of the proposed classification to previously defined families and genera of amoebae, and its bearing on phylogeny are discussed.
140 citations