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  • Articles  (15,237)
  • Elsevier  (13,094)
  • Blackwell Publishing Ltd  (2,143)
  • American Institute of Physics (AIP)
  • 2020-2023
  • 1990-1994  (15,237)
  • 1935-1939
  • 1991  (15,237)
  • Biology  (15,237)
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  • Articles  (15,237)
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  • 2020-2023
  • 1990-1994  (15,237)
  • 1935-1939
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  • 1
    Electronic Resource
    Electronic Resource
    The Axenic Cultivation of Insect Forms of Trypanosoma (Duttonella) vivax and Development to the Infective Metacyclic Stage (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A method for axenic cultivation of epimastigote and metacyclic forms of Trypanosoma (Duttonella) vivax at 27°C in vitro is described. Iscove's medium was supplemented with specific concentrations of foetal bovine serum, L-proline, L-glutamine, hypoxanthine, adenosine, pyruvate, and 2-mercaptoethanol. Bloodstream form parasites rapidly transformed into epimastigote forms that grew as surface-adherent colonies in plastic culture flasks. Transformation of epimastigotes to metacyclic forms was first observed 9–12 days after initiation of cultures. Percentages of metacyclics varied: East African T. vivax ranged up to 40% and West African T. vivax ranged up to 24%. Subcultures were made at two-week intervals and maintained for several months. Transformation of bloodstream forms to epimastigotes depended on initial attachment to the bottom of culture flasks and the presence of L-proline. The number and maturity of metacyclic forms was influenced by the concentrations of foetal bovine serum, L-proline, L-glutamine, and 2-mercaptoethanol. Trypanosomes from cultures were cryopreserved, revived, and used to re-establish fresh axenic cultures. These results represent a significant advance in cultivation of T. vivax insect forms that should enable studies to be accomplished on metabolism, differentiation, and pharmacology of this parasitic protozoan, free from the influence of extraneous cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04424.x
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  • 2
    Electronic Resource
    Electronic Resource
    A Soluble Phospholipase of Toxoplasma gondii Associated with Host Cell Penetration (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We previously reported that phospholipase increases host cell penetration by Toxoplasma gondii. Here we show that calcium-dependent phospholipase A (PLA) activity is found in the supernatant of sonically disrupted T. gondii. When fractions of disrupted T. gondii were incubated with host cells, the release of fatty acids and lysolipids was detected. Fractions of sonically disrupted T. gondii with PLA activity increased T. gondii host cell penetration in a bioassay. In addition, a protein of approximately 20 kDa was detected by immunoblot of T. gondii antigens with horse antiserum to snake venom, the major antibody of which recognizes PLA2. Incubation of T. gondii with exogenous PLA2 resulted in increased solubility of a rhoptry protein. This protein, which we previously characterized as involved with enhanced parasite invasion of host cells and which is recognized by monoclonal antibody Tg49, was detected in increased amounts in supernatant fractions of extracellular parasites treated with PLA2. Whereas without PLA2 treatment, it is only slightly soluble under physiological conditions. This raises the possibility that PLA may be implicated in the release of rhoptry proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04816.x
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  • 3
    Electronic Resource
    Electronic Resource
    Enhanced Uptake and Metabolism of Riboflavin in Erythrocytes Infected with Plasmodium falciparum (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Riboflavin deficiency inhibits the growth of malaria parasites both in vitro and in vivo in infected animals and humans. Although the precise mechanisms underlying this inhibition are unknown, they may involve enhanced requirements for riboflavin by parasites. To investigate this possibility, the rate of uptake of [14C]riboflavin and the biosynthesis of FMN and FAD from riboflavin were studied in infected (5–8% parasitemia) and uninfected human erythrocytes. All cells were incubated for 0–3 h at 37° C in phosphate buffered saline containing MgCl2, glucose, and [14C]riboflavin (2.5–7.5 μM). At hourly intervals, samples were removed, centrifuged, washed twice with cold buffer, and lysed before counting the radioactivity. The rate of in vitro biosynthesis of FMN and FAD from riboflavin in erythrocytes was measured by ion exchange chromatography and reverse isotope dilution techniques. Results showed that the rate of riboflavin uptake and the biosynthesis of FMN and FAD were enhanced in erythrocytes with parasitemia as compared with results in unparasitized erythrocytes. Riboflavin uptake in erythrocytes was proportional to the extent of parasitemia and especially to percent of schizonts present in erythrocytes. These studies indicate that the requirement for riboflavin may be greater in the parasite than in the host erythrocyte. This increased riboflavin requirement may be due to rapid multiplication, higher metabolic rate, and extreme vulnerability to oxidative stress of malaria parasites compared with that of host erythrocytes. The differential requirement of riboflavin by the host and the malaria parasite may hold important potential for developing new strategies for malaria chemotherapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04820.x
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  • 4
    Electronic Resource
    Electronic Resource
    German Section Society of Protozoologists 9th Annual Meeting (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), 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.1550-7408.1991.tb04786.x
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  • 5
    Electronic Resource
    Electronic Resource
    Phylogenetic Relationships of Blepharisma Americanum and Colpoda Inflata Within the Phylum Ciliophora Inferred From Complete Small Subunit Rrna Gene Sequences (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The complete small subunit rRNA gene sequences of the heterotrich Blepharisma americanum and the colpodid Colpoda inflata were determined to be 1719 and 1786 nucleotides respectively. the phylogeny produced by comparisons with other ciliates indicated that C. inflata is allied more closely with the nassophoreans and oligohymenophoreans than the spirotrichs. This is consistent with the placement of the colpodids in the Class Copodea. Blepharisma americanum was not grouped with the hypotrichs but instead was placed as the earliest branching ciliate. the distinct separation of B. americanum supports the elevation to class status given the heterotrichs based on morphological characters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04783.x
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  • 6
    Electronic Resource
    Electronic Resource
    Endosymbiotic Methanogenic Bacteria In Anaerobic Ciliates: Significance For the Growth Efficiency of the Host (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Endosymbiotic methanogenic bacteria of three species of anaerobic ciliates (Plagiopyla frontata, Metopus conforms, and M. palaeformis) were inactivated with the specific methanogen inhibitor 2-bromoethanesulfonic acid. the absence of endosymbiont methanogens reduced growth rate and growth yield by about 30% in P. frontata and M. contortus, while no significant change in fitness was observed in M. palaeformis. In Plagiopyla the growth rate constant is not affected by an artificially increased pH2 neither in normal nor in methanogen-free ciliates. the energetic advantage conferred by endosymbiont methanogens in Plagiopyla and in Metopus contortus probably is due to excretion of organic material from the bacteria at the expense of bacterial reproduction. It is unlikely that the maintenance of a low pH2 within the cells due to H2-consumption by the bacteria is important to the ciliates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04788.x
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  • 7
    Electronic Resource
    Electronic Resource
    Coccidia of Brazilian Mammals: Eimeria Marajoensis N. Sp. (Apicomplexa: Eimeriidae) From the Anteater, Tamandua Tetradactyla (Xenarthra: Myrmecophagidae) (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Feces from a juvenile specimen of the anteater Tamandua tetradactyla from Ponta de Pedras, Marajó, Pará, northern Brazil, contained three different coccidial oocysts: Eimeria tamanduae Lainson, 1968; E. corticulata Lainson & Shaw, 1990; and a third species previously unrecorded and described here as Eimeria marajoensis n. sp. Oocysts of the latter parasite are spherical to subspherical, 13.9 ± 1.5 times 13.4 ± 1.4 (11.1-16.5 times 11.1-16.5) μm, shape index (length/width) 1.0 (1.0-1.2). the oocyst wall is a single, Colorless layer about 0.6-1.0 μm thick with no striations or micropyle. There is no oocyst residuum, but a single, round, oval or irregularly shaped polar granule of about 0.75-2.5 μm is consistently present. the sporocysts are broadly ellipsoidal, 7.1 ± 0.7 ± 5.3 ± 0.6 (6.0-8.8 times 4.0-5.7) μm, shape index 1.3 (1.2-1.5), with a delicate wall bearing a minute stieda body. No sub-stieda body was visible. the sporocyst residuum consists of some 10-20 rounded granules, lying between the two slightly curved sporozoites which measure approximately 6.5 times 2.0 μm. Sporocyst refractile bodies were not discernablc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04792.x
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  • 8
    Electronic Resource
    Electronic Resource
    In Vitro Development of Exoerythrocytic Forms of Plasmodium Gallinaceum Sporozoites In Avian Macrophages (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Exoerythrocytic forms of Plasmodium gallinaceum were cultured in vitro using salivary gland sporozoites extracted from experimentally infected Aedes fluviatilis mosquitoes. the host cells were macrophage precursors from chicken bone marrow. At various times after introduction of Sporozoites, the cultures were stained by Giemsa or by immunofluorescence assay (IFA) using anti-sporozoite-specific monoclonal antibodies (MAb). the time to complete parasite development in vitro was 50-70 h. By 70 h, ruptured segmenters and free merozoites were visible within the cells. Inoculation of normal chickens with infected cultures induced parasitemia after a pre-patent period of 10-11 days. In vitro young exoerythrocytic forms, late schizonts that include the matured segmenters, and free merozoites shared common antigens with the sporozoites as revealed by IFA using anti-sporozoite-specific MAbs. Our data indicate that macrophages support development of P. gallinaceum sporozoites and that the circumsporozoite proteins are present until Ac end of the primary exoerythrocytic schizogony.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04796.x
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  • 9
    Electronic Resource
    Electronic Resource
    The Patterning of Ciliates (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: This past-presidential address considers the relationship between small-scale assembly and large-scale patterning in ciliates. Certain model examples of assembly-based patterning are reviewed, followed by the introduction of Williams and Honts' concept of “meta-assembly” as applied to the development of the oral apparatus. The major part of this review then explores two topics: the nature and origin of large-scale circumferential order, and the manner by which the large-scale order of cell directions influences the organization of membranelles of the oral apparatus. In this review, I summarize an existing formal description of large-scale positional order, allude to a more precise abstract theoretical model, and end with a brief discussion of the problem of searching for molecular mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04827.x
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  • 10
    Electronic Resource
    Electronic Resource
    The Fine Structure of the Cinctum of Ellobiophrya conviva (Ciliophora: Peritricha) (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Ellobiophrya conviva clasps tentacles of the bryozoan Bugula neritina with a ring-like structure formed from aboral extensions of its body that taper into two slender arms. The tips of the arms overlap and join to form a unique organelle, the bouton. Each arm contains a massive myoneme that splays out at the bouton. The bouton consists of the cupped tips of the arms and a cavity, which is filled with dense homogeneous material. Long digitations containing longitudinal microtubules at their periphery project from the inner surface of the tip of each arm into the cavity. Deep folds of pellicle with pores opening into their depths line the wall of the cavity. Conventional kinetosomes are not visible in the bouton, but circular or elliptical arrays of microtubules are found at the bases of digitations. The nonfunctional scopula of the adult is in a depression enclosed by pellicular folds. The bouton is distant from the scopula, but its fine structure somewhat resembles it, supporting Chatton and Lwoff's hypothesis that the cinctal arms carry parts of the scopula at their tips. The fine structure of the cinctum supports their suggestion that the cinctal arms are homologous to the spasmonemes of vorticellid peritrichs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb01365.x
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  • 11
    Electronic Resource
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    Reactivity of Monoclonal Antibodies to Species-Specific Antigens of Entamoeba histolytica (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Twenty monoclonal antibodies were produced against trophozoites of Entamoeba histolytica strains HK-9 and HM-1: IMSS. When reactivity to various enteric protozoa was examined by an indirect fluorescence antibody test, 15 of the monoclonal antibodies were strongly reactive with E. histolytica trophozoites. Species-specific antigens recognized by these monoclonal antibodies were located on the plasma membrane, nucleus, cytoplasm, and cytoskeletal structures of the trophozoites. Two of the remaining five monoclonals reacted strongly with trophozoites of the E. histolytica-like Laredo strain. The determinant antigen was located in the cytoplasm. The three remaining monoclonal antibodies were found to recognize cross-reactive antigens between E. histolytica and E. histolytica-like Laredo, E. hartmanni, E. coli, Dientamoeba fragilis, Giardia lamblia, and Trichomonas hominis. These three antibodies were also reactive with T. vaginalis
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb01368.x
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  • 12
    Electronic Resource
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    The Effect of the Lipogenic Inhibitor Cerulenin, on Macrostomal Cell Formation in Tetrahymena vorax (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Macrostomal cell formation is blocked by the antibiotic cerulenin at levels of 15 μg/ml or higher. Inhibition can be reversed up to 4 h following cerulenin addition by washing and resuspending cells in new, noncerulenin-treated transforming principle. In these latter cases, additional time equal to the time spent in the inhibitor, is needed for cells to reach control values of transformation. Neither the addition of saturated or unsaturated fatty acids, cholesterol added alone or in combination with stearic acid, nor a mixture of lipids extracted from Tetrahymena vorax reversed the cerulenin effect. Radioisotope incorporation data showed while protein synthesis was reduced by the end of 1 h and tetrahymanol synthesis by the end of 2 h, little or no effect of this inhibitor occurred on RNA or fatty acid synthesis during these times. One interpretation of these results is that cerulenin, by preventing first protein synthesis and later tetrahymanol synthesis, interferes with synthesis and formation of membranes required for the microstome to macrostome transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb06031.x
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  • 13
    Electronic Resource
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    ERRATUM (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    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.1550-7408.1991.tb06038.x
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  • 14
    Electronic Resource
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    Israeli Section Society of Protozoologists (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    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.1550-7408.1991.tb04787.x
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  • 15
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    Groupement des Protistologues de Langue Francaise (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), 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.1550-7408.1991.tb04791.x
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  • 16
    Electronic Resource
    Electronic Resource
    Italian Section Society of Protozoologists (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), 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.1550-7408.1991.tb04794.x
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  • 17
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    Microfilum Lutjani N. G. N. Sp. (Protozoa Microsporida), A Gill Parasite of the Golden African Snapper Lutjanus Fulgens (Valenciennes, 1830) (Teleost Lutjanidae): Developmental Cycle and Infrastructure (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Microfilum lutjani n. g., n. sp. (Microsporida) was found on the gill filaments of Lutjanus fulgens (Teleost) inhabiting the coasts of Senegal. This microsporidium forms xenomas distinguished by the microvilli covering the plasma membrane. At all stages of development individuals have isolated nuclei and are in direct contact with the host cytoplasm. Merogony is binary and sporogony is tetrasporoblastic. the spore (4.75 times 2.60 μm)) is characterized by a manubrium inserted on a laterally offset anchoring disc and extending into a very short, noncoiled polar filament (no longer than 500 nm) in the form of a hook. This type of polar filament has not been described previously in the Microsporida.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04793.x
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  • 18
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    Geosmin As an Odorous Metabolite In Cultures of A Free-Living Amoeba, Vannella Species (Gymnamoebia, Vannellidae) (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Geosim was identified as the cause of a distinct earthy/grassy odour detected in cultures of a free-living amoeba, Vannella species. Volatile components of cell lysates were isolated and concentrated by the Closed Loop Stripping method. Capillary, gas chromatography/mass spectrometry was used to identify odorous compounds. Bacterial symbionts observed in the cytoplasm of the amoebae may be responsible for production of the geosmin. This appears to be the first report of odorous compounds associated with a free-living protozoan and suggests that in some circumstances, Vannella sp. may contribute to taste and odour problems in drinking water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04798.x
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  • 19
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    Feeding In Planktonic Protozoans: Evidence For Non-Random Acquisition of Prey (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The literature on discriminant feeding by planktonic protozoans using geometric and nongeometric criteria is reviewed with emphasis on recent studies that indicate phagotrophic protists can use information other than particle size or shape to sort among potential prey. Sufficient data are available for ciliates, aplastidic microflagellates, and phagotrophic dinoflagellates. Numerous representative taxa of all three groups have chemosensory capabilities, either to specific chemicals or to prey exudates, that modify their motility patterns resulting in aggregation or dispersal. Representatives of all three groups also have specific prey preferences. These considerations imply, but do not prove, selectivity in feeding through use of chemical cues. Although prey geometry is clearly a first-order determinant of ingestion through passive mechanical selection, recent studies illustrate that planktonic ciliates and flagellates can use other criteria to discriminate among prey. the evidence clearly implicates use of chemical cues, most likely perceived through contact chemoreception. Filter feeders as well as raptors have such abilities indicating that feeding mechanisms per se do not imply limitations on feeding behavior. Evidence of considerable flexibility and complexity in chemoperceptive feeding suggests that we have only glimpsed the more detailed features of feeding behavior in aquatic protozoans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04804.x
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  • 20
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    Comparative and Experimental Approaches to the Study of Microbial Food Webs (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The study of microbial food webs is dominated by field measurements of microbial standing stocks and rate processes and to a lesser extent by laboratory studies. These approaches reflect the concerns of microbial ecologists to assess accurately the capabilities of microorganisms and to compare microbial processes to other ecosystem parameters. These approaches have led to enormous advances in understanding microbial food webs. Reconciling our expanding knowledge with general questions about the significance and representation of microbial food webs in ecosystem studies requires additional approaches including comparative studies and field experiments. Comparative studies, analyses of microbial stocks or rates across a wide range of ecosystems, lead to quantitative models of microbial processes. These models facilitate testing of hypotheses at a very general level, allow the comparison of different stocks or rate processes across a gradient of systems, and detect unusual situations or outlier systems. Field experimental manipulations offer the advantages of working with intact natural communities, of direct evaluation of results with statistical methods, and of testing important qualitative hypotheses. Both comparative and field manipulation studies have led to important advances in the study of microbial food webs and should be expanded.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04807.x
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  • 21
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    O'day, D. H. (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    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.1550-7408.1991.tb04811.x
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  • 22
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    Instructions to Contributors: (revised guidelines as of January 1991, superseding all earlier printings) (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    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.1550-7408.1991.tb04813.x
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  • 23
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    The Effects of the Methylating Agent 1,2-Bis(methylsulfonyl)-1-methylhydrazine on Morphology, DNA Content and Mitochondrial Function of Trypanosoma brucei Subspecies (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Repeated exposure of trypanosomes in vitro or in vivo to low concentrations of the methylating agent 1,2-bis(methylsulfonyl)-1-methylhydrazine induces a series of moderately synchronous morphological and biochemical changes. Cell division halts and the long-slender bloodstream forms transform to short-stumpy forms via larger intermediate-stage cells which contain approximately double the normal G2 content of DNA. In common with naturally occurring short-stumpy trypanosomes, drug-induced short-stumpy forms do not infect rodents and when transferred to Cunningham's medium, transform to and replicate as procylics. Furthermore, these short-stumpy forms exhibit α-ketoglutarate supported motility and oxygen consumption, acquire the ability to reduce nitroblue tetrazolium (NADH diaphorase positivity) and appear to be in the G1 or G0 stage of the cell cycle based upon DNA content.
    Type of Medium: Electronic Resource
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    Extracellular Calcium Concentration Affects Infectivity of Ichthyophthirius (Ciliophora) Theronts (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Tomonts and their theront offspring of the hymenostomatid fish parasite Ichthyophthirius multifiliis were exposed to calcium levels from 0 to 0.8 mM Ca2+. The survival and reproductive rates of tomonts in the absence of extracellular calcium were not significantly different from rates of tomonts provided calcium. Theronts that developed in the absence of calcium, however, were not infective for Ictalurus punctatus even when the extracellular magnesium concentration was doubled. Theronts that developed in 0.10 mM Ca2+ were infective (0.77 trophonts/mm2 of pectoral fin) to essentially the same extent as theronts provided 0.33 mM Ca2+. Infectivity of those provided 0.8 mM Ca2+ was 1.79 trophonts/mm2 of fin, similar to that of theront controls. Theronts deprived of extracellular calcium as they developed contained significantly fewer secretory mucocysts than did theronts provided 0.1 to 0.8 mM Ca2+ although no significant differences among groups occurred with respect to abundance of crystalline or differentiating mucocysts. Theronts deprived of extracellular calcium also had swollen or enlarged mitochondria and abnormal crystalline mucocysts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04426.x
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  • 25
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    Anomalous Cases of Conjugation and Spontaneous Autogamy in Stylonychia mytilus: A Note on the Asexuality of Early Conjugants (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Four types of anomalous conjugation were documented in Stylonychia mytilus. Type I pairs were formed between mates of different sizes. These pairs exhibited an abnormal site of fusion in at least one of the mates, and the mates might face each other ventrally throughout conjugation instead of the normal side-by-side position. Type I pairs underwent sexual nuclear development and proceeded with the first cortical reorganization as in normal conjugants. Type II involved pairing at the anterior ends of mates with ventral surfaces facing the same direction. These pairs also underwent sexual nuclear development. Hence, aberrant orientation of the mates, and also ectopic sites of cytoplasmic fusion, if extensive, would permit sexual development. Type III pairs were united ventral-to-ventral with their anterior-left sides at the adoral zone of membranelles, and remained as such throughout conjugation. In these pairs, nuclear and cortical events were typical of the asexual development of physiological reorganization. In Type IV pairs, one mate of the pair possessed a fission furrow and developed two sets of ciliature typical of binary fission, while the other mate might undergo physiological reorganization or binary fission. Type III and Type IV pairs thus reveal the asexual state of early conjugants, which can pursue either one of the two modes of asexual cortical reorganization; these cases reinforce the notion of overlap of asexual and sexual cycles during conjugation of hypotrichs. Spontaneous autogamy was documented for the first time for this genus. The autogamonts proceeded with nuclear development and with the first cortical reorganization. Some probably underwent second and third reorganizations, as in conjugants, but accompanied by abnormalities, particularly in the stages beyond fertilization. Post-autogamous clones were nonviable except for one dubious case.
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04429.x
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    Effects of Osmotic Pressure on the Oxidative Metabolism of Leishmania major Promastigotes (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Leishmania major promastigotes were washed and resuspended in an iso-osmotic buffer. The rate of oxidation of 14C-labeled substrates was then measured as a function of osmolality. An acute decrease in osmolality (achieved by adding H2O to the cell suspension) caused an increase in the rates of 14CO2 production from [6-14C]glucose and, to a lesser extent, from [1, (3)-14C]glycerol. An acute increase in osmolality (achieved by adding NaCl, KCl, or mannitol) strongly inhibited the rates of 14CO2 production from [1-: 14C]alanine, [1-14C]glutamate, and [1, (3)-14C]glycerol. The rates of 14CO2 formation from [1-14C]laurate, [1-14C]acetate, and [2-14C]glucose (all of which form [1-14C]acetyl CoA prior to oxidation) were also inhibited, but less strongly, by increasing osmolality. These data suggest that with increasing osmolality there is an inhibition of mitochondrial oxidative capacity, which could facilitate the increase in alanine pool size that occurs in response to hyper-osmotic stress. Similarly, an increase in oxidative capacity would help prevent a rebuild up of the alanine pool after its rapid loss to the medium in response to hypo-osmotic stress.
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04434.x
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  • 27
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    The Nuclear Genomes of Hypotrichous Ciliates: Maintaining the Maximum and the Minimum of Information (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    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.1550-7408.1991.tb04438.x
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    Enterocytozoon salmonis N. Sp.: An Intranuclear Microsporidium from Salmonid Fish (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The developmental stages of a recently described microsporidian from the nucleus of hematopoietic cells of salmonid fish were found to be unique among the Microsporida. All observed stages, including meronts, sporonts, and spores were in direct contact with the host cell nucleus (principally hematopoietic cells) of chinook salmon (Oncorhynchus tshawytscha). There is no par-asitophorous vacuole and sporogony does not involve formation of a pansporoblastic membrane as with other members of the suborder Apansporoblastina. The extrusion apparatus differentiates prior to division of sporogonial plasmodia. The spores are ovoid (1 times 2 μm) and uninucleate, and possess a coiled polar tube with 8-12 turns. Developmental stages of the salmonid microsporidian are similar to those described for Enterocytozoon bieneusi as found in the intestinal mucosa of human AIDS patients. However, the intranuclear development, different cell types, and host infected clearly separate the salmonid and human parasites. Accordingly, the intranuclear parasite of salmonids is given the name Enterocytozoon salmonis n. sp. within the suborder Apansporoblastina.
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04440.x
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  • 29
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    Pattern Formation in Mirror-Image Doublets of the Ciliate Stylonychia pustulata (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Mirror-image symmetry doublets of the ciliate Stylonychia pustulata were obtained from the progenies of dividing cells in which cell division was inhibited by heat-shocks. In two components consisting of the doublet, the left (cell's) component possessed ciliary organelles arranged in almost the same pattern as in normal singlets, while the right one had surface organelles located in a mirror-image symmetry of those of the left component. In cell division of the doublet, two sets of ciliary primordia that were arranged in a mirror-image symmetry developed synchronously in both components. In about 80% of oral primordia (OP) of the right components, the arrangement of the membranellar bands became abnormal. In some cases, OP of the right component were occasionally separated into two longitudinal halves, each consisting of normal membranelles and inverted membranelles. A set of primordia of the paroral membranelles and fronto-ventro-transverse cirri was rarely derived from the basal bodies of the right half with a band of normal membranelles. As a result, a third component with the ciliary organelles normally arranged emerged on the right side of the original right component. The differentiation of membranelles and segmentation of the primordial streaks into cim proceeded from anterior to posterior. A cytoplasmic bulge with multiple right marginal cirral rows was frequently formed at the right margin of the doublet. The behavior in the separation of third and fourth streaks from a primordial streak of dorsal cirri was not mirror-image symmetrical in each component.
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    Temperature-induced Changes in the Synthesis of Unsaturated Fatty Acids by Acanthamoeba castellanii (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Major fatty acid components of Acanthamoeba castellanii lipids extracted after growth at 30°C include myristate, palmitate, stearate and the polyunsaturates linoleate, eicosadienoate, eicosatrienoate and arachidonate, with oleate as the sole major monounsaturated fatty acid. By comparison, growth at 15°C gave increased linoleate, eicosatrienoate and arachidonate, but decreased oleate and palmitate. When the growth temperature was shifted downwards from 30°C to 15°C, increased lipid unsaturation occurred over a period of 24 h; thus decreases of oleate and eicosadienoate were accompanied by increases in linoleate, eicosatrienoate, arachidonate and eicosapentaenoate. An upwards shift from 15°C to 30°C gave negligible alterations in fatty acid composition over a similar period. At 15°C organisms rapidly use [1-14C] acetate for de novo fatty acid synthesis; stearate is converted via oleate to further desaturation and chain elongation products. Similar short term experiments at 30°C indicate only de novo synthesis and Δ9-desaturation; synthesis of polyunsaturates was a much slower process. Rapid incorporation of [1-14C] oleate at 30°C was not accompanied by metabolic conversion over two hours, whereas at 15°C n-6 desaturation to linoleate was observed. Temperature shift of organisms from 15°C to 30°C in the presence of [1-14C] acetate revealed that over half of the fatty acids in newly-synthesised lipids were saturated, but the proportions of unsaturated fatty acids increased with time until the total polyenoate components reached 17% after 22 h. A shift of temperature in the reverse direction gave a corresponding figure of 60% for polyunsaturated fatty acids. These results emphasize the importance of n-6 desaturation in the low temperature adaptation of Acanthamoeba castellanii.
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb06076.x
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    Splenomegaly and Reticulocytosis Caused by Babesia microti Infections in Natural Populations of the Montane Vole, Microtus montanus (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . A survey for Babesia microti in rodents was conducted at six sites within Grand Teton National Park, Wyoming. Blood and spleen smears, hematocrits, and reticulocyte counts were made on all of the animals to evaluate parameters for the diagnosis of babesiosis. Ticks were removed for identification. Of 257 Microtus montanus, 103 were infected with B. microti. In addition, five of 12 Microtus pennsylvanicus and one of three Arvicola richardsoni were parasitized by B. microti. Peromyscus maniculatus (n = 40) were not infected. Concurrent infections by Hepatozoon sp., Trypanosoma sp., and the bacterium, Grahamella sp., were noted in blood smears from a number of M. montanus. Splenomegaly and reticulocytosis were significant parameters associated with babesiosis while decreased hematocrit was not. Ticks removed from the voles were identified as Ixodes eastoni and were the probable vectors of the B. microti.
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    Identification of the Mitochondrial Genome in the Chrysophyte Alga Ochromonas danica (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Analysis of total DNA isolated from the Chrysophyte alga Ochromonas danica revealed, in addition to nuclear DNA, two genomes present as numerous copies per cell. The larger genome (˜120 kilobase pairs or kbp) is the plastid DNA, which is identified by its hybridization to plasmids containing sequences for the photosynthesis genes rbcL, psbA, and psbC. The smaller genome (40 kbp) is the mitochondrial genome as identified by its hybridization with plasmids containing gene sequences of plant cytochrome oxidase subunits I and II. Both the 120- and 40-kbp genomes contain genes for the small and large subunits of rDNA. The mitochondrial genome is linear with terminal inverted repeats of about 1.6 kbp. Two other morphologically similar species were examined, Ochromonas minuta and Poteriochromonas malhamensis. All three species have linear mitochondrial DNA of 40 kbp. Comparisons of endonuclease restriction-fragment patterns of the mitochondrial and chloroplast DNAs as well as those of their nuclear rDNA repeats failed to reveal any fragment shared by any two of the species. Likewise, no common fragment size was detected by hybridization with plasmids containing heterologous DNA or with total mitochondrial DNA of O. danica; these observations support the taxonomic assignment of these three organisms to different species. The Ochromonas mitochondrial genomes are the first identified in the chlorophyll a/c group of algae. Combining these results with electron microscopic observations of putative mitochondrial genomes reported for other chromophytes and published molecular studies of other algal groups suggests that all classes of eukaryote algae may have mitochondrial genomes 〈 100 kbp in size, more like other protistans than land plants.
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    Effect of Hyper-Osmotic Stress On Alanine Content of Leishmania Major Promastigotes (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Earlier studies showed that Leishmania major promastigotes are sensitive to osmotic conditions. A reduction in osmolality caused the cells to shorten and to rapidly release most of their large internal pool of alanine. In this study some effects of hyper-osmotic stress were examined. an increase in osmolality of the culture medium from 308 to 625 mOsm/kg caused only a small decrease in growth rate. When cells grown in the usual culture medium (308 mOsm/kg) were washed, resuspended in iso-osmotic buffer, and subjected to acute hyper-osmotic stress by addition of mannitol, the alanine content increased even in the absence of exogenous substrate. Promastigotes, depleted of alanine by a 5-min exposure to hypo-osmotic conditions, also synthesized alanine when resuspended in iso-osmotic buffer. Washed cells resuspended in iso-osmotic buffer consume their internal pool of alanine under aerobic conditions, Rates of consumption decreased on addition of mannitol, becoming zero at about 440 mOsm/kg. At higher osmolalities, alanine synthesis occurred. to estimate whether proteolysis could account for alanine synthesis in the absence of exogenous substrate, cells that had been grown with [1-14C]leucine were washed and resuspended under hypo-, iso-, and hyper-osmotic conditions and the amounts of 14CO2 and 14C-labelled peptides released in 1 h were measured. Little proteolysis occurred under these conditions, but the possibility that proteolysis was the source of the alanine increase, observed in response to hyper-osmotic stress, cannot be ruled out.
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    The Protozoan-Metazoan Trophic Link In Pelagic Ecosystems (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The evidence for a qualitatively and quantitatively important trophic link between planktonic Protozoa and higher order metazoan consumers is reviewed. the available data are obtained primarily, but not exclusively, from laboratory studies of calanoid copepod consumers and tintinnid ciliate prey from marine estuarine and nearshore environments. the data indicates that the protozoan-metazoan link is of similar magnitude and importance in the pelagic ecosystems of freshwaters. It is proposed that planktonic Protozoa constitute a high quality, nitrogen-rich food in the diets of their metazoan consumers. Implications of die trophic link to the consumers, prey, and ecosystem are discussed.
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04806.x
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    A Nuclear-Envelope-Specific Protein In Amoeba Proteus Detected With A Monoclonal Antibody (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A protein with two subtypes of 205 and 180 kDa was localized on the nuclear envelope of amoebae as detected by indirect immunofluorescence staining and immuno-electron microscopy using a monoclonal antibody as a probe. Electron microscopic observation showed that the protein was located on the honeycomb lamina of the nuclear envelope. During mitosis, the protein dispersed throughout the cytoplasm but reappeared on the nuclear envelope after the reformation of the envelopes of daughter nuclei. the findings suggested that the protein is a component of the nuclear lamina of amoebae.
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    Ultrastructural Study of the Development of Pleistophora schubergi Zwölfer, 1927 (Protozoa, Microsporida) in Larvae of the Spruce Budworm, Choristoneura fumiferana and Its Subsequent Taxonomic Change to the Genus Endoreticulatus (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: This study demonstrates that Pleistophora schubergi Zwölfer, 1927, a microsporidium originally isolated from the midgut epithelium of Nygmia phaeorrhoea Don (Euproctis chrysorrhoea L.) and Porthetria dispar L., and subsequently reported in several other insects including the spruce budworm, Choristoneura fumiferana (the host used in this investigation), does not belong in the genus Pleistophora Gurley, 1893. Pleistophora schubergi lacks the major features that are characteristic of Pleistophora typicalis, the type species of this genus. A comparison of ultrastructural observations reported for the type species of the genus Pleistophora, P. typicalis, and our observations of P. schubergi revealed significant differences. A thick (0.5 μm) amorphous coat, derived from parasite secretions and deposited external to the parasite plasmalemma, surrounds all developmental stages in P. typicalis. Double membranes, derived from host rough endoplasmic reticulum cisternae encircle the parasite plasmalemma of all developmental stages in P. schubergi. The sporophorous vesicle encases the spores in P. typicalis, and originates from the parasite-secreted coat that is present around meronts. In P. schubergi, the host endoplasmic reticulum cisternae form the envelope that surrounds the meronts. Moreover, the sporophorous vesicle envelope in P. typicalis persists around groups of spores, while in P. schubergi this envelope breaks easily to release the spores in the host cytoplasm. By comparing the characteristics of the microsporidium found in the spruce budworm with those of the recently created polysporous genera that sporulate within a vesicle, we found that P. schubergi does belong in the new genus Endoreticulatus Brooks et al. 1988, and consequently rename it Endoreticulatus schubergi (Zwölfer, 1927) n. comb.
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    Mixotrophic Protists In Marine and Freshwater Ecosystems (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Some protists from both marine and freshwater environments function at more than one trophic level by combining photosynthesis and panicle ingestion. Photosynthetic algae from several taxa (most commonly chrysomonads and dinoflagellates) have been reported to ingest living prey or nonliving particles, presumably obtaining part of their carbon and/or nutrients from phagocytosis. Conversely, some ciliates and sarcodines sequester chloroplasts after ingestion of algal prey. Plastid retention or “chloroplast symbiosis” by protists was first demonstrated 〈 20 years ago in a benthic foraminiferan. Although chloroplasts do not divide within these mixotrophic protists, they continue to function photosynthetically and may contribute to nutrition. Sarcodines and ciliates that harbor endosymbiotic algae could be considered mixotrophic but are not covered in detail here. the role of mixotrophy in the growth of protists and the impact of their grazing on prey populations have received increasing attention. Mixotrophic protists vary in their photosynthetic and ingestion capabilities, and thus, in the relative contribution of photosynthesis and phagotrophy to their nutrition. Abundant in both marine and freshwaters, they are potentially important predators of algae and bacteria in some systems. Mixotrophy may make a stronger link between the microbial and classic planktonic food webs by increasing trophic efficiency.
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04805.x
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    Frankel, J. (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04810.x
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    Costal Strip Accumulation and Lorica Assembly In the Marine Choanoflagellate Diplotheca Costata Valkanov (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The lorica of the tectiform choanoflagellate D. costata contains five categories of costal strips distinguishable from each other on the basis of morphology and patterning. Categories of strips include those forming the anterior transverse costa; the anterior, intermediate, and posterior costal strips, respectively, of the longitudinal costae and those constituting the posterior transverse costa. the distinctive morphology of each class of strips makes it possible to observe their location and orientation within the overall accumulation of strips at the top of the parent cell collar. In Diplotheca costata the orientation and positioning of the different categories of strips in an accumulation anticipates their orientation and imbrication in the mature lorica. Assembly of the lorica from an accumulation of strips involves lateral sliding of costal strips to constitute transverse costae and longitudinal sliding of strips to constitute longitudinal costae. the motive force for lorica assembly is provided by extension of the anterolateral tentacles.
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    Green, J. C., Leadbeater, B. S. C. & Diver, W. L. (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04812.x
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    On the Cytology of Toxoglugea chironomi (Debaisieux, 1931) Jírovec 1936 (Microspora, Thelohaniidae) (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . The light microscopic and ultrastructural characteristics of a microsporidium provisionally identified as Toxoglugea chironomi (Debaiseux, 1931) Jírovec, 1936, is described. It was isolated from oenocytes and adipose tissue of a midge larva of the genus Dicrotendipes. Merozoites are diplokaryotic. The sporogony produces, by fragmentation, eight monokaryotic spores in a sporophorous vesicle. Mature spores are horse-shoe shaped. The total length is about 5.8 μm, the width 0.8-0.9 μm, the external height of the curve 2.3-3.5 μm, and the external width of the curve 3.5-5.2 μm. The polaroplast has lamellar compartments of two types: narrow and closely packed anteriorly, and wider and more loosely arranged posteriorly. The isofilar polar filament is arranged in 8–10 coils in the posterior fourth of the spore. The external nuclear membrane is sometimes continuous with the endoplasmic reticulum. Lamellar and tubular material of exospore construction are present in the episporontal space from the beginning of sporogony. Teratological and normal spores sometimes occur together in the sporophorous vesicle. The identification of the species is discussed and the ultrastructure is compared to Toxoglugea variabilis, the only further species of the genus with known ultrastructural cytology.
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    The Response of Contractile and Non-Contractile Vacuoles of Paramecium calkinsi to Widely Varying Salinities (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Paramecium calkinsi from tidal marshes survive a wide salinity range. Fluid output of contractile vacuoles of these cells decreased as salinity of the medium to which they were acclimated increased, and both pulse rate and vacuole volume were used to regulate output. When cells were first exposed to more dilute medium, contractile vacuoles greatly increased volume so that fluid output increased even though pulse rate decreased. In cells shifted to a more concentrated medium, contractile vacuole output decreased by decreasing pulse rate. The contractile vacuole is surrounded by a set of collecting structures which change form as the salinity changes. Distensible ampullae are found in media of low salinity and collecting canals are found in media of high salinity. When cells are shifted from high salinity to low, the number of ampullae increases and the number of canals decreases. When cells are shifted from low salinity to high, the number of ampullae decreases and the number of canals decreases. Other non-contracting vacuoles also appear in response to a hypoosmotic shock. These include vacuoles within the cell as well as “blisters” on the surface. The number and frequency of blisters increases with the size of the hypoosmotic shock. They detach from cells without resulting in any visible loss of cytoplasm. Non-contractile vacuoles may play a role in sequestering and removing excess water that the contractile vacuoles cannot handle.
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    Cosmetophilus vonones, N. G., N. Sp., (Apicomplexa: Actinocephalidae) in the Harvestman Vonones sayi (Arachnida: Cosmetidae) (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The gregarine Cosmetophilus vonones, n. g., n. sp. (Sporozoasida: Actinocephalidae: Acanthosporinae) from the intestine and intestinal caeca of the harvestman Vonones sayi (Simon) (Opiliones: Cosmetidae) is described. The new internal parasite is the first recorded from a harvestman in the New World and the second from the opilion suborder Laniatores. In addition to the records from the type locality in western Texas, additional collections are reported from the same host in central and eastern Texas and Tennessee.
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    Infraciliature, Morphogenesis and Life Cycle of Endosphaera terebrans (Suctoria, Tokophridae) (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The morphology, infraciliature, and life cycle of Endosphaera terebrans, a suctorian endocommensal of peritrichs, have been studied with the aid of silver impregnation.The life cycle of Endosphaera terebrans begins with infection of the host cell by a small larva. The swarmer has a pointed needle-like cellular projection and two rings of cilia. The swarmer penetrates the peritrich, loses the cilia, and then matures into an adult. The infraciliature of the adult form has four rows of barren kinetosomes that lack kinetodesmal fibers. By endogenous budding, a migratory larva is produced that leaves the host cell through the peristomial disc and that can infect other peritrichs.
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    Axenic Cultivation of the Anaerobic Free-Living Ciliate Trimyema compressum (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The strain N of Trimyema compressum, an anaerobic free-living ciliate, was cultivated axenically in a medium containing a buffered salt solution, yeast extract, trypticase, and glutathione. Dead bacteria were indispensable as food; a culture of the ciliate together with heat-killed Klebsiella pneumoniae has been established for more than one year. In the medium described, the ciliates grow to a higher cell density than in cultures with living bacteria as food. During the process of axenization, a nonmethanogenic bacterial endosymbiont was lost. In the microbodies of T. compressum, hydrogenase could be localized by the technique of indirect immunofluorescence.
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    Fine Structure of a New Human Microsporidian, Encephalitozoon hellem, in Culture (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Encephalitozoon hellem is a new human microsporidian isolated from corneal biopsies and conjunctival scrapings of three AIDS patients and cultured in Madin Darby canine kidney (MDCK) cells. Encephalitozoon hellem and Encephalitozoon cuniculi display different protein profiles with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and unique antibody binding patterns with murine antisera against Western blots of each organism. Developmental stages of E. hellem in culture are similar to E. cuniculi. Meronts are 1.3–2.7 μm in diameter, develop within a parasitophorous vacuole adjacent to the vacuolar membrane, divide by binary fission, and contain one or two discrete nuclei. Sporonts measure 2 × 3 μm, separate from the vacuolar membrane, and have a thickened outer membrane. Sporoblasts display a tri-layered wall and possess the earliest recognized polar filaments. Mature spores measure 1 × 1.5 μm and are more electron-dense than other stages. Each spore contains a single nucleus, a polar tubule with four to nine coils, thin electron-dense exospore and thick, electron-lucent endospore. Although E. hellem and E. cuniculi differ biochemically and immunologically, their fine structure and development are indistinguishable.
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    Nocodazole-Resistant Mutants in Paramecium (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effect of the microtubule inhibitor nocodazole was studied on Paramecium and shown to arrest cell multiplication, depolymerize the internal microtubule network, and block the development of macro- and micronuclear spindles and of the cytospindle (a cortical microtubule array assembled during division). After ultraviolet mutagenesis, three mutants resistant to nocodazole, that is capable of continued growth in the presence of the drug, were isolated and shown to correspond to three nonallelic single-gene nuclear mutations. One (nocr-1) is semidominant while the other two (nocr-2 and nocr-3) are recessive. Cytological and physiological studies of nocodazole's effects on the mutants demonstrate that their resistance is due neither to a lack of drug penetration nor to its degradation since, in each mutant in the presence of the drug, some microtubule networks are normal or subnormal while others remain affected as in wild-type cells. These are the first mutants resistant to microtubule depolymerizing drugs obtained in ciliates that provide a new tool for studying the assembly and dynamics of the diverse microtubule arrays in this type of organism.
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    Distribution of Carbohydrates Recognized by the Lectins Euonymus europaeus and Concanavalin A in Monoxenic and Heteroxenic Trypanosomatids (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We observed a wide distribution of the carbohydrate epitopes galactosylα(1–3) galactose (galα1–3 gal), α-glucoside, and α-mannoside in mono- and heteroxenic trypanosomatids by using fluorescein-labelled lectins of Euonymus europaeus (EE) and Concanavalin A (Con A) as well as sera from acute chagasic patients who have very high levels of anti-galα(1–3) gal antibodies. The direct fluorescence test for galα1–3 gal with EE was positive at minimum concentrations of 6 μg/ml for heteroxenic trypanosomatids and 0.7 μg/ml for monoxenic ones and for the plant parasite, Phytomonas. On the other hand, heteroxenic trypanosomatids that infect vertebrates bound ten-fold more Con A than monoxenic flagellates and Phytomonas. These data were confirmed in ELISA and Western Blot assays carried out with peroxidase-labelled EE and Con A. Euonymus europaeus recognized several glycoproteins in all trypanosomatids that we tested. Con A, however, recognized a glycoprotein cluster in heteroxenic protozoa, which ranging from 60–120 kDa, seemed to lack monoxenic parasites and Phytomonas. These findings suggest that α-D-mannose and α-D-glucose might play an important role in the interaction between trypanosomatids and vertebrate hosts.
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    Cortical and Nuclear Events During Cell Division and Resting Cyst Formation in Colpoda inflata (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Nuclear and cortical phenomena during dividing and resting cyst formation of Colpoda inflata are described. Cell division forms a cyst and produces two or four tomites. In each tomite, the right oral field results from the proliferation of the anterior extreme of a single kinety, and the left oral field results from the proliferation of four, five, or six somatic kineties. After macronuclear division, each macronuclear mass undergoes a chromatinic extrusion process. During resting cyst formation, the oral infraciliature of the vegetative cell is resorbed. The somatic kineties dispose in a radial way and some pairs of kinetosomes disappear. As in cell division, there is an extrusion process. From these results we conclude that the resting cysts of Colpoda inflata cannot be included in any group of the previous classifications for hypotrich resting cysts. Thus, we propose a new additional group to Walker and Maugel's classification called PKR (partial-kinetosome-resorbing) cysts.
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    Purification and Substrate Specificity of Two Cysteine Proteinases of Giardia lamblia (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The proteinase activity present in homogenates of trophozoites of Giardia lamblia, active on azocasein and urea-denaturated hemoglobin, was separated into two different enzymes by a series of purification procedures. These procedures included gel filtration on Fractogel TSK HW-55 (F), organomercurial agarose affinity chromatography, and ion exchange chromatography on DEAE-cellulose. By chromatography on Sephadex G-100, two purified enzymes exhibited relative molecular weights of Mr= 95,000 and 35,000 ± 10%, respectively. On the basis of inhibition by thiol reagents and abrogation of this effect by dithiothreitol and cysteine, they were identified as cysteine proteinases. Proteinase I (Mr= 95,000) and proteinase II (Mr= 35,000) were active against the β-chain of insulin releasing characteristic fragments. However, differences in substrate specificities of the two enzymes could be observed by using synthetic peptides that represent sequences 1–6, 8–18, and 20–30 of the insulin β-chain. Furthermore, the synthetic tetrapeptides Arg-Gly-Phe-Phe, Arg-Gly-Leu-Hyp, and Arg-Arg-Phe-Phe were hydrolyzed by the two proteinases releasing Phe-Phe and Leu-Hyp, respectively. Compared with Arg-Gly-Phe-Phe, the rates of hydrolysis of Arg-Gly-Leu-Hyp and Arg-Arg-Phe-Phe at substrate concentrations of 1 mM were 91% and 63% (proteinase I) and 80% and 57% (proteinase II), respectively.
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    Three-Dimensional Reconstruction of Rabbit-Derived Pneumocystis carinii from Serial-Thin Sections II: Intermediate Precyst (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Three-dimensional reconstruction of a binucleate intermediate precyst of Pneumocystis carinii was performed from serial-thin sections using the CATIA (Conception Assistée Tridimensionnelle Inter Active) Dassault system program. The presence of a mitochondrion, complex well-developed endoplasmic structures, and numerous Golgi vesicles was established. A better understanding of the ultrastructure of rabbit-derived P. carinii stages made it possible to formulate hypotheses on the evolution and physiology of the endomembrane system. Thus, the presence of the well-developed endoplasmic saccular structure and more than 230 Golgi vesicles in its vicinity might be implicated in the differentiation of the parasite surface structures and might also be related to nuclear division and individualization of intracystic bodies.
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    BOOK REVIEWS (1991)
    Oxford, UK : Blackwell Publishing Ltd
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    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Brusca, R. C. & Brusca, G. J. 1990. Invertebrates. Sinauer, Sunderland, MassachusettsMiller, H. R. P. (ed.) 1990. Immunity to and Diagnosis of Internal Parasitism. Vol. 9, no. 2. Revue Scientifiqueet Technique, Ofie International Des Epizootics. Office International Des Epizootics, Paris, France.Preston, T. M., King, C. A. & Hyams, J. S. 1990. The Cytoskeleton and Cell Motility. Chapman and Hall, New York, New York.
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    IN MEMORIAM W. MALCOLM REID (1910-1990) (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    Society of Protozoologists 43rd Annual Meeting (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
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    Morphology, Morphogenesis and Systematic Position of the Sorocarp Forming Ciliate Sorogena Stoianovitchae Bradbury & Olive, 1980 (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    Notes: Reinvestigation of the type population of the sorocarp-forming ciliate Sorogena stoianovitchae Bradbury & Olive, 1980 using the Fernández-Galiano technique and various electron-microscopy techniques (scanning electron microscopy, freeze-fracture and ultrathin sections) expands the observations reported in the original description of the species, Sorogena stoianovitchae is a colpodid ciliate with oral ciliature consisting of 25 ciliated paroral dikinetids on the right and 3-5 small adoral organelles on the left of an elongated and domed oral slit, resembling that of the genus Platyophrya. Sorogena stoianovitchae divides in the free swimming condition and not in a division cyst, as is the case in the colpodids sensu stricto (s. str.), e.g. Colpoda, Bresslaua. or Tillina, As shown in a detailed light-microscopy study, morphogenesis in S. stoianovitchae is of the stomatic mode typical for certain colpodid ciliates. Based on the wealth of new information the phylogenetic position of S. stoianovitchae is discussed at some length and arguments are given in favor of the following classifications: S. stoianovitchae Bradbury & Olive, 1980 currently sole member of the family Sorogenidae Bradbury & Olive, 1980; order Sorogenida Foissner, 1985;subclassColpodiaFoissner, 1985; class Colpodea Small & Lynn, 1981. This investigation facilitates the discovery of further members of this genus reported primarily from the tropical and subtropical zone.
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    Observations with Hoechst Staining of Amitosis in Acanthamoeba castellanii (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    Topics: Biology
    Notes: DNA staining with Hoechst 33258 allows us to visualize and to characterize amitotic division of Acanthamoeba castellanii in which the cell nucleus divides without DNA condensation and regular segregation of chromosomes. Amitosis involves several programmed and coordinated steps that exclude accidental cutting of the cell nucleus.
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    The Putative Mitochondrial Genome of Plasmodium falciparum (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    Topics: Biology
    Notes: Intraerythrocytic stages of mammalian malarial parasites employ glycolysis for energy production but some aspects of mitochondrial function appear crucial to their survival since inhibitors of mitochondrial protein synthesis and electron transport have antimalarial effects. Investigations of the putative mitochondrial genome of Plasmodium falciparum have detected organellar rRNAs and tRNAs encoded by a 35 kb circular DNA. Some features of the organization and sequence of the rRNA genes are reminiscent of chloroplast DNAs. The 35 kb DNA also encodes open reading frames for proteins normally found in chloroplast but not mitochondrial genomes. An apparently unrelated 6 kb tandemly repeated element which encodes two mitochondrial protein coding genes and fragments of rRNA genes is also found in malarial parasites. The malarial mitochondrial genome thus appears quite unusual. Further investigations are expected to provide insights into the possible functional relationships between these molecules and perhaps their evolutionary history.
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    The Fine Structure of Secretion in Hyalophysa chattoni: Formation of the Attachment Peduncle and the Chitinous Phoretic Cyst Wall (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    Notes: . The settling tomite stage of the apostome Hyalophysa chattoni secretes a phoretic cyst wall composed of chitin, mucopolysaccharides, and protein. Within 1 1/2 h after settling, an electron-dense proteinaceous cyst layer (the outer layer) is formed from secretions originating at the base of the kineties and from the thick pellicular layer between the kineties. The inner cyst layer, composed primarily of chitin (acidic and neutral polysaccharides are also present), is secreted across the entire cell surface. Cyst wall formation is completed within 6 h. The fine structure of endocyst secretion resembles stages in the secretion of chitin by fungi, yeasts, and arthropods. A proteinaceous attachment peduncle is secreted to anchor the cell to a shrimp host and is formed by the release of electron-dense secretory bodies from the cell's ventral surface.
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    Book Review (1991)
    Oxford, UK : Blackwell Publishing Ltd
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    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
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    Evidence for Regular Sporulation by Haplosporidium nelsoni (MSX) (Ascetospora; Haplosporidiidae) in Spat of the American Oyster, Crassostrea virginica (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    Notes: The spore stage of Haplosporidium nelsoni, the ascetosporan parasite causing multinucleated sphere unknown (MSX) disease in oysters, Crassostrea virginica, has been reported so rarely (≥0.01% of infected oysters) that a second host has been postulated. However, recent intensive sampling of young (≥1 year) oysters in Delaware Bay, U.S. suggests that spore formation occurs regularly in this group and that spores are produced in at least 75–85% of all infections reaching the advanced stage. Sporulation was seasonal, occurring over two to three weeks in late June/early July and again in late summer/early fall. Our data indicate that sporulation by H. nelsoni in oysters is more common than previously suspected, occurring in a segment of the host population that may not have been sufficiently sampled in the past, and that a direct life cycle should be reconsidered.
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    Further Observations on Cryptobia dahli (Mastigophorea: Kinetoplastida) Parasitizing Marine Fish (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    Notes: Studies were conducted primarily to ascertain the mode of transmission of Cryptobia dahli parasitizing the digestive tract of lumpfish (Cyclopterus lumpus). Another flagellate, morphologically similar to C. dahli, was also observed in the gut of a deepsea fish (Macrourus berglax). Several invertebrates, which are food for lumpfish, were examined for flagellates, but were neither infected nor showed evidence of cystic stages. Parasites were more abundant in the stomach, especially at about pH 5, than in other areas of the digestive tract. Transmission was achieved by pipetting the parasites into the stomach of uninfected fish, by feeding food contaminated with flagellates, and also by holding infected and uninfected fish in the same aquarium. In nature, lumpfish probably acquire parasites during winter when they aggregate and regurgitate into seawater because parasites can survive for short periods outside their host.
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    Involvement of 14-nm Filament-Forming Protein and Tubulin in Gametic Pronuclear Behavior during Conjugation in Tetrahymena (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    Notes: We have studied in detail the immunofluorescence localizations of Tetrahymena 14-nm filament-forming protein (49-kDa protein) in relation to tubulin in conjugating wild-type Tetrahymena thermophila (B strain) pairs and in pairs between B strain and star strains with defective micronuclei. The results suggest that germ nuclear behavior during conjugation may involve the following cytoskeletal structures: (1) during meiosis, microtubule structures are involved in micronuclear elongation and meiotic division; (2) at the postmeiotic stage, 49-kDa protein network structures that are formed independently of the existence of pronuclei are involved in the selection and the survival of one of four meiotic products; (3) during the third prezygotic division, gametic pronuclear transfer, and zygote formation, a cytoskeletal structure in which the 49-kDa protein colocalizes with microtubules and which is dependent on the existence of a normal gametic pronucleus is involved in gametic pronuclear behavior, and (4) during the postzygotic divisions, the microtubules are involved in nuclear behavior.
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    On the Cytology and Fine Structure of the Neogregarine Syncystis aeshnae Tuzet and Manier, 1953 (Apicomplexa, Syncystidae) (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    Topics: Biology
    Notes: The neogregarine Syncystis aeshnae Tuzet and Manier, 1953, was obtained from two species of dragonfly larvae, Aeshna grandis and Libellula quadrimaculata, collected in southern Sweden. Merogony, gamogony, and sporogony were observed in the adipose tissue, which was destroyed, and the haemocoele. Merozoites had a traditional apical complex. Gamonts associated in pairs did not unite conoid-to-conoid, and the border between gamonts was not found to break down. Each association produced 32 spores in bilobed gametocysts. Spores were elongate, oval, 4.0–5.8 × 8.0–10.0 μm in fixed and stained condition, each with 4+4 terminal and four equatorial thread-like projections. The thick-walled spore is considered the sporocyst. Species identification, ultrastructural cytology, and problems associated with using the terms “oocyst” and “sporocyst” are discussed.
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    Malaria Sporozoites Release Circumsporozoite Protein from Their Apical End and Translocate It along Their Surface (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Plasmodium sporozoites, the causative agents of malaria, release circumsporozoite (CS) protein into medium when under conditions simulating those that the parasites encounter in the bloodstream of the vertebrate host. CS protein of the rodent parasite, Plasmodium berghei, is released as the lower molecular weight form, Pb44. This release is substratum- and antibody-independent. Previous studies show that CS protein is released at the trailing, posterior end of motile sporozoites. Video and electron microscopic studies now demonstrate that CS protein is released at the apical end of cytochalasin b-immobilized sporozoites. We propose that CS protein released from the apical end, the leading end of gliding sporozoites, adheres to the sporozoite surface and is translocated posteriorly by a cytochalasin-sensitive and apparently actin-mediated surface motor, which drives gliding motility. This model explains the mechanism of both the circumsporozoite precipitation (CSP) reaction and formation of the CS protein trail by gliding sporozoites.
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb01379.x
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    IN MEMORIAM: TCHANG TSO-RUN (1900–1991) (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    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.1550-7408.1991.tb01384.x
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    Commitment to the First Cortical Reorganization During Conjugation in Stylonychia mytilus: An Argument for Homology with Cortical Development During Binary Fission (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The asexual nature of the first cortical reorganization of conjugation in Stylonychia was analyzed by comparing the effect of amputation performed at different stages of early conjugation to that performed on vegetative cells at different stages of the cell cycle. Amputation of vegetative cells delineated a point of commitment to binary fission at 0.51–0.57 of the cell cycle. Cells amputated before this point were induced to undergo the regenerative mode of asexual development, but those amputated after this point continued with binary fission. In parallel, during conjugation a similar commitment was made around the time of formation of tight mating-pairs: early conjugants amputated around this time might undergo regeneration, and those operated on after this stage continued with the first cortical reorganization as in typical conjugants. The two mates of a pair might differ in their response to amputation, suggesting that the timing of commitment to the first cortical reorganization is not related to the events of conjugation, but rather is individually determined in the vegetative cycle of the cells before they pair up in mating. These observations provide support for the notion that the first cortical reorganization of conjugants is homologous to the asexual mode of cortical development in dividers, according to the theory of developmental heterochrony in the sexual reproduction of hypotrichs. The timing of commitment to the first cortical reorganization was found to temporally correlate with the entrance of the micronuclei into meiosis. Since the first cortical reorganization can proceed without the micronucleus, this raises the possibility that initiation of micronuclear meiosis is closely coupled with, and may be determined by, the commitment to the first cortical reorganization.
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    A Test for Genetic Exchange in Mixed Infections of Leishmania major in the Sand Fly Phlebotomus papatasi (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We tested if genetic exchange was observable between two strains of Leishmania major (Trypanosomatidae) during mixed infection of the sand fly Phlebotomus papatasi. Previous studies suggested that genetic exchange may occur in natural populations of Leishmania at a low frequency, but experimental crosses examining small numbers of progeny (〈60) did not reveal hybrid parasites. Accordingly, a strategy was devised to increase the number of progeny that could be screened by 100-fold. Clonal derivatives from two strains that were infective to flies and contained numerous restriction fragment length polymorphisms were characterized and selected for resistance to methotrexate or tunicamycin by gene amplification. A successfully mixed infection of P. papatasi was obtained, and a method was developed for directly plating promastigotes from the gut contents of infected flies onto selective media. Twenty-five hundred independent progeny were scored for the presence of both drug resistance markers. No hybrid parasites were observed, indicating that the frequency of genetic exchange in this cross must be less than 4 times 10-4. The lines and methods established in this work may prove useful in future studies of the mechanism and frequency of gene exchange in Leishmania.
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    Copy Number Control in the Tetrahymena Macronuclear Genome (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    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.1550-7408.1991.tb04439.x
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    The Contribution of Ciliated Protozoa to Zooplankton Biomass in an Acidic, Subtropical Lake (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Ciliated protozoa accounted for up to 50% of the mean daily zooplankton biomass in McCloud Lake, a small (5 ha), oligotrophic, acidic (pH 4.7) lake in north-central Florida. Food resources (algae and bacterioplankton) were limiting for crustacean and rotifer zooplankton during much of the year. Myxotrophic ciliates were a dominant component of the planktonic food web. Stentor niger, an uncommon species in the plankton of lakes, dominated the ciliate assemblage and usually comprised 〉90% of total ciliate biomass. Stentor niger always contained high densities of photosynthetic zoochlorellae and contributed an estimated 30% to the total autotrophic biomass.
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    Identification and Properties of Plateins, Major Proteins in the Cortical Alveolar Plates of Euplotes (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Morphogenesis of the ciliate cortex has been viewed as an attractive model system for studying the mechanisms behind the ordered assembly of subcellular structure. Based on the assumption that identifying protein components of the cortex would facilitate the study of cortical assembly, I have produced a number of monoclonal antibodies directed against components of the cortex of Euplotes aediculatus. Several of these antibodies react with the proteins comprising the alveolar plates. These thin polygonal scales, each enclosed within a flattened membranous sac (alveolus) just beneath the cell membrane, tightly abut in a confluent monolayer that appears to lend form and rigidity to the Euplotes cell cortex. Reactivity and specificity of these monoclonal antibodies for the alveolar plates was shown by immunofluorescence staining of whole-cell preparations and of cryosections, and by immuno-gold staining of thin sections by electron microscopy. On immunoblots of SDS-PAGE separated whole-cell extracts, the plate proteins are revealed as two to three closely spaced bands centered at an Mr of 97 kDa, and a larger relative at 125 kDa. Comparative peptide mapping reveals that the members of the 97-kDa protein cluster are closely related. However, the 125-kDa polypeptide varies significantly from the 97-kDa members, and hence is not likely a synthetic precursor. Because bands of these Mr values are prominent in Coomassie blue-stained gels of whole-cell extracts, and are greatly enriched in purified cortical preparations, they likely represent the major proteins comprising the alveolar plates of E. aediculatus. I have proposed the name platein for this family of proteins.
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    Sequence of a Euplotes crassus Macronuclear DNA Molecule Encoding a Protein with Homology to a Rat Form-I Phosphoinositide-specific Phospholipase C (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A 604-base pair macronuclear DNA molecule from the hypotrichous ciliate Euplotes crassus was cloned and its DNA sequence determined. The DNA sequence contains an open reading frame capable of encoding a protein 141 amino acids in length. The putative protein contains significant sequence similarity to other eukaryotic proteins, including the rat form-I phosphoinositide-specific phospholipase C.
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    Glucan Synthesis in Pneumocystis carinii (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Rat-derived Pneumocystis carinii lysed with sodium deoxycholate catalysed the incorporation of uridine diphospho-glucose into an insoluble polymer. This enzyme activity was present in both the pellet and the supernatant when the P. carinii preparations were centrifuged. The polymer whose production was catalysed by the supernatant was examined by mass spectrometry and found to be an α 1→4 glucan, which is either unbranched or has relatively few branches. Polymer formation was completely inhibited by the addition of α amyloglucohydrolase to the supernatant. Polymer formation in the pellet of deoxycholate P. carinii preparations, unlike that in the supernatant, was partially resistant to α amyloglucohydrolase. The soluble glucan synthase activity in the supernatant was stable for more than 30 h at room temperature and was approximately 50 times more active on a cell-to-cell basis than the supernatant from deoxycholate preparations of the yeast Saccharomyces cerevisae.
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    Physiological Reorganization and Post-Traumatic Regeneration in Stylonychia mytilus: Reflections on Developmental Constraints and the Evolutionary Origin of Alternative Modes of Asexual Morphogenesis (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We investigated development of cortical ciliature in Stylonychia mytilus during starvation-induced physiological reorganization, and during regeneration following amputation of the anterior part of the cell. Cortical reorganization in the two processes is generally similar. The posterior part of the adoral zone of membranelles is resorbed and replaced with newly assembled membranelles. The pre-existing set of ventral cirri and dorsal bristles is entirely resorbed and replaced with new ones. Regenerants exhibit posterior displacement of the frontal-ventral-transverse cirri primordium and the undulating membrane primordium, and recruit basal bodies from ectopic locations for the development of these ciliature. This illustrates flexibility in the initiation site of ciliary primordia, and opportunism in utilizing building blocks. Such morphogenetic versatility of hypotrichs provides the basis for the operation of a global control of pattern formation, which governs cortical reorganization in dividers, and additionally, in the absence of the prerequisites for binary fission, alternative modes of cortical development such as physiological reorganization or regeneration. These considerations suggest that the three processes are homologous and that physiological reorganization and regeneration have evolved from binary fission. In physiological reorganization and regeneration, the micro- and macronuclei reorganize to resemble that in binary fission; these nuclear events are considered evolutionary relics of the nuclear development of binary fission. Tetrahymena also exhibits such morphogenetic flexibility; stomatogenesis is under global control, so that asexual cells can replace its oral apparatus without undergoing binary fission. Paramecium, on the other hand, adopts a more rigid strategy in relying heavily on pre-existing structures for morphogenetic cues; this could have imposed constraints in the exploration of alternative modes of asexual development.
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    Evolution of Amitosis of the Ciliate Macronucleus: Gain of the Capacity to Divide (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Ciliates exhibit nuclear dimorphism, i.e. they have a germline micronucleus and a somatic macronucleus. Macronuclei are differentiated from mitotic sisters of micronuclei. The macronuclei of “higher ciliates” are polyploid and divide acentromerically (“amitotically”); they differentiate once per life cycle. By contrast, Karyorelict (KR) ciliate macronuclei are nearly diploid and cannot divide; they must differentiate at every cell cycle. Diverse lines of evidence are presented to support the hypothesis that ancestral ciliate macronuclei were incapable of division (as in living karyorelict ciliates) and that higher ciliates gained, perhaps independently more than once, the ability to divide the macronucleus. Selective pressures that could have driven the evolution and macronuclear division and two plausible step-wise pathways for the evolution of macronuclear division are proposed. These hypotheses are relevant to our understanding of amitosis mechanisms, evolution of nuclear dimorphism, and phylogenetic classification of ciliates.
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    Trypanosoma cruzi: Flow Cytometric Analysis of Developmental Stage Differences in DNA (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Flow cytometry and DNA binding-specific fluorescent reagents were used to compare the total DNA, G-C, and A-T content of the epimastigote and trypomastigote stages of Trypanosoma cruzi stocks. Significant total DNA differences of 2–12% between epimastigotes and trypomastigotes were found in three of six stocks studied. The epimastigote G-C content of five of six stocks was 4–8% higher than trypomastigotes, whereas the trypomastigote A-T content was 2.5–13% higher than the epimastigote A-T content. Although no obvious developmental stage association between total DNA and base composition was found, intrastage associations do exist. These observations were unaffected by nucleoprotein extraction implying that the observed differences between trypomastigotes and epimastigotes are not a consequence of nucleoprotein interference with DNA-binding fluorochromes. The nuclei and kinetoplasts of four T. cruzi stocks were isolated and analyzed. Developmental stage differences in nuclear and kinetoplast DNA are stock-dependent and base composition-dependent; both organelles contribute to the observed differences in DNA of intact cells. We found a nearly linear association between the percentage of total kinetoplast DNA, G-C, and A-T content. During metacyclogenesis, the G-C content decreases by approximately 7% as epimastigotes transform into metacyclic trypomastigotes. The decrease in G-C content precedes changes in morphology or in complement resistance. If the DNA changes are causally connected to developmental stage transformations in T. cruzi remains to be determined. However, our results could facilitate studies of the molecular genetic processes the parasite uses to successfully complete various phases of its life cycle and, consequently, the disease process it evokes.
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    The Enigma of the Dinoflagellate Chromosome (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
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    Gas Vacuoles and Flotation in the Testate Amoeba Arcella discoides (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The natural formation of gas vacuoles as a method of movement is described for the testate amoeba Arcella discoides. These vacuoles are used to float the organism from the substrate to the surface in an inverted position.
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    The Fine Structure of Saprodinium dentatum Lauterborn, 1908 as a Representative of the Odontostomatida (Ciliophora) (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The fine structure of the sapropelic ciliate Saprodinium dentatum is described based on phase-contrast microscopy, silver-staining techniques, cryo-fracture scanning electron microscopy, and thin sections. The study concentrates on a detailed analysis of the somatic cortex and the oral ciliature of this highly asymmetric, laterally compressed ciliate. The cell shape is dominated by a number of site-specific spines and the curving course of 10 somatic kineties (SK 1–10). The SK, composed of dikinetids, show an intrakinety differentiation that seems characteristic for other odontostomes as well. The anterior segment of the SK is mostly ciliated, followed by a non-ciliated segment in which the kinetosomes lack all typical fiber systems. Except for SK 4–6, the posterior segment is ciliated again, forming the spine kinetics associated with particular caudal spines. The anterior segment of SK 3 through SK 7 form the frontal band, which together with the two frontal kineties constitutes the main locomotory organelle for a ciliate that creeps on the substratum. A short kinety with inverse polarity, not seen in earlier light microscopical studies, was observed near the oral spine. We made particular effort to find a logical explanation for the observed association of the SK with the various caudal spines. The oral ciliature consists of nine adoral organelles located in a tripartite oral cavity. The absence of a paroral ciliature together with the position of the cytostome anterior to the adoral organelles may be the result of rotational movement of the oral apparatus during the evolution of these bizarre ciliates. Results are discussed with special reference to the phylogenetic relationship of the Odontostomatida to the Heterotrichida and no conclusive answer was found in this first electron microscopical study of an odontostomatid ciliate.
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    Differential DNA Amplification and Copy Number Control in the Hypotrichous Ciliate Euplotes crassus (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . During macronuclear development in hypotrichous ciliated protozoans, several thousand macronuclear DNA molecules are amplified several-hundred fold. We investigated the regulation of this amplification by determining the copy numbers of three different macronuclear DNA molecules in the hypotrichous ciliate Euplotes crassus. Two of the macronuclear DNA molecules were present in approximately 1,000 copies per cell, while the third was present in approximately 6,500 copies per cell. These reiteration levels were achieved either during macronuclear development, or shortly thereafter, and were maintained during vegetative growth. The most abundant macronuclear DNA molecule is present as a single-copy sequence in the micronuclear genome. Thus, its high copy number results from differential amplification. These results indicate that DNA amplification during macronuclear development is regulated individually for each macronuclear DNA molecule.
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    Life Cycle of Paramecium bursaria Syngen 1 in Nature (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Studies were completed on the natural population density of Paramecium bursaria syngen 1 and on the life cycle stages to which the individuals belonged. Green paramecia were collected from two streams once every 20 days for over one year: 413 individuals on 26 collection dates in Mikumarikyo stream and 83 individuals on 23 collection dates in Momijidani-gawa stream. Individuals in nature did not maintain at a steady density but fluctuated greatly depending on the month. It seems that conjugation occurred from April to June in the Mikumarikyo stream and from May to June in the Momijidani-gawa stream. The appearance of individuals with mating ability might be related closely to increasing population so that sexual reproduction probably occurred near the peak of the population density. The 413 individuals from Mikumarikyo stream were examined to determine their position within the life cycle; 309 (74%) were immature, 55 (13%) were adolescent, and 49 (12%) were mature. No senile individuals were observed. The fraction of individuals with mating ability was generally less than 30% at any collection. Four mating types were observed occurring with about equal frequencies in mature individuals. The results show the frequencies of the recessive genes for mating types (a and b) are higher than for dominant genes (A and B). Of 83 individuals from Momijidani-gawa stream, 44 (52%) were immature, 21 (25%) were adolescent, and 18 (21%) were mature. Again, no senile individuals were observed. Because only two mating types were found, II and III (genotypes aaB- and aabb), it seems possible that the dominant gene A was rare or absent in the Momijidani-gawa population.
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    Scandinavian Section Society of Protozoologists (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04789.x
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    Synchronous Division of an Endosymbiotic Methanogenic Bacterium In the Anaerobic Ciliate Plagiopyla Frontata Kahl (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The life cycle of a methanogenic bacterium, symbiotic within the marine, free-living anaerobic ciliate Plagiopyla frontata, was studied using light microscopy and transmission electron microscopy (TEM). the bacteria are disc-shaped. During the growth phase of the host, bacteria and hydrogenosomes (organelles which ferment pyruvate into acetate and hydrogen) are arranged in conglomerates resembling stacks of coins in which bacteria and hydrogenosomes alternate; hydrogenosomes always cap the ends of the stacks. During the growth phase, numbers of hydrogenosomes and bacteria remain constant (about 5,000 and 3,500 per cell, respectively). Hydrogenosomes increase in volume shortly after cell division. Methanogens increase in volume slowly during the growth phase of the ciliate and rapidly when the ciliate begins to divide. the hydrogenosomes divide mainly during the initial phases of cell division while the methanogens divide synchronously during the last phase of ciliate division. the timing of reproduction of the symbionts is controlled by the host-cell cycle. the ciliate is known to receive an energetic advantage from its symbionts. the suppression of continuous bacterial reproduction may trigger the secretion of excess bacterial production as soluble organic compounds, for use by the ciliate.
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    Israeli Section Society of Protozoologists (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
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    Early Development of Eimeria Papillata (Apicomplexa: Eimeriidae) In the Mouse (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Early development of Eimeria papillata (Apicomplexa) in the mouse was evaluated using Nomarski interference-contrast and brightfield microscopy. Sporozoite-shaped meronts, which were motile and contained a large posterior refractile body and a smaller anterior refractile body, were observed entering and leaving host cells in the jejunum of an experimentally infected mouse at 26 h post inoculation (HPI). However, early developmental stages were not observed in tissue of the duodenum, ileum, cecum and colon. the mean length and width of these meronts (n = 20) were 12.0 μm and 3.7 μm, respectively. Spherical or subspherical meronts containing crescent-shaped merozoites were observed at 36 HPI.
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    Structural and Functional Characterization of Paramecium Dynein: Initial Studies (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Dynein arms and isolated dynein from Paramecium tetraurelia ciliary axonemes are comparable in structure, direction of force generation, and microtubule translocation ability to other dyneins. In situ arms have dimensions and substructure similar to those of Tetrahymena. Based on spoke arrangement in intact axonemes, arms translocate axonemal microtubules in sliding such that active dynein arms are (-) end directed motors and the doublet to which the body and cape of the arms binds (N) translocates the adjacent doublet (N+1) upward. After salt extraction, based on ATPase activity, paramecium dynein is found as a 22S and a 14S species. the 22S dynein is a three-headed molecule that has unfolded from the in situ dimensions; the 14S dynein is single headed. Both dyneins can be photocleaved by UV light (350 nm) in the presence of Mg2-, ATP and vanadate; the photocleavage pattern of 22S dynein differs from that seen with Tetrahymena. Both isolated dyneins translocate taxol-stabilized, bovine brain microtubules in vitro. Under standard conditions, 22S dynein, like comparable dyneins from other organisms, translocates at velocities that are about three times faster than 14S dynein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04801.x
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    Symposium Introductory Remarks: A Brief History of Aquatic Microbial Ecology (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: This report serves to introduce the symposium on food chains and food webs that is jointly sponsored by the Society of Protozoologists and the Phycological Society of America. A brief history of the field of aquatic microbial ecology is presented with an emphasis on the development of theoretical models that have directed the course of research — research that has shaped the development of new and more complex models of the present. the paper aims to provide historical background for all symposium participants and an introduction to the specific presentations of the four guest speakers.
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04803.x
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    Biochemical and Cytological Evidence for an Overabundance of Mucocysts in the bcd Pattern Mutant of Tetrahymena thermophila (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Three acidic proteins (42 kD, 43 kD and 50 kD) were present in unusually high concentrations in cortical preparations of the Tetrahymena pattern mutant broadened cortical domains (bcd). Antisera to the 42-kD and 50-kD proteins bound to discharging mucocysts and food vacuole contents in both wild-type and mutant cells. Subsequent analysis revealed that bcd mutant cell pellicles possess five times more “docked” mucocysts than their wild-type counterparts.
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb06077.x
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    Detection and Classification of Trypanosoma cruzi by DNA Hybridization with Nonradioactive Probes (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Total or kinetoplast DNA (kDNA) from 72 isolates and clones of Trypanosoma cruzi as well as from nine related trypanosomatids were analyzed by dot hybridization using nonradioactive kDNA or cloned minicircle fragments as probes. Biotinylated-kDNA probes generated by nick-translation proved reliable for distinguishing Zymodeme 1 and Zymodeme 2bol of T. cruzi parasites. In contrast, digoxigenin-labeled kDNA obtained by random-priming did not distinguish among T. cruzi isolates but did distinguish among New World leishmanias. Cloned minicircle fragments labeled with digoxigenin gave the same results as digoxigenin-labeled kDNA, except for a 10-fold decrease in sensitivity. Digoxigenin-labeled DNA probes proved useful in unambiguously detecting T. cruzi from different geographic regions of America. However, T. rangeli and T. cruzi marinkellei were not distinguished by these probes.
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    Characterization of the Extracellular Ribonuclease of Tetrahymena pyriformis W (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Several investigations have indicated that Tetrahymena pyriformis secretes ribonuclease activity into culture media. The extracellular ribonuclease from strain W has been purified and partially characterized. The molecular weight was determined by gel filtration to be 26,500. The amino acid composition of the enzyme was compared with those of the three intracellular ribonucleases characterized by Trangas, and substantial differences were demonstrated. The extracellular enzyme hydrolyzed both polyadenylic and polyuridylic acids, indicating lack of absolute base specificity. The hydrolysis of polyadenylic acid followed normal Michaelis-Menten kinetics, but substrate inhibition occurred at high concentrations of polyuridylic acid. The hydrolysis of polyuridylic acid was competitively inhibited by 2′- and 3′-cytidine, guanine, and uridine nucleotides, and by 2′AMP. No inhibition of the hydrolysis of Torula yeast RNA was detected. The kinetic properties of the extracellular ribonuclease are compared with those of the intracellular enzymes.
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04818.x
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    Herpetomonas roitmani (Fiorini et al., 1989) N. Comb.: A Trypanosomatid with a Bacterium-like Endosymbiont in the Cytoplasm (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The trypanosomatid previously described as Crithidia roitmani is characterized here at the ultrastructural and biochemical levels. The data indicates that the parasite belongs to the Herpetomonas genus, and we therefore suggest the flagellate to be denominated as Herpetomonas roitmani n. comb. Cladistic analysis of isoenzyme data generated by eight different enzymes showed that the parasite presented a distinct banding pattern and could be grouped with some Herpetomonas spp., but not with Crithidia spp., used as reference strains. Accordingly, when the parasites were grown for longer periods in Roitman's defined medium, expontaneous differentiation from promastigotes to opisthomastigotes (typical of the Herpetomonas genus) occurred. Transmission electron microscopy revealed the presence of bacterium-like endosymbionts in the cytoplasm of all evolutive forms of the parasite. All morphological alterations characteristic of endosymbiont-bearing trypanosomatids could be observed.
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04822.x
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    Structural Alteration of the Plasma Membrane in Spores of the Microsporidium Nosema algerae on Germination (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The fine structure of the plasma membrane in spores of the microsporidium Nosema algerae, a pathogen of mosquitoes, was examined in the resting condition and after the spores were stimulated to germinate in vitro. Slow penetration of resin caused collapse of the germinated spores. Thin sections of germinated spores showed peculiar membrane infoldings that were never found in ungerminated samples. Analogous germination-dependent configurations of the plasma membrane were observed in freeze-fractured preparations of spores either fixed and impregnated with glycerol prior to freezing, or rapidly frozen with liquid propane while in the process of germination. In every case, the replicas presented germinated spores with indentations in the protoplasmic face of the plasma membrane, and apparently complementary blunt spines on the external face, that were absent in ungerminated spores. It suggests that these alterations of the plasma membrane result from a structural adjustment to a spontaneous contraction of the spore case after germination. We discuss this interpretation with regard to conflicting views on the nature of such morphological features.
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04826.x
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    PCR Amplification of Tetrahymena rDNA Segments Starting with Individual Cells (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: To facilitate studies of rDNA molecular genetics in Tetrahymena thermophila, we attempted the detection of polymorphisms in the nontranscribed spacers (NTSs) using polymerase chain reaction (PCR), starting with minute amounts of DNA. The targeted polymorphic regions are 85% adenine-thymine (AT). We found conditions of efficient and specific in vitro amplification of targeted segments in the replication domain of the 5′NTS and in the subtelomeric segment of the 3′NTS. The identity of the amplified segments was confirmed by restriction enzyme digestion and DNA sequence analysis. Digestion of the template DNA at restriction sites upstream and downstream of the targeted region increased the efficiency of amplification, presumably because the targeted segments are in a palindromic molecule. Starting from total cell DNA corresponding to as little as 0.03 picogram (equivalent to the DNA content of 0.003 cells or about 30 rDNA molecules), we observed the amplified band after agarose gel electrophoresis and ethidium bromide staining. The yield indicated more than 10-billion-fold amplification. Amplification of the subtelomeric fragment yielded homogeneous product of minimum possible length even though the telomeric-specific primer can bind, at least initially, at a multiplicity of GGGGTT repeats. Amplified 5′NTS product also was detected in an ethidium-bromide-stained gel when PCR was started with a single cell.
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb01364.x
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    Localization of Thermoreceptor Systems that Induce Step-Up and Step-Down Thermophobic Responses and Switching in the Dominance of These Systems in Blepharisma (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The distribution of thermoreceptor systems that initiate step-up and step-down thermophobic responses in bisected cells of Blepharisma was examined. Anterior cell fragments responded by ciliary reversal to a step-down in temperature and by repression of spontaneous ciliary reversal to a step-up. Posterior fragments responded by ciliary reversal to a step-up in thermal stimulation and by repression of spontaneous ciliary reversal in response to step-down stimulation. Results indicate that two kinds of thermoreceptor systems exist in the anterior half of each cell; one is responsible for ciliary reversal induced by step-down stimulation, and the other is responsible for repression of the ciliary reversal caused by step-up thermal stimulation. Likewise, there are also two kinds of thermoreceptor systems in the posterior half of the cell; one is responsible for ciliary reversal in response to a step-up in temperature, and the other is responsible for the repression of ciliary reversal on a step-down in thermal stimulation. Below about 27°C, intact cells showed ciliary reversal only when a step-down in thermal stimulation occurred, while above about 27°C cells only responded to a step-up in thermal stimulation. At about 27°C there was a switch in the dominant response from the anterior to the posterior half of an individual cell.
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    Revision of the Family Lagenophryidae Bütschli, 1889 and Description of the Family Usconophryidae N. Fam. (Ciliophora, Peritricha) (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Ten species of lagenophryid peritrichs in three genera are redescribed or described for the first time. Based on this information, the family Lagenophryidae was found to consist of five genera: Lagenophrys, Paralagenophrys, Clistolagenophrys n. g., Setonophrys, and Operculigera. Lagenophryid genera differ in gross structure of the lorica aperture and the peristomial sphincter associated with it. Shape of the lorica and mode of attachment to the host are not generic characteristics in the Lagenophryidae. Differences in shape evolved within each of the three largest lagenophryid genera merely as adaptations for attachment to different parts of a host. Usconophrys, formerly in the Lagenophryidae, and Cyclodonta are assigned to the family Usconophryidae n. fam., which is characterized by possession of a lorica, lack of a closure apparatus operated by the peristomial sphincter, and possession of an operculariform peristome. Lagenophrys, Setonophrys, and Paralagenophrys appear to have evolved separately and convergently from ancestors within Operculigera. Lagenophryid lorica apertures consisting of opposing lips probably evolved as tight seals to prevent water loss when the host is temporarily out of water. The greater diversity and wider distribution of Lagenophrys compared with other lagenophryid genera may result from an advantage in recolonizing hosts conferred by second-type division.
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    Three-Dimensional Reconstruction of Rabbit-Derived Pneumocystis carinii from Serial-Thin Sections I: Trophozoite (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The highly complex ultrastructural morphology of the endomembrane system in Pneumocystis carinii led us to perform three-dimensional reconstruction from serial-thin sections using the CATIA (Conception Assistée Tridimensionnelle Inter Active) Dassault system program. The three-dimensional reconstruction of a small trophozoite made it possible to better understand the morphological relationship among organelles and to suggest cytophysiological hypotheses. By reconstructing other parasite stages, we gathered information about the evolution of organelles during the life cycle and about their physiology.
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb01377.x
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    In Vitro Production of Lysine from 2,2′-Diaminopimelic Acid by Rumen Protozoa (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Rumen protozoa can produce lysine from free 2,2′-diaminopimelic acid (DAP). However, the quantitative importance of this transformation has been disputed; lysine contents of protozoal incubation supernatants reported by Onodera & Kandatsu [12] and Masson & Ling [9] show a 26-fold difference. The in vitro experimental methods of both groups were compared to determine the causes of this difference. Lysine production was proportional to DAP concentration. Results with rumen protozoa from sheep or goats were similar. The incubation medium and deproteinizing procedure of the Welsh group gave a two-fold increase in lysine production compared with Japanese protocols. Omissions of rice starch from protozoal incubations slightly increased lysine production, whereas omissions of antibacterial agents resulted in varying, yet relatively small changes. The greatest cause of the difference was the number of rumen protozoa incubated. When this factor was taken into account, the difference in the maximum rates of lysine production between the Welsh and Japanese groups was only three-fold, namely 4.5 versus 15.0 nmol lysine/105 protozoa/h. Adding other amino acids to the incubations suggested that DAP uptake by rumen protozoa may occur via transport system ASC. The importance of DAP metabolism by protozoa as a source of lysine for ruminant host animals is discussed.
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    Book Reviews (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    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.1550-7408.1991.tb01383.x
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    A Serum-free, Partly Defined Medium, PDM-805, for Axenic Cultivation of Entamoeba histolytica Schaudinn, 1903 and other Entamoeba (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We describe the first serum-free, partly defined medium (PDM-805) for cultivating the human enteric pathogen, Entamoeba histolytica, and the reptilian amebae E. barreti, E. invadens, and E. terrapinae. PDM-805 was developed by the stepwise replacement of yeast extract, bovine serum, and a casein peptone digest in TYI-S-33, a medium widely used for the axenic cultivation of these parasites. The defined components include amino acids, carbohydrates, B vitamins, ascorbic acid, tocopherol, thioctic acid, nucleic acid precursors, trace metals, and phosphate buffers. The undefined components include a highly purified bovine serum albumin, a lipoprotein-cholesterol solution from bovine serum, and a dialyzable, autoclavable, water-soluble growth factor(s) having a molecular weight of less than 3,500 prepared from casein peptone. To date, studies on the growth requirements of E. histolytica, strain 200:NIH, show the following are essential for sustained multiplication of this ameba: iron, glucose, biotin, folic acid, niacinamide, pantothenate, pyridoxal, riboflavin, thiamine, cysteine, an ammonium moiety (in addition to that present in cysteine), bovine serum albumin, lipoprotein-cholesterol, and casein peptone dialysate.
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    BOOK REVIEW (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
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    URL: http://dx.doi.org/10.1111/j.1550-7408.1991.tb04444.x
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    Nutritional Requirements of Blastocrithidia culicis, a Trypanosomatid with an Endosymbiont (1991)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
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    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . The symbiont-containing Blastocrithidia culicis from Aedes vexans, unlike most lower trypanosomatids cultivated in defined media, require only three amino acids: methionine, histidine, and arginine; only three vitamins: thiamin, nicotinamide, and riboflavin; and neither heme nor purine. The bacterium-like endosymbiont presumably provides the trypanosomatid's other essential nutrients.
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