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the effects of some factors on the growth and morphology of naegleria sp. and three strains of the genus acanthamoeba.the effects of various biophysical and chemical factors on the cytology of vegetative stages of naegleria sp., vitek strain, acanthamoeba culbertsoni, acanthamoeba castellanii, neff strain and acanthamoeba polyphaga, no. 1289, were studied. the amoebae were cultured in a liquid medium under axenic conditions. the optimum temperature was 37 degrees c for pathogenic strains of naegleria sp. and acanthamoeba culbertsoni and 20 degrees c for a. castellanii. no changes were observed in the growth of ...19754366
glucolipid synthesis in acanthamoeba castellanii. 197612367
the cellulase enzyme system during growth and development of acanthamoeba castellanii (author's transl).it could be shown that extracts of growing cultures of acanthamoeba castellanii contained a cellulose degrading system. reducing sugars are split off by one component of this system at an optimum of ph 4, another enzyme changes the viscosity at an optimum of ph 6, and a third component is a beta-glucosidase with an optimum at ph 3.5. at ph 4 the cellulose degradation products are cellobiose and glucose; at ph 6 higher molecular weight oligosaccharides are produced. during the development from tr ...197718125
activity and distribution of bacteriolytic n-acetyl-muramidase during growth of acanthamoeba castellanii in axenic culture.bacteriolytic endo n-acetylmuramidase of acanthamoeba castellanii has been studied. in amoeba cells the enzyme, like exo n-acetylglucosaminidase and acid phosphatase, is attached to the lysosomes, as it is sedimentable when homogenates are prepared in medium containing sucrose. the sedimentability could be abolished by treatment with triton x-100, thermal disintegration or by osmotic shock. the sedimentability and acid ph optima of the enzyme are highly characteristic of lysosomes. however, in y ...197881598
electron microscopic studies of acanthamoeba castellanii infected with obligate intracellular bacterial parasite. 197989791
characterization of cytoplasmic actin isolated from acanthamoeba castellanii by a new method.cytoplasmic actin has been isolated from acanthamoeba castellanii by a new method, employing chromatography on deae-cellulose, that improves the yield by more than 20-fold over the previously reported method. this procedure should be particularly useful for isolating actin from cells in which it is present in relatively low concentration because the method does not depend initially on the polymerization of actin or its interaction with myosin. systematic comparison of the properties of purified ...1976133106
inhibition by theophylline of phagocytosis in acanthamoeba castellanii.theophylline inhibited the phagocytosis of latex beads by acanthamoeba castellanii (neff). the cells recovered the ability to engulf beads after 1-2 hr of exposure to theophylline. cells which have been exposed to 25 mm theophylline for a period of inhibition and recovery were not inhibited further by incubation with a fresh medium containing the same concentration of theophylline. however, the medium in which the cells recovered was as effective as a fresh medium in inhibiting phagocytosis in a ...1976180290
synthesis of diphosphoinositide by a supernatant fraction from acanthamoeba castellanii.homogenates of the free-living amoeba acanthamoeba castellanii incorporate phosphate from [gamma-32p]atp into a lipid which co-chromatographs with diphosphoinositide on one- and two dimensional chromatography. incorporation into lipids similar in mobility to triphosphoinositide is not detected. the product co-chromatographs with diphosphoinositide whether exogenous phosphatidylinositol or total amoeba lipid is the substrate. the inositide kinase is almost entirely located in the supernatant frac ...1976183878
acid hydrolase activity during growth and encystment in acanthamoeba castellanii.the activity and sedimentation of acid phosphatase (apase), acid deoxyribonuclease (dnase), and acid ribonuclease (rnase) were investigated throughout growth and encystment in acanthamoeba castellanii. the activities/mg protein of all 3 hydrolases are high in young cultures and decrease to constant levels in postlog cells. the rnase activity/ameba decreases 50% during growth, whereas the activity/cell of both apase and dnase remains constant. the percent sedimentation at 20,000 g of all 3 enzyme ...1976187746
comparative biosynthesis of polyethylenic fatty acids in acanthamoeba castellanii and ochromonas danica.acanthamoeba castellanii were incubated in vivo with 1(-14)c linoleic and 1(-14)c-alpha-linolenic acids. the incorporation of the acids into lipid fractions was studied. labeling was found mainly in triglycerides and phospholipids. homogenized cells and subcellular fractions separated by centrifugation were incubated with 1-14c-linoleic. 1-14c -alpha-linoleic and 1-14c eicosa-8,11-dienoic acids in the presence of nadh, atp, and coa. different metabolic routes were demonstrated. omega3 and omega6 ...1975189569
peptide maps of the myosin isoenzymes of acanthamoeba castellanii.extracts of acanthamoeba castellanii contain four myosin-like atpases (maruta, h., gadasi, h., collins, j.h., and korn, e.d. (1979) j. biol. chem. 254, 3624-3630): double-headed acanthamoeba myosin ii and single-headed acanthamoeba myosins ia, ib, and ic, which have heavy chains of 170,000, 130,000, 125,000, and 130,000 daltons, respectively, as well as different light chains. in the accompanying paper, evidence is presented that suggests that acanthamoeba myosin ic is the same molecule as acant ...1979429373
dna-dependent rna polymerase iii from acanthamoeba castellanii: comparison of the catalytic properties of the trophozoite and cyst enzymes.dna-dependent rna polymerase iii was partially purified from trophozoites and immature cysts of the small soil ameba, acanthamoeba castellanii. in contrast to the active modulation of the variety of transfer rna species which are transcribed during encystment, no difference was found in the chromatographic or catalytic properties of the enzyme responsible for their transcription.1979490436
dna-dependent rna polymerases from acanthamoeba castellanii. comparative subunit structures of the homogeneous enzymes.the constituent polypeptides of the three classes of dna-dependent rna polymerase from acanthamoeba castellanii were compared by several electrophoretic methods. polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (sds) reveals that a number of polypeptide components of the isozymes have identical molecular weights. two-dimensional electrophoresis (isoelectric focusing in 8 m urea:sds-polyacrylamide gel electrophoresis) demonstrates that the polypeptides of identical mol ...1979500645
a rapid and facile procedure for the preparation of rna polymerase i from acanthamoeba castellanii. purification and subunit structure. 1978659440
experimental acanthamoeba infections in mice pretreated with methylprednisolone or tetracycline.human infections due to free-living amebas of the genus acathamoeba have been reported sporadically, occasionally in individuals with underlying diseases. to determine if such infections may be considered opportunistic, groups of laboratory mice were pretreated with either methylprednisolone or tetracycline and inoculated intranasally with 1.075 times 10(4) acanthamoeba castellanii isolated from a natural fresh water well. results were compared with controls receiving either drug or amebas alone ...1978686155
x-ray microanalysis of calcium-dependent deposits at the plasma membrane of acanthamoeba castellanii. 1978689266
recurrent suppurative kerato-uveitis with loss of eye due to infection by acanthamoeba castellani. 1975775698
electron microscopic study of a pathogenic acanthamoeba castellani strain: the presence of bacterial endosymbionts. 1975803475
plasma membrane and soluble lysophospholipases of acanthamoeba castellanii. 1975811173
immunoassays of acanthamoeba castellanii plasma membranes. preliminary results.to facilitate future diagnosis of acanthamoeba infections in man, studies have been initiated to elicit antibodies to purified membranes from acanthamoeba species. specifically in this communication, preliminary results are reported on a. castellanii. immunoprecipitation and immunofluorescent analyses suggest that the membrane antisera may allow specific identification at the species level and possibly strain identification.1976818599
meningoencephalitis due to acanthamoeba sp. pathogenesis and clinico-pathological study.amebic meningoencephalitis (am) and primary amebic meningoencephalitis (pam) are infectious diseases essentially confined to the central nervous system (cns) and caused by free-living amebas of the genus acanthamoeba (a.) and naegleria (n.) respectively. am due to a. sp. (acanthamoeba castellanii and acanthamoeba culbertsoni) have been reported in chronically ill debilitated individuals, some of them under immunosuppressive therapy, or in immunologically impaired patients without a history of re ...1977857580
evidence for a cytosol counterpart of the major plasma membrane protein in acanthamoeba castellanii.isolated plasma membranes from acanthamoeba castellanii incorporated radio-activity when incubated in a corresponding labelled cytosol fraction. the incorporation increased linearly with time and reached saturation at high cytosol: membrane protein ratios in the incubation mixture. polyacrylamide gel electrophoresis of treated membranes showed that the major protein, which comprised 40 to 50% of the total, was labelled, suggesting that it had exchanged with a radioactive cytosol counterpart. the ...1977874451
pathogenic free-living amebae (pfla) from frozen swimming areas in oslo, norway.water samples were taken from 4 frozen swimming areas in oslo, norway and examined for pathogenic and non-pathogenic limax amebae. all samples contained amebae and 2 of the areas yielded pathogens (acanthamoeba castellanii). the relationship between distribution and temperature is discussed.1977905785
the effects of pesticides, polychlorinated biphenyls and metals on the growth and reproduction of acanthamoeba castellanii. 1977406955
characterization of a second myosin from acanthamoeba castellanii.we purified a 400,000 molecular weight myosin, myosin-ii, from acanthamoeba castellanii. the sequence of ion exchange chromatography, actomyosin precipitation, actin extraction, and gel permeation chromatography yields per 100 g of cells about 11 mg of myosin-ii which is 90 to 96% pure. atpase activity is highest in the presence of ca2+, but the enzyme is also active in edta provided high concentrations of k+ are present. the molecule consists of two 175,000 molecular weight heavy chains, one or ...1978149136
in vitro susceptibility of pathogenic naegleria and acanthamoeba speicies to a variety of therapeutic agents.six pathogenic strains of naegleria fowleri, two of acanthamoeba castellanii, and three of acanthamoeba polyphaga were tested in vitro for susceptibility to a variety of potentially useful therapeutic agents. minimal motility inhibitory concentrations and minimal inhibitory concentrations were determined by a technique of subculturing pure clones of amoebae in plastic tissue culture chamber slides containing liquid axenic media and serially diluted drug, incubating at 30 degrees c for acanthamoe ...1976984777
purification from acanthamoeba castellanii of proteins that induce gelation and syneresis of f-actin.from acanthamoeba castellanii, we have purified four proteins each of which alone causes a solution of f-actin to gel. the four active proteins have subunit molecular weights of about 23,000, 28,000, 32,000 and 38,000, respectively; the last three may be dimers in their native proteins. together, these four proteins account for about 97% of the gelation activity of the whole extract; not more than about 3% of the total activity of the unfractionated extract can be due to a 250,000-dalton polypep ...1977137899
experimental pneumonitis and encephalitis caused by acanthamoeba in mice: pathogenesis and ultrastructural features.for a more precise definition of the clinicopathological features of experimental acanthamoebic infection in mice, trophozoites of acanthamoeba castellanii and acanthamoeba polyphaga were instilled intranasally into adult white mice. eight to 20 days after inoculation, severe pulmonary disease developed; one to two days later, neurological signs ensued. on pathologic examination an amebic broncho-pneumonia associated with encephalitis was found. trophozoites and cysts were seen in lung and brain ...197548530
dna-dependent rna polymerase i from acanthamoeba castellanii: comparison of the catalytic properties and subunit architectures of the trophozoite and cyst enzymes. 1978626499
comparison of pinocytosis and phagocytosis in acanthamoeba castellanii. 1977590362
chemiluminescence of acanthamoeba castellanii.1. chemiluminescence of acanthomoeba castellanii in the presence of o2 was of similar intensity in organisms harvested early or late during exponential growth [when cyanide (1 mm) stimulates or inhibits respiration respectively]. 2. cyanide (up to 1.5 mm) stimulated photoemission in both types of organism by 250--300 photons/s per 10(7) cells above the value observed under aerobic conditions. 3. 'dibromothymoquinone' (2,5-dibromo-6-isopropyl-3-methyl-p-benzoquinone) (up to 80 microm) further inc ...1979534514
properties of mitochondria isolated from cyanide-sensitive and cyanide-stimulated cultures of acanthamoeba castellanii.1. mitochondria isolated from cultures of acanthamoeba castellanii exhibit respiratory control and oxidize alpha-oxoglutarate, succinate and nadh with adp:o ratios of about 2.4, 1.4 and 1.25 respectively. 2. mitochondria from cultures of which the respiration was stimulated up to 50% by 1mm-cyanide (type-a mitochondria) and from cyanide-sensitive cultures (type-b mitochondria) had similar respiratory-control ratios and adp:o ratios. 3. state-3 rates of respiration were generally more cyanide-sen ...1978212020
dna-dependent rna polymerases from acanthamoeba castellanii. multiple forms of the class iii enzyme and levels of activity of the polymerase classes during encystment.multiple forms of class iii dna-dependent rna polymerase have been found in a number of higher eukaryotic cells types (chambon, p. (1975) annu. rev. biochem. 44, 613--638). similar multiple forms are reported here from a lower eukaryote, the soil amoeba acanthamoeba castellanii. the levels of activity of all three rna polymerase classes in whole cell extracts of acanthamoeba during cellular differentiation were examined. in contrast to our previous observation (detke, s. and paule, m.r. (1975) b ...1978698225
interaction of phospholipid vesicles with cells. endocytosis and fusion as alternate mechanisms for the uptake of lipid-soluble and water-soluble molecules.depending on their phospholipid composition, liposomes are endocytosed by, or fuse with, the plasma membrane, of acanthamoeba castellanii. unilamellar egg lecithin vesicles are endocytosed by amoeba at 28 degrees c with equal uptake of the phospholipid bilayer and the contents of the internal aqueous space of the vesicles. uptake is inhibited almost completely by incubation at 4 degrees c or in the presence of dinitrophenol. after uptake at 28 degrees c, the vesicle phospholipid can be visual ...19751174130
[experimental acanthamoeba castellani infections in white mice. histopathological changes]. 19751212078
dna-dependent rna polymerase iii from acanthamoeba castellanii. a rapid procedure for the large scale preparation of homogeneous enzyme. 1978681349
the cytochromes of acanthamoeba castellanii.1. low-temperature difference spectra of gradient-purified mitochondria of acanthamoeba castellanii reveal the presence of cytochromes b-555, b-562 and c-549, with a-type cytochromes having a broad asymmetrical maximum at 602 nm; these components were also observed in specta of whole cells. 2. the a-type cytochromes are unusual in that they have split soret absorption maxima (at 442 and 449 nm) and an uncharacteristic co difference spectrum. 3. co difference spectra of whole cells and 'microsoma ...1977597258
the effect of inhibitors on the oxygen kinetics of terminal oxidases of acanthamoeba castellanii.1. respiration of growing cultures of acanthamoeba castellanii is inhibited less than 60% by azide (35 mm); the respiration of early-exponential-phase cultures differs from that of late-exponential-phase cultures in being stimulated by up to 120% by low concentrations (less than 1 mm) of this inhibitor. azide (0.5 mm) plus 1 mm-salicylhydroxamic acid gives 80% inhibition of respiration in early- or late-exponential-phase cultures. 2. lineweaver-burk plots of 1/v against 1/[o2] for growing and st ...1979496900
properties of a soluble polyprenyl phosphate: udp-d-glucose glucosyltransferase.a soluble enzyme that catalyzes the transfer of d-glucose from udp-d-glucose to dolichyl phosphate has been prepared by sonic oscillation of acanthamoeba castellani cysts. the product of catalysis is dolichyl beta-d-glucosyl phosphate. the enzyme requires a divalent cation, either magnesium or manganese, and the presence of a reducing agent for maximum activity. solanesyl phosphate and ficaprenyl phosphate are alternative substrates, apparently at lower rates, but gdp-d-glucose, udp-d-glucuronic ...1979438216
dna-dependent rna polymerase ii from acanthamoeba castellanii. large scale preparation and subunit composition. 1979438176
isolation and characterization of a cycloheximide-resistant mutant of acanthamoeba castellanii neff.a cycloheximide-resistant mutant was isolated from the amoeba acanthamoeba castellanii neff. drug resistance was found to be due to a ribosomal modification.1979438133
interactions of surface-active alkyltrimethylammonium salts with the plasma membrane of acanthamoeba castellanii.the interactions of three surface-active alkyltrimethylammonium salts (c12-c16) with the plasma membrane of acanthamoeba castellanii were studied. the surfactants caused a release of k+ from the cells at premicellar concentrations. the lytic effectiveness of the surfactants increased with an increase in the length of the alkyl chain with about an order of magnitude for every two carbon atoms added to the alkyl chain. binding studies with the c16 homologue revealed that at a concentration corresp ...1979433611
cloning and expression of the acanthamoeba castellanii gene encoding transcription factor tfiid.we have cloned and characterized the cdna encoding transcription factor tfiid from the eukaryote, acanthamoeba castellanii. the gene occurs as a single species, encodes one mrna and, presumably, a single protein. a. castellanii tfiid contains two recognizable domains, a nonconserved n-terminal domain and a highly conserved c-terminal domain. similarities between the amino acid (aa) sequences of tfiid from several organisms are also found within the n-terminal 78 aa, suggesting a potential role i ...19921339370
dna synthesis in growth and encystment of acanthamoeba castellanii.differentiation of acanthamoeba castellanii into dormant cysts occurs spontaneously in stationary phase cultures, or can be induced experimentally by starvation. although no further increase in cell density occurred after induction in either case, incorporation of [h]thymidine into dna continued at a reduced rate through the period when differentiated products (cyst wall components) were formed. no net accumulation of dna occurred during differentiation, indicating that the dna synthesis occurri ...1975124743
the neuraminidases of trypanosoma cruzi and acanthamoeba castellanii are immunologically related.we have recently reported the presence of neuraminidase (na) activity in acanthamoeba castellanii. we now show that the nas of t. cruzi and a. castellanii share cross-reactive determinants using tcn-2, a monoclonal antibody (mab) against the t. cruzi na and a mouse polyclonal ab (anti-tr) raised against a tandemly repeated dodecapeptide which contains the epitope recognized by tcn-2 (prioli et al., submitted). this cross-reactivity was demonstrated by the reaction of tcn-2 and anti-tr with a. ca ...19921376002
induction of delta 12-desaturase activity during temperature adaptation in acanthamoeba castellanii. 19921397555
acanthamoeba castellanii rna polymerase ii transcription in vitro: accurate initiation at the adenovirus major late promoter.we have developed and characterized an efficient in vitro system from the protozoan, acanthamoeba castellanii, that accurately initiates transcription from the adenovirus-2 major late promoter (admlp). transcription by a. castellanii rna polymerase ii (pol ii) is initiated at the same nucleotide (nt) that is used by hela extracts and is dependent upon adenovirus sequences located between nt -51 and the region around the transcription start point (tsp). the results suggest that the a. castellanii ...19921398130
interactions between actin, myosin, and an actin-binding protein from rabbit alveolar macrophages. alveolar macrophage myosin mg-2+-adenosine triphosphatase requires a cofactor for activation by actin.the interactions were analyzed between actin, myosin, and a recently discovered high molecular weight actin-binding protein (hartwig, j. h., and stossel, t. p. (1975) j. biol chem.250,5696-5705) of rabbit alveolar macrophages. purified rabbit alveolar macrophage or rabbit skeletal muscle f-actins did not activate the mg2+atpase activity of purified rabbit alveolar macrophage myosin unless an additional cofactor, partially purified from macrophage extracts, was added. the mg2+atpase activity of c ...1975124735
acanthamoeba keratitis: synergy between amebic and bacterial cocontaminants in contact lens care systems as a prelude to infection.we encountered a patient with acanthamoeba keratitis whose contact lens care solution contained numerous trophozoites and cysts admixed with xanthomonas maltophilia organisms, many of which were adherent to the trophozoite surface and internalized within endocytic vacuoles. because of this finding, we investigated the role of bacterial cocontaminants in contact lens care systems as substrates for the growth of acanthamoeba spp. individual cocultivation of acanthamoeba castellanii and a. polyphag ...19921401013
chemotactic response of macrophages to acanthamoeba castellanii antigen and antibody-dependent macrophage-mediated killing of the parasite.the chemotactic potential of antigens of acanthamoeba castellanii for macrophages and the ability of naive and immune rat peritoneal macrophages to kill a. castellanii in vitro were assessed. the amoebolytic capacity of immune rat serum and complement was also examined. no parasite was killed in the presence of heat-inactivated naive rat serum. low numbers of parasites were lysed in the presence of heat-inactivated immune rat serum, whereas significantly greater numbers of parasites were lysed i ...19921403427
isolation of genomic dna encoding transcription factor tfiid from acanthamoeba castellanii: characterization of the promoter.we have isolated a genomic clone encoding acanthamoeba castellanii tfiid. the clone contains the entire tfiid gene, 300 bp of 5' promoter sequences and several hundred base pairs of 3' non-coding sequence. the coding region is interrupted by two short introns, but is otherwise identical to acanthamoeba tfiid cdna. comparisons between forty four acanthamoeba intron 5' and 3' boundaries suggest a 5' splice site consensus of gtacg(t/c) and a 3' consensus of cag. we determined the position of the tr ...19921408796
kinetics of cell agglutination. a quantitative assay of concanavalin a mediated agglutination of acanthamoeba castellanii. 1976954862
comparative antigenic analysis of pathogenic and free-living naegleria species by the gel diffusion and immunoelectrophoresis techniques.antigens prepared from each of five strains (ca, cj, hb-1, hb-3, and ty) of pathogenic naegleria and the eg strain of nonpathogenic naegleria gruberi were compared by the gel diffusion and immunoelectrophoresis techniques. axenically grown amoebae were used as sources of antigens. antisera were produced in individual rabbits against three strains (ca, cj, and hb-1) of pathogenic naegleria and the eg strain of n. gruberi. in the gel diffusion experiment each of the six antigens was reacted with e ...1975803926
purification of components required for accurate transcription of ribosomal rna from acanthamoeba castellanii.the components required for specific transcription of ribosomal rna were isolated from logarithmically growing acanthamoeba castellanii. the transcription initiation factor fraction, tif, and rna polymerase i were extracted from whole cells at 0.35 m kcl. the extract was fractionated with polyethylenimine, then chromatographed on phosphocellulose (p11) which resulted in the separation of tif from rna polymerase i. the fractions containing tif were further chromatographed on deae cellulose (de52) ...19921620619
two forms of bacteriolytic endo-n-acetylmuramidase in acanthamoeba castellanii.two different molecular forms of bacteriolytic endo-n-acetylmuramidase (ec 3.2.1.17) were found in the acanthamoeba castellanii culture. the enzymes were separated by column chromatography on deae-sephadex or by polyacrylamide-gel electrophoresis. in young cultures only one molecular form of the enzyme was selectively secreted by amoeba cells to the environment. the second, more basic enzyme protein was preferentially synthesized by aging acanthamoeba castellanii cells, and was also liberated to ...1978752200
sequence and organization of 5s rna genes from the eukaryotic protist acanthamoeba castellanii.a 5s rna genomic clone has been isolated from acanthamoeba castellanii and the sequence of the coding region plus flanking dna was determined. this clone encodes an rna whose sequence matches that of 5s rna from this organism. there is sequence similarity in the 5'-flanking region to other eukaryotic 5s rna genes which require or are greatly affected by upstream regions for transcriptional activity. the immediate 3'-flanking region has a termination sequence similar to that found in all genes th ...19911676384
mutants of acanthamoeba castellanii resistant to erythromycin, chloramphenicol, and oligomycin.cell lines of acanthamoeba castellanii resistant to erythromycin (eryr), chloramphenicol (capr), and oligomycin (olir) have been isolated. these may be the first such mutants for a. castellanii. these mutants have been phenotypically stable for 2 years, surviving storage and vegetative multiplication in the absence of drugs. resistance was specific for each drug, but double mutants (e.g. eryrcapr) were obtained by stepwise selection. mutant frequencies were determined in multiwell plates; less t ...1978739412
dna-dependent rna polymerase ii from acanthamoeba castellanii. comparison of the catalytic properties and subunit architectures of the trophozoite and cyst enzymes.the actively growing cells (trophozoites) of the amoeba acanthamoeba castellanii were found to contain three or perhaps four different forms of class ii dna-dependent rna polymerase (ec 2.7.7.6). the chromatographic and catalytic properties of all forms of the acanthamoeba class ii polymerases suggest them to be cognates of the class ii polymerases previously reported. the predominant form was purified to near homogeneity and its subunit composition determined. nine different polypeptides were f ...1978708741
phagocytosis and pinocytosis in acanthamoeba castellanii.endocytotic activity of acanthamoeba trophozoites attenuates once the cells enter stationary phase in liquid culture. phagocytosis, monitored by the ingestion of polystyrene latex beads, essentially ceases and the uptake of [3h]inulin, known to be mediated by pinocytosis, is reduced by about half. the reduced pinocytotic activity of stationary-phase cells remains sensitive to respiratory inhibitors. preincubation of stationary-phase cells in fresh growth medium for 1-5 h before the initiation of ...19761255130
enzymes of phospholipid metabolism in the plasma membrane of acanthamoeba castellanii.phospholipase a, lyophospholipase, acyl coa hydrolase, and palmitoyl coa synthetase are present in the plasma membrane of acanthamoeba castellanii. the first three of these enzymes also occur in other cell fractions but in concentrations too low for the activities in the plasma membrane fraction to be accounted for by contamination by any other cell fraction. palmitoyl coa synthetase is restricted almost entirely to the plasma membrane and microsomal fractions; the microsomal activity is too low ...19751110322
lipid changes in individual membranes of acanthamoeba castellanii during temperature adaptation. 19911783154
dna-dependent rna polymerases from acanthamoeba castellanii: properties and levels of activity during encystment.three dna-dependent rna polymerases have been isolated and partially purified from trophozoites of acanthamoeba castellanii. separated by deae-sephadex chromatography, they have been designated polymerases, i, iia and iib according to their alpha-amanitin sensitivity and kinetic properties. i is completely insensitive to alpha-amanitin. iia and iib are sensitive to low concentrations (0.1 mug/ml) of alpha-amanitin; however, in order to achieve 100% inhibition much higher concentrations (130 mug/ ...19751122326
purification of actobindin from acanthamoeba castellanii. 19911851935
purification of myosin i and myosin i heavy chain kinase from acanthamoeba castellanii. 19911851936
effect of glucose on glycine requirement of acanthamoeba castellanii.acanthamoeba castellanii grows in a minimal medium (amliv) containing only arginine, methionine, leucine, isoleucine, and valine as sole nitrogen sources, other than vitamins, when glucose is the carbon source. with acetate as the carbon source, glycine must be added to amliv. doubling time in amliv varies according to the ratio of amino acids concentrations. several combinations yield td values of approximately 70 hr.1976972355
in vitro penetration of human corneal epithelium by acanthamoeba castellanii: a scanning and transmission electron microscopy study.human corneal buttons were exposed to acanthamoeba castellanii trophozoites and cysts for 12 hours at 35 degrees c. the buttons examined by light microscopy and scanning and transmission electron microscopy had severe epithelial ulceration and penetration by trophozoites. observations on trophozoites below the surface suggest that penetration is accomplished by both secreted cytolytic enzymes and phagocytosis. it is likely that the secretion of one or more enzymes constitutes the initial step in ...19911889214
in vitro intercellular adherence of acanthamoeba castellanii: a scanning and transmission electron microscopy study.human corneal buttons were exposed to trophozoites and cysts of acanthamoeba castellanii for 12 hours. examination of the buttons by scanning electron microscopy showed numerous trophozoites on the surface of the epithelium. trophozoites examined by transmission electron microscopy had limited regions of attachment to the epithelium but extensive regions of attachment to each other. attachment regions were characterized as plaque-like maculae of an incomplete desmosome junction. firm attachment ...19911889215
quantation by flow microfluorometry of total cellular dna in acanthamoeba.the dna content of five species of acanthamoeba was determined by flow microfluorometry. acanthamoeba castellanii (ac-30), acanthamoeba polyphaga (apg and p-23), acanthamoeba rhysodes, acanthamoeba culbertsoni (a-1), and acanthamoeba royreba were grown in a casitone based medium 24-48 hr. the trophozoites were harvested, and evaluated for dna-bound fluorescence. all species tested has dna values between 2.0-5.0 pg/cell. these results placed dna/cell values of acanthamoeba slightly lower than dna ...1978361883
restriction enzyme analysis of mitochondrial dna of acanthamoeba strains in japan.eight isolates, identified as either acanthamoeba castellanii or a. polyphaga from human eye infections, contact lens containers, and soil in japan, were characterized by restriction fragment length polymorphisms (rflp) of mitochondrial dna (mtdna). mitochondrial dna was digested with either bgl ii, ecor i, hind iii, hpa i, sca i or xba i, electrophoresed in agarose gels, and stained with ethidium bromide. four distinct rflp phenotypes that refer to the collection of six fragment size patterns o ...19901982316
specific transcription of an acanthamoeba castellanii 5s rna gene in homologous nuclear extracts.an rna polymerase iii in vitro transcription system has been developed from the protist acanthamoeba castellanii. the system is dependent on a cloned 5s rna gene and utilizes a nuclear extract which contains all the necessary protein components. the system is assembled from completely homologous components. primer extension and rna sequencing analysis confirm that the in vitro 5s rna transcript is identical to the 5s rna isolated from cells. the transcription complex forms unusually rapidly on t ...19912027775
molecular aspects of the cell cycle and encystment of acanthamoeba.evidence for subdivision of the cell cycle of acanthamoeba into ultradian biochemical cycles is accumulating, and a linkage between these cycles and the length of the cell cycle is possible. the dna replication cycle differs with the method of assay: no g1 phase is found in asynchronous cultures, and a long g1 phase is found in synchronous cultures. encystment most likely occurs from g2, but whether it is limited to a portion of this phase is not clear. encystment-enhancing factors are released ...19912047666
infection of the central nervous system due to acanthamoeba.it is well established that acanthamoeba castellanii, acanthamoeba culbertsoni, acanthamoeba polyphaga, and probably other species of free-living amebas are virulent opportunists capable of producing disease in humans and animals. human infections involving brain, eyes, skin, and lungs have been reported from all continents. central nervous system (cns) infection due to acanthamoeba species usually occurs in chronically ill, debilitated individuals, some of them receiving immunosuppressive thera ...19912047674
adherence of acanthamoeba castellanii cysts and trophozoites to extended wear soft contact lenses. 19912047681
scanning electron microscopy of acanthamoeba castellanii: adherence to surfaces of new and used contact lenses and to human corneal button epithelium. 19912047683
screening for chemical inhibitors of growth rate, encystment, and excystment in acanthamoeba castellanii. 19912047691
effect of magainins on acanthamoeba castellanii. 19912047693
characterization of the genome of the small free-living amoeba acanthamoeba castellanii.the cellular dnas of acanthamoeba castellanii have been characterized by their behaviour in csc1 density gradients, by their thermal denaturation and by their renaturation kinetics. whole-cell dna exhibits, on csc1 density gradients, a major peak with a density of 1.717 g/cm3 (major component) and a minor peak with a density of 1.692 g/cm3 (minor component). the major component is nuclear and the minor component is of cytoplasmic origin. the latter contains mitochondrial dna as well as an extram ...19751148249
ultraviolet radiation for the sterilization of contact lenses.two sources of ultraviolet (uv) radiation with peak wavelengths in the uv-c or uv-b ranges were compared for their ability to sterilize contact lenses infected with pseudomonas aeruginosa, streptococcus pneumoniae, acanthamoeba castellani, candida albicans, and aspergillus niger. also examined was the effect of prolonged uv light exposure on soft and rigid gas permeable (rgp) contact lenses. the uv-c lamp (253.7 nm, 250 mw/cm2 at 1 cm) was germicidal for all organisms within 20 minutes but cause ...19902123422
localization of acid phosphatase in acanthamoeba castellanii with light and electron microscopy during growth and after phagocytosis. 19761003596
the role of actin in the temperature-dependent gelation and contraction of extracts of acanthamoeba.the temperature-dependent assembly and the interaction of acanthamoeba contractile proteins have been studied in a crude extract. a cold extract of soluble proteins from acanthamoeba castellanii is prepared by homogenizing the cells in a sucrose-atp-ethyleneglycol-bis-(beta-aminoethyl ether) n,n'-tetraacetic acid buffer and centrifuging at 136,000 g for 1 h. when this supernate of soluble proteins is warmed to room temperature, it forms a solid gel. upon standing at room temperature, the gel slo ...19761030705
regulation of the actin-activated atpase activity of acanthamoeba myosin ii by copolymerization with phosphorylated and dephosphorylated peptides derived from the carboxyl-terminal end of the heavy chain.myosin ii from acanthamoeba castellanii is a conventional myosin composed of two heavy chains and two pairs of light chains. the amino-terminal approximately 90 kda of each heavy chain form a globular head that contains the atpase site and an atp-sensitive actin-binding site. the carboxyl-terminal approximately 80 kda of both heavy chains interact to form a coiled coil, helical rod (through which the molecules self-associate into bipolar filaments) ending in a short nonhelical tailpiece. phospho ...19902141027
isolation and electrophoretic analysis of nucleoli, phenol-soluble nuclear proteins, and outer cyst walls from acanthamoeba castellanii during encystation initiation.a technique is described for isolating nuceoli from acanthamoeba castellanii. nuclei isolated by a modification of the technique of f. j. chlapowski and r. n. band (1971) are sonicated in a surcrose-tris-mgso4-kc1-triton x-100 buffer and centrifuged on a linear sucrose gradient extending from 1.3 m to 1.5 m with a 2.6 m cushion, at 41000 rpm for 90 min. the only apparent contaminants in the nucleolar preparation are outer cyst walls. a procedure is described for the isolation of chemically pure ...19761030709
the start site of the acanthamoeba castellanii ribosomal rna transcription unit.the 39s ribosomal rna (rrna) precursor has been isolated from acanthamoeba castellanii. in vitro capping of the isolated rna verified that it is the primary transcript and identified the 5' nucleotide as pppa. the position of the 5' coding nucleotide on the rrna repeat unit sequence was identified using northern blot, r-loop, and s1 nuclease mapping techniques. dinucleotide priming of an in vitro transcription system stalled because of low initiating nucleotide concentration revealed that apa ma ...19921617304
in vivo and in vitro collagenolytic activity of acanthamoeba castellanii.axenic cultures of acanthamoeba castellanii contained a collagenolytic enzyme that digested collagen shields and purified collagen in vitro. specificity of biologic activity was determined by the addition of selected enzyme inhibitors to the assays and revealed that the parasite-conditioned medium contained both collagenase and lower concentrations of other proteolytic enzymes. however, most of the collagenolytic and pathogenic activity was directly attributable to specific collagenase. intrastr ...19902173683
phagocytosis in acanthamoeba: ii. soluble and insoluble mannose-rich ligands stimulate phosphoinositide metabolism.the generation of second messengers during phagocytosis of yeast by acanthamoeba castellanii was examined. the kinetics of binding and internalization of yeast by acanthamoeba were measured and this was compared with the generation of known second messengers. we observed stimulated degradation of pi-4, 5-p2 to 1,4,5 ip3 with kinetics similar to that observed for the binding of yeast to amoeba. similar production of ip3 could be induced upon treatment with a soluble mannosylated glycoprotein. we ...19902177061
immunolocalization of myosin i heavy chain kinase in acanthamoeba castellanii and binding of purified kinase to isolated plasma membranes.the actin-activated mg(2+)-atpase activities of acanthamoeba myosins i are known to be maximally expressed only when a single threonine (myosin ia) or serine (myosins ib and ic) is phosphorylated by myosin i heavy chain kinase. the purified kinase is highly activated by autophosphorylation and the rate of autophosphorylation is greatly enhanced by the presence of acidic phospholipids. in this paper, we show by immunofluorescence and immunoelectron microscopy of permeabilized cells that myosin i ...19911655799
cdna sequence analysis of a 29-kda cysteine-rich surface antigen of pathogenic entamoeba histolytica.a gamma gt11 cdna library was constructed from poly(u)-sepharose-selected entamoeba histolytica trophozoite rna in order to clone and identify surface antigens. the library was screened with rabbit polyclonal anti-e. histolytica serum. a 700-base-pair cdna insert was isolated and the nucleotide sequence was determined. the deduced amino acid sequence of the cdna revealed a cysteine-rich protein. dna hybridizations showed that the gene was specific to e. histolytica since the cdna probe reacted w ...19902201027
differentiation in acanthamoeba castellanii. 1976791066
acanthamoeba keratitis successfully treated with prolonged propamidine isethionate and neomycin-polymyxin-gramicidin.we report a case of acanthamoeba castellanii keratitis that was successfully treated with intense propamidine isethionate and neomycin-polymyxin-gramicidin over 11 and nine days, respectively. the frequency with which the medications were applied, once every 30 minutes with each medication, has been surpassed only once before in reported cases. additional medical treatment included topical miconazole 1% drops for five days and clotrimazole 1% drops for one day; the latter was discontinued due to ...19901689978
effect of growth temperature on fatty acid biosynthesis in acanthamoeba castellanii. 19902276479
susceptibility of corneas from various animal species to in vitro binding and invasion by acanthamoeba castellanii [corrected].a crucial requirement for establishing corneal infection by the extracellular protozoal parasite, acanthamoeba, is the ability of the parasite to bind to the corneal surface. in a series of in vitro studies, we examined the ability of acanthamoeba castellanii [corrected] to adhere, invade, and damage normal, intact corneas of 11 mammalian and one avian species. a. castellanii [corrected] (80-90% trophozoites and 10-20% cysts) were incubated with corneas for 24 hours in vitro and examined by scan ...19921730531
the covalent structure of acanthamoeba actobindin.actobindin is a protein from acanthamoeba castellanii with bivalent affinity for monomeric actin. because it can bind two molecules of actin, actobindin is a substantially more potent inhibitor of the early phase of actin polymerization than of f-actin elongation. the complete amino acid sequence of 88 residues has been deduced from the determined sequences of overlapping peptides obtained by cleavage with trypsin, staphylococcus v8 protease, endoproteinase asp-n, and cnbr. actobindin contains 2 ...19902376577
rapid diagnosis of acanthamoeba keratitis from corneal scrapings using indirect fluorescent antibody staining.two soft contact lens wearers using a homemade saline solution developed corneal stromal inflammation and epithelial ulceration and were both treated for months with a presumptive diagnosis of herpes simplex keratitis. subsequently, corneal scrapings revealed refractile, cystic structures consistent with the appearance of acanthamoeba. this was rapidly confirmed by indirect fluorescent antibody studies, and acanthamoeba castellani was later identified by growth in culture in both cases. acantham ...19862428344
preliminary characterization of an organism isolated from a case of viluy encephalomyelitis indicates a protozoal, rather than viral, aetiology.a microbial agent was isolated previously from a case of viluy encephalomyelitis and named the 'kpn agent' after the initials of the patient. here a detailed characterization of nucleic acids extracted from the purified kpn agent is presented. the agent contains both dna and rna, and has its own trnas and some other low-mr rnas, including 5s rna. these findings, and the isolation of eukaryotic-type ribosomes, suggest that the kpn agent is not a virus, as believed before, but a more complex micro ...19862428925
rapid visualization of acanthamoeba using fluorescein-conjugated lectins.we investigated the efficacy of fluorescein-conjugated lectins (fcls) for the rapid visualization of acanthamoeba species. cultures of acanthamoeba castellani, acanthamoeba culbertsoni, and acanthamoeba polyphaga were established on nonnutrient agar plates supplemented with escherichia coli. maximal trophozoite populations were established four to five days after initial subculturing; mature cysts were routinely noted three to six days later. at various time points, trophozoites and/or cysts wer ...19882458096
characterization of actin filament severing by actophorin from acanthamoeba castellanii.actophorin is an abundant 15-kd actinbinding protein from acanthamoeba that is thought to form a nonpolymerizable complex with actin monomers and also to reduce the viscosity of polymerized actin by severing filaments (cooper et al., 1986. j. biol. chem. 261:477-485). homologous proteins have been identified in sea urchin, chicken, and mammalian tissues. chemical crosslinking produces a 1:1 covalent complex of actin and actophorin. actophorin and profilin compete for crosslinking to actin monome ...19911757465
cellulose synthesis by extracts of acanthamoeba castellanii during encystment. stimulation of the incorporation of radioactivity from udp-(14c)glucose into alkali-soluble and insoluble beta-glucans by glucose 6-phosphate and related compounds.1. the activity of a particulate enzyme prepared from encysting cells of acanthamoeba castellanii (neff), previously shown to catalyze the incorporation of glucose from udp-[14c]glucose into both alkali-soluble and alkali-insoluble beta-(1 leads to 4) glucans, was stimulated several fold by glucose-6-phosphate and several related compounds. 2. incorporation was observed when [14c]glucose-6-p was incubated with the particles in the presence of udp-glucose. the results of product analysis by parti ...19761260020
functional implications of the unusual amino acid sequence of the regulatory light chain of acanthamoeba castellanii myosin-ii.we have determined by protein chemistry methods the amino acid sequence of light chain 2 from acanthamoeba castellanii myosin-ii (alc2). this is the first reported sequence for any protozoan myosin light chain. alc2 consists of 154 amino acid residues, including a single residue of his and two residues each of pro and tyr, and lacks cys and trp. the n-terminus is blocked, and if an n-terminal acetyl group is assumed. alc2 has a calculated molecular weight of 17,657. alc2 is an acidic protein, wi ...19911791194
lipophosphonoglycan of the plasma membrane of a canthamoeba castellanii. inositol and phytosphingosine content and general structural features.lipophosphonoglycan, a major component of the plasma membrane of acanthamoeba castellanii, has now been shown to contain 8% inositol and 13% c25- and c24-phytosphingosines in addition to the previously identified content of neutral sugars (26%), amino sugars (3%), aminophosphonates (10%), acidhydrolyzable phosphate (3%), and long chain fatty acids (14%). the fatty acids and phytosphingosines are in ceramide groups. lipophosphonoglycan can be separated by dodecyl sulfate-polyacrylamide electropho ...19761270435
membrane carbohydrate characterization of acanthamoeba astronyxis, a. castellanii and naegleria fowleri by fluorescein-conjugated lectins.a comparative study of membrane carbohydrate characteristics of pathogenic and non-pathogenic trophozoites and cysts of free-living acanthamoeba castellanii, naegleria fowleri and a. astronyxis, respectively from sewage sludge in india was carried out by means of fluorescein-conjugated lectin binding using eight lectins. two lectins, viz. concanavalin a and phytohaemagglutinin p, could bind all free-living amoebae at different concentrations. the most notable feature of the study is that peanut ...19892592141
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