bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of a Neutral Aminoacyl‐Peptide Hydrolase from Naegleria fowleri1
Authors: MARCIANO‐CABRAL F. , STANITSKI SUSAN , RADHAKRISHNA V. , BRADLEY S. G. 
Published: May 2007

ABSTRACTAn intracellular alpha‐aminoacyl‐peptide hydrolase (EC 3.4.11.‐) from Naegleria fowteri nN68 (ATCC 30894) has been characterized. The enzyme preparation hydrolyzed phenylalanyl‐, tyrosyl‐, leucyl‐, arginyl‐, alanyl‐, tryptophanyl‐, histidyl‐, methionyl‐, and lysyl‐naphthylamide but not benzoylleucyl‐, leucylglycyl‐, glycylprolylleucyl‐, glycyl‐, threonyl‐, aspartyl‐, or glutamyl‐naphthylamide. The aminopeptidase activity was inhibited by the cysteine‐protease inhibitors—hydroxymercuribenzoate, chloromercurisulfate, and iodoacetate‐ by the aminopeptidase inhibitors‐bestatin and trans‐epoxysuccinyl‐leucyl‐agmatine‐ by an inhibitor of soluble alanyl aminopeptidase EC 3.4.11.14, puromycin, and by the metalloprotease inhibitor, o‐phenanthroline. The exopeptidase activity was not inhibited by the chelator, ethylenediaminetetraacetate, or the serine‐protease inhibitor, phenylmethylsulfonylfluoride. The pH optimum of the exopeptidase was between 7.0 and 8.0. Enzyme activity was stable at 55°C for 30 min, but all activity was lost after 15 min at 80°C. Enzyme activity was inhibited by 100 μM HgCI2 and CdCl2 but not by 1 mM CoCl2, CuCl2, MnCl2, NiCl2, FeCl2, or ZnCl2. Enzyme activity was inhibited by 0.1% sodium dodecyl sulfate but not by 0.2% Brij 35, Tween 20, Tween 80, or Triton X‐100.
Cell Surface Carbohydrate Differences in Wild and Mutant Strains of Crithidia fasciculata1
Authors: ESTEVES MANUEL JOSE GIL , ANDRADE ARNALDO FEITOSA BRAGA , ALVIANO CELUTA SALES , ROITMAN ISAAC , DE SOUZA WANDERLEY , ANGLUSTER JAYME 
Published: May 2007

ABSTRACTWild type Crithidia fasciculata and three drug‐resistant mutant strains that have shown “flagellar adherence” were studied as to their ability to agglutinate with lectins specific for receptor molecules containing N‐acetyl glucosamine, N‐acetyl galactosamine, galactose, mannose‐like residues, fucose, and sialic acid. Escherichia coli with mannose‐sensitive fimbriae was also used as an agglutination probe. The presence of D‐GalNAc, D‐Gal, and mannose‐like residues was detected in the wild strain. Generally, in the mutants, residues of these sugar units were present in greater concentrations when compared to the wild type strain. β‐Galactosidase treatment showed that β‐D‐Galp units are exposed on the cell membrane. All types of cell agglutination including flagellum‐flagellum (F‐F), flagellum‐soma (F‐S), and soma‐soma (S‐S) were observed when lectins were used; however, with E. coli only the F‐F type of cell agglutination was observed with the wild type strain and the TFRR1 mutant. All types of agglutination were observed with the other two mutants.
Ultrastructure of the Erythrocytic Stages of Plasmodium malariae1
Authors: ATKINSON CARTER T. , AIKAWA MASAMICHI , ROCK EDWIN P. , MARSH KEVIN , ANDRYSIAK PATRICIA M. , CAMPBELL GARY H. , COLLINS WILLIAM E. , HOWARD RUSSELL J. 
Published: May 2007

ABSTRACTThis report describes the fine structure of the erythrocytic stages of Plasmodium malariae. Erythrocytic parasites from a naturally acquired human infection and an experimentally infected chimpanzee were morphologically indistinguishable and structurally similar to other primate malarias. New findings included observations of highly structured arrays of merozoite surface coat proteins in the cytoplasm of early schizonts and on the surface of budding merozoites and the presence of knobs in the membranes of Maurer's clefts. Morphological evidence is presented suggesting that proteins are transported between the erythrocyte surface and intracellular parasites via two routes: one associated with Maurer's clefts for transport of membrane‐associated knob material and a second associated with caveolae in the host cell membrane for the import or export of host‐ or parasite‐derived substances through the erythrocyte cytoplasm.
An Intranuclear Microsporidium Associated with Acute Anemia in the Chinook Salmon, Oncorhynchus tshawytscha1
Authors: ELSTON R. A. , KENT M. L. , HARRELL L. H. 
Published: May 2007

ABSTRACTAn intranuclear microsporidium is described from hemoblastic cells of the chinook salmon, Oncorhynchus tshawytscha. The infection is associated with an acute anemia in the fish. Up to 47% of the hemoblast nuclei were infected in anemic fish. The organisms, found only in spleen and kidney tissues, were 1–2 μm in diameter and consisted of vegetative and early sporulation forms. This microsporidium differs from known species which parasitize fish in its tissue location; however, the absence of mature spores and other life cycle stages precludes determination of its precise taxonomic identity.
Extracellular Killing of Trypanosoma cruzi Amastigotes by Human Eosinophils1
Authors: VILLALTA FERNANDO , PANKRATZ H. STUART , KIERSZENBAUM FELIPE 
Published: May 2007

ABSTRACTGranules released from human eosinophils upon interaction with Trypanosoma cruzi amastigotes in vitro were seen attached to the surface of non‐internalized parasites by electron microscopy. Amastigote damage was preceded by the binding of eosinophil granule material to its membrane, and eosinophil granule major basic protein (MBP) bound to the parasite surface was readily detectable. Additional evidence of eosinophil cytotoxicity for extracellular amastigotes was the observation that amastigotes trapped between two eosinophils, without being ingested by either one, were destroyed at the interface. Amastigotes isolated from the spleens of infected mice or grown in culture were similarly sensitive to the lytic effects of purified MBP. These results demonstrate the ability of human eosinophils to lyse T. cruzi amastigotes extracellularly in the absence of antibody and suggest that MBP may be involved in the effect. Thus, eosinophils, known to be capable of destroying phagocytosed amastigotes, could also contribute to the clearance of these parasites through extracellular killing.
Populations of Leucocytozoon Gametocytes in Blue Grouse (Dendragapus obscurus) from Hardwicke Island, British Columbia1
Authors: Allan R. A. , Mahrt J. L. 
Published: May 2007

ABSTRACTPopulation dynamics of round and elongate gametocytes of Leucocytozoon in wild and captive blue grouse (Dendragapus obscurus (Say)) from Hardwicke Island, British Columbia, were studied from 1980 to 1982. Blue grouse chicks were sampled weekly throughout each transmission season. Three patterns in the type of gametocyte produced during primary infection were observed in naturally‐infected captive and wild blue grouse chicks. Such variation in the expression of the gametocyte stage within a single host population suggests a different interpretation than has been previously reported for species of Leucocytozoon. The data from the primary patterns and profiles coupled with reexposure data and the asynchronous appearance of round and elongate gametocytes can be best interpreted as infection with two concurrent species of Leucocytozoon in blue grouse. More detailed research on the life cycle is necessary to confirm if two species of Leucocytozoon exist in blue grouse.
Corrections in the Names of Rodent Coccidia (Apicomplexa, Coccidiasina)
Authors: Levine Norman D. , Ivens Virginia R. 
Published: May 2007

ABSTRACTThe following new taxonomic combinations are introduced for coccidia whose names were previously given erroneously Dorisa bengalensis (Bandyopadhyay & Ray, 1982) n. comb, from the Indian palm squirrel Funambulus pennanti in India; Eimeria sicistae from the intestine of the birch mouse Sicista tianschanica in the USSR; E. hydrochaeri Carini. 1937 emend, from the capybara Hydrochaerus hydrochaerus in South America; Frenkelia sp. (Doby, Jeannes & Rault, 1965) from the brain of the water vole Arvicola sapidus in Europe; Frenkelia sp. (Karstad, 1963) from the brain of the muskrat Ondatra zibethica in North America; Frenkelia sp (Enemar, 1965) from the brain of the lemming Lemmus lemmus in Europe; Frenkelia sp. (Šebek, 1975) from the brain of the field mouse Apodemus flavicollis in Europe; and Sarcocystis sp. (Ryan, Wyand & Nielsen, 1982) from the skeletal muscles of the muskrat Ondatra zibethica in North America.
The Effect of Puromycin and Cycloheximide on the Infection of Algae‐Free Paramecium bursaria by Symbiotic Chlorellae1
Authors: AYALA ALFRED , WEIS DALE S. 
Published: May 2007

ABSTRACTIt has been suggested that the infection of algae‐free Paramecium bursaria by symbiotic algae involves an induction in the ciliate. Such a process suggests a need for the synthesis of specific proteins. Therefore, an attempt was made to determine the role of protein synthesis during the initial phases of host‐symbiont interaction by examining the capacity of the ciliate to form a stable association with algae when the ciliate is exposed to puromycin (PURO) or cycloheximide (CYC) during the first 1–3 h of algal insestion. Cycloheximide (100 μg/ml) blocked algal but not ciliate growth and protein synthesis while PURO (250 μg/ml) appeared to inhibit these processes in both Puromycin significantly inhibited the infection when presented to the ciliate during the first hour of algal exposure and had little effect when added after that period. Inhibition of ciliate, as compared to the alga, protein synthesis appears to be significant in relationship to those processes leading to infection, as CYC when presented during the first hour of algae‐ciliate exposure has no inhibitory effects. Experiments on algal sugar secretion and ciliate ingestion of algae indicated that neither process was significantly affected by these inhibitors. These results point to a need for host protein synthesis during the initial phase of ingestion of algae which appears to be important to establishment of the symbiotic association.
A Monoclonal Antibody Against a Symbiont‐Synthesized Protein in the Cytosol of Symbiont‐Dependent Amoebae1
Authors: KIM H. B. , JEON K. W. 
Published: May 2007

ABSTRACTA monoclonal antibody was obtained against a 29‐kD polypeptide in the cytosol of a symbiont‐bearing strain (xD) of Amoeba proteus and was used to determine the distribution of the antigen in amoebae. The 29‐kD polypeptides (xD protein) are produced by bacterial endosymbionts that are necessary for the survival of host xD amoebae. Results of indirect immunofluorescent and electron‐microscopic immunogold‐labeling studies showed that the xD protein was present diffusely in the amoeba cytoplasm as well as in the symbiotic bacteria. The native protein containing 29‐kD polypeptides was purified using an immunoaffinity column prepared with the monoclonal antibody and its molecular weight was determined to be 87,000.
Seasonal Abundance of Acanthamoeba rhysodes (Singh, 1952) (Protozoa: Gymnamoebia) in a Mangrove Litter‐Soil Ecosystem of Gangetic‐Estuary, India1,2
Authors: Bhattacharya Amal , Ghosh Mrinal , Choudhury Amalesh 
Published: May 2007

ABSTRACTAcanthamoeba rhysodes has been found to be a predominant intertidal benthic gymnamoeba in the mangrove ecosystem of Sundarbans of lower deltaic Bengal, facing the Bay. The sampling zones under study were the highest high tide regions, with characteristic mangrove litter‐soil, inundated twice per month during the highest ebb of spring tide. Population abundance of this species, both in its trophic and cystic forms in the three distinct seasonal periods of pre‐monsoon (March to June), monsoon (July to October), and post‐monsoon (November to February) has been surveyed for over two years. These seasonal periods affect the physico‐chemical parameters of the habitat substrata, including temperature, pH, and salinity. It has been found that the overall number of organisms per gram of soil attains peak value during the monsoon period. This value comes down in post‐monsoon samples and is the least in pre‐monsoon ones.
Purification of African Trypanosomes Can Cause Biochemical Changes in the Parasites1
Authors: Lonsdale‐Eccles John D. , Grab Dennis J. 
Published: May 2007

ABSTRACTBloodstream forms of African trypanosomes are routinely purified from blood components by a combination of centrifugation and chromatography on DEAE cellulose at pH 8.0, Here we report that the nonphysiological conditions used for DEAE chromatography of the parasites result in changes in the ATP levels of the trypanosomes and an enhanced release from the parasites of proteins such as variable surface glycoprotein, peptidase, and phospholipase. Some of these changes can be reduced by the addition of nucleosides to the elution buffer and, after the elution of the parasites, by immediate readjustment of the external pH to the normal physiological level of blood (pH 7.4).
Molecular Biology of the Genes for Immobilization Antigens in Paramecium1
Authors: Preer John R. , Preer Louise B. , Rudman Bertina , Barnett Audrey 
Published: May 2007

ABSTRACTSeveral genes for surface antigens of the Paramecium aurelia complex of species have been isolated. In addition lo known deletions of the 51A gene, we have obtained deletions involving the 51B gene and have developed a procedure for obtaining deletions of additional genes. Both Mendelian and non‐Mendelian deletions of both the A and B genes have been found. In the non‐Mendelian deletions the genes are present in the micronuclei and absent in the macronuclei. Processing of micronuclear DNA into new macronuclear DNA at conjugation and autogamy is under the control of the old macronucleus, and newly forming macronuclei become exactly like the old. Thus in the non‐Mendelian mutants, macronuclei have a specific antigen gene deleted and also are impaired in their ability to direct normal DNA processing at the next conjugation or autogamy. These cases, along with others, show that this system of macronuclear control is a fundamental feature of ciliate genetics. The sequence of the 51A and 51C genes is described and compared with the 156G and 51H genes obtained by others. The 51A and 156G genes are remarkably similar while 51Cand 51H are rather different. No introns or pseudogenes have been observed. Some, possibly all, of the genes are on the ends of chromosomes. Characteristic upstream and downstream sequences adjacent to the coding portions of the genes are given. The sequences UAA and UAG are preferred over CAA and CAG for glutamine while UGA is the true stop codon.
Micronuclear Organization of Macronuclear Genes in the Hypotrichous Ciliate Oxytricha nova1
Authors: Klobutcher Lawrence A. 
Published: May 2007

ABSTRACTDuring it life cycle, the hypotrichous ciliate Oxytricha nova transforms a copy of its chromosomal micronucleus into a transcriptionally active macronucleus that contains linear, gene‐sized DNA molecules. The process of macronuclear development involves chromosome fragmentation as well as elimination of large amounts of the micronuclear genome. To obtain a better understanding of the molecular details of this process, the micronuclear organization of a number of cloned macronuclear DNA molecules has been examined. These studies indicate two additional types of DNA rearrangement occur during, development. Specific sequences are added to the ends of macronuclear DNA molecules during development while other short blocks of sequences are removed from the bodies of macronuclear DNA molecules by a nucleic acid breakage and joining process. These studies also indicate that the precursors of macronuclear DNA molecules are clustered in the micronuclear chromosomes and imply the existence of large stretches of developmentally eliminated DNA.
Gamone Production in Large‐Scale Cultures of Euplotes octocarinatus1
Authors: KUSCH JÜRGEN , HECKMANN KLAUS 
Published: May 2007

ABSTRACTWe report a method that allows us to grow and maintain the freshwater ciliate Euplotes octocarinatus in large quantities. Frequent exchange of culture fluid proved more effective than aeration in obtaining high cell densities (4200 cells/ml) and reasonable doubling times in large‐scale cultures. For harvesting gamone 1, the cell density was raised to 10,000 cells/ml. Under these conditions, the cells continued to produce and secrete gamone; they were slightly starved, but they no longer divided. Cell‐free fluid with a steady and relatively high yield of gamone was obtained from two such cultures over a period of five months. We isolated gamone 1 also from cell homogenates and compared it with secreted gamone 1, but found no differences in the gamones from these two sources.
Plasmodium falciparum: Association with Erythrocytic Superoxide Dismutase1
Authors: ARIAS ARIEL E. , WALTER ROLF D. 
Published: May 2007

ABSTRACTLevels of superoxide dismutase (SOD) activity and its properties in Plasmodium falciparum‐infected erythrocytes, isolated parasites, and noninfected erythrocytes were studied. A higher specific activity was found in P. falciparum‐infected erythrocytes compared to noninfected erythrocytes, resulting from the lower protein content of infected cells and not enzyme synthesis by the parasite, as the superoxide dismutase activity expressed per number of cells was decreased. Superoxide dismutase from noninfected erythrocytes and isolated P. falciparum parasites showed similar sensitivities to various inhibitors and had identical molecular weights and electrophoretic mobilities. These results support the hypothesis of uptake and use of the erythrocytic SOD enzyme by the parasite as a possible mechanism of defense against oxidative stress.
Development of Hammondia heydorni in Cultured Bovine and Ovine Cells1
Authors: SPEER C. A. , DUBEY J. P. , BLIXT J. A. , BLAGBURN B. 
Published: May 2007

ABSTRACTSporozoites were excysted from oocysts of Hammondia heydorni obtained from a naturally‐infected dog and inoculated into monolayer cultures of bovine pulmonary artery endothelial cells (CPA), Madin‐Darby bovine kidney (MDBK) cells, bovine monocytes (M617), or ovine monocytes (WOMO). Sporozoites penetrated all four cell lines and underwent asexual reproduction by endodyogeny (as determined by electron microscopy) to form cyst‐like structures at four to nine days after sporozoite inoculation (DAI). At 4–10 DAI, considerably more zoites were harvested from M617 cultures (80.1 times 106 zoites) than from CPA (17.4 times 106), MDBK. (47.3 times 106), and WOMO (53.5 times 106). Little or no parasite multiplication occurred at 10–16 DAI. Zoites harvested at 7 DAI and transferred to freshly prepared cultures did not penetrate cells nor develop further.
Pathogenic and Non‐pathogenic Entamoeba: Pore Formation and Hemolytic Activity1
Authors: KELLER FOLKER , WALTER CLAUDIA , LÖHDEN ULLA , HANKE WOLFGANG , BAKKER‐GRUNWALD TILLY , TRISSL DOROTHEA 
Published: May 2007

ABSTRACTPore‐forming activity in planar lipid bilayers and liposomes of extracts from differentially pathogenic Entamoeba and the‐capacity of trophozoites and subcellular fractions to lyse human red blood cells (hrbc) were investigated. In all amebas studied, the two activities paralleled each other. They were high in E. histolytica irrespective of the virulence of the particular strain, but low in non‐pathogenic E. histolytica‐like amebas of human origin as well as in E. invadens, which is pathogenic for reptiles, and in E. moshkovskii isolated from sewage. We conclude that the capacities to insert pores and to lyse are not sufficient for virulence although they may be necessary.The subcellular distribution of the hemolytic activity of E. histolytica and its sensitivity to a variety of inhibitors and activators differ from those of other known amebic cytotoxic activities including pore formation. Therefore, there may be an additional constituent of E. histolytica involved in the cytotoxicity of the parasite.
Malaria Sporozoites Leave Behind Trails of Circumsporozoite Protein During Gliding Motility1
Authors: STEWART MICHAEL J. , VANDERBERG JEROME P. 
Published: May 2007

ABSTRACTAs Plasmodium sporozoites undergo gliding motility in vitro, they leave behind trails of circumsporozoite (CS) protein that correspond to their patterns of movement. This light microscopic observation was made using Plasmodium berghei sporozoites, a monoclonal antibody (MAb H4) directed against the immunodominant repetitive epitope of the CS protein of P. berghei, and an immunogold‐silver staining (IGSS) technique. Sporozoites pretreated with agents that inhibit sporozoite motility and invasiveaess did not produce trails. Sporozoites that glided on microscope slides coated with MAb H4 left behind considerably longer CS prolem trails than those on uncoated slides, and the staining of these trails was more intense. The fact that the CS protein is an exoantigen continuously released as trails by motile sporozoites, together with our previous finding that anti‐CS protein antibodies inhibit sporozoite motility, strongly suggests that the CS protein plays a role in gliding motility. The sensitive IGSS technique used in this study may be a useful tool in the study of the translocation of surface proteins during gliding of other apicomplexans, other protists, and bacteria.
Encephalitozoon cuniculi: Quantitation of Parasites and Evaluation of Viability1
Authors: PETERSON NORMAN , LIU JIUAN , SHADDUCK JOHN 
Published: May 2007

ABSTRACTTwo methods (manual and automated) for quantitation of viable versus dead Encephalitozoon cuniculi are reported. The manual method uses ethidium bromide and acridine orange to stain dead and viable organisms, respectively. The stained organisms are visually differentiated with the aid of a fluorescence microscope. The automated method uses propidium iodide to stain dead parasites, which are differentiated from viable unstained parasites with the aid of a flow cytometer. An automated cell counter (Coulter Counter) was used to count rapidly large numbers of samples and to improve the sensitivity of counting low concentrations of parasites. These methods will enhance investigators' abilities to conduct quantitative experiments on host defense mechanisms against E. cuniculi.
Cross‐Transmission of Eimeria spp. (Protozoa, Apicomplexa) of Rodents—A Review
Authors: LEVINE NORMAN D. , IVENS VIRGINIA 
Published: May 2007

ABSTRACTA total of 169 cross‐transmission attempts has been made with 44 (11.8%) of the 372 named species of Eimeria of rodents. Of these, 161 were rodent‐to‐rodent, 6 rodent‐to‐lagomorph, and 1 each rodent‐to‐carnivore and rodent‐to‐bird. None of the last three categories was successful. In the rodent‐to‐rodent combinations, 39 (80%) of the 49 attempts to transmit a coccidian species from one rodent species to another of the same genus were successful, and only 14 (12.5%) of the 112 attempts to transmit a coccidium to a rodent of a different genus were successful. Eight of the successful attempts were with E. chinchillae, which was the only truly euryxenous species of Eimeria in the group. Two successful attempts were between the closely related rodent genera Spermophilus and Cynomys, and two were both of E. separata from Rattus norvegicus to some genetic strains but not to others of Mus musculus. One attempt with E. vermiformis from Mus musculus to Rattus norvegicus required treatment of the rat with the immunosuppressant dexamethasone to succeed. More cross‐transmission studies are needed to determine the host‐spectra of the species of Eimeria and other coccidian genera, and to determine the roles of genetics and immunosuppression in their transmission.
Superiority of Hemoglobin to Hemin for Cultivation of Leishmania tropica Promastigotes in Serum‐Free Media1
Authors: GHOLAMHOSSEINIAN A. , VASSEF A. 
Published: May 2007

ABSTRACTLeishmania tropica promastigotes grew slowly but could be maintained for long periods in serum‐free hemin‐containing media formulated previously for other Leishmania species or in slightly simplified versions of these media. Replacement of hemin in the medium by hemoglobin resulted in a much longer log phase and a significant reduction in the doubling time. Cell counts in cultures started at 1 times 105 cells/ml increased 400‐fold in less than 140 h in the hemoglobin‐containing media. These media also proved suitable for growing L. donovani and L. enriettii promastigotes.