bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation and Partial Characterization of Mutants of the Trypanosomatid Crithidia fasciculata and Their Use in Detecting Genetic Recombination1
Authors: Glassberg J. , Miyazaki L. , Rifkin M. R.
Published: May 2007

Crithidia fasciculata was used as a model trypanosomatid to study the possible existence of genetic recombination in this group of protozoa. The approach was based on the ability to select a variety of mutants on agar plates. Following mutagenesis of wild type cells by nitrosoguanidine or ethylmethanesulfonate, stable mutant phenotypes were obtained. These included mutants resistant to the drugs actinomycin D, 6‐azauracil, 6‐azauridine, and 5‐fluorouracil, auxotrophs and colony morphology mutants. Following mixed growth of pairs of drug‐resistant mutants on selective media, isolates exhibiting stable recombinant phenotypes were obtained. The data presented suggest that 1) Crithidia undergoes some type of genetic recombination and 2) Crithidia must be diploid at some time during this process.
Exoantigens of Trypanosoma cruzi. I. Conditions for Their Detection and Immunogenic Properties in Experimental Infections1
Authors: Moretti Edgardo R. A. , Basso Beatriz , Vottero‐Cima Elsa
Published: May 2007

ABSTRACT Exoantigens of Trypanosoma cruzi were produced in experimentally infected BALB/c mice. The exoantigens were detected by the counterimmunoelectrophoresis method (CIE), with antisera raised in rabbits by immunization with total homogenates of culture forms of ***T. cruzi in plasma from ***field animals obtained by centrifugation and filtration. Control experiments indicated that exoantigens are not somatic components of T. cruzi leaked during the preparative procedure. Exoantigens were detected in male and female mice, 11‐90 days old, between 6 and 60 days of infection, and in all mice with patent parasitemia. After 13 days of infection, mice developed antibodies to exoantigens; by CIE up to three populations of antibodies were revealed in different groups of animals. In mice between 13 and 60 days of infection, the coexistence of exoantigens and homologous antibodies was also observed. The exoantigens are not strain specific since a cross reactivity between antigens from three strains of T. cruzi (Tulahuén, Higueras, and Alejandro) was seen. Finally, the presence of antibodies to exoantigens in humans with chronic Chagas’ disease was demonstrated.
Entamoeba histolytica and E. invadens: Sulfhydryl‐Dependent Proteolytic Activity1
Authors: Vila Eva E. A. , SÁnchez‐Garza Mireya , Calderón Jesús
Published: May 2007

Sodium dodecyl sulfate (SDS) and 2‐mercaptoethanol (2‐ME) activated proteolytic enzymes present in extracts of Entamoeba histolytica and E. invadens; SDS (0.5%) and 2‐ME (1.4 and 715 mM) doubled the enzymatic activity when assayed on a stained insoluble substrate. Urea (4 M) did not reduce this activity, suggesting that amebic proteases are stable in the above denaturant conditions. Specific reagents for sulfhydryl (‐SH) groups completely inhibited proteolytic activity regardless of pH. Inhibition with alkylating agents, such as N‐ethylmaleimide and iodoacetamide, was reversed with 715 mM 2‐ME as was also observed with papain. We conclude from these results that the main proteolytic enzymes contained in extracts of E. histolytica and E. invadens are dependent on free thiol groups.
Structural Bases of the Cytolytic Mechanisms of Entamoeba histolytica1
Authors: Martinez‐Palomo Adolfo , Gonzalez‐Robles Arturo , Chavez Bibiana , Orozco Esther , Fernandez‐Castelo Silvia , Cervantes Arnulfo
Published: May 2007

The cellular bases of the powerful cytolytic activity of the human protozoan parasite Entamoeba histolytica were explored by studying the effect of the virulent strain HM1:IMSS on epithelial monolayers of MDCK cells using a combination of time‐lapse microcinematography and transmission and scanning electron microscopy. Early alterations of the epithelial cell membranes were detected by measuring changes in the transepithelial electrical resistance of MOCK monolayers mounted in Ussing chambers. The aggressive mechanism of E. histolytica trophozoites was found to be a complex, multifactorial phenomenon that included hit‐and‐run damage to the plasma membrane of effector cells mediated through contact, phagocytosis of lysed or apparently intact, but detached, MDCK cells, and inlracellular degradation of ingested cells. Following contact with amebas, the epithelial monolayers showed a pronounced lowering of transepithelial resistance, opening of tight junctions, distortion of microvilli, surface blebbing, and the presence of minute focal discontinuities in the plasma membrane. There was no evidence of amebic exocytosis, membrane fusion, or junction formation between the parasite and host plasma membranes. Although modifications in the epithelial cell membranes usually preceded lysis, the cytolytic activity of the parasite did not exclusively involve damage to the plasma membrane of the cultured host cells but also was mediated by avid phagocytosis, the displacement and separation of neighboring cells by means of pseudopodial activity, and the “pinching‐off” of the peripheral cytoplasm of epithelial cells.
Isolation of Naegleria australiensis from an Oklahoma Lake1
Authors: JOHN D. T. , DE JONCKHEERE J. F.
Published: May 2007

Eight isolates of Naegleria australiensis were obtained from a small lake in Tulsa, Oklahoma. The eight strains were isolated during the hot summer months of July through September, when water temperatures ranged from 27 to 33°C. All eight isolates were pathogenic for mice. The mean time to death for mice was 10 days (range 6–13 days). This pathogenic free‐living ameba has not before been reported from the United States or the Western Hemisphere.
Isospora dawadimiensisn. sp. (Protozoa: Eimeriidae) from the Jerboa (Jaculus jaculus) in Saudi Arabia
Authors: KASIM AHMED A. , SHAWA YASER R. AL
Published: May 2007

Isospora dawadimiensisn. sp. is described from the jerboa,Jaculus jaculus, from Dawadimi, Saudi Arabia. Sporulated oocysts ofI. dawadimiensisn. sp. were ovoidal or nearly subspherical 22–26.5 times 20.5–22 μm (24.4 times 21.4 μm). Oocyst wall had one layer. Micropyle, oocyst residuum, and polar granule were absent. Sporocysts were ellipsoid 12–16.5 times 9–10.5 μm (14.6 times 9.9 μm). Sporocyst residuum was present. The sporocysts lack a Stieda body. Sporozoites 8–11 times 2–3 μm (10 times 2.6 μm) were sausage‐shaped, slightly curved, and tapered at one end.
Nutritional Requirements of Plasmodium falciparum in Culture. III. Further Observations on Essential Nutrients and Antimetabolites1
Authors: GEARY TIMOTHY G. , DIVO ALAN A. , BONANNI LINDA C. , JENSEN JAMES B.
Published: May 2007

In a semi‐defined minimal medium for cultivation of Plasmodium falciparum, ribose, mannose, fructose, galactose, and maltose could not replace glucose. Hypoxanthine was the preferred purine source for the parasite over adenine, guanine, inosine, adenosine and guanosine although all supported growth equally. Inhibitors of nucleoside uptake had low potency in killing the parasites but depressed incorporation of [3H]adenosine more than [3H]hypoxanthine. Glutamate could not be replaced by 5‐oxoproline, indicating that the γ‐glutamyl transferase pathway for amino acid uptake is probably not found in this organism. Adenine, nicotinamide, and orotic acid could not supplement glutamine‐deficient medium. The pyridoxine antagonists isoniazid and 4‐deoxypyridoxine were reversed by amino acid supplementation, suggesting that transaminases may be targets of these drugs. Orotic acid, but not glutathione or its amino acid components, partially reversed the effects of 8‐methylamino‐8‐desmethyl riboflavin. Thus, the flavin enzyme, dihydroorotic acid dehydrogenase, but not glutathione reductase, appears to be a target of this riboflavin antagonist. Five biotin antagonists had no significant activity. The choline antagonist 2‐(tert‐butylamino)ethanol and thiamin uptake inhibitors had nonspecific inhibitory effects, which were not reversed by the respective target vitamin. Buthionine sulfoximine and methionine sulfoximine, inhibitors of glutathione synthesis, had significant oxygen‐dependent toxicity. Six sulfonamides showed marked variation in potency and efficacy. Sulfathiazole and sulfadoxine were reversed differentially by p‐aminobenzoic acid, folic acid, and folinic acid. Folinic acid was more effective than folic acid at reversing the toxicity of the dihydrofolate reductase inhibitors aminopterin and pyrimethamine; p‐aminobenzoic acid had no effect.
RNA and Protein Synthesis During Meiotic Prophase in Tetrahymena thermophila1
Authors: MARTINDALE DUANE W. , ALLIS C. DAVID , BRUNS PETER J.
Published: May 2007

Tetrahymena is one of the few organisms from which large amounts of precisely staged meiotic material can be obtained. We took advantage of this fact to monitor RNA and protein synthesis during meiosis. The rate of total protein synthesis as well as the synthesis of the majority of heavily labeled conjugation‐specific polypeptides (monitored by high resolution two‐dimensional gel electrophoresis) was maximal during meiotic prophase. We therefore cloned cDNAs corresponding to genes active during this time. The mRNA levels of three conjugation‐specific genes (pC1, pC2, and pC7) and one conjugation‐induced gene (pC3) were followed by using the corresponding labeled cDNAs to probe RNA isolated from different times during mating that was also followed cytologically. Synthesis of the conjugation‐specific mRNAs was maximal just prior to maximum crescent stage (pachytene). Evidence is presented for transcription by the normally inactive micronucleus just prior to the maximum crescent stage, confirming an earlier report. The significance of these results is discussed.
Morphology of Giardia agilis: Observation by Scanning Electron Microscopy and Interference Reflexion Microscopy1
Authors: FEELY DENNIS E. , ERLANDSEN STANLEY L.
Published: May 2007

The flagellated protozoan, Giardia agilis, was isolated from tadpole small intestine and examined by scanning electron microscopy and interference reflexion microscopy. The general morphology of the G. agilis trophozoite is similar to G. muris and G. duodenalis, but with modifications that reflect its elongated form. Interference reflexion microscopic analysis of attachment of G. agilis reveals a pattern of focal contacts by the lateral crest of the ventral disc, the ventrolateral flange, the lateral shield, and by numerous microvillus‐like appendages found along the lateral border of the trophozoite. The pattern of focal contacts was observed to be dynamic; trophozoites were observed to make and break the focal contacts in a relatively short time and to glide along the surface of the substratum without breaking focal contacts.
Ultrastructure of Cryptosporidium parvum Oocysts and Excysting Sporozoites as Revealed by High Resolution Scanning Electron Microscopy1
Authors: REDUKER DAVID W. , SPEER C. A. , BLIXT JOHN A.
Published: May 2007

Cryptosporidium parvum oocysts isolated from calf feces were examined by scanning electron microscopy during excystation. Intact C. parvum oocysts were spheroid to ellipsoid, ≅3.5 × 4.0 μm, with length: width ratio = 1.17. The oocyst wall had a single suture at one pole, which spanned 1/3 to 1/2 the circumference of the oocyst. During excystation the suture dissolved, resulting in a slit‐like opening, which the sporozoites used to exit the oocyst. Sporozoites were 3.8 times 0.6 μm and had a rough outer surface.
Holospora elegans‐Infected Micronuclei of Paramecium caudatum Still Serve a Function During Vegetative Life1
Authors: MIKAMI KAZUYUKI , GÖRTZ HANS‐DIETER
Published: May 2007

The fission rate of Paramecium caudatum cells infected with the micronucleus‐specific bacterium Holospora elegans was examined before and after elimination of the micronucleus. Uninfected cells, micronucleate and amicronucleate, were used as controls. Emicronucleation of Holospora elegans‐infected cells causes a decrease of fission rates, as is observed after emicronucleation of uninfected cells. This is taken as an argument that infected micronuclei still serve a function for the vegetative life of P. caudatum.
The Extent of Algal and Bacterial Endosymbioses in Protozoa1,2
Authors: LEE JOHN J. , SOLDO ANTHONY T. , REISSER WERNER , LEE MONICA J. , JEON K. W. , GÖRTZ HANS‐DIETER
Published: May 2007

Long neglected has been the extensive and more or less intimate association of protozoa with a wide variety of other cells, either prokaryotic or eukaryotic in nature. Yet study of such relationships can provide important information concerning certain basic aspects of cellular evolution in general. A survey is offered here of the whole range of such symbiotic associations (i.e. with species of protozoa serving as hosts) with the purposes of drawing attention to the exciting possibilities of such research and of reviewing significant findings made to date. Because of the vastness of the overall field, examples and discussion are primarily limited to consideration of the following major studies: methanogenic bacteria in certain ciliates, bacterial endosymbionts of the large freshwater amoebaPelomyxa palustris(itself an amazing organism from an evolutionary/phylogenetic point of view), the rod‐shaped bacteria found inAmoeba proteus, the “Greek‐letter” prokaryotes ofParameciumspecies, the xenosomes (sensu stricto) of the marine scuticociliateParauronema acutum, and the diverse algal endosymbionts of similarly diverse protozoan taxa–ciliates, flagellates, radiolarians, acantharians, and foraminifera.
Reproducing Singlets with an Inverted Oral Apparatus in Glaucoma scintillans (Ciliophora, Hymenostomatida)1
Authors: SUHAMA MIKIO
Published: May 2007

A fragment with only an abnormal oral apparatus (OA) was obtained by operation from a doublet of Glaucoma scintillans possessing one normal and one abnormal OA. This singlet could reproduce and produced a cell line. Singlets frequently possessed an inverted OA, whose antero‐posterior axis was rotated 180°. This inversion of the OA has been perpetuated through a considerable number of generations. Oral replacement commonly occurred in singlets with an abnormal OA regardless of growth phases of a culture. The position of the contractile vacuole pore, the direction of curvature of ciliary rows surrounding the OA, and the organization of postoral ciliary rows were mirror‐images of those of a normal singlet.
Polyphenol Oxidase Produced During Encystation of Acanthamoeba castellanii
Authors: SYKES DONALD E. , BAND R. NEAL
Published: May 2007

Acanthamoeba castellanii has a phenol oxidase activity that is believed to be a laccase. Enzyme activity was found in the outer cyst wall, in the cytoplasm of encysting amoebae and in the encystment medium. Encystment procedures were modified to promote an increase in the amount of soluble enzyme secreted during encystation. Acanthamoeba polyphenol oxidase has a pH optimum of 6.0 and a Km value of 0.21 mM with dihydroxyphenylalanine. The enzyme does not oxidize tyrosine, and it is inhibited by chloride but not by inhibitors of peroxidase. Its synthesis coincides with encystation. and known inhibitors of polyphenol oxidase prevent encystation. Polyphenol oxidase may have a role in making the cyst resistant to mechanical and chemical breakdown.
Cytoplasmic Inheritance of Temperature Sensitivity in a Wild Stock of Paramecium primaurelia1
Authors: NYBERG DENNIS
Published: May 2007

ABSTRACT. One stock, GBC, has a maximum temperature of growth about 5°C lower than other recently collected stocks of Paramecium primaurelia. The resistant stocks (R) are able to grow continuously at 35°C while the sensitive stock (S) cells die within 48 h. The F1s of R x S crosses exhibited a cytoplasmic pattern of inheritance and all F2‐by‐autogamy lines derived from the S cytoplasmic parent are sensitive. The F2‐by‐autogamy lines cytoplasmically descended from the R parent were predominantly (93%) R in the initial assay. Upon reinvestigation one year later, only 64% of these lines were R, 9% were S, and 27% had a new phenotype, weak (W), intermediate between R and S. Backcrosses of W lines to both R and S strongly suggest that the W lines have normal cytoplasm (i.e. R) but also have nuclear gene(s) for temperature sensitivity that are derived from the original S stock. The delayed manifestation of the W phenotype is not understood.
Combined Action of Cadmium and Selenium on Two Marine Dinoflagellates in Culture, Prorocentrum micans Ehrbg. and Crypthecodinium cohnii Biecheler1
Authors: PREVOT P. , SOYER‐GOBILLARD M.‐O.
Published: May 2007

ABSTRACT. The combined action of cadmium and selenium was investigated in two unicellular marine phytoplankton organisms, Prorocentrum micans Ehrbg. and Crypthecodinium cohnii Biecheler, in culture. When present simultaneously in low concentrations, the toxicity of Cd and Se is decreased (antagonism) whereas if one of these elements is present at high concentration, especially for a long period, their toxicity is increased (synergism) more than if they were separate. This interaction affected cell organelles in the following ways: vacuolation, development of chloroplast pyrenoids, and elicitation of lipid vesicles, starch vesicles, giant mitochondria, and lysosomes. Possible competition between these two elements for binding sites is discussed.
Cytochrome‐Free Mitochondria of an Anaerobic Protozoan—Blastocystis hominis
Authors: ZIERDT CHARLES H.
Published: May 2007

ABSTRACT. Isolated mitochondria of the anaerobic protozoan Blastocystis hominis were subjected to spectral analysis, color, catalase, and peroxidase tests and found to be completely negative for cytochrome enzymes, catalase, and peroxide. Based on the absence of cytochrome enzymes, the possible evolution of B. hominis mitochondria from anaerobic bacteria is postulated.
Eimeria tenella: Parasite‐Specific Incorporation of 3H‐Uracil as a Quantitative Measure of Intracellular Development1
Authors: SCHMATZ DENNIS M. , CRANE MARK S. J. , MURRAY P. KEITH
Published: May 2007

ABSTRACT. An assay has been developed using parasite‐specific incorporation of 3H‐uracil to assess the intracellular growth of Eimeria tenella in vitro. As shown by both scintillation counts and autoradiography, 3H‐uracil was incorporated specifically into intracellular parasites from the onset of infection and continued throughout development of the first generation schizonts. Mature schizonts and first generation merozoites did not continue to incorporate additional 3H‐uracil, indicating that RNA synthesis had halted in these stages. Based on these findings, a semi‐automated microscale uracil incorporation assay was developed to determine parasite viability. This method should be useful for biochemical studies with intracellular parasites and for screening compounds for anticoccidial activity. The ease, rapidity, and quantitative nature of this assay contrasts favorably with standard morphometric approaches of determining parasite development. In addition, parallel studies using host cell incorporation of 3H‐uridine have been introduced as a method of determining whether antiparasitic activity is direct or indirect in relation to effects on the host cell.
Use of Protozoan Communities to Predict Environmental Effects of Pollutants1
Authors: YUN‐FEN SHEN , BUIKEMA A. L. , YONGUE W. H. , PRATT JAMES R. , CAIRNS J.
Published: May 2007

ABSTRACT. This study compared the response of protozoan communities colonizing artificial substrates to complex effluents in laboratory microecosystems and validated laboratory predictions using similar sampling methods in the field. Sampling stations were established on a small stream receiving heavy metal and sewage treatment plant effluents. Water from each station was used as a test medium to test the colonization of polyurethane foam artificial substrates in laboratory microecosystems. The heterotrophic index (HI), the ratio of total community biomass to chlorophyll biomass, was also measured. Field colonization trials and HI determinations were carried out at each sampling station. There was a strong negative relationship between the number of species colonizing artificial substrates and the total metal concentration of the water at each station; protozoan colonization was severely depressed at the highest metal concentrations (>400 μg/liter) and recovered at downstream stations where dilution had taken place. The HI differentiated stations receiving high heavy metal concentrations in the field from those recovering from heavy metal influences. Effect concentrations based on laboratory experiments predicted that the concentration of total heavy metal that would produce a 5% decrease in species number (EC5) was 18 μg/liter, approximately the background concentration found in the stream studied. These experiments demonstrated that laboratory microecosystems or microcosms can be used to predict effects in the field accurately.
Food Vacuole Morphology and Membrane Retrieval in the Microstomal Form of Tetrahymena vorax1
Authors: MISLAN TIMOTHY W. , SMITH‐SOMERVILLE HARRIETT E.
Published: May 2007

ABSTRACT. After formation, food vacuoles in the microstomal cell type of Tetrahymena vorax labeled with either India ink or cationized ferritin (CF) undergo three morphological stages during processing: an initial condensation with a size decrease, the appearance of a clear halo around the condensed marker that apparently results from expansion of the vacuole, and the disappearance of the halo region. These stages correspond generally to three of the four stages described previously for Tetrahymena. Fusion of older vacuoles prior to egestion may represent a fourth stage in vacuole processing. The developing vacuole has small coated regions of the membrane; two populations of vesicles, small coated vesicles and larger vesicles with electron‐dense cores, are adjacent to it. During the initial condensation, tubular invaginations with CF project from the vacuole. After the disappearance of the halo, much of the vacuolar surface appears to be multilayered with extensive folds containing CF. Labeled flattened or curved disks and closed rings occur in the cytoplasm often adjacent to labeled vacuoles and in the vicinity of the cytoproct. The appearance of labeled disks and rings is identical to both labeled and unlabeled vesicles adjacent to the cytopharynx, adding additional support to the hypothesis that, like Paramecium, vesicles retrieved from food vacuoles during processing as well as after fusion with the cytoproct may be reused for vacuole formation.
Cross‐Reactive Polysaccharides from Trypanosoma cruzi and Fungi (Especially Dactylium dendroides)1
Authors: SCHNAIDMAN BERENICE B. , YOSHIDA N. , GORIN P. A. J. , TRAVASSOS L. R.
Published: May 2007

ABSTRACT. Cross‐reactivity between fungal and Trypanosoma cruzi polysaccharides, owing to common residues of β‐D‐galactofuranose, β‐D‐galactopyranose, and α‐D‐mannopyranose, was demonstrated by using a) rabbit immune sera against T. cruzi epimastigotes and b) sera from patients with Chagas’disease. Several chagasic (Ch) sera precipitated partly purified galactomannans from Aspergillus fumigatus and from T. cruzi epimastigotes and also the galactoglucomannan from Dactylium dendroides. Reaction of one Ch serum with T. cruzi galactomannan (GM) was completely inhibited by synthetic β‐D‐Galf‐(1 → 3)‐Me α‐D‐Manp, and that of another Ch serum with a purified D. dendroides galactoglucomannan (GGM) was partly inhibited by (1 → 6)‐linked (81%) or by (1 ‐ 3)‐linked (33%) β‐D‐Galf‐Me α‐D‐Manp. The β‐D‐Galf‐(1 → 3)‐α‐D‐Manp epitope was present in both T. cruzi and D. dendroides polysaccharides. Rabbit anti‐T. cruzi antisera precipitated A. fumigatus GM, T. cruzi antigenic extracts containing the lipopeptidophosphoglycan (LPPG), T. cruzi alkali‐extracted GM, a synthetic GM, and D. dendroides GGM. Weak reactivities were obtained for a Torulopsis lactis‐condensi GM containing β‐D‐Galp terminal residues and for baker's yeast mannan with α‐D‐Manp‐(1 ‐ 3)‐α‐D‐Manp‐(1‐ → 2)‐α‐D‐Manp‐(1 → 2) side chains. An anti‐LPPG rabbit serum precipitated D. dendroides GGM—a reaction inhibited (82%) by β‐D‐Galf‐(1 → 3)‐Me α‐D‐Manp and, less efficiently, by a (1 → 5)‐linked β‐D‐Galf‐tetrasaccharide. Sera from mice immunized with D. dendroides whole cells reacted with CL‐strain trypomastigotes as shown a) by indirect immunofluorescence, b) by a Staphylococcus adherence test, but were not lytic. Mice immunized with D. dendroides were not protected against a challenge with virulent T. cruzi trypomastigotes.
Isolation and Characterization of a Neutral Glycosphingolipid from the Epimastigote Form of Trypanosoma mega1
Authors: VERMELHO A. B. , HOGGE L. , BARRETO‐BERGTER E.
Published: May 2007

ABSTRACT. A glycosphingolipid fraction from Trypanosoma mega was isolated after acetylation and was further purified on a silicic acid column. Final purification was by preparative thin‐layer chromatography. The carbohydrate components of the glycolipid were fucose and galactose in approximately equimolar amounts. The neutral glycolipid of T. mega has a sphingosine base composition that consists of sphingosine and traces of dihydrosphingosine. Fatty acids forming amide groups with the sphingosine bases were analyzed by gas‐liquid chromatography‐mass spectrometry and are a mixture of normal and α‐hydroxy fatty acids. Normal C16:0, C18:0, and 2‐hydroxy C18:0 are the predominant fatty acids.
Polyamine Depletion Following Exposure to DL‐α‐Difluoromethylornithine Both In Vivo and In Vitro Initiates Morphological Alterations and Mitochondrial Activation in a Monomorphic Strain of Trypanosoma brucei brucei
Authors: GIFFIN BRUCE F. , McCANN PETER P. , BITONTI ALAN J. , BACCHI CYRUS J.
Published: May 2007

ABSTRACT. DL‐α‐difluoromethylornithine (DFMO), a specific irreversible inhibitor of ornithine decarboxylase (ODC), rapidly depletes cells of intracellular putrescine. When administered to animals and humans, DFMO cures acute infections of trypanosomiasis. In order to determine if the mechanism of drug action is related to initiation of transformation and biochemical alterations subsequent to polyamine depletion, trypanosome morphology and mitochondrial activation were studied in a monomorphic strain of Trypanosoma brucei brucei. Exposure of trypanosomes to DFMO in vivo in infected rodents or in vitro in culture resulted in a depletion of intracellular putrescine and a cessation of cell division without specific cytotoxicity. These events were followed by a transformation of the long slender bloodstream form to a short stumpy form via an intermediate morphology. Putrescine, the product of the ODC reaction, abrogates this effect. When introduced into SDM‐79 medium, the intermediate form is capable of further transformation to an “insect” procyclic trypomastigote whereas the long slender form and short stumpy form are not. Short stumpy forms are incapable of binary fission and have lost their infectivity for the vertebrate host. In addition, the mitochondrial marker enzyme, NAD diaphorase, was found only in the short stumpy and intermediate forms. We hypothesize that the short stumpy phenotype may not be a viable stage in the natural transformation of the trypanosome from its mammalian host to the insect vector.
The Life Cycle of Cryptosporidium baileyi n. sp. (Apicomplexa, Cryptosporidiidae) Infecting Chickens
Authors: CURRENT WILLIAM L. , UPTON STEVE J. , HAYNES THOMAS B.
Published: May 2007

ABSTRACT. The life cycle and morphology of a previously undescribed species of Cryptosporidium isolated from commercial broiler chickens is described. The prepatent period for Cryptosporidium baileyi n. sp. was three days post oral inoculation (PI) of oocysts, and the patent period was days 4–24 PI for chickens inoculated at two days of age and days 4–14 for chickens inoculated at one and six months of age. During the first three days PI, most developmental stages of C. baileyi were found in the microvillous region of enterocytes of the ileum and large intestine. By day 4 PI, most parasites occurred in enterocytes of the cloaca and bursa of Fabricius (BF). Mature Type I meronts with eight merozoites first appeared 12 h PI and measured 5.0 × 4.9 μm. Mature Type II meronts with four merozoites and a large granular residuum first appeared 48 h PI and measured 5.1 × 5.1 μm. Type I meronts with eight short merozoites and a large homogeneous residuum first appeared 72 h PI and measured 5.2 × 5.1 μm. Microgamonts (4.0 × 4.0 μm) produced 16 micro‐gametes that penetrated into macrogametes (4.7 × 4.7 μm). Macrogametes gave rise to two types of oocysts that sporulated within the host cells. Most were thick‐walled oocysts (6.3 × 5.2 μm), the resistant forms that passed unaltered in the feces. Some were thin‐walled oocysts whose wall (membrane) readily ruptured upon release from the host cell. Sporozoites from thin‐walled oocysts were observed penetrating enterocytes in mucosal smears. The presence of thin‐walled, autoinfective oocysts and the recycling of Type I meronts may explain why chickens develop heavy intestinal infections lasting up to 21 days. Oocysts of C. baileyi were inoculated orally into several animals to determine its host specificity. Cryptosporidium baileyi did not produce infections in suckling mice and goats or in two‐dayold or two‐week‐old quail. One of six 10‐day‐old turkeys had small numbers of asexual stages only in the BF. Four of six one‐day‐old turkeys developed mild infections only in the BF, and sexual stages of the parasite were observed in only one of the four. All seven one‐day‐old ducks and seven two‐day‐old geese developed heavy infections only in the BF with all known developmental stages present.
Physiological Characterizations of Acanthamoeba Strains
Authors: COSTAS MENELAOS , GRIFFITHS ALAN J.
Published: May 2007

ABSTRACT. Thirty‐seven strains of Acanthamoeba are described using 69 physiological characters. The characterizations of the strains are based on quantitative estimates of growth responses which were standardized to eliminate any effects of differences in growth rates of the strains. Thirty‐six distinct patterns are generated using numerical profiles, but it is possible to distinguish within this total diversity 20 sub‐generic groups which, although not completely congruent with the morphological species, are consistent with other non‐morphological characters. Evidence is presented that Acanthamoeba is a coherent, well‐founded genus, but it is not desirable to recognize formal taxa at the sub‐generic level.
An Ultrastractural Study of the Trophozoite and Cyst Stages of Protostelium pyriformis Olive & Stoianovitch, 1969 (Eumycetozoea, Protosteliia)1
Authors: BENNETT WALTER E.
Published: May 2007

ABSTRACT. Electron microscope observations of the trophic and cyst stages of the protostelid Protostelium pyriformis Olive & Stoianovitch, 1969 indicate a perinuclear golgi‐vesicular region in the amoeboid cell. Within this region is a microtubule organizing center (MTOC) and associated microtubules which radiate into the cytoplasm. The cyst wall is revealed as having three distinct regions, certain areas of the wall possibly corresponding to exit pores. Protostelium pyriformis shares many similarities in trophic cell structure with other eumycetozoans and members of the non‐mycetozoan family Acanthamoebidae.
Characterization and Quantitation of Membrane Antigens of New World Leishmania Species by Using Monoclonal Antibodies in Western Blot and Flow Microfluorometric Assays1
Authors: WILLIAMS KRISTINA M. , SACCI JOHN B. , ANTHONY RONALD L.
Published: May 2007

ABSTRACT. Membrane‐specific monoclonal antibodies generated against promastigotes of New World Leishmania species were used in Western blot, ELISA, and flow microfluorometric assays to characterize their antigen specificity and to determine the external surface distribution of the reactive epitopes. Three major membrane antigens of molecular weight 72 KD, 55 KD, and 42 KD were identified as well as a dominant antigen that migrated as a broad band on SDS‐PAGE, corresponding to a molecular weight of 10–15 KD. By dot‐ELISA this antigen was also found to be excreted by promastigotes into their culture medium. One minor membrane antigen of 25 KD and a triplet component of 66, 58, and 56 KD were also identified. While assays performed on air‐dried promastigotes revealed the almost ubiquitous presence of the 72 KD and 55 KD antigens, indirect immunofluorescent staining of live promastigotes followed by flow cytometric analysis revealed that these antigens had no external exposure. Antibodies binding the 55 KD component were also reactive toward purified mammalian tubulin. The remaining antigens had a variable distribution on the eight isolates utilized, and these quantitative differences could be used to distinguish isolates of the Leishmania mexicana complex from those belonging to the Leishmania braziliensis complex.
The Spatial Distribution and Ecology of Zoochlorellae‐Bearing Ciliates in a Productive Pond1
Authors: BERNINGER U.‐G. , FINLAY B. J. , CANTER H. M.
Published: May 2007

ABSTRACT. The spatial distributions of five zoochlorellae‐bearing ciliate species (Euplotes daidaleos, Frontonia vernalis, Acaryophrya sp., Disematostoma bütschlii, and Stokesia vernalis) were investigated in a productive freshwater pond. The vertical profiles of all species were compared to the levels of O2, CO2, light, temperature, dissolved inorganic nitrogen, and the availability of particulate food sources. In the stratified water column, Stokesia remained close to the water surface: all other species reached peak abundance close to the oxic‐anoxic boundary. The latter behavior probably accommodated the ciliates’requirements for aerobic respiration and particulate food and their dependance on the essential resources of light and dissolved nutrients, which came from opposite directions. With the collapse of stratification, Euplotes and Frontonia returned to the sediment where they reverted to a heterotrophic nutrition although they retained some zoochlorellae. Acaryophrya and Disematostoma also became heterotrophic, but they remained evenly distributed in the water column and they lost their zoochlorellae. Stokesia disappeared, presumably because it encysted. There was some evidence for vertical spatial separation of the five species in the water column.
Inclusion Bodies in Xenosomes Purified on Percoll Gradients as Revealed by Electron Microscopy
Authors: SOLDO A. T. , BRICKSON S. A. , CASTIGLIONE G. A.
Published: May 2007

A method is described for the isolation and purification of xenosomes, intracytoplasmic bacterial symbionts of the marine hymenostome Parauronema acutum, using percoll gradients. Xenosomes isolated by this procedure retained both their ability to kill susceptible Uronema strains and to infect homologous and heterologous P. acutum strains. Unexpectedly, both killer and non‐killer xenosomes were found to contain inclusion bodies, heretofore unseen in fixed whole cell preparations, in the form of double helices, which we have termed H‐bodies. The nature and function of these bodies is unknown.
Structure and Operation of the Feeding Apparatus in a Colorless Euglenoid, Entosiphon sulcatum1
Authors: TRIEMER RICHARD E. , FRITZ LAWRENCE
Published: May 2007

Entosiphon sulcatum is a phagotrophic euglenoid. The tubular ingestion apparatus, called a siphon, is composed of three microtubular rods extending the length of the cell. Within the tube are four large striated vanes arranged much like the blades in a pinwheel. The vanes arise from the microtubular rods and curve towards the center of the feeding apparatus. Sheets of endoplasmic reticulum are positioned adjacent to each of the vanes and surround the perimeter of the apparatus. A cap, supported by a scaffold and anchored into the cytoplasm, covers the opening of the siphon. An elongate invagination of the plasma membrane is positioned adjacent to the edge of the cap and extends downward into the siphon forming the opening. The vanes converge at the anterior end of the siphon and surround the invagination. During feeding, the siphon protrudes from the cell. As the apparatus protrudes the cap is withdrawn to the side, opening the siphon. The vanes spread apart expanding the invagination of the plasma membrane into a large cavity into which ingested food particles are taken.
Transmission of Megatrypanum Trypanosomes to Cervus dama by Tabanidae1
Authors: BÖSE REINHARD , FRIEDHOFF KARL T. , OLBRICH SYLVIA
Published: May 2007

Four fallow deer, Cervus dama, became infected with Trypanosoma (Megatrypanum) sp. by oral application of triturated guts from tabanids collected in an area with deer but without any cattle; four control calves remained negative. Upon challenge with triturated guts from tabanids from an area with pastured cattle, the four calves became infected with Trypanosoma (M.) theileri. The prepatent period in deer was five days or less. Haematopota spp. and Tabanus spp. were identified as vectors of the deer trypanosomes. It is concluded that the trypanosomes of C. dama belong to a Megatrypanum species that is not identical with T. theileri.
Chemotaxis by Naegleria fowleri for Bacteria1
Authors: MARCIANO‐CABRAL FRANCINE , CLINE MICHAEL
Published: May 2007

Naegleria fowleri amebae demonstrated a chemotactic and chemokinetic response toward live cells and extracts of Escherichia coli and other bacterial species when experiments were performed using a blind‐well chemotaxis chamber. The peptide N‐formyl‐methionyl‐leucyl‐phenylalanine acted as a chemokinetic rather than a chemotactic factor for N. fowleri amebae. Competition experiments in which nerve cell extracts or bacteria were placed on either side of the filter in chemotaxis chambers resulted in increased movement towards bacteria. A scanning electron microscopy study of the interaction of N. fowleri with different bacterial species confirmed that when the amebae were near ingestible bacteria they moved toward the bacteria by pseudopod formation. Naegleria fowleri appeared to respond to bacteria by three interrelated but distinct processes: (a) chemokinesis, (b) chemotaxis, and (c) formation of food cups.
Rumen Ophryoscolecid Protozoa in the Hindgut of the Capybara (Hydrochoerus hydrochaeris)1
Authors: DEHORITY BURK A.
Published: May 2007

Rumen ophryoscolecid protozoa were observed in feces obtained from two capybara (Hydrochoerus hydrochaeris) housed at the Columbus Zoo, Columbus, Ohio. Total numbers were 58.1 times 104 and 19.0 times 104 per gram of wet feces in a male and female capybara, respectively. Four common rumen species of Entodinium were observed in the feces from both animals, with low numbers of Eudiplodinium maggii and Elytroplastron bubali also occurring in the male. Establishment of rumen ophryoscolecid ciliates in the intestinal tract of non‐ruminant herbivores has not been reported previously.
Characterization of a Neutral Aminoacyl‐Peptide Hydrolase from Naegleria fowleri1
Authors: MARCIANO‐CABRAL F. , STANITSKI SUSAN , RADHAKRISHNA V. , BRADLEY S. G.
Published: May 2007

An 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

Wild 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

This 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

An 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

Granules 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

Population 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

The 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.