bluuebunny/crossref_metadata_2025 huggingface dataset:
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

It 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

A 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

Acanthamoeba 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

Bloodstream 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

Several 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

During 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.
The Stomatogenic Process in Opercularia coarctata (Ciliophora, Peritrichida)
Authors: FERNÁNDEZ‐GALIANO DIMAS , ESTEBAN GENOVEVA , MUÑOZ AMPARO
Published: May 2007

ABSTRACT. Stomatogenesis in Opercularia coarctata has been studied in specimens treated with Fernández‐Galiano's silver impregnation method. The new buccal structures originate from the germinal row and from the parental haplokinety.
Transmission and Scanning Electron Microscopy of the Evaginative Budding Process in Heliophrya sp. (Ciliata, Suctoria)1
Authors: FOX DAVID P. , HILL BRUCE F. , SPOON DONALD M. , CHAPMAN GEORGE B.
Published: May 2007

ABSTRACT. A sessile, tentacle‐bearing protozoon, Heliophrya sp. (Suctoria, Ciliata), reproduces asexually by evaginative budding to form a ciliated swarmer, which begins metamorphosis to the adult form within 30 min of its release from the parent cell. Morphological features of embryogenesis were investigated using transmission and scanning electron microscopy and found to correspond, with certain exceptions, to the few previous reports concerning evaginative budding in suctorians. Following invagination of a portion of the pellicle to form an embryonic cavity within the parent cell, numerous kinetosomes, apparently formed de novo, organize into rows which surround the embryonic cavity and eventually develop cilia that project into the cavity. When the cavity is complete, its walls are extruded through an opening in the parent cell surface. Parent cell cytoplasm streams into the incipient swarmer, thus supplying it with at least the minimum requirement of all cytoplasmic organelles. The ciliated swarmer remains attached to its parent cell for several minutes before it detaches. A complete pellicle is formed in both parent and swarmer prior to detachment. The numerous mitochondria underlying the parent cell pellicle in the vicinity of the attachment area suggest that cross wall formation is an energy‐dependent process.
Caryocyst‐Like Host Cell Formation by Caryospora duszynskii (Apicomplexa: Eimeriidae) in Human Fetal Lung Cell Cultures1
Authors: LINDSAY DAVID S. , SUNDERMANN CHRISTINE A. , BLAGBURN BYRON L.
Published: May 2007

ABSTRACT. Sporozoites of the coccidium, Caryospora duszynskii, penetrated human fetal lung cell cultures but did not undergo asexual or sexual multiplication during a 29‐day observation period. Beginning three days postinoculation (PI), infected host cells lost their normal elongated fibroblast‐like shape and became ellipsoidal in appearance and resembled caryocysts. These caryocyst‐like infected cells were observed from 3 through 29 days PI. Sporozoites remained viable throughout the study as evidenced by motility of extracellular sporozoites in infected human fetal lung cell cultures. Results of this in vitro study suggest that some species of Caryospora may form caryocysts in secondary hosts without undergoing asexual or sexual multiplication in these hosts.
Morphology of the Cyst of Giardia microti by Light and Electron Microscopy1
Authors: FEELY DENNIS E.
Published: May 2007

ABSTRACT. Cysts of Giardia microti, isolated from feces and intestinal contents of Microtus ochrogaster, were examined by light and electron microscopy. These cysts differed morphologically from cysts of other G. duodenalis morphological types in that these cysts often contained two apparently differentiated trophozoites with mature ventral discs. Cysts more closely resembling those reported for G. lamblia and G. muris were in greater abundance in preparations made from intestinal contents and were interpreted as immature cysts. “Multiple fission” cysts, reported in G. muris and G. microti by earlier workers, were not observed; however, endosymbiotic bacteria were found in the cysts of G. microti and may have been responsible for reports of multiple fission in the cysts of Giardia.
Ultrastructural Evidence for the Presence of Bacteria, Viral‐like Particles, and Mycoplasma‐like Organisms Associated with Giardia spp.1
Authors: FEELY DENNIS E. , CHASE DAVID G. , HARDIN E. LEE , ERLANDSEN STANLEY L.
Published: May 2007

ABSTRACT. Giardia trophozoites and cysts, isolated from mammalian and avian hosts, were examined by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and by fluorescent light microscopy for the presence of microbial symbionts. Mycoplasma‐like organisms were observed on the surfaces of trophozoites isolated from the prairie vole, laboratory rat, and beaver. Intracellular bacteria were observed by TEM in the trophozoites and cysts of G. microti and by fluorescence microscopy in trophozoites and cysts of Giardia spp. isolated from beaver, muskrat, great‐blue heron, and the green heron. Trophozoites of G. muris from rat small intestine contained viral‐like particles measuring 60 nm in diameter. These observations suggest that biological associations between Giardia spp. and diverse microbes may be more common than formerly appreciated. It also raises the possibility of transmission of these apparent symbionts, via the Giardia cyst, to other mammalian hosts including man.
Gamone Production in Large‐Scale Cultures of Euplotes octocarinatus1
Authors: KUSCH JÜRGEN , HECKMANN KLAUS
Published: May 2007

We 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

Levels 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

Sporozoites 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

Pore‐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

As 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

Two 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

A 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

Leishmania 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.
Morphology and Infraciliature of Trochiliopsis australis N. Sp., Pelagohalteria viridis (Fromentel, 1876) N. G., N. Comb., and Strobilidium lacustris N. Sp. (Protozoa, Ciliophora)1
Authors: FOISSNER WILHELM , SKOGSTAD ASBJØRN , PRATT JAMES R.
Published: May 2007

Three ciliate species from Australia and Norway were examined by silver impregnation, biometry, and scanning electron microscopy. Trochiliopsis australis n. sp. (order Nassulida, family Microthoracidae) differs from the single other known species of the genus, T. opaca, by its prominent ridges on the left side, the distinctly longer anterior segment of somatic kinety 2, and by the doubled total number of kinetosomes. Pelagohalteria n. g. (order Oligotrichida, family Halteriidae) differs from Halteria by the structure of the bristle complexes, which are composed of a vertically and a horizontally oriented row of kinetosomes. Two Halteria species belong to the new genus: P. viridis (Fromentel, 1876) n. comb., which is redescribed here, and P. cirrifera (Kahl, 1935) n. comb. Strobilidium lacustris n. sp. (order Oligotrichida, family Strobilidiidae) differs from its nearest relative, S. velox, by the smooth pellicle, the absence of symbiotic green algae, and by its larger size.
Con A Binds to the Membranellar and Somatic Cilia of Stentor and to the Developing Oral Primordium During Oral Regeneration1
Authors: MALONEY MICHAEL S.
Published: May 2007

Binding sites for Concanavalin A have been located in the ciliate Stentor coeruleus by utilizing FITC‐Con A and fluorescence microscopy. When both nonregenerating and regenerating Stentor are fixed prior to FITC‐Con A exposure, FITC‐Con A binds intensely to the cilia of the membranellar band and to the somatic cilia that cover much of the cell surface. No binding is observed between the ciliary rows. The FITC‐Con A also binds to the developing oral primordia of regenerating cells. Binding of FITC‐Con A in the early stages of regeneration (prior to stage 4) appears to be less intense than that in the later stages. Additional FITC‐Con A binding appeared as a granular fluorescence in the area of the developing buccal cavity beginning at about stage 4 and disappearing around stages 6–7. The presence of α‐D‐methyl mannoside prevented the binding of FITC‐Con A to either regenerating or nonregenerating cells. If nonregenerating Stentor are exposed to FITC‐Con A prior to fixation, the binding pattern is entirely different with the fluorescence primarily in the form of random, granular patches spread over much of the cell but with no binding to either type of cilia. These results demonstrate that membrane glycoproteins capable of binding Con A are located primarily in the membranellar and somatic cilia and in the developing oral primordia during oral regeneration in Stentor. Concanavalin A binding to these sites may be involved in the Con A‐induced inhibition of oral regeneration observed in earlier studies.
Comparison of the Protein Kinase and Acid Phosphatase Activities of Five Species of Leishmania1
Authors: MUKHOPADHYAY NISHIT K. , SAHA ASISH K. , LOVELACE JAMES K. , DA SILVA ROSANGELA , SACKS DAVID L. , GLEW ROBERT H.
Published: May 2007

Promastigotes from log phase and stationary phase cultures of Leishmania donovani, L. braziliensis panamensis, L. tropica, L. major, and L. mexicana amazonensis were analyzed for their content of protein kinase and acid phosphatase activities. Cell surface, historic‐specific protein kinase activity was 1.3‐ to 2.8‐fold higher in stationary phase cells of all species except for L. tropica in which the activities of stationary and log phase cells were equal; L. mexicana amazonensis had the highest histone‐specific protein kinase activity and L. donovani the lowest. When viable, motile promastigotes of all five species were incubated for 10 min with [γ‐32P]ATP and Mg2+ (10 mM) in the absence of exogenous histone acceptor; about one dozen proteins were phosphorylated in each case. Both log phase and stationary phase promastigotes of all five species extensively phosphorylated a 50‐kDa protein that had the mobility of tubulin. Incubation of pure calf brain tubulin with [γ‐32P]ATP and purified L. donovani protein kinase resulted in extensive phosphorylation of the former. Highly infective metacyclic forms (PNA‐) of L. major, isolated from a stationary culture using the peanut agglutinin (PNA), contained eight times more histone‐specific protein kinase activity than noninfective log phase cells (PNA+). The PNA‐ and PNA+ forms of L. major both phosphorylated a 50‐kDa protein when incubated with [γ‐32P]ATP and magnesium or manganese ions (10 mM); the 50‐kDa protein was precipitated by anti‐tubulin rabbit antibodies. Extracts of all five species contained large amounts of acid phosphatase activity. With the exception of L. braziliensis panamensis for which late log phase organisms contained 12‐fold more tartrate‐resistant acid phosphatase activity than did early log phase cells, stationary and log phase parasites contained approximately the same amount of acid phosphatase activity.
Duboscquella cachoni N. Sp., a Parasitic Dinoflagellate Lethal to Its Tintinnine Host Eutintinnus pectinis1
Authors: COATS D. WAYNE
Published: May 2007

The parasitic dinoflagellate Duboscquella cachoni n. sp. is described from infestations of the tintinnine ciliate Eutintinnus pectinis collected from the Chesapeake Bay, a major North American estuary located on the east coast of the United States. Examination of parasite life history, morphology, and developmental processes reveals that D. cachoni differs from other members of the genus by the structure of the trophont, the pattern of sporogenesis, and spore morphology. Sporogenesis results in the production of either biflagellated macrospores, microspores with a single flagellum, or a cyst‐like stage. The number of spores formed per infestation and their survival outside the host vary with spore type. Infested ciliates are apparently unable to reproduce, and infestations are always fatal to E. pectinis. Aspects of parasite biology and observations of a natural host‐parasite assemblage suggest that D. cachoni may have a significant impact on its host's population dynamics.
Ultrastructure and Ecology of Calycomonas ovalis Wulff, 1919, (Chrysophyceae) and Its Redescription as a Testate Rhizopod, Paulinella ovalis N. Comb. (Filosea: Euglyphina)1
Authors: JOHNSON PAUL W. , HARGRAVES PAUL E. , SIEBURTH JOHN McN.
Published: May 2007

An exceptional bloom (109 cells/liter) of a unicellular alga, Aureococcus anophagefferens, in Narragansett Bay, RI, was accompanied by unusually high numbers (6 times 106 tests/liter) of vase‐shaped cells of Calycomonas ovalis Wulff, hitherto considered a flagellated chrysophyte. Phase contrast light microscopy showed the characteristic oval lorica or test of C. ovalis, ca. 3.0 times 4.5 μm. Transmission electron microscopy of thin sections of natural populations revealed, however, that C. ovalis is actually a rhizopod within a test of electron‐dense scales. This estuarine, planktonk testacean extends a pseudopodium through a narrow pseudostome and lacks chloroplasts or flagella. It is a bacterivore and feeds primarily on unicellular cyanobacteria. The morphology, ultrastructure, and cell division of C. ovalis are described. These characteristics place C. ovalis with the genus Paulinella (Sarcodina: Filosea: Euglyphina), which at present contains the single species, P. chromatophora Lauterbom. Calycomonas ovalis is thus assigned to Paulinella as P. ovalis n. comb.
Taxonomic Descriptions of One New Species and Redescription of Four Species in the Family Strombidiidae (Ciliophora, Oligotrichida)1
Authors: MONTAGNES D. J. S. , LYNN D. H. , STOECKER D. K. , SMALL E. B.
Published: May 2007

ABSTRACT Five ciliate species collected from the Woods Hole area were examined by protargol silver impregnation and scanning electron microscopy. These ciliates have been shown to sequester and use chloroplasts obtained from flagellate prey. One new species, Strombidium chlorophilum, is described. Four other species, Strombidium capitatum (Leegaard, 1915) Kahl, 1932, Strombidium conicum (Lohmann, 1908) Wulff, 1919, Strombidium acutum (Leegaard, 1915) Kahl, 1932, and Laboea strobila Lohmann, 1908, are redescribed. Characters used in describing the Strombidiidae include cell size and shape, anterior and ventral polykinetids, macronuclear shape and size, the kinetid “girdle,” the ventral kinety, the trichites, and the paroral kinety. The rationale for using these characters as taxonomic criteria is discussed.
Restriction Endonuclease Analysis of Mitochondrial DNA as an Aid in the Taxonomy of Naegleria and Vahlkampfia1
Authors: MILLIGAN STEPHEN M. , BAND R. NEAL
Published: May 2007

ABSTRACT Using restriction enzyme analysis, mitochondrial DNA fragment patterns from seven strains of pathogenic and nonpathogenic Naegleria and one strain of Vahlkampfia were compared to estimate nucleotide sequence divergence. Significantly high levels of estimated genetic variation between strains of N. gruberi, N. fowleri, and N. jadini support the current taxonomic level of the individual Naegleria species and suggest a distinct phylogeny for each group. Naegleria lovaniensis, strain TS, was shown to have significant nucleotide sequence homology with N. gruberi, strain EGs, suggesting that the two groups share a close taxonomic relationship. The pathogenic strain MB‐41 of N. fowleri exhibited distinct genetic divergence from the highly homologous, pathogenic strain Nf66 and the drug‐cured strain 6088. Morphologically distinct strains EGs and 1518/la of N. gruberi exhibited significantly large sequence divergence consistent with a more distant taxonomic relationship. Amoebae from the genus Vahlkampfia expressed genetic similarity with strains of N. gruberi.
Goussia girellae N. Sp. (Apicomplexa: Eimeriorina) in the Opaleye, Girella nigricans1
Authors: KENT MICHAEL L. , FOURNIE JOHN W. , SNODGRASS ROBERT E. , ELSTON RALPH A.
Published: May 2007

ABSTRACT Goussia girellae n. sp. is described from the opaleye fish, Girella nigricans. Merogonic stages were observed in the apices of intestinal epithelial cells, in the lamina propria, and in extra‐intestinal sites including liver, gills, and spleen. Gamonts were observed in the intestinal epithelial cells. Only unsporulated oocysts were detected in the intestine, and sporulation occurred when feces containing oocysts were incubated for 48 h in seawater at 21°C. Oocysts are elongated (24.8 × 14.7 μm) with a wall about 200 nm thick and have no residuum, micropyle, or polar granule. Sporocysts are ellipsoid (8.5 × 4.5 μm), have a thin two‐layered wall approximately 30 nm thick, and consist of two valves joined by a suture. Although moribund opaleye were also infected with Gyrodactylus sp., Cryptobia sp., Cardicola sp., and epitheliocystis organisms (chlamydia), all fish were heavily infected with G. girellae and morbidity was thus attributed to the coccidium.
Fine Structure and Taxonomic Position of the Giant Amoeboid Flagellate Pelomyxa palustris1,2
Authors: GRIFFIN JOE L.
Published: May 2007

ABSTRACT Specimens of Pelomyxa palustris from five collecting sites had numerous nonmotile flagella. The structures are called flagella because of morphological similarities to flagella and because P. palustris has affinities with amoeboid flagellates. Flagella were photographed on living cells and studied by transmission and scanning electron microscopy. From 64 to 742 flagella per cell were estimated from scanning electron microscopy of ten cells 204 to 1269 μm in length. The nonmotile flagella arise from basal granules which were, in one strain, surrounded by radiating electron‐dense microtubules. This strain also had excess axonemal microtubules. Abundant cytoplasmic microtubules were arranged in several different patterns. In about half of the P. palustris cells in which nuclei were studied, microtubules were either apposed to the nuclear membrane in a parallel alignment (with some also radiating) or radiating from the nuclear membrane (with none parallel). Bacteria associated with nuclei were of three characteristic types: Gram‐negative rods, Gram‐positive rods, and large rods. All nuclei within a given trophozoite had similar perinuclear features. Recent proposals for separation of Pelomyxa to its own phylum (based on its proposed primitive, unique nature) can not be justified. Pelomyxa is a complex, highly specialized organism adapted to live in a specific fresh‐water environment. Mastigamoebid amoeboid flagellates of the genera Mastigamoeba, Mastigella, Mastigina, and possibly Dinamoeba are placed with Pelomyxa within the order Pelobiontida Page, 1976, emend., containing two families. Pelomyxidae Schulze, 1877, and Mastigamoebidae Goldschmidt, 1907.
Stage Depandent Inhibition of Plasmodiun falcipaium falciparum by Potent Ca2+ and Calmodulin Modulators
Authors: TANABE KAZUYUKI , IZUMO ADIHISA , KATO MAYUMI , MIKI ATSUSHI , DOI SYUICHI
Published: May 2007

The effects Ca2+ channel blockers, verapamil, nicardipine and diltiazem, and of potent calmodulin (CaM) inhibitors, trifluoperazine (TFP), calmidazolium, W‐7 and W‐5, on Plasmodium falciparum in culture were examined. Among Ca2+ blockers, nicardipine was the most potent with the 50% inhibitory concentration (IC50) of 4.3 μM at 72 h after culture. Parasites were more sensitive to calmidazolium and W‐7 with IC50 of 3.4 and 4.5 μM, respectively, than to TFP and W‐5. All Ca2+ blockers and CaM inhibitors suppressed parasite development at later stages. Nicardipine, ditiazem, calmidazolium and W‐5 also retarded parasite development at earlier stages and/or subsequent growth following pretreatment. Verapamil, nicardipine, TFP and calmidazolium reduced erythocyte invasion by merozoites. Fluroscence microscopy with the cationic flurescent dye rhodamine 123 revealed that nicardipine. TFP and calmidazolium depolarized both the plasma membrane and mitochondrial membrane potentials of the parasite. It is therefore considered that although al Ca2+ and CaM antagonists tested here influence parasite development at later stages, they are multifunctional, having effects not directly associated with Ca2+ channels or CaM.
The Inositol Lipids of Paramecium tetraurelia and Preliminary Characterizations of Phosphoinositide Kinase Activity in the Ciliary Membrane
Authors: SUCHARD SUZANNE J. , RHOADS DENNIS E. , KANESHIRO EDNA S.
Published: May 2007

Inositol glycerolipids make up less than 10% of total phospholipids of Paramecium tetraurelia cells. Unlike inositol lipids found in mammalian and other cell types, these lipids from Paramecium lack arachidonic acid. It was demonstrated that kinase and possibly phosphatase enzymes that interconvert phosphatidylinositol (PI), phosphatidylinositol phosphate (PI‐P) and phosphati‐dylinositol‐bis‐phosphate (PI‐P2) exist in ciliary membranes of this ciliate. When exogenous soybean PI and [γ‐32P]ATP were provided as substrates, isolated cilia preparations exhibited PI and PI‐P kinase activities as demonstrated by the incorporation of radiolabel into PI‐P and PI‐P2. Kinase activity was activated by millimolar [Mg2+] and inhibited by millimolar [Ca2+]. Significant inhibition of kinase activity in the presence of unlabeled excess ATP suggested that ATP is the preferred phosphate donor for this reaction. Of 4 suborganellar fractions of isolated cilia, the membrane fraction had the greatest kinase activity indicating that the enzyme(s) is membrane‐associated
Nucleic Acids of Entamoeba histolytica
Authors: ALBACH RICHARD A.
Published: May 2007

This review will concentrate on certain aspects of the nucleic acids of Entamoeba histolytica. Utilization and synthesis of purines and pyrimidines will initially be briefly discussed, e.g. salvage vs. de novo pathways, uptake studies and recognition of at least 4 transport loci. Data will be presented which show that the distribution and synthesis of RNA (to a lesser extent DNA) in the nucleus is basically the opposite one finds in other eukaryotes, viz. most RNA (ribosomal?) is synthesized (or accumulates) in the peripheral chromatin (functional equivalent of nucleolus?). The DNA is distributed and synthesized primarily throughout the nucleus. It is usually so dispersed that it will not stain with e.g. the standard Feulgen technique, unless the DNA condenses around the endosome (not a nucleolar equivalent) prior to nuclear division. Isolation of rRNA was difficult due, in part, to potent and difficult to inhibit RNase(s), some of which are apparently intimately bound to ribosomal subunits. The 25S (1.3 kDa), 178 (0.8 kDa) and 58 rRNA were recovered after isolation with a high salt SDS‐DEP technique. This is the only procedure which enables us to obtain high yields of 258 rRNA: guanidine or guanidinium which permits isolation of intact functional mRNA results in isolation of small amounts of 28 RNA relative to 178 RNA. The 258 RNA is “nicked” (apparently during nuclear processing) and dissociates readily into 1 78 (0.7 kDa) and 168 (0.6 kDa) species, and a more rigidly bound 5.88 species. A small amount of “unnicked” 258 RNA was recovered with guanidine. Two DNA‐dcpendent RNA polymerases (I and II) with a pronounced preference for denatured DNA as template were eluted from DEAE‐Sephadex in reverse order of what occurs in other eukaryotes, except Physarum polycephalum. This conclusion was based on salt optima and alpha‐amanitin sensitivity studies. Initial characterization of DNA isolated with a procedure capable of isolating > 100‐kbp Leishmania DNA showed that undigested DNA migrates as a broad band between markers 6 and 24 kbp. The persistent recovery of such a “band” by us and Perez‐Mutul et al. no larger than ca. 24 kbp (with the exception of >48 kbp DNA isolated by Hernandez et al. using an in situ lysis technique which did not include a proteinase) may be due to nicks introduced during isolation; or, perhaps much of the amebal DNA exists in vivo as gene sized fragments. However, preliminary data generated using orthogonal pulse‐field agarose gel electrophoresis do suggest that amebal DNA may be in small chromosomes.
Hydrogen Production by Rumen Holotrich Protozoa: Effects of Oxygen and Implications for Metabolic Control by In Situ Conditions
Authors: HILLMAN D. LLOYD. K. , YARLETT N. , WILLIAMS A. G.
Published: May 2007

Experiments with washed suspensions of holotrich protozoa (Isotricha spp. and Dasytricha ruminantium) showed that both organisms have an efficient 0,‐scavenging capability (apparent Km values 2.3 and 0.3 μM, respectively). Reversible inhibition of H2, production increased almost linearly with increasing O2 up to 1.5 μM; higher levels of O2 gave irreversible inhibition. In situ determinations of H, CH4, O2, and CO2, in ovine rumen liquor, using a membrane inlet mass spectrometer probe, indicated that O2, was present before feeding at 1‐1.5 μM and decreased to undetectable levels (<0.25 μM) within 25 min after feeding. A transient increase in O2. concentration after feeding occurred only in defaunated animals and resulted in suppression of CH4 and CO2 production. The presence of washed holotrich protozoa decreases the O2 sensitivity of CH4 production by suspensions of a cultured methanogenic bacterium Methanosarcina barkeri. It is concluded that holotrich protozoa play a role in ruminal O2 utilization as well as in the production of fermentation end products (especially short‐chain volatile fatty acids) utilized by the ruminant and H, utilized by methanogenic bacteria. These hydrogenosome‐containing protozoa thus both control patterns of fermentation by influencing O2 levels, and are themselves regulated by the low ambient O2 concentrations they experience in the rumen.
Action of the Major Protease from Entamoeba histolytica on Proteins of the Extracellular Matrix
Authors: SCHULTE WERNER , SCHOLZE HENNING
Published: May 2007

The action of the major protease from the parasitic protozoon Entamoeba histolytica, a cysteine protease of M, 27,000–29,000, on some important proteins of the extracellular matrix has been studied. The isolated protease degraded the extracellular matrix proteins from human tissue collagen type IV and V as well as laminin and fibronectin with different velocities and specificities under native conditions. Whereas the degradation of fibronectin and laminin proceeded rapidly, yielding distinct fragment patterns, the breakdown of the collagen types happened more slowly and incompletely. The digestion of the denatured isolated α2‐chain of bovine collagen type I was very fast and unspecific requiring only 1/10 of the enzyme activities as compared with the other substrates mentioned above. Nearly 85% of the overall proteolytic activity of a soluble fraction of E. histolytica was strongly inhibited by antibodies against the purified histolytic protease as well as by cystatin from chicken egg white, a specific protein inhibitor of cysteine proteases. We conclude that the histolytic protease represents by far the highest portion of soluble proteolytic activity in E. histolytica which is sufficient to destroy the extracellular matrix of the host.
Breakdown of Glucopolysaccharides in Entamoeba histolytica by Phosphorylase
Authors: WERRIES ECKHARD , THURN INA
Published: May 2007

Homogenates of trophozoites of Entamoeba histolytica released glucose 1‐phosphate from amylopectin, glycogen, and amylose in a ratio of 100:78:74 at glucopolysaccharide concentrations of 0.1%. By use of self‐generating Percoll gradients this activity was shown to be particulate and associated with glycogen. The phosphorylase was extracted from the 40,000 g pellet in aqueous medium and purified to homogeneity by gel filtration on Fractogel TSK HW‐55(F) followed by chromatography on Blue Sepharose CL‐6B. The purified enzyme was active not only against the glucopolysaccharides but also on dextrins with more than 3 glucose moieties, which were primarily formed by the action of amoebic amylases. At substrate concentrations of 1 mM nonreducing ends of each glucan, the phosphorolysis rate of the branched polysaccharides was about 1.75 × 104 times higher than those of the maltodextrins. By means of HPLC the sequential degradation of 4‐nitrophenyl‐maltoheptaoside (G7‐pNP) was studied. Native phosphorylase exhibited a relative molecular mass of Mr= 200,000 by gel filtration and gel electrophoresis. The SDS electrophoresis, under reducing conditions, indicated that the native enzyme was a dimer. Optimal degradation of the polysaccharides and dextrins was achieved at pH values of 7.5 and 7.0, respectively.
Isospora viridanae N. Sp., an Intranuclear Coccidian Parasite from the Canarian Skink, Chalcides viridanus (Lacertilia: Scincidae)
Authors: MATUSCHKA FRANZ‐RAINER
Published: May 2007

A caryotropic species of coccidium, Isospora viridanae n. sp. (Apicomplexa: Eimeriidae). has been found as a parasite in the Canarian skink, Chalcides viridanus Gravenhorst, 1851, from Tenerife, Spain, and is described here as a new species. Fully sporulaled oocysts of Isospora viridanae are spherical and measure 21.6 (1 7.6–23.4) nm in diameter. Mtcropyle, oocyst residuum and polar granule are ali absent. Oocysts of this coccidian, with a smooth bilayered wall, contain 2 ovoid sporocysts 13.2 (11.7–14.0) by 9.5 8.2–10 5) μm. A sporocyst residuum is present as well as a Stieda body and a substieda body. Most oocysts are found to be at the beginning of sporulanon when excreted and show 2 spherical sporoblasts. Sporulation is completed within 24 to 48 h at 23 × 2°C Sporozoites are 13–14 μm long and are about 2.5–3 μm wide. Endogenous stages of schizogony and gamogony develop in the nuclei of epithelial cells from the small intestine of the skink. Comparisons with other species of the genus found in lacertilian hosts indicate that it is a new species.
The Effect of Interleukin‐2 on Parasitemia and Myocarditis in Experimental Chagas' Disease
Authors: HULSEBOS LARRY H. , CHOROMANSKI LESZEK , KUHN RAYMOND E.
Published: May 2007

Previous investigations showed that interleukin‐2 (IL‐2) administered in vivo into mice infected with Trypanosoma cruzi reduced levels of parasitemia and increased longevity. Present experiments examined the effect of administration of different doses of IL‐2 at different times during infection in mice on parasitemia and histopathoiogy of heart tissue. Two different doses of IL‐2 (1,500 or 10,000 U) given at 3 different times during infection were equivalent in reducing parasitemia. All of the IL‐2 treated groups of mice had significantly lower numbers of circulating trypomastigotes as compared with controls not receiving this fymphokine. This IL‐2 treatment of T. crazi‐infected mice resulted also in lower numbers of pseudocysts in all 4 ventricular regions in the hearts. This was particularly evident in the more severely infected right ventricular wall; however, a similar decrease was not as apparent in the less severely infected left ventricular wall. The IL‐2 treated, infected mice showed minimal or no effect in reducing inflammation of myocardial cells. However, the mildest inflammation of ventricular wall tended to occur in mice receiving IL‐2 treatment either as a low dose (1,500 U) or a high dose (10,000 U) at 5, 7 and 9 days after infection as compared with mice treated later on. It was concluded that IL‐2 treatment of infected mice produced a significant decrease in parasitemia and decreased infection of myocardial cells. Key words. Heart, histopathoiogy, inflammation, lymphokine, myocardial cells, pseudocyst, Trypanosoma cruzi.
Modulation of the Host's Immune Response to Plasmodium berghei by a Parasite‐Derived Immunosuppressive Factor
Authors: SROUR EDWARD F. , SEGRE MARIANGELA , SEGRE DIEGO
Published: May 2007

ABSTRACT. It is well known that Plasmodium‐infected hosts are immunosuppressed, as shown by their depressed immune responsiveness to a variety of antigens. It is not known, however, whether the immune response of malaria‐infected animals to the malarial parasite itself is suppressed. The availability of a noninfectious, immunosuppressive factor (ISF) derived from Plasmodium berghei‐infected rat erythrocytes made it possible to investigate this question. Mice infected with P. berghei and injected with the ISF had higher levels of parasitemia and shorter survival times than control mice that were similarly infected but were treated with control material derived from noninfected rat erythrocytes or with saline solution. Conversely, mice immunized against the ISF and then infected with P. berghei had lower parasitemias and longer survival times than mice immunized with the control material or with saline solution. We conclude that immunosuppression in murine malaria affects the course of malaria infection.