bluuebunny/crossref_metadata_2025 huggingface dataset:
Antisporozoite Antibodies with Protective and Nonprotective Activities: In Vitro and In Vivo Correlations Using Plasmodium gallinaceum, an Avian Model
Authors: RAMIREZ ADELINA D. , ROCHA ELIANA M. M. , KRETTLI ANTONIANA U.
Published: May 2007

ABSTRACT. A correlation was observed between in vivo and in vitro activity of six monoclonal antibodies (mAb) against the major circumsporozoite protein of the avian malaria Plasmodium gallinaceum as follows. (1) Two mAb were protective, totally abrogating sporozoite infectivity to chicks, its natural host, in vivo; they caused 100% inhibition of sporozoite invasion (ISI) in vitro to SL‐29 chicken fibroblasts and intense ISI to cultured chicken macrophages, as well as inhibited the exoerythrocytic development of sporozoites taken up by macrophages, the initial cell host of P. gallinaceum sporozoites. (2) Two mAb were partially protective in that they reduced sporozoite infectivity to chicks, caused partial ISI to SL‐29 and macrophage cells and partial inhibition to the exoerythrocytic development of sporozoites in macrophages in vitro. (3) Two mAb were totally inactive in vivo although they both bound to the sporozoite antigens as detected by indirect immunofluorescence, western blot, and ELISA; they both failed to induce ISI or inhibit the exoerythrocytic development in macrophages. The possible participation of macrophages as the initial cell type involved in sporozoite destruction in the presence of anti‐circumsporozoite antibodies is discussed.
The Order Euplotida (Ciliophora): Taxonomy, with Division of Euplotes into Several Genera
Authors: BORROR ARTHUR C. , HILL BRUCE F.
Published: May 2007

ABSTRACT. The order Euplotida represents a monophyletic order of five families of hypotrich ciliates united by morphology, stomatogenesis, ultrastructure, cyst structure, and behavior. A review of variability of ciliation and nuclei among the 14 genera suggests that lines of evolution may have involved both the loss of cirri and nuclear simplification. We present a binary key to genera in the families Aspidiscidae (Aspidisca and Euplotaspis), Certesiidae n. fam. (Certesia), Gastrocirrhidae (Cytharoides, Euplotidium, and Gas‐trocirrhus), Uronychiidae (Diophryopsis, Diophrys, Paradiophrys, and Uronychia), and Euplotidae. The latter family contains species formerly in the genus Euplotes. Based primarily on cortical structure, endosymbionts, data from morphometric analysis, and ecology, we recognize four different groups. The first group of species remains in Euplotes with Euplotes charon as type. We place a second group of species into the genus Moneuplotes Jankowski 1979 with Moneuplotes vannus (Müller, 1786) as type. We erect two new genera: Euplotoides n. g. and Euplotopsis n. g. with Euplotoides patella (Müller, 1773) n. comb. and Euplotopsis affinis (Dujardin, 1841) n. comb. as type species respectively. We discuss possible phylogenetic relationships within the order.
Identification and Partial Purification of a Stage‐Specific 33 kDa Mitochondrial Protein as the Alternative Oxidase of the Trypanosoma brucei brucei Bloodstream Trypomastigotes
Authors: CHAUDHURI MINU , AJAYI WILFRED , TEMPLE STARLETT , HILL GEORGE C.
Published: May 2007

ABSTRACT. The glycerophosphate oxidase (GPO), the unique terminal oxidase of bloodstream trypanosome (TAO), appears to be functionally similar to the alternative oxidases of some plants and higher fungi. Immunoblotting of mitochondrial proteins of bloodstream trypomastigotes of Trypanosoma brucei brucei with monoclonal or polyclonal antibodies to Sauromatum guttatum (voodoo lily) and Symplocarpus foetidus (skunk cabbage) alternative oxidases respectively revealed two proteins of about 33 kDa (p33) and 68 kDa (p68). These proteins are not present in procyclic trypomastigotes. Electrophoresis under rigorous denaturing conditions indicated p68 to be the dimer of p33. Indirect immunofluorescent studies of bloodstream and procyclic trypomastigotes with monoclonal antibody to plant alternative oxidase also showed the localization of 33 kDa protein in the mitochondria of the bloodstream trypomastigotes. The functional TAO activity could be solubilized efficiently from the mitochondrial membrane of the bloodstream trypomastigotes by 1% NP‐40 or 10 mM lauryl maltoside. When fractionated by Superose 12 gel filtration chromatography, p33 was co‐purified with the TAO enzymatic activity. The apparent molecular size of the active enzyme complex was found to be 160 kDa. Gradual disappearance of the 33 kDa protein and the TAO enzymatic activity were well correlated during in vitro differentiation of the bloodstream to procyclic trypomastigotes. This study implies that the net biosynthesis of p33, an essential subunit of TAO, is decreased during differentiation from bloodstream to procyclic trypomastigotes.
Production of Serine Proteases by the Oyster Pathogen Perkinsus marinus (Apicomplexa) In Vitro
Authors: PEYRE JEROME F. LA , SCHAFHAUSER DORIS Y. , RIZKALLA ESAM H. , FAISAL MOHAMED
Published: May 2007

ABSTRACT. Analysis of the cell‐free supernatants of Perkinsus marinus cultures by sodium dodecylsulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) and silver staining revealed the presence of as many as 17 bands ranging in molecular weight from 239 to 32 kDa. These bands were not present in un‐inoculated medium. Moreover, P. marinus produces extracellular proteins that possess proteolytic activities; the cell‐free supernatants of P. marinus cultures could digest a variety of proteins including gelatin, casein, fibronectin and laminin. Oyster plasma was also digested by cell‐free culture supernatants. The proteolytic activity in cell‐free culture supernatants was detected 24 h post‐inoculation, while no proteolytic activity could be detected in cell lysates. The proteolytic activities were characterized using substrate‐impregnated sodium dodecylsulfate‐polyacrylamide gels and had approximate molecular weights ranging from 55 to 35 kDa. The proteolytic activity of cell‐free culture supernatants was inhibited by the serine protease inhibitors phenylmethylsulphonyl fluoride, 3,4‐dichloroisocoumarin and soybean trypsin inhibitor. In contrast, inhibitors (i.e. trans‐epoxysuccinyll‐leucylamido(4‐guanidino)‐butane, 1, 10‐phenanthroline, captopril, ethylenediaminetetracetic acid, pepstatin A or diazoacetyl‐DL‐norleucine methyl ester) from the other three classes of proteases had no effect. It was concluded that the P. marinus proteases in cell‐free culture supernatants are serine proteases.
Membrane Skeletal Proteins and Their Integral Membrane Protein Anchors are Targets for Tyrosine and Threonine Kinases in Euglena
Authors: FAZIO MARC J. , SILVA ALBA C. DA , ROSIERE THOM K. , BOUCK G. BENJAMIN
Published: May 2007

ABSTRACT. Proteins of the membrane skeleton of Euglena gracilis were extensively phosphorylated in vivo and in vitro after incubation with [32P]‐orthophosphate or γ‐[32P] ATP. Endogenous protein threonine/serine activity phosphorylated the major membrane skeletal proteins (articulins) and the putative integral membrane protein (IP39) anchor for articulins. The latter was also the major target for endogenous protein tyrosine kinase activity. A cytoplasmic domain of IP39 was specifically phosphorylated, and removal of this domain with papain eliminated the radiolabeled phosphoamino acids and eliminated or radically shifted the PI of the multiple isoforms of IP39. In gel kinase assays IP39 autophosphorylated and a 25 kDa protein which does not autophosphorylate was identified as a threonine/serine (casein) kinase. Plasma membranes from the membrane skeletal protein complex contained threonine/serine (casein) kinase activity, and cross‐linking experiments suggested that IP39 was the likely source for this membrane activity. pH optima, cation requirements and heparin sensitivity of the detergent solubilized membrane activity were determined. Together these results suggest that protein kinases may be important modulators of protein assembly and function of the membrane skeleton of these protistan cells.
Entamoeba histolytica Encodes a Highly Divergent β‐Tubulin
Authors: KATIYAR SANTOSH K. , EDLIND THOMAS D.
Published: May 2007

ABSTRACT. The microtubules of the amitochondrial parasite Entamoeba histolytica are atypical in certain respects. Consistent with this, we report that E. histolytica encodes the most divergent β‐tubulin identified to date, with only 54% to 58% identity to β‐tubulins from various species. A similarly divergent β‐tubulin is encoded by the related Entamoeba invadens; single gene copies appear to be present in both organisms. The Entamoeba sequences were compared with a database of 101 β‐tubulins, including the highly divergent sequence from another amitochondrial protozoan, Trichomonas vaginalis. A total of 81 residues were universally conserved, and 76 residues varied only once. Correlations with previous studies indicate that microtubule function is altered when most, but not all, conserved residues are mutated.
The Physiological Ecology of Planktonic Sarcodines with Applications to Paleoecology: Patterns in Space and Time1
Authors: ANDERSON O. ROGER
Published: May 2007

ABSTRACT. Planktonic sarcodines, suspended in the water column, are conveniently grouped into three categories based on functional morphology: (1) gymnamoebae and their relatives, which lack major living or nonliving compartmentalizing barriers, (2) foraminifera, and testate amoebae enclosed by a test or shell with one or more major openings, but lacking extensive cytoplasmic compartmentalizing barriers, and (3) radiolaria, which exhibit distinct compartmentalization of the cytoplasm into functional zones. Differences in feeding strategies and trophic activity of members in the three groups reflect in part these differences in functional morphology. Members of all three groups form symbiotic associations with Monera and protists, including algae, thus partially offsetting interspecific trophic competition among species occupying the same water mass. Physiological and morphological adaptations supporting a symbiotic association are presented. C14‐labeling studies of endosymbiotic radiolarian species show a substantial contribution of carbon to the host. Rates of calcification (planktonic foraminfera) and silica deposition (radiolaria) are reported, based on morphometric analyses and isotopic labeling studies. Major distributional patterns in space and time for each of the three groups, and some ecological principles explaining these regularities, are presented as related to population growth dynamics, niche differentiation, water‐mass properties, and the role of symbionts in supporting highly diverse communities of species within the same locale in the water column.
DNA Polymorphism Revealed by Arbitrary Primers Polymerase Chain Reaction Among Blastocystis Strains Isolated from Humans, a Chicken, and a Reptile
Authors: YOSHIKAWA HISAO , NAGONO ISAO , YAP EU HIAN , SINGH MULKIT , TAKAHASHI YUZO
Published: May 2007

DNA polymorphisms of different strains of Blastocystis isolated from humans, a chicken, and a reptile were examined by an arbitrary primer PCR method. Two strains of Blastocystis hominis isolated from humans in the USA and Japan yielded nearly identical PCR products. However, one strain of B. hominis (isolated from a human in Singapore) yielded quite different PCR products. Blastocystis sp. isolated from a chicken yielded PCR products similar to those of the former two strains, while Blastocystis lapemi, isolated from a reptile, shared no bands with any of the other isolates. These results indicate the possibility that our isolate from the chicken is a zoonotic strain, and that there is intraspecific variation of Blastocystis hominis.
Internal Eliminated Segments (IESs) of Oxytrichidae1
Authors: PRESCOTT DAVID M. , DuBOIS MICHELLE L.
Published: May 2007

ABSTRACT Internal eliminated segments (IESs) are sequences that interrupt coding and noncoding regions of germline (micronuclear) genes of ciliated protozoa. IESs are flanked by short, unique repeat sequences, which are presumably required for precise IES excision during macronuclear development. Coding and noncoding segments of genes separated by IESs are called macronuclear‐destined segments, or MDSs. We have compiled the characteristics of 89 individual IESs in 12 micronuclear genes in the Oxytricha and Stylonychia genera to define the IES phenomenon precisely, a first step in determining the origin, function and significance of IESs. Although all 89 IESs among the 12 different genes are AT‐rich, they show no other similarity in sequence, length, position or number. Two main types of IESs are present. IESs that separate scrambled MDSs are significantly shorter and more frequent and have longer flanking repeat sequences than IESs that intervene between nonscrambled MDSs. A comparison of the nonscrambled gene encoding β‐telomere binding protein in three species of hypotrichs shows that even in the same gene IESs are not conserved in sequence, length, position, or number from species to species. A comparison of IESs in the scrambled gene encoding actin I in the three species shows that the evolutionary behavior of IESs in a scrambled gene may be more constrained. However, IESs in the scrambled actin I gene have shifted along the DNA molecule during evolution. In total, the various studies show that IESs are hypermutable in sequence and length. They insert, excise, and shift along DNA molecules more or less randomly during evolution, with no discernible function or consequences.
Developmentally Controlled Rearrangement of Surface Protein Genes in Paramecium tetraurelia1
Authors: FORNEY JAMES D. , YANTIRI FERDA , MIKAMI KAZUYUKI
Published: May 2007

ABSTRACT Early research on Paramecium genetics highlighted the role of the cytoplasm on inheritance. Today this tradition continues as recent investigations of macronuclear development in Paramecium have revealed unusual cytoplasmic effects that are not easily explained within current paradigms. It is generally assumed that most programmed DNA rearrangements in ciliates are regulated by cis acting signals encoded within the germline (micronuclear) DNA, but there are increasing examples in which the old macronucleus acts through the cytoplasm (in trans) to affect the loss and rearrangement of DNA in the developing macronucleus. The remarkable specificity of this effect has forced a reevaluation of the standard view of macronuclear determination in Paramecium. This review summarizes our knowledge of the effect of the old macronucleus on the developmentally controlled rearrangements of the P. tetraurelia, stock 51A and B variable surface protein genes.
Evidence for the Heterolobosea from Phylogenetic Analysis of Genes Encoding Glyceraldehyde‐3‐Phosphate Dehydrogenase
Authors: ROGER ANDREW J. , SMITH MICHAEL W. , DOOLITTLE RUSSELL F. , DOOLITTLE W. FORD
Published: May 2007

ABSTRACT The phylogenetic relationships between major slime mould groups and the identification of their unicellular relatives has been a subject of controversy for many years. Traditionally, it has been assumed that two slime mould groups, the acrasids and the dictyostelids were related by virtue of their cellular slime mould habit; a view still endorsed by at least one current classification scheme, However, a decade ago, on the basis of detailed ultrastructural resemblances, it was proposed that acrasids of the family Acrasidae were not relatives of other slime moulds but instead related to a group of mostly free‐living unicellular amoebae, the Schizopyrenida. The class Heterolobosea was created to contain these organisms and has since figured in many discussions of protist evolution. We sought to test the validity of Heterolobosea by characterizing homologs of the highly conserved glycolytic enzyme glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) from an acrasid, Acrasis rosea; a dictyostelid, Dictyostelium discoideum; and the schizopyrenid Naegleria andersoni. Phylogenetic analysis of these and other GAPDH sequences, using maximum parsimony, neighbour‐joining distance and maximum likelihood methods strongly supports the Heterolobosea hypothesis and discredits the concept of a cellular slime mould grouping. Moreover, all of our analyses place Dictyostelium discoideum as a relatively recently originating lineage, most closely related to the Metazoa, similar to other recently published phylogenies of protein‐coding genes. However, GAPDH phylogenies do not show robust branching orders for most of the relationships between major groups. We propose that several of the incongruencies observed between GAPDH and other molecular phylogenies are artifacts resulting from substitutional saturation of this enzyme.
Isospora atrata N. Sp. (Apicomplexa, Eimeriidae): a New Coccidium Isolated from Carduelis atrata (Passeriformes, Fringillidae)
Authors: ROSSI GIACOMO , PERRUCCI STEFANIA , MACCHIONI GUIDO
Published: May 2007

ABSTRACT Large numbers of coccidian oocysts belonging to the genus Isospora were obtained from the intestinal contents of 98 Carduelis atrata imported into Italy from South America during the months of August through December 1994. The oocysts are sub‐spherical and average 21 × 20.3 μm (19.4–23.5 μm × 18.5–22 μm), have a bilayered wall, and an oval polar granule (rarely two). The sporocysts are elliptical and measure 18.8 μm × 10.3 μm (17.5–18.94 μm × 9.5–11.0 μm). The Stieda body protrudes slightly from the end of the sporocyst. A large sporocyst residuum is present, consisting of many granules that may be in a compact mass or scattered. Since this Isospora sp.does not resemble any other species of Isospora previously described from birds of the genus Carduelis, it has been named Isospora atrata n. sp. after the host. Disseminated asexual stages were found in mononuclear cells derived from formalin‐fixed post mortem material, suggesting this coccidian may represent an Atoxoplasma‐like parasite. Four coccidia‐free Serinus canarius L. cohabitated for a long period (4 mo) with infected C. atrata but oocysts were never found in the stool of these birds.
Diagnosis of PCP by ITSs Nested PCR on Notinvasive Oropharingeal Samples
Authors: ATZORI CHIARA , AGOSTONI FIORENZA , GUBERTINI GUIDO , CARGNEL ANTONIETTA
Published: May 2007

Pneumocystis carinii pneumonia is an opportunistic disease usually affecting immunocompromised hosts. Diagnosis is based on the microscopical detection of microrganism on BAL, an invasive sample which requires pt compliance for collection and skilled health care personnel for examination. In order to verify the possible diagnostic utility of noninvasive specimens collected in the upper respiratory tract we examined by the Internal Transcribed Spacers (ITSs) nested PCR, 39 oropharingeal samples (garglings) collected from 20 HIVAb positive pts and from 15 healthy controls.
Sporogonic Development of the Gregarine Ascogregarina taiwanensis (Lien and Levine) (Apicomplexa: Lecudinidae) in Its Natural Host Aedes albopictus (Skuse) (Diptera: Culicidae)
Authors: CHEN WEI‐JUNE , WU SHU‐TSUAN , CHOW CHIA‐YI , YANG CHING‐HSIANG
Published: May 2007

ABSTRACT. Sexual reproduction of Ascogregarina taiwanensis occurred in pupal Malpighian tubules of its natural host Aedes albopictus, resulting in the formation of gametocysts within which oocysts developed. Sporogony proceeded in each newly formed unsporulated oocyst; eight sporozoites were formed after completion of nuclear divisions followed by the cytokinesis. Developing oocysts were separated by gradient centrifugation on percoll based on different buoyant densities. The slender sporozoite had a typical apical complex composed of a coiled conoid, polar rings, rhoptries with ductules, subpellicular microtubules and micronemes. An apical cavity was seen in the gland‐like rhoptries. Mitochondria of gregarines were not seen in any stage during the sporogony. Howeever, amylopectin granules were frequently seen in the cytoplasm. These starch‐related granules became scant when the sporozoite was formed. We assumed they were associated with the energy source. Since the apical complex was only present in the sporozoite stage, it was most likely related to the invasion of host epithelial cells of the midgut during the early phase of infection.
Redescription of Ellobiophrya brevipes (Laird, 1959) N. Comb. (Ciliophora, Peritrichia) and the Fine Structure of its Pellicle and Cinctum
Authors: CLAMP JOHN C. , BRADBURY PHYLLIS C.
Published: May 2007

ABSTRACT. A species of peritrich that attaches to gills of the skate, Raja erinacea, was identified by its original describer as a member of Caliperia, a genus characterized by having a noncontractile skeletal rod within the arms of its cinctum and by not having the cinctal arms bonded to one another at their tips. Our observations of the living ciliates confirmed by protargol impregnation and electron microscopy revealed that their cinctal arms are linked by a bouton and that the cytoskeletal structure within them has the fine structure of a myoneme. These characteristics place this peritrich unequivocally in the genus Ellobiophrya and it is thus renamed Ellobiophrya brevipes (Laird, 1959) n. comb. Clumps of epithelial cells clasped by the cincta of E. brevipes show damage at their bases but not on their luminal surfaces. The known species of Ellobiophrya are compared for significant structural differences that separate species of this genus.
Effects of Metazoan Predators on Ciliates in Freshwater Plankton Communities1
Authors: JACK JEFFREY D. , GILBERT JOHN J.
Published: May 2007

ABSTRACT. Ciliates are often important members of aquatic communities in terms of their biomass, productivity, trophic roles, or numerical abundance. The interaction of metazoan predators with ciliates will be mediated by a number of biotic factors, including the potential of ciliate populations for growth, the relative size of ciliates and metazooplankton, the species structure of the metazooplankton, and the defenses of ciliates. This paper reviews some of the recent laboratory an field data pertaining to these particular factor. Studies have generally shown that metazoans can reduce ciliate population growth rates, but this impact varies greatly with the ciliate and metazoans involved. Smaller ciliates are generally more vulnerable to metazoan predators than larger species, although this relationship will be affected by the defenses a ciliate may possess. The structure of the metazooplankton community itself will also affect ciliatemetazoan interactions. The suppression of ciliate populations by metazoans has important ecological consequences, and more study is needed to understand the interaction of these groups in aquatic systems.
Cellulase Activity of Leishmania major in the Sandfly Vector and in Culture
Authors: JACOBSON RAYMOND L. , SCHLEIN YOSEF
Published: May 2007

ABSTRACT. The secretion of cellulose‐degrading enzymes by Leishmania promastigotes in culture and in the sandfly vector was demonstrated. Two types of activity of cellulase enzyme‐complexes were measured: endoglucanases, which randomly cleave cellulose chains and cellobioydrolases, which remove cellobiose from the nonreducing end of the molecule. The assays demonstrated that enzymes with these activities were secreted into the culture medium by Leishmania major, L. donovani, and L. braziliensis. These activities were also found in cultures of Sauroleishmania agamae, Leptomonas seymouri, Herpetomonas muscarum, Crithidia fasciculata and Trypanosoma brucei brucei that had a relatively low endoglucanase activity. Both endoglucanase and cellobiohydrolase activities were found in the gut of L. major‐infected Phlebotomus papatasi, while gut preparations of uninfected sandflies had only cellobiohydrolase activity. The similar growth of L. major parasites in medium supplemented with either cellulose or glucose suggests these parasites can utilize cellulose.
Kinesis in Euplotes vannus‐Ethological and Electrophysiological Characteristics of Chemosensory Behavior
Authors: STOCK CHRISTIAN , KRÜPPEL THOMAS , LUEKEN WOLFGANG
Published: May 2007

ABSTRACT. Equally dispersed Euplotes vannus cells accumulate inside a drop of supernatant of a bacteria suspension that is surrounded by a reference solution. In the drop, frequencies of stops and backward jerks are tenfold increased. The sequences of directional changes and translocations prevent cells from leaving the chemostimulant region, as if they were trapped. This behavior is quickly induced after casual arrival in the drop and not by chemotactic influence over a larger distance. With intracellular recordings, we have found a K+ conductance decrease in chemically stimulated cells that prolongs the duration of spontaneously occurring depolarizations to 600‐1,700 ms by delaying repolarization. The freely fluctuating membrane potential shifts to more depolarized levels, although the total potential range is expanded in the positive and negative direction by 5.5 and 3.8 mV, respectively. Chemosensory behavior is explained and discussed with respect to these electrophysiological events.
Phylogenetic Position of Psalteriomonas lanterna Deduced from the SSU rDNA Sequence
Authors: WEEKERS PETER H. H. , KLEYN JANINE , VOGELS GODFRIED D.
Published: May 2007

ABSTRACT. The small subunit ribosomal DNA sequence (SSU rDNA) of the microaerophilic free‐living amoeboflagellate Psalteriomonas lanterna has been sequenced and analyzed. The gene is 1,945 bp long and has a G + C content of 33.4%. Based upon ultrastructural studies, P. lanterna has been placed in the class Lyromonadea within the phylum Percolozoa Cavalier‐Smith, 1991. However, based upon cytological characteristics, this microaerophilic free‐living amoeboflagellate appears to be very primitive. It shares certain characteristics in common with some archezoans, i.e. it lacks mitochondria and dictyosomes but contains hydrogenosomes. Despite sharing these characteristics with the amitochondriate taxa, P. lanterna is not related to any of these taxa but instead to the Vahlkampfiidae. Therefore, we used primary sequence data and the secondary structure of the SSU rDNA gene to determine the placement P. lanterna in the phylogenetic tree. Our analyses showed that P. lanterna groups as a sister taxon to the Vahlkampfiidae but probably diverged from them quite early.
Molecular Characterization of a Sarcoplasmic‐Endoplasmic Reticulum Ca+2 ATPase Gene from Trichomonas vaginalis
Authors: MEADE JOHN C. , LI CHUNLING , MOATE MICHELLE E. , DAVIS‐HAYMAN SARA R. , LUSHBAUGH WILLIAM B. , FINLEY RICHARD W.
Published: May 2007

ABSTRACT. DNA fragments homologous to P‐type cation translocating ATPase genes were identified in Trichomonas vaginalis by polymerase chain reaction (PCR) amplification. The genomic locus corresponding to one PCR fragment, TVCA1, contains a 3,055 base‐pair open reading frame encoding a 108,162 dalton protein composed of 981 amino acids. TVCA1 lacks introns, is present in a single copy, and is expressed as a 3.1 kb transcript with short 5’and 3’untranslated regions. Separate primer extension experiments map the 5’end of the TVCA1 transcript to 12 and 16 nucleotide bases (nt) upstream of the methionine initiation codon. The message polyadenylation site is located 62 nt downstream of the protein termination codon at a CA dinucleotide. The TVCA1 protein sequence shares 57‐58% similarity with rabbit, schistosome, trypanosome and malarial sarcoplasmic‐endoplasmic reticulum calcium (SERCA) pumps, and significantly lower similarity with plasma membrane calcium pumps and cation translocating ATPases of other ion specificities. Structural and functional domains identified in P‐type ATPases as well as 61/68 residues specifically implicated in SERCA pump activity are conserved in TVCA1. However, TVCA1 lacks binding sites for phospholamban regulation, thapsigargin inhibition and the calmodulin dependent protein kinase site phosphorylation present in other SERCA pumps.
Algorithmic Analysis of in Vitro Chemotherapy Against Pneumocystis carinii
Authors: ATZORI CHIARA , AGOSTONI FIORENZA , ANGELI ELENA , CARGNEL ANTONIETTA , DRAGO LORENZO , GISMONDO MARIA R.
Published: May 2007

The development of in vitro experimental chemotherapy against P.carinii has been hindered by the lack of efficient methods for continous cultivation of the microorganism. Various short‐term systems, allowing the production of infectious forms of Pneumocystis, can be employed for in vitro experimental chemotherapy [1,2,3]. The purpose of the present study is to describe a statistically relevant algorithmic model for the evaluation of P.carinii in short‐term in vitro culture and drug screening.
In Vitro Cultivation of Cryptosporidium parvum in the Non‐Adherent Human Monocytic THP‐1 Cell Line
Authors: LAWTON PHILIPPE , NACIRI MURIEL , MANCASSOLA ROSELYNE , PETAVY ANNE‐FRANCOISE
Published: May 2007

This study shows that the human monocytic cell line THP‐1 supports the growth of C. parvum.. Immunofluorescence controls showed that only source oocytsts remained after infection and disappeared within the first 24 h of culture. A continuous asexual life cycle proceeded throughout the experiments, with at least 15‐d cultures. This model provides a useful tool for studies on the biologyof C. parvum in cells involved in its transport in immunocompromised host.
Sphaerospora ovophila N. Sp. and Myxobolus algonquinensis N. Sp. (Myxozoa, Myxosporea), Ovarian Parasites of Fish from Algonquin Park, Ontario, Canada
Authors: XIAO CHONGXIE , DESSER SHERWIN S.
Published: May 2007

ABSTRACT. Sphaerospora ovophila n. sp. and Myxobolus algonquinensis n. sp., found in the ovary of the pumpkinseed (Lepomis gibbosus) and the golden shiner (Noremigonus crysoleucas) respectively from Algonquin Park, Ontario, are described using light and electron microscopy. Ovoid cysts of S. ovophila measured up to 500 pm in length. Monosporic pseudoplasmodia were ovoid or ellipsoid in shape and measured up to 12.5 pm in length. Spores were 7.2–8.4 pm long × 6.0–7.0 pm wide (in sutural plane) × 7.4–8.2 pm thick (perpendicular to sutural plane), with two subspherical polar capsules of equal size measuring 2.7–3.2 × 2.6–3.1 pm and each of which contained a polar filament with 6–7 coils. The spore had a straight sutural ridge which protruded slightly at the anterior end and contained two uninucleate sporoplasms. The spore valve had ornate folds on the posterior end. Cysts of M. algonquinensis ranged from ovoid to elongated ellipsoid in shape and measured up to 800 pm in length. Mature spores measured 13.G15.7 pm long × 10.1–12.1 pm wide × 5.0–6.9 pm thick. with two pyriform polar capsules of equal size measuring 5.1–5.5 pm × 2.5–2.9 pm, each of which contained a polar filament with 4–6 coils. The spores of M. algonquinensis had smooth valves, a straight sutural ridge and a distinct small intercapsular appendix.
The Effects of Entamoeba histolytica Lysates on Human Colonic Mucins1
Authors: Spice William M. , Ackers John P.
Published: May 2007

Detergent lysates of Entamoeba histolytica trophozoites contained high levels of β‐N acetyl‐D‐glucosaminidase. β‐N acetyl‐D‐galactosaminidase and α‐D‐galactosidase activity, and lower but significant levels of five other glycosidases. Although these activities should have been capable of largely degrading the oligosaccharide side‐chains of human colonic mucin, in fact only about one third of high MW mucin was degraded in 72 h and trypsin alone produced a similar effect. There was no evidence that these glycosidases were excreted and we conclude that they are unlikely to represent significant virulence factors for E. histolytica.
Monophyly of Endosymbiont Containing Trypanosomatids: Phylogeny versus Taxonomy
Authors: Hollar Laura , Lukeš Julius , Maslov Dmitri A.
Published: May 2007

To obtain additional information on the phylogenetic relationships within the family Trypanosomatidae (order Kinetoplastida), we have sequenced the small subunit ribosomal RNA genes from the endosymbiont containing species Herpetomonas roitmani TCC080, Herpetomonas sp. TCC263, Crithidia oncopelti ATCC 12982 and a partial large subunit rRNA gene from H. roitmani. The small subunit sequences in the two isolates of Herpetomonas are very similar but not identical, and so are their restriction digest profiles of kinetoplast DNA. The size of minicircles in both isolates is 4.2 kilobases. The inferred ribosomal RNA phylogenetic trees shows the genera Herpetomonas and Crithidia as polyphyletic. Endosymbiont‐bearing herpetomonads cluster with the endosymbiont‐bearing crithidias and a blastocrithidia to form a monophyletic clade, whereas the endosymbiont‐free members of these genera are found elsewhere in the tree. These data support the hypothesis of a monophyletic origin of endosymbiosis in trypanosomatid evolution and also suggest that a taxonomic revision is needed in order to better describe the natural affinities in this family.
Functional Conservation of Calreticulin in Euglena gracilis
Authors: Navazio Lorella , Nardi Maria C. , Pancaldi Simonetta , Dainese Paola , Baldan Barbara , Fitchette‐Lainé Anne‐Catherine , Faye Loïc , Meggio Flavio , Mariani Paola , MARTIN WILLIAM
Published: May 2007

Calreticulin is the major high capacity, low affinity Ca2+ binding protein localized within the endoplasmic reticulum. It functions as a reservoir for triggered release of Ca2+ by the endoplasmic reticulum and is thus integral to eukaryotic signal transduction pathways involving Ca2+ as a second messenger. The early branching photosynthetic protist Euglena gracilis is shown to possess calreticulin as its major high capacity Ca2+ binding protein. The protein was purified, microsequenced and cloned. Like its homologues from higher eukaryotes, calreticulin from Euglena possesses a short signal peptide for endoplasmic reticulum import and the C‐terminal retention signal KDEL, indicating that these components of the eukaryotic protein routing apparatus were functional in their present form prior to divergence of the euglenozoan lineage. A gene phytogeny for calreticulin and calnexin sequences in the context of eukaryotic homologues indicates i) that these Ca2+ binding endoplasmic reticulum proteins descend from a gene duplication that occurred in the earliest stages of eukaryotic evolution and furthermore iii that Euglenozoa express the calreticulin protein of the kinetoplastid (trypanosomes and their relatives) lineage, rather than that of the eukaryotic chlorophyte which gave rise to Euglena's plastids. Evidence for conservation of endoplasmic reticulum routing and Ca2+ binding function of calreticulin from Euglena traces the functional history of Ca2+ second messenger signal transduction pathways deep into eukaryotic evolution.
Monocercomonas sp.: Cytochemistry and Fine Structure of Freeze‐Fractured Membranes
Authors: Diniz José Antonio P. , Benchimol Marlene
Published: May 2007

Monocercomonas sp. from the wood‐snake Tropidophis melanurus was studied using fast freezing of alive and fixed cells followed by freeze‐fracture and deep‐etching. Cytochemistry for enzymes (acid phosphatase, neutral phosphatase, and thiaminopyrophosphatase) and for carbohydrates and endocytosis of gold‐labeled albumin were also performed. The Golgi complex is formed by 12‐14 cisternae with typical cis and trans faces connected to a network of tubular and cisternal structures, and is positive for thiaminopyrophosphatase at the trans face. Intraluminal filamentous structures are seen connecting the two faces of the cisternae of the Golgi complex. Lysosomes appeared to contain acid and neutral phosphatases. Cytochemistry showed that lysosomes predominate among the unidentified vacuoles in the cytoplasm. Some vesicles are involved in the endocytic pathway, while others are derived from the Golgi complex. Hydrogenosomes have a rod‐like or dumb‐bell shape. Two of the anterior flagella present rosettes, when observed in replicas of freeze‐fractured material, formed by circular arrangement of intramembranous particles on both P and E faces. The other anterior and the recurrent flagella do not show such rosettes but showed ribbon‐like arrays of particles at the point where they emerge from the cell body.
Diversity In Symbiotic Dinoflagellates (Pyrrhophyta) from Seven Scleractinian Coral Species: Restriction Enzyme Analysis of Small Subunit Ribosomal RNA Genes
Authors: Darius H. Taiana , Dauga Catherine , Grimont Patrick A. D. , Chungue Eliane , Martin Paul M. V.
Published: May 2007

ABSTRACT The diversity of symbiotic dinoflagellates (SD) from seven coral species (Fungia scutaria, Fungia paumotensis, Lep‐tastrea transversa, Pavona cactus, Pocillopora verrucosa, Montastrea curia, and Acropora fonnosa) was studied in a restricted geographical area, the Lagoon of Arue on the island of Tahiti. Their diversity was explored by small subunit ribosomal RNA gene (SSU rDNA) restriction fragment length polymorphism (RFLP). After a nested amplification with SD specific primers, RFLP analyses were performed directly and after a cloning step. The diversity of these different SSU rDNA was estimated in respect to possible technical artifacts. In an axenic culture of SD from the coral Galaxea fascicularis, both heterogeneous SSU rDNAs and artifact molecules were observed as in our SD samples. According to the number of patterns observed, corals Fungia paumotensis, Leptastrea transversa. Pavona cactus, Montastrea curia, and Acropora fonnosa contained one class of SD SSU rDNAs. whereas Fungia scutaria and Pocillopora verrucosa contained three and two classes of SD SSU rDNAs respectively. In the limited geographic area studied. SD from different coral species shared the same pattern, except SD from Montastrea curta, which showed a unique pattern. In addition to the possibility of SD flux among different coral species, specific mechanisms could also be involved in the establishment of a symbiosis.
Fibrillarin, A Conserved Pre‐ribosomal RNA Processing Protein of Giardia
Authors: Narcisi Elizabeth M. , GLOVER Claiborne V. C. , Fechheimer Marcus
Published: May 2007

ABSTRACT The flagellated protozoan Giardia has been shown by 16S rRNA sequence analysis to be one of the most primitive of the eukaryotes. A gene encoding the protein fibrillarin, a pre‐rRNA processing protein implicated in rRNA methylation and ribosome assembly, has been isolated. A genomic DN'A fragment 1,240 base pairs long containing an open reading frame of 981 base pairs (327 amino acids) was sequenced. The deduced protein sequence of 35.3 kDa is similar to other known fibrillarin sequences. The Giardia sequence includes the amino terminal glycine/arginine rich domain characteristic of eukaryotic fibrillarins but is unique in having a large number of acidic residues in this domain. Phylogenetic analysis of the available fibrillarin sequences is consistent with the assignment of Giardia to a position close to the most primitive of the eukaryotes. A monoclonal antibody to yeast fibrillarin crossreacts with a 36 kDa polypeptide from Giardia on western blots and diffusely stains both nuclei of the organism by immunofluorescence microscopy. This result is consistent with the absence of well defined nucleoli in this organism. The evolutionary conservation of fibrillarin suggests an important function for this protein in ribosome biosynthesis, and this function appears to be maintained from the archaebacteria, which lack a nucleus, to Giardia, which contains a nucleus but lacks a prominent nucleolus, to higher mammals, which have both nucleus and nucleolus.
The Content of Alternative Oxidase of Euglena Mitochondria is Increased by Growth in the Presence of Cyanide and is not Cytochrome o.
Authors: Devars Silvia , Hernandez Rosa , Covian Raul , Garcia‐Horsman Arturo , Barquera Blanca , Moreno‐Sanchez Rafael
Published: May 2007

ABSTRACT A study of the effect of respiratory inhibitors on O2 uptake of Euglena gracilis mitochondria, isolated from cells grown in the presence of cyanide or with ethanol as carbon source, was undertaken. The contents of cytochrome c oxidase and alternative oxidase were also determined. Inhibition of respiration by antimycin and cyanide was only partial and it was dependent on the oxidizable substrate used. Succinate oxidation was the most sensitive to cyanide whereas lactate oxidation was the most resistant. Cell growth in the presence of cyanide or with ethanol as carbon source brought about an enhanced content of alternative oxidase without a concomitant increase in cytochrome aa3 content. However, a correlation between cyanide‐resistant respiration and alternative oxidase content was not found. Analysis of heme types in mitochondrial membranes revealed the absence of heme O. The data suggest the presence of an inducible alternative oxidase in Euglena mitochondria which has high resistance to cyanide and contains heme B. A close relationship between Euglena alternative oxidase and bacterial quinol oxidases containing B‐type heme is proposed.
Phylogenetic Identification of the Symbiotic Hypermastigote Trichonympha agilis in the Hindgut of the Termite Reticulitermes speratus Based on Small‐Subunit rRNA Sequence
Authors: Ohkuma Moriya , Ohtoko Kuniyo , Grunau Christoph , Moriya Shigeharu , Kudo Toshiaki
Published: May 2007

The phylogeny of a symbiotic hypermastigote Trichonympha agilis (class Parabasalia; order Hypermastigida) in the hindgut of the lower termite Reticulitermes speratus was examined by a strategy that does not rely on cultivation. From mixed‐population DNA obtained from the termite gut, small subunit (16S‐like) ribosomal RNA sequences were directly amplified by the polymerase chain reaction method using primers specific for eukaryotes. Comparative sequence analysis of the clones revealed two kinds of sequences, one from the termite itself and the other from a symbiotic protist. A fluorescent‐labeled oligonucleotide probe for the latter sequence was designed and used in whole‐cell hybridization experiments to provide direct visual evidence that the sequence originated from a large hypermastigote in the termite hindgut, Trichonympha agilis. According to the phylogenetic trees constructed, the hypermastigote represented one of the deepest branches of eukaryotes. The hypermastigote along with members of the order Trichomonadida formed a monophyletic lineage, indicating that this hypermastigote and trichomonads shared a recent common ancestry.
Molecular Characterization of a Plasmodium chabaudi Erythrocyte Membrane‐Associated Protein with Glutamate‐Rich Tandem Repeats
Authors: Giraldo Luis E. , Grab Dennis J. , Wiser Mark F.
Published: May 2007

The malarial parasite dramatically affects the structure and function of the erythrocyte membrane by exporting proteins that specifically interact with the host membrane. This report describes the complete sequence and some biochemical properties of a 93‐kDa Plasmodium chabaudi chabaudi protein that interacts with the host erythrocyte membrane. Approximately 40% of the deduced protein sequence consists of tandem repeats of 14 amino acids that are rich in glutamic acid residues. Comparison of the repeat sequences from two different P. c. chabaudi strains derived from the same initial isolate revealed an exact duplication of 294 nucleotides suggesting a recent gel electrophoresis and gel filtration chromatography suggest that the protein is a long rod‐shaped or fibrillar. protein. Attributes shared between the 93‐kDa protein, some P. falciparum proteins with glutamate‐rich tandem repeats, and cytoskeletal proteins suggest that these parasite proteins function as cytoskeletal proteins that possibly stabilize the erythrocyte membrane.
Vanadate Affects Nuclear Division and Induces Aberrantly‐Shaped Cells during Subsequent Cytokinesis in Tetrahymena
Authors: NILSSON JYTTE R.
Published: May 2007

ABSTRACT Sodium orthovanadate at 0.1–5.0 mM affected cell proliferation of Tetrahymena in a dose‐dependent manner. At 1 h the cell increment was 76–12% of the control (100%), but after lag periods in 1–5 mM the growth rate remained at 76% of control in 0.1 mM vanadate and at 64–61% of control in 0.2–5.0 mM vanadate. Endocytosis was affected in both a time‐ and dose‐dependent manner; an increasing number of cells did not form vacuoles. Cell motility increased initially in 0.1 mM vanadate but decreased later as it did in 0.5–2.0 mM vanadate where the proportion of immobile cells increased with time. Cell divisions occurred at all concentrations but macronuclear elongation was disturbed and subsequent cytokinesis resulted in daughter cells containing the entire G2 macronucleus, a large or small portion of it, or no nucleus at all. Moreover, odd cell shapes appeared with time. The size of the cell and nucleus increased but there was great variation with disturbed cytoplasm/nucleus ratios. Treated cells had dilated rough endoplasmic reticulum that included dense material, presumed to be vanadate. which was not seen in control cells. Scant amounts of dense material were found in dense granules, small vacuoles, and abundantly in contractile vacuoles. It is argued that interference with proper microtubular function is the main effect of vanadate.
Trypanosoma rangeli—In vitro Metacyclogenesis and Fate of Metacyclic Trypomastigotes after Infection to Mice and Fibroblast Cultures
Authors: TANOURA KIYOSHI , YANAGI TETSUO , GARCIA VIVIAN MATTA DE , KANBARA HIROJI
Published: May 2007

ABSTRACT High metacyclogenesis was induced when freshly‐isolated Trypanosoma rangeli from humans were grown in a modified liver‐infusion‐tryptose medium and transferred into the medium overlaid on mouse fibroblasts at 27° C in a 5% CO2 atmosphere. Such in yitro‐generated metacyclic trypomastigotes could induce a significantly high and constant parasitemia in both ICR and SCID mice for a period of about a week but thereafter the parasitemia gradually decreased. Histological examination could not detect any tissue‐forms of T. rangeli in various organs of SCID mice. On the other hand, two long‐maintained stocks of T. rangeli produced lower metacyclogenesis and only latent parasitemia in both strains of mice. When these populations were incubated in fibroblast cultures at 37° C in a 5% CO2 atmosphere, only trypomastigotes survived for two to three weeks without proliferation, while other forms, mainly epimastigotes, soon began to swell and degenerate. Electron microscopy showed that most surviving trypomastigotes had the basket‐like conformation of the kinetoplasts. This is characteristic of the non‐dividing trypomastigote stage of T. cruzi, and suggests that T. rangeli trypomastigotes may survive long periods in the blood without proliferation.
Affinity‐Purification of Concanavalin A‐Binding Ciliary Glycoconjugates of Starved and Feeding Tetrahymena thermophila
Authors: DRISCOLL COLLEEN , HUFNAGEL LINDA A.
Published: May 2007

ABSTRACT Development of mating competency in Tetrahymena thermophila requires starvation for at least 70 min in low ionic strength buffer. Pair formation between conjugating cells is blocked at early stages by the lectin Concanavalin A (Con A). To investigate the role of Con A‐binding proteins in this induced cellular change and in pairing, and to confirm and extend an earlier study from our laboratory, a method was developed for preparation of Con A‐binding proteins from ciliary membrane‐rich fractions of T. thermophila. Con A‐binding ciliary proteins were prepared from non‐starved and starved cells from two wild type strains and a mating mutant, RH179EI. Comparison of these proteins by SDS‐PAGE revealed an overall reduction in number of wild‐type bands after starvation. In particular, a major band at 28 kDa was present in non‐starved cells and absent in starved cells. However, in the mating mutant, no change in banding profile was seen after starvation: the 28 kDa band was present in both non‐starved and starved cells. Thus, Con A‐binding ciliary membrane proteins undergo a major change during starvation‐induced development of mating competency in wild‐type T. thermophila. In contrast, the mutant differed from wild‐type in overall composition of its ciliary Con A‐binding glycoproteins and in the response of these proteins to starvation, suggesting that it may be deficient in its ability to be initiated by starvation. Our results are consistent with the hypothesis that a change affecting ciliary membrane Con A‐binding proteins is essential for the cellular response to mating signals.