bluuebunny/crossref_metadata_2025 huggingface dataset:
Linked Genes for Calmodulin and E2 Ubiquitin‐Conjugating Enzyme in Trichomonas vaginalis
Authors: KEELING PATRICK J. , DOHERTY‐KIRBY AMANDA L. , TEH EVELYN M. , DOOLITTLE W. FORD
Published: May 2007

ABSTRACT In searching the genomes of early‐diverging protists to study whether the possession of calmodulin is ancestral to all eukaryotes, the gene for calmodulin was identified in Trichomonas vaginalis. This flagellate is a member of the Parabasalia, one of the earliest lineages of recognized eukaryotes to have diverged. This sequence was used to isolate a homologous 1.250‐kb fragment from the T. vaginalis genome by inverse polymerase chain reaction. This fragment was also completely sequenced and shown to contain the 3′ end of the single‐copy calmodulin gene and the 3′ end of a gene encoding a protein with high similarity to E2 ubiquitin‐conjugating enzymes, a family which has previously only been identified in animals, plants, and fungi. Phylogenetic analysis of 50 members of the E2 family distinguishes at least nine separate subfamilies one of which includes the T. vaginalis E2‐homologue and an uncharacterized gene from yeast chromosome XII.
Detailed Analyses of Individual Neutral Lipid Classes of Pneumocystis
Authors: KALLAM KATHRYN A. , KANESHIRO EDNA S.
Published: May 2007

SUMMARY Individual neutral lipid classes of Pneumocystis carinii carinii were isolated and purifed by thin‐layer chromatography. The fatty acids in steryl esters, triglycerides, free fatty acids, diglycerides, and monoglycerides were quantified by gas‐liquid chromatography. The fatty acid compositions of these lipids were similar to those of the neutral lipid classes in whole rat lung controls, unlike comparable studies of phospholipid classes. The free fatty alcohols of rat lung controls and P. carinii were also identified and quantified; only saturated fatty alcohols were detected.
Induction of Blocks in Nuclear Divisions and Overcondensation of Meiotic Chromosomes with Cycloheximide During Conjugation of Tetrahymena thermophila
Authors: KACZANOWSKI ANDRZEJ , KACZANOWSKA JANINA
Published: May 2007

During conjugation, the micronucleus of Tetrahymena thermophila undergoes five consecutive nuclear divisions: meiosis, third prezygotic division (pregamic mitosis) and two postzygotic mitoses of the synkaryon. The four products of the synkaryon differentiate into macronuclear anlagen and new micronuclei and the old macronucleus is resorbed. The protein synthesis inhibitor cycloheximide, applied during conjugation, induced several developmental blocks. Pairs shifted to the drug during early meiotic prophase (stages I–III) were arrested at prophase. Cycloheximide applied to cells at pachytene (stages IV‐VI) to metaphase arrested the conjugants at the stage of modified prometaphase/metaphase with overcondensed, swollen bivalents. In contrast to other systems, in the presence of cycloheximide, separation of chromatids, decondensation of chromosomes and exit from metaphase I were inhibited in both diploid and haploid cells. Pairs shifted to the drug after metaphase I were arrested at postmeiotic interphase after completing one nuclear cycle. The same rule applied to the subsequent cycle; then cells were arrested at the stage of pronuclei, and those pairs with functional pronuclei and synkarya were arrested at the stage of two products of the first postzygotic division (pronuclei were not arrested in nuclear transfer and karyogamy). Only pairs with two products of the first postzygotic division were arrested at the same stage after the cycloheximide treatment. Pairs shifted to cycloheximide during the second postzygotic division were arrested in development of macronuclear anlagen and resorption of old macronuclei. The postmeiotic conjugants pulse‐treated with cycloheximide (2 h) yielded heterokaryons retaining parental macronuclei (i.e. they exhibited macronuclear retention).
Micronuclear and Macronuclear Sequences of a Euplotes crassus Gene Encoding a Putative Nuclear Protein Kinase
Authors: HALE CYNTHIA A. , JACOBS MARY ELLEN , ESTES HEATHER G. , GHOSH SUSMITA , KLOBUTCHER LAWRENCE A.
Published: May 2007

The sequences of a 1.8‐kbp macronuclear DNA molecule (V3), and the majority of its micronuclear counterpart, are reported. The macronuclear V3 DNA molecule contains an open reading frame that is interrupted by a single intron, while the micronuclear copy is interrupted by four internal eliminated sequences, one of which is located within the intron. The predicted protein product of the macronuclear V3 gene is a 471‐amino acid polypeptide that is very similar to a group of protein‐serine/threonine kinases from both plant and animal species, some of whose members appear to be involved in cell cycle or growth control.
Influence of Pneumocystis carinii on Nitrite Production by Rat Alveolar Macrophages1
Authors: SIMONPOLI ANNE‐MARIE , RAJAGOPALAN‐LEVASSEUR PREMAVATHY , BRUN‐PASCAUD MONIQUE , BERTRAND GUYLENE , POCIDALO MARIE‐ANNE , GIRARD PIERRE‐MARIE
Published: May 2007

ABSTRACT Nitrite production by rat alveolar macrophages was studied to determine the role of L‐arginine oxidation in the interaction between these cells and Pneumocystis carinii. Alveolar macrophages from rats obtained from two different breeders were used: rats from Janvier breeder had latent P. carinii infection, while those from Charles River breeder were bred in a germ‐free environment. Pneumocystis carinii increased in vitro nitrite generation by unstimulated alveolar macrophages from Janvier rats only, and this was blocked by NG‐monomethyl‐L‐arginine. Incubation of cells from Janvier and Charles River rats with lipopolysaccharide and/or interferon‐gamma increased nitrite production to a similar extent. Pneumocystis carinii partially decreased nitrite release by activated alveolar macrophages, and this was still inhibited by NG‐monomethyl‐L‐arginine. In the presence of P. carinii, superoxide dismutase used as a superoxide anion scavenger had no effect on nitrite production by activated cells. These results show that prior exposure to P. carinii leads to nitric oxide production by rat alveolar macrophages. Although the magnitude of this production seems to be moderate, it is of biological significance since cells of P. curinii‐naive rats do not generate nitrite whereas those of latently infected rats do.
Riboprinting: A Tool for the Study of Genetic Diversity in Microorganisms1
Authors: CLARK C. GRAHAM
Published: May 2007

ABSTRACT. Classical morphology‐based methods of taxonomic and phylogenetic analysis are inadequate in many groups of structurally simple eukaryotes. Molecular methods can generate data independently of the complexity of the organisms’ morphology. Riboprinting is one such technique, and involves restriction enzyme analysis of polymerase chain reaction amplified small subunit ribosomal RNA genes. The utility of the method is illustrated with examples from several genera of intestinal and bloodstream parasites. Among the applications of riboprinting are the detection of cryptic genetic variation within species, organism misidentifications and culture mix‐ups, independent verification of DNA sequences, and the rapid generation of data useful in phylogenetic analyses.
Ultrastructure and Organization of the Cytoskeleton in Oxymonas, an Intestinal Flagellate of Termites
Authors: BRUGEROLLE GUY , KÖNIG HELMUT
Published: May 2007

ABSTRACT. Oxymonas has the characteristic structures and organization of other oxymonads including two separated pairs of basal bodies/flagella, a preaxostylar lamina, a paracrystalline axostyle, and an absence of mitochondria and Golgi. Like other Oxymonadinae genera it possesses a long proboscis, the rostellum which is terminated by the holdfast. Like the genera Pyrsonympha and Streblomastix, Oxymonas possesses a holdfast which permits it to attach to the cuticle of the termite hind‐gut. This holdfast is subdivided into rhizoids and is filled with microfilaments. The rostellum is variable in length and contains two distinct microtubular bundles. One bundle is composed of convoluted microtubular ribbons which originate at the base of the holdfast and extend posteriorly along the rostellum and before penetrating into the cell body. The second bundle is composed of flexuous free microtubules which originate at different levels of the rostellum, increasing in number from top to base. They occupy the axial part of the rostellum and incorporate into the axostylar rows at the basal body/flagellar level. Microtubules of the paracrystalline axostyle are cross‐linked by bridges forming parallel rows like in the contractile axostyles of other oxymonads such as Pyrsonympha and Saccinobaculus. Most of the microtubules of the axostyle originate at the flagellar/preaxostylar level but some originate from the axial flexous free microtubules of the rostellum, as indicated above. The possibility of an extension/retraction of the rostellum, suggested by other authors, is discussed.
The Occurrence of Biogenic Calcian Struvite, (Mg, Ca)NH4PO4.6H2O, as Intracellular Crystals inParamecium
Authors: GROVER JOHN E. , ROPE ALAN F. , KANESHIRO EDNA S.
Published: May 2007

ABSTRACT.Intracellular crystals are conspicuous refractile “inclusion bodies” commonly found in many protozoans, but very few have been identified mineralogically. We have isolated crystals from axenically grown mass cultures ofParamecium tetraurelia, and purified them using differential centrifugation. The crystals’ structure and chemistry were analyzed using x‐ray powder diffraction and energy‐dispersive electron microprobe techniques. The morphology was studied by means of scanning electron microscopy. The crystals were identified as the orthorhombic mineral, calcian struvite, (Mg, Ca)NH4PO4.6H2O. Struvite fromP. tetraureliaexhibited a variety of crystal habits, including hemimorphic forms, epitactic overgrowths and several types of twins. A linear correlation between computed hydration number and Mg content suggests that the crystal composition may reflect the range of conditions under which struvite nucleation and growth occur. The mineral struvite also occurs in association with guano and other rich organic products, and can be biologically induced to precipitate extracellularly. Extracellular struvite has been well characterized in pathogenic calculi (kidney stones) of humans and cats, where precipitation is enhanced by bacterial urease activity that produces ammonia in the urinary tract. This is the first study demonstrating that struvite is also biologically controlled to form as an intracellular mineral. These crystals may have formed within lipid‐rich, membrane‐bound vesicles inParamecium.
Up‐Regulation of Actin mRNA and Reorganization of the Cytoskeleton in Entamoeba histolytica Trophozoites
Authors: MANNING‐CELA REBECA , MEZA ISAURA
Published: May 2007

ABSTRACT. Actin mRNA levels were measured in Entamoeba histolytica trophozoites after experimentally inducing changes in the organization of the cytoskeleton. The treatment of trophozoites with forskolin, N6,2′‐O‐dibutyryl‐adenosine 3′:5′‐cyclic monophosphate, and phorbol myristate acetate induced the organization of actin into multiple dots and defined structures with a concomitant increase in F‐actin content. Cytochalasin D elicited polarization of the structured actin and formation of aggregates, as well as an increment in F‐actin. Simultaneously, up‐regulation of actin mRNA levels was produced by all the drugs. De novo synthesis of actin mRNA, as measured by nuclear run‐ons, showed increased transcription of actin mRNA. On the other hand, treatment of cells with actinomycin D blocked the elevation of actin mRNA synthesis induced by forskolin, dibutyryl cyclic AMP, or cytochalasin D whereas, the increment induced by PMA was not affected. These data indicate a regulatory control of actin mRNA synthesis at the transcriptional level by forskolin, dibutyryl cyclic AMP and cytochalasin D, and transcriptional as well as post‐transcriptional controls by phorbol myristate acetate. The experiments presented here suggest the possibility that, regulation of actin mRNA transcription in E. histolytica trophozoites is linked to growth conditions, that are accompanied by reorganization of the actin cytoskeleton and thus, related to the motility and invasiveness of the parasite.
The Products and Pathways of Glucose Catabolism in Herpetomonas muscarum ingenoplastis and Herpetomonas muscarum muscarum
Authors: REDMAN CHRISTOPHER A. , COOMBS GRAHAM H.
Published: May 2007

ABSTRACT. The products and pathways of glucose catabolism in the insect trypanosomatids Herpetomonas muscarum ingenoplastis and Herpetomonas muscarum muscarum have been studied with the aim of elucidating how both organisms are able to proliferate well under aerobic and anaerobic conditions. When incubated in medium containing glucose as the only exogenous carbon source, catabolism was found to be fermentative in both cases. Acetate was a major product of both organisms while H. m. ingenoplastis produced more ethanol and propionate and less succinate than H. m. muscarum. Ethanol production by H. m. ingenoplastis decreased both under anaerobic conditions and in the presence of elevated CO2 concentrations, whereas succinate and propionate release by this organism were greater in high CO2 and anoxia, respectively. Succinate production by H. m. muscarum was greatest under anaerobic conditions in elevated CO2 whereas propionate was only a minor product. The same four products were released during growth of the organisms in complex medium, but the relative proportions differed suggesting that other substrates were being used. Both organisms contained enzymes of the glycolytic and pentose phosphate pathways, but while all activities of the TCA cycle were present in H. m. muscarum. NAD‐linked isocitrate dehydrogenase, α‐ketoglutarate dehydrogenase, succinate CoA synthase and succinate dehydrogenase were not detected in H. m. ingenoplastis. Fumarate reductase activity was present in both organisms. The data presented suggest that CO2‐fixation and reverse flux through the TCA cycle may be important factors that enable the organisms to undergo anaerobiosis.
On the Identity of the Amoeboflagllates Didascalus throntoni and Adelphamoeba galeacystis
Authors: JONCKHEERE JOHAN F. DE , BROWIN SUSAN , ROBINSON BERT S.
Published: May 2007

ABSTRACT. Didascalus thorntoni, Singh 1952 has been classified alternately as a separate genus or as a species of Naegleria. In the 18th edition of the American Type Culture Collection catalogue it is classified as Naegleria thorntoni. To resolve the question of its identity we have used riboprinting and sequencing of the small subunit ribosomal DNA. The results indicate that D. thorntoni does not belong to the genus Naegleria. The sequence of the small subunit ribosomal DNA differs only in 20 nucleotides (1%) from that of the Paratetramitus jugosus. The difference is much smaller than between some species of Naegleria. Therefore, it is not clear whether D. thorntoni should be considered as a species of Paratetramitus or as a separate genus. The strain used in different laboratories as the type strain of Adelophamoeba gleacystis has been identified as a Naegleria strain. We believe that the type strain of A. galeacystis was mislabeled prior to submission to the American Type Culture Collection and to the Culture Collection of Algae and Protozoa. A recent isolate, which on the basis of morphology was identified as a strain of A. Galeacystis, has the identical small subunit ribosomal DNA sequence as D. throntoni. Our results prove Page was right when he stated that Adelphamoeba might be a synonym of Didascalus.
Ribosomal DNA Sequence of Nucleospora salmonis Hedrick, Groff and Baxa, 1991 (Microsporea: Enterocytozoonidae): Implications for Phylogeny and Nomenclature
Authors: DOCKER MARGARET F. , KENT MICHAEL L. , HERVIO DOMINIQUE M. L. , KHATTRA JASWINDER S. , WEISS LOUIS M. , CALI ANN , DEVLIN ROBERT H.
Published: May 2007

ABSTRACT. Rules of zoological nomenclature, morphological data, and robosomal DNA sequence data support the validity of the genus Nucleospora, and its placement in the family Enterocytozoonidae. Although Nucleospora exhibits most of the distinguishing morophological characteristics of the family Enterocytozoonidae Cali and Owne, 1990, the distinctively different hosts (fish and humans, respectively) and sites of development (the nuclei of immature blood cells and the cytoplasm of enterocutes) supprot the placement Nucleospora and Enterocytozoon into separate genera. Ribosomal DNA sequence comparisons between Nucleospora salmonis and Enterocytozoon bieneusi showed 19.8% genetic divergece in the large and small subunit regions. Although more inter‐ and intrageneric divergence between the two species is sufficiently larg to deter suppression of the genus Nucleospora as a junior synonym of Enterocytozoon. A polymerase chain reaction test for the detection of N. salmonis in chinook salmon (Oncorhynchus tshawytscha), based on N. salmonis‐specific ribosomal DNA sequence, is described.
Phylogeny of the Rumen Ciliates Entodinium, Epidinium and Polyplastron (Litostomatea: Entodiniomorphida) Inferred from Small Subunit Ribosomal RNA Sequences
Authors: WRIGHT ANDRÉ‐DEENIS G. , DEHORITY BURK A. , LYNN DENIS H.
Published: May 2007

ABSTRACT. Three complete 18S ribosomal RNA gene sequences from the rumen ciliates, Entodinium coudatum (1,639 bp), Epidinium caudarum (1,638 bp), and Polyplastron multivesiculatum (1,640 bp) were determined and confrimed in the opposite direction. Trees produced using maximum parsimony and distance‐matrix methods (lest squares and neighbour‐joining). with strong bootstrap support, depict the rumen ciliates as a monophyletic group, Entodinium caudatum is the earliest branching rumen ciliate. However, Entodiniwn simplex does not pair with En. caudatum, but rather with Polyplastron multivesiculatum. Signature sequences for these rumen ciliates reveal that the published SSrRNA gene sequence from En. simplex is in fact a Polyoplastron species. The free‐living haptorian ciliates, Loxophyllum, Homalozoon and Spathidium (Subclass Hoptoria), are monophyletic and are the sister group to the rumen cilates. The litostomes (class Litostomatea), consisting of the haptorians and the rumen ciliates, are also a monophyletic group.
Ultrastructural Effects of Lactoferrin Binding on Giardia lamblia Trophozoites
Authors: TURCHANY JILL MARIE , MCCAFFERY J. MICHAEL , ALEY STEPHEN B. , GILLIN FRANCES D.
Published: May 2007

ABSTRACT. Lactoferrin and its derived N‐terminal peptide may be important host defenses against Giardia lamblia. We showed earlier that lactoferrin and the derived peptides have potent giardicidal activity in vitro. Using indirect immunofluorescence, we now demonstrate binding of lactoferrin and the peptides to the live trophozoite surface. Iron strongly inhibited binding of lactoferrin, and decreased binding of the peptides, while certain divalent metal ions decreased binding of all forms by about half. Lactoferrin and the peptedes caused striking and complex morphologic changes in the trophozoite plasmalemma, endomembranes and cytoskeleton, and increases the electron density of the lysosome‐like peripheral vacuoles.
Activities of Enzymes of Carbohydrate and Energy Metabolism of the Spores of the Microsporidian, Nosema grylli
Authors: DOLGIKH VIACHESLAV V. , SOKOLOVA JULIA J. , ISSI IRMA V.
Published: May 2007

ABSTRACT. The presence of 14 enzymes was investigated using purified spores of the microsporidian Nosema grylli from fat body of the crickets Gryllus bimaculatus. Glucose 6‐phosphate dehydrogenase (EC 1.1.1.49), phosphoglucomutase (EC 5.4.2.2), phosphoglucose isomerase (EC 5.3.1.9), fructose 6‐phosphate kinase (EC 2.7.1.11), aldolase (EC 4.1.2.13), 3‐phosophoglycerate kinase (EC 2.7.2.3), pyruvate kinase (EC 2.7.1.40) and glycerol 3‐phosphate dehydrogenase (EC 1.1.1.8) were detected with activities of 15 ± 1, 7 ± 1, 1,549 ± 255, 10 ± 1, 5 ± 1, 16 ± 4, 6 ± 1 and 16 ± 2 nmol/min. mg protein, respectively. Hexokinase (EC 2.7.1.1), NAD‐dependent malate dehydrogenase (EC 1.1.1.37), malic enzyme (EC 1.1.1.40), lactate dehydrogenase (EC 1.1.1.27), alcohol dehydrogenase (EC 1.1.1.1) and succinate dehydrogenase (EC 1.3.99.1) were not detectable. These results suggest the catabolism of carbohydrates in microsporidia occurs via the Embden‐Meyerhof pathway. Glycerol 3‐phosphate dehydrogenase may reoxidize NADH which is produced by glyceraldehyde 3‐phosphate dehydrogenase in glycolysis.
Ultrastructure of Spironucleus barkhanus N. Sp. (Diplomonadida: Hexamitidae) from Grayling Thymallus thymallus (L.) (Salmonidae) and Atlantic Salmon Salmo salar L. (Salmonidae)
Authors: STERUD ERIK , MO TOR A. , POPPE TRYGVE T.
Published: May 2007

ABSTRACT. A hexamitid flagellate Spironucleus barkhanus n. sp., from the lumen of the gut and gall bladder of wild grayling Thymallus thymallus, and from muscle abscesses of farmed Atlantic salmon Salmo salar from Norway, is described by light, scanning and transmission electron microscopy. The flagellate was axenically cultured in trypticase, yeast extract, iron serum medium. Live trophozoites from axenic cultures incubated at 5° C, measure 11–20 x 6–14 μm. The flagellates show a typical bi‐radial symmetry. Each recurrent flagellum is almost completely surrounded by a striated lamina. In the posterior end the lamina widens, appearing heart shaped in transverse section. Accompanying each recurrent flagellum are three narrow bands of microtubules, following the longitudinal groove created by the incomplete closure of the striated lamina. The recurrent flagella emerge posterio‐medially through cytostome openings halfway surrounded by crescent‐shaped ridges, oriented in opposite directions in the two openings. The position and adornment of the cytostome openings, and the arrangement and number of the microtubules accompanying the recurrent flagella, distinguish Spironucleus barkhanus n. sp. from previously described species of Spironucleus.
Trichodina ctenophorii N. Sp., a Novel Symbiont of Ctenophores of the Northern Coast of the Gulf of Mexico
Authors: ESTES ANNE M. , REYNOLDS BARBARA S. , MOSS ANTHONY G.
Published: May 2007

ABSTRACT. Peritrich ciliates of the genus Trichodina are internal or external symbionts of invertebrate and vertebrate hosts. We describe here Trichodina ctenophorii n. sp., a symbiont of Mnemiopsis mccraydii and Beroë ovata (Phylum Ctenophora). The morphology of fixed and living specimens is revealed by silver impregnation, scanning electron microscopy, and differential interference microscopy. Distinguishing features of Trichodina ctenophorii include a denticular morphology composed of falcate, blunt‐tipped blades, and long, straight thorns, with five pins per denticle. Trichodina ctenophorii is found only on the comb plates of these ctenophores. To the best of our knowledge, this is the first report of a trichodinid from the Gulf of Mexico and the first associated with ctenophores.
Oxygen Uptake and Antioxidant Responses of the Free‐Living Diplomonad Hexamita sp.
Authors: BIAGINI GIANCARLO A. , SULLER MARC T. E. , FINLAY BLAND J. , LLOYD DAVID
Published: May 2007

ABSTRACT. The free‐living anaerobic flagellate Hexamita sp. was observed to actively consume O2 with a Km O2 of 13 μM. Oxygen consumption increased lineraly with O2 tension up to a threshold level of 100 μM, above which it was inhibited. Oxygen uptake was supported by a number of substrates but probably not coupled to energy conservation as cytochromes could not be detected spectro‐photometrically. In addition, inhibitors specific for respiratory chain components did not significantly affect O2 uptake. Respiration was however, partially inhibited by flavoprotein and iron‐sulfur protein inhibitors. NAD(P)H supported O2 consumption was measured in both particulate and soluble fractions; this activity was partially inhibited by quinacrine. A chemosensory response was observed in cells exposed to air, however no response was observed in the presence of superoxide dismutase plus catalase. Catalase and nonspecific peroxidase activity could not be detected, but superoxide dismutase activity was present. Superoxide dismutase was sensitive to NaN3 and H2O2 but not KCN, suggesting a Fe prosthetic group. Flow cytometric analysis revealed that thiol levels in live cells were depleted in the presence of t‐butyl H2O2. The observed NADPH‐driven glutathione reductase activity is believed to recycle oxidized thiols in order to re‐establish reduced thiol levels in the cell. The corresponding thiol cycling enzyme glutathione peroxidase could not be detected. The ability to withstand high O2 tensions (100 μM) would enable Hexamita to spend short periods in a wider range of habitats. Prologed exposure to O2 tensions higher than 100 μM leads to irreversible damage and cell death.
Ultrastructural Variability in the Locomotor Cortex of the Ciliated Protozoa, Mytilophilus pacificae
Authors: SALEHI‐ASHTIANI KOUROSH , ANTIPA GREGORY A.
Published: May 2007

ABSTRACT. Mytilophilus pacificae is an endocommensal ciliate found in the mantle cavity of the Pacific Coast mussel Mytilus californianus. In this paper we report our findings on pellicular organization of this species. Transmission and scanning electron microscope examination of the somatic cortex revealed that a number of different types of kinetids, i.e. monokinetids, dikinetids, and polykinetids are found in the locomotor cortex. The type and distribution of the kinetids are described. Surprisingly, the locomotor region was found to be highly variable among individuals with respect to its kinetid distribution; each cell appears to have its own characteristic kinetid pattern. Some cells have mostly monokinetids and dikinetids in their locomotor cortex, while others may have dikinetids and polykinetids but very few monokinetids. In contrast to the locomotor region, the thigmotactic field (a region specialized for attachment) is exclusively composed of dikinetids and shows no heterogeneity. The finding of ultrastructural variability in the locomotor cortex was unexpected since, in the view of the structural conservation hypothesis, the somatic cortex is seen as a “stable” element. These observations raise new questions with regard to cortical pattern formation in this organism.
A Lectin‐like Molecule is Discharged from Mucocysts of Tetrahymena pyriformis in the Presence of Insulin
Authors: KOVÁCS PÉTER , MÜLLER WERNER E. G. , CSABA GYÖRGY
Published: May 2007

ABSTRACT. By use of a monoclonal antibody directed against purified lectin from the sponge Geodia cydonium it was demonstrated that the mucocysts of Tetrahymena pyriformis contain a substance immunologically similar to that found in G. cydonium. In extracts of T. pyriformis the monoclonal antibody recognizes a 36 kDa protein; binding could be abolished by adsorption of the antibody with (i) crude extract, (ii) purified lectin from G. cydonium and (iii) a 29 aa long peptide. In addition the data show that 10‐6 M of insulin causes first the release of mucocyst material, which reacts with the lectin antibody, and second its subsequent redistribution on the surface of the somatic cilia and the oral field.
Alternate Junctions and Microheterogeneity of Tlr1, a Developmentally Regulated DNA Rearrangement in Tetrahymena thermophila
Authors: PATIL NAMRATA S. , HEMPEN PAULA M. , UDANI RUPA A. , KARRER KATHLEEN M.
Published: May 2007

ABSTRACT. A large number of developmentally regulated DNA rearrangements occur during the development of the macronucleus in Tetrahymena thermophila, Tlr1 is a deletion element which has large inverted repeats near the rearrangement junctions and deletes more than 13 kbp of internal DNA. Previous analysis of caryonidal lines revealed alternate left junctions for the Tlr1 rearrangement in B strain cells. We show here that C2 strain Tetrahymena also use alternate rearrangement junctions. We have mapped and sequenced two additional rearrangement variants and find that both the left and right can vary over a range of approximately 200 bp. We also demonstrate the presence of sequence microheterogeneity in the most commonly found Tlr1 rearrangement product.
Comments: Overveiw of the 5th International Workshop on Pneumocystic and the 5th General Meeting of the European Concerted Action of Pneumocystis Research
Authors: KANESHIRO EDNA S. , WAZLZER PETER D.
Published: May 2007

The major highlights of the meetings were the initiation of efforts ot assign different species names to certain Penumocystis jorganism, and the invitations for international participation in a project to map and sequence the genome of P. carinii. The oral and poster presentations demostrated important advances have been achieved in the past year.
Programmed DNA Degradation and Nucleolar Biogenesis Occur in Distinct Organelles During Macronuclear Development in Tetrahymena
Authors: SMOTHERS JAMES F. , MADIREDDI MALAVI T. , WARNER FRED D. , ALLIS C. DAVID
Published: May 2007

ABSTRACT. Programmed DNA rearrangements, including DNA degradation, characterize the development of the soma from the germline in a number of developmental systems. Pddl p (programmed DNA degradation 1 protein), a development‐specific polypeptide in Tetrahymena, is enriched in developing macronuclei (anlagen) and has been implicated in DNA elimination and nucleolar biogenesis. Here, immunocytochemistry and fluorescent in situ hybridization (FISH) were employed to follow Pddl p and two nucleolar markers (Nopp52 and rDNA) during macronuclear development. Both Pdd 1p and Nopp52 localize to subnuclear structures, each of which resemble nucleoli. However, while true nucleoli form and persist during development, Pdd 1p‐positive structures are only present for a brief period of macronuclear differentiation. Accordingly, two distinct organelles can be recognized in anlagen: (1) Pdd 1p‐positive structures, which lack Nopp52 and rDNA, and (2) developing nucleoli which contain rDNA and Nopp52 but lack Pdd 1p. Taken together with recent data corroborating Pdd 1p's role in DNA elimination, we favor the hypothesis that Pdd 1p structures are unique, short‐lived organelles, likely to function in programmed DNA degradation and not in nucleolar biogenesis.
Ultrastructure of Infection, Development and Gametocyst Formation of Ascogregarina taiwanensis (Apicomplexa: Lecudinidae) in Its Mosquito Host, Aedes albopictus (Diptera: Culicidae)
Authors: CHEN WEI‐JUNE , CHIA‐YI CHOW  , WU SHU‐TSUAN
Published: May 2007

ABSTRACT. The life history of the protozoan parasite Ascogregarina taiwanensis in mosquito larvae (Aedes albopictus, collected in southern Taiwan) was shown to consist of two consecutive stages—intracellular and extracellular. Light microscopy showed that most trophozoites moved into the Malpighian tubules and developed into giant trophozoites during the first day pupa. The locomotion may be associated with bristle‐like ridges of the trophozoite. The stage for sexual reproduction, i.e. the gamete, was then formed by segmentation of the giant trophozoite and twisting off the anucleate extremities of the body. Sexual reproduction occurred via fertilization by fusion of two resulting gametes, presumably two opposed sexes. The fused gametes finally generate the formation of the gametocyst, within which oocysts develop by budding from the cytoplasmic mass. This type of sexual reproduction has not been reported previously in any gregarine protozoa. We here proposed it as a new hypothesis for further elucidation of the protozoan reproduction.
Effects of Organic Solvents on the Coupling Between ATP Hydrolysis and Sliding of Microtubules in Axonemes from Chlamydomonas Flagella
Authors: NOGUCHI MUNENORI , INOUE HIROSHI , ATAGO TOSHIHIRO , NAKAMURA SHOGO
Published: May 2007

ABSTRACT. The effects of organic solvents on the ATPase activity and the sliding disintegration of axonemes from Chlamydomonas were investigated. The axonemal ATPase was markedly activated by methanol accompanying with marked inhibition of the sliding disintegration of axonemes. On the contrary, glycerol inhibited the ATPase activity without serious inhibition of the sliding disintegration. As far as the axonemes are not irreversibly denatured by extremely high concentration of solvents, the effects of solvents both on the ATPase and the ability of sliding are reversible. Therefore, the inhibition of sliding accompanied by the activation of ATPase is probably due to an inability to couple the hydrolysis of ATP to sliding between dynein and microtubule in the presence of methanol. The axonemal ATPase was less sensitive to vanadate inhibition after exposure to methanol. This indicates that methanol makes the dyneinADP.Pi complex unstable and increases product release. On the other hand, glycerol and ethylene glycol seem to stabilize the force generation responsible for the sliding through stabilizing the dynein.ADP.Pi complex.
Blood Parasites of the Iguanid Lizard, Ctenosaura similis from Costa Rica, with a Description of Hepatozoon gamezi N. Sp.
Authors: DESSER SHERWIN S.
Published: May 2007

ABSTRACT. Five species of four genera of hematozoa were observed in the blood of 15 Ctenosaura similis from the Guanacaste Conservation Area in northwestern Costa Rica. The most prevalent parasite, which occurred in all the lizards, was designated a new species, Hepatozoon gamezi, on the basis of light and electron microscopic data on its gamonts and hepatic meronts. In addition, a second species of Hepatozoon, one of Schellackia and one of Trypanosoma are described and illustrated, but not named. Microfilariae which conform with the description of Oswaldofilaria brevicaudata were recorded in 40% of the lizards. Problems in distinguishing and naming new species of certain hemoparasites solely on the basis of peripheral blood films are discussed.
Microsporidia of the Genus Trachipleistophora—Causative Agents of Human Microsporidiosis: Description of Trachipleistophora anthropophthera N. Sp. (Protozoa: Microsporidia)
Authors: Vávra Jiří , Yachnis Anthony T. , Shadduck John A. , Orenstein Jan M.
Published: May 2007

Trachipleistophora anthropophthera n. sp., was found at autopsy in the brain of one and in the brain, kidneys, pancreas, thyroid, parathyroid, heart, liver, spleen, lymph nodes, and bone marrow of a second patient with AIDS. The parasite is similar to the recently described T. hominis Hollister, Canning, Weidner, Field. Kench and Marriott, 1996, in having isolated nuclei, meronts with a thick layer of electron dense material on the outer face of their plasmalemma and sporogony during which spores are formed inside a thick‐walled sporophorous vesicle. In contrast to T. hominis, this species is dimorphic as it forms two kinds of sporophorous vesicles and spores: Type I‐round to oval polysporous sporophorous vesicle. 7‐10 μm in size, usually with eight spores (3.7 × 2.0 μm), thick endospores, subterminal anchoring disc and anisofilar polar filaments forming seven thicker and two thinner terminal coils. This type of sporophorous vesicle is associated with 25‐30 nm filaments extending into the host cell cytoplasm. Type II—smaller, bisporous sporophorous vesicle (4‐5 times 2.2‐2.5 μm) with two, nearly round, thin‐walled spores, 2.2‐2.5 × 1.8‐2.0 μm in size, having 4‐5 isofilar coils. No outside filamentous elements are associated with the bisporous sporophorous vesicle. Both types of sporophorous vesicles were common in the infected brain tissue and could be found within the same cell. The newly described species, together with T. hominis and previously reported Pleistophora‐like parasites from human muscle, likely represent a group of closely related human microsporidia.
Mechanisms of Microsporidial Cell Division: Ultrastructural Study on Encephalitozoon hellem
Authors: Bigliardi Elisa , Riparbelli Maria Giovanna , Selmi Maria Gloria , Lanzarini Paolo , Corona Silvia , Gatti Simonetta , Scaglia Massimo , Sacchi Luciano
Published: May 2007

The mitotic process in microsporidian Encephalitozoon hellem. a known human pathogen, has been studied with the aim of elucidating some ultrastructural aspects of its nuclear division. The presence of a nuclear spindle, of “electrondense spindle plaques” associated with the nuclear envelope and of cytoplasmic double walled vesicles are reported. We suggest that these “electrondense spindle plaques” serve as foci for intranuclear and cytoplasmic microtubule arrangements, similar to the microtubule organizing centers within the centrosomes of animal cells. The extent to which the microsporidial division process is comparable with that of more familiar eukaryotes such as yeast cells is discussed.
Ribosomal DNA Fragments Enhance the Stability of Transfected DNA in Entamoeba histolytica
Authors: Dhar Suman K. , Vines Richard R. , Bhattacharya Sudha , Petri William A.
Published: May 2007

ABSTRACT Genetic manipulation of Entamoeba histolytica is limited by the inability to express foreign genes at high levels. We tested whether sequences from the E. histolytica rDNA episome, present in 200 copies per cell, could act to stabilize the episomal transfection vector pTCV1. Ligation of the rDNA transcription unit, or sequences downstream of the rDNA transcription unit, increased pTCV1 copy number and stability and conferred additional zones of DNA replication. Sequences upstream of the rDNA transcription unit dramatically destabilized pTCV1. These experiments give additional insights into the mechanism of DNA replication and provide for E. histolytica a set of transfection vectors with unique properties.
Spasmin and a Putative Spasmin Binding Protein(s) Isolated from Solubilized Spasmonemes1
Authors: Asai Hiroshi , Ninomiya Takashi , Kono Rin‐Ichiro , Moriyama Yasushige
Published: May 2007

ABSTRACT The amino acid composition and hydrophobicity scale (hydropathy) of calcium‐binding proteins contained in the contractile spasmoneme of Carchesium polypinum was compared with other calcium‐binding proteins from eukaryotes. Spasmins which may hind at most 4 calcium ions simultaneously and initiate spasmoneme contraction cooperatively belong to a super family of proteins including; centrin/caltractin and calmodulin. Based on chemical modification of tryptophan and methionine, these residues are involved in contraction but the spasmin proteins contain little or none of these amino acids. Based on this evidence, it is suggested that another, non‐calcium binding protein(s) is involved in spasmoneme contraction.
Comparison of Sequence Differences in a Variable 23S rRNA Domain among Sets of Cryptic Species of Ciliated Protozoa
Authors: Nanney David L. , Park Chaeryung , Preparata Rosamaria , Simon Ellen M.
Published: May 2007

ABSTRACT Studies were undertaken to discover the relative molecular distances separating some familiar forms of ciliated protozoa, and the genetic species they include. Sequences of 190 bases of the D2 domain of the large ribosomal nucleic acid molecule were obtained by polymerase chain reaction from protists of three distinctive groups of ciliated protozoa‐Colpoda, Paramecium and Tetrahymena. Evolutionary trees were constructed for each set of sequences using the PHYLOGEN 1.0 string programs. All three groups of ciliates manifested large molecular diversity among strains difficult or impossible to distinguish morphologically. The largest single evolutionary distance within a group was the 75 differences separating Tetrahymena paravorax from the other tetrahymenids. The largest mean distance for a group was the 21.2 for the colpodids. In all the protist groups the large molecular diversity is obscured by morphological conservatism associated with constraints of ancient designs. The molecular diversity within morphotypes argues for long evolutionary coexistence of species differentiated from each other in significant physiological, ecological, or nutritional ways.
Stable Patterns of Allelic Diversity at the Merozoite Surface Protein‐1 Locus of Plasmodium falciparum in Clinical Isolates from Southern Vietnam
Authors: Ferreira Marcelo U. , Liu Qing , Zhou Mian , Kimura Masatsugu , Kaneko Osamu , Thien Huvnh Van , Isomura Shin , Tanabe Kazuyuki , Kawamoto Fumihiko
Published: May 2007

ABSTRACT The extent of allelic diversity at the Merozoite Surface Protein‐1 locus of Plasmodium falciparum (PfMSP‐1) was examined in isolates collected from symptomatic patients living in a mesoendemic area in southern Vietnam. The variable blocks 2, 4 and 10 were typed by polymerase chain reaction and 24 PfMSP‐1 gene types were defined as unique combinations of allelic types detected in each variable block. Nineteen PfMSP‐1 gene types were identified and 182 parasite populations were fully typed among 102 isolates. Forty‐eight (47%) patients harbored more than one typed parasite population, and one patient had at least eight genetically distinct subpopulations. As previously shown in the same endemic area, recombination between blocks 4 and 10 was significantly less frequent than expected from random assortment of allelic types. The distribution of PfMSP‐1 gene types, however, did not differ significantly from that observed in isolates collected in the same area 17‐24 mo before the present study. Furthermore, the prevalence of the most common gene types and the average number of different gene types harbored by the same host did not decrease with age. This argues against the prominence of frequency‐dependent immune selection of PfMSP‐1 polymorphisms in this parasite population.
Structure and Development of a Marine Actinosporean, Sphaeractinomyxon ersei n. sp. (Myxozoa)
Authors: Hallett Sascha L. , O'Donoghue Peter J. , Lester Robert J. G.
Published: May 2007

ABSTRACT This is the first ultrastructural study of the development of a marine actinosporean and of a species belonging to the genus Sphaeractinomyxon Caullery & Mesnil, 1904. S. ersei n. sp. is described from a limnodriloidine oligochaete, Doliodrilus diverticulatus Erséus, 1985, from Moreton Bay. Queensland, Australia. Development is asynchronous, there being all stages from two‐celled pansporoblasts through to mature spores present simultaneously within a host. Spores develop in groups of eight within pansporoblasts in the coelom and when mature are located also in the intestinal lumen. The primordial spore envelope and sporoplasm develop separately in the pansporoblast until the polar filament is formed within the polar capsule and the capsulogenic cell cytoplasm has begun to degrade. The sporoplasm then enters the spore through a separated valve junction. Mature spores are triradially symmetrical with three centrally located polar capsules and a single binucleate sporoplasm with about 46 germ cells. Swellings or projections of the epispore do not occur when spores exit the host and contact sea water.
Incorporation In Vivo and In Vitro of Radiolabeled Sphingolipid Precursors into Paramecium tetraurelia Lipids
Authors: Matesic Diane F. , Erwin Joseph A. , Kaneshiro Edna S.
Published: May 2007

ABSTRACT Paramecium tetraurelia contains high concentrations of ethanolamine sphingolipids, especially in its ciliary membrane. Three ethanolamine sphingophospholipids with different long chain bases (dihydrosphingosine, sphingosine and phytosphingosine), and their phosphonyl analogs, were previously identified and characterized. In the present study, radiolabeling experiments on lag‐ and log‐phase cells were performed to investigate the extent of sphingolipid biosynthetic capacities of the ciliate. Long chain bases of sphingolipids are formed by an initial condensation reaction of serine with a fatty‐coenzyme A. Thus, radiolabeled palmitic acid, stearic acid and serine were used as precursor compounds in these experiments. The results indicated that (1) sphingolipid precursors were incorporated into every major lipid fraction. (2) ethanolamine sphingophosphonolipids accumulated faster than the ethanolamine sphingophospholipids, (3) in contrast to these sphingolipids, the glycerolipid, phosphatidyethanolamine. accumulated faster than its phosphono analog, and (4) palmitic acid, but not stearic acid, was incorporated into the long chain bases of ethanolamine sphingophospho‐ and sphingophosphonolipids. consistent with an earlier report demonstrating that these lipids contain only C,g long chain bases. Since P. tetraurelia takes up serine and other water‐soluble substrates very slowly, and catabolizes fatty acids rapidly, label is randomized in intact cells. Thus, cell‐free protocols provide useful experimental systems for studies of sphingolipid biosynthesis than do intact organisms, when the uptake of precursor substrates are slow.
Characterization of a Monoclonal Antibody and a cDNA for Polyubiquitin ofAmoeba proteus
Authors: Lee So Young , Kim Hyun Joon , Yoo So Yeun , Ahn Tae In
Published: May 2007

A monoclonal antibody was obtained that reacts with many different proteins (14‐200 kDa) ofAmoeba proteus.By indirect immunofluorescence microscopy we found the antigens to be dispersed throughout the cytoplasm but were more concentrated in the nucleus. The antibody cross‐reacted with proteins ofTetrahymena, Xenopusembryo, and mouse macrophages. Using the antibody as a probe we cloned a cDNA of 1.2 kb coding for ubiquitin in five repeats. Amino acid sequences of ameba's polyubiquitin showed the most variations among the nineteen polyubiquitins of other organisms compared. The well‐conserved20Ser and55Thr residues were replaced with Gly and Ser. respectively. The28Ala residue found in most organisms was replaced with Gln or Glu in the amoeba. Amoebae contained two ubiquitin‐mRNAs that could be detected by Northern blot analysis using the cDNA as a probe. In an analysis for specificity, the antibody reacted with polyubiquitin and ubiquitin‐fusion proteins larger than 14 kDa but not with monomeric ubiquitin. The antibody is a useful probe in the detection and characterization of proteins ubiquitinated in response to cellular stresses.
Interface‐Mediated Death of Unconditioned Tetrahymena Cells: Effect of the Medium Composition
Authors: HAGEMEISTER JOACHIM J. , GRAVE MICHAEL , KRISTIANSEN THOMAS BIRK , ASSAAD FAHED , HELLUNG‐LARSEN PER
Published: May 2007

ABSTRACT We have previously shown that the cell death of Tetrahymena thermophila in low inocula cultures in a chemically‐defined medium is not apoptotic. The death is caused by a cell lysis occurring at the medium‐air interface and can be prevented by the addition of insulin or Pluronic F‐68. Here, we report that cell death can also be caused by the medium. The specific effects of several medium constituents were tested in the presence and absence of an interface. Four of the 19 amino acids (arginine, aspartic acid, glutamic acid, and histidine in millimolar concentration) as well as Ca2+ (68 μM) and Mg2+ (2 mM) and trace metal ions (micromolar concentrations) are all sufficient to induce the interface‐mediated death. The effect of the amino acids and the salt ions Ca2+ and Mg2+ can be abolished by the addition of insulin (10‐6 M) or Pluronic F‐68 (0.01% w/v), whereas insulin/Pluronic F‐68 only postpones the death induced by trace metal ions. On the basis of our findings, a new recipe for a chemically‐defined medium has been formulated. Single cells can grow in this medium in the presence of medium‐air interface without any supplements.
Polymorphisms at the Topoisomerase II Gene Locus Provide More Evidence for the Partition of Trypanosoma cruzi into Two Major Groups
Authors: SANTOS WAGNER G. DOS , BUCK GREGORY A.
Published: May 2007

ABSTRACT We have dissected the topoisomerase II gene of members of the two recently characterized subgroups of Trypanosoma cruzi to obtain further evidence to support this dichotomy of isolates in this important parasite. Pulsed field gel electrophoresis showed a striking heterogeneity in the molecular karyotypes of the strains analyzed. Southern analysis of these chromosome gels also showed heterogeneity in the size and number of chromosomes containing the topoisomerase II gene. Analysis of DNA restriction fragment length polymorphisms of the topoisomerase II gene also showed two principal patterns consistent with the two previously characterized groups. Finally, the sequences of portions of the topoisomerase II genes from members of the T. cruzi groups showed two distinct patterns, again consistent with the previous grouping of this parasite. Thus, this work clearly supports previous observations suggesting an ancient divergence of known T. cruzi isolates into two main branches.