bluuebunny/crossref_metadata_2025 huggingface dataset:
Cold Microgradients Elicit Adaptive Behavior in Isotropically Cooled, Inert Populations of Oxytricha bifaria (Ciliophora, Hypotrichida)
Authors: BARBANERA FILIPPO , ERRA FABRIZIO , RICCI NICOLA
Published: July 2005

ABSTRACT. To complete our investigations on the oriented behavioral response of isotropically cooled, inert populations of Oxytricha bifaria to a warm thermal gradient, their physiological potentialities under cold microgradient conditions arising at 8.5°C were studied. We monitored the behavior of the experimental populations, both at the level of the passing cold wave front, and afterwards when the thermal gradient stabilized, evaluating (i) their distribution in general, (ii) their relative centroids, (iii) the percentage of both backward creeping and immobile ciliates, and (iv) the numerical indices and rates of their creeping tracks. At the arrival of the cold wave front, the oxytrichas react immediately to the thermal stimulus, creep backwards at very high velocity along uninterrupted linear tracks, and thus move away from the cooling source. No specific behavioral response was ever observed in the static microgradient conditions. At 8.5°C, despite their inertness, the ciliates are still able to behave adaptively, reacting immediately and orientatedly, once a directional factor (the cold‐repelling thermal gradient) arises in an isotropic environment. This is similar to their behavior in the symmetric warm attracting thermal gradient.
Determination of the Copy Number of the Nuclear rDNA and Beta‐tubulin Genes of Pneumocystis carinii f. sp. hominis Using PCR Multicompetitors
Authors: NAHIMANA AIMABLE , FRANCIOLI PATRICK , BLANC DOMINIQUE S. , BILLE J. , WAKEFIELD ANN E. , HAUSER PHILIPPE M.
Published: July 2005

ABSTRACT. Multiple copies of a gene may lead to difficulty in the interpretation of typing results because polymorphism of the copies may wrongly lead to the conclusion that different types are present in a specimen. To determine the copy number per genome of the nuclear rDNA and beta‐tubulin genes analyzed for the typing of Pneumocystis carinii f. sp. hominis, we developed a strategy based on the use of the same multicompetitor molecule in two different quantitative‐competitive PCRs, one for the gene under study and the other for a reference single copy gene, allowing direct comparison of the results of both PCRs. Control experiments showed that the strategy was sensitive enough to detect duplication of a gene. The copy number of the nuclear rDNA operon was determined by amplification of the intron of the 26S rDNA gene and that of the beta‐tubulin by amplification of the region surrounding the intron no. 6. The method was first tested on P. c. carinii, the special form commonly infecting rats. Pneumocystis c. carinii was found to contain a single copy of the rDNA operon. The method was then applied to P. c. hominis. The results confirmed that P. c. hominis genome contains a single copy of the nuclear rDNA and beta‐tubulin genes.
Neutral Lipids, their Fatty Acids, and the Sterols of the Marine Ciliated Protozoon, Parauronema acutum
Authors: SUL DONGGEUN , KANESHIRO EDNA S. , JAYASIMHULU KOKA , ERWIN JOSEPH A.
Published: July 2005

ABSTRACT. The neutral lipids and their fatty acids and the sterol fractions of the marine ciliated protozoon, Parauronema acutum, were characterized. The neutral lipids consisted of triglycerides (30%), sterols (29%), free fatty acids (24%), steryl esters (9%), and diglycerides (8%) and small amounts of fatty alcohols. The fatty acid profiles of these lipids were very similar although quantitative differences were detected. Saturated fatty acids, primarily 14: 0, 16: 0, and 18: 0 constituted 20‐30% of the total. Unsaturated fatty acids containing one to three double bonds, primarily 18: 1(9), 18: 2 (9,12), 18: 3 (9, 12, 15) and 20: 3 (11, 14, 17), constituted 35–50% of the total. Highly unsaturated fatty acids, 18: 4 (6, 9, 12, 15), 20: 5 (5, 8, 11, 14, 17) and 22: 6 (4, 7, 10, 16, 19), constituted 16–25% of the total. The fatty alcohols consisted of 14: 0 (2%), 16: 0 (66%), 18: 0 (3%), 20: 0 (8%), and 22: 0 (21%). The sterols of Parauronema acutum consisted of cholesterol (53%), campesterol (32%), desmosterol (7%), and β‐sitosterol (8%).
Comparison of Small Subunit Ribosomal RNA Gene and Internal Transcribed Spacer Sequences Among Isolates of the Intranuclear Microsporidian Nucleospora salmonis
Authors: GRESOVIAC STEPHANE J. , KHATTRA JASWINDER S. , NADLER STEVEN A. , KENT MICHAEL L. , DEVLIN ROBERT H. , VIVARES CHRISTIAN P. , DE LA FUENTE EDUARDO , HEDRICK RONALD P.
Published: July 2005

ABSTRACT. Nucleospora salmonis is an intranuclear microsporidian associated with a proliferative disorder of the lymphoid cells of captive salmonid fish in the northwestern and northeastern regions of North America, in France, and in Chile. Newer diagnostic approaches have used the polymerase chain reaction (PCR) to detect the parasite in fish tissues. The target sequences for these assays lie in the small subunit ribosomal RNA (ssu rRNA) gene or internal transcribed spacer (ITS) as determined from N. salmonis from chinook salmon (Oncorhynchus tshawytscha) from the Pacific Northwest of North America. The lack of sequence data on parasites from diverse geographic origins and hosts led us to compare several isolates of N. salmonis. There was a high degree of similarity in the ssu rDNA sequences (> 98%) among all the isolates of N. salmonis examined, regardless of host or geographic origin. The greatest sequence differences were found between isolates from the Pacific regions of America. Isolates from Chile shared sequences with one or both geographic groups from North America. A similar distribution of sequence types was observed when ITS‐1 sequences of selected isolates were analyzed. Sequence data from two N. salmonis‐like isolates from marine non‐salmonid fish showed one closely related and the second less closely related to N. salmonis isolates from salmonid fish. These results provide evidence for a homogeneous group of aquatic members of the genus Nucleospora found among salmonid fish (N. salmonis) that can be detected using diagnostic PCR assays with ssu rDNA target sequences. The presence of parasites related to N. salmonis among marine fish suggests a potentially broad host and geographic distribution of members of the family Enterocytozoonidae.
Prevalence of a Trypanosomatid in the Southern Green Stink Bug, Nezara viridula
Authors: FUXA JASON E. , FUXA JAMES R. , RICHTER ARTHUR R. , WEIDNER EARL H.
Published: July 2005

ABSTRACT. The southern green stink bug, Nezara viridula (L.), and certain of its host plants were examined to determine the prevalence and biological characteristics of an intestinal trypanosomatid. Promastigotes with short (≤ 17.5 μm excluding flagellum) and long forms (≥ 25.0 μm) usually infected < 50% of the bugs before August and > 50% (maximum 95%) during August‐October, but prevalence was not host‐density dependent. The flagellate was detected in adults and in all nymphal instars, at all sampling sites where at least 10 bugs were captured, and in bugs from all host plants sampled (soybean, red clover, vetch). Of bugs with flagellates, 27% were heavily infected (> 20 flagellates per 160× microscope field). Weights of infected and uninfected adults did not differ. Live flagellates were detected in bug feces and in one stem of red clover. When bugs were fed soybean pods, tomatoes, or snap beans in the laboratory, only once were flagellates detected in plant tissue (snap beans). The flagellate was cultured in modified Medium 199. This flagellate is prevalent in N. viridula populations in Louisiana and apparently does not cause significant pathological effects in N. viridula or its host plants, including soybean.
Experimental Amebiasis: Immunohistochemical Study of Immune Cell Populations
Authors: GHOSH PRABIR K. , VENTURA JAVIER , GUPTA SADHNA , SERRANO JESUS , TSUTSUMI VICTOR , ORTIZ‐ORTIZ LIBRADO
Published: July 2005

ABSTRACT. Distribution of immune cell populations was studied in a C3H/HeJ mouse model of intestinal amebiasis from 5 to 60 days post‐inoculation with Entamoeba histolytica, using immunoperoxidase techniques. At various time intervals, the ceca from mice were fixed in 10% formalin, dehydrated, embedded and sectioned at 5 μm. Sections were incubated with conjugated peroxidase‐labelled antibodies to mouse IgA, IgM, and IgG. Color was developed with 3, 3′‐diaminobenzidine tetrahydrochloride (DAB)/H2O2 solution. CD3, CD4, and CD8 cells, as well as neutrophils were detected by reacting with biotin‐conjugated anti‐mouse CD3, CD4, CD8, and CD11 monoclonal antibodies, followed by their incubation with avidin‐peroxidase and color development with DAB/H2O2 solution. Erythrocin B and toluidine blue were used to stain eosinophils and Mast cells, respectively. It was observed that the IgA+ plasma cell was the dominating immune cell present in the mucosa, although eosinophils, neutrophils, CD3+, CD4+, CD8+, IgM+, IgG+ cells and Mast cells were also seen. Results of this study suggest that infiltration of immune cells at the mucosal surface during intestinal amebiasis might be important in the defense against this parasite.
A Survey of Flagellate Diversity at Four Deep‐Sea Hydrothermal Vents in the Eastern Pacific Ocean Using Structural and Molecular Approaches
Authors: ATKINS MICHAEL S. , TESKE ANDREAS P. , ANDERSON O. ROGER
Published: July 2005

ABSTRACT. Eighteen strains of flagellated protists representing nine species were isolated and cultured from four deep‐sea hydrothermal vents: Juan de Fuca Ridge (2,200 m), Guaymas Basin (2,000 m), 21° N (2,550 m) and 9° N (2,000 m). Light and electron microscopy were used to identify flagellates to genus and, when possible, species. The small subunit ribosomal RNA genes of each vent species and related strains from shallow‐waters and the American Type Culture Collection were sequenced then used for comparative analysis with database sequences to place taxa in an rDNA tree. The hydrothermal vent flagellates belonged to six different taxonomic orders: the Ancyromonadida, Bicosoecida, Cercomonadida, Choanoflagellida, Chrysomonadida, and Kinetoplastida. Comparative analysis of vent isolate and database sequences resolved systematic placement of some well‐known species with previously uncertain taxonomic affinities, such as Ancyromonas sigmoides, Caecitellus parvulus and Maxxixteria marina. Many of these vent isolates are ubiquitous members of marine, freshwater, and terrestrial ecosystems worldwide, suggesting a global distribution of these flagellate species.
Genetic and Environmental Factors Affecting Mating Type Frequency in Natural Isolates of Tetrahymena thermophila
Authors: ARSLANYOLU MUHITTIN , DOERDER F. PAUL
Published: July 2005

ABSTRACT. In Tetrahymena thermophila mating type alleles specify temperature sensitive frequency distributions of multiple mating types. A‐like alleles specify mating types I, II, III, V and VI, whereas B‐like alleles specify mating types II through VII. We have characterized the mating type distributions specified by several A‐ and B‐like genotypes segregated by genomic exclusion from cells isolated from a pond in northwestern Pennsylvania. The B‐like genotypes are alike in specifying very low frequencies of mating type III, but differ with respect to the frequencies of other mating types, particularly II and VII. An A‐like genotype specifies a high frequency of mating type III and is unstable in successive generations for the expression of mating type II, suggesting a possible modifier. Inter se crosses performed at 18°C, 28°C and 34°C showed that each genotype specifies a frequency distribution that is uniquely affected by temperature. No mating type was affected the same way by temperature in all genotypes. In A/B heterozygotes, the B‐like genotype exhibited partial dominance. The genotypes described here differ significantly from previously described genotypes from the same pond, indicating that there are numerous mating type alleles. For frequency‐dependent selection to equalize mating type frequencies, it must act not only on complex multiple alleles but also on the response of mating type alleles to temperature.
Phylogenetic Relationships of the Subclass Peniculia (Oligohymenophorea, Ciliophora) Inferred from Small Subunit rRNA Gene Sequences
Authors: STRÜDER‐KYPKE MICHAELA C. , WRIGHT ANDRÉ‐DENIS G. , FOKIN SERGEI I. , LYNN DENIS H.
Published: July 2005

ABSTRACT. Peniculine ciliates have been recognized as a distinct higher taxon of ciliates for almost 50 years. However, phylogenetic relationships within the Subclass Peniculia are still unsettled. To contribute to our understanding of their phylogeny and provide evidence for the position of Urocentrum turbo, we sequenced its small subunit (SS) rRNA gene and the SSrRNA genes from Lemhadion bullinum, Frontonia sp., Paramecium caudatum, Paramecium multimicronucleatum, Paramecium putrinum, and Parameciumwoodruffi. Urocentrum turbo was the only one of these species not to exhibit a shortened Helix E10_1, which we conclude characterizes the “higher” peniculines. Except for U. turbo, the peniculines are strongly supported as a monophyletic clade with Lembadion, Frontonia, and Paramecium species forming separate and strongly supported clades by bootstrap analysis using distance matrix, maximum parsimony, and maximum likelihood methods. Urocentrum turbo is associated with different lineages, depending upon the analysis used. The Paramecium species form at least four clades with the Paramecium aurelia subgroup being the most derived. We conclude that the Subclass Peniculia should be divided into two orders, the Order Urocentrida and Order Peniculida, with the latter order having two suborders, the Suborder Frontoniina and Peniculina. We place U. turbo with the peniculines because of shared morphological and stomatogenetic features.
Cyst Formation in a Freshwater Strain of the Choanoflagellate Desmarella moniliformis Kent
Authors: LEADBEATER BARRY S. C. , KARPOV SERGUEI A.
Published: July 2005

ABSTRACT. Cyst formation in a freshwater strain of the colonial freshwater Choanoflagellate Desmarella moniliformis Kent (Protozoa; Choanoflagellida) has been studied with light and electron microscopy for the first time. Batch cultures inoculated with motile vegetative cells start to produce cysts within 3 days during the exponential phase of growth. Cyst production proceeds until in late stationary phase there is a preponderance of cysts. Transfer of cysts to fresh medium results in limited excystment. Encystment involves the production of electron‐dense fibrillar wall material, firstly around the neck of the cell and then around the posterior end. As the wall material is deposited the neck of the cell elongates and the dictyosome rotates from the horizontal to vertical plane. The number of mitochondrial profiles seen in individual sections of cells increases. Finally the neck of the cell is retracted, the flagellum and collar tentacles are withdrawn, and the bottom of the neck of the cyst wall is sealed with a diaphragm of wall material. Excystment, which has not been observed directly, appears to involve the disruption of the wall at the base of the neck, the remainder of the cyst wall remains intact. Comparisons are made between encystment in Desmarella and cyst development in other protists.
Purification and Specificity of Two α‐Glucosidase Isoforms of the ParasiticProtist Trichomonas vaginalis
Authors: TER KUILE BENNO H. , HRDÝ IVAN , SÁNCHEZ LIDYA B. , MÜLLER MIKLÓS
Published: July 2005

ABSTRACT. Two isoforms of α‐glucosidase were purified from the parasitic protist Trichomonas vaginalia. Both consisted of 103 kDa subunits, but differed in pH optimum and substrate specificity. Isoform 1 had a pH optimum around 4.5 and negligible activity on glucose oligomcrs other than maltose, while isoform 2 with a pH optimum of 5.5 hydrolyzed also such substrates at considerable rates. Neither had activity on glycogen or starch. Isoform 1 had a specific activity for hydrolysis of maltose of 30 U/mg protein and isoform 2 101 U/mg protein. The Km values were 0.4 mM and 2.0 mM, respectively. Isoform 2 probably corresponds to the activity detected on the cell surface.
Timing of Life Cycle Morphogenesis in Synchronous Samples ofSterkiella histriomuscorum.II. The Sexual Pathway
Authors: ADL SINA M. , BERGER JAMES D.
Published: July 2005

ABSTRACT.Isolates ofSterkiella(Oxytrichidae, Stichotrichia, Ciliata) are commonly used to study macronuclear development. These organisms respond to changes in food abundance variably by encystment‐excystment, conjugation, cannibalism or rescaling cell size. An isolateof Slerkiella histriomuscorum(previouslyOxytricha fallax and O. Irifallax) is used because two complementary mating types are available. We provide observations on conjugation in cultures of this isolate. Using synchronous samples of conjugants, the timing of stages of nuclear divisions during conjugation was determined. Following ex‐conjugant cultures over time, the onset of clonal aging and senescence is described. Cells become sexually mature after a brief period of “adolescence”, during which time selfing is possible. Senescent cultures are less vigorous, unable to conjugate and encyst more readily. Excystment survival decreases with clonal age. These results can serve as reference for long‐term cultures of this species and for analysing particular stages of developmental processes during conjugation.
UV‐induced Cell Damage is Species‐specific among Aquatic Phagotrophic Protists
Authors: SOMMARUGA RUBEN , BUMA ANITA G. J.
Published: July 2005

ABSTRACT. The sensitivity to ultraviolet radiation (UVR, 280–400 nm) of ten species of freshwater and marine phagotrophic protists was assessed in short‐term (4 h) laboratory experiments. Changes in the motility and morphology of the cells, as well as direct quantification of DNA damage, were evaluated. The net amount of cyclobutane pyrimidine dimers formed after exposure of the organisms to a weighted dose (Setlow DNA normalized at 300 nm) of 1.7 kJ m−2 was quantified by an immunoassay using a monoclonal specific antibody directed against thymine dimers (T<>Ts). This is the first application of this method to aquatic protists. The results indicated that marine and freshwater heterotrophic nanoflagellates, representatives from the order Kinetoplastida (Bodo caudatus and Bodo sultans, respectively) accumulate significantly higher DNA damage than protists representatives of the orders Chrysomonadida, Cryptomonadida or Scuticociliatida. The high proportion of A:T bases in the unique kinetoplast DNA, may explain the higher accumulation of T<>Ts found in bodonids. Experiments made with B. saltans to study the dynamics of DNA damage accumulation in the presence of UVR and photorepairing light, indicated that the mechanisms of DNA repair in this species are very inefficient. Furthermore, the dramatic changes observed in the cell morphology of B. saltans probably compromise its recovery. Our results show that sensitivity to UVR among aquatic phagotrophic protists is species‐specific and that different cell targets are affected differently among species. While DNA damage in B. saltans was accompanied by motility reduction, altered morphology, and finally mortality, this was not observed in other bodonids as well as in the other species tested.
A New Class and Order of Myxozoans to Accommodate Parasites of Bryozoans with Ultrastructural Observations on Tetracapsula bryosalmonae (PKX Organism)
Authors: CANNING ELIZABETH U. , CURRY ALAN , FEIST STEPHEN W. , LONGSHAW MATTHEW , OKAMURA BETH
Published: July 2005

ABSTRACT. Tetracapsula bryosalmonae, formerly PKX organism, is a myxozoan parasite that causes proliferative kidney disease in salmonid fish. Its primary hosts, in which it undergoes a sexual phase, are phylactolaemate bryozoans. It develops in the bryozoan coelomic cavity as freely floating sacs which contain two types of cells, stellate cells and sporoplasmogenic cells, which become organised as spores. Eight stellate cells differentiate as four capsulogenic cells and four valve cells which surround a single sporoplasmogenic cell. The sporoplasmogenic cell undergoes meiosis and cytoplasmic fission to produce two sporoplasms with haploid nuclei. Sporoplasms contain secondary cells. The unusual development supports previously obtained data from 18S rDNA sequences, indicating that species of Tetracapsula form a clade. It diverged early in the evolution of the Myxozoa, before the radiation that gave rise to the better known genera belonging to the two orders in the single class Myxosporea. The genus Tetracapsula as seen in bryozoans shares some of the characters unique to the myxosporean phase and others typical of the actinosporean phase of genera belonging to the class Myxosporea. However, it exhibits other features which are not found in either phase. A new class Malacosporea and order Malacovalvulida are proposed to accommodate the family Saccosporidae and genus Tetracapsula. Special features of the new class are the saclike proliferative body, valve cells not covering the exit point of the polar filament, lack of a stopper‐like structure sealing the exit, maintenance of valve cell integrity even at spore maturity, absence of hardened spore walls and unique structure of sporoplasmosomes in the sporoplasms.
Comparative Morphology of the Euglenid Pellicle. I. Patterns of Strips and Pores
Authors: LEANDER BRIAN S. , FARMER MARK A.
Published: July 2005

ABSTRACT. In anticipation that improved knowledge of euglenid morphology will provide robust apomorphy‐based definitions for clades, transmission and scanning electron microscopy were used to reveal novel morphological patterns associated with the euglenid pellicle. In some taxa, the number of pellicle strips around the cell periphery reduces as discrete whorls at the anterior and posterior ends of the cell. The number of whorls at either end varies between selected euglenid taxa but is invariant within a taxon. The pattern of strip reduction associated with these whorls is shown to have at least three evolutionarily linked states: exponential, pseudoexponential, and linear. Two general equations describe these states near the posterior end of euglenid cells. Exponential patterns of strip reduction near the anterior end are described by a third equation. In addition, several euglenid taxa were found to possess conspicuous pellicle pores. These pores are arranged in discrete rows that follow the articulation zones between adjacent strips. The number of strips between rows of pores varies between taxa and displays a series of consecutive character states that differ by a power of two. The patterns of pores may not only have phylogenetical and taxonomical value but may provide morphological markers for following strip maturation during cytoskeletal reproduction.
Contributions of the Axostyle and Flagella to Closed Mitosis in the Protists Tritrichomonas foetus and Trichomonas vaginalis
Authors: RIBEIRO KARLA C. , MONTEIRO‐LEAL LUIZ HENRIQUE , BENCHIMOL MARLENE
Published: July 2005

ABSTRACT. Tritrichomonas foetus and Trichomonas vaginalis are protists that undergo closed mitosis: the nuclear envelope remains intact and the spindle remains extranuclear. Here we show, in disagreement with previous studies, that the axostyle does not disappear during mitosis but rather actively participates in it. We document the main structural modifications of the cell during its cell cycle using video enhanced microscopy and computer animation, bright field light microscopy, confocal laser scanning microscopy, and scanning and transmission electron microscopy. We propose six phases in the trichomonad's cell cycle: an orthodox interphase, a pre‐mitotic phase, and four stages during the cell division process. We report that in T. foetus and T. vaginalis: a) all skeletal structures such as the costa, pelta‐axostyle system, basal bodies, flagella, and associated filaments of the mastigont system are duplicated in a pre‐mitotic phase; b) the axostyle does not disappear during mitosis, otherwise playing a fundamental role in this process; c) axostyles participate in the changes in the cell shape, contortion of the anterior region of the cell, and karyokinesis; d) flagella are not under assembly during mitosis, as previously stated by others, but completely formed before it; and e) cytokinesis is powered in part by cell locomotion.
Nuclear Death in Living Tetrahymena: The Case of the Haploid Nuclei
Authors: SANTOS MARIE LOUISE , LU EMILY , WOLFE JASON
Published: July 2005

ABSTRACT. During sexual conjugation in Tetrahymena the micronucleus divides meiotically, producing four haploid nuclei. While one of these nuclei divides mitotically to yield two genetically identical gametic pronuclei, a stationary pronucleus and a migratory pronucleus, the remaining three haploid nuclei degenerate and disappear. Typically, they migrate to the posterior end of the cell where they remain as residual bodies until they disappear. In the present study we asked whether degenerating haploid nuclei share any properties with apoptotic nuclei. Specifically, we wondered whether they would be stained by “apofluor”, a combination of vital fluorescent indicators that differentially stains apoptotic nuclei in living cells. “Apofluor” includes acridine orange, which becomes trapped in acidic compartments and stains lysosomal bodies a brilliant orange‐red, and Hoechst 33342, which binds to DNA and stains nuclei bright blue. With this dye combination, while ordinary nuclei stain blue, the apoptotic macronucleus stains first blue‐green, then yellow, and finally orange. The progression in color is presumed to be due to the accumulation of protons in the apoptotic nucleus compartment. We found that three of the four post‐meiotic haploid nuclei, those that are eliminated, were stained differentially green, then yellow, and then come to be indistinguishable from the orange lysosomal bodies. Differential staining can occur even while the nuclei are located at the anterior ends of the cells, and before the “viable” nucleus divides to form pronuclei. These results indicate that haploid nuclei in the process of degradation are differentially stained in living cells by “apofluor”, and that the differential staining occurs early in the elimination process. Further, since the degenerating haploid nuclei are stained by “apofluor” it is likely that they are degraded by a mechanism similar to the elimination of the apoptotic macronucleus.
Infection of Gymnodinium sanguineum by the Dinoflagellate Amoebophryasp.: Effect of Nutrient Environment on Parasite Generation Time, Reproduction, and Infectivity
Authors: YIH WONHO , COATS D. WAYNE
Published: July 2005

ABSTRACT. Preliminary attempts to culture Amoebophrya sp., a parasite of Gymnodinium sanguineum from Chesapeake Bay, indicated that success may be influenced by water quality. To explore that possibility, we determined development time, reproductive output, and infectivity of progeny (i.e. dinospores) for Amoebophrya sp. maintained on G. sanguineum grown in four different culture media.The duration of the parasite's intracellular growth phase showed no significant difference among treatments; however, the time requiredfor completion of multiple parasite generations did, with elapsed time to the middle of the third generation being shorter in nutrient‐repletemedia. Parasites of hosts grown in nutrient‐replete medium also produced three to four times more dinospores than those infectinghosts under low‐nutrient conditions, with mean values of 380 and 130 dinospores/host, respectively. Dinospore production relative tohost biovolume also differed, with peak values of 7.4 per 1,000 μm3 host for nutrient‐replete medium and 4.8 per 1,000 μm3 host fornutrient‐limited medium. Furthermore, dinospores produced by “high‐nutrient” parasites had a higher success rate than those formedby “low‐nutrient” parasites. Results suggest that Amoebophrya sp. is well adapted to exploit G. sanguineum populations in nutrient‐enrichedenvironments.
Responses of Entamoeba invadens to Heat Shock and Encystation are Related
Authors: FIELD JESSICA , VAN DELLEN KATRINA , GHOSH SUDIP K. , SAMUELSON JOHN
Published: July 2005

ABSTRACT. An Entamoeba invadens gene encoding a homologue of BiP/GRP78, a 70‐kDa heat shock protein or chaperonin was cloned. The predicted E. Invadens BiP contained an ATP‐binding site, a substrate‐recognition domain, and a carboxy‐terminal KDEL‐peptide. Messenger RNAs of E. invadens for BiP, for a 70‐kDa heat shock cognate, for a cyst wall glycoprotein (Jacob), and for chitinase were all induced by heat shock and by encystation medium. The presence of Jacob in heat‐shocked amebae was confirmed by confocal microscopy and suggests that heat shock and encystation responses in E. invadens are related.
Epigenetic Mechanisms Affecting Macronuclear Development in Paramecium and Tetrahymena
Authors: PREER JOHN R.
Published: July 2005

ABSTRACT. Epigenetic inheritance includes all non‐Mendelian inheritance, in fact any inheritance that does not arise from base changes. Ciliates, particularly Paramecium and Tetrahymena, undergo epigenetic changes to their macronuclei when they are formed at nuclear reorganization. Once set, however, they are reproduced in a constant fashion, except for allelic segregations, during vegetative fissions in Tetrahymena and certain life cycle changes in both Paramecium and Tetrahymena. This review is meant to be inclusive, discussing all the known cases of epigenetic changes in macronuclei. They involve virtually all traits. We find that these macronuclear changes are subject to a variety of modifications in the way that they are implemented. They constitute a major feature of ciliate genetics, probably because the separation of generative and vegetative functions to micronuclei and macronuclei makes such changes possible.
Infection by Microsporidia Disrupts the Host Cell Cycle
Authors: SCANLON MARY , SHAW ANDREW P. , ZHOU CHENG J. , VISVESVARA GOVINDA S. , LEITCH GORDON J.
Published: July 2005

ABSTRACT. Microsporidia of the genus Encephalitozoon infect mammalian cells and have become a source of morbidity and mortality in immunocompromised humans. Encephalitozoon microsporidia develop and mature within parasitophorous vacuoles, enlarging the vacuole over time until it eventually occupies most of the cytoplasm of the host cell. The ability of the host cell to accommodate such a large burden for several days suggests that the parasite subverts normal host cell processes to ensure optimal environmental conditions for its growth and development. Since this environment would be threatened if cell division of the host cell occurred, we have formulated the hypothesis that infection with Encephalitozoon microsporidia induces an arrest in the cell cycle of the host cell. In support of this hypothesis, we have found that mitotic index and DNA duplication are reduced in infected cells as compared to uninfected cells. The number of host cell nuclei in S phase is increased. The levels of cyclin D1 and the percentage of cells in G1 are reduced; however, the levels of cyclin B1 are elevated even though the percentage of cells in G2/M is decreased. These results suggest that host cells infected with Encephalitozoon microsporidia are blocked at multiple points in the cell cycle.
A Giant Phosphoprotein Localized at the Spongiome Region of Crithidia luciliae thermophila
Authors: BAQUI MUNIRA M. A. , DE MORAES NADIA , MILDER REGINA V. , PUDLES JULIO
Published: July 2005

ABSTRACT. A giant protein with an apparent molecular mass of 2,300‐kDa was identified in the Triton X‐100 soluble fraction of Crithidia luciliae thermophila. Polyclonal antibody raised against this protein reacted by immunoblot analysis with proteins of similar molecular mass in Crithidia fasciculata and Crithidia oncopelti. In addition, the antibody immunoprecipitates the protein either after in vivo phosphorylation with [32P]orthophosphoric acid or after metabolically labeling with [35S]methionine. Indirect immunofluorescence microscopy analysis performed either with fixed or with live parasites showed a single fluorescent spot at the level of the flagellar pocket region. Immunogold electron microscopy of thin sections of the parasite revealed that the antigen is localized at a restricted area of the spongiome, between the contractile vacuole and the flagellar pocket. Furthermore, Triton X‐114 phase separation of whole cell membrane proteins, metabolically labeled with [35S]methionine, demonstrated that the giant protein remains in the aqueous phase. These results indicate that this phosphoprotein behaves as a peripheral membrane protein localized at the spongiome region, suggesting that it might be involved in the osmoregulatory process.
Characterization of an Unidentified Sarcocystis falcatula‐like Parasite from the South American Opossum, Didelphis albiventris from Brazil
Authors: DUBEY J. P. , LINDSAY D. S. , REZENDE P. C. B. , COSTA A. J.
Published: July 2005

ABSTRACT. An unidentified isolate of a Sarcocystis falcatula‐like parasite was obtained from the lungs of budgerigars (Melopsittacus undulatus) fed sporocysts from a naturally‐infected South American opossum, Didelphis albiventris from Brazil. Four captive budgerigars fed sporocysts from the opossum intestine died of acute sarcocystosis 8, 10, and 12 days after oral inoculation (DAI); one budgerigar was killed 12 DAI when it was lethargic. Schizonts and merozoites found in the lungs of the budgerigars reacted mildly with polyclonal S. falcatula antibody. The parasite was isolated in equine kidney cell cultures inoculated with lung tissue from a budgerigar that was killed 12 DAI. Two budgerigars inoculated subcutaneously with 100,000 culture‐derived S. falcatula merozoites developed acute sarcocystosis and S. falcatula‐like schizonts were found in their lungs 15 and 16 DAI. Four budgerigars kept as unfed controls in the same environment remained free of Sarcocystis infection. The parasite underwent schizogony in African green monkey kidney cells and bovine turbinate cells. Merozoites divided by endopolygeny, often leaving a residual body. Polymerase chain reaction studies using primers JNB33/JNB54 and Hinf I and Dra I digestion indicated that the isolate was not S. falcatula. Results of this study indicated that the South American opossum, D. albiventris, is a definitive host for yet another S. falcatula‐like parasite.
Multi‐Site DNA Polymorphism Analyses of Leishmania Isolates Define their Genotypes Predicting Clinical Epidemiology of Leishmaniasis in a Specific Region
Authors: AKMAN LEYLA , AKSU H. S. Z. , WANG R.‐Q. , OZENSOY S. , OZBEL Y. , ALKAN Z. , OZCEL M. A. , CULHA G. , OZCAN K. , UZUN S. , MEMISOGLU H. R. , CHANG KWANG‐POO
Published: July 2005

ABSTRACT. Leishmania isolates from 57 cases of human cutaneous (CL), human visceral (VL), and canine visceral (CVL) leishmaniasis in Turkey were grouped by multi‐site DNA polymorphism analyses into five genotypes. The initial grouping was based on DNA heterogeneity of the faster‐evolving mitochondrion (kinetoplast) minicircles and the intergenic regions of two nuclear repetitive genes. Taxonomic affiliation and phylogenetic relationships of the five genotypes were inferred by comparing them with reference species for sequence heterogeneity in a ∼1.4 kb conserved single‐copy gene, encoding N‐acetylglucosamine‐1‐phosphate transferase (NAGT). Alignment.of the available sequences revealed no gap, but up to 7% scattered base substitutions, suggesting that this functionally important gene is a suitable marker. Three genotypes are completely identical to the NAGTs of the reference species, identifying them as L. infantum, L. tropica, and L. major, respectively. The remaining two are recognized as L. major NAGT variants with one and four base substitutions, respectively. As expected, Maximum Likelihood analysis of the NAGT sequences separates them into three clades, corresponding to the three species. The majority of the isolates obtained are L. infantum and L. tropica, which have been known to cause infantile VL and anthroponotic CL in western and southeastern Turkey, respectively. Unexpected is the finding of Leishmania major variants and their dispersal, possibly as previously unrecognized clinico‐epidemiologic entities of CL and VL.
mRNA Encoding a Putative RNA Helicase of the DEAD‐Box Gene Family is Up‐Regulated in Trypomastigotes of Trypanosoma cruzi
Authors: DÍAZ AÑEL ALBERTO M. , ROSSI MARIA S. , ESPINOSA JOAQUÍN M. , GÜIDA CATALINA , FREITAS FERNANDO A. , KORNBLIHTT ALBERTO R. , ZINGALES BIANCA , FLAWIÁ MIRTHA M. , TORRES HÉCTOR N.
Published: July 2005

ABSTRACT. Differential display of mRNAs from Trypanosoma cruzi epimastigote and metacyclic trypomastigote stages showed several mRNA species differing in their expression level. The cDNA corresponding to one of these mRNAs was used as a probe in Northern blots and identified a RNA product of 2.6 kb with an expression level eight or more times higher in trypomastigotes than in epimastigotes. This probe was also used to screen a genomic library of T. cruzi CL Brener clone prepared in lambda FIX. A clone of about 15 kb was selected that, after partial sequencing, revealed an open reading frame of 688 amino acids encoding a deduced protein with similarity to RNA helicases of the DEAD‐box gene family. The presence of the eight conserved motifs characteristic of the DEAD protein family was observed in the T. cruzi sequence, indicating that it corresponds to a putative RNA helicase gene, which we named HelTc. Southern blot analysis indicated that HelTc is a single‐copy gene. Pulsed‐field gel electrophoresis separation of chromosomes of several isolates of T. cruzi showed that this gene was localized in one or two chromosomal bands.
MYO1, a Novel, Unconventional Myosin Gene Affects Endocytosis and Macronuclear Elongation inTetrahymena thermophila
Authors: WILLIAMS SELWYN A. , HOSEIN ROLAND E. , GARCÉS JORGE A. , GAVIN R. H.
Published: July 2005

ABSTRACT.Targeted gene disruption was used to investigate the function ofMYO1, an unconventional myosin gene inTetrahymena thermophila.Phenotypic analysis of a transformed strain that lacked a functionalMYO1gene was conducted at both 20°C and 35°C. At either temperature the ΔMYO1strain had a smaller cytoplasm/nucleus ratio than wild type. At 20°C, ΔMYO1populations had a longer doubling time than wild type, lower saturation density, and a reduced rate of food vacuole formation. However, at 35°C, these characteristics were comparable to wild type. Although micronuclear division and cytokinesis appeared normal in ΔMYO1cells, failure of the macro‐nucleus to elongate properly resulted in unequal segregation of macronuclear DNA in cells maintained at either 20°C or 35°C.
5S Ribosomal RNA Gene Repeat Sequences Define at Least Eight Groups of Plant Trypanosomatids (Phytomonas spp.): Phloem‐Restricted Pathogens Form a Distinct Section
Authors: DOLLET MICHEL , STURM NANCY R. , SÁNCHEZ‐MORENO MANUEL , CAMPBELL DAVID A.
Published: July 2005

ABSTRACT. Trypanosomatids isolated from plants have been assigned typically into the genus Phytomonas. Such designations do not reflect the biology of the diverse isolates; confusion may arise due to the transient presence in plants of monogenetic (insect) trypanosomatids deposited by phytophagous bugs. To develop further molecular markers for the plant kinetoplastids, we have obtained the DNA sequence of the 5S ribosomal RNA gene from 24 isolates harvested from phloem, latex, and fruit. Small, distinct sequence differences were found at the 3′‐ends of the transcribed regions; substantial sequence and size differences were found in the non‐transcribed regions. Alignment of the gene sequences from all the isolates suggested the presence of eight groupings. While six groups contained isolates from single plant tissues, groups C and A contained isolates from both fruit and latex. The DNA sequences of the 10 phloem‐restricted pathogenic isolates from South America and the Carribean were highly conserved and thus comprised a single group (H). The conserved nature of the 5S ribosomal RNA genes in these plant pathogens supports the proposal that they be considered as a distinct section, the phloemicola.
Life Cycle and Description of Amblyospora camposi n. sp. (Microsporidia: Amblyosporidae) in the Mosquito Culex renatoi (Diptera, Culicidae) and the Copepod Paracy clops fimbriatus fimbriatus (Copepoda, Cyclopidae)
Authors: MICIELI MARIA V. , GARCIA JUAN J. , BECNEL JAMES J.
Published: July 2005

ABSTRACT. The life cycle of Amblyospora camposi n. sp. is described from the mosquito Culex renatoi and the copepod Paracyclops fimbriatus fimbriatus collected in the leaf axils of the plant Eryngium cabrerae in Argentina. Meiospores of A. camposi (5.8 ± 4.1 μm) were infectious per os to female adults of the copepod P. f. fimbriatus. All developmental stages in the copepod had unpaired nuclei, with sporulation involving the formation of a sub‐persistent, sporontogenic, interfacial envelope and the production of a second type of uninucleate spore. These spores, formed in the ovaries of P. f. fimbriatus, were large, pyriform, and measured 10.70 ± 3.85 μm. When ingested they infected C. renatoi larvae to initiate a sequence that involves schizogony and gametogony and ends with plasmogamy and nuclear association to form diplokaryotic meronts. Oblong ovate binucleate spores (7.86 ± 2.96 μm) are formed in the adult mosquito and are responsible for vertical transmission to the filial generation. This is the first report of an Amblyospora species from a mosquito that inhabits the small‐water bodies held in parts of terresterial plants (phytotelmata).
The SSU rDNA Coding Region of a Filose Amoeba Contains a Group I Intron Lacking the Universally Conserved G at the 3′‐Terminus1
Authors: BHATTACHARYA DEBASHISH , OLIVEIRA MARIANA C.
Published: July 2005

ABSTRACT. We sequenced small subunit ribosomal DNA (rDNA) PCR‐fragments of sizes 2.3 kb and 2.9 kb isolated from a culture of the red alga, Porphyru spiralis var. spiralis. Phylogenetic analysis of the 2.3‐kb fragment showed that it encoded the sequence of a contaminant filose amoeba. The Nuclearia‐like amoeba (named strain N‐Por) was identified with scanning electron microscopy. Its rDNA sequence was positioned with strong bootstrap support within a diverse protist assemblage that includes filose amoebae, chlor‐arachniophytes, cercomonads, and Plasmodiophora brussicae. The rDNA of N‐Por contained a group I intron at the conserved 943 position that remarkably, had a U at the 3′‐terminus rather than the universally conserved G.
The Role of Cortical Geometry in the Nuclear Development of Tetrahymena thermophila
Authors: GAERTIG JACEK , COLE ERIC S.
Published: July 2005

ABSTRACT. Vegetative cells were subjected to electrofusion and the resulting heteropolar doublets were then mated to normal single cells and followed throughout conjugation using cytological and genetic techniques. The unique cytogeometry created in a heteropolar doublet–a continuous cytoplasmic compartment bounded by two anterior poles and sharing a fused posterior pole at midbody, and the potential for two conjugal exchange junctions–resulted in instructive perturbations of nuclear behavior. Our results indicate that the course of nuclear development is strongly dependent on the cortical geometry of conjugating cells. Specifically, 1) continuation of development after meiosis requires an established conjugal junction; 2) after pronuclear exchange, pronuclei are subjected to attractive forces; and 3) products of the second postzygotic division are actively positioned near the posterior region of the cell cortex where they develop into micronuclei.
Recent Advances in Our Knowledge of the Myxozoa
Authors: KENT MICHAEL L. , ANDREE KARL B. , BARTHOLOMEW JERRI L. , EL‐MATBOULI MANSOUR , DESSER SHERWIN S. , DEVLIN ROBERT H. , FEIST STEPHEN W. , HEDRICK RONALD P. , HOFFMANN RUDOLF W. , KHATTRA JASWINDER , HALLETT SASCHA L. , LESTER ROBERT J. G. , LONGSHAW MATTHEW , PALENZEULA OSWALDO , SIDDALL MARK E. , XIAO CHONGXIE
Published: July 2005

ABSTRACT. In the last few years two factors have helped to significantly advance our understanding of the Myxozoa. First, the phenomenal increase in fin fish aquaculture in the 1990s has lead to the increased importance of these parasites; in turn this has lead to intensified research efforts, which have increased knowledge of the development, diagnosis, and pathogenesis of myxozoans. The hallmark discovery in the 1980s that the life cycle of Myxobolus cerebralis requires development of an actinosporean stage in the oligochaete, Tubifex tubifex, led to the elucidation of the life cycles of several other myxozoans. Also, the life cycle and taxonomy of the enigmatic PKX myxozoan has been resolved: it is the alternate stage of the unusual myxozoan, Tetracapsula bryosahnonae, from bryozoans. The 18S rDNA gene of many species has been sequenced, and here we add 22 new sequences to the data set. Phylogenetic analyses using all these sequences indicate that:l) the Myxozoa are closely related to Cnidaria (also supported by morphological data); 2) marine taxa at the genus level branch separately from genera that usually infect freshwater fishes; 3) taxa cluster more by development and tissue location than by spore morphology; 4) the tetracapsulids branched off early in myxozoan evolution, perhaps reflected by their having bryozoan, rather than annelid hosts; 5) the morphology of actinosporeans offers little information for determining their myxosporean counterparts (assuming that they exist); and 6) the marine actinosporeans from Australia appear to form a clade within the platysporinid myxosporeans. Ribosomal DNA sequences have also enabled development of diagnostic tests for myxozoans. PCR and in situ hybridisation tests based on rDNA sequences have been developed for Myxobolus cerebralis, Ceratomyxa shasta, Kudoa spp., and Tetracapsula bryosalmonae (PKX). Lectin‐based and antibody tests have also been developed for certain myxozoans, such as PKX and C. shasta. We also review important diseases caused by myxozoans, which are emerging or re‐emerging. Epizootics of whirling disease in wild rainbow trout (Oncorhynchus mykiss) have recently been reported throughout the Rocky Mountain states of the USA. With a dramatic increase in aquaculture of fishes using marine netpens, several marine myxozoans have been recognized or elevated in status as pathological agents. Kudoa thyrsites infections have caused severe post‐harvest myoliquefaction in pen‐reared Atlantic salmon (Salmo salar), and Ceratomyxa spp., Sphaerospora spp., and Myxidium leei cause disease in pen‐reared sea bass (Dicentrarchus labrax) and sea bream species (family Sparidae) in Mediterranean countries.
Confusing Selective Feeding with Differential Digestion in Bacterivorous Nanoflagellates
Authors: BOENIGK JENS , MATZ CARSTEN , JÜRGENS KLAUS , ARNDT HARTMUT
Published: July 2005

Food selectivity and the mechanisms of food selection were analyzed by video microscopy for three species (Spumella, Ochromonas, Cafeteria) of interception‐feeding heterotrophic nanoflagellates. The fate of individual prey particles, either live bacteria and/or inert particles, was recorded during the different stages of the particle‐flagellate‐interaction, which included capture, ingestion, digestion, and egestion. The experiments revealed species‐specific differences and new insights into the underlying mechanisms of particle selection by bacterivorous flagellates. When beads and bacteria were offered simultaneously, both particles were ingested unselectively at similar rates. However, the chrysomonads Spumella and Ochromonas egested the inert beads after a vacuole passage time of only 2–3 min, which resulted in an increasing proportion of bacteria in the food vacuoles. Vacuole passage time for starved flagellates was significantly longer compared to that of exponential‐phase flagellates for Spumella and Ochromonas. The bicosoecid Cafeteria stored all ingested particles, beads as well as bacteria, in food vacuoles for more then 30 min. Therefore “selective digestion” is one main mechanism responsible for differential processing of prey particles. This selection mechanism may explain some discrepancies of former experiments using inert particles as bacterial surrogates for measuring bacterivory.