bluuebunny/crossref_metadata_2025 huggingface dataset:
A Nuclear‐Envelope‐Specific Protein In Amoeba Proteus Detected With A Monoclonal Antibody
Authors: CHOI EUI Y. , JEON KWANG W.
Published: May 2007

ABSTRACT A protein with two subtypes of 205 and 180 kDa was localized on the nuclear envelope of amoebae as detected by indirect immunofluorescence staining and immuno‐electron microscopy using a monoclonal antibody as a probe. Electron microscopic observation showed that the protein was located on the honeycomb lamina of the nuclear envelope. During mitosis, the protein dispersed throughout the cytoplasm but reappeared on the nuclear envelope after the reformation of the envelopes of daughter nuclei. the findings suggested that the protein is a component of the nuclear lamina of amoebae.
A Soluble Phospholipase of Toxoplasma gondii Associated with Host Cell Penetration
Authors: SAFFER LINDA D. , SCHWARTZMAN JOSEPH D.
Published: May 2007

We previously reported that phospholipase increases host cell penetration by Toxoplasma gondii. Here we show that calcium‐dependent phospholipase A (PLA) activity is found in the supernatant of sonically disrupted T. gondii. When fractions of disrupted T. gondii were incubated with host cells, the release of fatty acids and lysolipids was detected. Fractions of sonically disrupted T. gondii with PLA activity increased T. gondii host cell penetration in a bioassay. In addition, a protein of approximately 20 kDa was detected by immunoblot of T. gondii antigens with horse antiserum to snake venom, the major antibody of which recognizes PLA2. Incubation of T. gondii with exogenous PLA2 resulted in increased solubility of a rhoptry protein. This protein, which we previously characterized as involved with enhanced parasite invasion of host cells and which is recognized by monoclonal antibody Tg49, was detected in increased amounts in supernatant fractions of extracellular parasites treated with PLA2. Whereas without PLA2 treatment, it is only slightly soluble under physiological conditions. This raises the possibility that PLA may be implicated in the release of rhoptry proteins.
Characterization of the Extracellular Ribonuclease of Tetrahymena pyriformis W
Authors: MCKEE TRUDY , PRESCOTT DAVID J.
Published: May 2007

Several investigations have indicated that Tetrahymena pyriformis secretes ribonuclease activity into culture media. The extracellular ribonuclease from strain W has been purified and partially characterized. The molecular weight was determined by gel filtration to be 26,500. The amino acid composition of the enzyme was compared with those of the three intracellular ribonucleases characterized by Trangas, and substantial differences were demonstrated. The extracellular enzyme hydrolyzed both polyadenylic and polyuridylic acids, indicating lack of absolute base specificity. The hydrolysis of polyadenylic acid followed normal Michaelis‐Menten kinetics, but substrate inhibition occurred at high concentrations of polyuridylic acid. The hydrolysis of polyuridylic acid was competitively inhibited by 2′‐ and 3′‐cytidine, guanine, and uridine nucleotides, and by 2′AMP. No inhibition of the hydrolysis of Torula yeast RNA was detected. The kinetic properties of the extracellular ribonuclease are compared with those of the intracellular enzymes.
Pattern Formation in Mirror‐Image Doublets of the Ciliate Stylonychia pustulata
Authors: YANO JUNJI , SUHAMA MIKIO
Published: May 2007

ABSTRACT. Mirror‐image symmetry doublets of the ciliate Stylonychia pustulata were obtained from the progenies of dividing cells in which cell division was inhibited by heat‐shocks. In two components consisting of the doublet, the left (cell's) component possessed ciliary organelles arranged in almost the same pattern as in normal singlets, while the right one had surface organelles located in a mirror‐image symmetry of those of the left component. In cell division of the doublet, two sets of ciliary primordia that were arranged in a mirror‐image symmetry developed synchronously in both components. In about 80% of oral primordia (OP) of the right components, the arrangement of the membranellar bands became abnormal. In some cases, OP of the right component were occasionally separated into two longitudinal halves, each consisting of normal membranelles and inverted membranelles. A set of primordia of the paroral membranelles and fronto‐ventro‐transverse cirri was rarely derived from the basal bodies of the right half with a band of normal membranelles. As a result, a third component with the ciliary organelles normally arranged emerged on the right side of the original right component. The differentiation of membranelles and segmentation of the primordial streaks into cim proceeded from anterior to posterior. A cytoplasmic bulge with multiple right marginal cirral rows was frequently formed at the right margin of the doublet. The behavior in the separation of third and fourth streaks from a primordial streak of dorsal cirri was not mirror‐image symmetrical in each component.
Does Chloroquine, an Antimalarial Drug, Affect Autophagy in Tetrahymena pyriformis?
Authors: NILSSON JYTTE R.
Published: May 2007

ABSTRACT. The effect of chloroquine (CQ) on autophagy was studied in starved Tetrahymena pyriformis. When a proliferating Tetrahymena culture is transferred to a starvation medium, autophagy commences although cells most advanced in the cell cycle will divide. The drug was added to 1‐h starved cells at different pH values because CQ affects pH dependently. The CQ concentration blocking all cell divisions was determined as the lowest toxic, but sublethal, concentration. Hence, the highest tolerated concentrations at pH 6.8, 7.1, and 7.7 were 1.0, 0.3, and 0.03 mM CQ, respectively. Lower CQ concentrations had a dose‐dependent effect on cell increment and higher concentrations induced cell mortality. Rates of cell motility and decreases in cell volume were affected by the drug, while the capacity for endocytosis was unaffected in low concentrations but affected dose dependently in high concentrations. Light microscopically, all drug‐treated cells contained small refractive bodies, but in toxic concentrations they also contained conspicuously large vacuoles. After 1 h and 4 h in CQ, fine structure analysis showed autophagosomes with electron‐dense material in cells in tolerated concentrations and of enlarged size, but decreased number, in toxic concentrations. The contents of autophagosomes revealed cell organelles in different stages of disintegration. The conclusion is that the drug enhances autophagy in Tetrahymena in a pH‐, dose‐, and time‐dependent manner.
The Species Problem in a Ciliate with a High Multiple Mating Type System, Euplotes crassus
Authors: VALBONESI ALESSANDRO , ORTENZI CLAUDIO , LUPORINI PIERANGELO
Published: May 2007

ABSTRACT. One hundred twenty non‐autogamous wild‐type strains of Euplotes crassus, collected over seven years, mainly from the Mediterranean coasts, were investigated for their mating interactions. The strains were mixed pair‐wise and data from mating reactions were evaluated and organized by means of a specially constructed computer program. The program identified 38 strains with distinctive mating patterns which could be clustered in nine clumps, all of which were connected either directly or indirectly. Thus, all these strains appeared to be components of the same gene pool, even though direct genetic exchange between strains was not possible in every combination. Subsequently, the 38 strains were subjected to cytometric analysis and scored for zymic variations resulting from electrophoretic patterns of five enzyme systems (acid phosphatases, amylases, malic dehydrogenase, malic enzyme, and tetrazolium oxidases) of proved diagnostic value in the identification of Euplotes species. No significant discontinuities correlated with mating patterns was apparent from these analyses. It was concluded that the E. crassus strains analyzed are not properly divided in sibling species and it was consistently suggested to avoid a genetic partitioning of ciliate species endowed with high multiple mating type systems, in which the sets of wild strains brought under investigation with difficulty represent the natural dimensions of the species.
The Abundance of Different Peritrich Ciliates on Stone Surfaces in Contrasting Lowland Streams Throughout the Year
Authors: HARMSWORTH GILLIAN C. , HONTS JERRY E. , DRESS VIRGINIA M.
Published: May 2007

ABSTRACT. Pentrich ciliates attached to small stones from the beds of two streams, one large with hard water, the other small with soft water, were enumerated throughout an annual cycle. Throughout the year, Platycola was the dominant peritrich in both streams, except for a brief period during the spring when Vorticella and Carchesium predominated. Vorticella reached peak levels of 89 ciliates cm2 of stone surface, and up to 102 Platycola per cm2 of stone surface were found. Mean volumes of samples of the main species were calculated, and used to estimate the standing stock biomasses. using a standard value of dry weight per unit volume. Published values of the growth rates of representatives of the main genera were used to estimate production values, which totalled about 6.5 g dry weight of peritrich cytoplasm/m2 of stream bed per annum in the large stream (mean annual density = 8.3 peritrichs/cm2 of stone surface), and 33 g dry weight/m2 of stream bed per annum in the small stream (mean annual density = 47 peritrichs/cm2 of stone surface). Food supply, temperature and predation were the primary factors determining peritrich abundance
Morphology and Infraciliature of Three Species of Eutintinnus (Ciliophora; Tintinnina) with Guidelines for Interpreting Protargol‐Stained Tintinnine Ciliates
Authors: CHOI JOONG KI , COATS D. WAYNE , BROWNLEE DAVID C. , SMALL EUGENE B.
Published: May 2007

ABSTRACT. The infraciliatures of three Chesapeake Bay species of Eutintinnus conforming in lorica morphology to E. angustatus, E. pectinis, and E. tenuis were compared following Protargol silver impregnation. The kinetome of these species had a number of shared attributes including: 1) a right and left field that were of similar length and kinetal spacing; 2) two, rarely three, long dorsal kineties composed of monokinetids; 3) a ventral kinety; and 4) the absence of a true posterior kinety. Nonetheless, the specific organization of infraciliary components varied considerably among species. For example, the organization of the ventral kinety and several kineties along the border of the left field was different in all three species. In addition, the dorsal kineties of E. angustatus differed positionally from those of E. pectinis and E. tenuis. Some divergence in oral infraciliature was also noted, with the arrangement of infundibular oral polykinetids in E. pectinis and E. tenuis being distinct from that of E. angustatus. The amount of variation in the infraciliature of Eutintinnus spp. was much greater than previously noted for congeneric species of tintinnines and supports the separation E. angustatus, E. pectinis, and E. tenuis at the generic or subgeneric level.
Morphogenetic Transitions and Cytoskeletal Elements of the Stalked Zooid and the Telotroch Stages in the Peritrich Ciliate Vorticella convallaria
Authors: VACCHIANO EMANUEL , DREISBACH AMY , LOCASCIO DAVE , CASTANEDA LISA , VIVIAN TOM , BUHSE HOWARD E.
Published: May 2007

ABSTRACT. A method is described for obtaining large numbers of telotrochs from mass cultures of Vorticella convallaria. These free‐swimming cells contract slightly along the aboral‐oral plane when extracted with Triton X‐100, and thus appear more similar in shape to zooids than unextracted telotrochs. Cytoskeletal structures associated with feeding, such as the infudibulum and the cytopharynx, are visible in cytoskeletal preparations of these non‐feeding telotrochs and thus appear not to be disassembled during telotroch formation. The telotroch to stalked‐zooid transition proceeds rapidly through a set series of morphogenetic stages. After telotroch attachment, the aboral cilia cease beating and are resorbed. Within 7 min the cell is inverted bell‐shaped and the zooid begins feeding. Stalk elongation begins about 15–20 min after attachment, lengthening at the rate of 0.5 μ/min for the first hour and more slowly (0.1 μm/min) after that. Interestingly, these developmental stages are essentially the same as those described for the telotroch to zooid transition in the colonial peritrich Zoothamnium. This evolutionary conservation suggests that the precise sequence and timing of these events are critical for their successful completion. Furthermore, the facts that the telotroch to zooid transition occurs very rapidly, that the feeding structures are maintained throughout the transformation, and that basic cytoskeletal architecture is relatively unchanged is consistent with the hypothesis that the transformation occurs through controlled cytoskeletal rearrangements rather than by changes in gene expression.
Morphology and Morphogenesis of Strobilidium caudatum (Fromentel), Meseres corlissi N. Sp., Halteria grandinella (Müller), and Strombidium rehwaldi N. Sp., and a Proposed Phylogenetic System for Oligotrich Ciliates (Protozoa, Ciliophora)1
Authors: PETZ WOLFGANG , FOISSNER WILHELM
Published: May 2007

ABSTRACT. The morphology and morphogenesis of some oligotrichs were investigated using protargol impregnation, silver carbonate impregnation and scanning electron microscopy. The somatic kineties of Strobilidium caudatum form a spiral at the posterior pole. Strobilidiids without such a spiral are transferred to the genus Rimostrombidium. Fourteen new combinations and a nomen novum, Strobilidium kahli, are necessary, Meseres corlissi n. sp. is characterized by eight somatic kineties composed of long cilia which are not fused to “bristles” as they are in Halteria. Strombidium oblongum shows similar characteristics and is thus combined with Meseres. Strombidium rehwaldi n. sp. has an anterior and an equatorial girdle of extrusomes. The morphogenesis of Meseres and Halteria is very similar, i.e. the entire somatic ciliature and the oral primordium originate apokinetally on the cell surface; the parental somatic ciliature is resorbed. In strobilidiids and tintinnids, the oral anlagen develop in a subsurface pouch and the parental somatic kineties, which are not resorbed, elongate by intrakinetal proliferation of basal bodies. In strombidiids, the oral primordium develops in an intracellular sac or tube. These morphogenetic peculiarities and distinct morphologic characters (e.g. arrangement of adoral membranelles) were applied in constructing a phylogenetic system for oligotrichs using hypotrichs as outgroup. This shows that halteriids are more closely related to hypotrichs than they are to other oligotrichs. The Halteriidae are thus raised to ordinal and subclass ranks, Halteriida n. ord., Halteriia n. subcl.
Macromolecules Involved in the Amoeba‐Bacteria Symbiosis1
Authors: JEON KWANG W.
Published: May 2007

ABSTRACT. In the Amoeba‐bacteria symbiosis, rod‐shaped Gram‐negative bacterial endosymbionts reside within symbiosomes in the host cytoplasm, and the host and symbionts are mutually dependent for survival. Three proteins and one group of lipopolysaccharides (LPS) synthesized by the bacterial endosymbionts and two proteins derived from the host cells have been found to be involved in the host‐symbiont interactions, although their respective roles are not yet fully known. The symbiont‐derived molecules included proteins with molecular weights of 29 kDa, 67 kDa and 96 kDa and LPS. The 29‐kDa protein was most abundant in the host cytoplasm, while the 96‐kDa protein and LPS were found mostly on the symbiosome membranes. The 67‐kDa protein was a GroEL analog and stayed within the symbionts. The host‐derived 43‐kDa protein, actin, was selectively accumulated by the symbionts, while the 220/225‐kDa protein, spectrin, was attached to the symbiosome membranes. The symbiont genes coding for the 29‐kDa and 67‐kDa proteins were cloned and sequenced. The 29‐kDa protein gene was unique with no relation to any known DNA sequences but has a leucine zipper‐like motif, suggesting a possible DNA‐binding function. The DNA sequence of the 67‐kDa protein gene showed a 70% identity with heat‐shock‐protein genes of Escherichia coli and Coxiella burnetii.
Cell Surface Interactions between Trypanosoma congolense and Macrophages during Phagocytosis In Vitro
Authors: SHAKIBAEI MEHDI , FREVERT UTE
Published: May 2007

ABSTRACT. Trypanosoma congolense bloodstream forms preincubated with a high titer of anti‐variant surface antigen (VSG)‐specific antibody, a low amount of anti‐VSG plus complement‐active mouse serum (MS), MS alone, and trypsin were cocultivated with mouse peritoneal macrophages in vitro. Immunofluorescence as well as transmission and scanning electron microscopy revealed that upon attachment to the macrophages' surface, trypanosomes opsonized with anti‐VSG/MS formed opsonized filopodia, which were rapidly internalized by the phagocytes. Although these cells attached as frequently as anti‐VSG or trypsin‐pretreated parasites, the rate of phagocytosis of anti‐VSG/MS pretreated trypanosomes was reduced significantly. Trypanosomes pretreated with high antibody titers alone were lysed on the surface of the macrophages before phagocytosis was completed. Parasites opsonized with complement alone adhered only occasionally and were rarely phagocytosed. Trypsin‐treated trypanosomes, which served as positive control cells, rapidly attached and remained intact until ingulfment by the macrophages was completed. Untreated control parasites did not attach to the macrophages and were not phagocytosed. Cocultivation of macrophages with anti‐VSG/MS‐opsonized trypanosomes caused internalization of the flagellum by membrane fusion. Filopodia formation by T. congolense is thus correlated with a marked reduction in phagocytosis even in the presence of only a sublytic antibody titer.
Cell Surface Saccharides in Three Phytomonas Species Differing in Host Specificity
Authors: NAKAMURA CELSO VATARU , ESTEVES MANUEL JOSE GIL , ANDRADE ARNALDO FEITOSA BRAGA , ALVIANO CELUTA SALES , DE SOUZA WANDERLEY , ANGLUSTER JAYME
Published: May 2007

ABSTRACT. Cell surface carbohydrates of three phytoflagellates, Phytomonas francai. Phytomonas serpens and Phytomonas sp. from different hosts including cassava, coreid insect Phthia picta and the milkweed plant Euphorbia hyssopifolia, respectively, were analysed by agglutination assays employing a battery of highly purified lectins with affinity for receptor molecules containing N‐acetylglucosamine (d‐GlcNAc), N‐acetylgalactosamine (D‐GalNAc), galactose, mannose‐like (D‐Man‐like) residues and fucose, and by binding assay using radiolabeled [125I]‐wheat germ agglutinin (WGA) and fluorescent WGA lectin, as well as glycosidases of known sugar specificity, Escherichia coli K with mannose‐affinity fimbrial lectin was also used as an agglutination probe. In general, the presence of D‐GlcNAc. D‐GalNAc and D‐Man‐like residues was detected in the phytomonads' plasma membrane. These sugar moieties were confirmed in whole cell hydrolysates as assessed by gas‐liquid chromatography (GLC) which in addition, also showed the presence of galactose and xylose. However, marked differences in cell surface carbohydrate structures were observed. Wheat germ agglutinin, which binds to sialic acid and/or d‐GlcNAc‐containing residues, shows selective agglutinin activities for P. francai and Phytomonas sp., while Bandeiraea simplicifolia II agglutinin (which recognizes d‐GlcNAc units) specifically bound to Phytomonas sp. Helix pomatia agglutinin which binds to D‐GalNAc‐containing residues reacted preferentially with Phytomonas sp. and P. serpens. Con A, which recognizes D‐Man‐like receptors, agglutinates all the phytomonads; however, the higher interaction was observed with Phytomonas sp. P. francai was selectively agglutinated in the presence of E. coli fimbrial lectin. Fluorescence WGA binding was significantly decreased by N‐acetylglucosaminidase activities and the cell agglutination was not altered by neuraminidase treatment, suggesting the presence of an exposed D‐GlcNAc moiety on the P. francai and Phytomonas sp. surfaces. Binding studies with [125I]‐WGA essentially confirmed the fluorescence WGA binding and agglutination assays.
Development of Plasmodium berghei Ookinetes to Young Oocysts In Vitro
Authors: SYAFRUDDIN  , ARAKAWA RYO , KAMIMURA KIYOSHI , KAWAMOTO FUMIHIKO
Published: May 2007

ABSTRACT. The mosquito stage of Plasmodium berghei was cultivated in vitro, with special attention to ookinete transformation into early oocyst. The ookinetes were obtained by in vitro culture of gametocytes taken from infected mice, purified by density gradient of metrizoic acid or a lymphocyte separation medium, and incubated either in acellular culture or in co‐cultivations with mosquito cells. In acellular culture, the ookinetes were found to aggregate with each other and transformed from banana to round shapes. Their inner pellicular membranes and subpellicular microtubules partially disappeared, indicating that development to early oocyst had occurred. Co‐cultivation with Aedes albopictus cells (C6/36 clone) revealed that ookinetes transformed into early oocyst in the medium, or invaded the cells and then transformed to early oocysts within the cell cytoplasm as well. However, all of these transformed cells failed to develop further, i.e. neither deposition of the oocyst capsule nor nuclear division was observed. Many ookinetes which failed to penetrate the Aedes cells were phagocytized within three days of culture. A significant difference between invaded and transformed oocysts and phagocytized ookinetes was seen in that the former lacked vacuole membrane. Co‐cultivation with Toxorhynchites amboinensis cells (TRA‐284‐SFG clone) permitted transformation of ookinetes into early oocysts in the medium as in the acellular culture, but no ookinete invasion nor phagocytosis by the cell was observed.
Identification of Acanthamoeba at the Generic and Specific Levels Using the Polymerase Chain Reaction
Authors: VODKIN MICHAEL H. , HOWE DANIEL K. , VISVESVARA GOVINDA S. , McLAUGHLIN GERALD L.
Published: May 2007

ABSTRACT. We have adapted the polymerase chain reaction to identify strains of Acanthamoeba. Using computer‐assisted analysis, primers were designed from an anonymous repetitive sequence and from published sequences of 18S and 5S ribosomal RNA genes of A. castellanii. Amplification of a short ribosomal DNA target (272 base pairs) at restrictive annealing conditions (>50° C) resulted in a single band that was unique for the genus and distinguished Acanthamoeba from Naegleria. This assay functioned with fresh and formalin‐fixed cells as starting material. Amplification of longer targets (400–700 base pairs) at less restrictive annealing conditions (<47° C) led to more than one band. This multiple banding pattern could reproducibly classify Acanthamoeba at the strain level and was, in certain cases, diagnostic for known pathogenic strains. However, these assays need to be further refined to make them relevant for clinical purposes.
An Ultrastructural Study of Vairimorpha necatrix (Microspora, Microsporida) with Particular Reference to Episporontal Inclusions During Octosporogony
Authors: MOORE CLYDE B. , BROOKS WAYNE M.
Published: May 2007

ABSTRACT. The life cycle of Vairimorpha necatrix was studied by electron microscopy. Disporous development has two distinct stages: 1) diplokaryotic meronts which are actively mitotic, and 2) diplokaryotic sporonts which are distinguished by reduced ribosome density and a thickened plasmalemma. After final division of the sporont, sporoblasts form spores which are ovocylindrical and measure 4.4 ± 0.08 × 2.3 ± 0.05 μm (mean ± SE). Octosporous development results in eight haploid spores being formed in a sporophorous vesicle. The uninucleate octospores were smaller than the binucleate dispores and the exospore was thicker but less crenulate in outline. Early in octosporogony, tubules are produced from the sporont plasmalemma and electron‐dense material accumulates in the episporontal space. The latter may be amorphous, vesiculated, or vacuolated in appearance and in later stages may take a stacked, lamellar form. At sporoblast formation, exospore material coats the plasmalemma and attached tubules; all inclusions in the episporontal space gradually disappear as spores are formed. These secretory products may have application to taxonomic distinction at the species level.
Evidence of Tyrosine Kinase Activity in the Protozoan Parasite Trypanosoma brucei
Authors: WHEELER‐ALM ELIZABETH , SHAPIRO STUART Z.
Published: May 2007

ABSTRACT. Phosphorylation of proteins at tyrosine is an important mechanism for regulating cell growth and proliferation in metazoan organisms. In this report, we have demonstrated that Trypanosoma brucei, a protozoan parasite, possesses a tyrosine kinase that plays a role in regulation of proliferation of this protozoan. Genistein, a tyrosine kinase inhibitor, prevented multiplication of the parasite. An in vitro kinase assay demonstrated the presence of a kinase capable of phosphorylating an exogenous substrate at tyrosine, and genistein was able to reduce trypanosome‐mediated phosphorylation of this substrate. An alkali digestion of 32P‐labeled trypanosome proteins separated by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis indicated several proteins phosphorylated at tyrosine. These results indicate that T. brucei has a tyrosine kinase that is involved in proliferation or growth regulation of the parasite and provide further evidence for the possibility of growth factor regulation and signal transduction in trypanosomes.
Enhanced Gametocyte Formation in Young Erythrocytes by Plasmodium falciparum In Vitro
Authors: TRAGER WILLIAM , GILL GOKAL S.
Published: May 2007

ABSTRACT. Two gametocyte‐forming clones, HB‐3 and 3D7, were used. Concentrates of late stage parasites were mixed with bloods containing different proportions of young erythrocytes, and the parasitemia and proportion of gametocytes determined after 2, 3 or 4 days of culture. Significantly more gametocytes were formed in light cells than in heavy cells separated from the same normal blood samples. Up to seven times more gametocytes were formed in reticulocyte‐rich bloods from patients with sickle cell anemia than in normal control blood.
An Assessment of Proteolytic Enzymes in Tetrahymena thermophila
Authors: STRAUS J. WILLIAM , MIGAKI GRACE , FINCH MARIA T.
Published: May 2007

Cellular extracts of Tetrahymena thermophila were found to contain substantial levels of proteolytic activity. Protein digestion occurred over broad ranges of pH, ionic strength, and temperature and was stimulated by treatment with thiol reductants, EDTA and sodium dodecyl sulfate. Incubation at temperatures ≥60° C or with high concentrations of chaotropic reagents such as 10 M urea or 6 M guanidine‐HCl caused an apparent irreversible loss of activity. Activity was also strongly diminished by increasing concentrations of divalent cations. Several peptide aldehydes, p‐hydroxymercuribenzoate, and alkylating reagents such as iodoacetate, N‐tosyl‐L‐lysine chloromethyl ketone, N‐tosyl‐L‐phenylalanine chloromethyl ketone, N‐methylmaleimide, and trans‐epoxysuccinyl‐L‐leucylamido‐(4‐guanidino)‐butane were potent inhibitors of proteolytic activity. Aprotinin diminished activity by approximately 40% while benzamidine, 3,4‐dichloroisocoumarin, and trypsin inhibitors from soy bean, lima bean, and chicken egg caused relatively modest inhibition of proteolytic activity. Phenylmethanesulfonyl fluoride had no apparent effect. Electrophoretic separation of proteins on SDS‐polyacrylamide gels copolymerized with gelatin substrate revealed that at least eight active proteolytic enzymes were present in cell extracts ranging in apparent molecular weight from 45,000 to 110,000. Five of these apparent proteases were detected in 70% ammonium sulfate precipitates. Gelatinase activity was not detectable when extracts were pretreated with iodoacetate or E‐64, indicating that all of the enzymes observed in activity gels were sensitive to thiol alkylation. Cellular extracts of T. thermophila appeared to contain multiple forms of proteolytic enzymes which were stimulated by thiol reductants and inhibited by thiol modifying reagents. Accordingly, the proteolytic enzymes present in cell extracts appear to be predominantly cysteine proteinases.
Micronuclear DNA from Paramecium tetraurelia: Serotype 51 A Gene Has Internally Eliminated Sequences
Authors: PREER LOUISE B. , HAMILTON GUY , PREER JOHN R.
Published: May 2007

A method for the isolation of micronuclear DNA from Paramecium tetraurelia has been developed. After cell lysis, a low speed centrifugation at 1,000 g is used to remove all of the unbroken cells and macronuclei and approximately two thirds of the macronuclear fragments. Next a higher speed centrifugation of 9,000 g sediments the micronuclei and frees them from small particulates and soluble constituents. Advantage is then taken of the fact that micronuclei have a lower density than do macronuclear fragments in 45%–60% Percoll. Micronuclei float to the top during centrifugation at 24,000 g, while macronuclear fragments sediment. After several cycles of centrifugation in Percoll, the micronuclei, although heavily contaminated with cytoplasmic components, are essentially free of macronuclei and macronuclear fragments. Micronuclear DNA can then be extracted from the suspension. The whole procedure is very rapid and in about an hour micronuclear and macronuclear DNA can be separated. About 2 μg of micronuclear DNA can be obtained from 6 times 107 paramecia. We find that there are internal sequences in the micronuclear A gene DNA in wild type cells which are eliminated when the micronuclei develop into macronuclei. They yield unique restriction fragments for micronuclei and macronuclei. Therefore the purity of the preparations is easily monitored by probing Southern blots of restriction enzyme‐digested DNA with the cloned A gene. No differences have been found between the micronuclear A gene in wild type and the d48 mutant.
Experimental Horizontal Transmission of Enterocytozoon salmonis to Chinook Salmon, Oncorhynchus tshawytscha
Authors: BAXA‐ANTONIO DOLORES , GROFF JOSEPH M. , HEDRICK RONALD P.
Published: May 2007

Enterocytozoon salmonis was transmitted to chinook salmon Oncorhynchus tshawytscha by feeding tissues infected with the parasite and by cohabitation of noninfected fish with experimentally infected fish. Affected fish (dead and survivors) in both transmission trials had gross and microscopic signs of the disease and merogonic and sporogonic stages of the parasite. There were no morbidities or mortalities, or evidence of the parasite among control fish in either study. Results suggest that the parasite may be contracted by indirect contact among healthy and infected fish held in crowded ponds or net pens or by direct ingestion of spores found in the water.
Extracellular Matrix Augments Mechanical Properties of Pseudopodia in the Carnivorous Foraminiferan Astrammina rara: Role in Prey Capture
Authors: BOWSER SAMUEL S. , ALEXANDER STEPHEN P. , STOCKTON WILLIAM L. , DELACA TED E.
Published: May 2007

The seemingly delicate, strand‐like pseudopodia of Astrammina rara, a carnivorous benthic foraminiferan, adhere to and withstand the rigorous movements of meiofaunal prey. Previous electron microscopic studies identified two novel structures that might account for the unusual tensile properties of these pseudopodia: 1) an extensive, coiled microtubule cytoskeleton and 2) a fibrous extracellular matrix vesting the pseudopodial surface. In the present study, we found that pseudopodial networks microsurgically removed from A. rara's cell body captured Artemia metanauplii as efficiently as intact organisms, and therefore used them to test the role of microtubules and extracellular matrix components in augmenting pseudopodial strength. Agents that specifically disassemble micro‐tubules (1 mM colchicine or 20 μM nocodazole) or generally disrupt pseudopodial integrity (heat, 10 mM formaldehyde, 1 mg/ml saponin) failed to inhibit prey capture. All of these treatments left the extracellular matrix intact as revealed by immunofluorescence and scanning electron microscopy. The elastic and tensile properties of the extracellular matrix, isolated by solubilization of pseudopodial cytonhsm using the nonionic detergent Triton X‐100, were similar to those of intact pseudopodial networks when assayed with calibrated microneedles or a flexible rubber substrate. These observations indicate that A. rara uses a fibrous extracellular matrix to augment cytoplasmic tensile properties.
Life Cycle of Goussia pannonica (Molnar, 1989) (Apicomplexa, Eimeriorina), an Extracytoplasmic Coccidium from the White Bream Blicca bjoerkna
Authors: LUKES JULIUS
Published: May 2007

ABSTRACT Life cycle stages of Goussia pannonica from naturally‐infected white bream Blicca bjoerkna were studied by light and electron microscopy. Fourteen of the sixteen fish examined were infected, with developmental stages found in all parts of the intestine. Merogonial, gamogonial, and sporogonial stages were localized intracellularly and extracytoplasmically in the microvillous region of enterocytes. They were separated from the gut lumen by closely apposed enterocyte and parasitophorous vacuole membranes. There were two types of extracytoplasmic attachment: 1) monopodial, with a single zone of attachment, and 2) spider‐like, with several isolated zones of attachment to the host cell. First‐generation merozoites were formed by ectomerogony. Second‐ or third‐generation merozoites were formed by endodyogeny and endopolygeny. Thirty to 50 biflagellated microgametes developed at the periphery of a microgamont. Macrogamonts contained lipid inclusions, amylopectin and dense granules; however, granules comparable to wall‐forming bodies type I and II were absent. At the beginning of sporogony, the sporont cytoplasm detached from two layers which subsequently became constituents of the oocyst wall. After the rupture of enterocyte and parasitophorous vacuole membranes, the sporont was released into the water where exogenous sporulation was completed within 48 h. The thin sporocyst wall contained a small longitudinal suture. Sporocyst and oocyts walls were of similar structure.
Schizogonic Development of Leucocytozoon smithi
Authors: STEELE EDNA JOSEF , NOBLET GAYLE PITTMAN
Published: May 2007

ABSTRACT The schizogonic development of Leucocytozoon smithi in the liver of experimentally infected turkey poults was examined by electron microscopy. Following intraperitoneal injection, sporozoites migrated to the liver and entered hepatic cells to become intracellular trophozoites. Three to four days post inoculation (PI), trophozoites underwent asexual multiple fission known as merogony or schizogony. Two generations of schizonts were observed. The primary or first generation schizonts, abundant on day 4 PI, appeared as interconnected cytoplasmic masses (pseudocytomeres). Each pseudocytomere was enclosed by a membranous vacuole and contained varying numbers of nuclei. As nuclear division and growth of the schizonts continued, larger discrete cytoplasmic masses or cytomeres were formed with rhoptries and multiple nuclei in various stages of division. Synchronous multiple cytoplasmic cleavage of the schizont resulted in the formation of numerous uninucleate merozoites. Second generation schizonts, which developed from hepatic merozoites released from primary schizonts, were abundant in hepatocytes on day 6 PI. Although tissue samples from liver, lung, spleen, kidney, intestine, brain, blood vessels and lymph nodes were examined, schizogonous forms were observed in liver only. No megaloschizonts were detected in any host tissue examined. Schizogonic development was completed by day 7 PI as merozoites developed into gametocytes within mononuclear phagocytes.
Freeze‐Fracture Study of the Site of Attachment of Cryptosporidium muris in Gastric Glands
Authors: YOSHIKAWA HISAO , ISEKI MOTOHIRO
Published: May 2007

ABSTRACT The mode and organization of the attachment site of Cryptosporidium muris to gastric glands of stomach were investigated by the freeze‐fracture method. Cryptosporidium muris was enveloped by a double membrane, of host plasma membrane origin, which formed the parasitophorous vacuole. The outer membrane of the double membrane was continuous with host plasma membrane, while the inner membrane was connected with the anterior part of the parasite plasma membrane at the annular ring. The density of intramembranous particles (IMP) was severely altered at the above two junctures. The parasitophorous outer membrane showed low IMP‐density when compared to the host plasma membrane, although both membranes were continuous at the dense band. The inner membrane had few IMP, whereas the parasite plasma membrane showed numerous IMP, although both membranes were continuous at the annular ring. The size of dense band and annular ring was similar in diameter. The feeder organelle was clearly visible as membrane folds in freeze‐fracture and some of them were connected with small vesicles of cytoplasm, indicating that the feeder organelle may play an important role for incorporation of nutrients from the host cell.
A Chemostat Study on Proline Uptake and Metabolism of Leishmania donovani
Authors: KUILE BENNO H. TER , OPPERDOES FREDERIK R.
Published: May 2007

ABSTRACT Leishmania donovani grew in the chemostat on proline as its sole carbon and energy source at a maximum growth rate of 1.39 divisions per day. The efficiency of proline metabolism decreased with increasing external proline concentration. The internal concentration of proline and its intracellular metabolites was low when proline was the growth rate limiting substrate and high when proline was available in excess. In time‐course experiments proline uptake leveled off after 30 min, independent of the culture conditions prior to the experiment. Proline uptake depended on the external proline concentration in a manner that is best described as the combination of an enzymatic and a diffusion component. Adaptation to different proline concentrations did not occur and no evidence was found that proline is actively transported by L. donovani.
Isoenzyme Comparison of Axenic Giardia lamblia Strains
Authors: MOSS DELYNN M. , VISVESVARA GOVINDA S. , MATHEWS HENRY M. , WARE DORIS A.
Published: May 2007

ABSTRACT We obtained isoenzyme patterns by polyacrylamide gradient gel electrophoresis (PGGE) of water‐soluble protein fractions prepared from trophozoites of 11 axenic G. lamblia strains. The strains were isolated from animals and humans (both symptomatic and asymptomatic) from various geographic locations. Isoenzymes were also separated by isoelectric focusing. Of 12 enzymes attempted, eight exhibited well‐defined and reproducible isoenzyme patterns by PGGE, based on which the strains were grouped into four zymodemes. Although the 11 strains were grouped into four zymodemes based on PGGE, no correlation between zymodeme and the known characteristics of the strains existed. Thus, a high degree of characteristic sharing appears to occur among genetically different G. lamblia strains.
Amphotericin B‐Induced Carbohydrate Changes on the Trypanosoma cruzi Surface Membrane
Authors: HAIDO ROSA M. T. , ESTEVES MANUEL J. G. , BARRETO‐BERGTER ELIANA
Published: May 2007

ABSTRACT Changes in the cell surface carbohydrates of Trypanosoma cruzi epimastigotes induced by Amphotericin B (AmB) were assessed by chemical methods and by agglutination assay employing a panel of highly purified lectins of various sugar specificities, Escherichia coli K12 with mannose‐sensitive fimbriae was also used as an agglutination probe. Amphotericin B caused a decrease in the total carbohydrate content of all glycoconjugate fractions isolated. Exposure to AmB strongly affected the mannose/galactose ratio (1:5) in the CHCI3/methanol/H2O soluble fraction. These sugars in 1.4:1 ratio were the major hexose components of control cells. The decrease in the mannose content (48 to 15%) after AmB treatment agrees with the marked decrease in the T. cruzi cell surface receptors for fimbriated E. coli K12. Also, an increase in the galactose content (74%) as compared with control cells (34%) is in agreement with the peanut agglutinin and Euonymus europaeus lectins agglutination results. Differences in the cell surface carbohydrates induced by AmB could be associated with alterations in the membrane structure and organization.
Inter‐ and Intrasyngenic Variations of the Hemoglobin Components inParamecium caudatum
Authors: HIRAI ITARU , USUKI ITARU , OCHIAI TAKEHIKO
Published: May 2007

ABSTRACTThe ciliated protozoanParameciumcontains hemoglobin in heterogeneous monomeric forms. In particular,Paramecium caudatumis characterized by the presence of a major component called Hb10 and a basic component named bHb. We found that inP. caudatumboth of these hemoglobin components show some variation according to stock. The types and distributions of these hemoglobin components were examined on 16 stocks in five different syngens and one stock in an unidentified syngen using high performance liquid chromatography. The results indicate that in a variety of stocks the major component, Hb10, was divided into three types, A, B or A + B, and that the basic hemoglobin component was composed of a combination of two or three variants out of four possible, i.e. bHb 1, bHb 2, bHb 3 and bHb 4. Neither the Hb10 types nor the bHb variants, however, could be used to distinguish syngen inP. caudatum, since all of the Hb10 types and bHb variants were widely distributed over syngens and identical profiles appeared to some stocks in different syngens.
Unclassified Protists of Arthropods: The Ultrastructure of Nephridiophaga periplanetae (Lutz & Splendore, 1903) N. Comb., and the Affinities of the Nephridiophagidae to Other Protists
Authors: LANGE CARLOS E.
Published: May 2007

Observations by electron microscopy were conducted on Coelosporidium periplanetae (Lutz & Splendore, 1903) Swarczewsky, 1914, an extracellular sporogenic protist in the lumen of the Malpighian tubules of Blatta orientalis Linn., 1758 and other domiciliary cockroaches. Results generally agreed with earlier studies by light microscopy but also allowed a more complete characterization of the species. Some outstanding features of the protist were: amoeboid multinucleate stages (plasmodia) capable of producing cytoplasmic projections for attachment to microvilli of tubules, endogenous formation of spores, differentiation of “generative” and “somatic” nuclei in plasmodia undergoing spore formation, polarized early sporoblasts (a nucleus on one half and a chondriome on the other), and biconcave, ovoid, non‐polarized spores that are retained until maturation by the plasmalemma and residual cytoplasm of the original plasmodium. The new combination Nephridiophaga periplanetae is proposed based on this new, updated information. The family name Nephridiophagidae Sprague, 1970 is resurrected to include N. periplanetae and eleven other species of protists in the Malpighian tubules of arthropods, mostly insects in the orders Dictyoptera and Coleoptera. According to its characteristics, the family Nephridiophagidae cannot be included into any of the currently recognized phyla of protists. It is suggested that it should be temporarily treated as an incertae sedis group of Protista.
Contributions to the Life Cycle of Peneroplis planatus (Fichtel and Moll) Montfort
Authors: FABER WALTER W. , LEE JOHN J.
Published: May 2007

Direct observations of schizonts and agamonts releasing megalospheres clarified the asexual phase of the life cycle of Peneroplis planatus and made it most probable that this species has a paratrimorphic life cycle. Specimens with maximum lengths between 837 and 3,503 μm released about 500 to 1,500 megalospheric juveniles, which possessed two chambers (proloculi and flexostyles) prior to emergence from the parental shell. The presence of gamonts was not shown and was only implied by the occurrence of the agamonts. Since agamonts and schizonts have been found from December to May and since asexual reproduction occurs in spring in Elat, sexual reproduction probably occurs at another time of year (June to December). More detailed studies of this species need to be conducted throughout the year to improve our knowledge of the life cycle of this species.
Starvation Induces Tomitogenesis in Miamiensis avidus Strain Ma/21
Authors: GÓMEZ‐SALADÍN EDUARDO , SMALL EUGENE B.
Published: May 2007

Miamiensis avidus is a marine polymorphic scuticociliate that undergoes microstome to tomite transformation when nutrients are depleted. This transformation takes place as a result of two consecutive divisions and does not involve a cyst. Tomitogenesis was induced by nutrient deprivation. When returned to nutrient medium tomites transformed into microstomes. Changes in population were noted at one‐hour intervals. Tomites of Miamiensis avidus Ma/2 are compared to dispersal stages in other scuticociliates and hymenostomes.
Incorporation of Label from Acetate and Laurate into the Mannan of Leishmania donovani via the Glyoxylate Cycle
Authors: KEEGAN FRANK P. , BLUM J. JOSEPH
Published: May 2007

Leishmania donovani promastigotes in late‐stationary phase incorporated label from [2‐14C]acetate and [1‐14C]laurate into the mannose residues of mannan, thus confirming the presence of a functional glyoxylate bypass in these parasitic protozoa. Isolated, washed calls also incorporated label from [2‐14C]acetate and [1‐14C]laurate into mannan during a 1‐hr incubation in buffer. Glucose had no effect on label incorporation into mannan, but glutamate caused over a four‐fold increase in incorporation from [2‐14C]acetate and a 2.4‐fold increase from [1‐14C]laurate. Staurosporine, a protein kinase inhibitor that inhibits glutamate and alanine oxidation, did not inhibit label incorporation from [2‐14C]acetate into mannan. Hyperosmolality caused about a 33% inhibition of label incorporation into mannan. These results show the glyoxylate cycle and/or the subsequent biosynthetic pathway from fructose‐6‐phosphate to mannan are subject to regulation.
Molecular Genetic Distinction of Pneumocystis carinii from Rats and Humans
Authors: STRINGER JAMES R. , STRINGER SAUNDRA L. , ZHANG JIANXIONG , BAUGHMAN ROBERT , SMULIAN A. GEORGE , CUSHION MELANIE T.
Published: May 2007

Pneumocystis carinii from rats and from humans were compared with respect to electrophoretic karyotype, presence of DNA sequences known to be repeated in rat‐derived P. carinii, overall DNA sequence homology, and the sequences at two genetic loci. The organisms from each host species were different in each respect. Neither of two repeated DNAs from rat‐derived P. carinii was found in the genome of human‐derived organisms, and total DNA from rat‐derived P. carinii failed to hybridize to human‐derived P. carinii DNA. The sequences of the α‐tubulin genes from the two P. carinii were strikingly different and the base composition of the α‐tubulin gene from rat‐derived P. carinii was rich in adenine and thymine, while the base composition of this gene from human‐derived P. carinii was rich in guanine and cytosine. The sequence from the 18S rRNA gene of human‐derived P. carinii was twice as divergent from that of rat‐derived P. carinii as the sequence from the corresponding region of Candida albicans was from that of Candida tropicalis. These data show that rats and humans can harbor distinct types of P. carinii that are sufficiently different to suggest that P. carinii from the two hosts could be different species.