bluuebunny/crossref_metadata_2025 huggingface dataset:
Receptor‐Mediated Endocytosis in the Bloodstream Form of Trypanosoma brucei1
Authors: Coppens I. , Opperdoes F. R. , Courtoy P. J. , Baudhuin P.
Published: May 2007

The uptake of various host plasma proteins by the bloodstream form of Trypanosoma brucei was studied both biochemically, using radiolabeled proteins, and with the electron microscope, using colloidal gold particles as molecular tracers onto which plasma proteins had been adsorbed. Total plasma proteins and serum albumin were taken up by a mechanism of fluid endocytosis with low clearance (0.1 μ1 [mg cell protein]‐1 h‐1), while low‐density lipoprotein (LDL) and transferrin were taken up by a receptor‐mediated process with a clearance of two to three orders of magnitude higher than that of serum albumin. Binding prior to uptake of LDL and transferrin was saturable, depended on the presence of Ca2+, and the labeled ligand could be displaced by the homologous but not by heterologous protein. Binding of gold‐labeled proteins was seen only to the membrane of the flagellar pocket and not elsewhere on the plasma membrane. After 1 h of incubation at 30°C with gold‐labeled LDL and transferrin, labeled cellular structures represented respectively half and one‐third of the total volume of all single‐membrane bounded endocytotic and electron‐dense vacuoles within the cell.
Eimeria turcicus N. Sp. (Apicomplexa: Eimeriidae) from the Mediterranean Gecko, Hemidactylus turcicus (Sauria: Gekkonidae)
Authors: UPTON STEVE J. , McALLISTER CHRIS T. , FREED PAUL S.
Published: May 2007

ABSTRACT. Eimeria turcicus n. sp. (Apicomplexa: Eimeriidae) is reported from the gall bladder of the Mediterranean gecko, Hemidactylus t. turcicus (Linnaeus, 1758) from the Houston Zoo, Texas, USA. Oocysts of this coccidian are elongate and cylindrical, 38.2 × 17.9 (35.2‐40.8 × 16.8‐20.0)μm, with a smooth, bilayered wall ∼ 1.6 μm thick; shape index 2.1 (1.9‐2.3). A polar granule is present, but a micropyle and oocyst residuum are absent. Sporocysts are ovoid, 11.0 × 8.8 (10.0‐12.0 × 8.0‐9.4) μm, with a smooth, thin wall and suture; shape index 1.3 (1.1‐1.4). Each sporocyst contains a residuum measuring 6.0 × 5.1 (4.8‐8.0 × 4.8‐6.4) μm, additional residual granules scattered among the sporozoites, and two sporozoites that are normally arranged head‐to‐tail within the sporocyst. Each sporozoite contains a single, ovoid, posterior refractile body and a central nucleus.
The Functional and Evolutionary Significance of the Ultrastructure of the Ophryoscolecidae (Order Entodiniomorphida)1
Authors: FURNESS D. N. , BUTLER R. D.
Published: May 2007

ABSTRACT. Ophryoscolecid ciliates from the order Entodiniomorphida show a series of morphological types which have been interpreted as an evolutionary lineage. In this study, ultrastructural information from three species—the ancestral Entodinium, intermediate Eudiplodinium maggii, and the advanced Epidinium—has been evaluated in terms of ophryoscolecid evolution. The infraciliature, nuclei, contractile vacuoles, cortex, and cytoplasm are all very similar and sometimes indistinguishable among the three species, suggesting a close relationship. The cytoalimentary system, however, shows considerable interspecific variation. The cytopharynx differs in position and extent of microtubules and microfilaments, varying in appearance from a microtubular to a microfilament‐based mechanism while retaining similar component structures. The esophagus, a zone of cytoplasm extending from the cytopharynx and delimited by a microtubular/fibrillar wall, is rudimentary in Entodinium, sac‐like in Eudiplodinium, and tube‐like in Epidinium, where it also has convoluted walls and a sheath of fibrous material that suggest an expansible‐contractile structure. These variations have been related to type of food particle ingested. The capability of the cytoalimentary systems seems to be increased so that the more advanced forms can exploit a food resource, in the form of large plant fragments in the ruminal fluid, not available to the simpler, ancestral forms, which tend to ingest small particles such as bacteria and starch grains. The original evolutionary lineage based on morphological studies using light microscopy is supported by our observations, in these three forms, of ultrastructural variations in the cytopharynx and in their relationship with diet via possible ingestion mechanisms. Additional support for this evolutionary analysis comes from preliminary studies of other ophryoscolecids in which the cytoalimentary organization is consistent with their positions relative to one another in the evolutionary scheme.
Membrane Dynamics of the Contractile Vacuole Complex of Paramecium1
Authors: ALLEN RICHARD D. , FOK AGNES K.
Published: May 2007

ABSTRACT. Membrane dynamics of the contractile vacuole complex of Paramecium were investigated using conventional electron microscopy of cells so that the vacuoles were serial‐sectioned longitudinally and transversely. During systole, vacuolar membrane collapses first into flattened cisternae which undergo further modification into a mass of interconnected small membrane tubules. These tubules retain their connections with the radiating microtubular ribbons; consequently they are found only in the poleward hemisphere. Permanent connections between ampullae and the collapsed vacuole membrane could not be verified nor was a sphincter‐like mechanism for closing such a junction observed. Membranes of the ampullae and the collecting canals also collapse to varying extents into arrays of tubules that remain bound to microtubular ribbons during diastole. Thus vacuole, ampullae, and collecting canal membranes all assume tubular forms when internal volume is at a minimum. Having failed to observe a microfilamentous encasement of the vacuole, we suggest that an alternative mechanism for the “contractile” function should be sought. One such is based on fluid volume increase and fluid flow within transiently interconnected tubular membrane systems that cycle between a tubular and a planar membrane form as internal volume is periodically increased and reduced. The driving force for this mechanism might best be sought in the molecular structure of the membranes of the contractile vacuole complex.
Evidence of Extensive Fragmentation of Macronuclear DNA in Two Non‐Hypotrichous Ciliates
Authors: METENIER G. , HUFSCHMID J.‐D.
Published: May 2007

ABSTRACT. Total cellular DNA from the ciliates Halteria grandinella and Trithigmostoma cucullulus was analyzed by agarose gel electrophoresis. The macronuclear DNA (MAC DNA) of Halteria consisted of very small fragments, which suggests that the MAC DNA organization of oligotrichs resembles that of hypotrichs (gene‐sized DNA). The MAC DNA of Trithigmostoma, a cyrtophorid having a heteromeric MAC, also existed as small fragments, but with a significant fraction (20–30%) comprising larger molecules unresolved by the method used. It is suggested that MAC heteromery is related to the differential localization of two kinds of DNA molecules of different sizes.
Ultrastructural Features of the Apical Complex, Pellicle, and Membranes Investing the Gamonts of Haemogregarina magna (Apicomplexa: Adeleina)1
Authors: PATERSON W. B. , DESSER S. S. , BARTA J. R.
Published: May 2007

ABSTRACT. Mature gamonts of Haemogregarina magna lie within a type of parasitophorous vacuole (Pv) apparently unique to the haemogregarines. The cytoplasm of infected erythrocytes was separated from the parasite by two Pv membranes. An additional membrane, coated on both sides with electron‐dense material, closely invested the gamonts. The apical complex of the gamonts includes a conoid, two preconoidal rings, and an elaborate polar ring complex. The latter consisted of the polar ring and approximately 78 posteriorly directed, radially arranged, “tine‐like” structures which fuse as they merge anteriorly into the polar ring. Freeze fracture replicas demonstrated that the pellicle of gamonts of H. magna was structurally similar to that of other apicomplexans. The closely apposed inner membranes of the pellicle formed plates which were arranged into strips along the long axis of the gamont. Calculations indicated that 13 such strips are found around the circumference of the gamonts with about six subpellicular microtubules associated with the inner surface of each strip. Gamonts of H. magna share many structural similarities with the kinetes, ookinetes, and sporokinetes of other apicomplexans. We propose that the conoid and polar ring complex are fundamental features of all apicomplexan “kinetes.”
Lagenophrys anticthos N. Sp. and L. aegleae Mouchet‐Bennati, 1932 (Ciliophora, Peritricha, Lagenophryidae), Ectocommensals of South American Crustaceans1
Authors: CLAMP JOHN C.
Published: May 2007

ABSTRACT. Lagenophrys anticthos n. sp. resembles L. aegleae Mouchet‐Bennati; however, the two species are distinguished from one another by differences in the structure of the lorica aperture. Similarities in the shape of the lorica and macronucleus indicate a close phylogenetic relationship between L. anticthos and L. aegleae. The size of L. anticthos varies greatly within a population, and it is unclear whether this can be attributed to genetic differences or to environmental factors. In L. anticthos, variation in the form of the lips of the lorica aperture is correlated with variation in size. The brown, iron‐rich incrustations observed around the loricae of L. aegleae by an earlier worker were not seen, indicating that the incrustations do not play a role in the symbiosis between L. aegleae and its host as was previously thought.
Intranasal Immunization of Mice Against Naegleria fowleri1
Authors: BUSH LINDA E. , JOHN DAVID T.
Published: May 2007

ABSTRACT. The purpose of this research was to determine whether mice could be protected from lethal challenge with Naegleria fowleri by prior intranasal exposure to pathogenic and nonpathogenic Naegleria. Mortality ranged from 0 to 100% for mice inoculated intranasally (i.n.) with 5 × 103 amebae of 13 human isolates of N. fowleri. Mice were immunized and challenged i.n. using live amebae of strains of low, medium, and high virulence. The greatest protection against lethal challenge was afforded by three immunizing doses of 103 amebae per dose of the strain of medium virulence. Nonpathogenic N. gruberi also was used to immunize mice i.n. against lethal challenge with N. fowleri. Protection was greater following immunization with N. gruberi than it was after immunization with N. fowleri, suggesting that nonpathogenic N. gruberi may be a better immunogen in protecting mice against lethal naeglerial challenge.
Cryopreservation of Leucocytozoon caulleryi Sporozoites
Authors: MORII T. , MATSUI T. , IIJIMA T. , ABE N. , YOSHIZAWA A. , CHIKATSUNE M. , WATANABE M.
Published: May 2007

Leucocytozoon caulleryi sporozoites that had been stored at ‐ 196° C or ‐80° C for 6 or 12 months in Eagle's minimum essential medium or Medium 199 supplemented with 5% glycerol and 10% chicken serum showed infectivity to chickens. Glycerol at a concentration of 10% and dimethyl sulfoxide at 10% and 5% were found to be ineffective cryoprotective agents for the low temperature preservation of sporozoites. Sporozoites isolated from the intact females of Culicoides arakawae, which had been stored at ‐80° C for 6 or 12 months without cryoprotective agents, retained their infectivity. No differences were observed in the prepatent period, duration of parasitemia, and presence of serum‐soluble antigens between chickens infected with frozen sporozoites and those infected with fresh sporozoites.
Effects of Glycogen on Food Vacuole Formation in Parameium caudatum
Authors: FUKUSHIMA SHINICHI , OGAWA HIROSHI , NISHIKAWA TOMOYO , SASAGAWA SUKENARI
Published: May 2007

Paramecium caudatum syngen 3 could not reproduce in the defined medium (DM) which had been developed for P. octaurelia stock 299, but we succeeded in culturing it in DM supplemented with glycogen. The number of food vacuoles which formed in 5 and 10 min at 25°C in the DM alone was greater in comparison with the DM supplemented with glycogen. These results showed that the high molecular weight substance which needed to be added to a defined medium for the cultivation of Paramecium did not always support cell reproduction by stimulating food vacuole formation.
Ribosome‐Inactivating Proteins from Plants Inhibit Ribosome Activity of Trypanosoma and Leishmania1
Authors: CENINI PIETRO , BOLOGNESI ANDREA , STIRPE FIORENZO
Published: May 2007

Ribosomes from Trypanosoma brucei rhodesiense and from Leishmania infantum were isolated and optimal conditions for in vitro translation were established. The effect of ribosome‐inactivating proteins extracted from several plants was then assessed in order to identify those suitable for the preparation of immunotoxins against these organisms. Ribosomes from both species were inactivated by some ribosome‐inactivating proteins (dianthins, saporins, pokeweed antiviral proteins, and the ribosome‐inactivating chain of abrin). The similarity of the effects on the ribosomes from the two species examined indicates that ribosome‐inactivating proteins should also be effective in a similar way on ribosomes from other species of Trypanosoma and Leishmania.
A Survey of Lectin Binding in Paramecium1
Authors: ALLEN RICHARD D. , UENO MARILYNN S. , FOK AGNES K.
Published: May 2007

To better understand the general distribution of glycoproteins and the distribution of specific glycoprotein‐bound sugar residues in Paramecium, a survey of the binding pattern of selected lectins was carried out in P. tetraurelia, P. caudatum, and P. multimicronucleatum. Lectins studied were concanavalin A (Con A), Griffonia simplicifolia agglutinins I and II (GS I and GS II), wheat germ agglutinin (WGA), Ulex europaeus (UEA I), peanut agglutinin (PNA), Ricinis communis toxin (RCA60) and agglutinin (RCA120), soybean agglutinin (SBA), Bauhinia purpurea agglutinin (BPA), Dolichos biflorus agglutinin (DBA), and Maclura pomifera agglutinin (MPA). Those giving the most distinctive patterns were Con A, GS II, WGA, UEA I, and PNA. No significant differences were found between the three species. Concanavalin A, a mannose/glucose‐binding lectin, diffusely labeled the cell surface and cytoplasm and, unexpectedly, the nuclear envelopes. Events of nuclear division, and nuclear size and number were thus revealed. Both WGA and GS II, which are N‐acetylglucosamine‐binding lectins, labeled trichocyst tips, the cell surface, and the oral region, revealing stages of stomatogenesis. The lectin WGA, in addition, labeled the compartments of the phagosome‐lysosome system. The lectin PNA, an N‐acetyl galactosamine/galactose‐binding protein, was very specific for digestive vacuoles. Finally, UEA I, a fucose‐binding lectin, brightly labeled trichocysts, both their tips and body outlines. We conclude that a judicious choice of lectins can be used to localize glycoproteins and specific sugar residues as well as to study certain events of nuclear division, cellular morphogenesis, trichocyst discharge, and events in the digestive cycle of Paramecium.
Three New Species of Eimeria (Apicomplexa: Eimeriidae) from Nerodia rhombifem (Serpentes: Colubridae) from Texas1
Authors: UPTON STEVE J. , McALLISTER CHRIS T.
Published: May 2007

Three new species of Eimeria (Apicomplexa: Eimeriidae) are described from the intestinal contents of Nerodia rhombifera (Serpentes: Colubridae) from Texas. Oocysts of Eimeria infirmus are irregular in shape, 11.6 (8.8–14.4) μm in diameter, with a smooth, thin wall that ruptures easily, releasing free sporocysts. A small polar granule is usually present, but a micropyle and oocyst residuum are absent. Sporocysts are bean‐shaped with one side flattened slightly, 9.1 times 5.0 (7.2–10.4 times 4.4–5.8) μm, with what may be a Stieda body consisting of a slight thickening of one end of the sporocyst. Each sporocyst contains a spherical or ellipsoid residuum and sporozoites, each with a single, posterior refractile body. Oocysts of Eimeria rhombifera are spherical or subspherical, 13.1 times 12.6 (12.0–14.4 times 11.2–14.4) μm, with a smooth, frail wall. A polar granule is present, but a micropyle and oocyst residuum are absent. Sporocysts are ovoid, 8.8 times 5.5 (8.0–9.6 times 5.0–6.0) μm, each with a Stieda body. Each sporocyst contains a spherical or subspherical residuum and sporozoites, each with a single posterior refractile body. Oocysts of Eimeria tenuis are ellipsoidal in shape, 17.2 times 10.8 (15.2–20.8 times 9.6–12.0) μm, with a smooth, thin wall. A polar granule and oocyst residuum are present, but a micropyle is absent. Sporocysts are elongate, 13.2 times 4.9(11.2–15.2 times 4.4–5.6) μm, each with a Stieda body consisting of a thickening of the sporocyst wall. Each sporocyst contains a spherical or subspherical residuum and sporozoites with anterior and posterior refractile bodies.
Fine Structure of the Shell Wall in the Soil Testate Amoeba Cyclopyxis kahli (Rhizopoda)1
Authors: OGDEN GOLIN G.
Published: May 2007

The common soil testate amoeba, Cyclopyxis kahli, is capable of building a complete organic shell when grown in culture in the absence of agglutinate material. Such shells are morphologically similar to agglutinate shells except in the structure and diameter of the aperture. Chemical analysis of organic shells suggests that the main inorganic elements present are calcium and iron. Comparisons are made with similar analyses of organic shells from other agglutinate species. This is the first report of a significant change in shell architecture due to agglutinate material.
Cortical Morphogenesis during Excystment in Histriculus similis (Hypotrichida: Oxytrichidae)1
Authors: CALVO PURIFICACION , MARTIN JESUS , DELGADO PILAR , TORRES ANTONIO
Published: May 2007

ABSTRACT Cortical morphogenesis during excystment in Histriculus similis has been studied by light microscopy of preparations impregnated with silver proteinate (protargol). This morphogenesis shows clear differences from cortical morphogenesis during division. The oral, paroral, and fronto‐ventro‐transverse primordia originate from an extensive field of kinetosomes. The marginal cirral primordia and the dorsal bristle primordia appear at an early stage of morphogenesis. The left marginal cirral primordium originates from the oral primordium.
Tyzzeria chalcides N. Sp. from the Ocellated Skink, Chalcides ocellatus1
Authors: PROBERT A. J. , ROBERTS A. H. , WILSON I. B.
Published: May 2007

ABSTRACT A new species of coccidium, Tyzzeria chalcides, is described from the ocellated skink, Chalcides ocellatus, from Egypt. Meronts occur in the epithelial cells of the bile ducts and gamonts within the epithelial cells of the gall bladder. Fully sporulated oocysts are cylindrical (L/W ratio 1.88) without a micropyle, oocyst residuum, or polar granule and contain eight spindle‐shaped sporozoites and no sporocysts. Sporulation is completed within the gall bladder lumen. Comparison with other species of the genus found in reptiles indicates that it is a new species.
Trypanosoma brucei gambiense and T. b. rhodesiense: Concanavalin A Binding to the Membrane and Flagellar Pocket of Bloodstream and Procyclic Forms1
Authors: BALBER ANDREW E. , FROMMEL THOMAS O.
Published: May 2007

ABSTRACT We have measured binding of fluorescein‐conjugated succinyl‐concanavalin A (Fl‐s‐Con A) to bloodstream and procyclic forms of Trypanosoma brucei gambiense and to bloodstream forms of T. b. rhodesiense by flow cytofluorimetry. Bloodstream forms bound an order of magnitude less lectin than procyclic forms. Trypsin‐treating cells enhanced binding of Fl‐s‐Con A to bloodstream forms 3–16‐fold depending on the strain and the length of trypsinization but had little effect on Fl‐s‐Con A binding by procyclics. The trypsinization protocol used did not remove major common glycoproteins detected on lectin blots of either life cycle form but removed >95% of the variant specific glycoprotein and fragments derived from this protein of bloodstream forms. Microscopically detectable Fl‐s‐Con A binding to bloodstream forms was confined to the flagellar pocket. Trypsinized bloodstream forms and procyclics bound Fl‐s‐Con A in the flagellar pocket, on the flagellum, and on the cell surface. Lectin remained cell associated but appeared to redistribute towards the flagellum and pocket when cells that had bound lectin on ice were subsequently incubated at physiological temperatures. The Fl‐s‐Con A binding had specificity characteristic of the interaction between the lectin and oligosaccharides. These results are consistent with the hypothesis that the variant specific surface glycoprotein blocks binding of the lectin to surface glycoproteins of bloodstream forms and suggest that concanavalin A‐binding glycoproteins are abundant in the flagellar pocket of both life cycle forms.
A Comparative Study of the Storage Carbohydrate Granules from Euglena (Euglenida) and Pavlova (Prymnesiida)1,2
Authors: KISS JOHN Z. , TRIEMER RICHARD E.
Published: May 2007

ABSTRACT The storage carbohydrate granules from Euglena and Pavlova were compared by light and electron microscopy. Freezeetch studies demonstrated that while both types of granules are crystalline, they have different structures. The elemental microfibril of the euglenoid granule measures 4 nm, and the elemental striation of the granule from Pavlova is 22 nm. The granules each have a unique X‐ray diffraction pattern. The storage carbohydrate granules from Pavlova are not the same as paramyton, and the term “paramylon” should be reserved for the euglenoid storage carbohydrate.
DNA Damage and Repair in Stylonychia lemnae (Ciliata, Protozoa)1
Authors: AMMERMANN DIETER
Published: May 2007

ABSTRACT Irradiation with X rays, UV irradiation after incorporation of bromodeoxyuridine (BU) into the DNA, and cis‐platinum (cis‐Pt) treatment each cause the loss of micronuclei of Stylonychia lemnae while the macronuclei are not severely affected. The abilities of both nuclei to repair DNA were investigated. Unscheduled DNA synthesis could not be demonstrated after X‐ray irradiation, but it was found after treatment with BU/UV and cis‐Pt in macro‐ and micronuclei. The extent of the repair process in the micro‐ and macronuclei was alike, as indicated by grain counts of [6‐3H]thymidine‐treated cells. One reason for the different sensitivity of both nuclei to DNA‐damaging treatment may be the different number of gene copies in the macro‐ and micronuclei.
Note to Establish as a New Species a Previously Reported Microsporidium of Philippine Prawns1
Authors: ENRIQUEZ GLORIA L. , SPRAGUE VICTOR
Published: May 2007

ABSTRACT A previously reported microsporidium in Penaeus merguiensis de Man, 1888 (Decapoda, Penaeidae), in the Philippines has been identified as a species of Agmasoma Hazard & Oldacre, 1975, and named Agmasoma aquinoae n. sp. (Microsporida, Thelohaniidae).
Persistence of Oral Structures in the Sexual Process of Amicronucleate Paramecium tetraurelia
Authors: NG STEPHEN F.
Published: May 2007

ABSTRACT In the sexual process, amicronucleate Paramecium tetraurelia, unlike micronucleates, fail to produce an oral apparatus, but resorb the pre‐existing one. Exceptions were found in some amicronucleate cell lines in which about 1% of the cells possessed oral structures, including pieces of oral membranelles, sometimes complete with buccal cavity, after autogamy or conjugation. By following oral development in the sexual process in some detail, the present study supports the view that these oral structures are derived from the pre‐existing oral apparatus and not newly developed from the oral primordium. The possible involvement of the micronucleus and the pre‐existing oral apparatus in oral resorption is discussed. The possession of a functional oral apparatus after the sexual process may open up a new evolutionary avenue to the amicronucleates.
Circular Ribosomal RNA Genes Are a General Feature of Schizopyrenid Amoebae
Authors: CLARK C. GRAHAM , CROSS GEORGE A. M.
Published: May 2007

ABSTRACT We have recently shown that the ribosomal RNA genes of the amoebo‐flagellate Naegleria gruberi Schardinger, 1899, strain NEG‐M are carried exclusively on a 14 kilobasepair plasmid. To explore the distribution of this unique gene arrangement, we have examined another strain of N. gruberi and four other species from the order Schizopyrenida. All have this unusual gene arrangement although the size of the plasmid varies widely. Species groups based on morphological criteria do not agree with those resulting from comparison of plasmid restriction enzyme patterns.
Eimeria ornata N. Sp. (Apicomplexa: Eimeriidae) from the Ornate Box Turtle, Terrapene ornata ornata (Reptilia: Testudines), in Texas
Authors: McALLISTER CHRIS T. , UPTON STEVE J.
Published: May 2007

Eimeria ornata n. sp. is described from the feces of 6/16 (37.5%) ornate box turtles, Terrapene ornata ornata, in northcentral Texas. Endogenously sporulated oocysts are ellipsoid 17.9 × 15.7(16‐21 × 14‐18) μm, with a thin, single‐layered wall; shape index 1.14 (1.0‐1.3). A micropyle is absent but a polar granule was present in one third of the oocysts. An oocyst residuum was present, consisting of numerous small globules situated either in a distinct mass or scattered within the oocyst. The sporocysts are elongate, 11.1 × 5.4 (9‐13 × 5‐6) μm, with an indistinct Stieda body at 1 pole. A sporocyst residuum is present, consisting either as a compact mass or as scattered granules. The sporozoites are elongate, 9.5 × 2.0 (8‐12 × 2) μm, in situ, with spherical anterior and posterior refractile bodies. The new species is distinguished from the similar Eimeria carri Ernst & Forrester, 1973, from eastern box turtles, T. Carolina, by slight differences in oocyst morphology and endogenous sporulation.
Ultrastructure of Tachyzoites, Bradyzoites and Tissue Cysts of Neospora caninum
Authors: SPEER C. A. , DUBEY J. P.
Published: May 2007

. Dividing tachyzoites of Neospora caninum were 4x3 μm and had ultrastructural characteristics typical for the cyst‐forming coccidia. Unusual ultrastructural characteristics of fully‐formed tachyzoites included no micropores, 8–12 anterior and 4–6 posterior rhoptries, and a few posterior micronemes. Most tachyzoites were located free in the host cell cytoplasm; only a few occurred within a parasitophorous vacuole. Parasite multiplication appeared to be rapid because most organisms were in various stages of endodyogeny. Neural tissue cysts of N. caninum were 24.3 × 19.2 μm and contained 50–200 bradyzoites (7.3 × 1.5 μm), which lacked micropores. The cyst wall was 0.74–1.12 μm thick and consisted of the primary cyst wall (the parasitophorous vacuole membrane) and a thick granular layer with electron‐dense vesicles.
Binding of Lectins to Culture and Vector Forms of Trypanosoma rangeli Tejera, 1920 (Protozoa, Kinetoplastida) and to Structures of the Vector Gut
Authors: RUDIN W. , SCHWARZENBACH M. , HECKER H.
Published: May 2007

Culture forms of Trypanosoma rangeli could be agglutinated with Canavalia ensiformis (Con A) lectin and, less effectively with Pisum sativum agglutinin (PEA), at a concentration of 200 μg/ml. Ricinus communis agglutinin I (RCA I) agglutinated trypanosomes only if they were not previously washed with physiological Ringer's solution. Three other lectins did not react with the same parasite forms. Direct or indirect lectin‐gold labeling techniques were applied to LR‐White embedded thin sections of T. rangeli culture forms and to forms in the gut, hemolymph, and salivary glands of Rhodnius prolixus. Under these conditions, Con A was the only lectin out of 9 that bound to the surface of trypanosomes from culture and from the bug hemolymph. Con A did not react with any midgut or salivary gland forms. The preservation of the biological activity of the lectin‐gold complexes that did not bind to the parasite surface was confirmed by reactions with structures of the invertebrate host.
Mechanism of Long Slender (LS) to Short Stumpy (SS) Transformation in the African Trypanosomes
Authors: SEED JOHN R. , SECHELSKI JOHN B.
Published: May 2007

The transformation of the long slender to the short stumpy stages of the African trypanosomes is an essential part of the trypanosome life cycle. Four possible mechanisms which could control this event have been investigated. It has been shown that (a) the dividing long slender to non‐dividing short stumpy transition is not a programmed event in the trypanosome life cycle; nor (b) would it appear to be initiated by some form of cell to cell contact inhibition of growth. In addition, evidence is presented which would suggest that (c) the transition is not started by the depletion of a critical growth nutrient from the environment during the growth of the trypanosomes. The last possibility (d) considered is that during trypanosome growth, a growth inhibitor‐short stumpy inducer accumulates in the trypanosomes’environment. Evidence is presented which shows that plasma from infected animals can inhibit the incorporation of thymidine by the trypanosomes. These data are consistent with the suggestion of an exogenous growth inhibitor accumulating during the infection.
Changes in Cell Surface Anionogenic Groups Induced by Propranolol in Herpetomonas muscarum muscarum
Authors: LOPES ANGELA HAMPSHIRE C. S. , FILHO FERNANDO COSTA E SILVA , ALVIANO CELUTA S. , JURKIEWICZ ARON , ANGLUSTER JAYME , DE SOUZA WANDERLEY
Published: May 2007

The effects of propranolol (10−3 mM) on the surface anionic groups of Herpetomonas muscarum muscarum were analysed by cell electrophoresis, by ultrastructural cytochemistry and by identification of sialic acids using paper chromatography. Differentiation of H. muscarum muscarum induced by propranolol treatment caused a significant increase in the net negative surface charge. Binding of cationized ferritin (CF) and colloidal iron hydroxide particles was observed at the cell surface of both untreated and propranolol‐treated cells. In cells incubated in the presence of the drug the CF particles were distributed in all membrane regions. However, there were small areas where the particles were absent. In H. muscarum muscarum exposed to propranolol the density of residues of sialic acid per cell was higher, and the agglutinating activity with Sendai virus was more intense. However, the pattern of sialic acid, characterized by the presence of N‐acetylneuraminic acid derivative, was not modified upon cell interaction with the drug. Treatment of both control and propranolol‐treated protozoa with neuraminidase significantly reduced the surface charge. These findings suggest that sialic acid residues are the major anionogenic groups exposed on the surface of H. muscarum muscarum.
Marine Amoebae from Waters of Northwest Spain, with Comments on a Potentially Pathogenic Euryhaline Species
Authors: FERNANDEZ M‐CRISTINA ARIAS , CRESPO ESPERANZA PANIAGUA , MALLEN MARGARITA MARTI , ARES M. P. MONICA PENAS , CASAS M'LUISA CASTRO
Published: May 2007

Of 17 species of free‐living amoebae identified in various samples of salt water, only 1. Acanthamoeba polyphaga, is known to be a potential pathogen. While no deaths occurred when laboratory animals were inoculated with A. polyphaga to test for pathogenicity, the protozoa were present in the brain, liver and lungs of some but not all of the animals.
Coccidian Parasites (Apicomplexa: Eimeriidae) of Nerodia spp. (Serpentes: Colubridae), with a Description of a New Species of Eimeria
Authors: MCALLISTER CHRIS T. , UPTON STEVE J.
Published: May 2007

Eimeria conanli n. sp. (Apicomplexa: Eimeriidae) is described from intestinal contents and feces of Nerodia erythrogaster transversa and N harteri harteri from northcentral Texas. Oocysts of the new species are ellipsoid in shape. 17.9 × 13.0(15–21 × 12–15) μm, with a smooth, thin, single‐layered wall; shape index 1.4 (1.2–1.5). One to several (usually 2) polar granule(s) and an oocyst residuum are present, but a micropyie is absent. Sporocysts are elongate, 12.9 × 5.2 (13–15 × 5–6) ‐m, apparently without a true Stieda body structure. Each sporoeyst contains an ellipsoid residuum, 3.9 × 3.2 (3–6 × 2–4) μm, and elongate sporozoites, 11.4 × 2.5 (10–14 × 2–3) μm in situ, each with a spherical or subspherical anterior refractile body and spherical to ellipsoid posterior refractile body. In addition to the new species, oocysts of 4 previously described eimerians from colubrid snakes were found in these hosts.
Soluble Poison of Pseudokeronopsis rubra Affects Inward Current in Euplotes vannus
Authors: LUEKEN WOLFGANG , UHLIG GOTRAM , KRÜJPPEL THOMAS
Published: May 2007

ABSTRACT. The marine ciliate Euplotes vannus was used to lest whether keronopsin, the water‐soluble component of (he toxic pigment complex from Pseudokeronopsis rubra, narcotizes cells by affecting ion conductance. Keronopsin delays the rate of rise in the regenerative component of action potentials under constant current injection. In depolarizing voltage steps it reduces the rate of rise and the final amplitude of the initial Ca2+ inward current. Normal traits are restored after change to keronopsin‐free medium. Effects on locomotory behavior, spontaneous membrane depolarization, action potential, and inward current, all provide evidence that keronopsin acts on cells by obstructing Ca2+ influx.
Lorica Production in Choanoflagellates–A Model System for Investigating the Mechanics, Controls and Dynamics of Secretion
Authors: LEADBEATER BARRY S. C.
Published: May 2007

BIOMINERALIZATION is the process by which living organisms assemble structures from naturally occurring inorganic compounds. Mineral deposition is common and widespread amongst Protozoa and in most instances the mineralized structures provide skeletal support and protection for softer organic parts [10]. The 2 most common minerals to be deposited by Protozoa are silica and calcium carbonate. Groups of Protozoa that deposit silica, which we are concerned with here, include the diatoms, chrysophytes, choanoflagellates, Radiolar‐ia, Heliozoa and testate amoebae [10].

In the majority of silica‐depositing protista, silica is taken up from the medium in the form of monomelic orthosilicic acid Si(OH)4 (soluble reactive silicate) and deposited as amorphous, polymerised biogenic silica or opal within membrane‐bounded vesicles known as silica deposition vesicles (SDV). Often biogenic silica is characteristically patterned and ornamented and for most protozoan groups the morphology of silicified parts is of prime taxonomic importance.

By far the most extensively studied group of silica‐depositing organisms are the diatoms [1, 12, 13]. To date most of our knowledge of silica metabolism in protists has been based on investigations into this group. Diatoms require silica for the production of their frustules. Uptake and deposition of silica occurs within a closely denned portion of the cell cycle, between nuclear division and cell separation. It occupies about ± of the cell cycle and without an adequate supply of silica diatoms are unable to produce new frustule valves with the result that cell division cannot be completed. Diatoms, therefore, have an obligate requirement for silica and without this nutrient they cease to grow [11].

In contrast to diatoms a number of other silica‐depositing protistan groups, such as loricate choanoflagellates and certain chrysophytes, have a facultative requirement for silica. In the past decade the ultras true ture, physiology and ecology of loricate choanoflagellates have been extensively studied by a number of different workers [7] and the significance of these studies to our understanding of the mechanisms, controls and dynamics of silica secretion is summarised and discussed here.
Constitutive Secretion of Acid Hydrolases in Tetrahymena thermophila
Authors: TIEDTKE ARNO , RASMUSSEN LEIF
Published: May 2007

THE role of lysosomal enzymes in intracellular digestion is now well established [11]. Most often we think of lysosomal hydrolases in catabolism of endogenous or foreign material taken up by endocytosis. There is however, a number of reports dealing with the release of acid hydrolases into the extracellular fluid in a variety of eukaryote cells. These cells range from Saccharomyces cerevisiae [15], Dictyostelium discoideum [10], Leishmania donovani [20], Acanthamoeba castellani [22], Entamoeba histolytica [12, 31], and species of Tetrahymena [1–3, 6] to mammalian cells in culture [49]. Concerning the latter, fibroblasts and hepatocytes in culture release acid hydrolases to the extracellular medium, but only if the synthesis of a specific recognition marker is impaired in the cells. This marker (man‐nose‐6‐phosphate) is used for receptor mediated segregation of lysosomal enzymes into the lysosomal compartments. If the receptor or the marker are lacking, the hydrolases fail to enter the lysosomal compartment, and are secreted in immature form together with molecules belonging to the constitutive secretory pathway of the cells [8, 49]. Such a release of acid hydrolases seems to occur spontaneously from mammalian osteoclasts [4]. Macrophages, on the other hand, need a specific stimulation for their release process [40]. In lower eukaryotes the release may
Morphometries and Redescription of Trypanoplasma borreli Laveran & Mesnil, 1901 (Mastigophora, Kinetoplastida) from Experimentally Infected Common Carp (Cyprinus carpio L.)
Authors: KRUSE PETER , STEINHAGEN DIETER , KÖRTING WOLFGANG , FRIEDHOFF KARL T.
Published: May 2007

.Morphological development of cloned Trypanoplasma borreli was studied during the course of experimental infections in common carp. During the course of infection the cell dimensions of T. borreli showed high variability. At the beginning of parasitemia at day 8 p.i. (post inoculation) small and slender T. borreli predominated: surface area (SA, determined using a polar planimeter) 48.9 ± 13.1 Mm2; shape index (SI, length/width) 7.8 + 2.1 (n = 110). During the exponential growth phase until day 13 p.i. the size further decreased significantly (P < 1%): SA 29.9 ± 9.5 μm: (n = 109). During the transition of parasitemia from exponential growth to the chronic phase the size of T. borreli enlarged significantly (P < 1%) and it became stumpy in shape. Day 15 p.i.: SA 63.2 ± 15.8 μm2; SI 4.2 ± 1.0 (n = 51). During the chronic phase significantly (P < 1%) larger trypanoplasms predominated: day 41 p.i. SA 90.6 ± 22.7 μm2, SI 4.9 ± 1.1 (n = 221). Further samples showed only moderate variability of cell dimensions during this phase of parasitemia. Measurements of dimensions of lrinetoplast and nucleus and length of flagella varied in a similar manner. The position of the kinetoplast remained unchanged, while the nucleus had a more anterior position in the chronic phase. Experimental infections of various cyprinids were successful, perch and rainbow trout were not susceptible to experimental infections with T. borreli. Using these data a redescription of T. borreli is given.
Trypanosomatids, Other Than Phytomonas spp., Isolated and Cultured from Fruit
Authors: CONCHON IVETE , CAMPANER MAHTA , SBRAVAT CLIZETE , CAMARGO E. PLESSMANN
Published: May 2007

Trypanosomatids were isolated from edible fruit. One of the isolates (from tangerine) presented a set of enzymes for the metabolism of arginine‐ornithine similar to that of Leptomonas spp., and failed to be recognized by monoclonal antibodies specific for Phytomonas spp. The possibility that trypanosomatids other than Phytomonas spp. could infect fruit was further examined by inoculating tomatoes with species of Crithidia, Leptomonas and Herpetomonas. Some of these flagellates multiplied in tomatoes. Besides, house flies became infected with Crithidia sp. when fed on tomatoes experimentally inoculated with this flagellate. Therefore, isolation of a trypanosomatid from a plant should not constitute an absolute criterion for placing it in the genus Phytomonas.
The Site Specificity of Two Species of Gregarina in Tenebrio molitor Larvae
Authors: RUHNKE T. R. , JANOVY J.
Published: May 2007

The site specificity of the apicomplexans Gregarina cuneata and Gregarina sleini, in larval Tenebrio molitor was investigated. Gregarina cuneata was found to inhabit the anteriormost region of the larval midgut, while G. steini was restricted to the posterior portion of the intestine. The site specificity of the pair was conserved in single and concurrent infections. Interspecific interactions do not seem to be presently responsible for the resource partitioning by the 2 gregarine species. Key words. Gregarina, site specificity, Tenebrio molitor.
Pathogenesis of Sarcocystis falcatula (Apicomplexa: Sarcocystidae) in the Budgerigar (Melopsittacus undulatus). IV. infrastructure of Developing, Mature and Degenerating Sarcocysts
Authors: NEIIJU PAMELA J. G. , SMITH JEROME H. , BOX EDITH D.
Published: May 2007

ABSTRACT. Sarcocysts in cardiac and skeletal muscles of budgerigars (Melopsittacus undulatus) were examined transmission electron microscopically 5 to 168 days after experimental infection with Sarcocystis falcatula. The ultrastnicture of the primary cyst wall, amorphous substance, metrocytes and bradyzoites in developing, degenerating and mature sarcocysts is described and compared with precystic merozoites studied previously. Sufficient morphologic differences between precystic rnerozoites, metrocytes and bradyzoites (cystozoites) were found which seem to justify their semantic differentiation. Significant differences in immature and mature primary cyst wall morphology were encountered. If primary cyst wall morphology is to be used in determination and differentiation of species of Sarcocystis, then caution must be used to employ only mature sarcocysts.
Characterization and Cloning of Pneumocystis carinii Nucleic Acid
Authors: WORLEY MARK A. , IVEY MICHAEL H. , GRAVES DON C.
Published: May 2007

.Large numbers of Pneumocystis carinii (2 × 1010 nuclei) were isolated and separated from the lungs of immunosuppressed rats by an enzymatic (collagenase, hyaluronidase and DNase) digestion procedure. The nucleic acid isolated from this P. carinnii‐enriched preparation was characterized by melting point analysis and RNA‐sizing gels. The GC content of P. carinii DNA was approximately 33% while the rat DNA was 41.4%. In addition, RNA isolated from the P. carinii‐enriched preparation showed unique ribosomal RNA bands of 3.4 kb and 1.8 kb as compared with uninfected rat lung ribosomal RNA which banded at 4.8 and 1.9 kb. Following isolation and fragmentation by sonication, the P. carinii DNA fragments were inserted into the vector, λ gt‐11. The resultant library contained 1.1 × 105 phage, of which 40–45% hybridized to P. carinii DNA but not to rat DNA.
Yeast Glucan in the Cyst Wall of Pneumocystis carinii
Authors: MATSUMOTO YOSHITSUGU , MATSUDA SHINJI , TEGOSHI TATSUYA
Published: May 2007

Uluastraclurally, the cyst wall of Pneumocystis carinii consists of an electron‐dense outer layer, an electron‐lucent middle layer, and an innermost plasmalemma. This is similar in appearance to the cell wall of some yeasts, e.g. Saccharomyces cerevisiae, which consists of an outer dense layer of mannan, a middle lucent layer of β‐1,3‐glucan (yeast glucan) and an innermost plasmalemma. The cyst wall of P. carinii, as well as the cell wall of S. cerevisiae, can be labeled by a variety of methods which stain polysaccharides, such as Gomori's methenamine silver (GMS) and by Aniline blue, a dye which selectively stains β‐l,3‐glucan. The treatment of P. carinii cysts with Zymolyase, which the key enzyme is β1‐l,3‐glucan laminari‐pentaohydrolase, results in lysis of the outer 2 layers of the cyst wall and the loss of positive staining by both GMS and Aniline blue. The lysis of elements of the cyst wall of P. carinii is achieved under the same conditions and concentration at which Zymolyase lyses the outer 2 layers of the cell wall of viable cells of S. cerevisiae. These observations indicate that a major component of the cyst wall of P. carinii is β‐l,3‐glucan.
A Fifteen‐Year Perspective on the In Vitro Culture of Pneumocystis carinii
Authors: PIFER LINDA L.
Published: May 2007

The in vitro cultivation of Pneumocystis carinii in chick lung cell culture made it possible to observe the organism proceeding through its life cycle. It provided the foundation for extensive serocpidcmiologic studies, for in vitro drug screening, and for essential biological, metabolic, and morphologic research. In vitro culture made possible the discovery of P. carinii antigenemia, its biochemical nature, and its relevance to subclinical and clinical infection. Its utility in the presumptive diagnosis of P. carinii pneumonia and in monitoring responses to drug therapy illustrate the value and clinical application of basic research.
Dynamics of Pneumocystis carinii‐Specific Immune Complexes in AIDS Patients with P. carinii Pneumonia
Authors: PIFER LINDA L.
Published: May 2007

Pneumocystis carinii‐specific immune complexes were detected by immunoblot and enzyme‐linked immunosorbent assay (EUSA) in 53% of sera from Acquired Immunodeficiency Syndrome (AIDS) patients with P. carinii pneumonia (PCP). Resolution of glycoprotein antigenemia (50–55 kd = dominant species) appears to correlate with successful PCP drug therapy and recovery. An epitope map has been constructed from im‐munoblots of P. carinii hydrolysates and from human and murine serum containing P. carinii antigens.
S‐Antigen Localization in the Erythrocytic Stages of Plasmodium falciparum
Authors: CULVENOR JANETTA G. , CREWTHER PAULINE E.
Published: May 2007

Localization of the S‐antigen of Plasmodium falciparum isolate FCQ27/PNG, from Papua New Guinea, was studied by post‐embedding immunoelectron microscopy using affinity‐purified rabbit antibodies raised against the repeat region of the antigen. Labelling was found in the parasitophorous vacuole (PV) space of early to late schizonts and in PV‐related vesicles within the erythrocyte cytoplasm of schizont‐infected cells. Other subcellular structures within the erythrocyte cytoplasm were not labelled. After breakdown of the PV membrane, label was observed around the merozoites, consistent with mixing of the PV contents and erythrocyte cytoplasm. The antigen was not found in uninfected cells, ring stages, trophozoites or associated with free merozoites. Antibodies to FCQ27/PNG S‐antigen did not react with other isolates tested, whereas rabbit antibodies to the Palo Alto/Wellcome S‐antigen repeat region reacted with isolates FCR3 and ItG2F6 but not with FCQ27/PNG.
Size Effects on the Uptake of Particles by Populations of Tetrahymena pyriformis Cells
Authors: LAVIN DANIEL P. , HATZIS CHRISTOS , SRIENC FRIEDRICH , FREDRICKSON A. G.
Published: May 2007

Flow cytometry has been used to make direct measurements of rates of uptake of latex microspheres from dilute, monodisperse suspensions by Tetrahymena pyriformis. Measurements were made for five different sizes of microspheres, ranging from 1.09 to 6.17 μm diameter. Fractions of cells in the population that did not ingest the microspheres offered were also determined. In addition, the size distributions, as indicated by the forward angle light scattering intensity which is measured by the instrument, were determined for the whole population and for the subpopulations of cells that did and did not ingest the particles, for each particle size used. It was found that the fraction of cells that did not ingest the particles was small and independent of particle size when this was less than about 2.7 μm, but increased with particle size when particle size was increased above this value. The so‐called maximum clearance rate, which can be calculated from the data, was found to increase monotonically with particle size if it were based only on those cells which actually ingested the particles offered. However, a plot of maximum clearance rate vs. particle size exhibited a maximum if the clearance rate were based on all cells present in the population.