bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphogenetic Pattern in Laurentiella acuminata (Ciliophora, Hypotrichida): Its Significance for the Comprehension of Ontogeny and Phylogeny of Hypotrichous Ciliates1
Authors: MARTIN JESUS , FEDRIANI CONCEPCION , PEREZ‐SILVA JULIO
Published: May 2007

Morphogenetic events during division, physiological reorganization, and postraumatical regeneration, the last being induced both chemically and microsurgically, were studied by light microscopy on protargol‐impregnated specimens of the hypotrichous ciliate, Laurentiella acuminata. Parakinetal stomatogenesis, from transverse cirrus‐1 during division and reorganization, changes during regeneration to a parakinetal one which characterizes more primitive members of Hypotrichida in the S. O. Stichotrichina, but solely when the AZM is damaged. These morphogenetic events a) confirm the previous inclusion of L. acuminata among the Oxytrichidae on the basis of its morphological characters and indicate that it is a primitive species of this family related with the Stichotrichina through genera Pleurotricha and Paraurostyla; b) suggest a synthetic model that explains both the positioning and timing of cortical morphogenesis in the cell cycle. The key point of this model is the attribution to the AZM of a repressive capacity on the stomatogenic area, the last one being positioned according to the system of gradients of morphogenetic activity proposed by Jerka‐Dziadosz to explain location of primordia in urostylids. This repression is manifested not as a gradient, as indicated by De Terra, but as a long‐term repression limited to a certain distance. Simultaneous repression and stimulation occurring in a growing cortex with the AZM remaining constant in size could explain the critical ratio, buccal cortex/somatic cortex, at which stomatogenesis is triggered as indicated by De Terra.
Identification of the Immobilization Antigens of Paramecium by Their Cyanogen Bromide Cleavage Patterns1
Authors: SCHMIDT HELMUT J.
Published: May 2007

Immobilization antigens from 12 serotypes of three stocks of Paramecium tetraurelia and from one serotype of one stock of P. primaurelia were isolated and purified. Purified proteins were cleaved with cyanogen bromide, and the patterns of the fragment peptides were determined by electrophoresis on SDS‐polyacrylamide gels. It was shown that each of the serotypes of stock 51 of P. tetraurelia has an antigen that produces a characteristic and unique pattern. Consequently, the antigens can be identified by their patterns. Antigens from the allelic serotypes tested had identical patterns. The method is sensitive enough for the investigation of small sample volumes, and useful as a simple biochemical technique for the identification of serotypes.
Intracellular Bubble Formation: Differences in Gas Supersaturation Tolerances Between Tetrahymena and Euglena1
Authors: HEMMINGSEN BARBARA B. , HEMMINGSEN EDVARD A.
Published: May 2007

Cells of Tetrahymena pyriformis, T. thermophila, and Euglena gracilis were saturated with nitrogen gas at pressures up to 300 atm and rapidly decompressed. Damage was assessed by measuring post‐decompression cell fragmentation or viability. Occurrence of intracellular bubbles was determined by cinephotomicrography performed during the decompression or by direct observations afterwards. The extreme gas supersaturations induced led to intracellular bubble formation and rupture in cells of Tetrahymena that contained food vacuoles, but only with supersaturations of 175 atm or higher; 225 atm left few cells intact. Bubbles were never observed in cells of Euglena or in Tetrahymena cells freed of food vacuoles, even when they were decompressed from substantially higher nitrogen supersaturations. Cells of Euglena were most resistant and were unaffected by supersaturations up to 250 atm.
Structure of Cyst Wall Precursors and Kinetics of Their Appearance During the Encystment of Laurentiella acuminata (Hypotrichida, Oxytrichidae)1
Authors: GUTIÉRREZ JUAN C. , TORRES A. , PEREZ‐SILVA J.
Published: May 2007

The encystment of Laurenliella acuminata was divided into five stages: stage A (precystic semitransparent cell with dark‐globules), stage B (precystic transparent cell), stage C (precystic pigmented cell), stage D (spherical shape without cyst wall) and stage E (young resting cyst), on the basis of observations of changes in morphology and pigmentation during encystment. The duration of these stages was also established. Observations by electron microscopy confirmed that the cyst wall, composed of four layers, is derived from different kinds of precursors which are synthesized “de novo.” The ectocyst precursors are composed of stacks of between 5 and 12 small thin plates or discs; these stacks are about 0.9 μm in length and 0.06 μm in height. The mesocyst precursors are fibrillar bodies of variable shapes, about 2.4 μm in maximum length and 0.12–0.16 μm in diameter. These precursors appear in the cytoplasm of the precystic cell during the first precystic stage (stage A). The endocyst precursors are rounded bodies surrounded by a fine membrane, and their contents appeared similar to the endocyst. The granular layer precursors are spherical bodies about 0.1–0.2 μm in diameter, surrounded by a double membrane presenting ribosomes adhering to its outer membrane. Both endocyst and granular layer precursors are observed in the precystic cytoplasm from stage B. On the basis of ultrastructural studies, a formation and growth model of the cyst wall of the hypotrichous ciliate Laurentiella acuminata is proposed.
Characterization of Two Sibling Species of the Genus Stylonychia (Ciliata, Hypotricha): S. mytilus Ehrenberg, 1838 and S. lemnae n. sp. I. Morphology and Reproductive Behavior1
Authors: AMMERMANN DIETER , SCHLEGEL MARTIN
Published: May 2007

All Stylonychia mytilus‐like ciliates which were collected and sent to us during the last 20 years belonged either to S. mytilus or to a new species, S. lemnae, which is described here. The only morphological differences are the shape and the size. Stylonychia mytilus that have been starved for one day average 300 μm in length, and S. lemnae starved for a day are 230 μm long. The occurrence of mating types is described.
Ultrastructural Observations on the Infection of Rat Liver by Plasmodium berghei Sporozoites In Vivo1
Authors: MEIS JACQUES F. G. M. , VERHAVE JAN PETER , JAP PAUL H. K. , SINDEN ROBERT E. , MEUWISSEN JOSEPH H. E. T.
Published: May 2007

The invasion of liver parenchymal cells by sporozoites of Plasmodium berghei Vincke & Lips, 1948, was studied in vivo using transmission electron microscopy. Livers of Brown Norway rats were examined 30 and 60 min after intraportal injection of 15 million sporozoites each. Sporozoites found after incorporation into vacuoles in hepatocytes were often located near a bile canaliculus at the lateral cell surface, surrounded by hepatocyte lysosomal structures; however, degradation of sporozoites caused by lysosomal digestion inside hepatocytes was never observed. Due to the crescent shape of sporozoites, serial sections were necessary to demonstrate the actual process of invasion of the hepatocyte. The hepatocyte's plasmalemma appeared to invaginate due to the sporozoite's action, thereby creating a parasitophorous vacuole. It was suggested that the sporozoite actively penetrated the hepatocyte; however, no visible depletion of rhoptries and micronemes was observed.
Fine Structure and Cytochemistry of the Hydrogenosome of Tritrichomonas foetus1
Authors: BENCHIMOL MARLENE , SOUZA WANDERLEY DE
Published: May 2007

Fine structural studies of the hydrogenosomes of Tritrichomonas foetus using an improved fixative reveal that they are enclosed by two closely apposed 6 nm membranes, which separate at some regions forming a large intramembranous vacuole where Ca++‐binding sites are located. Fixation of the cells in a glutaraldehyde solution containing 5 mM CaCl2 and postfixation in an osmium tetroxide‐potassium ferrocyanide solution led to the appearance of a reaction product associated with certain regions of the membrane of the hydrogenosomes and in the cisternae of the endoplasmic reticulum, in the recurrent flagellum, and in the plasma membrane. Treatment of ultrathin sections with EGTA removed the reaction product. These results, in association with others previously described, indicate the existence of several similarities between the hydrogenosomes and the mitochondria.
Electron Microscopic Observations of the Bloodstream Form of Cryptobia salmositica Katz, 1951 (Kinetoplastida: Bodonina)1
Authors: PATERSON W. BROCKLEY , WOO PATRICK T. K.
Published: May 2007

The ultrastructure of the bloodstream form of Cryptobia salmositica in rainbow trout was examined during the acute phase of experimental infection. The arrangement of the major groupings of cytoplasmic microtubules originating near the basal bodies is similar to that in other bodonids. The cytostome is reinforced both by pellicular microtubules and an electron‐dense plaque. Certain microtubules associated with the flagellar pocket serve as nucleating sites for pellicular microtubules. A flagellar rootlet, consisting of two parallel fibers which are bound together intermittently by electron‐dense plaques, curves posteriorly from the basal body of the recurrent flagellum towards the kinetoplast. The basal body associated plaque on the kinetoplast membranes is duplicated at the same time as the basal bodies. Cytoplasmic microtubules are found in association with the plaque and the outer kinetoplastic membrane. A pulsatile vacuole, described for the first time in a hemoparasitic cryptobiid, lies adjacent to the post‐flagellar pit. Smaller, interconnected vesicles of the spongiome are continuous with the pulsatile vacuole. Since a pulsatile vacuole occurs not only in free‐living and ectoparasitic cryptobiids but in the hemoparasitic (=trypanoplasm) forms as well, this is no longer a character by which the genus Trypanoplasma may be separated from the genus Cryptobia. Possession of this osmoregulatory complex may allow the organism to survive outside of a host and fulfill a monoxenous life cycle, in addition to the usual heteroxenous cycle involving a leech as vector.
Transmission of Herpetomonas in Laboratory Populations of Drosophila melanogaster
Authors: ROWTON EDGAR D. , McGHEE R. BARCLAY
Published: May 2007

Methods of transmission and the effects of temperature and mites on ageledeme development of Herpetomonas were examined in populations of Drosophila melanogaster maintained in the laboratory. Herpetomonas was observed in feces of infected adults taken from population cages and in the vomitus of clean flies shortly after feeding on a saline suspension of flagellates. Free‐swimming flagellates were found in the moist areas of food cups. Adult D. melanogaster became infected when they fed on flagellates taken from the endoperitrophic space, the ectoperitrophic space or the Malpighian tubules.

At 25°C the flagellates infected approximately 90% of the host population within 20 days. The high transmission rate was prematurely disrupted if host populations were subjected to changes in temperature. Free‐swimming flagellates did not appear to be affected at these temperature changes. Food mites (Tyrophagus) established in the growth media of the fly nearly eliminated the Herpetomonas from Drosophila populations.
Staining of Plasmodium yoelii‐Infected Mouse Erythrocytes with the Fluorescent Dye Rhodamine 1231
Authors: TANABE KAZUYUKI
Published: May 2007

The cationic permeant fluorescent dye rhodamine 123 (R123) was used to stain Plasmodium yoelii‐infected mouse erythrocytes. Fluorescence microscopic observations demonstrated that the parasite, but not the matrix of the infected erythrocyte, accumulated the dye. Differences in fluorescence intensity could not be found at the various developmental stages of the parasite; however, quantitation of the cell‐associated dye revealed an increase in R123 uptake with parasite development. The retention of the parasite‐associated dye, as measured by fluorescence microscopy and spectrophotometry after extraction of R123 with butanol, was markedly reduced by treatment of the infected erythrocytes with a proton ionophore, carbonyl cyanide m‐chlorophenylhydrazone (CCCP), and an inhibitor of proton ATPase, dicyclohexylcarbodiimide (DCCD). These results indicate that the accumulation and retention of R123 in P. yoelii reflect the parasite membrane potential and suggest that the parasite plasma membrane has a membrane potential‐generating proton pump.
Multiple Fission in Allogromia sp., Strain NF (Foraminiferida): Release, Dispersal, and Ultrastructure of Offspring1
Authors: BOWSER SAMUEL S. , McGEE‐RUSSELL S. M. , RIEDER CONLY L.
Published: May 2007

The release, dispersal, and ultrastructure of juveniles arising through multiple fission in the benthic foraminiferan Allogromia sp., strain NF (Lee & Pierce, 1963) has been examined by light and electron microscopy. An extensive reticulopodial network participates in the dispersal of fully differentiated young as they emerge from the fragmented parental test. During the earliest stages of release, offspring are of two classes—aroused and unaroused. Unaroused juveniles, which have not extended pseudopods, attach externally to the network and are transported bidirectionally along its surface. Aroused juveniles, which have extended pseudopods and are in protoplasmic continuity with the network, move quickly to the periphery of the network. Within 24 h, juveniles establish a communal “feeding reticulum” in which dispersed individuals are in protoplasmic continuity with neighbors via a common reticulopodial network. At the ultrastructural level, the cell body cytoplasm of unaroused juveniles contains numerous patches of a paracrystalline material, which disappears as their pseudopodia are extended to join the communal feeding reticulum. This paracrystalline material therefore appears to be a temporary reservoir of precursors required for pseudopod construction.
In Vitro Studies on the Biosynthesis of the Surface Glycoprotein of Trypanosoma congolense1,2
Authors: REINWALD ERWIN , HEIDRICH CLAUDIA , RISSE HANS‐JÖRG
Published: May 2007

Tritiated leucine, glucosamine, mannose, and galactose were incorporated into the variant specific surface glycoprotein (VSG) of Trypanosoma congolense in vitro. The uptake of the precursors is shown by SDS‐polyacrylamide electrophoresis and fluorography, by assay of the radioactivity in immunoprecipitates obtained with specific antisera, and by the isolation of the labeled antigens by affinity chromatography on concanavalin A‐sepharose and isoelectric focusing. The in vitro labeled VSG exhibits the same degree of microheterogeneity as that observed in the VSG isolated from trypanosomes grown in animals. Analysis of the incorporated sugars after hydrolysis of the glycoprotein showed that glucosamine and mannose were utilized in biosynthesis of the carbohydrate moiety directly whereas galactose was converted possibly to other intermediates before being incorporated into the antigen. Tunicamycin completely prevented the incorporation of the radiolabeled sugars into the surface glycoprotein. The unglycosylated VSG with a molecular weight of 47 kDa had completely lost its size heterogeneity.
Lepidotrachelophyllum fornicis, n. g., n. sp., a Ciliate with an External Layer of Organic Scales (Ciliophora, Litostomatea, Haptoria)1
Authors: NICHOLLS K. H. , LYNN DENIS H.
Published: May 2007

Lepidotrachelophyllum fornicis n. g., n. sp. was discovered in White Lake, Ontario, Canada, under winter ice. The genus is Trachelophyllum‐like, being highly flattened, elongate, and very extensible. The major feature that separates it from other genera in the family Trachelophyllidae is the presence of a dense layer of organic scales which covers the exterior of the cell and through which the cilia emerge. The scales are composed of filamentous material which is organized as an ovoid structure. The “rim” of the baseplate is formed of interwoven filaments. The baseplate is broken by circular or polygonal apertures. The same filaments form an arched superstructure broken by even larger, less regular apertures.
Trypanosoma lucknowi, a New Species of Trypanosome from Macaca mulatta with Observations on Its Fine Structure1
Authors: WEINMAN DAVID , WHITE ELIZABETH ANN , ANTIPA GREGORY A.
Published: May 2007

Trypanosoma lucknowi n. sp. was isolated in culture from one of 126 Macaca mulatta originating from the vicinity of Lucknow, Uttar Pradesh, India. Trypanosoma lucknowi is distinctive because of the large number of epimastigotes and trypomastigotes which, in culture, exhibit no movement or only a slight bending of the flagellar end. This limited motility coincides with a free flagellum which is either completely absent or rudimentary. The microorganism is cloned readily, and the description is based upon such cultures. Trypanosoma lucknowi shows pronounced differences from other trypanosomes of South Asian macaques and from “aflagellar” African trypanosomes. The ultrastructural demonstration of a cytostome and contractile vacuole suggests ultimate grouping with stercorarian trypanosomes. A 3‐D reconstruction of the flagellar pocket/cytostome region is included.
Effects of Mitochondrial Protein Synthesis Inhibitors on the Incorporation of Isoleucine into Plasmodium falciparum In Vitro1
Authors: BLUM J. J. , YAYON A. , FRIEDMAN S. , GINSBURG H.
Published: May 2007

Plasmodium falciparum was grown in human erythrocytes in vitro and the effect of chloramphenicol, erythromycin, and tetracycline on growth and maturation of the parasites and on their ability to incorporate [3H]isoleucine into protein was observed. Exposure of rings to high concentrations of chloramphenicol had little effect on subsequent maturation of the rings whereas brief (4 h) exposure of trophozoites caused a dose‐dependent inhibition of subsequent ring formation. Incorporation of [3H]isoleucine into protein was not affected during at least 6 h of exposure to high concentration of the three drugs examined, but appreciable inhibition was observed after 21 h, with chloramphenicol being the least effective inhibitor. These results suggest that there is a stage‐specific effect of inhibition of mitochondrial protein synthesis on subsequent development and that the mitochondria are essential for growth and development even though they lack a functional Krebs cycle.
Localizing Surface‐Related Proteins in Ciliates by Indirect Immunofluorescence Microscopy1
Authors: WILLIAMS NORMAN E.
Published: May 2007

Results obtained in immunofluorescence localization studies involving three antisera, six species of ciliates, and a variety of fixation procedures suggest that superior results can often be obtained by fixing cells in 35–70% ethanol. Formaldehyde fixation appeared to induce redistributions of epiplasmic proteins and surface antigens which were not observed in ethanol‐fixed cells. In addition, background fluorescence was significantly lower in ethanol‐fixed cells than it was in cells fixed in aldehydes.
Paramecium Phagosome Membrane: From Oral Region to Cytoproct and Back Again1
Authors: ALLEN RICHARD D.
Published: May 2007

Ten years of research on digestive vacuoles (phagosomes) of Paramecium caudatum have revealed sequential changes both within the vacuole lumen as well as within the surrounding membrane. Four vacuole stages can be recognized by a combination of thin section and freeze‐fracture ultrastructural features. Three sets of vesicles (discoidal vesicles, acidosomes, and lysosomes) fuse with the vacuole, each at a predetermined stage, to bring about these membrane and physiological changes. At various times membrane is removed as vesicles from the vacuole surface, which has the effect of regulating vacuole size. Membrane recycling, membrane replacement, and specific membrane to membrane recognition all appear to be operating during the digestive cycle. Details of these events are summarized in this address and a number of unanswered questions suggest areas for future research.
Two New Species of Myxozoa, Myxobolus inaequus sp. n. and Henneguya theca sp. n. from the Brain of a South American Knife Fish, Eigemannia virescens (V.)
Authors: KENT MICHAEL L. , HOFFMAN GLENN L.
Published: May 2007

Two new species of Myxozoa from the brain of the green knife fish Eigemannia virescens are described: Myxobolus inaequus sp. n. has an unusually large spore body and extremely unequal polar capsules, and Henneguya theca sp. n. has an attenuated spore encased in a sheath not previously described in other Myxozoa. Only spores of the two species were observed, and infections caused no obvious pathological changes in the brain.
Membrane Protein Differences Correlated with the Development of Mating Competence in Tetrahymena thermophila1
Authors: BELL CRAIG T. VAN , WILLIAMS NORMAN E.
Published: May 2007

Initiation is the contact‐independent phase of sexual conjugation which occurs when mature cells of Tetrahymena thermophila are shifted from growth medium to a low‐salt starvation buffer. Immaturity, like high‐salt starvation, restricts the ability of cells to conjugate; immature cells do not conjugate in either low‐ or high‐salt buffers. Comparisons between sexually mature cells starved in initiation‐restrictive and initiation‐permissive buffers, and between immature and mature cells starved in an initiation‐permissive buffer permitted the analysis of membrane protein expression correlated with mating competence. No polypeptides identified by lactoperoxidase‐catalyzed iodination were found to be specific to mating‐competent cells; however, several polypeptides not present in initiated cells were found to be common to the cell surfaces of immature and non‐initiated cells which suggests that (1) initiation involves the removal of specific proteins from the cell surface, and (2) immaturity may be due to an inability to initiate.
Enzymes of Carbohydrate Metabolism in Leishmania donovani Amastigotes1
Authors: MEADE JOHN C. , GLASER THERESA A. , BONVENTRE PETER F. , MUKKADA ANTONY J.
Published: May 2007

A method for the isolation of Leishmania donovani amastigotes from infected hamster spleen and liver tissues is described. Over 85% of the isolated amastigotes were viable as judged by acridine orange‐ethidium bromide staining and in vitro transformation to the promastigote form. A comprehensive survey of the enzymes of carbohydrate metabolism in L. donovani amastigotes and promastigotes was conducted. Amastigotes and promastigotes possess all of the enzymes of the Embden‐Meyerhof pathway, hexose monophosphate shunt, and tricarboxylic acid cycle. Cell‐free extracts of both forms show pyruvate dehydrogenase activity which permits entry of pyruvate into the tricarboxylic acid cycle. Both forms demonstrate an active glutamate dehydrogenase, thus linking amino acid metabolism with carbohydrate metabolism. Pyruvate carboxylase, the enzyme responsible for replenishment of C4 acids by heterotrophic CO2 fixation into pyruvate, was also demonstrable in the tissue and insect forms. In general, activities of promastigote enzymes are higher than the amastigote enzymes. Differences between the vertebrate (amastigote) and invertebrate (promastigote) forms in their potential to utilize carbohydrates as substrates would appear to be quantitative rather than qualitative.
Fine Structural Alterations in Trypanosoma rhodesiense Grown In Vitro, Treated with WR 1635771
Authors: BERMAN J. D. , OKA M. , AIKAWA M.
Published: May 2007

Fine‐structural alterations in Trypanosoma rhodesiense trypomastigotes exposed to WR 163577, a prophylactic agent against animal African trypanosomiasis, were determined from cells grown in vitro. Exposure of trypomastigotes to a low concentration of drug resulted only in condensation of kinetoplast DNA fibrils. Exposure to higher drug concentrations caused clumping of nuclear chromatin and of cytoplasmic contents. Although alteration of kinetoplast DNA is the first detectable drug‐induced change, the function of the kinetoplast in mammalian forms of African trypanosomes is unclear, and the secondary changes in the nucleus and cytoplasm may constitute the functionally significant alterations caused by WR 163577.
Description of Sarcocystis falcatula Stiles, 1893, a Parasite of Birds and Opossums1
Authors: BOX EDITH D. , MEIER JUDY L. , SMITH JEROME H.
Published: May 2007

ABSTRACT. Sarcocystis falcatula Stiles, 1893 is re‐described. Intermediate hosts of the parasite which was earlier described as Sarcocystis debonei Vogelsang, 1929 are species of passeriform, psittaciform, and columbiform birds. In these birds, muscle zoites are 6.88 × 2.19 (4.8‐8.4 × 1.2‐3.6) μm and are enclosed in a cyst wall with regular protrusions, 1‐5 μm long. The convoluted primary wall has multiple thin areas in the osmiophilic layer. Microtubules originate in the ground substance and extend to the tips of the protrusions. The only known definitive host is the opossum, Didelphis virginiana; rats, cats, a dog, and a ferret could not be infected from muscle cysts. Sporocysts from opossums infected from five different infected avian sources measure 11.2 × 7.4 (9.6−12.0 × 6.0‐8.4)μm.
Some Parasitic Protozoa from the Gambia
Authors: BRAY R. S.
Published: May 2007

ABSTRACT. A new species of Eimeria from the fat‐tailed gecko Hemidactylus brookei in Gambia, West Africa, was described and named E. helenae in honor of Mrs. Helen Levine. The oocysts averaged 22.2 μm and each contained four sporocysts (8.0 × 6.9 μm) with two sporozoites per sporocyst. No schizogony or gametogony was discovered in the intestine, suggesting that these stages may occur in the liver or bile cannuli. The oocysts of an adeleid parasite of the insect prey of the centipede Scolopendrium morsitans were described. Plasmodium agamae, an eimeriid hemogregarine, Pirhaemocyton, and a Shellackia‐type parasite were found in the blood of agamid lizards. The fruit bat Epomorphorus gambianus was commonly and heavily infected with Hepatocystis epomorphori.
Etude ultrastructurale comparée du processus de dégradation de l'hémoglobine par P. berghei (Vincke et Lips, 1948) en fonction de l'état de maturité de la cellule hǒte1
Authors: Slomianny C. , Prensier G. , Charet P.
Published: May 2007

By serial sectioning and 3D reconstruction we have been able to demonstrate that the type of system for hemoglobin digestion in two strains of Plasmodium berghei, N and RC, is dependent on the maturity of the host cell. In parasites growing in erythrocytes, both systems for the endocytosis of hemoglobin—micropinocytosis and the cytostomal system (i.e. a cytostome budding a cytostomal tube that releases food vacuoles)—are fully functional and produce a great quantity of residual pigment. Parasites growing in reticulocytes have a disrupted cytostomal system; no tube is formed and only food vacuoles are visible in their cytoplasm. Residual pigment is smaller in size and in quantity. The reduced quantity of pigment in reticulocytes is explained by our observation of the exocytosis of pigment. We propose a hypothesis that relates the process of degradation of hemoglobin to the maturity of the host cell and a possible mechanism of protection against chloroquine, a drug known for its affinity for malarial pigment.
S‐Adenosylhomocysteine Hydrolase Deficiency in Cysteine Auxotrophs of Tetrahymena thermophila1
Authors: Murphy Sharon E. , Fall Ray
Published: May 2007

The biochemical lesion in two cysteine auxotrophs of Tetrahymena thermophila has been established as a defect in S‐adenosylhomocysteine hydrolase, an enzyme of the transsulfuration pathway. As a result, these mutants require cysteine (or cystathionine or homocysteine) for growth in a denned medium. Cell‐free extracts of the mutants contained < 5% of the level of the enzyme seen in the wild type. One of the mutant strains accumulated intracellular levels of S‐adenosylhomocysteine as high as 1380 üM, a level 200 times normal. When both mutant strains were maintained in defined medium without cysteine, growth occurred after a long lag; this phenomenon was termed “adaptation.” Adaptation was a) reversed by passage through rich medium, b) was not a recovery of S‐adenosylhomocysteine hydrolase, and c) was probably linked to induction of an alternate pathway for cysteine biosynthesis, involving a lysosomal S‐adenosylhomocysteine nucleosidase activity.
Purification of Tissue Forms (Amastigotes) of Trypanosoma cruzi by Immunoaffinity Chromatography1
Authors: Campos‐Neto Antonio , Lima Fernanda W. M. , Andrade Arnaldo F. B.
Published: May 2007

A rapid and simple method for the purification of amastigotes of Trypanosoma cruzi from spleens of infected mice is described. A protein A‐Scpharose 4B immunoadsorbent column bound with antisera to epimastigotes of T. cruzi was used to purify the tissue forms of this parasite. Host cells and debris are not retained, and parasites can be eluted in high yields and purity. Studies of surface glycoproteins and glycolipids of the purified amastigotes with 18 lectins of various specificities revealed the presence on the parasites of receptors for N‐acetylglucosamine, N‐acetylgalactosamine, D‐galactose, and D‐mannose binding lectins.
An in Vitro Assay for Sequestration: Binding of Plasmodium falciparum‐Infected Erythrocytes to Formalin‐Fixed Endothelial Cells and Amelanotic Melanoma Cells1
Authors: Udeinya Iroka J. , Leech James , Aikawa Masamichi , Miller Louis H.
Published: May 2007

Erythrocytes infected with Plasmodium falciparum bind specifically to cultured endothelial cells and to a line of amelanotic melanoma cells. We have fixed endothelial cells and amelanotic melanoma cells in various ways and determined whether the fixed cells were still able to bind infected erythrocytes. Only cells fixed with 1.0‐2.5% formalin in phosphate‐buffered saline continued to bind infected erythrocytes as well as unfixed cells. The mechanism of binding to fixed and unfixed cells appeared to be identical for the following reasons. First, erythrocytes infected by parasite strains that bound to unfixed cells also bound to fixed cells while those that did not bind to unfixed cells did not bind to fixed cells. Second, immune serum that inhibited binding to unfixed cells also inhibited binding to fixed cells. Third, electron microscopy showed that knobs were the points of attachment between infected erythrocytes and both fixed and unfixed melanoma cells. Fixed cells gave reproducible results over at least 2 months. Thus, we have developed a simplified, reproducible assay for measuring binding of P. falciparum‐infected erythrocytes to target cells.
Vertical Distribution of Potentially Pathogenic Free‐Living Amoebae in Freshwater Lakes1
Authors: Kyle Dennis E. , Noblet Gayle Pittman
Published: May 2007

The vertical distribution of thermotolerant (37°C and 45°C) free‐living amoebae (FLA) in warm monomictic lakes was determined in relation to the onset of thermal stratification and associated physical and chemical changes. The position of abiotic or biotic paniculate layers in the water column was located by using a submersible horizontal beam transmissometer that measures attenuance, or the absorption and scattering of light by participates in the water column. During mixis, the vertical distribution of amoebae was sporadic with significant numbers of FLA only occurring in clay layers caused by runoff after heavy rains. With the onset of thermal stratification in the lakes, phytoplankton layers began to form. Few amoebae were isolated from layers containing flagellated phytoplankton; however, significant (P < 0.005) numbers of FLA were isolated from two paniculate layers dominated by the filamentous blue‐green algae Aphanizomenon and Lyngbya, respectively. By late June, a persistent detrital or decomposition layer formed in the lower metalimnion, as well as a hypolimnetic iron layer where the Fe2+ state was predominant. In this midsummer period, 13 Naegieria fowleri were isolated, with three from the detrital layer and seven from the iron layer. The presence of attenuation zones was found to be the best indicator of the vertical distribution of FLA in the water column, and such layers represent an important, previously undescribed habitat for potentially pathogenic FLA.
Cytopathogenicity of Naegleria fowled for Cultured Rat Neuroblastoma Cells1
Authors: Fulford D. E. , Bradley S. G. , Marciano‐Cabral F.
Published: May 2007

The cytopathogenicity of Naegleria fowleri strain LEE (ATCC‐30894) for cultured rat neuroblastoma cells (B‐103) has been investigated. Both live N. fowleri amoebae and Naegleria lysates added to 51Cr‐labeled B‐103 cells caused release of radiolabel, which was dependent upon the ratio of amoebae to target cells or to the lysate concentration. Lysates of N. fowleri strains LEE, NF‐66, NF‐69, and HB‐4 were equally injurious to B‐103 target cells whereas lysates of strains 6088 and KUL were less cytotoxic. Highly pathogenic mouse‐passaged strain LEE were less cytotoxic than axenically grown amoebae. Maximum cytotoxicity was observed in lysates from amoebae in late exponential or early stationary phase of growth. Cytopathogenicity of lysates was reduced after heating at 44°C for 60 min or at 60°C for 30 min. Cytotoxicity was stable during storage at 4°C or at −20°C for 26 h. Neither live amoebae nor lysates injured B‐103 target cells at 4°C. Live amoebae and lysates injured B‐103 by a time, temperature, and concentration dependent process.
Cryptolembus gongi n. gen., n. sp., a Philasterine Scuticociiiate from the Intestine of the Tunicate Ascidia ceratodes (Huntsman, 1912)1
Authors: Gunderson John
Published: May 2007

A philasterine scuticociiiate 82‐133 μm in length and 29‐51 μm in width is described from the intestine of the solitary tunicate Ascidia ceratodes. It has 44 somatic kineties, an anterior dorsal bald spot, and a triangular scutico‐vestige which lies above recessed posterior oral polykinetids.
Coccidia in Camels (Camelus dromedarius) in Saudi Arabia1
Authors: Kasim Ahmed A. , Hussein Hussen S. , Shawa Yaser R. Al
Published: May 2007

Saudi Arabian camels {Camelus dromedarius) are infected with three species of Eimeria: E. dromedarii (28.4%), E. rajasthani < 22.2%), and E. cameli (19.2%); 41.6% of the animals examined were positive. The highest prevalence of infection was reported in the western region of the country. Mixed infection with two Eimeria species is most common; E. dromedarii was most frequently and generally the most predominant species. Eimeria dromedarii and E. rajasthani are described for the first time from Saudi Arabian camels.
Fluorescein‐Conjugated Folate as an Indicator of Specific Folate Binding to Paramecium1
Authors: VAN HOUTEN J. L. , SMITH R. , WYMER J. , PALMER B. , DENARO M.
Published: May 2007

Normal Paramecium tetraurelia cells stained with fluorescein‐conjugated folate show intense fluorescence that can be reduced to near background autofluorescence with excess K2‐folate, but not with excess KCl. Mutant d4–534, which is not attracted to folate and does not specifically bind 3H‐folate, shows reduced fluorescence when stained. This method of monitoring specific folate binding to cells can be adapted to a microscale for rapid screening of clones since cells are routinely fixed and stained in microtiter wells.
Subcellular Distribution of Hydrolases in Naegleria fowleri1
Authors: DAVID M. LOWREY  , JOHN McLAUGHLIN
Published: May 2007

The presence and particle association of various hydrolytic enzymes in Naegleria fowleri has been studied in whole cell extracts of trophozoites in an effort to establish authentic markers for surface membrane and lysosomal components. Evidence from the experiments reported here indicates that in N. fowleri a) acid proteinase, N‐acetylglucosaminidase, and acid phosphatase are associated with cytoplasmic granules closely resembling lysosomes; b) 5'‐nucleotidase is associated with the surface membrane, probably on the external surface; c) aspartate aminotransferase is associated with mitochondria; d) a‐D‐glucosidase and an aminopeptidase have bimodal distributions, activity being associated with both the surface membrane and lysosomal particles.
Enzyme Variation in Paramecium caudatum
Authors: KHADEM N. , GIBSON I.
Published: May 2007

Stocks of four “syngens” (syngens 1, 3, 12, 13) of Paramecium caudatum could not be distinguished on the basis of isozymic variations of six enzymes. Using the most common enzyme form as the standard for the syngen, we found a higher coefficient of identity between syngens (>90%) than within syngens (73%). These observations, combined with evidence for fertile matings among the groups, suggest that the groups do not warrant the status of syngens. True syngenic variation in P. caudatum is, however, clearly established on the basis of isozymic and breeding studies of wild stocks collected from various places. Some stocks from England have a close affinity with those from Japan, but stocks from Scotland and California must be placed in separate syngenic sets. Thus, P. caudatum is indeed a species complex, within which evolutionarily distinct groups (species = syngens) are identifiable. The definition of syngens on the basis of initial agglutination response is, however, unjustified.
Action of the Organophosphorous Insecticide Parathion on the Free‐Living Marine Dinoflagellate Prorocentrum micans Ehrbg.
Authors: PREVOT P. , SOYER M.‐O.
Published: May 2007

Growth of cultures of the dinoflagellate Prorocentrum micans Ehrbg. was slowed by parathion >1 ppm. Parathion also decreased chlorophyll content and perturbed cellular ultrastructure, eliciting especially plastoglobuli in their chloroplasts. Toxicity of this organophosphorous insecticide is unlikely to be due to its anticholinesterase activity since P. micans appears not to contain cholinesterase. Fluorescence kinetics show that parathion affects the photosynthetic system, particularly photosystem II.
Flagellar Morphology in Stumpy‐Flagella Mutants of Chlamydomonas reinhardtii1
Authors: JARVIK JONATHAN W. , CHOJNACKI BONNIE
Published: May 2007

Sixteen new mutants of the biflagellate green alga Chlamydomonas reinhardtii with either stumpy‐flagella or no flagella at all were examined by electron microscopy. Four of the mutants were found to carry short bulbous flagella containing amorphous electron‐dense material which may represent unassembled flagellar protein. Basal bodies of normal ultrastructure were present in all mutants. Dikaryon dominance tests indicated that the stumpy mutations were recessive to wild‐type in all cases tested. Stumpy mutations also conferred a measure of detergent resistance to Chlamydomonas, apparently by affecting the detergent‐solubility of the flagellar membrane.
Cytolytic Activity Released from Tetrahymena1
Authors: FLORIN‐CHRISTENSEN J. , FLORIN‐CHRISTENSEN M. , KNUDSEN J. , RASMUSSEN L.
Published: May 2007

Using a hemolytic assay system, we have detected cytolytic activities in extracellular medium from Tetrahymena thermophila and T. pyriformis. In addition, we have identified two phospholipase activities (types A and C) from the same source by thin layer chromatography analysis of the breakdown products of a phospholipid preparation. The hemolytic activity peaks at low pH values. It is inhibited by egg lecithin, supporting the view that a phospholipase activity is involved in the cytolytic processes. Cytolytic activities may play important roles in Tetrahymena, both in nutrition, especially in parasitic and scavenger forms, and in defense against predators. Tetrahymena is probably partly protected from its own released cytolytic phospholipase by having a high proportion of phosphonolipids on its surface membrane.
Phagocytic Activity of Three Naegleria Strains in the Presence of Erythrocytes of Various Types1
Authors: ALONSO PILAR , ZUBIAUR ELENA
Published: May 2007

The phagocytic activities of N. lovaniensis (Aq/9/1/45D) and N. gruberi (1518/1f and 1518/1e) were studied in the presence of erythrocytes of various species: chicken, rabbit, goat, and human (A+, B+, and AB+ were tested). The percentage of amoebae with ingested red cells, the phagocytic index (PhI), can be considered as an expression of phagocytic activity. Under given conditions (erythrocyte concentration, incubation time, age of amoebic cultures) each strain of Naegleria prefers one erythrocyte type. Thus, for 72‐h cultures, N. lovaniensis ingested more A+ type erythrocytes than did N. gruberi strains but had very low affinity for rabbit red cells except when very high concentrations were tested. Naegleria gruberi 1f was the most active of the three strains towards rabbit and B+ and AB+ human erythrocytes, but very low PhIs were obtained with goat erythrocytes. Naegleria gruberi le exhibited high phagocytic activity for every erythrocyte type except for rabbit red cells.
Fine Structure of Exoerythrocytic Merozoite Formation of Plasmodium berghei in Rat Liver1
Authors: MEIS JACQUES F. G. M. , VERHAVE JAN PETER , JAP PAUL H. K. , MEUWISSEN JOSEPH H. E. T.
Published: May 2007

The fine structure of exoerythrocytic merogony of Plasmodium berghei was studied after perfusion‐fixation of rat livers from 51 h post‐inoculation onwards. Meroblast formation was effected by clefts originating from the parasite plasmalemma and by fusion of vacuoles with each other. Invaginations at the periphery resulted in labyrinthine structures providing the parasites with an enormous increase in surface area, which might facilitate exchange of metabolites. When the parasitophorous vacuole membrane collapsed, the newly formed merozoites were lying free in the hepatocytic cytoplasm, which degenerated until the merozoites were sticking together by a stroma, obviously a remnant of the host hepatocyte. Groups of merozoites, still kept together by the spongy stroma, were subsequently released in the bloodstream. At 53 h most of the developmental stages leading to the release of merozoites could be found and thereafter parasite numbers decreased while large granulomas became apparent.
Population Growth in Stationary and Suspension Culture of Paramoeba pemaquidensis Page (Amoebida, Paramoebidae)1
Authors: MARTIN RONALD E.
Published: May 2007

Paramoeba pemaquidensis Page requires attachment to a substrate in order for population growth to occur. Populations of amoebae suspended in bacterized culture media on a roller tube apparatus did not increase in size whereas amoebae maintained in stationary control tubes multiplied in number. Amoebae maintained in suspension for as long as three weeks attached and multiplied in culture when allowed to settle. This suggests that Paramoeba found suspended in the surface microlayer of the ocean may be in a “dormant” state. Implications for the survival and geographic distribution of the genus are discussed.
Concept, Definition, Prevalence, and Host‐Interactions of Xenosomes (Cytoplasmic and Nuclear Endosymbionts)1,2
Authors: CORLISS JOHN O.
Published: May 2007

ABSTRACT.

In this paper the concept of “xenosome” is greatly expanded from its current usage, which has been based on its application during the past 10 years by Soldo and co‐workers solely to certain bacterial invaders of the cytoplasm in species of a single genus of marine scuticociliales. The author proposes that the term now be considered to embrace all DNA‐containing, membrane‐bounded bodies or organelles—prokaryotic or eukaryotic in original nature—found within the cytoplasm or nucleus of eukaryotic cells of any or all kinds, whether the occupation (“colonization”) is temporary and transient or permanent and stable. Thus, virulent or pathogenically infectious organisms can be included as well as the commonly recognized cell endosymbionts sensu stricto, which are often mutualistic in nature. Of significance, such “normal” cell organelles as plastids, mitochondria, and even nuclei may also be embraced by this expanded definition of xenosome, based on the conjecture that these inclusions might have been “alien” or “foreign” extracellular, independent, free‐living organisms in their own past evolutionary histories. The author's enlarged concept and unifying principle allows more meaningful comparative consideration of the numerous and diverse kinds of xenosome‐host interrelationships, many of which involve species of protozoa and algae from a large number of the taxonomic groups comprising the kingdom Protista.
Feeding Behavior in the Ciliate Pseudomicrothorax dubius is a Series of Morphologically and Physiologically Distinct Events1
Authors: PECK ROBERT K.
Published: May 2007

Based upon light and electron microscopical observations, the feeding behavior of the ciliate Pseudomicrothorax dubius, when fed the cyanobacterium Oscilatoria formosa, is resolved into two principal phases, contact swimming and phagocytosis, the latter being separable into two steps, attachment aad ingestion. Following collision with an O. formosa filament. cells swim along the filament with their ventral cilia in contact with it during the contact swimming phase. Phagocytosis commences with the attachment of the cytostome to the filament, which initiates lysosomal streaming in the cytostomal‐cytopharyngeal region. The filament then enters the cytopharynx concomitant with food vacuole formation during the ingestion step. Treatment of cells with trypsin or modification of the extracellular ionic medium inhibits the attachment step of phagocytosis but does not affect contact swimming. Behavior of cells when fed different cyanobacterial species as well as artificial food substrates is also examined. Contact swimming is a form of contact guidance since the shape of the food substrate determines the direction of cell movement. Additionally, a chemical factor may be present in or on the cyanobacteria and play a role in contact swimming. Evidence is presented that suggests that during the attachment step, two phenomena are involved: direct adhesion between cell surfaces and adhesion due to material liberated by exocytosis.
An Organofluorophosphate‐Hydrolyzing Activity in Tetrahymena thermophila1
Authors: LANDIS WAYNE G. , SAVAGE RUSSELL E. , HOSKIN FRANCIS C. G.
Published: May 2007

An enzymatic activity that hydrolyzes O,O‐diisopropylphosphofluoridate (DFP) and O‐1,2,2–trimethylpropylmethyl‐phosphonofluoridate (Soman) was discovered in the ciliate protozoan Tetrahymena thermophila. The enzymatic activity classifies the protein as Mazur‐type similar to that found in hog kidney and Escherichia coli. The rate of hydrolysis of Soman by the Tetrahymena‐extract is the highest, on a per gram of extract basis, of any eucaryote. The molecular weight is approximately 75,400 as determined by Sephacryl column chromatography. A maximum fifteen‐fold purification has been achieved.

Potential exists for the detoxification and one‐step detection of common organofluorophosphate pollutants. Additionally, Tetrahymena should prove an easier subject for manipulation than mammalian or squid sources. Protozoa may be a potentially important source of detoxification and degradation enzymes for other environmental contaminants.