bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies of Blastocystis hominis
Authors: ZIERDT CHARLES H. 
Published: May 2007

SYNOPSISBlastocystis hominis, grown in Boeck‐Drbohlav culture medium, modified by the omission of rice starch and the addition of 20% human serum and mineral oil cover to the Locke's solution overlay, can assume 3 morphologic forms. In the absence of human serum the vacuolated form, which divides by binary fission predominates. In medium with high serum content the granular form appears, with 3 types of granules. Spheroid or more elongate cytoplasmic granules predominate. In older organisms, lipid granules are found either in the peripheral cytoplasm or in the central vacuolar space. In occasional cells, variable numbers of reproductive granules develop in the central vacuolar space. These latter granules are released from the organism and give rise to typical B. hominis cells. The 3rd form, the ameba form, appears in small numbers in older cultures and in those treated with antibiotics. Ameba forms feed on bacteria and have slow pseudopodial activity. Exposure to oxygen causes rapid damage to cell membrane, with resulting leakage and collapse.
Inhibition of Protein Synthesis: A Mechanism of Amebicide Action of Emetine and Other Structurally Related Compounds*
Authors: ENTNER NATHAN , GROLLMAN ARTHUR P. 
Published: May 2007

SYNOPSISNew amebicides usually have been discovered by empirical screening procedures while other drugs, such as emetine, were adopted after their clinical efficacy was demonstrated. Emetine, puromycin, and cycloheximide are amebicides recently shown to act as inhibitors of protein synthesis in animal cells; the present study was designed to determine the general relationship of this mode of action to amebicidal activity. Our results indicate that amebicides structurally related to emetine inhibit protein synthesis in Entamoeba histolytica. It seems likely that the lethality of many amebicides may be attributed to specific effects on macromolecular synthesis in E. histolytica.
The Fine Structure of Four “Species” of Amoeba*
Authors: FLICKINGER CHARLES J. 
Published: May 2007

SYNOPSISThe fine structure of Amoeba discoides, Amoeba dubia, and Amoeba amazonas was studied and compared with that of Amoeba proteus. The different kinds of amebas showed general similarities but differed in the ultrastructural details of their organelles. With respect to fine structure, A. discoides was indistinguishable from A. proteus, while both A. dubia and A. amazonas had distinctive features. The nuclei of all had a prominent honeycomb‐like fibrous lamina, but A. dubia differed from the others in the distribution of nucleoli within the nucleus. The mitochondria of A. amazonas were unusual in having a variable pattern of cristae, some being plate‐like and others tubular. Golgi bodies in A. amazonas had a greater proportion of vesicles and a smaller number of cisternae than those of the others, while Golgi bodies in A. dubia had highly flattened cisternae without a lining of filamentous material such as is found in the other types. The plasma membrane of A. dubia also lacked the prominent filamentous cell coat common to A. proteus and other amebas. The relation between the Golgi apparatus and the cell coat and the significance of the degree of development of the cell coat for pinocytosis and other phenomena is considered. The experimental use of these cells, including the formation of hybrids by nuclear transplantation is discussed.
Mechanism of Photoaccumulation in Paramecium bursaria
Authors: SAJI M. , OOSAWA F. 
Published: May 2007

SYNOPSISResponses of Paramecium bursaria to light intensity changes were investigated. The resting paramecia show a direction changing response (photophobic response) to a sudden decrease of light intensity, whereas no response was shown to an increase in intensity. The critical intensity decrease dIc necessary to show the response was measured at various values of initial light intensity, and the ratio dIc/I was found to be equal to ∼0.15. The swimming paramecia show different behavior depending on their swimming direction in the spatial gradient of light intensity. Paramecia show direction change more frequently when they are swimming down the gradient than in the opposite direction. This difference in the rate of direction changing is 13–17%. These results may offer an explanation for the mechanism of photoaccumulation.
Ultrastructure of Symbiotic Bacteria in Normal and Antibiotic‐Treated Blastocrithidia culicis and Crithidia oncopelti*
Authors: CHANG K.‐P. 
Published: May 2007

SYNOPSIS. An electron microscope study of diplosomes in Blastocrithidia culicis and bipolar bodies in Crithidia oncopelti has shown that both entities appear to be intracellular symbiotes and have a similar fine structure. They are enclosed by 2 unit membranes which are separated by a large space of very low density. The outer membrane is derived probably from the host cell. The matrix of the symbiotes is composed of dense ribosome‐like particles and of areas of low density containing fine fibrillae. The particles are of the same size as ribosomes in bacteria and the fibrils have the characteristics of bacterial DNA. Thus, the lucid areas with fibrillae correspond to the nucleoids in bacteria. These observations suggest that the symbiotes are bacteria.The effect of chloramphenicol (CAP) and penicillin G (PCL) on these symbiotic bacteria was studied by culturing the host flagellates in media containing the antibiotics. The effect was analyzed at different intervals after the treatment by electron microscopy. After single treatment in the blood broth containing 0.08% (w/v) CAP, symbiotes appeared to have enlarged nucleoids, became deformed and eventually degenerated. In Grace's medium (supplemented with 10% fetal bovine serum) containing 0.6 or 2.4% (w/v) PCL, symbiotes of C. oncopelti remained unaltered, whereas some symbiotes of B. culicis became pleomorphic. Symbiotes of both species persisted after repeated transfers in PCL media and reverted to normal forms when transferred to PCL‐free media. Sensitivity of symbiotes to CAP provides further evidence of their bacterial nature. The effect of PCL on the symbiotes of B. culicis suggests the presence in their cell envelopes of mucopeptide, which probably provides rigidity for maintaining the bacterial shape of the symbiotes.
La Genèse des Mérozoïtes chez la Coccidie Eimeria necatrix. Etude Ultrastructurale*
Authors: DUBREMETZ JEAN FRANCOIS 
Published: May 2007

RESUME. Les schizontes de 2 ème génération d'Eimeria necatrix ont étéétudiés au microscope électronique. La différenciation des mérozoïtes est associée à la dernière mitose, qui ne semble pas différer essentiellement des précédentes. Les mérozoïtes se développent à la périphérie du schizonte. Le conoide et 22 microtubules sous pelliculaires, probablement induits par les centrioles, et le complexe membranaire interne ainsi que les précurseurs des rhoptries, qui semblent issus de l'appareil de Golgi, apparaissent auprès de chaque pôle nucléaire, sous la membrane du schizonte. Ces organites sont les premiers inclus dans les ébauches de mérozoïtes. Puis, le noyau, le dictyosome et les vésicules multimembranaires pénètrent dans les futurs mérozoïtes. Les micronèmes, probablement formés par l'appareil de Golgi, et les grains d'amylopectine sont produits plus tard, quand les mérozoïtes se séparent du reliquat cytoplasmique. Le mode de genèse de ces divers organites et les relations entre le dernière mitose et la différenciation sont discutés.SYNOPSIS. Second generation schizonts of Eimeria necatrix were studied with the aid of the electron microscope. Differentiation of daughter merozoites is associated with the last mitosis, which is not significantly different from the earlier ones. The merozoites develop at the periphery of the schizont. The conoid and 22 subpellicular microtubules, probably induced by centrioles, and the inner membranes complex and the rhoptry anlagen which seem to be produced by the Golgi apparatus, appear close to each nuclear pole, just near the schizont membrane. These organelles are the first to appear in the merozoite anlagen. Then, nucleus, dictyosome and multimembranous vesicles enter the budding merozoites. Micronemes, probably originating from Golgi apparatus, and amylopectin granules are produced later, when daughter merozoites separate from the residuum. The genesis of these various organelles and the relation between the last mitosis and differentiation are discussed.
Omikron, ein essentieller Endosymbiont von Euplotes aediculatus*†
Authors: HECKMANN KLAUS 
Published: May 2007

ZUSAMMENFASSUNG. Der Süßwasserciliat Euplotes aediculatus beherbergt in seinem Cytoplasma 900–1000 stäbchenförmige Symbionten, die für seine Vermehrung essentiell zu sein scheinen. Durch Wachstum in Gegenwart von Penicillin kann Euplotes von seinen Symbionten befreit werden, es führt dies jedoch stets auch zu einem Verlust der Teilungsfähigkeit. Eine Reinfektion ist bei etwa 4% der Zellen möglich, die dann nach 4–5 Tagen sich wieder zu vermehren beginnen.Die Endosymbionten wurden sowohl lichtmikroskopisch als auch elektronenmikroskopisch untersucht. In ihrer Feinstruktur und Färbbarkeit gleichen sie, wie kappa und andere von Paramecium her bekannte “killer”‐Partikel, gramnegativen Bakterien. Sie unterscheiden sich von diesen Symbionten jedoch dadurch, daß ihre DNA im Cytoplasma nicht homogen verteilt ist, sondern sich in 3–9 schon lichtmikroskopisch erkennbaren Zentren konzentriert. Die in Euplotes vorkommenden Symbionten lassen keine “killer”‐Aktivität erkennen. Sie werden omikron‐Partikel genannt.SYNOPSIS. The fresh water ciliate Euplotes aediculatus contains in its cytoplasm 900–1000 rod‐shaped symbiotes which appear to be essential for division. Growth of Euplotes in the presence of penicillin results in loss of these symbiotes and simultaneously in a loss of the ciliate's ability to divide. Reinfection with the symbiotes can be achieved in 4% of the cells which then resume growth after a lag period of 4–5 days.The endosymbiotes have been studied by light and electron microscopy. In their fine structure and staining reaction they resemble gram‐negative bacteria as do kappa and other killer particles of Paramecium. The symbiotes of Euplotes, however, are unusual in that their DNA is not distributed throughout the cytoplasm but is localized in 3–9 areas (nucleoids), which are visible even in the light microscope. No killing activity seems to be associated with the symbiotes. Following the practice of referring to those endosymbiotes by Greek letters they are here designated omikron particles.
Isolation of Amylopectin Granules and Identification of Amylopectin Phosphorylase in the Oocysts of Eimeria tenella
Authors: WANG C. C. , WEPPELMAN R. M. , LOPEZ‐RAMOS B. 
Published: May 2007

SYNOPSIS. Amylopectin granules were purified from Eimeria tenella oocysts following digestion with sodium dodecyl sulfate and pronase. The oval granules had a uniform size of 0.5 × 0.7 μm, and consisted of only glucose polymers. α‐Amylase treatment yielded 235 nmoles of maltose from the granules from 106 unsporulated oocysts and 93 nmoles maltose from those from 106 sporulated oocysts.Amylopectin phosphorylase activity was detected in the cytoplasm of unsporulated oocysts of E. tenella. It had a specific activity of 13 U/mg protein in crude extracts, and a pH optimum of 6.0. The Km values determined were 9.1 mM for glucose‐1‐phosphate and 5.6 mM for glucose end groups in potato amylopectin. Enzyme activity declined at a linear rate during sporulation, sporulated oocysts containing less than 8% of the activity of unsporulated oocysts. No amylase‐type activity was found in the parasite.
Précisions Temporelles sur les Processus de la Stomatogenèse de Tetrahymena paravorax analysés en Microscopie Photonique
Authors: METENIER GUY , GROLIERE CLAUDE‐ALAIN 
Published: May 2007

Resume.Une analyse des séquences morphogénétiques du CiliéTetrahymena paravorax montre que: (A) La durée de la stomatogenèse de bipartition des formes microstomes en croissance exponentielle représente 45% du temps de génération (stade 1—20%; stade 2—3%; stade 3—3%; stade 4—5%; stade 5—5%; stade 6—9%). (B) La division cytoplasmique est inégale (les proters sont plus petits que les opisthes); la différence de taille initiale entre les 2 produits de fission est probablement compensée par une prolongation de la période de croissance chez le proter. (C) Le pourcentage maximum de réorganisation buccale microstome → macrostome pour les populations asynchrones atteint –˜ 70% au bout de 210 mn d'incubation dans la stomatine. (D) L'initiation de la stomatogenèse de remplacement oral est connectée avec la fin d'une période dont la durée minimale est approximativement celle du stade 0 du cycle normal d'interdivision des microstomes; cette initiation est retardée chez les microstomes exposés à la stomatine dès le début du cycle cellulaire. (E) Le primordium buccal de division peut se résorber en présence de stomatine et la stomatogenèse antérieure peut commencer avant que ne soit terminée cette résorption; la résorption n'est plus induite au‐delà d'un point du stade 5 qui précède le début de la constriction du corps cellulaire.SYNOPSIS.An analysis of the morphogenetic sequences in the ciliate Tetrahymena paravorax has shown that: (A) The duration of predivision stomatogenesis in exponentially growing microstomes occupies 45% of the generation time (stage 1—20%; stage 2—3%; stage 3—3%; stage 4—5%; stage 5—5%; stage 6—9%). (B) Cytoplasmic division is unequal (the proters are smaller than opisthes); the initial size difference between the 2 fission products is presumably compensated by an increased growth period in the proter. (C) The maximum percentage of microstome‐to‐macrostome oral reorganization is –˜ 70% in asynchronous populations, 210 min after suspension in stomatin. (D) Initiation of oral replacement stomatogenesis is associated with the end of a period which has a minimum duration nearly equal to that of stage 0 characteristic of the normal inter‐division cycle of the microstomes; this initiation is delayed if exposure of microstomes to stomatin is begun at the onset of the cell cycle. (E) The buccal primordium formed in division can be resorbed in presence of stomatin and anterior stomatogenesis can start before the resorption is completed: this resorption is not induced if the cells have progressed beyond a point which precedes the beginning of the cell furrowing (stage 5).
Tip Transformation in Tetrahymena: A Morphogenetic Response to Interactions Between Mating Types*
Authors: WOLFE JASON , GRIMES GARY W. 
Published: May 2007

SYNOPSIS.In Tetrahymena thermophila subline B, a morphogenic alteration of the anterior end of cells of mating types III and VII results from a cellular interaction which precedes and is a prerequisite for pairing. Cell pairing begins 1 h after starved cells of complementary mating type are mixed. The 1 h‐long lag period is characterized by an actinomycin D‐sensitive inductive interaction in the first 30 min, followed by a maturation period. Tip transformation begins during the maturation period and continues after pairing. Scanning electron microscopy of deciliated cells reveals ridges which form a chevron meeting in a midline seam between the oral apparatus and the anterior tip. During transformation, the seam broadens until the ridged surface is completely smooth. Melding of the ridges also occurs at the tip of the cell resulting in its blunted appearance. Cells of complementary mating types join in the region of this modified surface, which eventually becomes a specialized cell junction perforated by cytoplasmic bridges. Thus, pursuant to an inductive interaction the structure of the tip of cells is modified in anticipation of the pairing event. Rate of cell pairing might be limited by rate of tip transformation.
Attempted Cross‐Transmission of Coccidia Between Sheep and Goats and Description of Eimeria ovinoidalis sp. n.
Authors: McDOUGALD L. R. 
Published: May 2007

SYNOPSIS.Attempted infection of 2 young lambs with oocysts of Eimeria christenseni from a goat was unsuccessful. Negative results were obtained also when young kids were fed oocysts of Eimeria ninakohlyakimovae from sheep. There was no difficulty in infecting lambs with the sheep coccidium resembling E. ninakohlyakimovae nor goats with the goat coccidium E. christenseni. Oocysts from the goat measured 38.4 × 26.7 m̈m, but were easily distinguished from Eimeria ahsata from the sheep by sporocyst size and shape, and from Eimeria ovina by oocyst size. Eimeria ninakohlyakimovae‐like oocysts from sheep averaged 23.0 ×18.2 m̈m and were morphologically indistinguishable from previously reported goat coccidia.Since no cross infections of sheep and goats could be accomplished with oocysts of Eimeria sp. characteristic of one or the other host, I concluded that sheep coccidia previously known as E. ninakohlyakimovae are distinct from morphologically similar goat coccidia and therefore constitute a separate species. Since the name E. ninakohlyakimovae was first used for coccidia from the goat, the sheep coccidium is renamed Eimeria ovinoidalis with oocyst structure and endogenous stages similar to those previously described from the sheep.
The Fatty Acid Composition of Paramecium aurelia Cells and Cilia: Changes with Culture Age
Authors: KANESHIRO EDNA S. , BEISCHEL LINDA S. , MERKEL STEVEN J. , RHOADS DENNIS E. 
Published: May 2007

SYNOPSIS.The fatty acids of whole cells and cilia from Paramecium tetraurelia strains 51s and d,95 and from Paramecium octaurelia strain 299s were identified. Ciliates were grown axenically in 3 types of culture media. More than 30 fatty acid species were identified and their structures determined by gas chromatography, mass spectrometry, argentation chromatography, hydro‐genation, and fragmentation technics. The major fatty acids were hexadecanoic, octadecanoic, 9‐octadecenoic, 9,12‐octadecadi‐enoic, 6,9,12‐octadecatrienoic, and 5,8,11,14‐eicosatetraenoic acids. Minor variations in fatty acid compositions were observed in cells grown in the different culture media as well as among the 3 strains. Major changes in fatty acid compositions occurred with culture age and cell density. The cells accumulated exogenous lipids in cytoplasmic vesicles. These lipids were utilized as culture age progressed. Both cellular volume and lipid content were greater in young than in older cultures. Fatty acid compositions of both whole cells and cilia changed with age and had a relative decrease in saturated, short‐chained and odd‐numbered carbon acids. Cilia lipids were enriched in long‐chained, polyunsaturated acids as compared to lipids in whole cell extracts. Eicosatetra‐enoic acid (arachidonic acid) increased to the greatest extent with age in both cellular and ciliary lipids, accounting for 20–60% of the total fatty acids in cilia. The age‐related change in fatty acid composition in Paramecium is among the largest observed in eukaryotic organisms. It was concluded that some minor fatty acids found in Paramecium lipids were incorporated directly from certain culture media and that Paramecium had w3, 6, and 9 pathways for polyunsaturated fatty acid biosynthesis.
Emetine Binding to Ribosomes of Entamoeba histolytica—Inhibition of Protein Synthesis and Amebicidal Action*
Authors: ENTNER NATHAN 
Published: May 2007

SYNOPSISAfter demonstration that emetine is amebicidal by inhibiting protein synthesis, the question arose whether active protein synthesis is required for emetine's amebicidal effect. The answer appears to be “no,” as derived from experiments on intact amebae. Responses were compared for log‐ and stationary‐growth phase amebae. In the latter, protein synthesis is significantly slower, and sensitivity to emetine, i.e. degree of inhibition of protein synthesis, was maintained independently of rate of protein synthesis. Both stages equally bound tritiated emetine to their ribcsomes. Binding of [3H]emetine was not affected by certain drugs that interfere with energy metabolism, protein synthesis, and/or ribosomal function, e.g. dinitrophenol, puromycin, chloroquine, and acriflavin. High concentrations of EDTA combined with puromycin (which disaggregates ribosomes into their subunits) lowered binding by 50%.In chase experiments the ribosomes of intact amebae were prelabeled with [3H]emetine or [3H]isoemetine, then exposed to relatively high concentrations of unlabeled emetine. Labeled isoemetine was displaced almost completely, whereas no displacement of [3H]emetine occurred; evidently, the high stability of the emetine‐ribosome binding is due in part to a hydrogen‐bonding reaction of the C‐1' atom of the emetine molecule with the chain‐elongation site. Finally, evidence was obtained that capacity to bind emetine is an index of drug resistance.
Eimeria and Sarcocystis in Raccoons in Illinois1
Authors: ADAMS JOHN H. , LEVINE NORMAN D. , TODD KENNETH S. 
Published: May 2007

ABSTRACTEimeria nuttalli oocysts were found in 58% (21/36) and E. procyonis oocysts in 25% (9/36) of raccoons Procyon lotor in Illinois, and sporocysts of Sarcocystis sp. in 17% (2/12) of other raccoons in Illinois. The oocysts of E. nuttalli were ellipsoidal to ovoid. 15–21 × 12–17 μm, with a one‐layered, smooth, colorless wall. The oocysts of E. procyonis were 22–28 × 18–22 μm, with a rough, striated, brownish, two‐layered wall. The sporulated sporocysts of Sarcocystis sp. were 11–13 × 8–10 μm. Attempts to infect baby pigs by feeding them sporocysts of Sarcocystis sp. from the raccoon failed.
In Vivo and In Vitro Localization of Leishmania within Macrophage Phagolysosomes: Use of Colloidal Gold as a Lysosomal Label1
Authors: BERMAN JONATHAN D. , FIORETTI THOMAS B. , DWYER DENNIS M. 
Published: May 2007

ABSTRACTThe interaction of Leishmania with lysosomes within macrophages in vivo has been investigated. Lysosomes labeled with colloidal gold in vivo fused with phagocytic vacuoles containing Leishmania amastigotes within the macrophages of infected footpad tissue of BALB/c mice. This localization of Leishmania within macrophage phagolysosomes in vivo is the first confirmation for any obligate intracellulaire protozoon that parasite‐lysosome interactions in vitro occur in vivo.
Adaptive Use of N2‐Dimethyl‐Substituted Pterins by Cultures of Crithidia fasciculata1
Authors: ZIEGLER IRMGARD , BÖHME MANFRED , PFLEIDERER WOLFGANG , ELSTNER ERICH F. 
Published: May 2007

ABSTRACTThe compound 6‐(L‐erythro‐1,2′,3′‐trihydroxypropyl)pterin, at a concentration of 50 pg/ml (“L‐erythro‐neopteria”), supports half‐maximal growth of Crithidia fasciculata; biopterin at a concentration of 30 pg/ml is shown to yield similar growth. N2‐dimethyl‐6‐(L‐erythro‐1′,2′,3′‐trihydroxypropyl)pterin (A) was inactive even at 100 ng/ml. Synergism was observed with the N2‐dimethylamino derivative (A) in the presence of suboptimal biopterin, its activity then being of the order of L‐erythro‐neopterin. In contrast, the stereoisomeric N2‐dimethyl‐6‐(D‐erythro‐1′,2′,3′‐trihydroxypropyl)pterin (“dimethyl‐D‐erythro‐neopterin”) and its 3′‐mono‐phosphate only slightly enhanced growth under similar conditions but both threo‐isomers had no supplementary activity. Biopterin‐induced growth was slowed by 6‐(D‐erythro1′,2′,3′‐trihydroxypropyl)pterin (D‐neopterin); the threo‐isomers had no such effect. An adaptive demethylation capacity by growing cultures and competition of biopterin uptake by D‐neopterin seems likely. The report of the occurrence in Euglena of N2‐dimethyl‐6‐(L‐threo‐1′,2′,3′‐trihydroxypropyl)pterin and its 3′‐mono‐phosphate adds further interest to our observations.