bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Fate of RNA Degradation Products in Starved Cultures of Tetrahymena pyriformis W.*
Authors: KOROLY MARY J. , CONNER ROBERT L. 
Published: May 2007

SYNOPSISThe RNA content of a population of Tetrahymena pyriformis W was followed during the growth phases of the culture. The cellular RNA levels were found to reach a maximum in early log phase and to decrease throughout the remainder of the log and deceleration phases. There was a 25% decrease in RNA amount when cells in late stationary phase were compared to those in deceleration. This loss of RNA was mimicked when cells from the deceleration phase were suspended in a non‐nutrient buffered medium.Procedures were established to determine RNA content and the intra‐ and extracellular distribution of RNA degradation products, namely purine and pyrimidine bases and orthophosphate. Balance sheets are presented to show that the decrease in RNA levels was accompanied by an equivalent increase in purine and pyrimidine bases and phosphorus derivatives. The validity of the procedures employed was demonstrated. The influence of magnesium, cholesterol and glucose on the cells suspended in a non‐nutrient buffer was examined. Each was found to affect the ultimate distribution of RNA products in a characteristic fashion suggesting that each compound acts by a different mode of action.
Life Cycle of Isospora canis Nemeséri, 1959 in the Dog*
Authors: LEPP DONALD L. , TODD KENNETH S. 
Published: May 2007

SYNOPSISThe life cycle of I. canis Nemeséri, 1959 was studied in experimentally infected dogs. Freshly sporulated oocysts were ovoid and 34–40 × 28–32 μm. The endogenous stages were found directly beneath the epithelium of the distal portion of the small intestinal villi. Most of the endogenous stages were in the lower 1/3 of the small intestine, but occasionally they were found in other portions of the small intestine. Three asexual generations were present. First‐generation schizonts were 16–38 × 11–23 μm and contained 4–24 merozoites; mature 1st‐generation merozoites were 8–11 × 3–5 μm. First‐generation schizogony lasted up to 7 days after inoculation. Second‐generation schizonts were 12–18 × 8–13 μm and contained up to 12 merozoites which were 11–13 × 3–5 μm. Second‐generation schizogony was present on postinoculation days 6 and 7. Third‐generation schizonts were formed by nuclear division of 2nd‐generation merozoites. Most 2nd‐generation merozoites underwent nuclear division without leaving the parasitophorous vacuole of the 2nd‐generation schizont. Mature 3rd‐generation schizonts were 13–38 × 8–24 μm and contained 6–72 merozoites. Third‐generation merozoites were 8–13 × 1–3 μm. Third‐generation schizogony was present on days 6–8 after inoculation. Mature macrogametes were 22–29 × 14–23 μm. Mature microgametocytes were 20–38 × 14–26 μm. Gametes were present on postinoculation days 7–10. Oocysts were present in tissue sections on postinoculation days 8–10 and 12. The prepatent period was 9–11 days.
Ultrastructural Changes During Encystment of Schizopyrenus russelli*
Authors: MAITRA S. C. , SAGAR P. , AGARWALA S. C. 
Published: May 2007

SYNOPSISUltrastructural changes associated with the encystment of Schizopyrenus russelli have been studied by electron microscopy. Before encystment small “black bodies” appear in the cytoplasm and later migrate toward the periphery. The outer cyst wall is secreted at this stage as a thin discontinuous layer which thickens and subsequently becomes continuous. Concomitant with this, the endoplasmic reticulum surrounds the mitochondria. The inner cyst wall later appears as a multilayered structure which presumably is cast off from the plasma membrane. Between the inner and outer layers of the cyst wall, there is a middle, less electron‐dense layer wherein extruded cytoplasmic material is found embedded at certain places.
Cytologic and Autoradiographic Studies of the Micronucleus at Meiotic Prophase in Tetrahymena pyriformis
Authors: SUGAI TOSHIRO , HIWATASHI KOICHI 
Published: May 2007

SYNOPSISMicronuclear changes of variety 1 of Tetrahymena pyriformis during meiotic prophase have been observed by the light microscope. Morphologic changes in the micronucleus are divided into 6 stages. In stage I, chromatin begins to polarize; in stage II, the micronucleus becomes spindle shaped; and in stage III, one end of the micronucleus protrudes to form a “neck.” In stage IV, where the micronucleus elongates to maximal length, the whole micronucleus consists of 2 chromatin threads pairing longitudinally. One thread probably contains one genome. In stage V, the elongated thread becomes shorter and thicker. Finally, in stage VI, separate chromosomes appear and enter into metaphase.To discover the role of the elongation of the micronucleus, called crescent formation, autoradiographic analysis of RNA and DNA synthesis were undertaken using [3H]uridine and [3H]thymidine. Pulse label and chase experiments show that the crescent in stages II and III is actively synthesizing RNA. Though no remarkable DNA synthesis was observed during meiosis, a small amount of DNA synthesis occurred during the 1st and 2nd prezygotic divisions.
Agglutination of Trypanosoma cruzi by Concanavalin A*
Authors: ALVES M. J. M. , COLLI W. 
Published: May 2007

SYNOPSISEpimastigotes of Trypanosoma cruzi obtained in culture agglutinate readily with low concentrations of concanavalin A (Con A). Agglutination was linear with time up to 10 min providing that the initial cell density was greater than 1 × 108 cells/ml. Under these conditions, the percentage agglutination was dependent on the Con A concentration. Agglutination was inhibited by α‐methyl D‐mannoside, α‐D‐mannose, and α‐D‐glucose. Pretreatment of cells with trypsin had no effect on the epimastigote agglutinations.Blood forms (trypomastigotes) of T. cruzi did not agglutinate even in the presence of 100 times more Con A. Results suggest differences in membrane structure between blood forms and cultured epimastigotes of T. cruzi. These membrane differences might be related to the different pathogenic properties of both cell forms of T. cruzi.
Mating Reaction and its Daily Rhythm in Euplotes crassus*†
Authors: MIYAKE AKIO , NOBILI RENZO 
Published: May 2007

SYNOPSISThe agglutinative mating reaction of Euplotes crassus occurred without lag if complementary mating types were brought together under appropriate conditions. Only a small fraction of the cell population reacted at the beginning but the number of reacting cells steadily increased until firmly united pairs were formed after ∼30 min. The intensity of the initial mating reaction changed rhythmically; the rhythm appeared circadian. Mating‐type‐specific soluble factors did not appear to participate in this reaction. The results strongly support the positive‐feedback hypothesis of the mating reaction presented by Heckmann & Siegel in 1964. Patterns of preconjugant cell interactions of different ciliates are discussed.
Influence de la Concentration Bacterienne sur la Croissance de Colpidium campylum*
Authors: DIVE DANIEL 
Published: May 2007

RÉSUMÉ. L'étude de la phase de latence et du début de la phase exponentielle de croissance dans des cultures monoxéniques de Colpidium campylum a été réalisée en examinant l'influence de la concentration en bactéries à la fois sur le nombre d'individus, leur volume moyen et le biovolume total de la population de Ciliés. Il est possible de définir plusieurs phénomènes liés à l'abondance du substrat, en particulier une concentration critique conditionnant la maintenance de la population et une diminution du taux d'assimilation consécutive à une suralimentation.A partir des résultants obtenus, la notion de volume minimum nécessaire à la division et l'interaction entre l'énergie nécessaire à la synthèse de matière vivante et celle liée à la nutrition, sont discutées afin d'expliquer l'évolution des cultures.SYNOPSIS. In a study of the stationary and the early exponential growth phases of the monoxenic cultures of Colpidium campylum, the influence of the bacterial concentration upon the number of ciliates, their mean volume, and the biomass of the total ciliate population was examined. It is possible to identify several phenomena linked to the abundance of the substrate, particularly a critical concentration affecting the maintenance of the ciliate population, and a decrease of the assimilation rate following overfeeding.On the basis of the results obtained, an estimate of the minimum volume necessary for division as well as the interaction between the energy required for the synthesis of living matter and that derived from nutrition are discussed, to explain the development of the cultures.
Studies on the Conditions Required for Optimum Recovery of Tetrahymena pyriformis Strain S (Phenoset A) after Freezing to and Thawing from –196 C
Authors: OSBORNE JACQUELINE A. , LEE DONALD 
Published: May 2007

SYNOPSISThe toxicity of several cryoprotective agents was tested at room temperature (23 C) against Tetrahymena pyriformis strain S (Phenoset A) at different stages of the growth cycle. Polyvinylpyrrolidone (PVP‐40) at 10% (v/v) concentration was without effect at any stage in the growth cycle, while 1.2 M glycerol immobilized the cells which were disrupted very shortly afterwards. The toxicity of 0.25 M glucose was largely independent of the position of the cells in the growth cycle, but the toxicity of 0.25 M sucrose and 1.4 M dimethylsulfoxide (DMSO) was most marked in late log‐ and stationary‐phase cells. After log‐phase cells had been equilibrated with 1.4 M DMSO for 1 hr, the number of cells surviving cooling at defined rates from 0.45 to 12 C/min decreased as the final temperature decreased from –30 to –60 C.A temperature of –53 C was found to be the optimum from which cells cooled at a given rate could be cooled rapidly to –196 C. Nevertheless, when cells were cooled at defined rates to –35, –45, or –53 C and then rapidly to –196 C the optimum rate of cooling to these temperatures was found to be 1 C/min. The optimum rate of cooling to –60 C prior to plunging into liquid nitrogen was found to be 2.7 C/min.
A Branched‐chain Amino Acid Aminotransferase from the Rumen Ciliate Genus Entodinium
Authors: WAKITA MASAAKI , HOSHINO SADAO 
Published: May 2007

SYNOPSISA branched‐chain amino acid aminotransferase was extracted from rumen ciliates of the genus Entodinium and was partially purified by Sephadex G‐200, DEAE‐cellulose and DEAE‐Sephadex A‐50 column chromatography. The purified enzyme was active only with leucine, isoleucine and valine, and required pyridoxal phosphate as cofactor. The amino acids competed with each other as substrates. The enzyme had optimal activity at pH 6.0 in phosphate buffer. The Km values for the substrates and cofactor are as follows: 1.66 for leucine; 0.90 for isoleucine; 0.79 for valine; 0.29 mM for α‐ketoglutarate: and 0.1 μM for pyridoxal phosphate. Enzyme activity was inhibited by p‐chloromercuribenzoate and HgCl2. Gel filtration indicated the enzyme to have a molecular weight of 34,000.
Mucocysts in the Heterotrich Ciliate Spirostomum*
Authors: WINET H. , JONES A. R. 
Published: May 2007

SYNOPSISMucus‐like secretions by Spirostomum are demonstrated by a combination of anatomic and hydrodynamic technics whereby the presence of mucocysts and trails formed by their secretions can be shown. The mucocysts in this heterotrich differ somewhat in form and content from those reported for hymenostomes. It is suggested that the mucuslike secretions aid in lubrication when the ciliate swims near a solid boundary and reduce unsteady hydrodynamic effects when the organism swims in unobstructed fluid.
Differences in the Life Cycles Between a Vaccine Strain and an Unmodified Strain of Babesia bovis (Babes, 1889) in the Tick Boophilus microplus (Canestrini)*
Authors: STEWART N. P. 
Published: May 2007

SYNOPSIS. Developmental forms of 2 strains of Babesia bovis (Babes) were studied in the tick vector Boophilus microplus (Canestrini). One strain (designated T) was shown to be infective for the tick, and the other (NT) to have lost infectivity for the tick, because of repeated blood passaging in cattle.Parasites of the 2 strains in gut contents of adult female ticks were similar during the first 16 h post‐repletion (PR), but thereafter their structure differed. From 16–64 h PR, the majority of T strain parasites were spherical and without processes. During the next 32 h elongate forms and vermicules developed. Fission bodies were seen within epithelial cells of the gut by 96 h PR. T‐strain parasites in gut contents decreased in number from ∼ 96 h and were difficult to find at 144 h, the time of the final observation.In contrast, NT strain parasites were plentiful throughout the period of observation. They were predominantly spherical, ranging in diameter from 1.5 to 15 μm. Forms with obvious processes measuring up to 81 μm in length were seen in large numbers at seemingly regular intervals from 16–144 h PR, suggesting that a process of development and divisions was being repeated. No vermicules or fission bodies were seen.T‐strain, but not NT strain parasites, were seen in hemolymph and ova of the ticks and in their larval progeny. It is suggested that continuous blood passaging of the NT strain had resulted in selection of parasites incapable of penetrating gut epithelial cells of the tick.
Plasmodium falciparum in Culture: Improved Continuous Flow Method*
Authors: TRAGER WILLIAM 
Published: May 2007

SYNOPSIS.A new design of flow vessel provides a method for continuous culture of P. falciparum in a settled layer of human erythrocytes with a slow flow of culture medium over them. The parasitemia is kept fluctuating from ˜ 1%, just after addition of fresh erythrocytes. to ˜ 10%, 2 or 3 days later. Each vessel provides each week 3 harvests, each containing ˜ 0.6–1 × 109 parasites.
Acid and Neutral Hydrolases in Trypanosoma cruzi. Characterization and Assay*
Authors: AVILA JOSE LUIS , CASANOVA MARIA ARGELIA , AVILA ANGELA , BRETANA ANTONIO 
Published: May 2007

SYNOPSISTwelve acid hydrolases, 4 near‐neutral hydrolases and alkaline phosphatase were demonstrated in 0.34 M sucrose homogenates of Trypanosoma cruzi strain Y: p‐nitrophenylphosphatase and α‐naphthylphosphatase, with optimum pH at ˜ 6.0; α‐galactosidase, β‐galactosidase, β‐glucosidase, N‐acetyl‐β‐glucosaminidase, cathepsin A and peptidase I and III, with optimum pH between 5.0 and 6.0: and arylsulfatase cathepsin D, α‐arabinase and α‐mannosidase with optimum pH at ˜ 4.0 α‐Glucosidase, gluccse‐6‐phosphatase and peptidase II had optimum pH at ˜ 7.0. β‐Glycerophcsphatase had a broad pH‐activity curve from 4.0 to 7.4, with maximum activity at pH 7.0. The main kinetic characteristics of these enzymes and their quantitative assay methods were studied.No activity was detected for α‐fucosidase, β‐xylosidase, β‐glucuronidase, elaidate esterase. acid lipase, and alkaline phospho‐diesterase.
Phénomènes Périodiques, Métaboliques et Structuraux Chez un Protiste, Euglena gracilis
Authors: LEDOIGT G. , CALVAYRAC R. 
Published: May 2007

RESUME.Des divisions synchrones chez Euglena gracilis Z peuvent ětre obtenues par différentes méthodes. Lorsque les cellules sont cultivées sur milieu contenant du lactate comme seule source de carbone, des divisions synchrones sont observables, indépen‐damment des conditions d'éclairement. Toutefois, il existe une relation entre la phase des divisions cellulaires et les périodes lumière‐obscurité appliquée à la culture.Pendant le cycle cellulaire, nous montrons que les synthèses des macromolécules sont discontinues: c'est le cas pour les ADN nucléaire et mitochondrial, les ARN ribosomaux et non‐ribosomaux, ainsi que pour certaines protéines (cytochrome c 558). Des variations cycliques touchant la morphologie des mitochondries et des chloroplastes sont observées. Au cours du cycle cellulaire, les processus métaboliques séquentiels accompagnent les modifications de structure des organites. C'est ainsi qu'en début du cycle, au commencement de la phase G1, sont synthétisés les ribosomes cytoplasmiques et qu'ensuite, chez les euglènes vertes, les ARN non‐ribosomaux sont formés.Ces synthèses d'ARN précèdent l'accroissement du chondriome et du plastidome dans la cellule. En milieu de phase G1, une nouvelle synthèse d'ARN non‐ribosomal commence et est observée avant la synthèse des ADN nucléaire et mitochondrial. En fin de phase G1, démarre la division des organites à partir du chondriome et du plastidome en réseau.SYNOPSIS.Synchronous divisions of Euglena gracilis strain Z can be obtained by various methods. When the cells are cultivated in a medium containing lactate as the sole carbon source, synchronous divisions are observed, independent of the conditions of illumination. Nevertheless, there exists a relationship between the phase of cell division and the periods of light and darkness applied to the culture.During the cell cycle, the synthesis of macromolecules is discontinuous—this is true of nuclear and mitochondrial DNA, ribosomal and nonribosomal RNA, and certain proteins (cytochrome c 558). Cyclic variations in the structure of mitochondria and chloroplasts are also observed. In the course of the cell cycle, sequential metabolic processes accompany structural modifications of the organelles. Also, at the beginning of the cycle, at the start of phase G1, the cytoplasmic ribosomes are synthesized, and then, in green euglenids, nonribosomal RNAs are formed. These syntheses of RNA precede enlargement of the chondriome and plastids. In mid‐G1 phase, a new synthesis of RNA begins, which precedes synthesis of nuclear and mitochondrial DNA. At the end of G1 phase, division of organelles starts, beginning with the chondriome and plastids, arranged in a network.
Intranuclear Parasitism of the Ciliate Euplotes by a Trypanosomatid Flagellate
Authors: WILLE JOHN J. , WEIDNER EARL , STEFFENS W. L. 
Published: May 2007

ABSTRACTA trypanosomatid flagellate, Leptomonas sp., develops and multiplies in the macronucleus (only) of natural and laboratory‐reared populations of the ciliate Euplotes. Up to 90% of the natural populations of Euplotes in our test pond had such nuclear infections. Laboratory infections were transmitted to this ciliate by feeding it liberated parasites. Paramecium resisted infections. All laboratory‐induced infections were lethal to Euplotes, while control clones of the uninfected ciliates remained viable. This leptomonad, unlike Leptomonas karyophilus (found in Paramecium), shows no leishmanial forms in its several ciliate hosts and shows a varied pattern of locomotion.
Spore Germination in the True Slime Mold Didymium nigripes1
Authors: KERR NORMAN S. 
Published: May 2007

ABSTRACTThe morphology of spore germination in Didymium nigripes was studied using scanning electron microscopy and Nomarski phase optics. First, the outer spore wall splits, revealing a fibrillar inner wall. Remnants of the inner wall continue to cover the newly emerged amoeba. A single nucleus and a prominent vacuole are visible throughout germination. Germination is more rapid in glucose‐peptone‐yeast extract than in phosphate buffer. Germination is completely inhibited at 4°C, and is very slow at 18°C. Germination is most rapid at 26°C; at 21°C or 32°C it is slightly slower. Germination is reversibly inhibited by 20 μ/ml cycloheximide, but not by 200 μ/ml 5‐fluoro uracil or 200 μ/ml proflavin. It is completely inhibited by 10‐3 M Na azide.
The Germination of Vavraia culicis Spores1
Authors: UNDEEN ALBERT H. 
Published: May 2007

ABSTRACTBuffered solutions of KCl and NaCl were tested for their stimulatory effect on the germination of variously‐aged spores of Vavraia culicis. Germination was optimal in 0.2 M KCl, pH 6.5 for one isolate, and, for another isolate, peaks of germination occurred at pH 7.0 and 9.5. Spores incubated for several hours in suboptimal solutions became unable to germinate under optimal conditions. After being returned to water, they regained their ability to germinate. Calcium chloride, magnesium chloride, and ammonium chloride inhibited germination. After ingestion by mosquito larvae, spores germinated near the posterior end of the midgut.
Stage‐Dependent Toxicity of N‐Acetyl‐Glucosamine to Plasmodium falciparum1
Authors: Gupta Suresh K. , Schulman Seymour , Vanderberg Jerome P. 
Published: May 2007

ABSTRACTThe effects of N‐acetyl‐glucosamine on growth of synchronized cultures of Plasmodium falciparum were assessed by morphological observations and by measurement of parasite incorporation of 3H‐hypoxanthine. Inhibition of 3H‐hypoxanthine incorporation was more marked during the later stages of the erythrocytic cycle. At concentrations of the sugar below 20 mM, however, the deleterious effects were mainly a result of failure of released merozoites to invade erythrocytes, rather than a failure of schizonts to mature or release merozoites. These results are compatible with the hypothesis that a lectin‐like substance on the merozoite interacts with a surface glycoprotein on the red cell and that sugar residues on this glycoprotein may be involved in this recognition.
Mating‐Type Polymorphic Variation in Euplotes minuta (Ciliophora: Hypotrichida)1
Authors: Dini Fernando , Luporini Pierangelo 
Published: May 2007

ABSTRACTAn investigation was carried out to probe into the mating‐type structure of a local population of the marine ciliate, Euplotes minuta. From this population, nine different mating types belonging to a unique set were isolated. The nine type‐representative wild stocks analyzed were found to be heterozygous at the mating‐type (mat) locus and provided, together with their sexual progeny, a total of 15 pure mating types. In E. minuta, the high‐multiple nature of the basic mating system controlled by a series of peck‐order alleles at a single locus should be considered a virtual certainty. The relationships among the genetic economies of the similar bottom‐dwelling marine ciliates of the genus Euplotes, the E. vannus‐crassus‐minuta group, are discussed.
Formation of the Cyst Wall of the Ciliate Colpoda steinii
Authors: RUTHMANN AUGUST , KUCK ANGELIKA 
Published: May 2007

ABSTRACTAfter a thin membranous envelope surrounding the cell body and cilia of Colpoda steinii has been formed, the main mass of the proteinaceous cyst wall is deposited without exocytosis. It can be composed of two layers, the denser and wrinkled ectocyst and the smooth‐walled endocyst; however, the ectocyst may be missing. Evidence is presented that ecto‐ and endocyst are formed from vesicles derived from abundant rough endoplasmic reticulum which appears at the time of wall formation. The cilia are retained and become embedded in the peripheral cytoplasm. Synthesis of RNA and protein is required as actinomycin C and cycloheximide block cyst formation. Calcium is required during a sensitive phase prior to encystment.