bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Age and Sex on the Acquisition of Immunity to Toxoplasmosis in Cats*
Authors: DUBEY J. P. , HOOVER E. A. , WALLS K. W. 
Published: May 2007

SYNOPSIS. The effects of age and sex of the cat on oocyst shedding, multiplication of Toxoplasma gondii in tissues of cats, and acquisition of immunity were investigated after oral inoculation of cats with Toxoplasma cysts. Twenty‐five cats varying in age from 1 week to 39 months were killed 7‐97 days after inoculation with T. gondii. Homogenates of brain, heart, mesenteric lymph nodes, retina, and blood from these cats were inoculated into mice to test for Toxoplasma infectivity. Toxoplasma was isolated more frequently and in higher titers in mice receiving inocula from cats of the youngest age group (1 week old). Toxoplasma gondii was isolated from tissues of only 2 of 21 cats older than 2 months (at the time of inoculation), although all of the animals shed oocysts within 1 week after ingesting the parasites.The number of oocysts shed varied among littermates of the same sex and between sexes. Generally, cats younger than 12 months shed more oocysts than older cats. The number of oocysts shed by older cats varied considerably; males generally shed more oocysts than the females. However, the numbers of cats examined were too small for statistical comparison. Nevertheless, the observations suggest that cats older than 12 months should not be used in experiments where numbers of oocysts shed is critical.
Sporozoites of Rodent and Simian Malaria, Purified by Anion Exchangers, Retain their Immunogenicity and Infectivity
Authors: MOSER GINA , BROHN FREDRICK H. , DANFORTH HARRY D. , NUSSENZWEIG RUTH S. 
Published: May 2007

SYNOPSIS. Sporozoites of rodent malaria, Plasmodium berghei, and simian malaria, Plasmodium knowlesi and Plasmodium cynomolgi, were partially separated from mosquito debris and microbial contaminants by passage of Anopheles material through a DEAE‐cellulcse column. In addition to eliminating most of the contaminants (80–90%), this simple technic has made it possible to recover rapidly large numbers of viable sporozoites (55–75% yield), which have retained their infectivity, immunogenicity, and capacity to react with known antisera. Mice injected with varying doses of column‐purified sporozoites (CS) of P. berghei produced infections which paralleled those seen in the controls. Total protection against challenge with a potentially lethal dose of viable sporozoites was acquired by mice inoculated twice with irradiated CS of P. berghei. CS of P. berghei and P. cynomolgi gave positive circumsporozoite precipitation (CSP) reactions, upon inoculation with the respective immune sera. The preservation of the surface antigens of CS was documented by immunofluorescence.It was shown that differences in elution behavior exist among sporozoites of certain species of Plasmodium as well as among sporozoites of the same species derived from different organs of the mosquito. These results may be attributed to differences in the surface charge of the sporozoites or conditions in sample media.Purified sporozoites obtained by the method described in this report provide an adequate source of parasites for a variety of in vitro studies.
Ultrastructural Observations on Renal Schizogony of Leucocytozoon dubreuili in the American Robin
Authors: WONG STEVE T. C. , DESSER SHERWIN S. 
Published: May 2007

SYNOPSIS. The schizogonic development of Leucocytozoon dubreuili in the kidney proximal tubule cells of the American robin, Turdus migratorius, was studied by electron microscopy. Renal schizogony is initiated by the entry of certain hepatic merozoites into cells of the proximal tubules. Development of the schizont consists of a coordinated sequence of events including extensive mitotic nuclear division, multiplication of mitochondria, increase in endoplasmic reticulum and ribosomes, differentiation of membranes, microtubules, micronemes and rhoptries, and cytoplasmic segmentation (cytomere formation). Merozoites form by budding around numerous centers in the schizont and, when mature, are bounded by a single plasma membrane subtended by microtubules. Each merozoite contains a large nucleus, a mitochondrion, and a well developed apical complex consisting of 3 polar rings, paired rhoptries, and numerous micronemes.An atypical nuclear division observed in some maturing schizonts was characterized by the multiple fission of a nucleus within a persistent outer nuclear membrane and the absence of mitotic spindle apparatus. Alterations in infected renal cells consisted of disorganization and loss of cytoplasmic organelles and the accumulation of lipofuscin‐like inclusions.
Light and Electron Microscopic Observations of Gametogenesis in Hastigerina pelagica (Foraminifera)*
Authors: SPINDLER M. , ANDERSON O. R. , HEMLEBEN C. , BÉ A. W. H. 
Published: May 2007

SYNOPSIS. During gametogenesis mother individuals of Hastigerina pelagica (d'Orbigny) undergo significant morphological changes. Thirty h before gamete release, the cytoplasm changes from pale orange to bright red, possibly due to transport of stored lipids from the inner region to more peripheral parts of the cytoplasm. During the next 10 to 15 h the bubble capsule which surounds the calcareous shell is discarded. After all bubbles have disappeared, the individual sheds its spines by resorbing the spine bases close to the shell surface.A single mother nucleus divides into some hundreds of thousands of gamete nuclei within a span of ∼ 20 h. A bulge of cytoplasm is extruded from the aperture and increases in size during the next 5 to 10 h. This bulge consists of cytoplasmic strands in which gametes and spherical bodies are embedded. The gametes and spherical bodies mature and are released during the afternoon and early evening. The gametes have 2 unequal acronematic flagella. A previously undescribed structure in foraminiferal reproduction is the spherical body which consists of a large vacuole surrounded by a thin cytoplasmic layer in which several nuclei, various typical cell organelles and multiple flagella are present. The spherical bodies are believed to play a role as receptacles of waste material, possibly including residual digestive enzymes, thereby protecting the gametes from lysis during the reproductive process. Fusion of gametes and further development into the next generation have not been observed.
Clonal Growth of Entamoeba histolytica and other Species of Entamoeba in Agar*
Authors: GILLIN FRANCES D. , DIAMOND LOUIS S. 
Published: May 2007

SYNOPSIS. This is the first description of a method for growing axenized Entamoeba histolytica as colonies from single cells in agar suspension. Factors affecting the efficiency of colony formation included unknown characteristics of the amebal strain, age of cells used, and the type and concentration of agar employed. Colony formation was dependent upon filling deep vessels (culture tubes or tissue culture flasks) with agar, probably to maintain reduced oxygen tension, and upon solidifying the agar rapidly at 0 C. It was demonstrated in a study with the drug metronidazole that the agar colony method was useful for quantifying cell viability in drug testing.Eleven of 12 E. histolytica strains tested, as well as one Entamoeba terrapinae, one Entamoeba barreti, and 3 Entamoeba invadens strains formed colonies in agar suspension. E. histolytica‐like amebae (Laredo type) and E. moshkovskii formed only tiny colonies in agar.
Population Dynamics of Herpetomonas ampelophilae, with a Note on the Systematics of Herpetomonas from Drosophila spp.
Authors: ROWTON EDGAR D. , McGHEE R. BARCLAY 
Published: May 2007

SYNOPSIS Previous surveys of feral Drosophila melanogaster in Clarke County, Georgia, indicated 10 to 30% of the flies were parasitized with Herpetomonas ampelophilae. In the present study, herpetomoniasis in D. melanogaster reared in population cages rose from 0.01% to 90% in 14 days. The infection fluctuated between 5% and 100% during the 250 days in which the ageledeme was maintained.Herpetomonas were found endotrophically, peritrophically, and in the Malpighian tubules. In population cages, although there were sporadic rises in percentages, peritrophic and Malpighian tube infections usually remained low. Endotrophic infections often reached 100%, with individual flies being heavily parasitized. Although Chatton felt that several species of Herpetomonas inhabit a single species of Drosophila, we suggest that all the Herpetomonas in D. melanogaster be referred to as H. ampelophilae.
Regulation of Macronuclear DNA Content in Tetrahymena thermophila*†
Authors: DOERDER F. P. 
Published: May 2007

Synopsis.Unequal macronuclear division in Tetrahymena thermophila introduces variance into G1 macronuclei; unless eliminated such variance would result in continuous variation in DNA content. Analysis of G1 and G2 macronuclear variances reveals that the added variance is eliminated by action on the extremes of macronuclear DNA content. In this model (Model II), macronuclei with small amounts of DNA have an additional complete S phase, while those with large amounts of DNA skip S. From available data, chromatin extrusion is shown not to contribute significantly, if at all, to the elimination of variance. Computer simulations utilizing haploid subunits indicate that model II predictions apply reasonably well to experimental data in terms of coefficients of variation, mean DNA content, and frequency of additional and skipped S phases. The simulations reveal also that within certain constraints, particularly the thresholds for additional and skipped S phases, macronuclear assortment is unaffected by Model II regulation. The relationships between Model II and other aspects of the cell cycle are briefly discussed.
Microscopic Observations on the Filopodia of Entamoeba histolytica*
Authors: LUSHBAUGH WILLIAM B. , PITTMAN FRED E. 
Published: May 2007

SYNOPSISLiving Entamoeba histolytica trophozoites were examined by phase‐contrast microscopy. Intact critical point dried trophozoites were examined by transmission electron microscopy at an accelerating voltage of 1000 kV (HVEM) and by scanning electron microscopy (SEM). Half and quarter m̈ thick sections of epoxy‐embedded trophozoites were examined by HVEM. Many of the trophozoites of 2 strains examined had surface filopodia, 1 to over 100 pan in length. The cytoplasm of filopodia was continuous with the cytoplasm and bounded by surface plasmalemma bearing a glycocalyx. Structures called “surface‐active lysosomes with trigger,”“dendritic plasmalemmal extensions,” and “extra‐amebic vesicles” by previous investigators probably represent portions of filopodia demonstrated in the present study. Filopodia appear to be of frequent normal occurrence in E. histolytica and may function in: (a) endocytosis or pinocytosis; (b) exocytosis; (c) attachment to substratum; (d) penetration of tissue; (e) release of cytotoxic substances; or (f) contact cytolysis of host cells.
Acetate Oxidation by Bloodstream Forms of Trypanosoma cruzi*
Authors: DOCAMPO ROBERTO , CRUZ FERNANDO S. , LEON WILSON , SCHMUNIS GABRIEL A. 
Published: May 2007

SYNOPSISBloodstream forms of Trypanosoma cruzi had a substantial increase in respiration in the presence of acetate. Oxidation of acetate took place via the tricarboxylic acid cycle and involved an antimycin A‐sensitive respiratory pathway. Oxygen uptake in the presence of acetate was as sensitive to antimycin A inhibition as was CO2 production. There was a 6–7% residual O2 uptake which was not inhibited by high antimycin concentrations. Human anti‐T. cruzi sera had no effect on oxygen uptake.
Preparation and Properties of Mitochondria from Naegleria gruberi*
Authors: WEIK R. R. , JOHN D. T. 
Published: May 2007

SYNOPSISWhole cell respiration rates were measured polarographically for Naegleria gruberi during growth in agitated cultures. Log growth phase amebae consumed 80 ng atoms O/min/mg cell protein. At stationary phase, respiration rate decreased 4–fold. Intact mitochondria were isolated from N. gruberi and their oxidative and phosphorylative capacities were studied polarographically. As with the mammalian system, the mitochondria oxidized succinate and NAD‐linked substrates, but unlike rat liver mitochondria, those from the protozoan rapidly oxidized citrate and NADH. The rates of substrate oxidation were ADP‐dependent, with ADP:O ratios equalling ˜ 2.8 for NAD‐linked substrates and ˜ 2.2 for succinate. The respiratory control ratios. 2 to 4 for 11 substrates, were dependent on Pi, Mg2+, and serum albumin. Potassium cyanide, azide, malonale, and rotenone inhibited electron transport the same way as that of the mammalian system: however, amytal inhibited both glutamate and succinate respiration. Pentachlorophenol, DNP, and bilirubin uncoupled oxidation from phosphorylation. Difference spectra of oxidized and dithionite‐reduced mitochondria had distinct absorption bands of flavins and of c‐, b‐, and α‐type cytochromes.
Changes in the Classification of Several Major Taxa of Ciliophora on the Basis of a Numerical Phenetic Analysis*,†
Authors: LYNN DENIS H. 
Published: May 2007

SYNOPSIS. Several taxonomic problems arising from recent revisions of the phylum Ciliophora. Initially, electro‐ and light‐microscopic features of 7 species from 4 genera of colpodid ciliates were analyzed by several numerical phenetic procedures. The phenogram derived by using Jaccard's coefficient as the measure of similarity and the unweighted pair‐group arithmetic clustering method (UPGMA) yielded a classification with the highest cophenetic correlation coefficient.Subsequently, relationships among 22 oligohymenophoran and related genera were determined by analyzing 57 ultrastructural and light‐microscopic features with Jaccard's coefficient and UPGMA. On the basis of these results, the suborder Peniculina is elevated to ordinal rank and the family Turaniellidae is transferred from the Peniculida to the Tetrahymenina. The phenogram also indicated that the nassuline ciliates may be allied with the OLIGOHYMENOPHORA rather than the KINETOFRAGMINOPHORA.
Multiconjugant Complexes of Euplotes Crassus: an Instance of Coordination of Nuclear Events*,†
Authors: LUPORINI PIERANGELO , GIACHETTI CINZIA 
Published: May 2007

SYNOPSIS In the ciliate Euplotes crussus, doublet cells of 3 complementary mating types were mixed and multiconjugant complexesobtained. The cells were not uniform in the G, stage at the time of mixing. Despite asynchrony, the nuclear events of conjugationstarted and progressed coordinately in all the members of each complex, leading to a synchronous exchange of pronuclei. An adjustmentof the cellular timing takes place before the nuclei of multiconjugants begin dividing. This adjustment probably occurs through specificciliary contact during preconjugant interaction.
Studies on the Macronuclei of Doublet Paramecium tetraurelia: Distribution of Macronuclei and DNA at Fission*
Authors: BERGER JAMES D. , MORTON GLENN T. 
Published: May 2007

SYNOPSIS. Doublet Paramecium tetraurelia would be expected to contain 2 macronuclei if their nuclear complement were strictly analogous to that of singlets. However, most doublets are unimacronucleate. It is shown in this study that dimacronucleate cells are present only in young clones. Unimacronucleate cells arise either through abnormalities in the determination and distribution of macronuclear anlagen during the first cell cycle after conjugation, or from dimacronucleate cells through abnormal division and segregation of macronuclei during the fission process.When a change in the number of macronuclei occurs through abnormalities in the division and segregation of daughter macronuclei, the daughter cells produced typically have DNA contents more similar than those expected from either random segregation of daughter macronuclei, or from the normal segregation pattern in ciliates in which changes in the number of macronuclei in progeny cells do not occur. This suggests that part of the regulation process of macronuclear DNA content in Paramecium may occur through control of the segregation pattern of daughter macronuclei.
Protist Biogeography1
Authors: BAMFORTH STUART S. 
Published: May 2007

ABSTRACTAutecology (cellular organelles and secretions, encystment and dispersal abilities), environmental conditions (physiological tolerances and interaction with other organisms), and evolutionary history contribute to protist biogeography, which manifests ecological and historical aspects. Ecological biogeography is seen in the influence of geochemistry on the distribution of fresh‐water phytoflagellates and algae, and of moisture and vegetation type on soil‐litter protists. A temporal feature is often present because many protists encyst and respond only to certain ranges of temperature and organic content. Historical biogeography has occurred by radiative host evolution on symbiotic protozoa (e.g., termite flagellates and rumen ciliates), and by the isolating effects of water currents, temperature, and density gradients on oceanic protists (coccoliths, dinoflagellates, foraminifera, radiolaria, and tintinnines). These two aspects combine in protists living on animal surfaces. Humans affect protist biogeography by increasing parasite ranges through human migrations and by water pollution. They can diminish these situations by disease control and exploiting appropriate ciliates in sewage disposal. Many free‐living protozoa appear to be cosmopolitan, but mating types and isoenzyme studies suggest that speciation with its geographic connotations may be more widespread than presently appreciated.
Aufwuchs Protozoa and Bacteria on the Gills of the Rock Crab, Cancer irroratus Say: A Survey by Light and Electron Microscopy1
Authors: BODAMMER JOEL E. , SAWYER THOMAS K. 
Published: May 2007

ABSTRACTHistological examination of gills of the rock crab (Cancer irroratus Say, 1917) taken from specimens collected in polluted and nonpolluted areas indicated that gill discoloration was not directly related to the degree of microbial fouling. Light microscope studies demonstrated that bacteria, peritrich and suctorian ciliates, and some naviculoid diatoms were the principal members of the fouling community. Examination of the bacteria by electron microscopy showed that several distinct types were present, and that some of these were attached to the gill by holdfast structures while others were enmeshed in a filamentous slime layer. An unusual small marine flagellate and an unidentified amoeba were also examined ultrastructurally.
Mitosis of Micronuclei During Division and Regeneration in the Ciliate Stentor coeruleus1
Authors: RAIKHEL NATASHA , PAULIN JEROME J. , SKARLATO SERGE O. 
Published: May 2007

ABSTRACTStages of mitosis of the micronuclei of Stentor coeruleus were described as seen by transmission electron microscopy. Cells in division and those regenerating new oral membranelles were studied. Microtubules were found in early prophase in the karyoplasm and interspersed between the condensing chromatin. A monaxial intranuclear spindle is formed by early metaphase, with kinetochore microtubule attachment sites on the chromosomes. The spindle elongates, separating the daughter nuclei at anaphase. A new nuclear envelope, consisting of two unit membranes, begins to form at late anaphase. Small segments of membrane found in the space between the newly forming and the old micronuclear envelopes appear to fuse to form the new nuclear envelope. No ultrastructural differences were found in the mitotic nuclei of cells in division or regeneration.
Electrically Induced Tentacle Retraction in the Suctorian Protozoon Discophrya collini (Root)1
Authors: HACKNEY CAROLE M. , BUTLER R. D. 
Published: May 2007

ABSTRACTDiscophrya collini is a free‐living suctorian with retractile tentacles covered by a thick fibrous cortex. The tentacles contain a microtubular central canal surrounded at the base by a fibrous collar. Electrical stimulation induces a reproducible tentacle retraction. With extracellular electrodes, the tentacles nearest the anode respond initially, contracting by up to 75% of their original length. There is an inverse relationship between voltage level and duration of stimulus in producing a threshold response, and at a set voltage, between duration and degree of retraction. With intracellular electrodes, the membrane potential has been measured as ‐30 mV, and tentacle retraction occurs in response to as little as 1.25 nA when the intracellular electrode is made the cathode of the circuit. SEM studies show that retracted tentacles have a wrinkled cortex, while TEM shows that the microtubular canal bends as it enters the cytoplasm. No consistent changes occur in the microtubule configuration of the canal on retraction, suggesting that the microtubules are not directly involved in the contractile mechanism.
Identification of Surface Proteins on Viable Plasmodium knowlesi Merozoites
Authors: JOHNSON JAMES G. , EPSTEIN NAVA , SHIROISHI TSUGIYE , MILLER LOUIS H. 
Published: May 2007

ABSTRACTViable merozoites of Plasmodium knowlesi were isolated and the proteins that were labeled on intact merozoites by lactoperoxidase‐catalyzed radioiodination were identified. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiography of Triton soluble extracts of labeled merozoites demonstrated eight major bands ranging in apparent molecular weight from 150,000 D to 22,000 D. Exposure of intact merozoites to trypsin (10 μg/ml) for 10 min resulted in the loss of the two highest molecular weight proteins (150,000 D and 105,000 D) and the appearance of two new bands at 70,000 D and 62,000 D. Trypsin treatment under these conditions also removed the receptor(s) for merozoite attachment to erythrocytes. Therefore, these high molecular weight proteins are candidates for the merozoite component that attaches to erythrocytes. There was no evidence that the labeled membrane components were serum or erythrocyte membrane components, two potential contaminants in the preparation. Anti‐rhesus erythrocyte antibody did not precipitate labeled merozoite proteins. Furthermore, the immunoprecipitation of labeled merozoite proteins by rhesus anti‐merozoite serum was not inhibited by erythrocyte ghosts.
Kinetoplast DNA in Trypanosoma equinum1
Authors: CUTHBERTSON ROBIN SHERYL 
Published: May 2007

ABSTRACTIdentification and characterization of kDNA is described in the naturally occurring totally dyskinetoplastic species Trypanosoma equinum. Fluorescence microscopy of live cells, using the highly sensitive and specific probe DAPI (4,6,‐diamidino‐2‐phenyl‐indole), showed the presence of a diversity of extranuclear fluorescent bodies scattered along the length of the organism. Transmission electron microscopic studies revealed a close similarity between the distribution of these DAPI‐fluorescing particles and of dense aggregates of nonfibrillar material resembling the kDNA of dyskinetoplastic strains of other species. Variable sized remnants of kDNA, occurring singly or in clusters, were found scattered throughout the mitochondrion. Analytical cesium chloride ultracentrifugation of total cellular DNA extracts showed a kDNA banding profile at a buoyant density equal to 1.691 gm/cm3, representing approximately 11% of the total cellular DNA content. Molecular spreads of isolated kDNA revealed a population of open circular molecules ranging in contour length from 0.11–9.69 μm.