bluuebunny/crossref_metadata_2025_split huggingface dataset:
Further Studies of Dopamine Metabolism and Function in Tetrahymena1
Authors: Gundersen Robert E. , Thompson Guy A. 
Published: May 2007

ABSTRACTThe large amounts of dopamine accumulated by cells of Tetrahymena pyriformis strain NT‐1 and secreted into their growth medium were found to depend primarily upon an extracellular, non‐enzymatic conversion of tyrosine to L‐dihydroxyphenylalanine (L‐DOPA); L‐DOPA was then rapidly taken into the ceils and transformed into dopamine enzymatically. Efforts to find physiologically significant dopamine binding sites on the cell surface or dopamine‐sensitive adenylate cyclase activity were unsuccessful, suggesting that the catecholamine does not function in Tetrahymena as it does in higher animals.
Biochemical Study of Proteins of Cortical Cytoskeleton in the Ciliate Isotricha prostoma1
Authors: Vigues Bernard , Metenier G. , Grolière C. A. , Grain J. , Sénaud J. 
Published: May 2007

ABSTRACTIn Isotricha prostoma, proteins of isolated cortices retaining the ecto‐endoplasmic fibrillar boundary (EEB) have been separated by one‐ and two‐dimensional gel electrophoresis. In addition to that of tubulin, four main bands corresponding to polypeptide molecular weights of 185, 35, 23, and 22 kd have been observed on 9% SDS‐polyacrylamide gels. Supernumerary major bands within a low molecular weight range (11‐19 kd) are evident after separation on 7.5‐15% polyacrylamide gradient gels. Two‐dimensional analysis discloses ‐ 150 polypeptide spots, most of them focusing within an acidic pl range 4.6‐5.3. The cortical fibrillar structures are still distinguishable after incubation in solutions containing 1.0 M K. Cl (12 h) or 0.6 M Kl (8 h). A prolonged KI treatment (52 h), however, results in the removal of EEB filaments (˜4 nm in diameter) and of a large part of the kinetid elements, so that the insoluble material is mainly represented by a reticulum of 6‐nm filaments interconnecting the proximal regions of kinetosomes. Two proteins with MW of 58 and 63 kd appear to be constituents of this kinetosome‐associated filamentous reticulum. Some of the cortical proteins with MW ≤23 kd are the most likely candidates for components of EEB filaments. The absence of decoration with heavy meromyosin confirms that actin is not a major component of Isotricha cortical cytoskeleton.
Nutritional Requirements of Plasmodium falciparum in Culture. II. Effects of Antimetabolites in a Semi Defined Medium1
Authors: Geary Timothy G. , Divo Alan A. , Jensen James B. 
Published: May 2007

ABSTRACTA semi‐defined minimal medium, in which pantothenic acid is the only vitamin, was used to culture Plasmodium falciparum for the analysis of antimetabolite drugs. Analogs of riboflavin, nicotinamide, pyridoxine, and thiamin inhibited the growth of this parasite; for each drug, effects were much more pronounced after 96 h of exposure compared to 48 h. The most potent drug examined was 8‐methylamino‐8‐desmethyl riboflavin (IC50 value approximately 1.0 times 10‐10 M at 96 h). Avidin, a protein which complexes and thus inactivates biotin, did not affect parasite viability. Other antimalarial drugs, including chloroquine and quinine derivatives and antibiotics, were equipotent in the minimal medium and in RPMI 1640. Four strains of P. falciparum showed only minor differences in sensitivity to these antimetabolites. The use of prolonged drug exposure times and a vitamin‐depleted medium allowed the preliminary characterization of antimalarial antimetabolites in vitro.
Effects of Intestinal Contents from Normal and Immunized Mice on Sporozoites of Eimeria falciformis1
Authors: Douglass Thomas G. , Speer Clarence A. 
Published: May 2007

ABSTRACTThe interaction of Eimeria falciformis sporozoites with the intestinal epithelium and with the intestinal contents from the cecum and colon of normal and specifically immunized mice was studied by light (LM) and scanning electron (SEM) microscopy. Fecal (FM) and enterocyte‐associated (EAM) mucus were removed from the cecum and colon of normal mice and mice that had been immunized 1, 6, 12, or 20 days earlier with a series of oral inoculations of E. falciformis oocysts. Sporozoite‐specific IgA, but neither IgM nor IgG, was detected by the immunofluorescent antibody test in FM and EAM from immunized mice. No sporozoite‐specific immunoglobulin was detected in normal mice. When examined by LM, sporozoites exposed to all FM and EAM preparations exhibited greater motility and excystation from sporocysts. At 4 h after incubation in FM or EAM from normal or immune mice, about 10% of the sporozoites appeared damaged, being non‐motile and non‐refractile. Immune FM and EAM caused agglutination of sporozoites and sporocysts and oocyst walls of E. falciformis. but did not agglutinate those of E. ferrisi. Scanning electron microscopy of in vitro interactions between E. falciformis sporozoites and intestinal contents revealed that sporozoites exposed to immune EAM were coated with particulate material whereas those exposed to normal EAM were relatively clean. Sporozoites exposed to immune FM were usually embedded within the mucus whereas those exposed to normal FM were situated on top of the mucus. No significant differences occurred between the length/width (L/W) ratios of sporozoites incubated in normal FM and EAM or in PBS. Sporozoites exposed to immune FM had significantly greater L/W ratios than those exposed to normal FM whereas those exposed to immune EAM had significantly shorter L/W ratios than ones exposed to normal EAM. Few of the sporozoites observed on the luminal surface of the colon and cecum of normal mice were covered by mucus and none was altered in shape or showed pellicular damage. Only a few sporozoites were observed on the luminal surface of the colon and cecum of immunized mice. Most of these were covered by mucus and some exhibited pellicular alterations.
Myxosporean Infections in Cultured Tilapias in Israel1
Authors: Landsberg Jan H. 
Published: May 2007

ABSTRACTFive new species of myxosporean parasite are described from cultured tilapias in Israel. These are: Myxosoma sarigi. Myxosoma equatorialis, Myxobolus israelensis. Myxobolus agolus, and Myxobolus galilaeus. The first four were found in hybrids of Oreochromis aureus x Oreochromis niloticus while Myxobolus galilaeus was found in Sarolherodon galilaeus. In addition, M. sarigi. M. israelensis, and Myxobolus sp. were also found in S. galilaeus. In the light of the present study, the taxonomy of myxosporean infections in tilapias is modified. Mature spores may localize in the melano‐macrophage centers of the spleen and kidney where ihey may eventually be destroyed. Nc cases of mortality have so far been associated with these parasites.
The 5S and 5.8S Ribosomal RNA Sequences of Tetrahymena thermophila and T. pyriformis1
Authors: VAN BELL CRAIG T. 
Published: May 2007

ABSTRACTThe nucleotide sequences of the 5S rRNAs of Tetrahymena thermophila and two strains of T. pyriformis have been determined to be identical. The 5.8S rRNA sequences have also been determined; these sequences correct several errors in an earlier report. The 5.8S rRNAs of the two species differ at a single position. The sequencing results indicate that the species are of recent common ancestry. Molecular evidence that has been interpreted in the past as suggestive of an ancient divergence has been reviewed and found to be consistent with a T. pyriformis complex radiation beginning approximately 30–40 million years ago.
Trypanosoma brucei: Differentiation of in Vitro‐Grown Bloodstream Trypomastigotes into Procyclic Forms1
Authors: SIMPSON AGDA M. , HUGHES DALLAS , SIMPSON LARRY 
Published: May 2007

ABSTRACTTrypanosoma brucei strain 366D trypomastigotes grown at 37°C in the presence of a human fibroblast cell line formed foci underneath the feeder cells whereas trypanosomes grown in the presence of a human epithelial cell line grew only in the culture supernatant. A culture system was developed to study the differentiation of bloodstream trypomastigotes grown in the epithelial cell system into procyclic trypomastigotes at 27°C. The morphological differentiation into the procyclic form was complete by 48 h. Cell division did not occur until 30–40 h after transfer to 27°C. Various characteristics of this system were examined, including the effect of the feeder layer, the type of medium, the presence of the metabolites cis‐aconitate and citrate, the preadaptation period, and the trypanosome cell concentration. The respiration of the recently differentiated procyclic cells was less sensitive to inhibition by CN‐than that of established procyclic forms, implying a delayed appearance of complete mitochondrial oxidative pathways. This trypanosome differentiation system has the advantage that the animal host is not needed and the entire process is carried out in in vitro culture.
Ultrastructural Features of Mitosis in Anisonema sp. (Euglenida)1
Authors: TRIEMER RICHARD E. 
Published: May 2007

ABSTRACTThe fine structure of stages in mitosis in a colorless euglenoid, Anisonema sp., reveals that chromosomes remain condensed throughout the life cycle and are attached to the nuclear envelope at interphase. The onset of mitosis is marked by the anterior migration of the nucleus towards the base of the reservoir and by elongation of the nucleolus. The nuclear envelope persists throughout mitosis. Microtubules are generated in the peripheral nucleoplasm adjacent to the envelope and attach to the chromosomes while they are still associated with the envelope. The region of microtubular contact develops into a distinct layered kinetochore as the developing spindle with attached chromosomes separates from the nuclear envelope and moves into the nucleoplasm. The mature spindle consists of a number of subspindles each containing about 8–10 microtubules and a few associated chromosomes. Both chromosomal and non‐chromosomal microtubules are present in each subspindle and extend towards the envelope terminating at or near the nuclear pores. Chromosomal segregation is concomitant with nuclear elongation. By late division, an interzonal spindle develops in the dumbbell‐shaped nucleus and nucleolar separation occurs. Continued invagination of the nuclear envelope in the region of the interzonal spindle eventually separates the daughter nuclei. A remnant of the interzonal spindle persists in the cytoplasm until cytokinesis.
The Cytology of Sheep Rumen Ciliates. III. Ultrastructure of the Genus Entodinium (Stein)1
Authors: FURNESS D. N. , BUTLER R. D. 
Published: May 2007

ABSTRACTThis study examines previously undescribed general and cytopharyngeal features of the genus Entodinium. The cytopharynx contains three types of microtubular ribbons underlying the cytostomal membrane as well as a loose palisade of nematodesmata. A protoesophagus composed of microtubular bundles associated with a fibrous wall lies internally to one side of an extrusible peristome on which the adoral zone of syncilia (AZS) is mounted. Macronuclear structures are very similar to those of other ophryoscolecids. The micronucleus has chromatin bodies forming a compact mass but lacks the thick wall found in other species. A tubular spongiome surrounds the contractile vacuole and the cytoproct is relatively undifferentiated. Cortical structure follows the usual five‐layered ophryoscolecid pattern with subcortical barren kinetosomes arranged into indistinct kineties. The infraciliature of the AZS has kinetosomes set upon a subkinetal rod and with associated bifurcated kinetodesmata and transverse microtubules, some of which extend into the cytopharynx. Components newly described for Entodinium are the one to three postciliary microtubules and the interkinetosomal centro‐lateral strand, all of which are present in other species of ophryoscolecid ciliates. The infraciliature of the paralabial ciliary tuft shows similar components to that of the main AZS, but lacks the subkinetal rod. The microtubular components of the cytopharynx are discussed in relation to the “alimentary” structures in other ophryoscolecids, and a relationship of these structures to dietary differences is suggested.
Oral Monokinetids in the Free‐Living Haptorid Ciliate Enchelydium polynucleatum (Ciliophora, Enchelyidae): Ultrastructural Evidence and Phylogenetic Implications1
Authors: FOISSNER WILHELM , FOISSNER ILSE 
Published: May 2007

ABSTRACTSpecial ultrastructural characteristics of the haptorid soil ciliate Enchelydium polynucleatum Foissner, 1984 are the restriction of the parasomal sacs to the area of the “brush” and finger‐like projections of the food vacuole membrane into the lumen of the vacuole. The general organization of the infraciliature is similar to that of Spathidium and some buetschliids because the anterior ends of the somatic kineties are condensed and obliquely bent. Enchelydium is similar to haptorids and buetschliids in possessing monokinetid somatic fibrillar structures with the classical fibrillar associates: 1) a short kinetodesmal fiber; 2) two transverse microtubular ribbons; 3) a long postciliary microtubular ribbon; and 4) a system of overlapping subkinetal microtubules, which seems to be absent in the buetschliids. Unlike Spathidium and all other haptorids so far investigated ultrastructurally, serial sections show that there are no oral dikinetids, as in the endocommensal buetschliids and balantidiids. Instead, three to six anterior kinetids in each ciliary row have nematodesmal bundles extending into the cytoplasm and surrounding the cytopharynx. These kinetids lack cilia and all fibrillar associates except enlarged transverse ribbons, which extend anteriorly and inwards to support the cytopharynx. Other similarities between the buetschliids and Enchelydium are the conspicuous rough endoplasmic reticulum and abundant sausage‐like vesicles in the oral region. As in other haptorids, Enchelydium has two types of toxicysts and one type of mucocyst. These observations strongly suggest that Enchelydium belongs to the ancestral stock of both the Haptorida and the Archistomatida. The similarities in the somatic and oral infraciliature and ultrastructure of the Haptorida and the Archistomatida suggest that they belong to the same subclass, Haptoria Corliss, 1974.
Symbiont‐Induced Strain‐Specific Lethal Effect in Amoebae
Authors: LORCH I. J. , KIM H. B. , JEON K. W. 
Published: May 2007

ABSTRACTThe cytosol fraction of a symbiont‐bearing strain of Amoeba proteus exerted a lethal effect when injected into symbiont‐free amoebae of the original strain. The lethal factor appeared to be a protein with a molecular weight of over 200,000. While the effect of the lethal factor on the nucleus was reversible, the host cytoplasm was permanently damaged so that it could not form a viable cell when combined with a normal nucleus.
Detection of the Microtubule Cytoskeleton of the Coccidian Toxoplasma gondii and the Hemoflagellate Leishmania donovani by Monoclonal Antibodies Specific for β‐Tubulin1
Authors: SCHWARTZMAN JOSEPH D. , KRUG EDWARD C. , BINDER LESTER I. , PAYNE MICHAEL R. 
Published: May 2007

ABSTRACTSeven monoclonal antibodies specific for mammalian β‐tubulin demonstrate the microtubule cytoskeleton of Toxoplasma gondii and Leishmania donovani by indirect immunofluorescence microscopy. Immunoblots of T. gondii and L. donovani proteins separated by SDS polyacrylamide gel electrophoresis confirm the specificity of the monoclonal antibodies for tubulin. Differential staining of flagellar and subpellicular microtubule populations was not seen in L. donovani with these antibodies. All seven antibodies also detected the subpellicular microtubules of T. gondii, but the polar ring and conoid of this organism was not visualized by any of them. This technique provides a rapid and specific way to assess microtubular organization in whole organisms.
Protozoa as Hosts for Endosymbioses and the Conversion of Symbionts into Organelles1,2
Authors: CAVALIER‐SMITH T. , LEE JOHN J. 
Published: May 2007

ABSTRACT.Protozoa may be thought of as preadapted to serve as hosts for cellular endosymbionts by virtue of their widespread ability to take up particles by endocytosis. The absence of the cell wall so characteristic of plants and fungi and the commonly large size of most protozoa are additional factors favoring protozoan cells for endosymbioses. The conversion of symbiont into a cellular organelle (e.g. a mitochondrion or chloroplast) is more complicated, especially since the latter do not code for all of their own proteins. Thus, such conversions are held to be rare. Among protozoa, numerous foraminifera appear to have characteristics making them very favorable as hosts for certain algae. Such adaptations, both physiological and morphological in nature, are discussed. Also discussed in this paper are the ways by which (present‐day) chloroplasts and mitochondria may have been derived from early endosymbionts: a single ancestral cyanobacterium, in the first case, and a single ancestral purple‐nonsulfur bacterium, in the second. Mechanisms for insertion of proteins into and across the organellar membranes had to be evolved for all genes transferred from the symbionts into the host nucleus.
Possible Adaptive Value of Endosymbionts to Their Protozoan Hosts1,2
Authors: LEE JOHN J. , LEE MONICA J. , WEIS DALE S. 
Published: May 2007

ABSTRACT.It is generally accepted that in symbiotic systems involving algal species as cellular endobionts there is some positive benefit to the host organisms. In this paper special consideration is given to the larger foraminifera, protozoa that serve as very useful model systems for the study of aspects of inter/intracellular integration and adaptation—living, as they do, in nutrient‐limited but well illuminated shallow tropical seas and containing endosymbiotic algae in abundance. A considerable amount of information is now available on physiological as well as morphological adaptations of the host species to pigmented protists representing diverse algal divisions (phyla). Brief mention is also made of bacterial endosymbionts of certain ciliates.
Chemosensory Responses in Tetrahymena: The Involvement of Peptides and other Signal Substances1
Authors: LEICK VAGN , HELLUNG‐LARSEN PER 
Published: May 2007

Starved Tetrahymena thermophila (or cells growing in Holz's defined medium) are attracted by a chemosensory response to complex peptide mixtures as proteose peptone, yeast extract, and extracts of blood platelets containing platelet‐derived growth factor. Starved cells are also significantly attracted by mixtures of amino acids and of nucleosides of Holz's defined medium; however, no individual amino acid or nucleoside could be identified as the major chemo‐attractant.The positive chemosensory response can be abolished by cycloheximide (CHX) but is insensitive to actinomycin D and puromycin, possibly indicating that de novo RNA and protein synthesis are not necessary for a change in chemosensory behavior. Three mutants resistant to CHX show normal response in the presence of the drug.The possible role of peptides as naturally occurring food signals of Tetrahymena is discussed.
Ultrastructural Study and Description of Ovavesicula popilliae N. G., N. Sp. (Microsporida: Pleistophoridae) from the Japanese Beetle, Popillia japonica (Coleoptera: Scarabaeidae)1
Authors: ANDREADIS THEODORE G. , HANULA JAMES L. 
Published: May 2007

ABSTRACTA new genus and species of microsporidia, Ovavesicula popilliae n. g., n. sp., is described from the Japanese beetle, Popillia japonica, on the basis of studies by light and electron microscopy. Parasite development primarily occurs within the Malpighian tubules of larvae, and spores are formed in a sporophorous vesicle. Meronts have diplokaryotic nuclei, develop in direct contact with the host cell cytoplasm, and divide by binary fission. Sporonts have unpaired nuclei, develop within a thick sporophorous vesicle, and undergo synchronous nuclear divisions producing plasmodia with 2, 4, 8, 16, and 32 nuclei. Cytokinesis of sporogonial plasmodia does not occur until karyokinesis is complete with 32 nuclei. Intact sporophorous vesicles are ovoid, containing numerous secretory products, and are surrounded by a persistent two‐layered wall. The uninucleate spores are regularly formed in groups of 32, and the polar tube in each has six coils.
In Vitro Excystation of Cryptosporidium baileyi from Chickens1
Authors: SUNDERMANN CHRISTINE A. , LINDSAY DAVID S. , BLAGBURN BYRON L. 
Published: May 2007

ABSTRACTRelease of sporozoites from the oocysts of Cryptosporidium baileyi is described from Nomarski interference‐contrast microscopy. Just prior to excystation, the four sporozoites became motile and rearranged themselves within the oocyst. The sporozoites were then rapidly expelled through an opening that formed in the oocyst wall, and the residuum was either released or retained within the oocyst. Excysted sporozoites were crescent shaped and measured 5.0–9.0 μm × 1.0–1.6 μm (x̄= 6.8 × 1.1 μm). Excystation occurred when sodium taurocholate or a mixture of trypsin and sodium taurocholate was present in the incubation medium. High levels of excystation occurred at 37° or 40°C, but excystation did not occur at 4°C. The ability of biles from two avian and two mammalian hosts to produce excystation of C. baileyi was also studied. After a 2‐h incubation at 40°C, the percentages of excystation were 69.5% in goat bile, 45.0% in pig bile, 33.0% in chicken bile, and 34.5% in turkey bile.
Trypanosoma vivax: Adaptation of Two East African Stocks to Laboratory Rodents1
Authors: GATHUO H. K. W. , NANTULYA V. M. , GARDINER P. R. 
Published: May 2007

ABSTRACTTwo Trypanosoma vivax stocks from East Africa have been adapted to rats and mice. Adaptation was induced by rapid passage at two‐ to four‐day intervals in sublethally irradiated rats. After 200 such passages, the two stocks gave rise to parasitemias of 109–1010 trypanosomes/ml in peripheral blood, and the infection was fatal in 90% of the rats. By passaging the rat‐adapted T. vivax into normal mice at two‐ to three‐day intervals for over 200 passages, the two stocks also became pathogenic to mice. One of the stocks was also capable of maintenance in non‐irradiated rats. The two stocks displayed a marked degree of pleomorphism in irradiated and non‐irradiated rats and mice. In the early rising parasitemia, the organisms were predominantly short, with a well formed undulating membrane, a pointed posterior end, and a large terminal kinetoplast. As parasitemia approached its peak, the organisms transformed into long, slender forms with an inconspicuous undulating membrane, an elongated posterior end, and a sub‐terminal kinetoplast. The short forms associated with the early, rising parasitemia were more infective for mice than the long forms encountered at peak parasitemia. Although the two rodent‐adapted stocks retained their pathogenicity for goats, neither the original stocks nor their corresponding rodent‐adapted stocks could be cyclically transmitted by tsetse flies. The availability of these stocks will greatly facilitate investigations on East African T. vivax which would otherwise be difficult to carry out in experimental rodents.
A Redescription of the Life Cycle of Eimeria mitis Tyzzer, 1929
Authors: NOVILLA M. N. , JEFFERS T. K. , GRIFFING W. J. , WHITE S. L. 
Published: May 2007

ABSTRACTTen‐day‐old broiler chickens were inoculated with oocysts of a characterized strain of Eimeria mitis, and tissues were fixed at 4, 8, or 24‐h intervals after inoculation for histopathological examination. Tissue collections were initiated at the time of inoculation and extended up to 168 h postinoculation. The preferred site of development of E. mitis was found to be the ileum although more limited development of the parasite also took in the jejunum, cecal pouches, cloaca, and bursa of Fabricius. No distinctive and consistent intestinal lesions were macroscopically evident even in heavily parasitized chickens. The prepatent period was approximately 92 h postinoculation. The histopathological features of the E. mitis infections were characterized using conventional bright‐field microscopy as well as both scanning and transmission electron microscopy. No extra‐intestinal development of the parasite was observed.