bluuebunny/crossref_metadata_2025 huggingface dataset:
Appendages Associated with Glugea stephani, a Microsporidan Found in Flounder1
Authors: TAKVORIAN PETER M. , CALI ANN
Published: May 2007

During an electron microscopic study of Glugea stephani, three morphologically distinct tubular appendages that are continuous with the sporoblast plasmalemma were observed. The tubules were designated as: type I, 45–50 nm in diameter and 600–900 nm in length; type II, 25–35 nm in diameter, averaging 1300 nm in length; type III, 50–70 nm in diameter and with an indeterminate length, which often exceeds 3000 nm. Type III tubules contain regularly spaced, electron‐dense particles that are approximately 30 nm in diameter. Since many genera of microsporida have some type of appendage, which may eventually be utilized for taxonomic purposes, we propose the formation of a system of serially numbered detailed descriptions of these structures to promote uniformity and clarity in future publications.
Leishmania: Chemotaxic Responses of Promastigotes and Macrophages In Vitro1
Authors: BRAY R. S.
Published: May 2007

Promastigotes of Leishmania move progressively up a concentration gradient of: various sugars, specific sugars attracting individual species of Leishmania; serum albumin and another unidentified constituent of serum; hemoglobin; and a factor generated by promastigotes in NNN medium. The movement of promastigotes up a concentration gradient of serum is optimal at a pH of 6.4 to 6.8 and a temperature of 28°C and above. Cholinergic and adrenergic agents did not affect the attraction of serum for promastigotes. and cyclic nucleotides, inflammatory mediators, and macrophage products were not chemotaxic. It is postulated that the sugar chem‐otaxins influence the movement of promastigotes from the sand fly midgut to the esophagus, and serum chemotaxins may play a part in the entry of promastigotes into the skin of a mammal from the proboscis.

Macrophages, the host cell of the obligate intracellular Leishmania species, were not attracted to any product of promastigotes. When, however, promastigotes interact with serum, complement is activated to form C5a which is chemotaxic for macrophages. Activation of complement by promastigotes is, at least partially, by the alternate pathway. Other chemotaxins resulting from promastigote interaction with serum may also be present. Promastigotes may also produce inhibitors of C5a activity.
Monoclonal Antibodies to Toxoplasma Cell Membrane Surface Antigens Protect Mice from Toxoplasmosis1,2
Authors: JOHNSON ALAN M. , MCDONALD P. J. , NEOH S. H.
Published: May 2007

Groups of mice were given an intraperitoneal injection of one of six monoclonal antibodies to Toxoplasma gondii, a mixture of equal amounts of five monoclonal antibodies to T. gondii, or the murine myeloma protein MOPC 21, and challenged with either a highly virulent or moderately virulent parasite strain. Two monoclonal antibodies (FMC 19 and FMC 22) conferred total protection against the moderately virulent challenge, with all mice surviving, whereas 90% of control mice died. FMC 19 and FMC 22 also conferred significant protection against the highly virulent challenge as indicated by a prolonged mean time to death (MTD) of immunized compared with control groups of mice. One monoclonal antibody (FMC 23) and the mixture of five antibodies gave significant protection against the moderately virulent challenge only. Passive immunization with dilutions of FMC 22 antibody indicated that the lowest serum titer needed to confer significant protection to mice against a moderately virulent Toxoplasma challenge was 1/640. Mice challenged with highly virulent tachyzoites that had been preincubated with FMC 22 had a significantly longer MTD than mice challenged with highly virulent tachyzoites that had been preincubated with MOPC 21 or phosphate buffered saline, pH 7.2 (PBS). Immunoprecipitation and autoradiography of radiolabeled tachyzoites confirmed that FMC 19 was directed against a 35,000 molecular weight (mol. wt.) antigen and FMC 22 was directed against a 14,000 mol. wt. fraction. The potential for use of single antigens as protective immunogens in preventing toxoplasmosis is raised.
Identification of Surface Antigens of Sarcocystis muris (Coccidia)
Authors: ABBAS MOHAMMED K. , POWELL EDWIN C.
Published: May 2007

Zoites of Sarcocystis muris were recovered from the skeletal muscles of infected mice by trypsin digestion. Extracts of zoites prepared by freeze‐thaw, Triton X‐100 (0.1%), or a combination of the two treatments contained antigenic components. Testing of these antigens by agar gel diffusion and immunoelectrophoresis against sera from infected mice showed one major precipitin band.

SDS‐polyacrylamide‐gel electrophoresis (SDS‐PAGE) of the extracts revealed at least eight detectable polypeptides ranging in molecular weight from 10,000 to 220,000. The antigenic components of the extract were identified by labeling the parasite surface with [125I] and precipitation of the [125I]‐labeled antigens with immune sera. Analysis of the immunoprecipitates by SDS‐PAGE and autoradiography revealed three antigens with molecular weights of 27,500, 43,000 and 90,000. The smallest of these was the predominant antigen as suggested by labeling intensity.
Chemically Defined Media for the Cultivation of Naegleria: Pathogenic and High Temperature Tolerant Species
Authors: NERAD THOMAS A. , VISVESVARA GOVINDA , DAGGETT PIERRE‐MARC
Published: May 2007

Chemically defined minimal media for the cultivation of high temperature tolerant and pathogenic Naegleria spp. have been developed. A defined minimal medium, identical for N. fowleri and N. lovaniensis, consists of eleven amino acids (arginine, glycine, histidine, isoleucine, leucine, methionine, phenylalanine, proline, threonine, tryptophan, and valine), six vitamins (biotin, folic acid, hemin, pyridoxal, riboflavin, and thiamine), guanosine, glucose, salts, and metals. Three of the four strains of Naegleria fowleri tested (ATCCr̀30100, ATCCr̀30863, and ATCCr̀30896) and two strains of N. lovaniensis (ATCCr̀30467 and ATCCr̀30569) could be cultured beyond ten subcultures on this medium. For N. fowleri ATCCr̀30894 diaminopimelic acid, or lysine, or glutamic acid was also required. Mean generation time was reduced and population density increased for all strains with the introduction of glutamic acid. Glucose could be eliminated from the minimal medium only if glutamic acid was present. Without glucose, mean generation time increased and population density decreased. Diaminopimelic acid could substitute for lysine for ATCCr̀30894, indicating that Naegleria species may synthesize their lysine via the DAP pathway. Naegleria fowleri ATCCr̀30100 could be adapted to grow without serine or glycine in the minimal medium with glutamic acid added, but with mean generation time increased and population density decreased. The strain could be grown in the minimal medium in the absence of metals. For growth of N. australiensis ATCCr̀30958, modification of the medium by increasing metals ten‐fold, substituting guanine for guanosine and adding lysine, glutamic acid, and six vitamins (p‐aminobenzoic acid, choline chloride, inositol, vitamin B12, nicotinamide, and Ca pantothenate) was required.
Patterned Arrays of Intramembranous Particles in the Bristle Cilia of Three Different Species of Euplotes1
Authors: DALLAI ROMANO , LUPORINI PIERANGELO
Published: May 2007

Freeze‐fractured cells of three marine species of Euplctes (E. crassus, E. raikovi, and E. rariseta) show bristle cilia with patterned arrays of intramembranous particles. Such arrays are essentially of three types, in different positions along the bristle shaft. One array is located near the bristle base and shows a plate‐like shape. It appears in a close spatial correspondence with the lasiosome network, which is a structure consisting of interconnected electron‐dense bodies lying in between the peripheral axonemal doublets and the bristle membrane. The second type of array, apparently typical of only E. raikovi, consists of eight to ten longitudinal rows of particles that occupy most of the intermediate portion of the bristle. The third type of array appears differently shaped in different species and occurs at the bristle apex.
An Ultrastructural Study of Mitosis in a Marine Dinoflagellate: Prorocentrum minimum1
Authors: FRITZ LAWRENCE , TRIEMER RICHARD E.
Published: May 2007

An ultrastructural study on mitosis in the marine dinoflagellate Prorocentrum minimum is described. Early in mitosis the nuclear membrane invaginates in the area of the Golgi apparatus. Additional membrane‐lined channels form within the nucleus as the Golgi apparatus separates and moves toward opposite spindle poles. Microtubules appear within the channels and make contact with distinct kinetochore‐like structures on the cytoplasmic side of the channels adjacent to the site of chromosome attachment. By mid‐mitosis two or three parallel channels dissect the nucleus perpendicular to the suture plane of the cell. Chromosome separation thus occurs perpendicular to the suture plane. An additional group of microtubules extends posteriorly from the flagellar apparatus towards the nucleus but has no apparent role in mitosis. Mitosis in P. minimum is compared to that of P. micans and to other dinoflagellates.
Flagellar Adherence of Crithidia fasciculata Cells in Culture1
Authors: HUGHES DALLAS , SIMPSON LARRY , SCHNEIDER CAROL AKAWIE
Published: May 2007

In early log phase cultures of several of the drug‐resistant mutants of Crithidia fasciculata that we have previously obtained, a high percentage of cells attach in pairs at the base of the flagellum. This process, which we have termed “flagellar adherence,” lasts for several hours in some cases and occasionally involves changes in cell morphology. The attachment occurs optimally in gently agitated cultures. Flagellar adherent pairs can be disassociated by vigorous agitation; the pairs reappear in the culture within one to three h after disassociation. These paired forms can be clearly distinguished from the normal cell division forms. Clones of flagellar adherent‐competent mutant strains are uniformly able to form these pairs in culture. A low percentage of flagellar adherent forms can be induced in wild type cells by glucose starvation.
Stage‐Dependent Effects of Chloroquine on Plasmodium falciparum In Vitro1
Authors: YAYON AVNER , WAA JOHN A. VANDE , YAYON MALKA , GEARY TIMOTHY G. , JENSEN JAMES B.
Published: May 2007

The erythrocytic developmental cycle of Plasmodium falciparum can be conveniently divided into the ring, trophozoite, and schizont stages based on morphology and metabolism. Using highly synchronous cultures of P. falciparum, considerable variation was demonstrated among these stages in sensitivity to chloroquine. The effects of timed, sequential exposure to several clinically relevant concentrations of chloroquine were monitored by three techniques: morphological analysis, changes in the rate of glucose consumption, and changes in the incorporation of 3H‐hypoxanthine into parasite nucleic acids. All three techniques gave essentially identical results. The trophozoite and schizont stages were considerably more sensitive to the drug than ring‐stage parasites. Chloroquine sensitivity decreased as nuclear division neared completion. The increase in chloroquine sensitivity was coincident with a marked rise in the rate of glucose consumption and nucleic acid synthesis. The rate of nucleic acid synthesis decreased as schizogony progressed while glucose consumption continued at high rates during this process. The degree of chloroquine sensitivity was not highly correlated with either metabolic activity.
Effect of Gossypol upon Motility and Ultrastructure of Trypanosoma cruzi1
Authors: BLANCO ANTONIO , AOKI AGUSTIN , MONTAMAT ENRIQUE E. , ROVAI LEONOR E.
Published: May 2007

Gossypol, a polyphenolic compound from the cotton plant, immobilizes and structurally alters cultured Trypanosoma cruzi epimastigotes. Ultrastructural changes observed in gossypol‐treated parasites were first detected in the kinetoplast and mitochondrion. At 50 μM concentration, much disorganization was evident after 5 min of incubation. With 25 μM gossypol, the same effect occurred after 30 min. Most epimastigotes were rounded, containing various membranous structures that could not be related to known cell components.
The Spread of Infection by the Microsporidan, Nosema disstriae, in Insect Cell Lines1
Authors: KURTTI TIMOTHY J. , TSANG K. ROGER , BROOKS MARION A.
Published: May 2007

Nosema disstriae, a parasite of the forest tent caterpillar, Malacosoma disstria, was cultured with cell lines UMN‐MDH‐1 (Malacosoma disstria), IPLB‐1075 (Heliothis zea), and BTC‐32 (Triatoma infestans). Infected cultured cells were used to infect the healthy cell lines. Electron micrographs of thin sections of 6‐day‐old cultures revealed infected cells that exocytosed vesicles containing vegetative and immature sporulating forms of the parasite. Some of these forms were believed to be responsible for intercellular transmission of the parasite. The spread of infection was augmented by culturing the cells at high densities; if the density was too low, there was little or no cross infection. Cross infection was inhibited, but not blocked completely, by high osmolality of the culture medium. The yield of spores from a confluent cell monolayer at the end of growth was generally 1–4 × 107 per ml of culture medium.
Immunofluorescent Localization of Myosin at the Anterior Pole of the Coccidian, Toxoplasma gondi1
Authors: SCHWARTZMAN JOSEPH D. , PFEFFERKORN E. R.
Published: May 2007

Indirect immunofluorescence using anti‐myosin rabbit sera showed myosin localized in a characteristic pattern at the anterior pole of Toxoplasma gondii. This polar fluorescent staining was abolished by pre‐absorption of the anti‐sera with myosin extracted from avian muscle. Both intracellular and extracellular T. gondii showed similar patterns when formaldehyde‐fixed, but neither showed polar fluorescence when acetone was used as the sole fixative. Immunofluorescent staining of live T. gondii revealed no polar fluorescence, suggesting that myosin is not present on the outer parasite membrane. Anti‐myosin serum did not prevent host cell invasion and plaque formation in the presence of human complement. Inhibition of contractile proteins with cytochalasin D inhibited T. gondii motility and infectivity in a plaque formation assay. The pattern of polar fluorescence described here resembles the IgM‐associated polar staining frequently detected in human sera, but we believe it is a different phenomenon because human sera that showed such staining retained their activity after pre‐absorption with avian myosin. The unusual localization of myosin at the anterior pole of T. gondii tachyzoites may play a role in the function of anterior organelles, which are thought to facilitate the invasion of host cells.
Actin in Tetrahymena paravorax: Ultrastructural Localization of HMM‐Binding Filaments in Glycerinated Cells1,2
Authors: MÉTÉNIER GUY
Published: May 2007

Actin has been identified in the ciliated protozoon Tetrahymena paravorax on the basis of the ultrastructural detection of filaments typically decorated with heavy meromyosin (HMM) in glycerinated microstome cells. These filaments are widely distributed in endoplasmic and cortical regions and can form bundles. They are particularly numerous in elongating cells; HMM‐binding filaments run approximately parallel to rib microtubules in the ectoplasm of the right wall of the buccal cavity and seem to extend to the cytopharyngeal region, suggesting some role of actin in maintenance of the crest‐trough pattern of ribbed wall and/or in formation of food vacuoles. Extensive actin bundles are observed below some membranellar areas and are thought to follow the course of the microtubular “deep fiber bundle.” The “fine filamentous reticulum” underlying the oral ribs and the “apical ring” extending beneath kinetosomes of ciliary couplets display filaments that do not bind HMM and are ˜ 14 nm in diameter. No evidence for actin in these structures was obtained in the present study. The “specialized cytoplasm” of the cytostome‐cytopharyngeal region appears as an undecorated reticulum with 20 nm‐spaced nodes. Occasionally HMM‐binding filaments were found inside the macronucleus, just beneath its envelope. Actin is suggested to be involved in cell shaping and in control of the transport of food vacuoles.
Transmission Electron Microscopy of Meront Development of Eimeria vermiformis Ernst, Chobotar and Hammond, 1971 (Apicomplexa, Eucoccidiorida) in the Mouse, Mus musculus1
Authors: ADAMS JOHN H. , TODD KENNETH S.
Published: May 2007

First and second generation meronts of Eimeria vermiformis developed in epithelial cells of the crypts of Lieberkühn. They were usually between the host cell nucleus and the basement membrane. Sporozoite organelles dedifferentiated with the first generation meront's development except for the refractile body and the apical complex, which persisted. After several nuclear divisions, the apical complex dedifferentiated further until only micronemes remained attached by a duct system to the plasmalemma. The form of the apical complex was highly variable. Sometimes the duct system was absent and the micronemes were attached directly to the plasmalemma or a dense material on it. Crescent body‐like material was often present in the parasitophorous vacuole next to the microneme structure. The microneme structure was not present in second generation meronts but evaginations of the plasmalemma, cytoplasmic outpocketings, and cytoplasmic vesicles were associated with the round granular bodies in the parasitophorous vacuoles. During first generation merogenesis, invaginations from the parasitophorous vacuole formed channels into the meront along which merozoites budded. Micropores were often at the ends of these invaginations. These and other micropores of the meront had a dense U‐shaped band for a collar while those of the merozoites had a collar with a double band of dense material that connected to the inner membrane. First generation merozoites budded randomly from the meront, resulting in a residual body that was usually in the middle of the parasitophorous vacuole. Second generation merozoites budded in one direction, resulting in a peripheral residual body and merozoites that were parallel in an oblong parasitophorous vacuole.
In Vitro Excystation of Caryospora simplex (Apicomplexa: Eimeriorina)1
Authors: UPTON STEVE J. , CURRENT WILLIAM L. , BARNARD SUSAN M. , ERNST JOHN V.
Published: May 2007

In vitro excystation of sporozoites of the heteroxenous coccidian Caryospora simplex Léger, 1904 (Apicomplexa: Eimeriorina) is described. Sporocysts freed mechanically from oocysts released a maximum of 51% of their sporozoites within 45 min at 25°C and a maximum of 74% within 20 min at 37°C when incubated in a 0.25% (w/v) trypsin–0.75% (w/v) sodium taurocholate (bile salt) excystation solution. At emergence from sporocysts, sporozoites were weakly motile then became highly active after about 2 min in excystation solution. Sporozoites within sporocysts exposed to bile salt only became highly motile within 25 min at 25°C and within 15 min at 37°C but did not excyst. When exposed only to trypsin at the above temperatures, the Stieda body dissolved; the substieda body remained intact, and the sporozoites exhibited only limited motility within sporocysts; only a few excysted. Intact, sporulated oocysts incubated at 25° or 37°C in 0.02 M cysteine‐HC1 and a 50% CO2 atmosphere for 18 h had no morphologic changes in the oocyst wall. Further incubation of these intact oocysts in excystation solution for 30 min at 37°C caused neither motility of sporozoites within sporocysts nor excystation. Grinding oocysts for 30 sec in a motor‐driven, teflon‐coated tissue grinder caused motility of some sporozoites within sporocysts but did not result in excystation.
Characteristics of Cytidine Aminohydrolase Activity in Trypanosoma cruzi and Crithidia fasciculata1
Authors: KIDDER GEORGE W.
Published: May 2007

Cytidine deaminase (cytidine aminohydrolase, 3.5.4.5) is present in Crithidia fasciculata (a mosquito parasite) and in Trypanosoma cruzi (a human pathogen). The enzyme from C. fasciculata deaminated both cytidine and deoxycytidine, the affinity for the former being much lower than the latter. Affinities for both substrates are equal for the T. cruzi enzyme. The production of the enzyme in C. fasciculata was significantly stimulated by the addition of a number of pyrimidine nucleosides (cytidine, uridine, 5‐bromouridine, thymidine, orotidine) to the culture media. Only cytidine stimulated enzyme production in T. cruzi. The enzyme from both organisms was unstable in air, even in the frozen state. Stabilization was achieved under anaerobic conditions.
Inhibitory Effect of Rhodamine 123 on the Growth of the Rodent Malaria Parasite, Plasmodium yoelii1
Authors: TANABE KAZUYUKI
Published: May 2007

The effect of the cationic permeant fluorescent dye, rhodamine 123 (R123), on the in vivo growth of Plasmodium yoelii was examined. Plasmodium yoelii‐infected mouse erythrocytes were incubated in vitro with R123 and injected intravenously into mice. Examination of daily parasitemias showed that R123 delayed parasite growth whereas rhodamine 110, a neutral compound, and fluorescein, a negatively charged fluorescent dye, did not. Infected erythrocytes treated with R123 were not cleared from the circulation even 7 h after injection. Quantitation of cell‐associated R123 by spectrophotometry revealed that infected cells with increased levels of R123 considerably prolonged the 2% prepatent period, the time required for the parasite to develop a 2% parasitemia. Degenerating parasites within and outside the host erythrocytes were observed on day 1 of infection in the mice. Thus it follows that R123, which accumulated in infected erythrocytes, inhibits the growth of P. yoelii; moreover, when R123‐labeled infected erythrocytes were treated with 1–10 μM carbonylcyanide m‐chlorophenylhydrazone (CCCP), a proton ionophore, to release R123 from the cells, the inhibitory effect on the growth rate of P. yoelii was partially reversed.
A Comparative Study of 14 Strains of Naegleria australiensis Demonstrates the Existence of a Highly Virulent Subspecies: N. australiensis italica n. spp.1
Authors: JONCKHEERE JOHAN F. DE , PERNIN PIERRE , SCAGLIA MASSIMO , MICHEL ROLF
Published: May 2007

Fourteen strains of Naegleria australiensis, including the type strain, were compared for virulence for mice, maximum growth temperature, lectin agglutination, isoenzyme pattern, and total protein banding pattern. Their relation to other species of Naegleria also was compared by immunoelectrophoretic analysis. Strains with high virulence, comparable to that of N. fowleri, were found to be different in concanavalin A agglutination as well as with regard to zymograms and total protein patterns. Although serologically different from N. fowleri and reacting with N. australiensis antiserum in the fluorescent antibody test, these high‐virulence strains differed in number of immunoelectrophoretic precipitin bands. Because of these results, the high‐virulence strains are considered to be a subspecies of N. australiensis. The low‐virulence strains showed minor differences from the type strain. Thus, N. australiensis does not appear to be as homogenous a species as N. fowleri. Pathogenic N. australiensis also seems to be more widespread than previously thought.
Changes in Oral Apparatus Structure Accompanying Vacuolar Formation in the Macrostomal Form of Tetrahymena vorax. A Model for the Formation of Food Vacuoles in Tetrahymena1
Authors: SMITH‐SOMERVILLE HARRIETT E. , BUHSE HOWARD E.
Published: May 2007

The large cytopharyngeal pouch of the macrostomal form of Tetrahymena vorax, following the addition of calcium, can form a sealed, empty vacuole. The open cytostomal region of this cell, which averages about 16 μ in diameter, is closed by an upward (ventral) movement of the right and posterior ribbed walls, both of which project into the cytostomal cavity. At the same time, the anterior and left walls of the cytostome‐cytopharyngeal complex move to the right, forming a diagonally (right to left) placed furrow in the floor of the buccal cavity as these walls meet. As a result of the movement, the edges of the single membrane‐bounded cytopharyngeal pouch are brought together and fuse, producing the closed vacuole. Elements of the cytoskeleton appear to participate in the closure process. Three major groups of ribbed wall microtubules support the open cytostome. The anterior ribbed wall microtubules pass laterally along the anterior (dorsal) portion of the cytopharyngeal pouch to the left where they end in the specialized cytoplasm. Middle oral rib microtubules terminate at the right and posterior margin of the cytopharynx while microtubules from the most posterior region of the ribbed wall pass to the left terminating in the specialized cytoplasm. The fine filamentous reticulum, a striated reticulum that borders the right, posterior, and anterior margins of the cytostome‐cytopharyngeal complex, is in an ideal position to participate in these movements. It is anchored anteriorly high up in the buccal cavity to the cross‐connective between the third membranelle and the undulating membrane complex. It courses beneath the right and posterior ribbed walls and runs laterally along the anterior margin of the cytopharynx to the left side. Contraction or pulling of this reticulum would act to bring the microtubule‐reinforced walls of the cytopharynx together permitting fusion of the cytopharyngeal pouch membranes to form a sealed vacuole.
Life Cycle of Culicosporella lunata (Hazard & Savage, 1970) Weiser, 1977 (Microspora) as Revealed in the Light Microscope with a Redescription of the Genus and Species1
Authors: HAZARD EDWIN I. , FUKUDA TOKUO , BECNEL JAMES J.
Published: May 2007

Light microscopy studies of Culicosporella lunata (Hazard & Savage), a parasite of the mosquito Culex pilosus (Dyar & Knab), revealed two sporogonial sequences. One sequence begins with diplokaryotic meronts that undergo repeated nuclear divisions to produce sporogonial plasmodia with nuclei in diplokaryotic arrangement. These plasmodia form rosette‐like clusters of sporoblasts during incomplete cytokinesis and, eventually, binucleate spores. These spores initiate infections in healthy larvae when they ingest spores. The second sequence begins with diplokaryotic meronts that undergo karyogamy and meiosis to form Thelohania‐like sporonts and haploid spores. Anomalies are often observed in these sporonts which result in aberrant spores, usually fewer than eight, in an accessory (pansporoblastic) membrane. Normal haploid spores are morphologically similar to those of species of Amblyospora. The genus and the type species are redefined based on new information presented here and it and the type species are placed in the family Amblyosporidae.
New Observations on Gametogenesis, Fertilization, and Zygote Transformation in Plasmodium gallinaceum1
Authors: AIKAWA MASAMICHI , CARTER RICHARD , ITO YOSHIHIRO , NIJHOUT MARY M.
Published: May 2007

The ultrastructure of the sexual stages of Plasmodium gallinaceum during gametogenesis, fertilization, and early zygote transformation is described. New observations are made regarding the parasitophorous vacuole (PV) of gametocytes and the process of emergence in male and female gametocytes. Whereas female gametocytes readily disrupted both the PV membrane and host cell plasmalemma during emergence, male gametocytes frequently failed to break down the plasmalemma of the host cell. New observations and hypotheses are presented on the behavior of the male gamete nucleus. Following fertilization, the male nucleus appears to travel through a channel of endoplasmic reticulum in the female gamete before fusing with the female nucleus at a region in which the nuclear envelope is thrown into extensive convoluted folds. Polarization of the zygote nucleus, in association with the appearance of a perinuclear spindle of cytoplasmic microtubules, preceded all other changes in the developing zygote. After nuclear polarization becomes apparent, electron‐dense material is deposited beneath the zygote pellicle, and a canopy is formed which eventually extends over the entire apical end of the developing ookinete. As the apical end begins to extend outward, polar rings, micronemes, and subpellicular microtubules become visible in this portion and a “virus‐like” inclusion known as a crystalloid is formed in the posterior portion of the zygote. When female gametes are prevented from being fertilized, the cytoplasm at 24 h after gametogenesis is devoid of most of those organelles found in the developing zygote or the mature ookinete. The cell is surrounded only by a single membrane. Although at various points beneath the membrane there are deposits of electron‐dense material reminiscent of those deposited in the zygote, no further development of ookinete structures takes place in the unfertilized female gamete.
Sporogony in Pneumocystis carinii: Synaptonemal Complexes and Meiotic Nuclear Divisions Observed in Precysts1
Authors: MATSUMOTO YOSHITSUGU , YOSHIDA YUKIO
Published: May 2007

Evidence for meiosis was demonstrated electron microscopically for the first time in Pneumocystis carinii in rat alveoli by the observation of synaptonemal complexes followed by nuclear divisions. Synaptonemal complexes indicating meiotic nuclear divisions were observed in uninuclear precysts. Additionally, owing to the use of tannic acid as a fixative, spindle microtubules were also observed for the first time in the precyst. Based on these facts, a new life cycle of the organism is proposed. The precyst has generally been considered an intermediate form between the trophozoite and the cyst. The present paper proposes that the precyst is additionally defined as the cell in which eight intracystic bodies are produced through meiotic reduction. The most characteristic feature of the precyst is a clump of mitochondria in the cytoplasm. We divide the precyst phase into three forms, which are named early, intermediate, and late. Synaptonemal complexes were only observed in the early precyst, which is a uninuclear cell with a thin pellicle. In the intermediate precyst, nuclear divisions are observed as follows: meiosis I produces two haploid nuclei and each of these divides at meiosis II producing four nuclei. After that, another postmeiotic mitosis takes place, resulting in eight haploid nuclei. In the late precyst, a delimiting membrane originates from the mother plasmalemma and surrounds the daughter nuclei and a small portion of the adjacent cytoplasm. Finally, when the eight intracystic bodies are complete, the precyst changes to a cyst. Thus, we deduce that intracystic bodies resulting from meiotic nuclear division are haploid and, after excystation, they are haploid trophozoites. We consider that this process can be called sporogony. Although we could not distinguish between the haploid and the diploid trophozoite, it is quite plausible that copulation occurs, probably in host alveoli.
The Ultrastructure of the Freshwater, Colorless Dinoflagellate Peridiniopsis berolinense (Lemm.) Bourrelly (Mastigophora, Dinoflagellida)1,2
Authors: WEDEMAYER GARY J. , WILCOX LEE W.
Published: May 2007

The ultrastructure of the freshwater, heterotrophic dinoflagellate Peridiniopsis berolinense (Lemm.) Bourrelly resembles other dinoflagellates in the structure of its nucleus, theca, flagella, and mitochondria. Other features less frequently reported in related organisms include fine sub‐sulcal fibers, collared pits in the flagellar base region, and unusual structures herein termed fibrillar lamellae. Numerous vesicles are present, some of whose contents are distinctly crystalline, while others contain what appears to be membranous material arranged in either whorls or parallel stacks; still other vesicles contain electron‐dense, granular spheres. Of particular interest is the transitional helix present in the longitudinal flagellum, this being the first report of such a structure among the dinoflagellates. Plastids of any kind are lacking, and a peduncle is present and is used during phagotrophy.
Cytochemical and Electrophoretic Studies on the Cyst Wall of a Ciliate, Histriculus muscorum Kahl
Authors: MATSUSAKA TADAO , HONGO FUMIKAZU
Published: May 2007

ABSTRACTM

The localization of proteins and polysaccharides in the cyst wall of a ciliate, Histriculus muscorum, was examined by light and electron microscope cytochemistry and by using an enzyme digestion test on thin sections. The endocyst and ectocyst were digested by treatment with pepsin or protease VI. The endocyst was intensely PAS‐positive and alcian blue‐positive. The ectocyst was also PAS‐ and alcian blue‐positive, but the reaction was weaker than that of the endocyst. At the electron microscope level, an intensely positive reaction to methenamine silver was observed in the endocyst and a weak reaction in the ectocyst of the mature cyst. In the ectocyst of the encysting organism, however, the reaction to methenamine silver was more intense than that of the mature cyst. These results demonstrate the possible presence of glycoproteins in the ectocyst and endocyst. The mesocyst was negative to all cytochemical and enzyme digestion tests examined. The cyst wall, isolated by sonication, was analyzed by SDS‐polyacrylamide gel electrophoresis. Two bands, 190 and 140 kilodaltons, were specific for the cyst wall. The 190 kilodalton band was the only PAS‐positive band and its localization in the cyst was was discussed.
The Ecology of Antigenic Variation1,2
Authors: SEED JOHN R. , EDWARDS ROBERT , SECHELSKI JOHN
Published: May 2007

A detailed molecular analysis using recombinant DNA technologies is extremely important to our understanding of the phenomena of antigenic variation in the African trypanosomes; however, by itself, it may not completely explain antigenic variation as it occurs in vivo. Several laboratories have demonstrated the ability of one variant population to replace another in vivo as well as the presence of heterogeneous populations of trypanosomes within an individual animal. These two phenomena do not permit us to explain antigen variation solely on the basis of the molecular regulation of variant antigen expression. In addition to studies in molecular biology, it will be necessary to define clearly the differences in growth rates of variant populations and the role of competition between these variants in a single anatomical site. It will also be necessary to determine the influence of various physiological environments on growth rates and the competition between the different variants of a single repertoire. It is concluded that the phenomenon of antigenic variation is a complex problem in ecology and population dynamics as well as molecular regulation. This paper is designated to examine a variety of the ecological parameters presumably involved in antigenic variation.
Antigenic Similarity Between the Coccidian Parasites Toxoplasma gondii and Hammondia hammondi1
Authors: ARAUJO FAUSTO G. , DUBEY J. P. , REMINGTON JACK S.
Published: May 2007

The antigens that are present in the coccidian parasites Toxoplasma gondii and Hammondia hammondi were demonstrated and defined by using SDS‐PAGE and immunoenzymatic techniques with 125I‐labeled and unlabeled antigens of T. gondii and sera of mice infected orally or intraperitoneally with H. hammondi. All cell surface antigens of T. gondii that were labeled with 125I were recognized by antibodies in the sera of the mice infected with H. hammondi except the antigen of approximate molecular weight of 21.5 Kd. This suggests that this antigen is specific for T. gondii. Various antigens in the T. gondii‐lysed antigen preparations were recognized by antibodies to H. hammondi. The number of recognized antigens increased as the infection of the mice with H. hammondi progressed. Oral infection with H. hammondi appeared to induce the formation of antibodies that recognized more T. gondii antigens than infection by intraperitoneal inoculation.
Complete Development of Isospora suis of Swine in Chicken Embryos1
Authors: LINDSAY DAVID S. , CURRENT WILLIAM L.
Published: May 2007

Development of the swine coccidium, Isospora suis, in embryonated chicken eggs is described. The allantoic cavities of eight‐to‐ten‐day‐old white Leghorn embryos were inoculated with either 100,000 or 200,000 sporozoites. Developmental stages morphologically similar to those found in the intestines of piglets were present in the endodermal layer of the chorioallantoic membrane (CAM), beginning three days post inoculation (PI). No stages were found in the mesodermal or ectodermal layers of the CAM and none were observed in heart, lung, liver, or spleen. Type I meronts and merozoites were found on days 3 through 10 PI. Type II meronts and merozoites were found days 4 through 10 PI. Mature microgamonts, macrogamonts, and oocysts were found on days 7 through 10 PI. Oocysts appeared to be retained in the endodermal cells and in ovo sporulation did not occur. Attempts to sporulate CAM‐derived oocysts were not successful. Isospora suis was not pathogenic for embryos under the conditions of this study. This study represents the first fully documented report of complete development of a mammalian coccidium in chicken embryos.
Absence of α‐Ketoglutarate Dehydrogenase Activity and Presence of CO2‐Fixing Activity in Plasmodium falciparum Grown In Vitro in Human Erythrocytes1
Authors: BLUM J. J. , GINSBURG H.
Published: May 2007

Plasmodium falciparum‐infected human erythrocytes grown in vitro do not release 14CO2, when incubated in the presence of [1‐14C]glutamate, despite the presence of glutamate dehydrogenase, implying the absence of α‐ketoglutarate dehydrogenase activity and the lack of functional tricarboxylic acid cycle in the human malaria parasite. Cultures incubated with [14C]bicarbonate, however, fix CO2 into acid‐stable metabolites; CO2 fixation proceeds linearly for up to two hours after an initial brief lag and may contribute appreciably to the metabolism of the parasite.
Phytohemagglutinin Induces Delays in Oral Regeneration in the Ciliate Stentor coeruleus1
Authors: MALONEY MICHAEL S.
Published: May 2007

Regenerating Stentor, exposed to the plant lectin phytohemagglutinin, are significantly delayed in completing oral regeneration. All of the delays are restricted to the earliest stages of regeneration prior to stage 3. The effects of phytohemagglutinin are reversible once the drug is removed. The addition of the presumed sugar receptor for phytohemagglutinin, N‐acetylgalactosamine, at the start of oral regeneration could not reverse the effects of phytohemagglutinin, but the addition of excess (10 mM) extracellular calcium could. When the addition of the excess calcium was delayed for various times after phytohemagglutinin exposure, the effectiveness of the calcium in reversing the phytohemagglutinin‐induced delays was reduced. Based on the mechanism of action of PHA in other cells, these results suggest that membrane proteins may be involved in controlling oral regeneration, possibly through mechanisms involving Ca++.
Temperature‐Dependent Spore Dimorphism in Burenella dimorpha (Microspora: Microsporida)
Authors: JOUVENAZ D. P. , LOFGREN C. S.
Published: May 2007

Burenella dimorpha, a microsporidian parasite of the tropical fire ant, Solenopsis geminata, produces two morphologically distinct types of spores. The binucleate free spores (spores not bound by a pansporoblast membrane) develop normally at temperatures at least as low as 20°C and as high as 32°C. The uninucleate octospores (spores bound in octets by a pansporoblast membrane), however, develop in a restricted range of temperature. Octospores constituted 35.9%± 2.6 of the spores in 25 pupae held at 28°C. Raising the temperature to 30°C reduced octospores to < 1% of the total spore population. Lowering the temperature to 25° or 22°C reduced the octospore population to 8.5%± 6.5 or 0.4 ± 0.5, respectively. Inhibition of octospore development was complete at 20°C. In contrast, the octospores of Vairimorpha necatrix and Vairimorpha plodiae are reported to be abundant at 16°C and 21°C, respectively. The critical event blocked in octospore development may be meiosis, as evidenced by an abundance of binucleate sporonts in the octospore sequence of development, and absence of more advanced sporogonic stages in hosts held at inhibitory temperatures. Free spore size is not affected by temperature although yield may be slightly reduced at elevated temperature.
The Death of an Amoeba1
Authors: LEITH A. G.
Published: May 2007

A geneological study shows that about 4% of the cells in healthy, adequately fed Amoeba proteus cultures are inviable. Two different categories of inviability are distinguished. About 44% of all inviability involves twin sisters formed at a division. Another 39% involves single cells with viable sisters and nieces. The inviable singles usually die more rapidly and show fewer visible abnormalities than the twins. The mothers of inviable twins show an increased interdivision time compared to mothers of inviable singles. Both categories of death are more rapid than starvation. The 17% of the deaths which involve aunt‐niece pairs appear to be special cases of twin sister or single cell deaths. There is no evidence for stem line division where a cell forms only one viable daughter for several generations. It is proposed that death is a normal occurrence in amoeba populations. It occurs regardless of culture conditions and may be a measure of accumulated lethal mutations in an asexual polyploid organism.
Parasitic Protozoa of the Blood of Rodents VI. Two New Hemogregarines of the Pygmy Flying Squirrel Idiurus macrotis (Rodentia: Theridomyomorpha: Anomaluridae) in West Africa
Authors: KILLCK‐KENDRICK R.
Published: May 2007

ABSTRACT. Descriptions are given of two new species of Hepatozoon Miller, 1908 found in the pygmy squirrel, Idiurus macrotis, in the Ivory Coast. Gamonts of both are parasites of monocytes.

The size and shape of the gamonts of one, H. normani n. sp., are similar to those of a number of gamonts of other species of rodent hemogregarines and the separate identity of the parasite is based on the host restriction of mammalian hemogregarines. The gamonts of the other species, H. dolichomorphon n. sp., are remarkably long and slender and are unlike those of any other known hemogregarine of mammals. Schizonts of this species were found in a smear prepared from heart blood.
Nonvariant Antigens Limited to Bloodstream Forms of Trypanosoma brucei brucei and Trypanosoma brucei rhodesiense1
Authors: BEAT DAVID A. , STANLEY HAROLD A. , CHOROMAŃSKL LESZEK , MacDONALD A. BRUCE , HONIGBERG B. M.
Published: May 2007

ABSTRACT. The presence of nonvariant antigens (NVAs) limited to bloodstream forms of Trypanosoma brucei brucei and Trypanosoma brucei rhodesiense was demonstrated for the first time by immunodiffusion and Immunoelectrophoresis. Noncloned and cloned populations were employed in preparation of polyclonal antisera in rabbits and of antigens to be used in the immunologic reactions. The NVAs could be shown best in systems in which hyperimmune rabbit sera (adsorbed with procyclic forms to eliminate antibodies against antigens common to bloodstream form and procyclic stages) were reacted with trypanosomes characterized by heterologous variant‐specific antigens (VSAs).

The NVAs demonstrated in this study are very likely different from the common parts of VSAs. As has been suggested by experiments with living trypanosomes, at least a part of the NVAs appears to be located on the surface of the bloodstream forms. In these experiments involving the quantitative indirect fluorescent antibody test, the amount of fluorescence recorded for the heterologous system, i.e. ETat 5 trypanosomes incubated with anti‐AmTat 1.1 serum, equalled ∼3.0% of the fluorescence emitted by the AmTat 1.1 bloodstream forms treated with their homologous antiserum. Evidently, only small amounts of NVAs are present on the surfaces of T. brucei bloodstream forms.

In addition to the NVAs, the electrophoresis results suggested the presence of antigenic differences between procyclic stages belonging to different T. brucei stocks.
Ecologic Aspects of Protozoan Infections in Antarctic Fishes1
Authors: NOBLE ELMER R.
Published: May 2007

ABSTRACT. Plankton and fishes are abundant in Antarctic waters. Benthic invertebrates and fishes of the continental shelf are well‐known, but the abyssal benthos below the highly productive open ocean is largely unsampled. The fishes are adapted (with antifreeze properties) to temperatures that are often or always below the freezing points of their body fluids. All the major groups of helminth parasites are found in or on these fishes. The few records of protozoa include Cryptobia, haemogregarines, a monoflagellate, the myxosporan Neoparvicapsula, and (in this paper) Ceratomyxa. Myxidium, Zschokkella, and a coccidian. Most of the protozoa were obtained from nototheniid fishes. No protozoa and few, if any, other parasites were recovered from 173 midwater fishes collected from outside of the continental shelf. Differences in infections in different localities and depths are due to many ecologic factors needing much more study of their relations to parasitism. These factors include temperatures, salinities, densities of fish populations, food and feeding habits, migrations of adult and immature fishes, availability of potential intermediate hosts, and marine “snow.”
Processing of Digestive Vacuoles in Tetrahymena and the Effects of Dichloroisoproterenol1
Authors: Fok Agnes K. , Shockley Brenda U.
Published: May 2007

The digestive‐lysosomai system in Telrahymena has been extensively studied; however, the various vacuole stages and the existence of a required processing period prior to defecation have not been clearly denned, in this study the presence of such a required processing period and the rate of DV defecation in Tetrahymena thermophila were determined. Like the cycle in Paramecium. a digestive cycle in Tetrahymena consisted of two periods: the processing period was 45 min and the defecation period was ˜2 h, making the complete cycle ˜3 h. During the defecation period vacuole egestion followed the kinetics of a first‐order rate reaction and had a rate constant of 0.0187/min and a t1/2 of 37 min (82 min into the cycle). Using the naphthol AS‐TR phosphate‐hexazotized rosanilin method to visualize acid phosphatase activity at the light microscopic level, DVs became positive beginning at 10 min. The number of positive DVs increased to a maximum of 13% when DVs were 20‐min old and declined to 5‐7% beyond 30 min. Although dichloroisoproterenol (DCI) has been reported by others to stimulate vacuole defecation, we found it inhibited the defecation rate. The extent of inhibition depended on the age of the DVs when exposed to DCI. Vacuole formation was completely blocked in cells pre‐exposed to 40 μ DCI for only 10 min; however, upon further exposure, cells could recover from this inhibition. The time required for complete recovery increased with increasing DCI concentrations. If DCI was given to cells simultaneously with latex beads, it was found to exert a dose‐dependent inhibitory effect on DV formation. These results showed the heterophagic pathway of the digestive‐lysosomal system in Telrahymena to be similar to that of Paramecium, though it was less efficient in the former cell.
Isolation and Properties of Macronuclei from Tetrahymena thermophila1
Authors: Corr Reinhard , Eichler Wolfgang
Published: May 2007

A simple and efficient method is described for the isolation of macronuclei from Tetrahymena thermophila (7B). The steps involved are deciliation and removal of the mucocysts’ contents by dibucaine treatment, digitonin mediated lysis, differential centrifugations, and finally isopyenic sucrose density gradient centrifugation. Judging from the distribution of marker enzymes and electron microscopy, the macronuclei obtained were free of cytoplasmic and paniculate contamination and were highly active in endogenous RNA‐synthesis (1.5 pmol UTP incorporation/ng DNA min at 30°C). The ratio of protein: RNA: DNA was 2.0:0.33:1.0 (weight) and each macronucleus contained an average of 17 pg DNA. The average yield of isolation was 50%.