bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of the T, L, I, S, M and P Cell Surface (Immobilization) Antigens of Tetrahymena thermophila: Molecular Weights, Isoforms, and Cross‐Reactivity of Antisera
Authors: SMITH DEBORAH L. , BERKOWITZ MICHELE S. , POTOCZAK DOUGLAS , KRAUSE MARJORIE , RAAB CAROL , QUINN FRANK , DOERDER F. PAUL
Published: May 2007

ABSTRACT. In the ciliate protist Tetrahymena thermophila the L, H, T, I, S, M and P cell surface proteins (immobilization antigens) are expressed under different conditions of temperature (L, H, T), culture media (I, S), and mutant genotype (M, P). Immunoblot and autoradiographic studies using antisera to purified protein show that the molecular weights of these proteins range from 25,000 to 59,000. The H, T, S, M and P antigens are recognized as single polypeptides, whereas L, I, and one allelic form of T each appear to consist of a family of polypeptides. Although antisera are specific in immobilization and immunofluorescence assays of surface protein in living cells, cross‐reactivity is seen with denatured protein on immunoblots. It is hypothesized that the surface protein genes are organized into families of evolutionarily related isoloci.
Lysosomal Membrane Proteins of Amoeba proteus, as Studied with Monoclonal Antibodies
Authors: CHOI EUI Y. , KIM KEE J. , JEON KWANG W.
Published: May 2007

Monoclonal antibodies were prepared against lysosomal membrane proteins of amoebae and used to follow lysosome‐phagosome fusion after induced phagocytosis. The specificity of antibodies was checked by indirect immunofluorescence microscopy, immunoelectron microscopy, and localization of the antigen in subcellular fractions. The antibody‐recognized proteins started to appear on the membranes of phagolysosomes about 5 min after phagocytosis as detected by indirect immunofluorescence, and the intensity of fluorescence increased for up to 1 h. Results of injection experiments in which purified antibodies had been injected into living cells and probed by indirect fluorescence indicated that the antigens were located on the cytoplasmic side of the lysosomal membranes. Lysosomes fuse with phagosomes on the one hand but not with non‐fusible vesicles such as symbiosomes on the other. The results support the view that a membrane component(s) of non‐fusible vesicles somehow prevents lysosomoes from fusing with them.
Meiosis‐Reinitiation‐Inducing Factor of Tetrahymena Functions Upstream of M‐Phase‐Promoting Factor
Authors: FUJISHIMA MASAHIRO , KATSU YOSHINAO , OGAWA EISHI , SAKIMURA MASANORI , YAMASHITA MASAKANE , NAGAHAMA YOSHITAKA
Published: May 2007

Reinitiation of meiosis (maturation) of amphibian Bufo and Xenopus oocytes can be induced if Tetrahymena extract is injected into them. The activity differed from M‐phase‐promoting factor, because action of the former factor on the induction of maturation was inhibited by treatment of the oocytes with cycloheximide. Activity of M‐phase‐promoting factor was not detected in Tetrahymena extract regardless of the presence of cdc2 homologues in the extract. However, cycloheximide‐resistant‐maturation‐inducing activity appeared in the recipients, when the maturation was induced by injection of Tetrahymena extract. Immunoblots using antibodies against cdc2 showed that injection of Tetrahymena extract induced fast mobility of the recipient cdc2 in the presence of the recipient protein synthesis. The same mobility shift of the cdc2 was also induced when M‐phase‐promoting factor containing Xenopus oocyte extract was injected into immature oocytes or when the immature oocyte extract was treated with alkaline phosphatase. These results indicate that meiosis‐reinitiation‐inducing factor of Tetrahymena functions upstream of M‐phase‐promoting factor to induce dephosphorylation of the recipient cdc2. Tetrahymena cdc2 homologues also showed fast mobility when the Tetrahymena extract was treated with alkaline phosphatase. Preliminary experiments showed that the meiosis‐reinitiation‐inducing factor of Tetrahymena was a soluble protein.
Sporogonic Development of Leucocytozoon smithi
Authors: STEELE EDNA JOSEF , NOBLET GAYLE PITTMAN , NOBLET RAYMOND
Published: May 2007

The sporogonic development of Leucocytozoon smithi in its black fly vector was studied by light and electron microscopy and was compared with that of other haemosporidians. Within 18 to 24 h after ingestion of gametocytes by black flies, ookinetes passing through the midgut epithelium were observed. Intracellular migration of ookinetes resulted in the apparent disruption and degeneration of host cells. Intercellular migration also occurred as was evidenced by the presence of ookinetes between midgut cells. Transformation of ookinete to spherical oocyst occurred extracellularly in three different sites. Although most oocysts were found between the host cell basal membrane and the basal lamina, large numbers also were found attached to the external surface of the basal lamina, projecting into the hemocoel. Ectopic development of oocysts in the midgut epithelium between cells was observed much less frequently than development on the basal side of the midgut. The oocyst wall of dense granules, believed to be of parasite origin, was distinguishable from the basal lamina of the host's midgut epithelium. As in other Leucocytozoidae, the cytoplasm of the oocyst differentiated into a single sporoblastoid from which 30–50 sporozoites were formed. Beginning on the third day post infection, elongation of segregated dense sporoblastoid material associated with pellicle thickening led to the formation of the finger‐like sporozoite buds which projected into the oocyst cavity. Sporozoites within mature oocysts and salivary glands were structurally similar to sporozoites as described for other haemosporidians.
Discontinuous Genetic Variation Among Mesophilic Naegleria Isolates: Further Evidence that N. gruberi Is Not a Single Species
Authors: ROBINSON BRET S. , CHRISTY PETER , HAYES SUZANNE J. , DOBSON PHILIP J.
Published: May 2007

Naegleria isolates which are currently placed in the type species N. gruberi display great genetic, physiological and morphological heterogeneity. There are two possible interpretations of the nature of this species–that N. gruberi is a species complex or that it is a single continuously variable species. To distinguish between these alternatives, allelic states were determined for 33 loci in 74 new isolates selected to represent wide geographic sources and diverse temperature limits for growth. The results were compared with data for culture collection strains of N. gruberi and other species in the genus. The isolates formed a discontinuous series of clusters, separated by genetic distances similar to those separating the better‐characterised taxa N. fowleri, N. lovaniensis, N. jadini, N. australiensis australiensis and N. australiensis italica. Culture collection strains assigned to N. gruberi fell into six distinct clusters, while other clusters were not represented by reference strains. The data are most consistent with the interpretation that N. gruberi is a group of several distinct species, each equivalent to the recently described species in the genus. Naegleria andersoni andersoni and N. andersoni jamiesoni also formed two distinct clusters, equivalent to species. Characteristic temperature limits for growth show that the mesophilic species are ecological as well as genetic entities.
Penetration of the Mosquito (Aedes aegypti) Midgut Wall by the Ookinetes of Plasmodium gallinaceum
Authors: TORII MOTOMI , NAKAMURA KEI‐ICHIRO , SIEBER KLAUS P. , MILLER LOUIS H. , AIKAWA MASAMICHI
Published: May 2007

ABSTRACT We observed Plasmodium gallinaceum ookinetes in both intracellular and intercellular positions in the midgut epithelium of the mosquito Aedes aegypti. After epithelial cell invasion intracellular ookinetes lacked a parasitophorous vacuolar membrane and were surrounded solely by their own pellicle. Thus, the ookinete in the midgut epithelium of the mosquito differs from erythrocytic and hepatic stages in that the parasite in the vertebrate host is surrounded by a vacuole. The midgut epithelial cytoplasm around the apical end of invading ookinetes was replaced by fine granular material deprived of normal organelles. Membranous structure was observed within the fine granular area. Most ookinetes were seen intracellularly on the luminal side and intercellularly on the haemocoel side of the midgut epithelial cells. These observations suggest that the ookinete first enters into the midgut epithelial cell, then exits to the space between the epithelial cells and moves to the basal lamina where the ookinete develops to the oocyst.
Genotoxic Effects of Linear Alkyl Benzene Sulfonate, Sodium Pentachlorophenate and Dichromate onTetrahymena pyriformis
Authors: WU YUPING , SHEN YUNFEN
Published: May 2007

ABSTRACTDNA in macro‐ and micronuclei ofTetrahymena pyriformistreated with linear alkyl benzene sulfonate (LAS) and sodium pentachlorophenate (PCP‐Na) were determined by microspectrophotometry. The effects on rate of formation of macronuclear DNA extrusion bodies were also studied. We found DNA content of micronuclei in 0.14 ppm LAS and 0.9 ppb PCP‐Na was lower than in that of the control, and LAS was able to increase the formation rate of macronuclear DNA extrusion bodies (the formation rate was 54% in 11.3 ppm LAS and 25.6% in 16.7 ppm dichromate). We concluded that 0.14 ppm LAS (below the maximum acceptable toxicant concentration) was genotoxic, whereas 0.014 ppm LAS was not. Dichromate 0.05 ppm and 0.9 ppb PCP‐Na, equal to and below the maximum acceptable toxicant concentration, respectively, were potentially genetoxic.
Characteristics of a Microsporidium (Protozoa: Microspora) Infecting Grasshoppers (Orthoptera: Pyrgomorphidae) in Cape Verde, Africa
Authors: LANGE CARLOS E. , BRITO JORGE M. , HENRY JOHN E.
Published: May 2007

ABSTRACT A light and electron microscopic study was conducted of a microsporidium isolated from the grasshopper Pyrgomorpha cognata Krauss, 1877 collected in Santo Antão and Santiago Islands, Cape Verde. The evidence suggests that although there are some differences, such as tissues affected and size of spores, the organism appears conspecific with Nosema pyrgomorphae Toguebaye, Seck & Marchand, 1988, which was described from another species of the genus Pyrgomorpha Audinet‐Serville, 1838 in Senegal. However, in addition to the differences in tissue specificity and size of spores, light microscopy studies also revealed some stages of the pathogen (uninucleate bodies and plasmodia) apparently not previously observed in N. pyrgomorphae.
Sporulation of Marteilioides branchialis N. Sp. (Paramyxea) in the Sydney Rock Oyster, Saccostrea commercialis: An Electron Microscope Study
Authors: ANDERSON TIMOTHY J. , LESTER ROBERT J. G.
Published: May 2007

ABSTRACT The ultrastructure of sporulation of a new parasite, Marteilioides branchialis (Paramyxea), in the Sydney Rock oyster, Saccostrea commercialis, is described. The development is typical of other Paramyxea whereby a stem cell internally cleaves a secondary cell contained within a vacuole. It differs from other species in the phylum in that each secondary cell produces a single spore composed of two concentric cells, one within a vacuole of the other. This type of sporulation represents the simplest of all known Paramyxea. Infection results in focal gill lesions and was observed concurrently with an epizootic of another paramyxean, Marteilia sydneyi.
Giardia lamblia: Ultrastructural Study of the In Vitro Effect of Benzimidazoles
Authors: CHAVEZ BIBIANA , CEDILLO‐RIVERA ROBERTO , MARTINEZ‐PALOMO ADOLFO
Published: May 2007

ABSTRACT Axenically grown Giardia lamblia trophozoites treated with low concentrations of the benzimidazole carbamates albendazole and mebendazole detach from glass culture tubes and lose viability. Scanning electron microscopic observations revealed that these drugs produce grotesque modifications of the cell shape of the parasite and disassembly of the adhesive disc. Transmission electron microscopy showed several stages of the fragmentation of adhesive discs with dispersion of microtubules and microribbons in the cytoplasm. Flagella appeared undamaged. In drug‐treated trophozoites electron‐dense precipitates were selectively deposited on microtubules and microribbons. The results indicate that the antigiardial effect of benzimidazoles is the result of binding to microtubules and subsequent alterations of the cytoskeleton. The electron microscopic observations also suggest that the drugs may bind to microribbon components of the adhesive disc, possibly giardin proteins.
Plasmodium falciparum: Differential Sensitivity In Vitro to E‐64 (Cysteine Protease Inhibitor) and Pepstatin A (Aspartyl Protease Inhibitor)
Authors: BAILLY ERIC , JAMBOU RONAN , SAVEL JEAN , JAUREGUIBERRY GINETTE
Published: May 2007

ABSTRACT We investigated the effect of a cysteine proteinase inhibitor (E‐64) and an aspartyl proteinase inhibitor (Pepstatin A) on asexual erythrocytic stages of Plasmodium falciparum in culture. These two protease inhibitors showed different patterns of activity. E‐64 acted preferentially against trophozoite and schizont stages. After 48 h incubation at high concentrations of E‐64 (28, 140, 280 μM), growth was totally abolished and the parasites presented characteristic enlarged food vacuoles. Morphological alterations were also seen after shorter incubation periods (6 h at 28 μM) or 12 h at the inhibitory concentration 50% (12 μM), but an additional culture period (24 h) in inhibitor‐free medium allowed normal parasite development, demonstrating a parasitostatic effect. E‐64 acts on parasite multiplication; the normal merozoite maturation was altered and the normal reinvasion process partially impaired. Pepstatin A used at the inhibitory concentration 50% (4 μM) killed the parasites before trophozoite development and had a major effect on schizonts maturation. No altered parasite development occurred during an additional culture period without Pepstatin A, demonstrating a parasiticidal effect. E‐64 and Pepstatin A used in combination inhibit the parasite growth with a strong synergistic effect.
Eimerians in Harvest Mice, Reithrodontomys spp., from Mexico, California and New Mexico, and Phenotypic Plasticity in Oocysts of Eimeria arizonensis
Authors: DUSZYNSKI DONALD W. , PATRICK MICHAEL J. , COUCH LEE , UPTON STEVE J.
Published: May 2007

ABSTRACT Between May 1979 and August 1991, 48.7% (57/117) of the harvest mice (Reithrodontomys spp.) examined from 10 localities in Mexico, California and New Mexico had coccidian oocysts in their feces. A total of 46.7% (49/105) of the Reithrodontomys megalotis examined were positive for coccidian oocysts; this included samples from five states in Mexico (47.1%, 8/17), three counties in California (66.7%, 4/6) and two counties in New Mexico (45.1%, 37/82); 66.7% (8/12) of the Reithrodontomys montanus from one county in New Mexico also were infected. Only two coccidian species, Eimeria arizonensis and Eimeria langebarteli, were found in these hosts. Oocysts of E. langebarteli were found only in R. megalotis: in all three infected mice from Madera County, California, in the only mouse from San Bernardino County, California, and in 63% (5/8) of the infected mice from four states in Mexico. Oocysts of E. arizonensis were found in R. megalotis in Mexico, California, and New Mexico and in R. montanus from New Mexico. Sporulated oocysts of E. langebarteli differed slightly from those in previously published reports by having wider oocysts and larger sporocysts. Sporulated oocysts of E. arizonensis were variable in size, with those recovered from R. montanus significantly larger in length and width and sporocyst width than those from R. megalotis. The structure of the oocyst residuum was polymorphic, both within and between host species, and within the same mouse; it could appear as one large globule, two globules, several to many smaller globules, or as a compact mass of many small granules. Oocysts with a variable residuum were larger than those with one globule in all oocyst/sporocyst dimensions. Only 9% (5/57) of the infected mice were discharging oocysts of both eimerians when examined.
Exoerythrocytic Development of Plasmodium Gallinaceum Sporozoites In A Chicken Fibroblast Cell Line and Inhibition of the Cell Invasion By Specific Anti‐Sporozoite Monoclonal Antibodies
Authors: ROCHA ELIANA M. M. , HOLLINGDALE MICHAEL R. , GWADZ ROBERT , KRETTLI ANTONIANA U.
Published: May 2007

ABSTRACT. Cultivation of the Plasmodium gallinaceum exoerythrocytic forms from sporozoites was attempted in three diferent cell lines: HEPG2‐A16 (from a human hepatoma), VERO (monkey kidney epithelial cells) and SL‐29 (chicken embryo fibroblast cells). the sporozoites in vaded all three cell types but their development into exoerythrocytic forms ocurred only in the SL‐29 cells. In the presence of specific monoclonal antibodies against the major circumsporozoite protein, there were varying degrees of inhibition of parasite invasion of the SL‐29 cells. of seven monoclonal antibodies tested, two completely inhibited cell invasion at high concentrations and caused intense inhibition at concentrations as low as 2.5 μg/ml, four caused intense inhibition at these various concentrations, and one had no effect on sporozoite invasion.
DNA Fingerprinting of Trypanosoma vivax Isolates Rapidly Identifies Intraspecific Relationships
Authors: DIRIE MOHAMED F. , MURPHY NOEL B. , GARDINER PETER R.
Published: May 2007

ABSTRACT. Using the polymerase chain reaction and arbitrarily selected oligonucleotide primers of 10 or 11 bases, we have amplified DNA sequences from Trypanosoma vivax parasites isolated from South America and Africa. On the basis of polymorphisms in the DNA fingerprints generated by three of the primers, the parasites could be separated into two major groups, one comprising T. vivax isolates from Kenya and the second including all the other T. vivax parasites (from Colombia, The Gambia, Nigeria and Uganda). One of these three primers (ILo 525) also gave isolate‐specific DNA fingerprints for the parasites for the parasites tested, which will allow the use of this technique both in the species identification and discrimination of T. vivax parasites.
Nosema scripta N. Sp. (Microsporida: Nosematidae), A Microsporidian Parasite of the Cottonwood Leaf Beetle, Chrysomela scripta (Coleoptera: Chrysomelidae)1
Authors: BAUER LEAH S. , PANKRATZ H. STUART
Published: May 2007

ABSTRACT. Nosema scripta (Microsporida: Nosematidae), a new species of microsporidian parasite, is described from the cottonwood leaf beetle, Chrysomela scripta F. (Coleoptera: Chrysomelidae), in North America. Studies using light and electron microscopy reveal that this species completes its life cycle in direct contact with the cytoplasm of cells within the fat body, midgut, hindgut, muscles, central nerve cord, Malpighian tubules, tracheal end cells, and ovaries. the microsporidium is monomorphic, all life stages are diplokaryotic, and spores develop from disporous sporonts. The mature spores are broadly oval and measure 4.2 ± 0.10 times 3.4 ± 0.04 μm. Spores contain a tubular polar filament that is arranged peripherally in a single layer of 13‐15 coils. Both horizontal transmission and vertical transmission have been demonstrated for this microsporidium in C. scripta in the laboratory. The Colorado potato beetle, Leptinotarsa decemlineata (Say), was susceptible to infection with this pathogen in cross‐infectivity studies.
Effect of Low Temperature On the In Vitro Growth of Plasmodium falciparum
Authors: ROJAS MARÍA O. , WASSERMAN MOISÉS
Published: May 2007

ABSTRACT. The effect of low incubation temperature on synchronized cultures of Plasmodium falciparum was studied. Young trophozoites that were maintained at 28°C matured slowly and invaded poorly. Growth seemed to arrest when parasites reached a maturation equivalent to 30 h, although they reestablished their growth normally when returned to 37°C. On the other hand, 36‐h synchronized parasites that were transferred to 28°C completed their cell cycle with a 12‐16 h delay, but without changes in the parasite as seen by light microscopy and without a diminution in the efficiency of the invasion or in the incorporation of 35S‐methionine. These results might be useful for obtaining parasites at defined stages of development at the desired time.
Ultrastructural and Cytochemical Identification of Peroxisomes in the Ciliate Ichthyophthirius multifiliis
Authors: LOBO‐DA‐CUNHA ALEXANDRE , AZEVEDO CARLOS
Published: May 2007

ABSTRACT. The peroxisomes of the parasitic ciliate Ichthyophthirius multifiliis were studied, using ultrastructural and cytochemical techniques. In this ciliate most peroxisomes possess a circular or oval section less than 0.6 μm in diameter. However, some dumbbell‐shaped and elongated peroxisomes could also be observed. These organelles were frequently associated with the mitochondria and were more abundant in the cell cortex than in the center of the ciliate. Small vesicles and dense nucleoids were usually present in the ultrathin sections of these peroxisomes. Peroxisomal vesicles and tubular structures were selectively impregnated with osmium tetroxide. Catalase was detected by cytochemical techniques in I. multifiliis peroxisomes.
Developmentally‐Regulated Virulence Factors of Trypanosoma cruzi and Their Relationship to Evasion of Host Defences1
Authors: HALL B. FENTON , JOINER KEITH A.
Published: May 2007

ABSTRACT. Developmental preadaptation of virulent stages of Trypanosoma cruzi correlates with their ability to survive and establish infection in mammalian hosts. Infective trypomastigote stages must first preadapt to survival in the extracellular milieu and then to the rigors of establishing an intracellular infection. Selected phenotypic variations in evading host defences have been correlated with expression of stage‐specific proteins or functions. Resistance of trypomastigotes to complement‐mediated killing correlates with the presence of a stage‐specific molecule that exhibits an analogous function to mammalian decay‐accelerating factor, and with the presence of a neuraminidase/trans‐sialidase that transfers sialic acid moieties to the parasite surface, thereby enabling it to avoid complement activation. Trypomastigotes enter cells by a mechanism that involves sorting of cell surface receptors and avoids eliciting a respiratory burst. Once within a membrane‐bound vacuole, which undergoes acidification, the neuraminidase/trans‐sialidase and an acid‐active, transmembrane pore‐forming protein are released by the parasite and are capable of acting together to accelerate rupture of the vacuolar membrane and the parasite's escape into the cytoplasm of the host cell. Escape from the parasitophorous vacuole allows virulent stages of T. cruzi to avoid compartmental, non‐oxidative killing mechanisms such as degradation by lysosomal hydrolases.
Trypanosoma ManulisN. Sp. From the Russian Pallas CatFelis Manul
Authors: BARR STEPHEN C. , BOWMAN DWIGHT D. , PHILLIPS LYNDSEY G. , BARR MARGARET C.
Published: May 2007

ABSTRACT.The morphology ofTrypanosoma manulisn. sp. is described from living and stained specimens obtained from the blood of a Pallas cat,Felis manul, from Kazakhstan. the cat was also infected with aHepatozoonsp. and feline immunodeficiency virus. the morphology of the trypanosome most closely resembles that ofTrypanosoma mpapuenseReichenow andTrypanosoma heybergiRodhain found in bats.Trypanosoma manulisdoes not grow well in conventional media, but co‐culture with African green monkey kidney cells in Eagle's Minimum Essential Medium supplemented with 10% fetal calf serum at approximately 27° C resulted in luxuriant growth of trypanosomes. Under these growth conditions, epimastigotes adhered to the surface of the culture flask and to African green monkey kidney cells, as well as forming large rosettes. At 37° C, although growth was poor, transformation of the epimastigotes into the bloodstream forms occurred. This represents the first report of a trypanosome of the subgenusMegatrypanumin a felid.
The Isolation and Partial Characterization of A Babesia Sp. From Desert Bighorn Sheep (Ovis Canadensis Nelsoni)
Authors: GOFF WILL L. , JESSUP DAVID A. , WALDRUP KENNETH A. , THOMFORD JOHN W. , CONRAD PATRICIA A. , BOYCE WALTER M. , GORHAM JOHN R. , WAGNER GERALD G.
Published: May 2007

ABSTRACT. A novel Babesia parasite of desert bighorn sheep was isolated. Its taxonomic description, host range, pathogenicity and antigenic relatedness were in vestigated. the parasite was infective for black‐tailed and white‐tailed deer, but with host‐specific differences compared to that of bighorn sheep. A splenectomized calf and domestic sheep were refractory to infection. A comparative immunofluorescence assay detected antigens cross‐reactive with Babesia odocoilei, B. divergens, B. equi and B. caballi, but not with B. bovis or, B. bigemina. Babesia odocoilei was also infective for bighorn sheep, allowing comparison by a cross‐challenge experiment, the results of which supported the conclusion that this parasite was not B. odocoilei. However, the bighorn sheep Babesia cannot currently be distinguished from B. capreoli described from roe deer in northern Germany. Data indicate that, while this parasite may not present a problem for domestic animals, it may cause disease in bighorn sheep and deer populations.
Marine Heterotrophic Amoebae, Flagellates and Heliozoa From Belize (Central America) and Tenerife (Canary Islands), With Descriptions of New Species, Luffisphaera Bulbochaete N. Sp., L. Longihastis N. Sp., L. Turriformis N. Sp. and Paulinella Intermedia N. Sp.
Authors: VØRS NAJA
Published: May 2007

ABSTRACT. Thirty four taxa of heterotrophic protists (amoebae, flagellates and heliozoa) were encountered in cultures established from marine samples from Belize (Central America) and Tenerife (Canary Islands). Most species are flagellates drawn from the choanoflagellates, the cryptophyceans, the euglenids, the kinetoplastids, the bicosoecids, the chromulinids, the pedinellids and a variety of laxa of uncertain affinities (Protista incertae sedis). the identity of the thecate choanoflagellates Salpingoeca ringens Kent, 1880, and S. tuba Kent, 1880, is discussed, and four new species of heterotrophic protists are described: one new species of the amoeba genus Paulinella (Paulinella intermedia n. sp.) and three new species of the incertae sedis genus Luffisphaera Belcher & Swale, 1975 (Luffisphaera bulbochaete n. sp.; L. longihastis n. sp.; L. turriformis n. sp.).
Ribosomal Dna Sequences of Encephalitozoon Hellem and Encephalitozoon Cuniculi: Species Identification and Phylogenetic Construction
Authors: VOSSBRINCK CHARLES R. , BAKER MICHAEL D. , DIDIER ELIZABETH S. , DEBRUNNER‐VOSSBRINCK BETTINA A. , SHADDUCK JOHN A.
Published: May 2007

ABSTRACT. A segment of ribosomal DNA, about 1,350 base pairs long, was amplified from the microsporidian species Encephalitozoon hellem, isolated from AIDS patients, and Encephalitozoon cuniculi. the amplified DNA segment extends from position 530 in the small ribosomal RNA subunit to position 580 in the large ribosomal RNA subunit. A comparison of sequence data from this region for Encephalitozoon hellem and Encephalitozoon cuniculi shows relatively high sequence similarity, supporting the placement of these two organisms in the same genus. At the same time, sequence differences between the two organisms confirm that they are not the same species. Three separate isolates of E. hellem were sequenced in the highly variable intervening spacer region. the sequence was identical for all three isolates. Within the amplified DNA segment, regions were sequenced which yield highly variable, moderately variable and highly conserved sequence information, appropriate for comparison with other species in the phylum Microspora at all taxonomic levels. We suggest that sequence data from these regions be included in future species descriptions for the purposes of species identification and phylogenetic analysis. Restriction digests of the amplified region are presented and give a rapid method for distinguishing between the two Encephalitozoon species.
African Buffalo Serum Contains Novel Trypanocidal Protein
Authors: REDUTH DAGMAR , GROOTENHUIS JAN G. , OLUBAYO REARDON O. , MURANJAN MADHAVI , OTIENO‐OMONDI FREDERICK P. , MORGAN GRANT A. , BRUN RETO , WILLIAMS DIANA J. L. , BLACK SAMUEL J.
Published: May 2007

ABSTRACT. The high ability of African buffalo, as compared to domestic cattle, to control infections with Trypanosoma brucei brucei IL Tat 1.4 organisms did not correlate with the timing or magnitude of parasite surface coat‐specific antibody responses and may have resulted from the constitutive presence in buffalo blood of a novel trypanocidal factor. Buffalo plasma and serum contained material that killed bloodstream stage T. b. brucei, T. b. rhodesiense, T. b. gambiense, T. evansi, T. congolense, and T. vivax organisms during four h of incubation at 37° C in vitro. Serum from eland was also trypanocidal whereas serum from oryx, waterbuck, yellow‐back duiker, cattle, horse, sheep, goat, mouse, rat, and rabbit was not trypanocidal. The buffalo serum trypanocidal material was not lipoprotein, or IgG, and had the following properties: 1) a density of < 1.24 g/ml determined by flotation ultracentrifugation; 2) insolubility in 50% saturated ammonium sulphate; 3) non‐reactivity with anti‐bovine IgM, and anti‐bovine IgG; 4) non‐reactivity with protein G, and protein A; 5) a relative molecular mass of 152 kDa determined by chromatography on Sephacryl S 300, and of 133 kDa determined by chromatography of the 50% SAS cut of IgG‐depleted buffalo serum on Superose 12; 6) no associated cholesterol; and 7) inactivation by digestion with proteinase K that was immobilized on agarose.
The Uptake and Metabolism of Cysteine by Giardia lamblia Trophozoites
Authors: LUJAN HUGO D. , NASH THEODORE E.
Published: May 2007

ABSTRACT. The cysteine, cystine, methionine and sulfate uptake and cysteine metabolism of Giardia lamblia was studied. Initial experiments indicated that bathocuproine sulphonate (20 μM) added to Keister's modified TYI‐S‐33 medium supported the growth of G. lamblia at low L‐cysteine concentration. This allowed the use of high specific activity radiolabeled L‐cysteine for further studies. The analyses of L‐cysteine uptake by G. lamblia indicate the presence of at least two different transport systems. The total cysteine uptake was non saturable, with a capacity of 3.7 pmoles per 106 cells per min per μM of cysteine, and probably represent passive diffusion. However, cysteine transport was partially inhibited by L‐methionine, D‐cysteine and DL‐homocysteine. indicating that another system specific for SH‐containing amino acids is also present. Cysteine uptake was markedly decreased in medium without serum. In contrast to cysteine, the uptake of L‐methionine and sulfate were carried out by saiurable systems with apparent Km, of 71 and 72 μM, respectively, but the Vmax of the uptake of sulfate was six orders of magnitude lower than the Vmax of methionine uptake. Cystine was not incorporated into trophozoites. [35S]‐labeled L‐cysteine and L‐methionine, but not [35S]sulfate, were incorporated into Giardia proteins, indicating that the parasite lacks the capacity to synthesize cysteine or methionine from sulfate. Neither cystathionine γ lyase nor crystathionine γ synthase activities was detected in homogenates of Giardia lamblia, suggesting that the transsulfuration pathway is not active and there is no conversion of methionine to cysteine. Our data indicate that cysteine is essential for Giardia because the parasite: a) cannot take up cystine, and b) cannot synthesize cysteine de novo.
Two Distinct Varieties of Giardia in a Mixed Infection from a Single Human Patient
Authors: UPCROFT JACQUELINE A. , UPCROFT PETER
Published: May 2007

ABSTRACT. Twenty‐five in vitro cultures of Giardia duodenalis derived from a Brisbane patient were established to assess the genetic heterogeneity of a population. Each of the established lines carried a predominance of one of two distinct varieties of Giardia. The two varieties were heterogeneous by four unambiguous criteria that were representative of the whole genome. These included restriction enzyme polymorphisms, hybridization with the cloned rDNA repeat and with a gene encoding a cysteine‐rich surface protein, electrophoretic karyotyping and DNA fingerprinting. Differences between parasites derived from this patient were greater than have been seen between all other established G. duodenalis in vitro cultures from both human and animals. The culture were heavily selected such that a single Giardia line carried a predominance of one genotype and was not representative of the entire original population.
Survival of Tetrahymena thermophila at Low Initial Cell Densities. Effects of Lipids and Long‐Chain Alcohols
Authors: SCHOUSBOE PETER , RASMUSSEN LEIF
Published: May 2007

ABSTRACT. Cells of the ciliate Tetrahymena thermophila failed to establish cultures in lipid‐free standard synthetic nutrient medium if the initial population density was 250 cells per ml or less. These cells died within 10 h, but were saved and formed dense cultures if their medium was supplemented with 10 μg per ml of either certain phospholipids, 1,2‐di‐, 1‐monoglycerides, fatty acids, long‐chain alcohols, or sterols. Cell multiplication was followed in cultures in which the standard synthetic medium was supplemented with a selection of the compounds listed above. It was observed that the cells in the supplemented cultures in their exponential phases of growth had about the same average doubling times as control cells starting multiplication at 10‐fold higher initial cell densities in lipid‐free medium. These cells have been grown for decades in lipid‐free synthetic nutrient media at short (ca. two‐three h) doubling times. Therefore lipids have been considered nutritionally non‐essential for growth and multiplication of these cells. We propose that those compounds that rescue the cells at low cell densities act as “proliferation signals,”sensu lato. This effect of lipids and long‐chain alcohols has so far remained unnoticed.
A Rhodopsin‐like Molecule on the Plasma Membrane of Fabrea salina
Authors: PODESTA ADRIANO , MARANGONI ROBERTO , VILLANI CHIARA , COLOMBETTI GIULIANO
Published: May 2007

Immunofluorescence was used to reveal the presence of a rhodopsin‐like molecule on the plasma membrane of the photoresponsive ciliate Fabrea salina. The ciliate, fixed on a glass support, showed a spontaneous red‐orange fluorescence. Cells incubated with a fluoresceinated, anti‐bovine opsin, sheep polyclonal antiserum showed instead a green fluorescence typical of fluorochrome excited at 436 nm, whereas cells incubated with a fluoresceinated, nonimmune sheep serum kept their original red fluorescence. Excess bovine opsin did not inhibit the antibody reaction, but detergent‐coated purified bovine opsin was proven able to bind to the cell membrane. Since rhodopsin belongs to a gene‐related protein family, which includes adrenergic or cholinergic receptors, the cell response to acute exposure to muscarinic and adrenergic agonist and antagonist drugs was investigated. Acetylcholine, atropine, hexamethonium, noradrenaline, or phenoxybenzamine in the culture medium (10‐4 M) did not influence motion behaviour nor phototaxis of Fabrea salina. These findings raise the possibility that a rhodopsin‐like molecule is present on the surface of Fabrea salina. Nevertheless, they do not prove that this surface antigen is a rhodopsin, or that this molecule is responsible for photoresponsiveness in this organism.
Distribution of α‐Galactosyl‐Containing Epitopes on Trypanosoma cruzi Trypomastigote and Amastigote Forms from Infected Vero Cells Detected by Chagasic Antibodies
Authors: SOUTO‐PADRON THAIS , ALMEIDA IGOR C. , de SOUZA WANDERLEY , TRAVASSOS LUIZ R.
Published: May 2007

Reactivity of different Trypanosoma cruzi developmental forms with purified Chagasic anti‐α‐galactosyl antibodies (anti‐Gal) was studied using epimastigotes from axenic cultures, trypomastigotes and amastigotes from infected Vero cell cultures, and an immunogold labeling method as observed by electron microscopy. Epimastigotes were poorly labeled, whereas extracellular trypomastigotes and amastigotes bound heterogeneously to the antibody with many cells being intensely labeled at the cell surface, including the membrane lining the cell body, the flagellum and the flagellar pocket. Parasites with poor labeling at the cell surface generally had several gold particles within the cell, mostly in cytoplasmic vacuoles. The Golgi complex of trypomastigotes was strongly labeled. Intracellular parasites were labeled at the parasite cell surface or within vacuolar structures. The expression in T. cruzi‐infected Vero cells of α‐galactosyl antigenic structures acquired from the parasite was shown by moderate labeling with Chagasic anti‐Gal of the membrane lining parasite‐free outward cell projections. The reactivity with purified anti‐Gal from healthy individuals at the same concentrations of Chagasic anti‐Gal was poor, with gold particles appearing in the nucleus and cytoplasm but not at the cell surface. It paralleled the labeling with Bandeireae simplicifolia IB‐4 lectin. The results provide a basis for autoimmune reactions involving anti‐Gal from chronic Chagasic patients.
Early Expression of a Trypanosoma brucei VSG Gene Duplicated from an Incomplete Basic Copy
Authors: ALINE ROBERT F. , MYLER PETER J. , GOBRIGHT ELKE , STUART KENNETH D.
Published: May 2007

Intrachromosomal variant surface glycoprotein (VSG) genes in Trypanosoma brucei are expressed by a mechanism involving gene conversion. The 3’boundary of gene conversion is usually within the last 130 bp of the VSG gene, a region of partially conserved sequences. We report here the loss of the predominant telomeric A VSG gene in the cloned variant antigenic type (VAT) 5A3, leaving only an intrachromosomal A VSG gene (the A‐B gene). The nucleotide sequence of the A‐B VSG gene reveals that it lacks the normal VSG 3′ sequence. Surprisingly, we find cells expressing this A‐B VSG gene in relapse populations arising from VAT 5A3. Since the A VSG mRNAs from these cells have a normal 3′ sequence, the incomplete A‐B VSG gene must be expressed via a partial gene conversion that supplies the functional 3’end. Although the A‐B VSG gene is no longer predominant like the telomeric A VSG gene, it is still expressed more frequently than other intrachromosomal VSG genes, suggesting that factors other than a telomeric location determine whether a VSG gene is expressed early in a serodeme.
A Morphometric Analysis of the Euplotes charon Morphotype (Ciliophora: Euplotida)
Authors: JONES THOMAS C. , GATES MICHAEL A.
Published: May 2007

ABSTRACT Twenty‐one different strains of Euplotes of the cirrotype 10, double dargyrome morphotype were collected in marine and brackish habitats from widely varying geographic locations. The strains were cultured under similar conditions prior to fixation and staining. The morphological features considered included the cell lengths and widths, the number and position of all the ventral cirri, adoral membranelles and dorsal cilia, and the position of the peristomal shelf. Univariate and multivariate analyses revealed continua in these measurements among the strains, as well as significant correlations between cell length and the number of adoral membranelles, the number of dorsal cilia, and the length, width and area of the oral cavity. Based on data from this study and from previous studies, we conclude that the traditional criteria used for species descriptions within this morphotype are insufficient to provide robust distinctions. Therefore, we submerge all of the descriptions within this morphotype under the nomenclaturally superior Euplotes charon Müller, 1786.
Napamichum cellatum N. Sp. (Microspora, Thelohaniidae), a New Parasite of Midge Larvae of the Genus Endochironomus (Diptera, Chironomidae) in Sweden
Authors: BYLÉN EVA K. C. , LARSSON J. I. RONNY
Published: May 2007

ABSTRACT The new microsporidium, Napamichum cellatum, a parasite of the adipose tissue of midge larva of the genus Endochironomus in Sweden, is described based on light microscopic and ultrastructural characteristics. Plurinucleate Plasmodia with nuclei arranged as diplokarya divide, probably by plasmotomy, producing a small number of diplokaryotic merozoites. The number of merogonial cycles is unknown. Each diplokaryotic sporont yields eight monokaryotic sporoblasts in a thin‐walled, more or less fusiform sporophorous vesicle. A small number of multisporoblastic sporophorous vesicles were observed, in which a part of the sporoblasts were anomalous. The sporogony probably begins with a meiotic division. The mature spores are slightly pyriform. Fixed and stained spores measure 2.1‐2.4 × 3.7‐4.5 μm. The five‐layered spore wall is of the Napamichum type. The polar filament is anisofilar with seven to eight coils (142‐156 and 120 nm wide). The angle of tilt is 55‐65°. The polaroplast has an anterior lamellar and a posterior tubular part. The granular, tubular and crystal‐like inclusions of the episporontal space disappear more or less completely when the spores mature. The crystal‐like inclusions are prominent in haematoxylin staining, but not visible with the Giemsa technique. The microsporidium is compared to other octosporoblastic microsporidia of midge larva and to the species of the genera Chapmanium and Napamichum.
Attenuation of Parasite cAMP Levels in T. cruzi‐Host Cell Membrane Interactions In Vitro
Authors: VON KREUTER BETSY F. , WALTON BETH L. , SANTOS‐BUCH CHARLES A.
Published: May 2007

Previous investigations have shown that the adhesion of T. cruzi plasma membrane vesicles (PMV) to monolayers of host cell myoblasts and to immobilized heart muscle sarcolemma membranes (PAM) on polyaerylamide beads is mediated by the interaction of T. cruzi attachment sites with the muscarinic cholinergic and β‐adrenergic receptors of the host cell membrane. It has also been shown that this interaction is blunted by the specific antagonists of the mammalian receptors atropine and propranol, respectively. In the studies reported here, PAM also rapidly attached to swimming T. cruzi trypomastigotes in a complex, concentration‐dependent fashion and binding isotherms showed that the equilibrium between free and bound PAM is rapidly reached within 2 minutes of incubation in physiologically balanced salt solutions. In this time frame, trypomastigote cAMP levels are significantly reduced from steady state values within 30 seconds of the addition of PAM in a buffer system containing a diesterase inhibitor. Maximal attenuation of cAMP levels was measured between 1 and 2 minutes of the addition of PAM to T. cruzi trypomastigotes. The degree of cAMP level attenuation was reduced by blocking PAM attachment with either atropine or propranol. On the basis of these results we propose that a likely pathway for the negative parasite signal generated upon adhesion of host muscle cell membranes to the surface of the flagellates is from the parasite's surface attachment sites directly to a Pertussis toxin sensitive inhibitory protein Gi, thereby blunting adenyl cyclase activity and cAMP formation.
Circular rDNA Replicons Persist in Tetrahymena thermophila Transformants Synthesizing GGGGTC Telomeric Repeats
Authors: ROMERO DANIEL P. , BLACKBURN ELIZABETH H.
Published: May 2007

Site‐directed mutagenesis of the telomerase RNA from Tetrahymena thermophila was used previously to demonstrate the templating function of a sequence within this RNA; this sequence specifies the sequence of telomeric DNA in vivo. The possible functional importance of a phylogenetically conserved nucleotide outside the telomerase RNA template region was investigated by a similar experimental approach. The telomerase RNA gene was altered by site‐directed mutagenesis, cloned in a circular selectable transformation vector consisting of an rRNA gene carrying a selectable drug resistance marker, and introduced into macronuclei of vegetatively dividing Tetrahymena thermophila by microinjection. Changing an invariant A to U at position 16 of the telomerase RNA (A16U) had no effect detectable by phenotype on telomerase function in vivo. However these experiments showed that a telomerase template alteration that dictates the synthesis of the mutant telomeric DNA sequence GGGGTC leads to a profound change in the population of rDNA replicons. The addition of GGGGTC mutant repeats leads to selective pressure for the loss of high copy linear rDNA, and the rRNA genes are maintained in the form of the circular rDNA replicons introduced during transformation.
Histochemical Detection of Carbohydrates of Blastocystis hominis
Authors: YOSHIKAWA HISAO , KUWAYAMA NOBUKO , ENOSE YOSHIMI
Published: May 2007

The carbohydrates of Blastocystis hominis were detected by histochemical techniques using light and electron microscopy. B. hominis, fixed with various fixatives, followed by treatment with detergents, were stained with periodic acid‐Schiff (PAS) or alcian blue (AB). Intense PAS reactions were observed in cells fixed with glutaraldehyde or 1/2 Karnovsky fixative. The cells fixed with other fixatives showed weak or no reactions with PAS staining. Similar results were seen in the case of AB stain. These results indicated that, depending on the fixative used, B. hominis contained PAS‐ or AB‐reactive carbohydrates. At the electron microscopic level, ultrathin sections of B. hominis were stained with periodic acid methenamine silver (PA‐MS) or periodic acid thiocarbohydrazide‐silver proteinate (PA‐TCH‐SP) staining techniques. Intense, positive reactions with PA‐MS or PA‐TCH‐SP were observed on the central vacuole, Golgi apparatus, and cytoplasmic vesicles. The filamentous layer showed moderate reactions with PA‐MS, whereas in PA‐TCH‐SP stain, it was stained more densely. The staining intensity of the central vacuole varied from cell to cell. The presence of membrane fusions of the cytoplasmic vesicles with the central vacuole indicated the accumulation of carbohydrates in the central vacuole.
Chromosomal Evidence on the Sporogony of Amblyospora californica (Microspora: Amblyosporidae) in Culex tarsalis (Diptera: Culicidae)
Authors: CHEN WEI‐JUNE , BARR A. RALPH
Published: May 2007

ABSTRACT. Amblyospora californica is a polymorphic, eukaryotic microsporidian. Three types of sporogony producing three types of spores occur in male larvae and female adults of its mosquito host, Culex tarsalis, and an alternate copepod host, Acanthocyclops vernalis. Development of A. californica in male larvae includes merogony and sporogony. Karyogamy and meiosis was observed in sporogony in male larvae but not in the female adult or in the copepod. Chromosomal evidence showed that sporogony included two consecutive meiotic divisions and a subsequent mitosis forming an octosporont, ultimately containing eight haploid, uninucleate mature spores. In this species, the haploid number of chromosomes is nine. Macrosporoblasts and macrospores, containing 1, 2 or more nuclei, can be seen in infected male larvae. The stage of sporogony in which cytokinesis was arrested seems to determine the number of nuclei. Those with only one nucleus, we believe are due to failed nuclear division at meiosis. Although A. californica displayed a process of karyogamy and meiosis similar to that of the species from Cx. salinarius, they may not be the same species because of the difference in their chromosome numbers.