bluuebunny/crossref_metadata_2025 huggingface dataset:
Invasion of Babesia microti into Epithelial Cells of the Tick Gut1
Authors: RUDZINSKA MARIA A. , LEWENGRUB SONDRA , SPIELMAN ANDREW , PIESMAN JOSEPH
Published: May 2007

During feeding a peritrophic membrane (PM) is formed in the gut of the tick Ixodes dammini, dividing the lumen of the gut into an ecto‐ and endoperitrophic space. Babesia and all food particles ingested with the blood meal by the tick are retained in the endoperitrophic space, the lumen proper. Only Babesia equipped with a highly specialized organelle, the arrowhead, are able to pass the PM and enter the ectoperitrophic compartment. During the crossing of the PM the arrowhead loses its density, suggesting that enzymes released from it dissolve the polymers in the PM, making passage of the parasite through this barrier possible. In the ectoperitrophic space the arrowhead of Babesia touches the epithelial cell. At the point of contact the membrane of the host cell starts to invaginate, and simultaneously the arrowhead's fine structure loses its highly organized pattern. The growing host membrane encircles the parasite and the arrowhead diminishes progressively in size. When the piroplasm is inside the host cell, the arrowhead can no longer be found. During invasion the host membrane often touches the parasite's plasma membrane at the site of a coiled structure, and the host membrane becomes ruptured and the nearby host cytoplasm appears to be lysed. Babesia inside the host cell is covered solely by its own plasma membrane; the invaginated host membrane is missing. It is postulated that the latter disintegrates during invasion by the parasite through the action of enzymes from the coiled structure. The parasite is surrounded by a halo of homogeneous material deriving most probably from the lysed host cytoplasm.
Separation and Concentration of Schizonts of Plasmodium falciparum by Percoll Gradients1
Authors: RIVADENEIRA ENID M. , WASSERMAN MOISES , ESPINAL CARLOS T.
Published: May 2007

A technique for the separation of schizonts of Plasmodium falciparum is described. The different stages of the asexual cell cycle of the parasite were positioned according to their density in a continuous gradient of Percoll. Young trophozoites coincided with erythrocytes in a broad band corresponding to densities from 1.075 to 1.100 g/ml, whereas schizonts were concentrated at a density approximating 1.062 g/ml. The viability of the parasites was unimpaired by this procedure. Young trophozoites and schizonts continued their normal life cycle when cultured after the separation procedure. The percentage of recovery was high, reaching 80% of the initial quantity. Possible applications of the technique are discussed.
Isolation of Axopodial Axonemes from Mass‐cultured Echinosphaerium nucleofilum1
Authors: HOFFMAN EUGENE J. , PRICE DOUGLAS A. , KRUMPELMAN JAMES A.
Published: May 2007

The heliozoan Echinosphaerium nucleofilum produced about 75 times 103 floating cells per 19‐cm culture dish per day when fed the green flagellate Chlorogonium elongatum. This method yields enough cells for usable quantities of subcellular fractions. Heliozoa were lysed in a detergent mixture containing stabilizing reagents, and axonemal bundles of axopodial microtubules were isolated from the lysate by differential centrifugation. Polyacrylamide gel electrophoresis in sodium dodecylsulfate showed two prominent bands tentatively designated alpha‐ and beta‐tubulin. Apparent molecular weights were 51.8 times 103 and 48.1 times 103, respectively. As assayed by electron microscopy of negatively stained whole mounts, the microtubule bundles splintered readily, although glycerol tended to inhibit this fraying. Intermicrotubule bridges could be observed in some axonemal splinters.
The Neutral Lipids of Paramecium tetraurelia: Changes with Culture Age and the Detection of Steryl Esters in Ciliary Membranes1
Authors: KANESHIRO EDNA S. , MEYER KANIAULONO B. , REESE MARY L.
Published: May 2007

Neutral lipids, particularly triglycerides, accounted for the major decrease in the total lipid content in Paramecium cells that occurs with culture age. Sterols, triglycerides, and steryl esters were the major classes of neutral lipids in cells and isolated cilia. Free as well as high concentrations of esterified sterols were detected in purified ciliary membrane preparations. Stigmasterol and 7‐dehydrostigmasterol were the major components of both free and esterified sterols of cells and cilia; however, when cholesterol was present in the growth medium, it was desaturated to 7‐dehydrocholesterol and incorporated into cellular and ciliary lipids. Free fatty acids from cells and triglycerides from cells and cilia were low in polyunsaturated fatty acids and reflected the composition of fatty acids in the culture medium. An exception was the reduced concentration of stearate in triglycerides from whole cells. Greater than 50% of triglyceride fatty acids from cilia were saturated. The fatty acid compositions of cellular triglycerides and ciliary steryl esters did not change with culture age, but those of cellular steryl esters and ciliary triglycerides did change. In comparison with phospholipids, these neutral lipid fatty acid compositional changes were smaller. The sensitivity of these stigmasterol‐containing cells to polyene antibiotics indicated that they were killed by nystatin > filipin > amphotericin B. The unexpected finding of high concentrations of steryl esters in ciliary membrane preparations is discussed.
The Pathogenic Amoeboflagellate Naegleria fowleri: Environmental Isolations, Competitors, Ecologic Interactions, and the Flagellate‐Empty Habitat Hypothesis1
Authors: GRIFFIN JOE L.
Published: May 2007

From several surveys of environmental sites, the virulent human pathogen, Naegleria fowleri, was isolated from a pond in Georgia, a sewage treatment plant in Missouri, and from the Potomac and Anacostia rivers near and in Washington, D.C. Widely scattered, sparse populations seemed only a potential threat to human health at the time of sampling. The data support an estimate that the sites sampled contain 10,000 typical, low temperature, bactivorous amoebae for each heat tolerant amoeba able to grow at 45° C. Heat tolerant competitors were much more common than N. fowleri. Naegleria lovaniensis, which is heat tolerant but nonpathogenic, was isolated from and downstream from an open air thermal pollution temperature gradient. Hot piles of composting sewage sludge yielded no amoeboflagellates, many heat tolerant (45–49° C) amoebae, and one thermophilic (52° C) Acanthamoeba. Features of the methods used include two‐stage incubation to increase isolation of sparse organisms and distinction of N. fowleri from almost all other amoebae on agar plates. The flagellate‐empty habitat hypothesis postulates a general model in which human intervention and/ or natural events remove usual competitors and the ability to transform to a motile flagellate confers an advantage in recolonizing.
True Intermediate Hosts for Eimeria funduli (Apicomplexa) from Estuarine Fishes1
Authors: FOURNIE JOHN W. , OVERSTREET ROBIN M.
Published: May 2007

Grass shrimp (Palaemonetes pugio) fed liver containing sporulated oocysts of Eimeria funduli permitted development of sporozoites that became infective to a variety of killifishes. The shrimp's gastric mill mechanically ruptured the oocysts. Sporozoites then excysted through an opening in the sporocyst, and by 12 and 13 h postinfection (p.i.) numerous empty sporocysts and free sporozoites occurred extracellularly in the intestine of the grass shrimp. Even at 5, 7, 8, 11, 46, 79, and 83 days p.i., and presumably for many months, numerous sporozoites still occurred free in the alimentary tract or between intestinal cells. The coccidium did not infect killifish at either 2 or 4 days p.i., but did at 5 days; after release from the sporocyst, it became more elongate with a distinct nucleus and two relatively large refractile bodies. Infections of E. funduli resulted in about one half of the fish that were fed either entire hepatopancreas or tips of hepatopancreas from experimentally infected shrimp. Feeding either the entire alimentary tract proximal to the first abdominal segment or any portion of that section from experimentally infected shrimp produced infections in nearly all tested fish. Feeding portions of the cephalothorax without any attached hepatopancreas or alimentary tract failed to produce an infection. Feeding killifish with wild grass shrimp from an enzootic area produced infections in only a fourth of the fish sample; however, feeding experimentally infected wild, laboratory‐reared, and juvenile grass shrimp produced infections in nearly all fish. Palaemonid shrimps other than P. pugio also can serve as intermediate hosts for E. funduli, and these shrimps include Palaemonetes vulgaris, P. paludosus, P. kadiakensis, and Macrobrachium ohione. In contrast, a penaeid shrimp, mysidacean, amphipod, and crab fed liver with sporulated oocysts did not produce infections when fed to killifish.
The Cytology of Sheep Rumen Ciliates. I. Ultrastructure of Epidinium caudatum Crawley1
Authors: FURNESS D. N. , BUTLER R. D.
Published: May 2007

Epidinium caudatum has an anterior vestibulum containing the adoral zone syncilia (AZS) on an extrusible peristome. The cytopharyngeal structures include a funnel‐shaped arrangement of nematodesmata, longitudinal and transversely oriented microtubular ribbons all of which are located in the peristome, a structure which also contains filamentous phagoplasm. The origins of the microtubular ribbons indicate affinities to the rhabdos type of cytopharynx. The peristomal base is continuous with the tubular esophagus, the region connecting the two being ensheathed by a fibrous layer and low density cytoplasm. The esophagus has a microtubular/microfilamentous wall. A distinct cytoproct with associated myonemal structures occurs posteriorly. The skeletal plates consist of a large number of interconnected, variably shaped platelets and may have dual skeletal and storage functions. The endoplasm is more vesicular than the ectoplasm, the two separated by a fibrous boundary layer. The five‐layered cortex has an external glycocalyx, a plasma membrane with two subtending membranes, homogeneous, microtubular, and microfilamentous layers. The syncilia of the AZS are mounted in a U‐shaped band on the peristome with transversely oriented kinetics consisting of kinetosomes linked by a sub‐kinetosomal rod. There is a bifurcated kinetodesma, dense support material forming a lateral spur with associated transverse microtubules, and postciliary, interkinetal, and occasional basal microtubules, nematodesmata, and a subciliary reticulum. A barren, possibly vestigial, somatic infraciliature consists of non‐ciliated kinetosomes and a basal striated fiber with associated basal and perpendicular (cortical) microtubules.
Scanning Electron Microscopy of Attached Trophozoites of Pathogenic Entamoeba histolytica1
Authors: GONZALEZ‐ROBLES ARTURO , MARTINEZ‐PALOMO ADOLFO
Published: May 2007

The surface morphology of Entamoeba histolytica trophozoites of HM 1:IMSS (axenic and monoxenic) and HK9 (axenic) strains cultured on plastic and MDCK cell substrates was examined using scanning electron microscopy (SEM). The conditions for processing trophozoites were determined by comparing the SEM observations with the morphology of living amebas examined by light microscopy. The most frequent surface differentiations in all the amebas observed with SEM were lobopodia. Round cytoplasmic projections were found in approximately half of the axenic amebas. Endocytic stomas and filopodia were more common in monoxenic cultures while the uroid was found in only 2–8% of all examined amebas. The basal surfaces of the trophozoites, involved in both attachment and cytolysis, showed no unusual features, except for the presence of a small number of short filopodia at the outer edge. No differences were found in the morphology of amebas grown on artificial and natural substrates. These observations demonstrate that there are significant quantitative differences in the surface morphology of cultured trophozoites of different strains of E. histolytica and that association with bacteria produces an increase in the relative number of surface specializations of the parasite.
Strain‐Specific Proteins of Symbiont‐Containing Amoeba proteus Detected by Two‐Dimensional Gel Electrophoresis1
Authors: AHN T. I. , JEON K. W.
Published: May 2007

Two‐dimensional gel electrophoresis was used to compare the protein composition of normal (D strain) and symbiont‐containing (xD strain) A. proteus. Over 500 different peptide spots could be identified on a typical gel of cytosol proteins. In addition to differences in a few minor peptides, one prominent polypeptide with an isoelectric point of about 5.5 and a molecular weight of about 29,000 was present in the cytoplasm of symbiont‐containing amoebae and in the endosymbionts but not in D‐strain amoebae. When endosymbionts were removed from xD‐strain amoebae, the xD‐specific polypeptide also disappeared, suggesting that it is produced by the endosymbionts.
Fine Structure of Yellow‐Brown Symbionts (Prymnesiida) in Solitary Radiolaria and Their Comparison with Similar Acantharian Symbionts1
Authors: ANDERSON O. R. , SWANBERG N. R. , BENNETT P.
Published: May 2007

Yellow‐brown, algal symbionts varying in diameter from approximately 5 μ m to 20 μ m, associated with solitary Radiolaria with spongiose skeletons (i.e. Spongodrymus sp.), exhibit fine structural features resembling the Prymnesiida (botanical class, Prymnesiophyceae). A large central vacuole is surrounded by a thin layer of cytoplasm containing plastids with lamellae composed of three thylakoids and granular pyrenoids with internal tubules immersed between the thylakoids. The pyrenoids lack internal thylakoid membranes. The nucleus is surrounded by a dilated cisterna of the nuclear envelope that also encloses the plastids and gives rise to saccules of the endoplasmic reticulum. The algal symbionts appear coccoid; hence no flagella nor surface scales were observed. The symbiont fine structure is compared to similar yellow‐brown symbionts associated with Acantharia. Thus far, three kinds of algal symbionts have been observed to be associated with solitary Radiolaria: dinoflagellate, prasinomonad, and this apparent prymnesiomonad.
Altered Flagellar Size‐Control in shf‐1 Short‐Flagella Mutants of Chlamydomonas reinhardtii
Authors: JARVIK JONATHAN W. , REINHART FREDERICK D. , KUCHKA MICHAEL R. , ADLER SALLY A.
Published: May 2007

Two allelic Mendelian mutations which confer a short flagella phenotype were used to explore flagellar size control in Chlamydomonas reinhardtii. When mutant/wild type quadriflagellate dikaryon cells were constructed, their two short flagella rapidly grew out to near wild type length. The kinetics of elongation suggest that the flagellar assembly process is not intrinsically self‐limiting as a number of otherwise attractive models for size control require. Instead, we suggest that there exists a cellular machinery dedicated to flagellar size control and that the short‐flagella mutations alter the machinery in some as yet unknown way. One of the mutants shows temperature‐sensitive flagellar assembly, and both are flagellaless in acetate media. Genetic analysis indicates that the temperaturesensitive, acetate‐sensitive, and short‐flagella phenotypes have a common genetic basis. The responsible gene has been named shf‐1, and it has been mapped to chromosome VI, approximately 5 map units from the centromere.
Scale Formation in an Amoeba, Cochliopodium sp.
Authors: YAMAOKA IKUO , KAWAMURA NOBUYUKI , MIZUNO MANAKO , NAGATANI YOSHIMI
Published: May 2007

During excystment of an amoeba, Cochliopodium sp., scale formation was examined with light and electron microscopy. This amoeba was covered with scales. When the amoeba encysted, the scales remained on the external surface of the cyst wall. Soon after the induction of excystment the Golgi complex began to develop. Many vesicles were extruded from it and changed into vacuoles. Scales were observed first in the vacuole adjacent to the Golgi complex and later in inside the cyst wall. When the amoeba excysted it had been coated by the newly formed scales. It is suggested that the scale formation is dependent on the activity of the Golgi complex.
Characterization of a Mutant of Toxoplasma gondii Resistant to Aphidicolin1
Authors: PFEFFERKORN E. R.
Published: May 2007

Aphidicolin, a mycotoxin that inhibits eucaryotic DNA polymerase alpha, blocked the growth of Toxoplasma gondii in confluent cultured human fibroblasts. Aphidicolin immediately inhibited DNA synthesis by T. gondii while it had a delayed and less dramatic effect on RNA synthesis. A mutant of T. gondii resistant to aphidicolin was isolated with the aid of mutagenesis by ethylnitrosourea. Parasite growth measured three days after drug treatment and parasite DNA synthesis measured immediately after drug treatment were, respectively, five‐ and four‐fold more resistant to aphidicolin in the mutant as compared with the wild type parasite. The mutant had a three‐fold greater capacity than the wild type to incorporate uracil into its deoxycytidine triphosphate pool. This increased deoxycytidine triphosphate pool is the probable explanation for the mutant's resistance because this deoxynucleotide is known, in mammalian cells, to reverse the inhibition of DNA synthesis by aphidicolin in a competitive manner.
Eimeria beldingiin. sp. and Other Coccidia (Apicomplexa) of the Ground SquirrelSpermophilus beldingi1
Authors: VELUVOLU PUSHPAVATHY , LEVINE NORMAN D.
Published: May 2007

Fecal samples of 36 ground squirrels,Spermophilus beldingi, from Tioga Pass (elev. ca. 3315 m) in the Sierra Nevada, California, yielded oocysts ofEimeria beckeriin nine squirrels,E. citelliin four squirrels,E. beldingiin. sp. in two squirrels, and degenerated, unidentifiable oocysts in ten squirrels.Eimeria beldingiin. sp. oocysts are ellipsoidal, 30–34 × 24–30 (mean 32 × 26) μm with a two‐layered, rough, striated wall, without a micropyle or residuum, with polar granules; they contain ellipsoidal or ovoid sporocysts 11–15 × 9–12 (mean 13 × 10) μm with a Stieda body and residuum.
Chemical Induction of Autogamy in Paramecium multimicronucleatum, Syngen 21
Authors: SHIMOMURA FUMIYO , TAKAGI YOSHIOMI
Published: May 2007

The combination of KCl + acriflavine + Ca2+‐poor condition, known as conjugation‐inducing‐chemicals, was found to be autogamy‐inducing‐chemicals as well. Suspension of a single cell of Paramecium multimicronucleatum, syngen 2 in this medium for three hours or more resulted in autogamy that was evidenced by cytological similarity to conjugation.
Detection of Giardia in Sewage Effluent1
Authors: McHARRY MARGARET J.
Published: May 2007

Giardia sp. cysts were found at levels of 4,000–450,000/378,500 liters (100,000 gallons) in sewage effluents from three of seven sewage treatment plants in Sangamon County, Illinois, in June, July, and August 1981. Effluent from the positive plants is discharged into Lake Springfield (the present source of the city of Springfield's water supply) or the Sangamon River.
The Effects of Aspirin‐Containing Serum in the Continuous Culture of Plasmodium falciparum1
Authors: WHAUN JUNE M.
Published: May 2007

In vitro culture of Plasmodium falciparum‐infected human erythrocytes (RBC) has permitted systematic study of human host‐parasite relations. In this study the effect of aspirin in the culture system was examined by using serum from blood of fasting, healthy male volunteers, before and after the ingestion of aspirin. The addition of aspirin‐containing serum disturbed parasite growth and development: 0‐1/2 dilutions of treated/control sera inhibited parasite development, with nuclear pyknosis, pyknotic extracellular parasites (trophozoites) in the media, decreased numbers and sizes of “rings” (early trophozoites), and an increased number of later trophozoites and schizonts. Paradoxically, while the incorporation of [3H]isoleucine into protein was not affected by the aspirin‐containing sera, the incorporation [3H]hypoxanthine was significantly changed and did not correlate with morphological evidence of cytotoxicity. Thus, the so‐called “incorporation” of a radioactive tracer is not a fully reliable index of parasite growth in the presence of certain compounds. The findings underscore the importance, in this culture system which employs human serum, of avoiding serum from donors who have recently ingested aspirin.
Trypanosoma cruzi from the Paraguayan Chaco: Isoenzyme Profiles of Strains Isolated at Makthlawaiya1
Authors: CHAPMAN MARTIN D. , BAGGALEY RACHEL C. , GODFREY‐FAUSSET PETER F. , MALPAS TIMOTHY J. , WHITE GENEVIEVE , CANESE JORGE , MILES MICHAEL A.
Published: May 2007

At Makthlawaiya, in the Paraguayan Chaco, the prevalence of Trypanosoma (Schizotrypanum) cruzi infection among both domestic Triatoma infestans and domestic dogs was 38%, and IgG anti‐T. cruzi antibody was detected by the quantitative enzyme‐linked immunosorbent assay (ELISA) in 80% (105/133) of human sera. Ninety percent (25/28) of T. cruzi strains isolated from both T. infestans and dogs showed heterozygous isoenzyme profiles for glucose phosphate isomerase, phosphoglucomutase and 6‐phosphogluconate dehydrogenase. These strains appeared to be closely related to Bolivian zymodeme 2. Three Paraguayan T. cruzi strains showed homozygous isoenzyme profiles, similar to those of major Brazilian zymodemes. It was concluded that T. cruzi strains with heterozygous isoenzyme profiles predominate in domestic transmission cycles in this highly endemic area of the Paraguayan Chaco.
The Surface of the African Trypanosomes1,2
Authors: RICHARDS FRANK F.
Published: May 2007

The African trypanosomes bear on the outside of their cell membrane a single 10–15 nm thick coat of a glycoprotein. This glycoprotein may differ in structure in the predominant populations of parasitemic waves found in relapsing infections. Variant Specific Glycoprotein (VSG) range in MW between 53,000–63,000 d and may have variable amounts of carbohydrate attached at one, two, or several loci. Such differences in carbohydrate content may account in part for their range in molecular size. Approximately 30 C‐terminal residues demonstrate isotypy; i.e. these regions fall into classes having similar amino acid sequence. Modest homology has been demonstrated in two VSGs of T. congolense arising in relapsing infections although comparison of many VSG show little or no obvious homology. More recently, lipid‐associated forms of VSG have been described and it is believed that these forms may be transmembrane proteins. Different VSGs appear to have different amounts of the primary sequence which have alpha‐helix‐forming potential. In some VSG, in excess of 80% of the structure is helical as judged by both Chou‐Fasman calculations and by circular dichroism. This raises the possibility that different VSG may have different folding patterns. The arrangement of VSG on the trypanosome surface probably places the basic amino acid‐rich carbohydrate‐bearing C‐terminus of the polypeptide chain close to the membrane. There is some protein‐protein association between VSGs for which (in T. evansi) the C‐terminal tail is not required. The importance of VSG structure lies not only in the fact that the molecule mediates the phenomenon of antigenic variation but also in the recent observation that VSG may act on the cellular immune system to suppress the humoral immune responses of the host.
Trichodinid Protozoa (Ciliophora: Peritrichida) from Freshwater Fishes of Rybinsk Reservoir, USSR1
Authors: ARTHUR J. R. , LOM J.
Published: May 2007

During the spring of 1981, trichodinid protozoa were collected from the gills or urinary bladder of the following species of fishes of Rybinsk Reservoir, USSR, located on the upper reaches of the Volga River system: Esox lucius, Rutilus rutilus, Leuciscus idus, Blicca bjoerkna, Abramis ballerus, Pelecus cultratus, Lota lota, and Perca fluviatilis. A total of 13 species of Trichodinidae was recovered from Rybinsk fishes, among which are three new species of the genus Trichodina: T. izyumovae n. sp. from the gills of L. idus, T. borokensis n. sp. from the gills of P. cultratus, and T. kupermani n. sp. from the gills of A. ballerus. Other species of trichodinids reported are T. modesta Lom, 1980; T. nigra Lom, 1969; T. pediculus (O. F. Müller, 1786); T. prowazeki Grupcheva & Lom, 1980; T. rostrata Kulemina, 1968; T. urinaria Dogiel, 1940; T. ophiocephalus Kostenko & Karaev, 1976; Paratrichodina incisa (Lom, 1959); Trichodinella epizootica (Raabe, 1950); and Tripartiella copiosa Lom, 1959. Photomicrographs and morphometric data are presented for each species and aspects of their host and geographic distribution discussed. Trichodina algonquinensis Li & Desser, 1983 is considered a synonym of T. urinaria Dogiel, 1940.
Taxonomy and Review of the Coccidian GenusCryptosporidium(Protozoa, Apicomplexa)1
Authors: LEVINE NORMAN D.
Published: May 2007

Reports ofCryptosporidiumin various hosts and cross‐transmission experiments are reviewed.Cryptosporidiumhas been found in mammals (Primates, Artiodactyla, Perissodactyla, Carnivora, Lagomorpha, and Rodentia), birds, reptiles, and fish. The only cross‐transmission attempts that have been made have been from mammals to other mammals and to a few birds. Names have been given to 19 “species,” but it is concluded that only four of these should be considered valid at present. These are:C. murisTyzzer, 1907 in mammals,C. meleagridisSlavin, 1955 in birds,C. crotaliTriffit, 1925 in reptiles, andC. nasorumHoover, Hoerr, Carlton, Hinsman & Ferguson, 1981 in fish.
The Morphology of Ovine Trypanosoma melophagium (Zoomastigophorea: Kinetoplastida)1
Authors: BÜSCHER G. , FRIEDHOFF K. T.
Published: May 2007

Morphologic and biometric data on bloodstream stages of Trypanosoma melophagium are presented. An increasing parasitemia with 111 trypomastigote stages of T. melophagium were found in Giemsa‐stained thin blood smears taken from a splenectomized, cortisone‐treated sheep recently infested with Melophagus ovinus infected with T. melophagium. The arithmetic mean and standard deviation in μm of the distances between posterior end and kinetoplast were 14.7 and 2.9, from the kinetoplast to the center of the nucleus 5.1 and 1.1, and from there to the anterior end 19.5 and 1.9. The free flagellum measured 6.0 μm ± 1.6 μm. The median and the range of the central 70% of values (median ± 35%) of the nuclear index were 1.1 and 0.9–1.2 and of the kinetoplastic index 3.8 and 3.3–4.9. The same data in μm for the maximal width were 3.1 and 2.1–4.6, and for the width at the level of the nucleus 2.9 and 2.2–4.6. The larger and smaller diameters of the nucleus measured 2.6 (2.2–3.7) μm and 1.7 (1.3–1.7) μm, respectively. The corresponding kinetoplast diameters were 1.1 (0.9–1.3) μm and 0.9 (0.6–0.9) μm, respectively.
Activation of Glycogen Phosphorylase by Cyclic AMP in Tetrahymena pyriformis1
Authors: MUTO YOSHINORI , KUDO SHUZO , NOZAWA YOSHINORI
Published: May 2007

Glycogen phosphorylase in Tetrahymena pyriformis was activated by a Mg2+ ATP‐dependent process and this activation was further increased by the addition of cyclic AMP. When the enzyme activity in subcellular fractions was measured, it was largely associated with the glycogen fraction but was no longer activated by ATP and cyclic AMP. Mixing the glycogen fraction and cytosol fraction together restored the effects of ATP and cyclic AMP on phosphorylase activity. These findings suggest that glycogen phosphorylase associated with Tetrahymena glycogen granules may be regulated by cytosolic factor(s) with cyclic AMP.
Development of Second Generation Merozoites of Leucocytozoon caulleryi In Vitro
Authors: ISOBE T. , YAMAGUCHI S. , IMADA T. , KAWAKITA F. , AKIBA K.
Published: May 2007

Sporozoites of Leucocytozoon caulleryi were inoculated into specific‐pathogen‐free (SPF) chickens intravenously. Fourteen days after inoculation, the infected blood, parasitized with second generation merozoites, was collected from the chickens. The blood was then suspended in SPF chicken serum or RPMI‐1640 culture medium supplemented with 20% SPF chicken serum in petri dishes, which were cultured at 37°C or 41°C in a humidified atmosphere of 5% CO2. Second generation merozoites in parasitized, immature erythrocytes developed continuously through several substages and finally became micro‐ and macro‐gametocytes after 6 days of incubation.
Norlevinea n. g., a New Genus for Glugea daphniae (Protozoa: Microspore), a Parasite of Daphnia longispina (Crustacea: Phyllopoda)1
Authors: VÁVRA JIR̀Í
Published: May 2007

ABSTRACT. Norlevinea n. g. is established for microsporidia in which a uninucleate meront changes into a sporont by secreting a thin, membranous, sporontogcnetic and fragile sporophorous vesicle (pansporoblast membrane) in which four uninucleate sporoblasts are formed. In contrast to the genus Gurleya, the sporoblasts and later the spores are permanently joined into doublets, being laterally cemented by an electron‐dense substance structurally identical to and continuous with the exospore layer. The polar filament is of the anisofilar type. The type species is Norlevinea daphniae (Weiser, 1947) n. comb., a parasite of the ovaries of Daphnia longispina occurring in several carp ponds in Czechoslovakia.
Karyolysus sp. (Haemogregarinidae, Adeleida, Apicomplexa): Host‐Parasite Relationships of Persisting Stages
Authors: BEYER TAMARA V. , SIDORENKO NINA V.
Published: May 2007

ABSTRACT. Two persisting stages in the life cycle of a hemogregarine Karyolysus sp. are described from the liver and blood cells of its intermediate host, the lizard Lacerta raddei nairensis. The tissue cell merozoites lie in a parasitophorous vacuole. Despite the protective role of the vacuolar membrane, the intracellular parasites are progressively destroyed and eliminated during the autumn and winter. Some of the merozoites that normally survive within the host cell even in cold seasons appear to be surrounded by another type of parasitophorous vacuole which is connected to the intercellular space by narrow channels. The intraerythrocytic gamonts that persist in the circulating blood are encapsulated and undergo progressive, obvious structural changes. The two persisting stages are compared with hypnozoites of other Sporozoa.
The Catabolism of Tryptophan to Indole‐3‐Ethanol by Crithidia fasciculata and Phytomonas davidi1
Authors: Seed John R. , Hall James Edwin , Sechelski John
Published: May 2007

Crithidia fasciculata and Phytomonas davidi catabolize tryptophan (TRP) to indole‐3‐ethanol, which was identified by both thin layer and gas chromatography. The catabolic pathway involved in this metabolic conversion is suggested to be similar to that proposed for other members of the family Trypanosomatidae. Although this catabolism occurs at both 25° and 37°C, the catabolic rate is greater at 37°C, a non‐permissive growth temperature. Conditions that inhibit protein synthesis would appear to favor the catabolism of tryptophan to indole‐3‐ethanol. The possible importance of this catabolic pathway to these organisms is discussed.
Observation on Complete Schizogony of Plasmodium vivax in Vitro1
Authors: Brockelman Chariya R. , Tan‐Ariya Peerapan , Laovanitch Ratchapin
Published: May 2007

Attempts to grow Plasmodium vivax in vitro were made on 43 isolates in three different culture media. Complete schizogony occurred in the new medium SCMI 612 in which 34 out of 43 isolates produced merozoites. The RPMI 1640 and Waymouth media suitable for the cultivation of P. falciparum were also used with markedly less success. Results of the experiments indicate differences in nutritional requirements between the two species of Plasmodium.
Trypanosoma cruzi: Biological Characterization of Clones Derived from Chronic Chagasic Patients. II. Quantitative Analysis of the Intracellular Cycle1
Authors: Engel Juan C. , Doyle Patricia S. , Dvorak James A.
Published: May 2007

The complete intracellular cycle of five cloned stocks of Trypanosoma cruzi was quantified. Marked but stable interclonal differences were found in the length of the pre‐replicative lag period (18.2‐34.2 h), amastigote doubling lime (8.6‐21.5 h), and duration of the complete intracellular cycle (96‐215 h). Strong correlations were demonstrated between these characteristics as well as to the growth rate of the epimastigote stage of the same clones grown in liquid medium. These data demonstrate that the marked heterogeneity of the natural population of T. cruzi extends to the intracellular cycle of the parasite and has important implications for our understanding of Chagas’ disease.
Long‐Term Patterns of Protozoan Colonization in Douglas Lake, Michigan
Authors: Pratt James R. , Cairns John
Published: May 2007

Long‐term patterns of noninteractive and interactive protozoan colonization of polyurethane foam (PF) artificial substrates in Douglas Lake, Michigan, were examined for a 14‐yr period. Species‐time data were fitted to the Mac Arthur‐Wilson equilibrium model, S =Šeq(1 ‐ eGt), and examined through time from 1969‐1982. Comparisons were made to historical water chemistry measurements. No long‐term changes in water chemistry were evident. Similarly, equilibrium species number (Šeq) and colonization rate (G) oscillated about a mean through time. Protozoan colonization of PF substrates appeared stable for extended periods and showed modest variation from year to year. Examination of 7‐yr‐old substrates in 1982 revealed little difference from young (< 50 days) substrates. Previous reports of senescence of artificial substrate communities may have been due to habitat loss within the substrates. No evidence existed for chemical or biological degradation of the lake.
Electron Microscope Autoradiography of DNA Synthesis in the Replication Band of Two Hypotrichous Ciliates1
Authors: Lin Meiying , Prescott David M.
Published: May 2007

The synthesis of DNA in two hypotrichous ciliates, Styx sp. and an amicronucleated strain of Oxytricha sp., was studied by high voltage (1000 kV) electron microscopy. High voltage EM permits use of thick sections (0.25‐0.40 μm), including serial sections; thick sections produce strong autoradiographic images with relatively short exposure times. The autoradiographs show that DNA synthesis occurs in a narrow part of the rear zone of a replication band in the macronucleus. Macronuclear DNA synthesis occupies a substantial part of the interdivision interval, and micronuclear DNA synthesis in Styx sp. takes place in early prophase at a time when macronuclear DNA synthesis is in its terminal phase.
Macrophage Activation by Tetrahymena pyriformis. I. Active Subcellular Fractions of Tetrahymena
Authors: Makioka Asao , Kobayashi Akio
Published: May 2007

Experiments were carried out to determine what subcellular fractions of Tetrahymena pyriformis could, after inoculation into mice, activate macrophages to kill Toxoplasma gondii in vitro. Peritoneal macrophages from mice inoculated intraperitoneally with cilia, pellicles, mitochondria, and microsomes exhibited strong toxoplasmacidal activity and had an enhanced capacity to release hydrogen peroxide (H2O2) by stimulation of a membrane‐active agent as compared with resident macrophages. In contrast, macrophages from mice inoculated with macronuclei and postmicrosomal supernatant showed no toxoplasmacidal activity and a low level of H2O2 release. Similar dose response was observed on the active subcellular fractions with regard to the degree of macrophage activation. Treatment of the active subcellular fractions with heating and trypsin markedly reduced their activity.
Biochemical Identification and Phylogenetic Relationships in Free‐Living Amoebas of the Genus Naegleria1
Authors: PERNIN PIERRE , CARIOU MARIE‐LOUISE , JACQUIER ARLETTE
Published: May 2007

Using isoelectric focusing, the zymograms of 23 pathogenic and nonpathogenic Naegleria strains were studied for the activity of 16 enzymes. Certain enzymes (lactate dehydrogenase, L‐threonine dehydrogenase, superoxide dismutase, acid phosphatase, malic enzyme, and leucine aminopeptidase) proved particularly useful from a practical point of view as they allow easy and reliable identification of pathogenic N. fowleri and N. australiensis as well as nonpathogenic N. lovaniensis strains. Genetic interpretation of these zymograms gave estimates of genetic distances that largely confirmed the taxonomic position of the Naegleria species. In addition, the genetic data suggest that there are two main phylogenetic groups in the genus Naegleria.
Pleiotropic Effects of a Temperature‐Sensitive Mouthless Mutation in Tetrahymena thermophila on the Excretion of Extracellular Enzymes
Authors: NIELSEN TORBEN , VILLADSEN INGRID S.
Published: May 2007

The mode of enzyme excretion was investigated during balanced growth in wild type Tetrahymena thermophila and in a temperature‐sensitive mutant that did not form a mouth and food vacuoles at the restrictive temperature. The mutant was used to determine which of the extracellular enzymes are normally excreted by defecation. During balanced growth at the permissive temperature the excretion of enzymes was constant, and maximal in complex medium. No protease activity against azocasein was detected. Changes in the growth temperature of the wild type cells only affected the release of 3′‐nucleotidase. For the mutant, however, the excretion changed markedly with increasing temperature: (a) ribonuclease, deoxyribonuclease, α‐glucosidase, and β‐glucosidase were detected in 0–10% of normal amounts; (b) 3′‐ and 5′‐nucleotidase, not measured previously in Tetrahymena, were found in 10‐ to 14‐fold of normal amounts; (c) excretion of acid phosphatase was unaffected. We therefore conclude that the extracellular enzymes (a) are released by defecation, that 3′‐ and 5′‐nucleotidase are secreted through the membrane system, and that acid phosphatase is released by lysosomes emptied through pinocytosis. It is proposed that the lysosomes used for the formation of digestive vacuoles are different from those used for the formation of pinocytotic vacuoles and for autophagic vacuoles.
Interactions of Giardia lamblia with Human Intestinal Mucus: Enhancement of Trophozoite Attachment to Glass1
Authors: ZENIAN ASADOUR , GILLIN FRANCES D.
Published: May 2007

Giardia lamblia trophozoites frequently are associated with mucus in vivo. We investigated the effects of human intestinal mucus on parasite attachment and survival in vitro. All samples of mucus from the duodenum and ileum (from four humans and two rabbits) enhanced attachment at 100 μm/ml. Attachment increased with mucus concentrations from 1 to 1000 μg/ml but declined toward the unstimulated level at concentrations above 1000 μg/ml. Mucus from the small intestine also promoted the survival of the parasites during the 2‐h incubation. In contrast, colonic mucus promoted survival, but inhibited attachment. Fractionation of mucus from the human small intestine by cesium chloride equilibrium density gradient ultracentrifugation revealed that both attachment‐ and survival‐promoting activities were in the low density, protein‐rich fraction. The high density fractions containing the mucins were devoid of activity. Thus, a non‐mucin fraction of mucus from the human small intestine may promote colonization by G. lamblia.
Development of the Swine Coccidium Eimeria debliecki Douwes, 1921 in Mammalian Cell Cultures1
Authors: LINDSAY DAVID S. , BLAGBURN BYRON L. , CURRENT WILLIAM L. , ERNST JOHN V.
Published: May 2007

Sporozoites of Eimeria debliecki entered human fetal lung and porcine kidney cells grown in cultures and underwent one merogenous cycle, terminating in the production of second‐generation trophozoites. Sporozoites were intracellular 1 h post‐inoculation (PI) and developed into sporozoite‐shaped meronts at 40 h PI. These meronts, one of which was motile, had from two to ten nuclei. Sporozoite‐shaped meronts then developed into elongate or spheroidal meronts with 10 to 24 nuclei by two days PI. Ten to 26 first‐generation merozoites were formed by budding from the meront surface. Mature first‐generation merozoites were most numerous three days PI. Most meronts had ruptured and released nonmotile merozoites into the culture medium by four days PI. Merozoites that were not released became rounded and developed into second‐generation trophozoites. Refractile bodies were present in all developmental stages. No further development was observed five through eight days PI.
An Ultrastructural and Cytochemical Study of the Cell Surface of a Suctorian Ciliate1
Authors: SUNDERMANN CHRISTINE A. , PAULIN JEROME J.
Published: May 2007

The surfaces of the main cell body, tentacle shaft, and knob of Discophrya collini, a freshwater suctorian ciliate, were characterized using various cytochemical techniques. Cells prepared for conventional transmission electron microscopy exhibited a 50–60 nm thick fuzzy layer over the cell body surface; this layer was absent from the tentacle knob. A thick (240 nm), two‐layered surface coat surrounding the main cell body was stained with ruthenium red. This heavy coat was absent from the surface of the knob where a thin, dense, ruthenium red‐positive layer and projecting filaments were present. Freeze‐etched material revealed a “particle region” (150–250 nm in thickness) closely associated with the outer cell surface of the suctorian. Fixed specimens were treated with four different lectins and analyzed with electron microscopy in order to obtain information about the carbohydrate composition of the outer surface of D. collini. Concanavalin A bound to the surface of the cell body and tentacle shaft as a dense, particulate layer (80 nm thick) but thinned to 13–16 nm over the surface of the knob. Wheat germ agglutinin‐treated cells also displayed a heavy, electron‐dense layer (128 nm thick) that surrounded the main cell body and tentacle shaft, but only scattered patches of bound wheat germ agglutinin were observed on the surface of the knob. Discophrya treated with Helix agglutinin or peanut agglutinin appeared similar to control cells. Suctorians were treated with lectins in vivo in an attempt to inhibit capture and ingestion of their prey, Tetrahymena pyriformis, by masking prey receptor sites on the knob. Concanavalin A and, to a lesser degree, wheat germ agglutinin, successfully inhibited attachment of the prey organism. Helix agglutinin and peanut agglutinin had little effect on prey capture.
Cellulose Detected in the Stalk of Protostelium irregularis (Eumycetozoea)1
Authors: BLANTON R. L. , CHANZY H. D.
Published: May 2007

The stalk of Protostelium irregularis (Eumycetozoea) has been studied with light and electron microscopy and selected‐area electron diffraction. The stalk is positively birefringent and fibrillar. Diffraction patterns obtained from stalks indicate that crystalline cellulose I is one component of the stalk.
Identification of the Meiotic Division of Malarial Parasites
Authors: SINDEN R. E. , HARTLEY R. H.
Published: May 2007

Zygotes of Plasmodium berghei were cultured 15–25 h in vitro to yield mature infective ookinetes. Samples taken in the first 5 h of culture were examined by electron microscopy. Meiotic figures were detected in the nuclei of the zygotes. Threadlike leptotene chromatids (chromosomes) condensed from attachment plaques on the nuclear envelope; chromatid pairing followed (zygotene), with synaptonemal complexes subsequently appearing (pachytene). These complexes persisted into metaphase but dissociated when the chromatids rapidly decondensed during anaphase. At telophase of the first meiotic division the kinetochores were retracted toward two small spindle complexes, which were found at widely separated poles in the nuclear envelope. The observations are consistent with a haploid genome of 8–10 chromosomes.
Symposium on “Symbiosis in Protozoa”: Introductory Remarks1,2
Authors: LEE JOHN J. , CORLISS JOHN O.
Published: May 2007

ABSTRACT.

Attention, perhaps overdue, is drawn to the extent and significance of endosymbionts (xenosomes sensu lato) in the cytoplasm and nuclei of many protozoa from diverse taxonomic groups. Even more importantly, recent advances in the study of such intimate associations are reviewed and discussed and their impact on broader problems of cell biology and evolution are stressed. Workers inside and especially outside the fields of protozoology and parasitology have often neglected such data, failing to appreciate their relevance to significant problems in their own fields of investigation. The major topics covered by speakers in the Symposium (to which this paper serves only as an introduction) include the following, in order of their presentation: terminology for the symbiont‐host relationship and a brief overview of the field; the evolutionary problem of the origin of contemporary associations, including cell organelles such as mitochondria and plastids; the adaptive value of endosymbionts to their protozoan hosts; mechanisms of establishment, maintenance, and integration of such foreign bodies/invaders in their unicellular eukaryotic host cells; and the extent of algal and bacterial endosymbioses in diverse protozoan groups. In all papers, the principal relatively well studied complexes used as examples are the following: various kinds of algae in the larger foraminifera and in ciliates, radiolarians, and acantharians; the several types of bacteria in the cytoplasm of Amoeba and of Pelomyxa; the endonuclear bacterial symbionts of Paramecium; the cytoplasmic prokaryotes in Paramecium and in Parauronema; and the methanogenic bacteria of certain ciliates.
Establishment, Maintenance, and Integration Mechanisms of Endosymbionts in Protozoa1
Authors: REISSER WERNER , MEIER RENATE , GÖRTZ HANS‐DIETER , JEON KWANG W.
Published: May 2007

ABSTRACT.

Important progress has been made in recent years towards better understanding of the establishment and maintenance of endosymbiosis in protozoa and of the eventual integrative mechanisms involved. Still, many problems remain to be investigated more thoroughly. In this paper, while treating and reviewing the subject broadly, particular and more detailed attention is given to three selected systems: endonuclear symbiosis by Holospora bacteria in Paramecium; algal (Chlorella) relationships with the “green”Paramecium (P. bursaria) as host; and the rod‐shaped bacteria found in the cytoplasm of Amoeba proteus. Data concerning the physiology of food vacuoles, membrane transport, photobehavior, recognition specificity, enzyme activity, and the like are presented and reviewed and discussed in light of the growing literature on the overall subject of “endocytobiology.” Emphasized is the complicated network of interactions between symbiotic partners and the importance of the development of integrative mechanisms in the evolution of the many intimate associations known at the cellular level today.
Symposium on “Protozoan Ecology”: The Role of Protozoa in Litters and Soils1
Authors: BAMFORTH STUART S.
Published: May 2007

Soil is the focus of organic matter turnover in terrestrial ecosystems and is an interstitial mosaic of microsites composed of particle aggregates and pore spaces, where transformation, decomposition, mineralization, and humification of organic matter takes place. Microorganisms and animals are scattered discontinuously in these microsites. Microarthropods and larger fauna increase the rate and amount of mineralization by comminution of organic matter and by redistribution of microsites through movements of earthworms and large arthropods; however, mineralization and return of nutrients to plants occurs in the community of bacteria, fungi, protozoa, and nematodes living in the water films covering aggregates and filling pore spaces. Protozoa, especially small amoebae, are important bacterial grazers because they can enter tiny spaces unavailable to nematodes. The latter graze bacteria, fungi, and protozoa. Protozoan and nematode predation increase the amounts of soluble nutrients and decrease the competitive abilities of bacteria, thus making these nutrients more available to plants. Protozoa enhance nutrient recycling out of proportion to their biomass.