bluuebunny/crossref_metadata_2025 huggingface dataset:
Oral Monokinetids in the Free‐Living Haptorid Ciliate Enchelydium polynucleatum (Ciliophora, Enchelyidae): Ultrastructural Evidence and Phylogenetic Implications1
Authors: FOISSNER WILHELM , FOISSNER ILSE
Published: May 2007

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

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

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

ABSTRACT.

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

ABSTRACT.

It is generally accepted that in symbiotic systems involving algal species as cellular endobionts there is some positive benefit to the host organisms. In this paper special consideration is given to the larger foraminifera, protozoa that serve as very useful model systems for the study of aspects of inter/intracellular integration and adaptation—living, as they do, in nutrient‐limited but well illuminated shallow tropical seas and containing endosymbiotic algae in abundance. A considerable amount of information is now available on physiological as well as morphological adaptations of the host species to pigmented protists representing diverse algal divisions (phyla). Brief mention is also made of bacterial endosymbionts of certain ciliates.
Protozoa in Planktonic Food Webs1,2
Authors: PORTER KAREN G. , SHERR EVELYN B. , SHERR BARRY F. , PACE MICHAEL , SANDERS ROBERT W.
Published: May 2007

Protozoa are now being recognized as important members of planktonic food webs. This is due to the inclusion of microbial links in our paradigm of trophic relationships. Heterotrophic microflagellates and ciliates are major grazers of bacteria. They can stimulate production through nutrient recycling and can transform microbial production into larger particles, which are then available for macroconsumers. In this paper we add new groups, the small (< 20 μm) ciliates and myxotrophic flagellates, to the planktonic food web.
Functional Groups in the Protozoa: Roles in Differing Ecosystems1,2
Authors: PRATT JAMES R. , CAIRNS JOHN
Published: May 2007

Feeding habits of freshwater protozoa were used to group species into functional, trophic groups. Community structure in differing ecosystems was examined in relation to the number of species occurring in the functional group categories. Six wetland ecosystems and a large river ecosystem were studied. Changes in community structure during the colonization of artificial substrates were also examined. Changes during colonization were studied in a mesotrophic lake, in low‐order streams, and in laboratory microecosystems. In the latter case, the response of colonizing communities to a heavy metal toxicant was studied. All communities studied were dominated by bactivorous‐detritivorous species and, to a lesser extent, by photosynthetic species. The chief functional role of substrate‐associated protozoans appears to be the processing of dead organic matter and its associated bacterial flora. Functional groups utilizing resources other than detrital or mineral nutrients (saprotrophs, algivores, omnivores, and predators) were always minor community components. Colonizing communities were often dominated by photosynthetic species during early colonization stages but were again dominated by bactivorous‐detritivorous species at species equilibrium. Low levels of toxicant (Cd) reduced numbers of both photosynthetic and bactivorous‐detritivorous species. Higher toxicant levels virtually eliminated photosynthetic species and reduced bacterial detritivores by over one‐half. Roles of protozoan species in ecosystems are closely tied to the processing of detritus and the recycling of mineral nutrients. Enumeration of individuals in functional categories is proposed as a simplified method for studying the abundance and activity of protozoa in ecosystems. Examination of changes in functional group composition and the relationship of functional group abundances to rates of carbon processing are suggested for studies of the importance of protozoa to the flow of energy and materials in ecosystems.
Structural Alteration of the Membrane of Erythrocytes Infected with Plasmodium falciparum1
Authors: AIKAWA MASAMICHI , UDEINYA IROKA J. , RABBEGE JOHN , DAYAN MICHAEL , LEECH JAMES H. , HOWARD RUSSELL J. , MILLER LOUIS H.
Published: May 2007

Human erythrocytes infected with five strains of Plasmodium falciparum and Aotus erythrocytes infected with three strains of P. falciparum were studied by thin‐section and freeze‐fracture electron microscopy. All strains of P. falciparum we studied induced electron‐dense conical knobs, measuring 30–40 nm in height and 90–100 nm in diameter on erythrocyte membranes. Freeze‐fracture demonstrated that the knobs were distributed over the membrane of both human and Aotus erythrocytes. A distinct difference was seen between the intramembrane particle (IMP) distribution over the knobs of human and Aotus erythrocyte membranes. There was no change in IMP distribution in infected human erythrocyte membranes, but infected Aotus erythrocytes showed an aggregation of IMP over the P face of the knobs with a clear zone at the base. This difference in IMP distribution was related only to the host species and not to parasite strains. Biochemical analysis demonstrated that a higher proportion of band 3 was bound to the cytoskeleton of uninfected Aotus erythrocytes than uninfected human erythrocytes after Triton X‐100 extraction. This may account for the different effects of P. falciparum infection on IMP distribution in the two different cell types.
The Mitochondrion of Plasmodium falciparum Visualized by Rhodamine 123 Fluorescence1
Authors: DIVO A. A. , GEARY T. G. , JENSEN J. B. , GINSBURG H.
Published: May 2007

Rhodamine 123 (Rh 123) has been used to probe the functional status of the mitochondrion present within the asexual, intraerythrocytic stages of the malarial parasite Plasmodium falciparum. This cationic fluorescent dye accumulates specifically in negatively charged cellular compartments, such as mitochondria. Using epifluorescence microscopy the development of what appears to be a single mitochondrion has been followed through the intraerythrocytic cycle. Mitochondrial development progresses from a fine thread‐like organelle that becomes longer and eventually branched. Each daughter merozoite receives a branch or piece of the parent organelle. Cytoplasmic Rh 123 accumulation was also observed, indicating that there exists a transmembrane potential across the outer plasma and parasitophorous vacuolar membranes of the parasite. The effects of uncouplers (protonophores), ionophores, and inhibitors were examined by monitoring Rh 123 accumulation and retention. Our results demonstrate that the mitochondrion of P. falciparum actively maintains a high transmembrane potential, the function of which is as yet undefined.
Invasion and Early Development of Sarcocystis muris (Apicomplexa, Sarcocystidae) in Tissue Cultures1
Authors: ENTZEROTH ROLF
Published: May 2007

Ultrastructural observations on the invasion and early development of merozoites (bradyzoites) of Sarcocystis muris in Madin‐Darby canine kidney (MDCK) cells are presented. Invading merozoites cause the host cell plasmalemma to invaginate; they form a membrane junction (moving junction) and move into the host cell where they are enclosed in a primary parasitophorous vacuole (PV). Within 30–45 min after becoming intracellular, merozoites begin to vacate the newly established primary PV and move, forming a new membrane junction, into a secondary PV. Simultaneously with the movement of the parasite, the contents of dense granules in the apical part of the merozoites are shed by exocytosis into the lumen of the developing secondary PV. A lamella of the endoplasmic reticulum of the host cell becomes attached to the PV membrane, forming a PV limited by three host cell membranes.
Nuclear Behavior During Reconjugation in Euplotes patella (Ciliophora, Hypotrichida)1
Authors: SATO KATSUYUKI
Published: May 2007

Nuclear behavior during reconjugation and the ultimate fate of the ex‐reconjugants were followed after induction of reconjugation in Euplotes patella. An exconjugant could reconjugate with a vegetative cell or with another exconjugant. Exconjugants at an early stage of macronuclear development (oval macronuclear anlagen) did not reconjugate frequently whereas exconjugants at a late stage of macronuclear development (rod‐like macronuclear anlagen) reconjugated frequently. In all cases, the micronucleus underwent normal meiosis and other nuclear changes. After reconjugation, a new macronuclear anlage and a new micronucleus were formed normally, so that there were two kinds of macronuclear anlagen in the exconjugants, an old and a new. The old rod‐shaped anlage did not disappear after the differentiation of a new one, but it was broken up into several fragments. While the survival rate after normal conjugation was 78%, it was 0–20% after reconjugation. These results suggest that the micronuclei of exconjugants can act as germ nuclei even at a very early stage and that reconjugation, unlike conjugation, is harmful to the cell.
Nutrition of the Trypanosomatids Crithidia acanthocephali and C. harmosa. Ribose and Adenosine: Substrates for C. acanthocephali1
Authors: ROITMAN ISAAC , ANGLUSTER JAYME , FIORINI JOÀO EVANGELISTA
Published: May 2007

Crithidia acanthocephali and C. harmosa share the same minimal nutritional requirements as the standard C. fasciculata. Crithidia acanthocephali is exceptional, however, in that it utilizes D‐ribose, free or as nucleoside (e.g. adenosine), as carbon source.
Effects of Cations on Phagocytosis in the Ciliate Pseudomicrothorax dubius1
Authors: PECK ROBERT K. , DUBORGEL FRANÇOISE
Published: May 2007

Various cations have been examined for their effects on phagocytosis. Media with high [Ca2+] and low [K+] favor phagocytosis, which is inhibited in media with high [K+], [Rb+], or [Ba2+] and low [Ca2+]. Microscopical observations of inhibited cells demonstrate that swimming behavior is not modified but they cannot perform the initial step of phagocytosis, attachment to food; when Ca2+ is added, cells attach to and ingest food, demonstrating rapid reversal of inhibition. Attachment is shown to be a linear function of the ratio [K+]/[Ca2+]1/2 or [Rb+]/[Ca2+]1/2 in the medium. The Ca2+ influx inhibitor Verapamil blocks attachment, as does La3+; the latter is believed to compete with Ca2+ for access to the Ca2+ channel. Likewise, treatment of cells with media containing no added Ca2+ inhibits attachment, and addition of 10 μM Ca2+ allows 90% of these cells to attach to and ingest food. The ionophore A23187, known to transport Ca2+ into a wide variety of cells, provokes lysosomal streaming movements typical of attachment. Based upon these observations, Ca2+ influx plays an essential role in attachment; K+ efflux also appears to be necessary since tetraethylammonium chloride blocks attachment. Treatment of cells with Tetrodotoxin, an inhibitor of Na+ transport, or suspending them in media containing no added Na+ does not affect attachment or ingestion, indicating that Na+ is not implicated in these processes. An hypothesis is presented which implicates Ca2+ in both direct adhesion and exocytosis phenomena during attachment.
Effects of Chemical Substances on Rate of Locomotion in the Amoeba Mayorella penardi1
Authors: OSHIMA NORIKO , TAKEDA FUMIKAZU , ISHII KEIICHI
Published: May 2007

The relationship between the locomotive velocity of amoeba which had not been fed for 24 h and the concentration of the test solutions was examined. With solutions of L‐amino acids, protein substances, and alcian blue 8GS, an increase in velocity began at very low concentrations, reaching a maximum at a higher concentration and as the concentration increased further, the velocity fell to zero. In contrast, no increase was observed with D‐glutamic acid and β‐alanine. Moreover, the velocity of well fed amoebae did not increase significantly even in L‐amino acid solution. These results may suggest a correlation between orthokinesis and amoeboid phagocytosis.
Klossiella (Apicomplexa, Klossiellidae) in Petaurid and Macropodid Marsupials in Australia1
Authors: BARKER IAN K. , MUNDAY BARRY L. , HARTLEY WILLIAM J.
Published: May 2007

Six new species of Klossiella are described in the kidneys of Australian marsupials: Klossiella rufogrisei in Bennett's Wallaby, Macropus rufogriseus; Klossiella rufi in the Red Kangaroo, Macropus rufus; Klossiella thylogale in the Red‐Bellied or Tasmanian Pademelon, Thylogale billardierii; Klossiella beveridgei in the Spectacled Hare‐Wallaby, Lagorchestes conspicillatus; Klossiella bettongiae in the Tasmanian Bettong, Bettongia gaimardi; and Klossiella schoinobatis in the petaurid Greater Glider, Petauroides volans. It is concluded that the genus Klossiella has radiated widely among Australian marsupials, and that since it is present in American marsupials, it may have an ancient association with the subclass.
Chemosensory Responses in Tetrahymena: The Involvement of Peptides and other Signal Substances1
Authors: LEICK VAGN , HELLUNG‐LARSEN PER
Published: May 2007

Starved Tetrahymena thermophila (or cells growing in Holz's defined medium) are attracted by a chemosensory response to complex peptide mixtures as proteose peptone, yeast extract, and extracts of blood platelets containing platelet‐derived growth factor. Starved cells are also significantly attracted by mixtures of amino acids and of nucleosides of Holz's defined medium; however, no individual amino acid or nucleoside could be identified as the major chemo‐attractant.

The positive chemosensory response can be abolished by cycloheximide (CHX) but is insensitive to actinomycin D and puromycin, possibly indicating that de novo RNA and protein synthesis are not necessary for a change in chemosensory behavior. Three mutants resistant to CHX show normal response in the presence of the drug.

The possible role of peptides as naturally occurring food signals of Tetrahymena is discussed.
Nonrandom Localization of DNA Sequences in the Crescent Micronucleus of Tetrahymena1
Authors: KARRER KATHLEEN M.
Published: May 2007

The premeiotic micronucleus of Tetrahymena thermophila elongates parallel to the long axis of the cell. In fixed cells one end of this crescent micronucleus appears thicker than the other, and either end may be oriented toward the anterior of the cell. Three families of repeated DNA sequences have been localized in the crescent micronucleus by in situ hybridization. Two micronucleus‐specific sequences hybridize all along the crescent, but preferentially toward the ends. A macronucleus‐retained sequence hybridizes preferentially to the half of the micronucleus at the thick end. Thus the arrangement of DNA sequences in the crescent micronucleus is nonrandom.
Movement of Naegleria fowleri Stimulated by Mammalian Cells In Vitro1
Authors: CLINE MICHAEL , CARCHMAN RICHARD , MARCIANO‐CABRAL FRANCINE
Published: May 2007

ABSTRACT. Naegleria fowleri amebae, but not those of N. australiensis, N. gruberi, or N. lovaniensis, demonstrated enhanced motility when placed in proximity to mammalian cells. Amebae of nonpathogenic species of Naegleria, however, were more motile in cell culture medium than the amebae of N. fowleri. The locomotory response of highly pathogenic mouse‐passaged N. fowleri amebae to nerve cells was greater than axenically cultured amebae. The enhanced mobility elicited by whole nerve cells or disrupted nerve cells was not directed migration but chemokinetic. Naegleria fowleri responded to disrupted neuroblastoma cells more vigorously than to disrupted African green monkey kidney (Vero) cells.
Sequence of the Small Subunit Ribosomal RNA Gene from the Hypotrichous Ciliate Euplotes aediculatus1
Authors: SOGIN M. L. , SWANTON M. T. , GUNDERSON J. H. , ELWOOD H. J.
Published: May 2007

ABSTRACT. We have determined the complete nucleotide sequence of the coding region of the small subunit rRNA gene of the hypotrichous ciliate Euplotes aediculatus. It is 1882 nucleotides long and contains several inserts not present in the small subunit rRNA genes of the hypotrichs Oxytricha nova and Stylonychia pustulata. A comparison of the sequences suggests that E. aediculatus is much less closely related to these other two hypotrichs than they are to each other. Although the gene sequence of E. aediculatus is drifting more rapidly than those of these other two species, its faster evolutionary clock is not enough to account for the degree of difference between them.
Poly(A)‐Containing RNA from the Spleens of Mice with Chagas’Disease Triggers In Vitro Macrophage Resistance to Trypanosoma cruzi1
Authors: BERTOLINI M. C. , DE LUCCA F. L.
Published: May 2007

ABSTRACT. Mouse peritoneal macrophages exposed to the RNA from the spleens of mice infected with Trypanosoma cruzi (iRNA) exhibit enhanced resistance to this parasite. The poly(A)‐containing iRNA was found to be the active fraction. No such activity was observed in macrophages incubated with RNA from normal mice (nRNA) or with synthetic poly A.
Study of an Amoeboflagellate Isolated from the Nasal Mucosa of Man
Authors: MASCARÓ M. L. , MASCARÓ M. C. , OSUNA A. , PÉREZ M. I. , GONZÁLEZ‐CASTRO J.
Published: May 2007

ABSTRACT. This paper examines the biology, morphology, and pathogenicity for mice of an amoeboflagellate isolated from human nasal mucosa. The biological and morphological relationships of this isolate with the amoebae (Lobosea) and the true slime molds (Eumycetoza) are discussed though the taxonomic affinities of the organism have not been determined.
Morphological and Biochemical Correlates in the Characterization of Sarcocystis spp.1
Authors: O'DONOGHUE P. J. , ADAMS M. , DIXON B. R. , FORD G. E. , BAVERSTOCK P. R.
Published: May 2007

ABSTRACT. Isoenzyme electrophoretic techniques were applied to the characterization of seven Sarcocystis spp. that had been identified by conventional morphological studies. Cystozoites were harvested from macroscopic cysts from sheep, cattle, and mice and from microscopic cysts from sheep, cattle, and goats. Soluble cystozoite extracts were subjected to cellulose acetate gel electrophoresis and characterized at 15 of the 39 enzyme loci examined. Genetic relationships among isolates were examined by simple phenetic clustering. Two different morphological types of macroscopic cysts from sheep, identified as S. gigantea (syn. S. ovifelis) and S. medusiformis, consistently differed at 40% of the loci examined. Such genetic divergence confirms their separate morphotypic classification. Both differed from microscopic cyst isolates from sheep at 87% of the loci examined; however, two different morphotypes of microscopic cysts were found in the sheep sampled (thick‐walled and thin‐walled cysts). Until sufficient numbers of each type can be isolated and examined separately, both were regarded as belonging to the species S. tenella (syn. S. ovicanis). Macroscopic and microscopic cysts from cattle consistently differed at 80% of the loci thereby supporting their separate classification as S. hirsuta (syn. S. bovifelis) and S. cruzi (syn. S. bovicanis), respectively. Isolates from goats (microscopic cysts identified as S. capracanis) differed from S. tenella and S. cruzi at 20% and 47% of the loci, respectively. All macroscopic cyst isolates from the various host animal species (including S. muris from mice) differed from each other at nearly all loci. Isoenzyme electrophoretic techniques therefore provided genetic evidence supporting the classification of these various Sarcocystis spp. by their morphological characteristics.
Effects of Mitochondrial Inhibitors on Intraerythrocytic Plasmodium falciparum in In Vitro Cultures1
Authors: GINSBURG H. , DIVO A. A. , GEARY T. G. , BOLAND M. T. , JENSEN J. B.
Published: May 2007

ABSTRACT. Malarial parasites infecting mammalian hosts are considered to be homolactate fermentors at their asexual intraerythrocytic developmental stage; however, existing ultrastructural and biochemical evidence suggest that their acristate mitochondria could be involved in energy metabolism. In the present study, inhibitors of mitochondrial function including compounds which act on NADH and succinate dehydrogenases, electron transport and mitochondrial ATPase, as well as uncouplers, were found to inhibit the growth and propagation of the human parasite Plasmodium falciparum in in vitro cultures at concentrations that specifically affect mitochondrial functions. Direct measurement of parasite protein and nucleic acid synthesis in synchronized cultures showed that throughout the parasite life cycle both processes were inhibited, the latter process being more sensitive. These results strongly suggest that intraerythrocytic malarial parasites require mitochondrial energy production.
Photobehavior of the Ciliated Protozoon Loxodes: Taxic, Transient, and Kinetic Responses in the Presence and Absence of Oxygen1
Authors: FENCHEL TOM , FINLAY BLAND J.
Published: May 2007

ABSTRACT. Behavioral responses to light at different oxygen tensions were studied in the ciliate Loxodes striatus. In the absence of O2 it does not react to light. In the presence of O2 it reacts to light as if the pO2 had been further increased, with the induction of positive geotaxis, a transient phobic response, and finally with a permanent kinetic response (increased swimming velocity and a decreased rate of tumbling). Cells treated with cyanide behave as cells in an anoxic environment and do not react to light. It is concluded that the light response is due to the photochemical production of oxygen radicals and that the sensory receptors for O2 and for light are identical. The three types of behavioral response (geotaxis, transient, and kinetic responses) are discussed in terms of their adaptive significance for the orientation of Loxodes in the natural environment.
Oxygen Perception and O2 Toxicity in the Freshwater Ciliated Protozoon Loxodes
Authors: FINLAY B. J. , FENCHEL T. , GARDENER S.
Published: May 2007

ABSTRACT. Loxodes reached peak abundance close to the oxic‐anoxic boundary (O2 5% atm) in two lakes, in test tube cultures, and in glass chambers with horizontal O2 gradients. Vertical profiles of CO2, pH, sulfide, and Fe2+ in a lake were not closely related to Loxodes abundance. In a laboratory experiment, Loxodes followed a retreating source of O2 and was repelled by a high pO2. This behavior was sustained when cells simultaneously swam up or down gradients of both CO2 and pH. Aggregation of cells was abolished by KCN (10‐4‐10‐6 M). Sodium azide (10‐1‐10‐4 M) had no effect and 2,4‐DNP sharpened the aggregation. Rotenone, Antimycin A, and HOQNO had no obvious effect. Cytochrome oxidase is probably the oxygen receptor. Loxodes striatus contained low activities of superoxide dismutase and catalase. Extracellular production of superoxide (O‐2) and hydrogen peroxide (H2O2) were probably not responsible for the exclusion of Loxodes from water with a high pO2. Continuous exposure of Loxodes to oxygen at normal atmospheric pressure at 10°C led to 50% mortality in 10 days. Cells left free to swim in an oxygen gradient doubled their number in the same period. Light exacerbated the toxic effects of O2. Behavioral responses to the dissolved oxygen tension probably controlled the spatial distribution of Loxodes.
Pellicular Ultrastructure and Euglenoid Movement in Euglena ehrenbergii Klebs and Euglena oxyuris Schmarda1
Authors: SUZAKI T. , WILLIAMSON R. E.
Published: May 2007

ABSTRACT. The pellicular ultrastructure of Euglena ehrenbergii and Euglena oxyuris is examined for differences that might account for their very different motile activity. Their general ultrastructure is closely similar, but the continuity between adjacent pellicular strips found in E. oxyuris would severely restrict strip sliding and contribute to this species’very limited cell‐shape changes. The strips of E. ehrenbergii have plate‐like projections, whose constant orientation is consistent with strips sliding without deforming obliquely on cell rounding. Some variations and constant features in pellicular ultrastructure are noted and discussed in regard to the sliding strip mechanism for euglenoid shape changes.
Leishmania mexicana pifanoi: Analysis of the Antigenic Relationships Between Promastigotes and Amastigotes by Gel Diffusion, Immunoelectrophoresis, and Immunoprecipitation1
Authors: PAN ALFRED A.
Published: May 2007

ABSTRACT. The antigenic relationships between Leishmania mexicana pifanoi promastigotes, axenically grown amastigotes, and amastigotes isolated from the footpads of infected hamsters or from a J774 macrophage cell line were studied by three serologic methods. Amastigote and promastigote antigens were disrupted by freeze‐thawing of intact cells in a lysis buffer. Antisera were prepared in rabbits by repeated subcutaneous inoculations of the parasite antigens in complete Freund's adjuvant and were tested against the homologous and heterologous antigens in a series of gel diffusion experiments. Negative results were obtained in all control experiments. In each instance, the homologous antigen‐antiserum reactions yielded the largest numbers of precipitin lines. A pattern of cross‐reactivity was also observed in the heterologous systems. Results indicated that the amastigote and promastigote forms had unique and common antigens. The two parasite antigen‐antiserum systems were also examined by immunoelectrophoresis. Qualitative and quantitative differences between the promastigote and amastigote antigens were readily demonstrable by this technique. Results indicated that each parasite form had specific and many common antigens. In the homologous system, major proteins, with molecular weights (MW) of 23, 52, and 68 kd, were demonstrated in the promastigotes by immunoprecipitation of lactoperoxidase‐catalyzed radioiodinated cells. In a similar (homologous) system, axenically grown amastigotes were found to contain three proteins with MW of 38, 70, and 74 kd and, therefore, different from those demonstrated for the promastigotes. All the results suggested that the three amastigote stages of different origins are antigenically similar to one another, but differ from the promastigote forms.
Purification and Partial Characterization of the H Immobilization Antigens of Tetrahymena thermophila1
Authors: DOERDER F. P. , BERKOWITZ M. S.
Published: May 2007

ABSTRACT. The H immobilization antigens specified by the SerH locus of Tetrahymena thermophila have been purified by a procedure utilizing acid fractionation, ammonium sulfate precipitation, gel filtration, and ion exchange chromatography. Purified antigen migrates as a single band on SDS‐PAGE and IEF. Molecular weights of the four allelic H antigens range from 44,000 to 52,000, and isoelectric points range from 4.1 to 4.5. No carbohydrate was detected.
Kinetics of the DFPase Activity in Tetrahymena thermophila1
Authors: LANDIS WAYNE G. , HALEY MARK V. , JOHNSON DENNIS W.
Published: May 2007

ABSTRACT. Crude homogenates of the ciliate protozoon, Tetrahymena thermophila, can hydrolyze the potent acetylcholinesterase inhibitors O, O‐diisopropylphosphorofluoridate (DFP) and O‐1,2,2‐trimethylpropylmethylphosphonofluoride (soman). Characterization of the enzymatic activity of the homogenate has been performed. The DFPase operates over a pH range of 4 to 10 and an ionic range of 0–500 mM NaCl. Rate of reaction increases three‐to four‐fold from 25°C to 40°C and is still present at 55°C. These results indicate that the enzymatic activity operates over a broad range of environmental conditions, making it an attractive material for use in the detoxification and detection of organofluorophosphates. DFPases may be important in the metabolism of naturally occurring organophosphates.
Economic Mass Cultivation of Paramecium tetraurelia on a 200‐Liter Scale1
Authors: SCHÖNEFELD ULRICH , ALFERMANN A. WILHELM , SCHULTZ JOACHIM E.
Published: May 2007

ABSTRACT. A new and inexpensive medium is described for axenic mass cultivation of Paramecium tetraurelia stock 51s and the double mutant pawn A/pawn B. Skim milk powder is the major carbon and nitrogen source in this medium. Growth characteristics (proliferation rate, final cell density, and cell size) are similar to those observed with other axenic culture media. Cultures were run in one‐liter erlenmeyer flasks, a 20‐liter, and a 250‐liter airlift bioreactor. The yield of a large bioreactor is 750 g (wet wt.) Paramecium or 5 × 109 cells. This easy, economical culture technique will greatly facilitate the use of Paramecium as a model organism for extensive biochemical studies.
Spontaneous Selfing (Intraclonal Conjugation) in the Ciliate Euplotes patella Syngen 2 Takes Place without a Change in Mating Type Expression
Authors: AKADA RINJI
Published: May 2007

ABSTRACT. Cells of Euplotes patella syngen 2 have been found to excrete mating‐type‐specific gamones (mating‐inducing factors) into the surrounding medium. In strains of E. patella syngen 2, intraclonal conjugation (selfing) sometimes occurred spontaneously. Cell‐free fluids of clonal cultures in which spontaneous selfing occurred were not effective in inducing homotypic pair formation in other cultures of the same mating type as the culture from which the cell‐free fluids were derived. This indicates that selfing cultures produce only those gamones expected of their own mating types. This result suggests that spontaneous selling in E. patella syngen 2 is not due to change of mating type expression. The possible mechanisms for spontaneous selfing in E. patella syngen 2 are discussed.
Effect of Cytochalasin B on the Cytokinesis of Thuricola folliculata (Ciliophora, Peritrichida)1
Authors: EPERON SEMONE , DE HALLER GÉRARD
Published: May 2007

ABSTRACT. Binary fission of the sessiline loricate peritrich Thuricola folliculata was examined by light microscopy. Cytokinesis, which occurs in the oral‐aboral median plane, is 35‐40 min in duration. Cytochalasin B (CB) was used at final concentrations of 50–100 μg/ml in dimethyl sulfoxide (DMSO). A transition point occurs at about 20 min after the beginning of binary fission and about 10 min before cytokinesis. In most cases, 50 μg/ml and 100 μg/ml CB added to cells before the transition point resulted in delays of cytokinesis which were significant compared to DMSO controls; sometimes, cytokinesis was blocked completely. If added after the transition point, CB had no effect on cells.
Lipidic Vacuoles in Plasmodium knowlesi Erythrocytic Schizonts
Authors: BANNISTER L. H. , MITCHELL G. H.
Published: May 2007

ABSTRACT. Electron microscopy of schizont development in erythrocytic Plasmodium knowlesi has revealed that spheroidal vacuoles 250 nm in diameter with semi‐dense contents appear at the periphery of the parasite prior to the budding of merozoites. When treated with non‐polar solvents, their contents are completely extracted, and after fixation in tannic‐glutaraldehyde they contain regular lamellae with a periodicity of 5.5 nm. Both of these reactions are typical of lipids. Some of these structures are associated with phagosomal vacuoles which may contribute to their lamellae. They disappear at the onset of merozoite formation, but membranous whorls of various sizes continue to be associated with the schizont surface during budding of merozoites. It is suggested that the lipidic vacuoles are a source of preformed lipid which can be utilized rapidly during the generation of merozoites.
Gibbsia archiuli (Apicomplexa, Eucoccidiorida) n. g., n. sp. from the Millipede Archiulus moreleti
Authors: LEVINE NORMAN D.
Published: May 2007

ABSTRACT. Gibbsia archiuli n. g., n. sp. (Eucoccidiorida, Adeleidae) is named for the apicomplexan protozoon described by Gibbs (1952) from the blood cells of the South African garden millipede Archiulus moreleti. Merogony, gamogony, and sporogony all take place in the host's blood cells. The oocysts contain four sporocysts, each with one sporozoite. The microgametes are not flagellated.
Analysis of Antigens from Membrane and Soluble Fractions of Entamoeba histolytica
Authors: MATHEWS H. M. , MOSS D. M. , VISVESVARA G. S.
Published: May 2007

ABSTRACT. Axenic cultures of Entamoeba histolytica strains HK‐9, HM‐1, and Rahman were fractionated to provide plasma membranes, internal, vesiculated membranes, and a soluble cytosol. Each particulate fraction was solubilized and all fractions were analyzed by techniques designed to demonstrate molecular complexity and serologic reactivity. The cytosol contained more antigenic moieties than either membrane fraction; however, the antigens associated with the membranes had very high reactivity and lower nonspecific activity than the cytosol.
Pre‐Erythrocytic Development and Associated Host Responses to Haemoproteus meleagridis (Haemosporina: Haemoproteidae) in Experimentally Infected Domestic Turkeys12
Authors: ATKINSON CARTER T. , GREINER ELLIS C. , FORRESTER DONALD J.
Published: May 2007

ABSTRACT. Two generations of pre‐erythrocytic schizogony occurred in skeletal and cardiac muscle of domestic turkeys infected with sporozoites of Haemoproteus meleagridis. First generation schizonts reached maturity approximately five days post‐inoculation (DPI) and developed in capillary endothelial cells and myofibroblasts. The schizonts ranged from 12 to 20 μm in diameter and produced long (5–6 μm), slender merozoites. Early second generation schizonts were first detected in capillary endothelial cells between 5 and 8 DPI. They were cylindrical and ranged in size from 5 to 8 μm in diameter and up to 28 μm in length. Second generation schizonts which reached maturity by 17 DPI were surrounded by a thick, hyaline wall and were packed with numerous spherical merozoites less than 1 μm in diameter. Mature megaloschizonts were fusiform, ranged from 30 to 113 μm in diameter, and extended as much as 465 μm along the long axis of muscle fibers. Merozoites developed as buds from cytomeres that formed between 8 and 14 DPI. Infected turkeys developed a moderate to severe myositis within 5 DPI and were lame in one or both legs. The myositis was associated with the necrosis of scattered groups of muscle fibers. Muscle fibers surrounding mature megaloschizonts were swollen and hyaline. Megaloschizonts were surrounded occasionally by fibroblasts and infiltrates of mononuclear cells. The morphology and site of development of mature megaloschizonts of Haemoproteus meleagridis are contrasted with those of other avian haemosporidians.
Rumen Ciliate Fauna of Some Brazilian Cattle: Occurrence of Several Ciliates New to the Rumen, Including the Cycloposthid Parentodinium africanum1
Authors: DEHORITY BURK A.
Published: May 2007

ABSTRACT. Parentodinium africanum was observed in rumen contents of four Brazilian cattle and constituted 4.4, 0.9, > 0.1, and 10.0% of the total ciliates. This appears to be the first observation of the family Cycloposthiidae in the rumen habitat. Blepharoconus krugerensis, previously observed in the intestines of the elephant, and an unknown species of ciliate with many characteristics similar to the family Paraisotrichidae were each observed in a single animal. A new subspecies, Diplodinium flabellum laterospinatum n. subsp., is also described. Total number of ciliates per ml of rumen contents ranged from 9.0 to 51.2 × 104 and included an overall total of 55 species and 4 subspecies.
Effect of Extracellular pH on Motility and K+‐Induced Ciliary Reversal in Paramecium caudatum1
Authors: DOUGHTY MICHAEL J.
Published: May 2007

ABSTRACT. Paramecium caudatum, reared on bacterized hay infusions at pH 6.5 to 6.9, were washed into various buffered solutions containing 0.016 mM CaCl2 and a pH of 3.5 to 10.4. Solutions of pH 4.5 to 9.5 support strong swimming of the cells for at least 24 h. At pH values acid to the culture medium, cells show an increasing frequency of spontaneous ciliary reversal episodes (“avoiding reactions”). Uninterrupted forward swimming is usually observed over the pH range of 7.1 to 8.5, and above pH 8.5, forward motion is interrupted by circular swimming. For all pH values tested, transfer of cells to a more acidic test solution than the solutions into which they were washed (adaptation solution) usually induced short duration, periodic ciliary reversal behavior. With transfer to a more alkaline test solution than the adaptation solution, the cells shift from forward left spiralling motion to forward right spiralling motion. With decreasing pH, the cells show progressively less sensitivity to KC1 stimulation, and at pH values of less than 5.0, cells fail to show significant ciliary reversal response to any KC1 concentration tested (1 ‐ 128 mM). At alkaline pH values and higher KC1 concentrations, the cells show very pronounced ciliary reversal behaviors but usually fail to regain forward swimming behavior.
In Vitro Cultivation of the Vascular Phase of Sarcocystis capracanis and Sarcocystis tenella1
Authors: SPEER C. A. , CAWTHORN R. J. , DUBEY J. P.
Published: May 2007

ABSTRACT. Sporozoites of Sarcocystis capracanis and S. tenella (Apicomplexa) penetrated all four cell types tested (bovine monocytes, BM; bovine pulmonary artery endothelial cells, CPA; Madin‐Darby bovine kidney; and ovine monocytes). Sporozoites of S. tenella developed to meronts in BM and CPA; those of S. capracanis developed to meronts in BM only. Both species of Sarcocystis developed to large first‐generation meronts followed by small meronts. At 40 to 50 days after inoculation (DAI) of sporozoites, considerably more merozoites of S. tenella were harvested from CPA (24.9 × 106 merozoites/75‐cm2 flask; n = 4) than from BM (1.9 × 106 merozoites/75‐cm2 flask; n = 4). Merozoites of S. capracanis were most numerous in BM at 88 to 100 DAI during which time 2.1 × 106 merozoites/75‐cm2 flask (n = 4) were harvested.
Sequence of the Small Subunit Ribosomal RNA Gene Expressed in the Bloodstream Stages of Plasmodium berghei: Evolutionary Implications1
Authors: GUNDERSON J. H. , McCUTCHAN T. F. , SOGIN M. L.
Published: May 2007

ABSTRACT. We have determined the complete nucleotide sequence of the coding region of the small subunit rRNA gene expressed by bloodstream stages of the apicomplexan Plasmodium berghei. It is 2059 nucleotides long. Elements contributing to its relatively large size are all concentrated in regions known to be variable in length among eukaryotes. In a phylogenetic tree constructed from pairwise comparisons of eukaryotic small subunit rRNA sequences, the apicomplexan line branches at a rather early point in eukaryotic evolution before any multicellular kingdoms had yet appeared.
Ultrastructure and Description of a Fungus‐Feeding Amoeba, Trichamoeba mycophaga n. sp. (Amoebidae, Amoebea), from Australia1
Authors: CHAKRABORTY SUKUMAR , OLD KENNETH M.
Published: May 2007

ABSTRACT. An amoeba isolated from a wheatfield and a forest soil in Australia has been identified as Trichamoeba mycophaga n. sp. Trophozoites of this amoeba are palmate to elongate and measure 45–136 μm in length and 25–94 μm in width. Amoebae in continuous locomotion may be limax with a villous‐bulb uroid. Both the lobose pseudopodia and the advancing margin of a limax trophozoite bear an ectoplasmic crescent. The plasma membrane is coated with an electron‐dense amorphous layer ca. 100 nm thick. Endoplasm is granular with elongate to bipyramidal crystals and contains bacterial endosymbionts. Trophozoites have a single, spherical to oval nucleus, 4–10 μm in diameter, which contains a centrally located, spherical to oval nucleolus, 2.8–5.0 μm in diameter. The nucleoplasm contains aggregations of filaments distributed radially within the nuclear membrane. Cysts are 21–60 μm in diameter, with ecto‐ and endocyst walls separated by an amorphous layer.
The Ultrastructure of Spores (Protozoa: Microsporida) from Lophius americanus, the Angler Fish1
Authors: TAKVORIAN PETER M. , CALI ANN
Published: May 2007

ABSTRACT. Spinal and cranial ganglia of American angler fish, Lophius americanus, are often infected with microsporidia. This protozoon elicits the formation of large, spore‐filled, hypertrophied host cells, cysts. Previous reports of microsporidia in European lophiids identify the parasite as Spraguea lophii, a genus which has recently been shown to be dimorphic. The spores from L. americanus are monomorphic (2.8 × 1.5 μm) and uninucleate. Each spore contains a polar tube that forms six to nine coils. Spraguea lophii differs from the microsporidium described in L. americanus in several ways. Spraguea lophii has two spore types: a large spore (4.0 × 1.25 μm) containing a diplokaryon and three to four polar tube coils and a smaller uninucleate spore (3.5 × 1.5 μm) with five to six polar tube coils. Because of these major differences, the microsporidium from L. americanus is removed from the genus Spraguea and returned to its original genus, Glugea, as a new species, G. americanus n. sp. Other ultrastructural characteristics of G. americanus are included: the posterior vacuole encloses two distinct membranous structures; one is tubular and resembles a “glomerular tuft” and the second is lamellar and composed of concentric membrane whorls, additionally, the straight or manubroid portion of the polar tube proceeds beyond the posterior vacuole before it turns anteriorly and begins to coil.
Detection of Microtubules of the Flagellate Trichomonas vaginalis by Monoclonal Antibodies Specific for β‐Tubulin1
Authors: SCHWARTZMAN JOSEPH D. , KRUG EDWARD C.
Published: May 2007

ABSTRACT. Monoclonal antibodies specific for mammalian β‐tubulin recognized the microtubule cytoskeleton of the flagellated protozoon Trichomonas vaginalis. Of seven antibodies, two demonstrated the axostyle, costa, recurrent flagellum, and anterior flagella by indirect immunofluorescence microscopy. The remaining five stained a hazy reticular pattern in the cytoplasm of formaldehyde‐fixed, detergent‐extracted organisms. Western immunoblots of whole T. vaginalis extracts treated with protease inhibitors and electrophoresed on polyacrylamide gels containing sodium dodecyl sulfate showed a major band at molecular weight 50,000 when probed with only one of the antibodies which stained the axial cytoskeleton. The antibodies which stained only the cytoplasm showed a different western blot pattern with a major doublet band at MW 58,000–60,000. Another antibody, which stained both the axial cytoskeleton and the reticular cytoplasmic pattern showed major bands at MW 58,000–60,000 and also at MW 40,000–42,000. The recognition of microtubule populations in T. vaginalis by these monoclonal antibodies was different than we found earlier with Leishmania donovani and Toxoplasma gondii, where all seven antibodies recognize cytoskeletal microtubules and produce western blots characteristic of tubulin. Only one of these seven antibodies recognizes tubulin in T. vaginalis by immunoblot. The microtubules of T. vaginalis do not demonstrate all epitopes recognized by monoclonal antibodies specific for mammalian β‐tubulin; one of the antibodies appears to recognize an epitope which is morphologically associated with microtubules but does not have the characteristic MW of tubulin.