bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrastructure of Tricornia muhezae N. G., N. Sp. (Microspora, Thelohaniidae), a Parasite of Mansonia africana (Diptera: Culicidae) from Tanzania
Authors: PELL JUDITH K. , CANNING ELIZABETH U.
Published: May 2007

ABSTRACT. Collections of Mansonia africana mosquito larvae were made at one site in N.E. Tanzania in 1985 and 1987 and from two additional sites, both within about 2 mi of the original one in 1987. An octosporous microsporidian, present at all three sites, was found in both years infecting from 7 to 22% of larvae. Spores (stained in Giemsa) measured 3.0 μm × 0.25 μm × 2.25 μm × 0.26 μm. Ultrastructurally, spores were seen to have an anterior rim surrounding a depressed area where the endospore was at its thinnest. In transmission electron microscopy section, the rim appeared as two processes into which all layers of the wall extended. At the posterior end all layers of the wall extended into a simple knob‐like structure which could be interpreted as a section through a crest running longitudinally around the spore. The polar filament was anisofilar, with two anterior coils of greater diameter than the three posterior coils. Although most closely resembling the genera Amblyspora and Parathelohania in the family Thelohaniidae, the species in M. africana differs from the former, which has oval spores, broadly rounded at the ends, and from the latter, which has a prominent, ridged posterior extension to the spores. The new species has been placed in a new genus and the name Tricornia muhezae proposed.
Characterization of the Galactose‐Specific Binding Activity of a Purified Soluble Entamoeba histolytica Adherence Lectin
Authors: RAVDIN JONATHAN I. , MURPHY CHERYL F.
Published: May 2007

ABSTRACT. We studied galactose (Gal)‐specific binding of the soluble purified 260‐kDa Entamoeba histolytica adherence protein to glycosylation deficient Chinese hamster ovary (CHO) cell mutants. Our goal was to further define the lectin's functional activity and carbohydrate receptor specificity. The adherence protein was purified by acid elution from an immunoaffnity column; however, exposure of the surface membrane lectin on viable trophozoites to identical acid pH conditions had no effect on carbohydrate binding activity. Saturable Gal‐specific binding of soluble lectin to parental CHO cells was demonstrated at 4°C by radioimmunoassay; the dissociation coefficient (Kd was 2.39 × 10−8 M−1 with 5.97 × 104 lectin receptors present per CHO cell. Gal‐specific binding of lectin to Lec2 CHO cell mutants, which have increased N‐ and O‐linked terminal Gal residues on cell surface carbohydrates, was increased due to an enhanced number of receptors (2.41 × 105/cell) rather than a significantly reduced dissociation constant (4.93 × 10−8 M−1). At 4°C, there was no measurable Gal‐specific binding of the adherence protein to the Lec and IdlD.Lecl CHO mutants, which contain surface carbohydrates deficient in terminal Gal residues. Binding of lectin (20 μg/ml) to CHO cells was equivalent at 4°C and 37°C and unaltered by adding the microfilament inhibitor, Cytochalasin D (10 μg/ml). Gal‐specific binding of the lectin at 4°C was calcium independent and reduced by 81% following adsorption of only 0.2% of the lectin to CHO cells. In summary, these findings indicate that the purified E. histolytica adherence lectin demonstrates saturable Gal‐specific binding to 1–6 branched‐N‐linked and not O‐linked galactose terminal cell surface carbohydrates; however, apparently only a small percentage of purified amebic lectin molecules actually possess galactose binding activity.
Three New Species of Lagenophryid Peritrichs (Ciliophora) Ectocommensal on Freshwater Decapod Crustaceans from Madagascar1
Authors: CLAMP JOHN C.
Published: May 2007

One species of Lagenophrys and two species of Operculigera are described for the first time. Lagenophrys machaerigera n. sp. was discovered on the freshwater crab Gecarcinautes goudoti and varies between two extreme forms in the structure of its lorica aperture. Operculigera carcini n. sp. was also found on G. goudoti and exhibits several characteristics that set it apart from other members of its genus. Some of these characteristics also suggest a phylogenetic link between O. carcini and the genus Lagenophrys. Operculigera madagascarensis n. sp. was discovered on the parastacid crayfish Astacoides granulimanus. The occurrence of O. madagascarensis on a Madagascan parastacid and other species of Operculigera on Chilean parastacids suggests that parastacids are the oldest hosts of the genus Operculigera. Continental drift is the most likely mechanism by which species of Operculigera and parastacids could have been dispersed to distant parts of the southern hemisphere. The absence of Operculigera on Australian parastacids may be due to its replacement by the genus Setonophrys on those hosts.
Purification and Partial Characterization of Immobilization Antigens from Ichthyophthirius multifiliis
Authors: LIN TIAN‐LONG , DICKERSON HARRY W.
Published: May 2007

ABSTRACT Ichthyophthirius multifiliis, a parasitic ciliate of freshwater fishes, was found to have surface antigens (Ag) which elieited immobilizing antibodies (Ab) when injected into rabbits. An effort was made to purify and characterize these Ag (referred to as immobilization Ag) because of their potential role in protective immunity in fishes. Mice immunized with theront cilia were used for production of immobilizing monoclonal antibodies (MAb). Hybridomas were screened by indirect immunofluorescent light microscopy and immobilization of live parasites. Six hybridomas producing immobilizing MAb were cloned. Immobilizing MAb were used to affinity purify Ag solubilized with Triton X‐114 and Na deoxycholate. Two membrane protein Ag of approximately 48 and 60 kDa were identified. Immobilizing MAb failed to react with these Ag on Western blots and, conversely, MAb that reacted with the Ag on Western blots did not immobilize live organisms. These results suggest that immobilization required native conformational epitopes which were altered by Western blotting procedures. Individual MAb reactive on Western blots recognized both the 48‐ and 60‐kDa proteins indicating the presence of common epitopes. Affinity purified Ag elicited immobilizing antisera when injected into rabbits, mice, and channel catfish.
Action Spectra for Step‐Up Photophobic Response in Blepharisma
Authors: MATSUOKA TATSUOMI , MATSUOKA SETSUKO , YAMAOKA YUMIKO , KURIU TOSHIHIKO , WATANABE YOSHIYA , TAKAYANAGI MIYUKI , KATO YOJI , TANEDA KOJI
Published: May 2007

ABSTRACT The cells of Blepharisma which possess red pigment (blepharismin) show step‐up photophobic response (temporal ciliary reversal induced by a sudden increase in light intensity). Bleaching of the cells by cold shock raised a threshold light intensity for the response, Oxidation of red pigment that produced blue pigment did not raise the threshold for the response. The action spectrum for the step‐up photophobic response of the cells which possess normal red pigment had peaks at about 580, 540 and 490 nm, a value which coincided with peaks of an absorption spectrum of the red pigment. The absorption spectrum of oxidized pigment (blue pigment) shifted 20 nm toward infrared light. The action spectrum for the response of the cells which possess blue pigment also shifted 20 nm toward infrared light. Results suggest that red pigment might be involved in the step‐up photophobic response. Key words. Blepharismin, ciliary reversal, photoreceptors, photoresponse.
The Immobilization Antigens of Tetrahymena thermophila Are Glycoproteins
Authors: RON ARIE , WILLIAMS NORMAN E. , DOERDER F. PAUL
Published: May 2007

ABSTRACT The four immobilization antigens controlled by the SerH locus in Tetrahymena thermophila have been isolated and partially characterized (Doerder, F. P. & Berkowitz, M. S. 1986. Purification and partial characterization of the H immobilization antigens of Tetrahymena thermophila. J. Protozool., 33:204–208). We show here, using immunoprecipitation and electrophoresis after labeling with 35S‐methionine, 14C‐mannose, 14C‐glucosamine, and N‐Acetyl‐d‐[1‐3H]glucosamine, that these proteins are glycosylated. We suggest the immobilization antigens in Tetrahymena may be anchored to the surface membrane by phosphatidylinositol glycans.
Ultrastructure of Gametogenesis and Sporogony of Haemogregarina (sensu lato) myoxocephali (Apicomplexa: Adeleina) in the Marine Leech Malmiana scorpii
Authors: SIDDALL MARK E. , DESSER SHERWIN S.
Published: May 2007

ABSTRACT The sexual and sporogonic development of Haemogregarina (sensu lato) myoxocephali, an apicomplexan blood parasite of longhorn sculpin, Myoxocephalus octodecemspinosus, was studied by transmission electron microscopy. All stages of development were observed epicellularly within intestinal epithelial cells of the leech Malmiana scorpii. During microgametogenesis nuclear division was characterized by a transnuclear cytoplasmic channel containing the spindle microtubules. Four aflagellate microgametes were formed. During fertilization, a single microgamete nucleus was associated with the endoplasmic reticulum in the macrogamete, followed by fusion of the nuclear envelopes of the gametes. Sporogony involved peripheral budding of sporozoite anlagen and subsequent development to form approximately 32 sporozoites in mature oocysts.
Acanthamoeba healyi N. Sp. and the Isoenzyme and Immunoblot Profiles of Acanthamoeba spp., Groups 1 and 3
Authors: MOURA HERCULES , WALLACE SARA , VISVESVARA GOVINDA S.
Published: May 2007

ABSTRACT Two strains of Acanthamoeba isolated from human brain tissue and a strain of Acanthamoeba isolated from a fish were compared with 10 species of Acanthamoeba belonging to groups 1, 2 and 3 based on their isoenzyme profiles and antigenic characteristics. A total of 12 enzymes were studied. The isoenzymes and antigens were electrophoretically separated on polyacrylamide gradient gels, and the patterns obtained were compared after appropriate staining for particular enzymes and reactivities with homologous and heterologous rabbit anti‐Acanthamoeba antisera. One of the human strains (CDC:1283:V013) was identified as A. healyi n. sp. because of its unique isoenzyme profiles for 11 of the 12 enzymes tested. The other human isolate was reidentified as A. culbertsoni because its isoenzyme profiles for 10 of 12 enzymes resembled those of A. culbertsoni, Lilly A‐1 strain. Since the isoenzyme profiles and the antigenic patterns of the fish isolate as well were remarkably similar to those of A. royreba, it was considered as a strain of A. royreba. Polyacrylamide gradient gel electrophoresis appears to be a powerful technique for the study of isoenzymes and antigens of Acanthamoeba.
A Comparative Analysis of the Morphology of Holosticha corlissi N. Sp. (Ciliophora, Hypotrichida) and Related Species1
Authors: FERNANDEZ‐GALIANO DIMAS , CALVO PILAR
Published: May 2007

ABSTRACT The morphology of the hypotrichous ciliate, Holosticha corlissi n. sp., found in the moss Calliergonella cuspidata taken from the beech wood of Montejo de la Sierra (Madrid, Spain) is described. Some characteristics (organization of the mid‐ventral, frontal and fronto‐terminal cirri, presence of a buccal cirrus and the number of transverse cirri) are sufficiently different from the closely related species H. intermedia, H. sigmoidea and H. xanthichroma to suggest that it is a separate species, although its body shape, nucleus and buccal apparatus are very similar.
Continuous Cultivation and Drug Susceptibility Testing of Plasmodium falciparum in a Malaria Endemic Area
Authors: ODUOLA AYOADE M. J. , OGUNDAHUNSI OLUMIDE A. T. , SALAKO LATEEF A.
Published: May 2007

ABSTRACT Isolates (UCH‐23 and OM) and cloned strains of Plasmodium falciparum (Clones W‐2 and D‐6) were maintained in continuous culture for 28 to 150 days using culture media supplemented with 10% (v/v) heat inactivated semi‐immune human plasma. Microscopic appearance and growth rates (R) of the parasites in media supplemented with semi‐immune human plasma [R = 1.13 (W‐2), 0.92 (D‐6), 0.75 (OM) and 0.84 (UCH‐23)] were comparable to those of parallel cultures maintained in media supplemented with 10% (v/v) heat inactivated non‐immune human plasma [R = 1.42 (W‐2), 0.83 (D‐6), 0.66 (OM) and 0.89 (UCH‐23)]. In addition, IC50 for chloroquine and mefloquine against the two cloned strains of P. falciparum maintained in culture media supplemented with either non‐immune human plasma or semi‐immune human plasma were identical. Although growth rates of new isolates (UCH‐23 and OM) fluctuated over time, they stabilized between the 12th and 19th day of adaptation to culture. This fluctuation in growth rates of the new isolates underscores the influence of population dynamics during adaptation of P. falciparum to continuous culture. Sixty‐eight percent of the primary isolates (170 of 250) obtained from patients in Ibadan were successfully adapted and maintained in continuous culture using semi‐immune human plasma. The results of these studies indicate that semi‐immune human plasma is a suitable supplement for continuous cultivation and drug susceptibility testing of P. falciparum. This finding will have practical implications in malaria endemic areas where difficulties in obtaining non‐immune human plasma or serum limits establishment of continuous culture of P. falciparum and its application in studies on malaria.
Exceptions to Mutual Exclusion Among Cell Surface i‐Antigens of Tetrahymena thermophila During Salt Stress and Stationary Phase
Authors: SMITH DEBORAH L. , DOERDER F. PAUL
Published: May 2007

ABSTRACT In ciliates, only one of the alternative forms of the immunodominant membrane glycoprotein usually coats the external surface of the cell. Such mutual exclusion is regulated at the pretranslational level by mechanisms that result in the expression of a single protein gene. In the holotrich Tetrahymena thermophila five alternative cell surface immobilization proteins (i‐antigens) are expressed under different conditions of temperature (L, H, T) and culture media (I, S). Using polyclonal and monoclonal antibodies to these proteins and a cDNA probe derived from the SerH3 gene, we have reinvestigated expression of i‐antigens in media supplemented with 0.2 M NaCl. We find that in addition to S, the H and L antigens are also present on the cell surface. While all three i‐antigens may be simultaneously present on the cell surface, the combinations S/L and S/H are more frequent. Compared to cells expressing H and L singly, the level of H3 mRNA is diminished, and a subset of the L family of polypeptides is variably expressed. The expression of S begins within 30 min after transfer to NaCl‐supplemented medium, while the expression of L begins three days to several weeks after transfer. When cells are transferred out of NaCl‐supplemented medium, S is turned off within 24 h, and L is expressed for at least 1 wk prior to the return of full H expression. Although these differences in kinetics suggest differences in control mechanism(s), the absence of I and T on the surface of NaCl‐grown cells suggests that there is also a common regulatory link among H, S and L. We also find that S is coexpressed with H in stationary phase cells grown in non‐NaCl supplemented peptone medium. Such growth cycle dependent expression is consistent with the rapid switch in S expression upon media shift and occurs at all temperatures. A model to explain these results is presented.
A Fossil Myxomycete Plasmodium from Eocene‐Oligocene Amber of the Dominican Republic
Authors: WAGGONER BENJAMIN M. , POINAR GEORGE O.
Published: May 2007

ABSTRACT The first known fossil slime mold with part of the plasmodium preserved, from Eocene‐Oligocene amber of the northern Dominican Republic, is described here. We assign it to the myxomycetes on the basis of its cytoplasmic structure. The paleoecological and evolutionary importance of this fossil is briefly discussed.
Codon Usage in Giardia lamblia
Authors: CHAR SHOBHA , FARTHING MICHAEL J. G.
Published: May 2007

ABSTRACT A codon usage table for the intestinal parasite Giardia lamblia was generated by analysis of the nucleotide sequences of eight genes comprising 3,135 codons. Codon usage revealed a biased use of synonomous codons with a preference for NNC codons (42.1%). The codon usage of G. lamblia more closely resembles that of the prokaryote Halobacterium halobium (correlation coefficient r= 0.73) rather than that of other eukaryotic protozoans, i.e. Trypanosoma brucei (r= 0.434) and Plasmodium falciparum (r=–0.31). These observations are consistent with the view that G. lamblia represents the first line of descent from the ancestral cells that first took on eukaryotic features.
Inhibition of the Spore Polar Filament Extrusion of the Microsporidium, Encephalitozoon hellem, Isolated from an AIDS Patient1
Authors: LEITCH GORDON J. , HE QING , WALLACE SARA , VISVESVARA GOVINDA S.
Published: May 2007

Spores of the microsporidian parasitic protozoan Encephalitozoon hellem were purified and incubated at 37° C in a solution with an electrolyte composition similar to that of mammalian extracellular fluid, and in solution in which the calcium had been replaced with 0.2 mM EGTA. Polar filament extrusion (germination) was monitored by both scanning electron microscopy and light microscopy. Germination was pH‐dependent, with optima at pH 7.4 and 9.5, and was significantly greater in the presence of medium calcium. Hydrogen peroxide caused a concentration‐dependent increase in germination that was also reduced in a calcium‐free medium. Four agents were found to inhibit spontaneous and H2O2‐stimulated polar filament extrusion: the microfilament disrupter, cytochalasin D; the microtubule disrupter, demecolcine; the calcium channel blocker, nifedipine; and the antifungal agent, itraconazole. These results are consistent with the existence of a calcium‐channel‐mediated step, and requirements for an F‐actin‐ and for a tubulin‐containing element in the germination process of the spore of this parasite. Nifedipine, cytochalasin D and itraconazole all have different sites of action and were therefore able to potentiate one another when used in paired combination to inhibit germination.
Acanthamoeba stevensoni N. Sp. (Protozoa: Amoebida) from Sewage‐Contaminated Shellfish Beds in Raritan Bay, New York
Authors: SAWYER THOMAS K. , NERAD THOMAS A. , LEWIS EARL J. , McLAUGHLIN SHAWN M.
Published: May 2007

Marine sediments from 12 shallow water stations in Raritan Bay, New York were tested for the presence of Acanthamoeba. Eight stations were positive for one or more species of Acanthamoeba, A. castellanii, A. comandoni, A. hatchetti, A. lenticulata, A. polyphaga, A. rhysodes, and Acanthamoeba spp. Isolates that grew at 38–40° C were found at four stations (A. comandoni, A. lenticulata, and two unidentified strains). The two unknown strains were characterized on the basis of morphological features, isoenzyme profiles, and mouse pathogenicity tests. One of the two strains was determined to be a new species and is designated herein as Acanthamoeba stevensoni n. sp., ATCC 50388. Mature cysts were most similar to those of morphological Group II of Pussard & Pons (1977). Acanthamoeba stevensoni n. sp. was isolated from inshore coastal sediments where seawater ranged from 20–30%‰ (ppt.). The sediments supported commercially valuable populations of hard clams, Mercenaria mercenaria, that required depuration prior to sale because of contamination by sewage‐associated bacteria.
Development ofTrypanosoma (M.) theileriin Tabanids
Authors: BÖSE REINHARD , HEISTER NICOLIN C.
Published: May 2007

Thus far the life cycle ofTrypanosoma (Megatrypanum) theilerihas not been studied. We collected tabanids during the mass hatching, when only few tabanids are infected with trypanosomes. Tabanids were caught immediately after attacking a bait cow to serve as controls or after they had been allowed to engorge on theTrypanosoma (M.) theileri‐infected cow. Tabanids were kept in the laboratory and used to study the developmental cycle ofT. (M.) theileriin the tabanid gut. From day 1 to day 10 the presumably unfed controls and the engorged tabanids were dissected and cytological smears made from the mid‐ and hindgut. In total 2.6% (1/38) of the controls and 39% (23/59) of the engorged tabanids were positive for trypanosomes in the 1991 season. From day 1 to day 4 after engorgement trypanosomes were found in the midgut. Epimastigotes with a length of 29 μm on day 1 after infection multiplied by inequal division to form smaller epimastigotes of 26 μm on day 3. On day 4 morphologically indistinguishable trypanosomes of 21 μm total length were found in both mid‐ and hindgut. From day 5 to day 10 trypanosomes were found only in the hindgut in which the transformation to metacyclics was demonstrated, i.e. epimastigotes transformed to amastigote stages of 5 μm in total length.
Serotypic Variation Among Isolates of Ichthyophthirius multifiliis Based on Immobilization
Authors: DICKERSON HARRY W. , CLARK THEODORE G. , LEFF ADAM A.
Published: May 2007

Efforts have been made to determine whether surface antigens could be used as biochemical markers to define strain differences in the parasitic ciliate Ichthyophthirius multifiliis. In previous studies, a wild‐type isolate designated G1 was found to have surface proteins analogous to the immobilization antigens of Paramecium and Tetrahymena; rabbit antiserum against this strain immobilizes homologous cells in vitro. It has now been shown for two additional Ichthyophthirius isolates (designated G1.1 and G2) that immobilization antigens are both present and serologically distinct. Proteins of similar size, which cross‐react in Western blots with rabbit antisera against immobilization antigens of the G1 strain, are nevertheless found in the G1.1 and G2 isolates. As shown by Southern blotting analysis, the G1.1 and G2 strains also contain genomic DNA sequences which hybridize with an immobilization antigen cDNA from G1 when probed under conditions of reduced stringency. The serotypic differences in immobilization between I. multifiliis isolates appear to be stable over time and provide a means of discriminating strains. In addition to providing a basis for comparative studies, the work described here has implications for the development of vaccines against this important fish parasite.
Pyrimidine Salvage Pathways In Toxoplasma Gondii
Authors: ILTZSCH MAX H.
Published: May 2007

ABSTRACT. Pyrimidine salvage enzyme activities in cell‐free extracts of Toxoplasma gondii were assayed in order to determine which of these enzyme activities are present in these parasites. Enzyme activities that were detected included phosphoribosyltransferase activity towards uracil (but not cytosine or thymine), nucleoside phosphorylase activity towards uridine, deoxyuridine and thymidine (but not cytidine or deoxycytidine), deaminase activity towards cytidine and deoxycytidine (but not cytosine, cytidine 5′‐monophosphate or deoxycytidine 5′‐monophosphate), and nucleoside 5′‐monophosphate phosphohydrolase activity towards all nucleotides tested. No nucleoside kinase or phosphotransferase activity was detected, indicating that T. gondii lack the ability to directly phosphorylate nucleosides. Toxoplasma gondii appear to have a single non‐specific uridine phosphorylase enzyme which can catalyze the reversible phosphorolysis of uridine, deoxyuridine and thymidine, and a single cytidine deaminase activity which can deaminate both cytidine and deoxycytidine. These results indicate that pyrimidine salvage in T. gondii probably occurs via the following reactions: cytidine and deoxycytidine are deaminated by cytidine deaminase to uridine and deoxyuridine, respectively; uridine and deoxyuridine are cleaved to uracil by uridine phosphorylase; and uracil is metabolized to uridine 5′‐monophosphate by uracil phosphoribosyltransferase. Thus, uridine 5′‐monophosphate is the end‐product of both de novo pyrimidine biosynthesis and pyrimidine salvage in T. gondii.
Septata Intestinalis N. G., N. Sp., an Intestinal Microsporidian Associated With Chronic Diarrhea and Dissemination In Aids Patients
Authors: CALI ANN , KOTLER DONALD P. , ORENSTEIN JAN M.
Published: May 2007

ABSTRACT. Intestinal microsporidiosis in patients diagnosed with acquired immunodeficiency syndrome (AIDS) and having chronic diarrhea was first reported in 1985 and the associated microsporidian was named Enterocytozoon bieneusi. the intracellular developmental cycle of E. bieneusi in enterocytes has been demonstrated and many cases have been reported worldwide. This report presents the life cycle of a second intestinal microsporidian, associated with the same symptoms, in five AIDS patients. This new microsporidian also infects enterocytes but its pathology and morphology differ from that of E. bieneusi. It involves lamina propria macrophages, fibroblasts, and endothelial cells and can disseminate to infect other parts of the body, e.g. the kidney and gall bladder. the parasite cycle includes development of rounded uninucleate and elongated bi‐ or tetranucleate cells without the formation of plasmodial stages. Sporogony is similar to the more typical development of microsporidia with sporoblast morphogenesis occurring after the last cell division. the development of cells within chambers of a septate, honeycomb‐like, parasite‐secreted fibrillar network and surrounded by a parasitophorous vacuole, however, is unique to this microsporidian, justifying the establishment of a new genus and species, Septata intestinalis n. g., n. sp.
Structure, Bioadhesive Distribution and Elastic Properties of the Agglutinated Test of Astrammina rara (Protozoa: Foraminiferida)
Authors: BOWSER SAMUEL S. , BERNHARD JOAN M.
Published: May 2007

ABSTRACT. The fine structure, elastic properties, and distribution of the fibrous, meshlike cement (bioadhesive) were studied for the test of the antarctic agglutinated foraminiferan Astrammina rara. Grain‐size analysis of particles incorporated into the test compared with adjacent sediment indicates that A. rara is grain‐size selective. Fractured tests curl inward, suggesting that the test is under tension—an impression substantiated by micromanipulation observations. Changes in test appearance were examined by scanning electron microscopy after sequential chemical treatments combined with ultrasonication. Organic fibrils securing fine‐grained particulates on the test exterior were removed during initial sonication. A veil of fibrous organic material lining the test interior (i.e. inner organic lining) was removed by treatment with a nonionic detergent, revealing ligamentous cables of bioadhesive securely joining large grains. These cables are partially disrupted by treatment with sodium dodecyl sulfate, and further disrupted by disulfide reducing agents, suggesting that protein is an integral adhesive component. The large detrital grains incorporated into the test are arranged in an interlocked, optimally packed fashion. Together, these observations indicate that the seemingly simple spherical architecture of A. rara's test is in fact quite complex, consisting of large grains compressed by tensile cables of a proteinaceous bioadhesive, with additional rigidity supplied by fine particulate “mortar” deposited externally.
A Group I Intron in the SSUrDNA of Some Naegleria spp. Demonstrated by Polymerase Chain Reaction Amplification
Authors: JONCKHEERE JOHAN F. DE
Published: May 2007

ABSTRACT. The small subunit ribosomal DNA (SSUrDNA) of all described Naegleria spp. was amplified by polymerase chain reaction with universal primers. In all strains of N. andersoni andersoni, N. andersoni jamiesoni, N. australiensis italica and two related strains, and one out of four clusters of N. gruberi, a band of approximately 3.3 kb was obtained. All other strains displayed a band with the expected DNA length of 2.0 kb. This means the former have a 1.3 kb intron in the SSUrDNA. Restriction analysis demonstrated that the intron is between two conserved Pst I sites at the 5′ end of the SSUrDNA It also suggested the introns might not be identical in each species or subspecies. The Pst I fragment of SSUrDNA containing the 1.3 kb insert in N. andersoni andersoni was cloned and sequence. The 1,296‐nucleotide insert is situated in helix 19 of the SSUrDNA, which is an area of conserved primary and secondary structure. Sequence and secondary structure analyses of the insert revealed it is a group I intron. This group I intron is very large and contains an open reading frame that could serve to encode a polypeptide of 139 amino acids in size.
The Challenge of Pneumocystis carinii Culture1
Authors: SLOAND ELAINE , LAUGHON BARBARA , ARMSTRONG MARTINE , BARTLETT MARILYN S. , BLUMENFELD WALTER , CUSHION MELANIE , KALICA ANTHONY , KOVACS JOSEPH A. , MARTIN WILLIAM , PITT ELISABETH , PESANTI EDWARD L. , RICHARDS FRANK , ROSE RICHARD , WALZER PETER
Published: May 2007

ABSTRACT. Published and unpublished data on the cultivation of P. carinii were reviewed by a panel of investigators convened by the National Institutes of Health. Although several cell culture systems allow propagation of P. carinii for a limited time with modest rates of replication, these have not proved adequate for isolation of P. carinii in sufficient quantity to explore important basic biological investigation. Attempts at cell‐free culture have yielded only transient proliferation. Because much of the unsuccessful work on cultivation of the organism has been unpublished, the panel agreed that these data may be useful to other investigators in designing experimental strategies for cultivation. Therefore, the purpose of this report is to make available this information to researchers, lest others unknowingly repeat unsuccessful methods. It is hoped that by documenting the history and the complexities of Pneumocystis culture, renewed interest and efforts will be directed toward this fundamental scientific challenge.
Nitrogen Metabolizing Enzyme Activities In the Free‐Living Soil Amoebae Acanthamoeba Castellanii, Acanthamoeba Polyphaga and Hartmannella Vermiformis
Authors: WEEKERS PETER H. H. , DRIFT CHRIS VAN DER
Published: May 2007

ABSTRACT. Free‐living soil amoebae consume a wide variety of food, including algae, yeast, small protozoa and especially bacteria, which they digest to fulfil their nutritional requirements. Amoebae play an active role in the nitrogen mineralization in soils due to their nitrogen metabolizing capacities. However, little is known about nitrogen metabolizing enzyme activities in these free‐living soil amoebae. In this study a number of key enzymes involved in the nitrogen metabolism of the axeaically cultivated free‐living soil amoebae Acanthamoeba castellanii, Acanthamoeba polyphaga and two different strains of Hartmannella vermiformis were determined. the specific enzyme activities for exponential growth phase ceils were calculated and it appeared that the species tested possessed urate oxidase, glutamine synthetase, NADH‐dependent glutamate dehydrogenase, glutamate oxaloacetate transaminase and glutamate pyruvate transaminase activity. Glutamate synthase activity could not be detected in any of these species. the levels of specific activities varied depending on the enzymes tested. For all species the highest activities were detected for the transaminase reactions yielding glutamate, and for glutamate dehydrogenase. A general conclusion is that the pathway of nitrogen assimilation in free‐living soil amoebae is similar to the one observed for other eukaryotes. Differences in specific activities were detected between the species.
Novel Structure In the Pellicular Complex of Plasmodium Falciparum Gametocytes1
Authors: KAIDOH TOSHIYUI , NATH JAYASREE , OKOYE VINCENT , AIKAWA MASAMICHI
Published: May 2007

ABSTRACT. Using transmission electron microscopy, transverse dense bands were found to be associated with subpellicular microtubules and inner membraner in Plasmodium falciparum gametocytes. These dense bands may act as supportive structures to maintain the parallel arrangement of the microtubules, and/or to connect them to the inner membranes.
In Vitro Propagation of the Protozoan Perkinsus Marinus, A Pathogen of the Eastern Oyster, Crassostrea Virginica
Authors: PEYRE JEROME F. LA , FAISAL MOHAMED , BURRESON EUGENE M.
Published: May 2007

ABSTRACT. Perkinsus marinus, a pathogen of eastern oysters (Crassostrea virginica), has been successfully propagated in vitro. Cultures of the parasite were initiated from heart fragments of an infected oyster. the cultured protozoan (designated Parkinsus‐1) was similar in morphology at both the light and transmission electron microscopy levels to histozoic stages of P. marinus in naturally infected oysters. In addition, cultured cells incubated in fluid thioglycollate medium produced enlarged cells (prezoosporangia) that stained blue‐black in Lugol's solution, a response characteristic to Perkinsus spp. and used in routine diagnosis. Polyclonal antibodies raised against P. marinus prezoosporangia reacted positively to Perkinsus‐1. Finally, the cultured cells infected susceptible oysters and reisolation of Perkinsus‐1 cells was possible from the hearts of experimentally infected oysters. the culture medium contained most of the known constituents of cell‐free hemolymph of oysters. the success achieved in culturing P. marinus will allow further investigations aimed at reducing mortalities caused by this important oyster pathogen and at addressing many unanswered questions about its biology and pathobiology.
Evaluation of Rhodamine 123 As A Probe For Monitoring Mitochondrial Function In Trypanosoma Brucei Spp.
Authors: DIVO ALAN A. , PATTON CURTIS L. , SARTORELLI ALAN C.
Published: May 2007

ABSTRACT. Rhodamine 123, a membrane potential‐specific dye, has been evaluated as a probe to monitor the function of the mitochondrion in long slender bloodstream and procyclic trypomastigotes of several Trypanosoma brucei spp. By epifluorescence microscopy, mitochondrial development has been followed in long slender bloodstream and procyclic organisms stained with rhodamine 123. to photograph stained long slender bloodstream forms, it was necessary to develop a method to completely immobilize viable organisms. In both parasite forms, as the cell cycle progressed, the mitochondrion developed from a thread‐like structure to a highly branched organelle. A dramatic reorganization occurred preceding cytokinesis to produce two progeny thread‐like structures which were partitioned into newly formed daughter cells. the organelle within the long slender trypomastigote was found to stain optimally at 0.3 μ/ml of rhodamine 123, while the procyclic form required 3.0 μ/ml. the results suggest that the plasma membrane potential is higher in the long slender parasite than in the procyclic form. the effects of inhibitors that disrupt mitochondrial function were examined in long slender and procyclic parasites, and some of these agents were shown to affect rhodamine 123 accumulation and retention. In long slender trypomastigotes the trypanosome alternative oxidase does not appear to be coupled to proton pumping, whereas in procyclic organisms the effects of inhibitors indicate that this oxidase may be coupled to a pathway that is branched preceding an antimycin A1‐sensitive site.
Oral Morphogenesis of the Microstome to Macrostome Transformation in Miamiensis avidus Strain Ma/21
Authors: GÓMEZ‐SALADIN EDUARDO , SMALL EUGENE B.
Published: May 2007

ABSTRACT. Miamiensis avidus, a marine scuticociliate, undergoes microstome to macrostome transformation. This process is induced by prey ciliates. the morphogenesis of this process was examined using scanning electron microscopy and light microscopy of quantitative protargol‐stained specimens. Several stages are identified and described.
Ultrastructure of Mitosis and Cytokinesis In the Colorless Flagellate Katablepharis Ovalis Skuja
Authors: LEE ROBERT EDWARD , MILLER‐HUGHES CYNTHIA , KUGRENS PAUL
Published: May 2007

ABSTRACT. Mitosis and cytokinesis in Katablepharis ovalis, a colorless flagellate, was investigated. Two new flagella are produced prior to prophase, resulting in a motile quadriflagellate cell during mitosis. the inner array of microtubules of the feeding apparatus disappears before prophase begins. the nuclear envelope disperses during prophase, apparently being converted into rough endoplasmic reticulum. the chromatin condenses and the nucleolus disperses with spindle microtubules appearing oriented perpendicular to the longitudinal axis of the cell. At metaphase, the chromatin is condensed as a single disc‐shaped mass and rough endoplasmic reticulum flanks the chromatin mass on each side. Groups of spindle microtubules pass through tunnels in the rough endoplasmic reticulum and through electron‐translucent areas of the chromatin. the spindle microtubules end at a number of minipoles in the cytoplasm. Vesicles, ribosomes, mitochondria and endoplasmic reticulum migrate among the spindle microtubules. There is no polar body or any electrondense area associated with the spindle poles. the basal bodies of the flagella remain attached to the axonemes and do not participate in mitosis. In anaphase, the chromatin separates and migrates to the poles. During telophase, the nuclear envelope reforms from the rough endoplasmic reticulum and the nucleoli reappear. the spindle microtubules are persistent during telophase. Cytokinesis occurs by longitudinal fission, starting at the anterior end and progressing posteriorly. Cytokinesis may be driven by elongation of the spindle microtubules since there is no visible structure associated with the furrowing.
Revision of the Family Spironemidae Doflein (Protista, Hemimastigophora), With Description of Two New Species, Spironema Terricola N. Sp. and Stereonema Geiseri N, G., N. Sp.
Authors: FOISSNER ILSE , FOISSNER WILHELM
Published: May 2007

ABSTRACT. Two new hemimastigophoran flagellates are described using light and electron microscopy, and the family Spironemidae is revised. Spironema terricola n. sp. occurs in soil from the Grand Canyon (southwest USA). It moves in a conspicuously euglenoid manner and differs from S. multiciliatum Klebs by its vermiform shape and shorter kinetics. Spironema terricola is similar to Goodey's Spironema multiciliatum from soil in England. However, Goodey's vermiform species has a very elongate nucleus and is thus neither identical with S. terricola, which has a roundish nucleus, nor with Klebs' lanceolate S. multiciliatum; we consider it a new species, Spironema goodeyi n. sp, Stereonema geiseri n. g., n. sp. was discovered in the Aufwuchs (periphyton) of a river in Bavaria, Germany. the new genus differs from Spironema by its a contractility, and from Hemimastix by its shorter kinetics and less plicate cortex. the fine structure of Spironema and Stereonema is very similar to that of Hemimastix Foissner et al., viz., the cortex is composed of two plates having diagonal symmetry and the flagellated basal bodies have associated a short and a long microtubular ribbon. All species have unique extrusomes of the same type. the main differences between the three genera and five species recognized are contractility, length of kinetics, body size, shape of cell and nucleus, and particulars of the cortex and extrusomes. the phylogenetic relationships of the Hemimastigophora are still uncertain. However, the diagonal symmetry of the cortical plates and the pronounced euglenoid movement of Spironema spp. suggest a common ancestor with euglenids.
Orientation of Paramecium Under the Conditions of Weightlessness
Authors: HEMMERSBACH‐KRAUSE RUTH , BRIEGLEB WOLFGANG , HÄDER DONAT‐P. , VOGEL KURT , GROTHE DIETER , MEYER IRMIN
Published: May 2007

ABSTRACT. A cell culture of Paramecium with a precise negative gravitaxis was exposed to 4 times 10‐6g during a parabolic flight of a sounding rocket for 6 min. Computer image analysis revealed that without gravity stimulus the individual swimming paths remained straight. In addition, three reactions could be distinguished. For about 30 s, paramecia maintained the swimming direction they had before onset of low gravity. During the next 20 s, an approximate reversal of the swimming direction occurred. This period was followed by the expected random swimming pattern. Similar behavior was observed under the condition of simulated weightlessness on a fast‐rotating clinostat. Control experiments on the ground under hyper‐gravity on a low‐speed centrifuge microscope and on a vibration test facility proved that the observed effects were caused exclusively by the reduction of gravity.
Balamuthia Mandrillaris, N. G., N. Sp., Agent of Amebic Meningoencephalitis In Humans and Other Animals
Authors: VISVESVARA GOVINDA S. , SCHUSTER FREDERICK L. , MARTINEZ A. JULIO
Published: May 2007

ABSTRACT. We recently reported the isolation of a leptomyxid ameba from the brain of a mandrill baboon that died of meningo‐encephalitis. Based on light and electron microscopic studies, animal pathogenicity tests, and immunofluorescence patterns, we conclude that our isolate differs fundamentally from the other two amebas (Leptomyxa and Gephyramoeba) included in the Order Leptomyxida. We therefore created a new genus, Balamuthia, to accommodate our isolate and described it as Balamuthia mandrillaris to reflect the origin of the type species. Briefly, B. mandrillaris is a pathogenic ameba that causes amebic encephalitis in humans and animals. It has trophic and cyst stages in its life cycle, and is uninucleate with a large vesicular nucleus and a central nucleolus. Mature cysts have a tripartite wall consisting of an outer loose ectocyst, an inner endocyst and a middle mesocyst. Unlike Acanthamoeba and Naegleria, the other two amebas that cause amebic encephalitis in humans, Balamuthia will not grow on agar plates seeded with enteric bacteria. However, Balamuthia grows on a variety of mammalian cell cultures and kills mice following intranasal or intraperitoneal inoculation. Based on immunofluorescence testing, 35 cases of amebic encephalitis in humans and three in other animals have been identified worldwide as being caused by Balamuthia.
Processing and Secretion of Lysosomal Acid α‐Glucosidase In Tetrahymena Wild Type and Secretion‐Deficient Mutant Cells
Authors: BANNO YOSHIKO , OKANO YUKIO , FURUKAWA KIYOSHI , TIEDTKE ARNO , KOBATA AKIRA , NOZAWA YOSHINORI
Published: May 2007

ABSTRACT. The proteolytic processing and secretion of a lysosomal enzyme, acid α‐glucosidase, was studied by pulse‐chase labeling with [35S]methionine in Tetrahymena thermophila CU‐399 cells treated with ammonium chloride. This cell secreted a large amount of acid α‐glucosidase into the cultured medium during starvation. the secretion was found to be repressed by addition of ammonium chloride (NH4Cl). Acid α‐glucosidase was produced as a precursor form (108 kDa) and then processed to a mature polypeptide (105 kDa) within 60 min. This mature enzyme was secreted into the media within 2‐3 h after chase, whereas the precursor form was not secreted by either control cells or NH4Cl‐treated cells. NH4Cl did not affect the processing of the precursor acid α‐glucosidase. Processing profile of this enzyme was apparently indistinguishable from that of the mutant MS‐1 defective in lysosomal enzyme secretion. Furthermore, the purified extracellular (CU‐399) and intracellular (MS‐1) acid a‐glucosidases were the same in molecular mass (105 kDa) and enzymatic properties. They contained no mannose 6‐phosphate residues in N‐linked oligosaccharides. These results suggested that unlike mammalian cells, Tetrahymena acid α‐glucosidase may be transferred to lysosomes by a mannose 6‐phosphate receptor‐independent mechanism, and also that low pH was not essential for the proteolytic processing of precursor polypeptide.
Naegleria: A Research Partner For Cell and Developmental Biology1
Authors: FULTON CHANDLER
Published: May 2007

ABSTRACT. Organisms in the genus Naegleria offer special opportunities for research in contemporary biology. the dramatic cell differentiation from amebae to flagellates is unique among eukaryotes in the rapidity, synchrony, reproducibility, homogeneity, and accessibility of a major phenotypic change. Environmental signals initiate a progressive signal transduction pathway in which genes are turned on, including those for several calcium‐binding proteins, and newly synthesized proteins become localized in newly assembled organelles, including the centriole‐like basal bodies, with the overall consequence that the cell changes its shape, motility, and behavior. This essay reviews research opportunities for which Naegleria excels, as well as interesting aspects of its biology that provide challenges for future investigations. Because these organisms alternate between two major eukaryotic motility forms, their phylogenetic position is also provocative. Although there are hints that Naegleria is capable of sexual reproduction in nature, mating has not yet been observed in the laboratory. In order to fully exploit the opportunities offered by this wonderful experimental system we are working to develop means to do genetic manipulation, in particular via DNA‐mediated transformation.
An Ultrastructural Study of Lentomonas applanatum (Preisig) N. G. (Euglenida)
Authors: FARMER MARK A. , TRIEMER RICHARD E.
Published: May 2007

ABSTRACT. Lentomonas applanatum (syn. Entosiphon applanatum Preisig) is a biflagellate, phagotrophic euglenid found in intertidal salt marshes. Lentomonas applanatum bears a superficial similarity to Entosiphon sulcatum, however, an ultrastructural study of L. applanatum revealed many features that are atypical for other described species of the genus Entosiphon. These features include number and organization of pellicular strips, construction of the feeding apparatus, nature of the flagellar transition zone and flagellar apparatus, and point of flagellar emergence. These differences show that L. applanatum is related more closely to phagotrophic genera such as Ploeotia than to E. sulcatum. The construction of the feeding apparatus and pellicle suggest that L. applanatum has retained many of the pleisiomorphic characters that were present in the earliest euglenids. The presence of similar structures in other related protists may provide important clues as to the evolution of the Euglenida.
Aminopeptidases from Plasmodium falciparum, Plasmodium chabaudi chabaudi and Plasmodium berghei
Authors: CURLEY G. PAUL , O'DONOVAN SUSAN M. , MCNALLY JOHN , MULLALLY MARGARET , O'HARA HELEN , TROY ALICE , O'CALLAGHAN SUE‐ANN , DALTON JOHN P.
Published: May 2007

ABSTRACT. Using fluorogenic substrates and polyacrylamide gels we detected in cell‐free extracts of Plasmodium falciparum, Plasmodium chabaudi chabaudi and Plasmodium berghei only a single aminopeptidase. A comparative study of the aminopeptidase activity in each extract revealed that the enzymes have similar specificities and kinetics, a near‐neutral pH optima of 7.2 and are moderately thermophilic. Each has an apparent molecular weight of 80,000 ± 10,000, determined by high performance liquid chromatography on a calibrated SW500 column. Whilst the P. c. chabaudi and P. berghei activity co‐migrate in native polyacrylamide gels, that of P. falciparum migrates more slowly. The three enzymes can be selectively inhibited by ortho‐phenanthroline and are thus metallo‐aminopeptidases; however, in contrast to other aminopeptidases the metal co‐factor does not appear to be Zn2+.