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PubMed1976

Desulfuromonas acetoxidans gen. nov. and sp. nov., a new anaerobic, sulfur-reducing, acetate-oxidizing bacterium.

Anaerobic sea or fresh water media with acetate and elemental sulfur yielded enrichments of a new type of strictly anaerobic, rod-shaped, laterally flagellated, Gram-negative bacterium. Three pure culture-strains from different sulfide-containing sea water sources were characterized in detail and are described as a new genus and species Desulfuromonas acetoxidans. The new bacterium is unable to ferment organic substances; it obtains energy for growth by anaerobic sulfur respiration. Acetate, ethanol or propanol can serve as carbon and energy source for growth; their oxidation to CO2 is stoichiometrically linked to the reduction of elemental sulfur to sulfide. Organic disulfide compounds, malate or fumarate are the only other electron acceptors used. Butanol and pyruvate are used in the presence of malate only; no other organic compounds are utilized. Biotin is required as a growth factor. The following dry weight yields per mole of substrate are obtained: in the presence of sulfur: 4.21 g on acetate, 9.77 g on ethanol; in the presence of malate: 16.5 g on acetate, 34.2 g on ethanol and 46.2 g on pyruvate. Accumulations of cells are pink; cell suspensions exhibit absorption spectra resembling those of c-type cytochromes (abs. max. at 419, 523 and 553 nm). Malate-ethanol grown cells contain a b-type cytochrome in addition. In the presence of acetate, ethanol or propanol, Desulfuromonas strains form robust growing syntrophic mixed cultures with phototrophic green sulfur bacteria.

Acetates↗
PubMed1981

Clostridium aceticum (Wieringa), a microorganism producing acetic acid from molecular hydrogen and carbon dioxide.

Spores of Clostridium aceticum (Wieringa) from 1947 have been revived, and a study for a redescription of this microorganism has been carried out. C. aceticum was Gram negative. The cells were rodshaped and peritrichously flagellated. Round spores were formed in terminal position. The DNA contained 33 mol % guanine plus cytosine. The organism was obligately anaerobic and grew either chemolithotrophically with H2 + CO2 or chemoorganotrophically with compounds such as fructose, L-glutamate, L-malate or pyruvate. H2 and CO2 were converted to acetic acid according to the following equation: 2CO2 + 4H2 leads to CH3COOH + 2H2O The optimal temperature for growth was 30 degrees C. The optimal pH for chemolithotrophic growth was 8.3. The doubling times for chemolithotrophic and chemoorganotrophic growth were 25 and 8 h, respectively.

Acetates↗
PubMed1975

Effect of external factors on phototaxis of Chlamydomonas reinhardtii. I. Light.

1. A fully automated phototaxis monitoring device is described for measuring photo-topotactic responses of flagellated organisms. 2. Photokinesis can be demonstrated in Chlamydomonas cells only after a dark period of about 72 hrs. 3. Pre-darkening of a few hours duration raises the phototactic disposition, whereas pre-illumination has no significant effect. 4. Circadian rhythms can be initiated by only one period of darkness or lower light intensity, whereas a period of higher intensity does not induce rhythms. The period length of the circadian rhythms is about 24 hrs.

Cell Movement↗
PubMed1977

A new anaerobic, sporing, acetate-oxidizing, sulfate-reducing bacterium, Desulfotomaculum (emend.) acetoxidans.

A new strictly anaerobic, polarly flagellated, sporing, acetate-oxidizing, sulfate-reducing bacterium was isolated from anaerobic fresh or sea water mud samples. The oxidation of acetate to CO2 is stoichiometrically linked to the formation of H2S from sulfate. Ethanol, butanol and butyrate are also used. Hydrogen, lactate or pyruvate are not used as electron donors; organic substances are not fermented. A cytochrome of the b-type and a supposed sulfite reductase, P582, were detected spectrophotometrically. An emended description of the genus Desulfotomaculum is proposed which includes the new bacterium as the species Desulfotomaculum acetoxidans.

Acetates↗
PubMed1995

Phylogenetic position of the Chromista plastids based on small subunit rRNA coding regions.

The kingdom Chromista contains eukaryotic organisms with tubular mastigonemes on the leading flagellum of their bi-flagellated stages, and plastids within a chloroplast endoplasmic reticulum (CER). The complex series of events leading to the formation of the CER is hypothesized to have occurred only once. Thus, all organisms with plastid-CER connections are believed to be monophyletic and derived from a single secondary endosymbiotic event. Analyses of sequence data from the 16s rRNA gene from three of the four Chromista pigmented classes indicate that these algae are not monophyletic. The validity of the kingdom Chromista and the number of secondary plastid endosymbioses are questioned.

Base Sequence↗
PubMed1985

Circadian oscillators, cell cycles, and singularities: light perturbations of the free-running rhythm of cell division in Euglena.

The free-running circadian rhythm of cell division in the algal flagellate, Euglena gracilis (Z) was perturbed by 3-h light signals of varying intensities imposed at different circadian times (CT). Light pulses within the range of 700 to 7,500 lux were found to yield the same 'strong' (Type 0) phase response curve (PRC) comprising both advance and delay phase shifts as great as 15 h. Dark signals generated a PRC of reduced amplitude with very little, if any, phase advance being observed. Light perturbations of lower intensity, however, elicited quite different responses if applied at a quite specific circadian time: A 40- to 400-lux pulse given at approximately CT 0 (late subjective night) induced total arrhythmicity, and the culture reverted to asynchronous, exponential growth. Different degrees of arrhythmicity were induced by the same low-intensity perturbations (I*) given slightly before or after this sensitive phase point (T*), but if imposed at other circadian times, they generated normal type 0 phase resetting. The demonstration of the existence of this critical pulse (T*, I*) provides further evidence that the cell division cycle of Euglena (and presumably other microorganisms) is regulated by a circadian oscillator and, in particular, by one having limit cycle dynamics.

Biophysical Phenomena↗
PubMed1982

Interaction of Trypanosoma cruzi with macrophages in vitro: dissociation of the attachment and internalization phases by low temperature and cytochalasin B.

Chicken macrophages, obtained by cultivation of blood monocytes, were infected with epimastigote and bloodstream trypomastigote forms of Trypanosoma cruzi strain Y. The percentage of macrophages containing parasites within parasitophorous vacuoles and of flagellates attached to cell surfaces was determined. By incubation of the macrophages at 4 degrees C or in the presence of cytochalasin B it was possible to dissociate the attachment from the internalization phases in the process of infection of macrophages. Both treatments had a marked effect on the internalization of epimastigote and trypomastigote forms. Cytochalasin B treatment and placement of the macrophages at 4 degrees C before infection inhibited this process by about 99 and 96%, respectively. These results suggest that endocytosis is the principal mechanism of internalization of T. cruzi by macrophages. They show also that epimastigote and trypomastigote forms of T. cruzi have a different rate of adhesion to the macrophage surface.

Adhesiveness↗
PubMed1984

Scanning electron microscopic studies of Trypanosoma cruzi in the rectum of its vector Triatoma infestans.

The cuticular surface of the rectum of Triatoma infestans and its colonization by a Trypanosoma cruzi strain originating from the same locality as the bugs were studied by scanning electron microscopy at different weeks post infectionem. On the basis of the cuticular folding, the rectum can be subdivided into five regions. The rectal gland has the finest structure and the region anterior to the anus the deepest folds. Try. cruzi always prefers to colonize the rectal gland, while the other regions are colonized in varying densities. Most of the flagellates are epimastigotes (long and short), except in the region at the entrance of the midgut, where trypomastigotes predominate.

Animals↗
PubMed1995

Leishmania donovani: in vitro culture and [1H] NMR characterization of amastigote-like forms.

When Leishmania donovani promastigote forms, were cultured in TC-199 medium at 28 degrees C and subsequently incubated at 38 degrees C, they turned into aflagellate (amastigote-like) forms. A return of the incubation-culture temperature to 28 degrees C these amastigote-like forms to revert to promastigotes. The amastigotes obtained by heat-shock, were viable and retained antigenic capacity being recognized by the sera of naturally infected patients. These forms, remained also capable of multiplying inside the J-774A.1 macrophages. When the amastigote-like forms are kept in culture at 38 degrees C retained their rounded appearance and their biological characteristics for more than 3 months subculturing every 6 days. These amastigote-like forms, when used for subcultures at 28 degrees C, transformed into promastigotes capable of multiplying as flagellate forms. The amastigote-like forms obtained in vitro can be used in biochemical studies related to chemotherapy and immunology studies, as part of an effort to combat this parasite. The end-products of of glycolysis were studied in both the amastigote-like and promastigote forms of L. donovani, by proton magnetic resonance analysis of the culture media. Alanine, succinate, and acetate, were predominant, and to a lesser extent pyruvate, glycine and D-lactate. Our results suggest that both forms of Leishmania use different biochemical strategies to obtain their energy.

Animals↗
PubMed1984

Identification of trypanosomes isolated from reduviidae from north Chile.

Examination of 54 Triatoma infestans from a village near the European Southern Observatory La Silla in Chile and of 9 Triatoma spinolai from the territory of the observatory showed that 10 T. infestans were infected with trypanosomatids. Mice were infected with in vitro cultures initiated with five different trypanosomatid isolates and treated with the immunosuppressive drug cyclophosphamide to increase the parasitemia of the flagellates. Evidence of the presence of T. cruzi was provided by a comparative biometrical analysis of blood trypomastigotes and the occurrence of intracellular amastigotes. Three methods for further identification were used: examination of kDNA ultrastructure, disc electrophoresis of soluble proteins and the Aaptos papillata II lectin induced agglutination. We obtained the following results for all isolates: (1) presence of a central band of the kDNA; (2) T. cruzi specific double bands of the protein patterns; (3) positive reaction with Aaptos papillata II. No differences between the five isolates from Chile and T. cruzi or T. cruzi-like strains from other countries could be observed. Based on these results an infection of the bugs with T. rangeli and T. conorhini could be excluded.

Agglutination Tests↗
PubMed1989

Adherence and surface properties of Tritrichomonas mobilensis, an intestinal parasite of the squirrel monkey.

Adherence properties of the potentially enteropathogenic Tritrichomonas mobilensis were studied in vitro. Axenically cultivated trichomonads readily attached to isolated intestinal epithelial cells and mucus of the squirrel monkey. The kinetics and nature of T. mobilensis cytadherence were microscopically evaluated in cell-suspension assay using Chinese hamster ovary (CHO) cells and in microplate hemagglutination assay with human erythrocytes. Adherence of the parasites to target cells was concentration- and time-dependent; it was inhibited by sialic acid (N-acetylneuraminic or N-glycolylneuraminic acid) and sialyllactose. Neither trypsinization of the flagellates nor their exposure to low temperature (4 degrees C) affected their cytadherence capacities. The data indicate the presence of adhesin(s) with lectin properties on T. mobilensis. Agglutination of live protozoa by animal and plant lectins with various carbohydrate-binding specificities as well as the occurrence of an electron-dense cell coat on plasma membrane suggest marked glycosylation of the parasite surface.

Animals↗
PubMed1995

Occurrence of N-acetyl- and N-O-diacetyl-neuraminic acid derivatives in wild and mutant Crithidia fasciculata.

The cell-surface expression of sialic acids in wild-type Crithidia fasciculata and three drug-resistant mutants (FU(R)11, TR3, and TFRR1) was analyzed using fluorescein-labeled Limulus polyphemus agglutinin (LPA) binding, glycosidase of known sugar specificity, and thin-layer chromatography (TLC). Gas-liquid chromatography-mass spectrometry (GC-MS) analysis using both electron-impact (EI-MS) and chemical ionization (CI-MS) by isobutane with selected ion monitoring (SIM) was also used. The surface location of sialic acid was inferred from LPA binding to whole cells abrogated by previous treatment with neuraminidase. An exception occurred with the TFRR1 strain, which after incubation with neuraminidase showed increased reactivity with the fluorescent lectin. Both N-acetyl- and N-O-diacetyl-neuraminic acids were identified in the flagellates by TLC, with a clear predominance being noted for the former derivative. However, the content of N-O-diacetyl-neuraminic acid was preferentially found in the TFRR1 strain. The GC-MS analysis of the acidic component of the TFRR1 mutant strain confirmed the occurrence of N-acetyl-neuraminic acid (Neu5Ac) by the presence of the diagnostic ions (m/z values: 684 and 594 for CI-MS and 478, 298, and 317 for EI-MS) and also by comparison with the standard Neu5Ac retention time. GC-MS analysis also showed fragments (m/z values: 654 and 564 for CI-MS and 594, 478, 298, and 317 for EI-MS) expected for the 7-O- and 9-O-acetyl-N-acetyl-neuraminic acids (Neu5,7Ac2 and Neu 5,9Ac2, respectively).

Animals↗
PubMed1992

Detection and quantitation of cell-surface sugar receptor(s) of Leishmania donovani by application of neoglycoenzymes.

Promastigote culture forms of the log growth phase of Leishmania donovani stock LRC L 51 were investigated for expression of cell-surface carbohydrate-binding sites using 15 types of a chemically glycosylated enzyme termed neoglycoenzyme. Carbohydrate conjugation and coupling yield were kept constant to ensure that the type of carbohydrate moiety was the only variable feature of the applied tools. Para-aminophenyl derivatives of the following carbohydrate residues were used for the glycosylation of beta-galactosidase from Escherichia coli: beta-D-lactose, beta-D-thiogalactose, alpha-D-mannose, alpha-L-rhamnose, alpha-D-N-acetylgalactosamine, beta-D-N-acetylgalactosamine, beta-D-N-acetylglucosamine, the alpha- and beta-glucosides maltose and cellobiose, beta-D-xylose, alpha-D-mannose-6-phosphate, the alpha-galactoside melibiose, alpha-L-fucose, and beta-D-glucuronic acid as well as sialic acid. Only melibiose, fucose, and glucuronic acid showed no binding affinity for the cultured flagellates; this served as an internal control reaction to exclude any binding to the linker group. This result demonstrates that many but not all sugar types can be recognized by appropriate receptor structure(s) on the surface of the promastigote Leishmania. Transformation of the binding data for neoglycoenzymes exposing lactose, mannose, rhamnose, and N-acetylated hexose residues, which was carried out to obtain the dissociation constants and to estimate the number of binding sites at saturation, revealed KD values of around 100 mM and around 10(4) binding sites for the polyvalent ligands.

Animals↗
PubMed1992

Ultrastructural aspects of Trypanosoma (Megatrypanum) freitasi in co-cultivation with mammalian cells.

Cultures of Trypanosoma (Megatrypanum) freitasi with L929 mouse fibroblasts at 27.5 degrees C were examined by scanning and transmission electron microscopy in an attempt to clarify the processes of colony formation by the epimastigotes and of their attachment to substrata. It was seen that the flagellates occupy intercellular spaces and do not associate with intact fibroblasts. As the trypanosome population increases, ever larger portions of the substratum are cleared of fibroblasts and occupied by conglomerates of epimastigote colonies consisting of about a dozen organisms that attach to the substratum by their anterior extremities and form pyramidal clusters. Attachment of the epimastigotes involves the flagellar membrane, which becomes extraordinarily enlarged and assumes various aspects of broad sheets, filaments and loops over the substratum or along the flagellum, which exhibits a shortened axoneme. Desmosome or hemidesmosome plaques are present when the attachment takes place between membranes or between the membrane and the substratum.

Animals↗
PubMed1993

Trichomonas vaginalis: strain differences in adhesion to plastic and virulence in vitro and in vivo.

Trichomonas vaginalis isolated from clinical cases were grown axenically in TYI-S-33 medium. Various strains of this flagellate showed different adhesion characteristics in medium containing bovine serum or Cohn fractions thereof. These were not inversely related to the time in axenic culture. The adsorption of serum components to the parasites was assessed in relationship to adhesion but in many cases was probably not adhesion-related. All strains tested for virulence in vitro were almost equally cytotoxic for HeLa tissue cultures. However, in infectivity trials, one of these strains exhibited the highest adhesion capability and proved to be the most virulent for mice, and another (cloned) strain with the poorest adhesion capability failed to cause infection. Other strains exhibited lessened virulence following their extended axenic cultivation. It therefore appears that the in vivo pathogenic potential of the parasites growing in axenic culture is inherently strain-dependent. The findings suggest that although adhesion in whole serum-containing medium is sufficient to differentiate between various Trichomonas isolates, it is insufficiently sensitive to correlate adhesion with virulence. It apparently is important to identify the adhesion-mediating factor(s) in serum or in its Cohn fractions IV-1 and IV-4 and to use it (them) to elucidate the possible correlation between the parasite's capacity to adhere and its pathogenicity.

Adsorption↗
PubMed1993

Intracellular lectin-binding sites in symbiont-bearing Crithidia species.

Crithidia oncopelti, C. deanei, and C. desouzai are flagellates of the Trypanosomatidae family that present bacterium-like endosymbionts in their cytoplasm. Direct and indirect lectin-gold labeling techniques were used at the electron microscopic level in Lowicryl K4M-embedded cells to demonstrate the presence of intracellular lectin-binding sites. We used the lectins Ulex europaeus I, Griffonia simplicifolia II, Ricinus communis I, Arachis hypogaea, G. simplicifolia I, Wistaria floribunda, Limulus polyphemus, and Canavalia ensiformis, which recognize alpha-L-fucose, alpha- and beta-N-acetylglucosamine, beta-galactose and beta-N-acetylgalactosamine, beta-galactose, alpha-galactose, beta-N-acetylgalactosamine, sialic acid and alpha-D-mannose, and alpha-D-glucose residues, respectively. The nucleus was the cellular structure most frequently labeled by the lectins. The Golgi complex was seldom labeled, whereas the endoplasmic reticulum and the flagellar pocket presented a large number of binding sites. Symbionts had their two unit membranes weakly labeled by the different lectins but displayed no labeling of the space between the membranes.

Amino Sugars↗
PubMed1994

Detection of trypanosomatid Phytomonas parasitic in plants by polymerase chain reaction amplification of small subunit ribosomal DNA.

To improve the diagnosis of Phytomonas infections in plants, we developed a polymerase chain reaction (PCR) assay using synthetic oligonucleotides complementary to conserved sequences of the 18S small subunit ribosomal (SSU) gene. From 10 ng upward of DNA of cultures of Phytomonas isolated from plants, fruits, and insects, PCR amplified an 800-bp DNA band that, after restriction analysis and probe hybridization, proved to be of 18S rDNA Phytomonas origin. PCR was also done with sap samples of tomatoes experimentally infected with Phytomonas, yielding amplified 800-bp ribosomal DNA bands before any flagellate could be detected by microscopic examination of the fruit sap.

Animals↗
PubMed1983

The ultrastructure of mitotic nuclei of Blastocrithidia triatomae.

The fine structure of mitotic nuclei of the flagellate Blastocrithidia triatomae has been studied by serial thin sections and three-dimensional reconstructions. The sequence of changes during the four stages of mitosis are described. A set of three dense plaques is constantly found in the equatorial stage of mitosis. The microtubular spindle is organized around these plaques. The plaques split into halves at the end of the equatorial stage, and the half-plaques migrate to the spindle ends. Elongation of the mitotic nucleus occurs after the division of the plaques. This elongation is associated with the formation of an interpolar bundle of microtubules. The equatorial spindle is formed by 26-28 microtubules and is 1.5 micrometers long. The nucleolus attaches itself to the nuclear envelope and persists up to the elongational stage; then it disintegrates and is reorganized in daughter nuclei. Mitotic events in B. triatomae are essentially similar to those in Trypanosoma cruzi epimastigotes. As in this hemoflagellate, the dense plaques behave as kinetochores. It is concluded that B. triatomae is probably a haploid organism that contains three chromosomes.

Animals↗