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PubMed1986

Characterization of protein-linked oligosaccharides in trypanosomatid flagellates.

Protein-linked, endo-beta-N-acetylglucosaminidase H-sensitive oligosaccharides were isolated from several trypanosomatids incubated with [U-14C]glucose. Structural analysis of the compounds revealed that Man9GlcNAc2 was the oligosaccharide transferred from dolichol-P-P derivatives to proteins in Trypanosoma dionisii, Trypanosoma conorhini, Leptomonas samueli and Herpetomonas samuelpessoai and Man6GlcNAc2 in Blastocrithidia culicis and Leishmania adleri. In all cases, transiently glucosylated compounds were detected: Glc1Man7-9GlcNAc2 in T. dionisii, T. conorhini, L. samueli; Glc1Man9GlcNAc2 in H. samuelpessoai, Glc1Man6GlcNAc2 in B. culicis and Glc1Man6GlcNAc2 and Glc1Man5GlcNAc2 in L. adleri. The mechanism of protein glycosylation in T. dionisii and T. conorhini appeared to be similar to that described before for Trypanosoma cruzi epimastigotes, although some differences were found between the structures of the main isomers of Man7GlcNAc2 and Man8GlcNAc2 present in T. conorhini and T. cruzi. Differences between the mechanisms of glycosylation occurring in Leishmania mexicana and L. adleri were also found: Man6GlcNAc2 in the latter microorganism was demannosylated to Man5GlcNAc2, a step not detected in the former parasite. A novel substituent in N-linked high mannose-type oligosaccharides was found in L. samueli and H. samuelpessoai: galactose in the furanose configuration. In the latter trypanosomatid, Man9GlcNAc2 was demannosylated only to Man8GlcNAc2, whereas in all other parasites in which the same oligosaccharide was transferred to proteins, Man5-7GlcNAc2 were also detected.

Animals↗
PubMed1987

Phosphomonoesterases of Leishmania mexicana mexicana and other flagellates.

Amastigotes and log-phase promastigotes of Leishmania mexicana mexicana contained distinct acid phosphatase, 3'-nucleotidase and 5'-nucleotidase activities, distinguishable by their response to pH and inhibitors. Both tartrate-sensitive and tartrate-resistant acid phosphatase were present in the two forms, amastigotes possessed less tartrate-resistant acid phosphatase than promastigotes. A tartrate-sensitive acid phosphatase was secreted into the medium in large amounts during the growth in vitro of L. m. mexicana promastigotes. The 5'-nucleotidase activity of both parasite forms was inhibited by ammonium molybdate, sodium tartrate and, to less extent, by sodium fluoride whereas 3'-nucleotidase was inhibited by EDTA. All three activities were shown to be present on the external surface of both amastigotes and promastigotes. The three phosphomonoesterase activities were also detected in extracts of L. m. amazonensis, L. donovani, L. tarentolae, Crithidia fasciculata, Herpetomonas muscarum muscarum, H.m. ingenoplastis and Trichomitus batrachorum whereas 5'-nucleotidase was not detected in Trypanosoma brucei brucei extract and 3'-nucleotidase was absent from extracts of Trichomonas vaginalis and Tritrichomonas foetus.

5'-Nucleotidase↗
PubMed1988

Demonstration of glycosomes (microbodies) in the Bodonid flagellate Trypanoplasma borelli (Protozoa, Kinetoplastida).

Homogenates of Trypanoplasma borelli were subjected to subcellular fractionation by sequential differential and isopycnic centrifugation in sucrose. Glycerol-3-phosphate dehydrogenase and the glycolytic enzymes, glucosephosphate isomerase and triosephosphate isomerase, as well as the peroxisomal marker enzyme catalase were mainly, or in part, associated with sedimentable particles that had a buoyant density in sucrose of 1.22 g cm-3. Moreover, triosephosphate isomerase exhibited latency, both in total homogenates and in the particulate fraction. Electron microscopy of thin sections of T. borelli revealed the presence of microbodies that gave a positive reaction for catalase. Pyruvate kinase behaved as a typical soluble enzyme. It was stimulated by micromolar concentrations of fructose 2,6-bisphosphate and this stimulation was counteracted by inorganic phosphate in the millimolar range. The enzymes involved in the synthesis and degradation of fructose 2,6-bisphosphate, 6-phosphofructo-2-kinase and fructose-2,6-bisphosphatase, were both present in T. borelli and behaved as soluble enzymes. We conclude that in T. borelli the glycolytic pathway is compartmentalized in a way similar to that found in another Kinetoplastid family, the Trypanosomatidae, where seven glycolytic enzymes and two enzymes of glycerol metabolism are associated with glycosomes. Apparently the presence of glycosomes is a characteristic of all Kinetoplastida.

Animals↗
PubMed1988

Flagellar wave reversal in the kinetoplastid flagellate Crithidia oncopelti.

Living Crithidia oncopelti cells swim through their environment by means of tip-to-base waves on their single flagellum. The cells are able to re-orient themselves by using a short burst of asymmetrical base-to-tip waves. All points on a flagellum are capable of initiating waves. Placing a population of cells in a medium of high viscosity initially produces a large number of organisms beating in the reverse mode. An individual cell has a random "switching" behavior. Viscosity affects the frequency of forward and reverse waves in different ways. The concentration of free Ca++ ions determines the direction of wave propagation in reactivated axonemes. Calmodulin may play a role in mediating the Ca++ dependence of wave direction.

Animals↗
PubMed1985

A cytostome/cytopharynx in green euglenoid flagellates (Euglenales) and its phylogenetic implications.

The green, phototrophic euglenoid, Colacium libellae, has a vestigial cytostome and cytopharynx. The membrane forming the simple pocket is decorated with a dense, microfilamentous mesh. The mesh binds the pocket to a band of reinforcing microtubules which is homologous with the bodonid MTR. The opening of the cytostome at the reservoir-canal transition zone implies that the phototrophic euglenoid canal is formed by the invagination of the vestibulum of the phagotrophic euglenoids. Our observations support the hypothesis that the phagotrophic euglenoids arose from a bondonid ancestor and gave rise to the phototrophs by chloroplast acquisition.

Animals↗
PubMed1985

Purine phosphoribosyltransferases of Leishmania mexicana mexicana and other flagellate protozoa.

Amastigotes and cultured promastigotes of Leishmania mexicana mexicana and L. m. amazonensis, cultured promastigotes of L. donovani and L. tarentolae, and the culture forms of Crithidia fasciculata, Herpetomonas muscarum muscarum and H. m. ingenoplastis all possessed four phosphoribosyltransferase (PRTase) activities: adenine PRTase, hypoxanthine PRTase, guanine PRTase and xanthine PRTase. The enzymes of L. m. mexicana required divalent cations for activity; Mn2+ or Co2+ produced maximal activity in most cases. Hypoxanthine PRTase, guanine PRTase and xanthine PRTase from all organisms were sedimentable in part, suggesting that they may occur within glycosomes. The enzymes of L. m. mexicana cultured promastigotes were inhibited by a range of purine analogues.

Adenine Phosphoribosyltransferase↗
PubMed2005

Strains of the heterotrophic flagellate Bodo designis from different environments vary considerably with respect to salinity preference and SSU rRNA gene composition.

The morpho species Bodo designis is widespread and abundant globally in highly contrasting terrestrial and aquatic ecosystems. Whether the forms of Bodo designis from contrasting environments are conspecific, i.e. largely genetically identical, or whether they merely share the external morphology is presently not known. We examined the ability of different strains of Bodo designis isolated from different environments at different geographical sites to survive and grow at a salinity range of 0.5-45%. The Bodo designis strains from marine, freshwater, and terrestrial environments showed a different ability to cope with altered physiological conditions. Most of the tested strains were only able to tolerate a small salinity range, whereas others were able to withstand all tested salinity levels. We further examined the phylogenetic relationship between the different strains by sequencing the small subunit (SSU) rRNA gene. The resulting phylogenetic analyses suggest a huge genetic variation within Bodo designis, and also imply that Dimastigella and Rhyncomonas are developed inside Bodo designis. If the biological species concept is used, the genetic differences as well as the physiological barriers between the different strains of Bodo designis, would suggest that they should be assigned to different species.

Animals↗
PubMed2006

The evolution and diversity of kinetoplastid flagellates.

Five years ago, little was known about kinetoplastid evolution. Recent improvements in the taxon sampling for nuclear rRNA genes and several protein markers have transformed this understanding. Parasitism evolved at least four times in kinetoplastids. Obligate parasitic trypanosomatids are a relatively 'derived' group within kinetoplastids; their closest relative is likely to be the free-living Bodo saltans, and the ancestral trypanosomatids were probably parasites of insects. Although subject to recent controversy, trypanosomes (genus Trypanosoma) probably constitute a monophyletic group. Several unusual features of trypanosomatid genomes (e.g. trans-splicing, mitochondrial RNA editing and intron poverty) are common in kinetoplastids and pre-date the adoption of parasitism. The framework of relationships is becoming robust enough for real comparative approaches to be used to understand kinetoplastid biology.

Animals↗
PubMed1976

Swimming of flagellated microorganisms.

The swimming motion of a microorganism with a single flagellum is investigated for both helical and planar flagellar motion. First the force and torque exerted on the organism by the surrounding fluid are calculated in terms of the specified flagellar motion and the unknown linear and angular velocity of the whole organism. Then these unknown velocities are determined by the condition that the net force and torque on the organism are zero. Using these velocities, the trajectory of the organism is found. In the case of helical flagellar motion, the path of the entire organism is found to be a helix of small radius. The axis of the flagellum is not parallel to the axis of the helical path, but makes a small angle with it and precesses around it. If the flagellar motion is planar and sinusoidal, then the trajectory of the organism is found to be a straight line with small oscillations about it. Each point of the flagellum also oscillates longitudinally with double the frequency of the transverse oscillation, producing a figure eight motion. However if the flagellar motion is planar and asymmetric, then the trajectory is found to be a circle with small superposed oscillations. These conclusions account for the observed helical and circular trajectories of sperm, and for the figure eight motion of the tip of the flagellum in the planar case.

Animals↗
PubMed2001

Arginine kinase of the flagellate protozoa Trypanosoma cruzi. Regulation of its expression and catalytic activity.

In epimastigotes of Trypanosoma cruzi, the etiological agent of Chagas' disease, arginine kinase activity increased continuously during the exponential phase of growth. A correlation between growth rate, enzyme-specific activity and enzyme protein was observed. Arginine kinase-specific activity, expressed as a function of enzyme protein, remains roughly constant up to 18 days of culture. In the whole range of the culture time mRNA levels showed minor changes indicating that the enzyme activity is post-transcriptionally regulated. Arginine kinase could be proposed as a modulator of energetic reserves under starvation stress condition.

Animals↗