| the common 5' terminal sequence on trypanosome mrnas: a target for anti-messenger oligodeoxynucleotides. | several mature mrnas of trypanosoma brucei were previously shown to have a common 5' terminal sequence of 35 nucleotides (nt) encoded by a separate mini-exon. to verify whether all trypanosome mrnas contain this mini-exon sequence at their 5' end, we have tested oligodeoxynucleotides complementary to different parts of the 35 nt leader sequence for their ability to inhibit translation of total trypanosome mrna. all oligomers tested inhibited translation of trypanosome mrnas in a wheat germ extra ... | 1986 | 3737413 |
| trypanosoma brucei: cis-aconitate and temperature reduction as triggers of synchronous transformation of bloodstream to procyclic trypomastigotes in vitro. | synchronous transformation of the monomorphic trypanosoma brucei 427 variant clone mitat 1.4 (117) from bloodstream to procyclic trypomastigotes was studied in modified minimum essential medium plus 15% inactivated horse serum. repression of variant surface glycoprotein synthesis, subsequent morphological transformation, and growth of procyclic cells was triggered by the simultaneous action of two signals: a reduction in temperature from 37 to 27 c and the addition of cis-aconitate. repression o ... | 1986 | 3743718 |
| mapping of vsg genes on large expression-site chromosomes of trypanosoma brucei separated by pulsed-field gradient electrophoresis. | we have modified the conditions for pulsed-field gradient electrophoresis of trypanosoma brucei (strain 427) to resolve large chromosomes, which previously comigrated, into five distinct chromosome bands. mapping of four different variant surface glycoprotein (vsg) genes, which were duplicatively activated in eight independent vsg gene switching events during later stages of infection, has shown that the activated gene is invariably translocated to the same chromosome band. also, we have examine ... | 1986 | 3744050 |
| purification and characterization of the membrane-form variant surface glycoprotein hydrolase of trypanosoma brucei. | the conversion of the membrane-form variant surface glycoprotein (mfvsg) of the unicellular parasitic flagellate trypanosoma brucei to soluble variant surface glycoprotein and sn-1,2-dimyristoyl glycerol is catalyzed by an endogeneous, membrane bound phospholipase c-like hydrolase. using a monoclonal antibody against the enzyme the hydrolase was purified 3,000-fold with a yield of 32%. the enzyme has a molecular weight of 39,000 as determined by polyacrylamide gel electrophoresis in the presence ... | 1986 | 3745171 |
| identification of a glycolipid precursor of the trypanosoma brucei variant surface glycoprotein. | the variant surface glycoprotein (vsg) of trypanosoma brucei has a glycolipid covalently attached to its c terminus. this glycolipid, which anchors the protein to the cell membrane, is attached to the vsg polypeptide within 1 min after translation (bangs, j. d. hereld, d., krakow, j.l., hart, g. w., and englund, p. t. (1985) proc. natl. acad. sci. u. s. a. 82, 3207-3211). this rapid processing suggests that, prior to incorporation, the glycolipid may exist in the cell as a preformed precursor wh ... | 1986 | 3745182 |
| suppression of immune responses of locusts to trypanosomatid flagellates by concomitant mermithid infection. | | 1986 | 3745930 |
| hydrogen peroxide metabolism in trypanosoma brucei. | contrary to previous reports in the literature, bloodstream forms of the haemoflagellate protozoan trypanosoma brucei brucei are not deficient in their ability to metabolize hydrogen peroxide, although they either lack or only possess the normal enzymes for h2o2 detoxification, catalase (ec 1.11.1.6) and glutathione peroxidase (ec 1.11.1.9), at extremely low levels. the hydrogen peroxide which is consumed appears to be reduced by nadph derived from glucose via the pentose phosphate pathway. this ... | 1986 | 3748070 |
| an enzyme-linked immunosorbent assay for the detection of antibodies to trypanosoma (t.) brucei evansi in camels (camelus dromedarius) using peroxidase-conjugated protein a. | serum samples from dromedary camels naturally and experimentally infected with trypanosoma (t.) brucei evansi were examined by means of the elisa, using either an anti-camel or a protein a conjugate. the protein a horseradish peroxidase conjugate was found to bind to camel igg and thus to be a suitable alternative to the anti-camel conjugate. results obtained from both tests showed that the respective values correlate significantly. | 1986 | 3749736 |
| in vitro cultivation of african stocks of trypanosoma (trypanozoon) brucei evansi. | | 1986 | 3753050 |
| influence of heat stress on experimental trypanosoma brucei brucei infection in mice. | | 1986 | 3753052 |
| [duration of the preventive action of diminazene aceturate on experimental infection of nmri mice with metacyclic forms of trypanosoma brucei brucei]. | | 1986 | 3753056 |
| the effect of macromolecular conjugates of daunorubicin on nuclear ultrastructure in trypanosoma brucei rhodesiense. | the effects of free and conjugated daunorubicin on t.b. rhodesiense in vitro are described. free drug caused nucleolar lesions ranging from segregation to complete fragmentation. at equimolar concentrations a soluble bovine serum albumin conjugate with a stable succinyl linkage (d-bsas) produced no ultrastructural lesions whereas a conjugate with a labile glutaraldehyde linkage (d-bsag) and a conjugate linked to large agarose beads (d-ag) produced similar though less severe lesions than free dru ... | 1986 | 3757066 |
| a phospholipase c from trypanosoma brucei which selectively cleaves the glycolipid on the variant surface glycoprotein. | the surface coat of trypanosoma brucei is composed of 10(7) molecules of the variant surface glycoprotein (vsg). each vsg molecule is tethered to the cell membrane by a glycolipid moiety which contains 1,2-dimyristoyl-sn-phosphatidylinositol (ferguson, m. a. j., low, m. g., and cross, g. a. m. (1985) j. biol. chem. 260, 14547-14555). following cell lysis, an endogenous phospholipase c cleaves dimyristoyl glycerol from the glycolipid, releasing soluble vsg. we have purified this enzyme, which we ... | 1986 | 3759991 |
| [antigenic variation of african trypanosomes: molecular aspects]. | | 1986 | 3768582 |
| the effect of citrate/cis-aconitate on oxidative metabolism during transformation of trypanosoma brucei. | monomorphic bloodstream forms of trypanosoma brucei, grown in the mammal, are deficient in aconitase and 2-oxoglutarate dehydrogenase and they do not respire in the presence of the substrates citrate, cis-aconitate, succinate, proline or 2-oxoglutarate. when grown in vitro low levels of aconitase, succinate oxidase and proline oxidase are detected. addition of citrate/cis-aconitate at 37 degrees c to bloodstream forms leads to the formation of aconitase and proline oxidase. most cells undergo an ... | 1986 | 3769918 |
| esters of 3,4-dihydroxybenzoic acid, highly effective inhibitors of the sn-glycerol-3-phosphate oxidase of trypanosoma brucei brucei. | alkyl esters of 3,4-dihydroxybenzoic acid are inhibitors of the sn-glycerol-3-phosphate oxidase system of trypanosoma brucei brucei in vitro and have significant trypanocidal activity in vivo when combined with glycerol. while the parent acid has little inhibitory activity in vitro, the esters are highly active with activity increasing as the chain length of the esterifying alcohol increases. the n-dodecyl ester was more than 400 times as active as salicylhydroxamic acid and 15 times more active ... | 1986 | 3773935 |
| regulation of parasite-specific antibody responses in resistant (c57bl/6) and susceptible (c3h/he) mice infected with trypanosoma (trypanozoon) brucei brucei. | after infection with 10(3) t. brucei gutat 3.1, c57bl/6 mice produced antibody responses and controlled the first parasitaemic wave whereas c3h/he mice did not. the inability of c3h/he mice to control parasitaemia resulted from an impaired ability of parasite-induced antibody-containing cells to secrete immunoglobulin. antibody-containing cells in infected c3h/he mice regained the ability to secrete antibody within 24 h after trypanosome elimination by treatment with berenil, suggesting that the ... | 1986 | 3774375 |
| trypanosoma brucei: a fluorescence and spin label study of the membranes of the bloodstream form. | fluidity of the plasma membrane of trypanosoma brucei brucei has been examined with fluorescence and electron spin resonance spectroscopy. fluorescent probes 1,6-diphenyl-1,3,5-hexatriene and 8-anilino-1-naphthalene sulfonate and the spin label probe 5-doxyl stearate have been employed to examine fluidity under a variety of conditions. the temperature dependence of 8-anilino-1-naphthalene sulfonate polarization and of the order parameter s for 5-doxyl stearate reveals phase alterations near 30 c ... | 1986 | 3780935 |
| purification and characterization of a novel glycan-phosphatidylinositol-specific phospholipase c from trypanosoma brucei. | a novel membrane-bound glycan-phosphatidylinositol-specific phospholipase c, which catalyzes the conversion of membrane form variant surface glycoproteins to soluble variant surface glycoproteins, with the release of sn-1,2-dimyristylglycerol, has been isolated from trypanosoma brucei. the activity was solubilized from trypanosome membrane fractions in non-ionic detergent and purified by anion exchange chromatography on deae-cellulose followed by chromatography on phosphatidylinositol-sepharose. ... | 1986 | 3782089 |
| rapid change of the repertoire of variant surface glycoprotein genes in trypanosomes by gene duplication and deletion. | to study the evolution of the variant surface glycoprotein (vsg) repertoire of trypanosomes we have analysed the dna region surrounding the vsg 118 gene in different trypanosome strains. we find a remarkable degree of variation in this area. downstream from the 118 gene a 5.7 x 10(3) base-pair dna segment containing a potential vsg gene has been quadruplicated in strain 427 of trypanosoma brucei, but not in most other strains analysed. the vsg 1.1000 gene, located immediately upstream from the 1 ... | 1986 | 3783693 |
| metacyclic variant surface glycoprotein genes of trypanosoma brucei subsp. rhodesiense are activated in situ, and their expression is transcriptionally regulated. | during the metacyclic stage in the life cycle of trypanosoma brucei subsp. rhodesiense, the expression of variant surface glycoproteins (vsgs) is restricted to a small subset of antigenic types. previously we identified cdnas for the vsgs expressed in metacyclic variant antigen types (mvats) 4 and 7 and found that these vsg genes do not rearrange when expressed at the metacyclic stage (m. j. lenardo, a. c. rice-ficht, g. kelly, k. esser, and j. e. donelson, proc. nathl. acad sci. usa 81:6642-664 ... | 1986 | 3785186 |
| the u2 rna analogue of trypanosoma brucei gambiense: implications for a splicing mechanism in trypanosomes. | we have isolated the gene coding for the u2 analogue in trypanosomes. the 148 nucleotide long u2 rna is capped and transcribed from a single copy gene. the 5' half of the molecule is highly homologous to mammalian u2 rna, while the 3' half does not show any significant sequence homology with the mammalian counterpart. nevertheless, the trypanosome u2 rna can be folded into a secondary structure resembling the one proposed for u2 rna. the presence of a u2 analogue and most likely other u rnas in ... | 1986 | 3786140 |
| comparison of diagnostic techniques during subclinical single infections of trypanosomiasis in goats. | parasitological diagnostic techniques were compared in caprine hosts in which single subclinical infection with trypanosoma vivax, trypanosoma congolense or trypanosoma brucei brucei had been established. the haematocrit centrifuge technique (hct) was the most sensitive for the diagnosis of t. vivax and t. b. brucei while the buffy coat method (bcm) proved superior to all other techniques for t. congolense. except with the miniature anion-exchange/centrifugation technique (maec), each of the con ... | 1986 | 3788024 |
| the clinical manifestations of rhodesian trypanosomiasis: an account of cases contracted in the okavango swamps of botswana. | over 100 years ago, david livingstone reported the presence of tsetse flies in the okavango swamps in northern botswana. they have persisted in the region and recently have been responsible for many cases of rhodesian sleeping sickness caused by trypanosoma rhodesiense in visitors to the area. the clinical manifestations in illustrative cases of this disease are described. one patient who refused treatment died five months after being infected. one patient died of encephalopathy complicating tre ... | 1986 | 3789270 |
| the effects of mammalian milk/colostrum upon trypanosoma brucei rhodesiense. | | 1986 | 3789845 |
| molecular basis of antigenic variation in african trypanosomes. | | 1986 | 3790118 |
| accessibility of trypanosoma brucei procyclic glycosomal enzymes to labeling agents of various sizes and charges. | the high efficiency of glycolysis in trypanosoma brucei has been attributed to impermeability of the glycosomal membrane to most metabolites. however, the strong stimulation of the glycolytic rate by exogenous metabolites and coenzymes in intact glycosomes is only compatible with their accessibility to the internal space. the accessibility of glycosomal enzymes to protein labeling agents of varying charge and size has been investigated. the results show that the glycosomal membrane is permeable ... | 1987 | 3792559 |
| conserved sequences and transcription of the hsp70 gene family in trypanosoma brucei. | five trypanosoma brucei 70-kilodalton heat shock protein-encoding genes (hsp70 genes) were found to be arranged in a tandem array. these hsp70 genes are separated by highly conserved intergenic region sequences of 200 base pairs for one gene and 234 base pairs for the other four genes. this intergenic region sequence is also present in front of the first gene of the tandem array, though at a further distance. all five conserved intergenic regions have sequences that are homologous to the eucaryo ... | 1986 | 3796613 |
| three small rnas within the 10 kb trypanosome rrna transcription unit are analogous to domain vii of other eukaryotic 28s rrnas. | we have localized the six ribosomal rnas (rrnas) which encode the 28s rrna region of trypanosoma brucei. these six rrnas include two large rrnas, 28s alpha (approx. 1840 nt) and 28s beta (approx. 1570 nt), and four small rrnas of approximate sizes 220, 180, 140 and 70 nt. three of these four small rrnas (180, 70 and 140) are found at the 3' end of the 28s rrnas region. sequence analysis of this area shows that these three small rrnas encode domain vii, the last domain of secondary structure in t ... | 1986 | 3797245 |
| characterization of trypanosoma brucei brucei s-adenosyl-l-methionine decarboxylase and its inhibition by berenil, pentamidine and methylglyoxal bis(guanylhydrazone). | trypanosoma brucei brucei s-adenosyl-l-methionine (adomet) decarboxylase was found to be relatively insensitive to activation by putrescine as compared with the mammalian enzyme, being stimulated by only 50% over a 10,000-fold range of putrescine concentrations. the enzyme was not stimulated by up to 10 mm-mg2+. the km for adomet was 30 microm, similar to that of other eukaryotic adomet decarboxylases. t.b. brucei adomet decarboxylase activity was apparently irreversibly inhibited in vitro by be ... | 1986 | 3800910 |
| an improved purification of glycosomes from the procyclic trypomastigotes of trypanosoma brucei. | the glycosomes of in vitro grown procyclic trypomastigote forms of trypanosoma brucei were purified by three different procedures and the results compared by electron microscopy, enzyme assays and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. centrifugation on a self-forming percoll gradient followed by a sucrose gradient centrifugation resulted in the least enriched glycosomal preparation. centrifugation on a pre-formed nycodenz gradient gave an improved preparation but the most ho ... | 1986 | 3807943 |
| transcriptional mapping of leishmania enrietti tubulin mrnas. | we have mapped the mrnas for alpha- and beta-tubulins of leishmania enriettii promastigotes and amastigotes and have demonstrated that each rna contains a 35 nucleotide sequence on its 5' end which is not encoded contiguously with the rest of the message. sequencing of the 5' end of the alpha- and beta-tubulin mrnas revealed that this 35 nucleotide leader sequence is identical in both messages and that it is homologous to the spliced leader found on the 5' end of mrnas in the related parasite tr ... | 1986 | 3807944 |
| expression of a polypeptide containing a dipeptide repeat is confined to the insect stage of trypanosoma brucei. | the protozoan parasite trypanosoma brucei is transmitted between mammalian hosts by the tsetse fly (glossina spp.). trypanosomes ingested by the fly undergo a number of changes in the insect midgut during differentiation to procyclic forms. these include the loss of the variant specific glycoprotein (vsg) coat and the appearance of a common set of procyclic surface antigens. in order to investigate genes other than vsg genes which are expressed only at certain stages of the life cycle, the first ... | 1987 | 3808022 |
| african trypanosomiasis: haematogenic brain parasitism early in experimental infection through bypassing the blood-brain barrier, with considerations on brain trypanosomiasis in man. | a hematogenic invasion of the brain in suckling nmri mice infected with trypanosoma brucei rhodesiense was initiated by means of a mechanical damage of the blood-brain barrier. the brain was punctured after development of a blood infection. brain infection was found in 31 out of 32 animals examined. trypanosomes are initially capable of rapid multiplication. the number of parasites was highest during the 1st week. from the middle of the 2nd week the number of parasites decreased continuously, al ... | 1987 | 3809147 |
| interaction between trypanosoma brucei and the ependymal cell of the choroid plexus. | the fine structure of the normal choroid plexus of rats and mice and of those infected with trypanosoma brucei was examined by transmission and scanning electron microscopy: extracellular trypomastigotes in the perivascular stroma predominate but the evidence presented suggests that they are derived both from stages in the blood and from others undergoing division within ependymal cells, a process which results in destruction of a large proportion of ependymal cells in the parts of choroid plexu ... | 1986 | 3810795 |
| the ventricular ependyma of mice infected with trypanosoma brucei. | the fine structure of ependymal cells lining the cerebral ventricles of normal mice and of mice infected with trypanosoma brucei was examined by transmission electron microscopy. most of the ependymal cells had been stripped from the ventricular surface of the brain in infected animals but some of the remaining ependymal cells contained intracellular trypomastigotes. the same process of stripping had occurred in a single human brain that was included in the series, but intracellular forms were n ... | 1986 | 3810796 |
| the trypanocidal effect of drugs in different parts of the brain. | three parts of the brain, cerebral cortex, lining of ventricle and choroid plexus, are cleared of trypanosomes to different extents by different drugs. there appear to be several barriers preventing drugs from acting in different parts of the brain, the concept of a single "blood-brain barrier" does not account for the phenomena observed. the protection of trypanosomes from certain drugs by the choroid plexus and ventricular wall supports the concept of an intracellular stage of trypanosoma bruc ... | 1986 | 3810797 |
| lectin interactions with the variant surface glycoprotein from trypanosoma brucei brucei incorporated into liposomes. | the variant specific surface glycoprotein from trypanosoma brucei brucei is incorporated into lipid vesicles using 8m urea as an unfolding reagent. pronase treatment of these proteoliposomes removes most of the protein, leaving a glycophospholipopeptide which is the membrane attachment site. we show here that lectins, specific for mannose and galactose are able to recognize oligosaccharide residues on these proteoliposomes, using a straightforward aggregation assay. the relevance of these result ... | 1986 | 3814124 |
| subpellicular and flagellar microtubules of trypanosoma brucei brucei contain the same alpha-tubulin isoforms. | the cytoskeleton of the parasitic hemoflagellate trypanosoma brucei brucei essentially consists of two microtubule-based structures: a subpellicular layer of singlet microtubules, which are in close contact with the cell membrane, and the flagellar axoneme. in addition, the cells contain a small pool of soluble tubulin. two-dimensional gel electrophoretic analysis of the tubulins present in these subcellular compartments revealed two distinct electrophoretic isoforms of alpha-tubulin, termed alp ... | 1987 | 3818788 |
| development of metacyclic forms of trypanosoma brucei sspp. in cultures containing explants of phormia regina meigen. | when procyclic trypanosomes of trypanosoma brucei brucei and trypanosoma brucei rhodesiense were cultivated in nunclon 25 cm2 flasks at 27 c in a liquid medium containing various tissue explants of phormia regina meigen, some of them developed into forms infective for mice. the infective stages were present at various periods of up to 29 days when the cultures were terminated. larger numbers of explants of head-salivary glands than the other tissues used were required to produce infections. infe ... | 1986 | 3819970 |
| ejaculate characteristics of sheep infected with trypanosoma brucei and t vivax: changes caused by treatment with diminazene aceturate. | the effect of trypanosoma brucei and t vivax on the ejaculate of sheep and the rate of recovery with diminazene aceturate treatment was investigated. animals were made to ejaculate once a week before infection, during infection and after treatment. parameters studied were semen volume, semen colour, sperm motility and concentration, percentage dead spermatozoa and sperm morphology. both infections severely affected the quality of the ejaculate although in t vivax infection there was no appreciab ... | 1987 | 3823622 |
| [the sheep: an experimental model for the study of african trypanosomiasis]. | an experimental model of human african trypanosomiasis is realized in sheep with trypanosoma brucei brucei. clinical and biological evolution is comparable to human disease. this model is useful to test efficient drugs and to get a better knowledge about sleeping sickness physiopathology. | 1986 | 3829214 |
| the phosphoglycerate kinases from trypanosoma brucei. a comparison of the glycosomal and the cytosolic isoenzymes and their sensitivity towards suramin. | trypanosoma brucei has two phosphoglycerate kinase (pgk) isoenzymes, one is particle-bound and localized in glycosomes while the other is present in the cytosol. the cytosolic isoenzyme (cpgk) was 900-fold purified from cultured procyclic trypanosomes by hydrophobic interaction chromatography on phenyl-sepharose followed by affinity chromatography on 2',3'-atp-sepharose and had a specific activity of 275 units/mg protein. cpgk was compared with the purified glycosomal isoenzyme (gpgk) from blood ... | 1987 | 3830152 |
| glyceraldehyde-phosphate dehydrogenase from trypanosoma brucei. comparison of the glycosomal and cytosolic isoenzymes. | trypanosoma brucei contains two glyceraldehyde-phosphate (gapdh; ec 1.2.1.12) isoenzymes; one is located in glycosomes and represents 80% of the total activity, whereas the other is present in the cytosol. the purification of the cytosolic gapdh, which is identical in both bloodstream-form and insect-stage trypanosomes, is described, and the enzyme compared with its glycosomal counterpart. cytosolic gapdh is specific for nad. it is a tetrameric enzyme with subunits of 33.5 kda, 5 kda smaller tha ... | 1987 | 3830153 |
| the behaviour of trypanosomes within the midguts of wild-caught tsetse from zimbabwe. | trypanosomes infecting the midgut of wild-caught tsetse from zimbabwe were found on electron microscopic examination to be penetrating the peritrophic membranes and so entering the ecto-peritrophic space in the mycetome region of the midgut. other trypanosomes entered midgut cells, behaviour similar to that previously reported in laboratory-infected tsetse colonies. | 1985 | 3832497 |
| the behaviour of trypanosomes in liberian tsetse. | | 1985 | 3832504 |
| an assay for screening drugs against animal-infective bloodstream forms of trypanosoma brucei brucei in vitro. | a rapid and simple assay for in vitro drug screening has been established using the mammalian feeder layer cell system for continuous cultivation of infective bloodstream forms of trypanosoma brucei brucei. a total of 21 trypanocides have been tested. differences in sensitivity to standard trypanocides were detected among drug-susceptible isolates and strains of t. b. brucei. this assay may thus be of potential use for rapid detection of new drug-resistant isolates of t. b. brucei. | 1985 | 3836123 |
| further studies on acquisition of potential infectivity for man in closely related trypanosoma trypanozoon brucei clones. | twelve clones were isolated from relapsing populations in an infection initiated with a clone-derived human serum resistant trypanozoon. isolates were serotyped by the immunotrypanolysis test and four distinct variable antigen types (vats) designated witat 4, 5, 6 and 7 were identified. contemporaneous blood incubation infectivity testing (biit) showed that most clones isolated in the course of infection were resistant to normal human serum while some clones isolated after series of relapses wer ... | 1985 | 3836215 |
| the spliced leader sequence of trypanosoma brucei has a potential role as a cap donor structure. | trypanosoma brucei brucei and other trypanosomatid species are unique among eucaryotes because transcription of their protein-coding genes is discontinuous. the 5' ends of their mrnas consist of an identical 35-nucleotide spliced leader which is encoded at a separate locus from that for the body of the protein-coding transcript. we show here that the spliced leader transcript contains a 5' cap structure and suggest that at least one function of the spliced leader sequence is to provide a cap str ... | 1985 | 3837191 |
| conservation of structure detected in two trypanosome surface glycoproteins by amino acid sequence alignment. | the predominant molecule exposed to antibody on the surface of trypanosoma brucei is a glycoprotein of about 60 000 molecular weight which varies in amino acid sequence. the complete sequences of two such variable surface glycoproteins (vsgs) from randomly isolated, different antigenic types of trypanosomes were compared by amino acid sequence alignment. homologous sequences were found distributed over various regions of the vsgs. particularly good homology was observed between residues 16-34, 9 ... | 1985 | 3838798 |
| trypanosoma brucei: a surface antigen mrna is discontinuously transcribed from two distinct chromosomes. | the mrnas for variant surface glycoproteins (vsgs) and many other proteins in trypanosoma brucei start with the same sequence of 35 nucleotides, encoded by a separate mini-exon. there are approximately 200 mini-exon genes per trypanosome and these are highly clustered on large chromosomes. we have found two trypanosome variants that express a vsg gene located on a small, 225-kb chromosome. each gene yields a mrna containing the 35-nucleotide sequence even though the 225-kb chromosome does not co ... | 1985 | 3839457 |
| stimulation of trypanosoma brucei pyruvate kinase by fructose 2,6-bisphosphate. | the activity of pyruvate kinase present in a crude extract of the bloodstream form of trypanosoma brucei was greatly increased by fructose 2,6-bisphosphate, which converted the saturation curve for phosphoenolpyruvate from a sigmoid into a hyperbola with no change in v. phosphate and arsenate had an effect opposite to that of fructose 2,6-bisphosphate and the apparent ka for fructose 2,6-bisphosphate was shifted from 75 nm to 1.5 microm by the presence of 5 mm phosphate. fructose 1,6-bisphosphat ... | 1985 | 3841061 |
| enzyme variation in t. brucei ssp. ii. evidence for t. b. rhodesiense being a set of variants of t. b. brucei. | a collection of stocks of trypanosoma brucei rhodesiense isolated in kenya have been examined for electrophoretic variation in 20 enzymes. the results obtained have been analysed in order to determine whether these trypanosomes are diploid and undergo mating and to determine the genetic distance between t. b. rhodesiense, t. b. brucei and t. b. gambiense. the enzyme electrophoretic markers were further used in experiments involving cyclically transmitted mixtures of stocks aimed at detecting gen ... | 1985 | 3856830 |
| rapid processing of the carboxyl terminus of a trypanosome variant surface glycoprotein. | the variant surface glycoprotein of the parasite trypanosoma brucei contains a glycolipid of unknown structure covalently attached to its cooh terminus. we have shown, by using metabolic labeling with [35s]methionine or [3h]myristic acid, precipitation with specific antibodies, and nadodso4/polyacrylamide gel electrophoresis, that this glycolipid is attached to the variant surface glycoprotein polypeptide within 1 min after its translation. | 1985 | 3858818 |
| differential expression of mitochondrial genes between life cycle stages of trypanosoma brucei. | the mitochondrial respiratory system is differentially produced during the life cycle of the parasitic protozoan, trypanosoma brucei. we have found 14 transcripts that are derived from a maxicircle (mitochondrial dna) region that contains sequences homologous to cytochrome c oxidase subunits i and ii, unassigned reading frame 1 from mitochondrial dna of other organisms, and two other open reading frames. ten of these transcripts occur as pairs that differ in size by approximately equal to 200 nu ... | 1985 | 3858825 |
| calmodulin genes in trypanosomes are tandemly repeated and produce multiple mrnas with a common 5' leader sequence. | in trypanosoma brucei gambiense, the ca2+ binding protein calmodulin is encoded by three identical tandemly repeated genes. the transcripts of these genes consist of several rna species similar in size. a 35-nucleotide spliced leader sequence is present at the 5' end of each mrna but is not encoded by dna contiguous to these genes. we have identified two different sites for the fusion of the leader to the mrna. these results strongly support the idea that a novel, possibly discontinuous, transcr ... | 1985 | 3858856 |
| molecular genetics of antigenic variation in trypanosomes. | | 1985 | 3870638 |
| high and low responsiveness of bovine lymphocytes to trypanosoma brucei in vitro: lack of correlation with resistance to trypanosomiasis. | bovine peripheral blood lymphocytes (pbl) were stimulated to proliferate in vitro by live, irradiated or freeze-thawed trypanosoma brucei, but not by the isolated variant surface glycoprotein. the optimal dose was 10(5) trypanosomes per 5 x 10(5) lymphocytes in 0.2 ml. maximal proliferation was at day 5. of the 98 cattle tested, 36 were high-responders (stimulation indexes 20-104), 49 were low or non-responders (si 1-10) and 13 were intermediate. the responder status of individual animals did no ... | 1985 | 3871728 |
| suppressor factor of t-cell activation and decreased interleukin 2 activity in experimental african trypanosomiasis. | spleen cells from trypanosoma brucei-infected balb/c mice were unable to respond to a t-cell mitogen, concanavalin a. moreover, they were unable to produce detectable amounts of the growth factor required for t cell proliferation, interleukin 2. in addition, supernatants from 24-h in vitro cultures of these cells produced a slight but detectable suppressive activity of the interleukin 2-dependent proliferation of a t-cell line. infected spleen cells also suppressed the response of t. brucei-immu ... | 1985 | 3876993 |
| structure and transcription of a telomeric surface antigen gene of trypanosoma brucei. | the gene encoding variant surface glycoprotein 221 in trypanosoma brucei is located adjacent to a chromosome end and can be activated with or without a concomitant gene duplication. to test whether transcription initiates within the cloned segment of the 221 gene, we analyzed nascent and stable transcripts. we show here that the 221 coding region and 8.5 kilobases of adjacent upstream dna are transcribed into nascent rna at a similar rate when gene 221 is activated without duplication. since onl ... | 1985 | 3879972 |
| trypanothione: a novel bis(glutathionyl)spermidine cofactor for glutathione reductase in trypanosomatids. | glutathione reductase from trypanosomes and leishmanias, unlike glutathione reductase from other organisms, requires an unusual low molecular weight cofactor for activity. the cofactor was purified from the insect trypanosomatid crithidia fasciculata and identified as a novel glutathione-spermidine conjugate, n1,n8-bis(l-gamma-glutamyl-l-hemicystinyl-glycyl)spermidine, for which the trivial name trypanothione is proposed. this discovery may open a new chemotherapeutic approach to trypanosomiasis ... | 1985 | 3883489 |
| comparative study of the ribosomal rna from leishmania and trypanosoma. | the ribosomal rna from several stocks of the genera leishmania and trypanosoma were studied by gel electrophoresis, sedimentation on sucrose density gradients and rna/dna hybridization experiments. three major components were observed after electrophoresis in polyacrylamide gels (page-sds), the relative molecular masses being respectively: x1 = 0.83 megadaltons, x2 = 0.63 megadaltons and x3 = 0.54 megadaltons for leishmania rna; and x1 = 0.86 megaldaltons, x2 = 0.78 megadaltons, and x3 = 0.58 me ... | 1985 | 3886897 |
| trypanosoma brucei: analysis of relapsing populations in sensitive and resistant breeds of cattle. | the clone ditat 1.1 of trypanosoma brucei brucei was injected into four bovids, and clones obtained from successive waves of parasitemia were used to study the expressed variant-specific surface glycoprotein repertoire. twenty-four clones were obtained which could be classified into 12 different variable antigen types, in addition to the clone injected, using agglutination or immunofluorescence with monospecific antisera. the variable surface glycoproteins of the 25 clones were extracted using t ... | 1985 | 3894044 |
| cultivation of african and south american trypanosomes of medical or veterinary importance. | | 1985 | 3896374 |
| biosynthesis, attachment and release of variant surface glycoproteins of the african trypanosome. | | 1985 | 3896675 |
| glycosylation of the variant surface antigens of trypanosoma brucei. | | 1985 | 3896676 |
| regulation of parasitaemia in mice infected with trypanosoma brucei. | | 1985 | 3896678 |
| sulphydryl-dependent enzymes from african trypanosomes. | | 1985 | 3898094 |
| molecular identity and location of invariant antigens on trypanosoma brucei rhodesiense defined with monoclonal antibodies reactive with sera from trypanosomiasis patients. | monoclonal antibodies (mabs) which are reactive with several antigenically distinct variable antigen types were prepared by immunization with trypanosoma brucei rhodesiense. certain mabs were shown to be specific for members of the genus trypanosoma and not reactive with leishmania spp. or plasmodium falciparum by the indirect immunofluorescence assay. these genus-specific mabs were used to identify the molecular location of these invariant antigen determinants in whole t. brucei rhodesiense ant ... | 1985 | 3905617 |
| adenosine cycle in african trypanosomes. | african trypanosomes can convert adenosine to adenosine monophosphate. however, in trypanosoma brucei, as in t. vivax and t. congolense, most of the adenosine is broken down to adenine before conversion to the nucleotide by adenine phosphoribosyltransferase. trypanosoma brucei and t. vivax use the purine nucleoside hydrolase for adenosine cleavage while t. congolense uses purine nucleoside phosphorylase for the nucleoside cleavage. trypanosoma vivax also deaminates adenine to hypoxanthine before ... | 1985 | 3920982 |
| catalytic irreversible inhibition of trypanosoma brucei brucei ornithine decarboxylase by substrate and product analogs and their effects on murine trypanosomiasis. | ornithine decarboxylase from trypanosoma brucei brucei was inhibited by several substrate (ornithine) and product (putrescine) analogs both in vitro and in vivo. since alpha-difluoromethylornithine is effective for the treatment of experimental and clinical african trypanosomiasis, it was possible that the more potent ornithine and putrescine analogs might be more active in treating the disease. however, only alpha-monofluoromethyldehydroornithine methyl ester was more potent than alpha-diflurom ... | 1985 | 3924048 |
| developmental cycles and biology of pathogenic trypanosomes. | | 1985 | 3928017 |
| application of new technologies to epidemiology. | | 1985 | 3928018 |
| conservation of a 29-base-pair sequence within maxicircle ars fragments from six species of trypanosomes. | the maxicircles from trypanosoma brucei, herpetomonas samuelpessoai, leptomonas seymouri, and phytomonas davidi were examined for the presence of a 29-bp sequence termed cf29 that has been found in the ars 189 sequence from the crithidia fasciculata maxicircle and in lt-ars 189 from the maxicircle of leishmania tarentolae. the cf29 sequence also contains a yeast consensus ars of (t/a)tttatputtt(t/a). all of the maxicircles examined contained specific fragments that hybridized to the cf29 probe. ... | 1985 | 3938423 |
| sugar transport in trypanosoma brucei: a suitable kinetic probe. | a transport assay has been developed for use in the investigation of 1-deoxy-d-glucose uptake in trypanosomes. 1-deoxy-d-glucose has high affinity for the trypanosome sugar transport system (net influx km = 4.03 +/- 0.42 mm; v = 0.052 +/- 0.005 mm x s-1. d-glucose oxidation is competitively inhibited by 1-deoxy-d-glucose. however, we show that 1-deoxy-d-glucose is not a substrate for metabolism and that the competition occurs because of interaction at the transport system. d-glucose competitivel ... | 1986 | 3940883 |
| relapse infection after chemotherapy in goats experimentally infected with trypanosoma brucei: pathological changes in central nervous system. | fourteen goats were experimentally infected with trypanosoma brucei with the following results: four animals became terminally ill 24 to 47 days after inoculation of trypanosomes and were killed for necropsy. a second group of four goats became sick, had signs of systemic trypanosomiasis, were treated with diminazine aceturate (berenil) and recovered showing no signs of disease over observation periods of 151 to 163 days. a third group of six goats, were treated with berenil and temporarily reco ... | 1986 | 3946052 |
| the phospholipase a1 of trypanosoma brucei does not release myristate from the variant surface glycoprotein. | [3h]myristoyl-labeled variant surface glycoprotein (vsg) has been isolated from trypanosoma brucei by reverse phase high performance liquid chromatography and used as substrate for the conversion by trypanosomal enzymes of membrane-form vsg to soluble vsg. conversion is detected by the release of myristoyl-containing lipids. the major lipolytic enzyme of t. brucei, phospholipase a1, is effective for the hydrolysis of myristoyl esters of p-nitrophenol, in a colorimetric assay. however, the phosph ... | 1986 | 3949770 |
| lipid composition of bloodstream forms of trypanosoma brucei brucei. | the qualitative and quantitative lipid composition of bloodstream forms of trypanosoma brucei brucei s42 was compared with that of rat plasma and erythrocytes. the concentrations of lipid-bound phosphate and lipid-bound sialic acid in the trypanosomes were markedly higher than those of the rodent tissues. there was no trace in the trypanosomes of dolichol or dolichol phosphate. trypanosomes contained two unidentified lipids: an acidic phospholipid and a highly polar glycolipid. | 1986 | 3956175 |
| solution properties of the variant surface glycoprotein of trypanosoma brucei. | the solution properties of the membrane form and soluble form of variant surface glycoproteins from trypanosoma brucei have been compared. solution cross-linking studies established that both forms are dimers, although dissociation of membrane-form variant surface glycoprotein can be promoted by certain ionic and zwitterionic detergents. sedimentation coefficients were measured under a range of conditions, and the results were comparable with the results of solution cross-linking. stokes radii w ... | 1986 | 3960052 |
| conservation of kinetoplastid minicircle characteristics without nucleotide sequence conservation. | the nucleotide sequence and restriction fragment electrophoretic mobility of four minicircles from the kinetoplast dna of trypanosoma brucei were determined. each minicircle possesses an approximately 130 base pair conserved sequence which occurs in other african trypanosome minicircles and contains a 13 base pair sequence that is conserved among kinetoplastid genera [kidane et al. (1984) gene 27, 265-277]. a sequence located adjacent to the conserved sequence conserves purine versus pyrimidine ... | 1986 | 3960054 |
| sequence organization in african trypanosome minicircles is defined by 18 base pair inverted repeats. | we have found that minicircles of african trypanosomes contain 18 base pair sequences that occur as 3 or 4 pairs of imperfect inverted repeats. the 18 base pair sequence is polar; one half is almost perfectly conserved, while the other half has a more variable sequence. the distribution of the 18 base pair sequences in minicircles defines two classes of sequences ('a' and 'b' segments) that have distinct characteristics. 'a' segments vary considerably in length and contain about 10% more g+c tha ... | 1986 | 3960057 |
| the use of dna hybridization and numerical taxonomy in determining relationships between trypanosoma brucei stocks and subspecies. | the nuclear dnas of 71 trypanosome stocks from different african countries, representative of the three trypanosoma brucei subspecies, and one t. evansi stock, have been analysed by the combined use of restriction endonuclease digestion, gel electrophoresis and molecular hybridization with both trypanosome surface-antigen-specific and undefined genomic dna probes. in contrast with t. brucei brucei and t. brucei rhodesiense stocks, all the t. b. gambiense stocks are characterized by a conserved, ... | 1986 | 3960593 |
| independent expression of the metacyclic and bloodstream variable antigen repertoires of trypanosoma brucei rhodesiense. | the variable antigen repertoire expressed by metacyclic trypanosoma brucei rhodesiense is not influenced by the anamnestic expression whereby the variable antigen type (vat) ingested by a tsetse fly is present at high levels in early bloodstream populations of fly-infected mice. this has been demonstrated by feeding to glossina morsitans a trypanosome line expressing a vat which is normally a component of the metacyclic repertoire. the vat did not constitute a significantly increased proportion ... | 1986 | 3960594 |
| biosynthesis and processing of a variant surface glycoprotein from trypanosoma brucei brucei. | iowa trypanosome antigen type (iatat) 1.2 variant surface glycoprotein (vsg) is synthesized in vitro as a mr 54,000 preprotein that contains a 31-amino-acid signal peptide. translation of mrna in the presence of either dog pancreas or trypanosome microsomal membranes results in cotranslational cleavage of the signal peptide and addition of core oligosaccharide side chains to the protein. analysis of these products on sodium dodecyl sulfate (sds)-gels indicates that removal of the signal peptide ... | 1986 | 3963830 |
| the aerobic/anaerobic transition of glucose metabolism in trypanosoma brucei. | the ratio of glycerol to pyruvate produced by t. brucei incubated with glucose at various oxygen tensions has been used as an index of the aerobic and anaerobic pathways of glucose metabolism. a minimal model is presented which fits the observed data. the value of the notional k of the aerobic/anaerobic transition from the model is close to that of the km of trypanosomal glycerophosphate oxidase. the anaerobic pathway appears to be almost completely inoperative at oxygen tensions in the range of ... | 1985 | 3972106 |
| neutralization of individual variable antigen types in metacyclic populations of trypanosoma brucei does not prevent their subsequent expression in mice. | the trypanosoma brucei metacyclic population in the salivary glands of the tsetse fly displays a characteristic set of variable antigen types (vats) which represents only a restricted part of the parasite's total vat repertoire. after introduction into the mammalian host by fly bite, the metacyclics transform into bloodstream forms which retain expression of the metacyclic vats. specific antibodies, both polyvalent and monoclonal, have been used to neutralize separately 4 individual vats from me ... | 1985 | 3982856 |
| inosine analogs as chemotherapeutic agents for african trypanosomes: metabolism in trypanosomes and efficacy in tissue culture. | certain purine analogs, the pyrazolopyrimidines, are effective chemotherapeutic agents against leishmania spp. and trypanosoma cruzi both in vitro and in some clinical models. heretofore they have not been effective against the african trypanosomes; this suggested that these organisms were not comparable to the other pathogens with respect to their purine metabolism. we have studied the efficacy and metabolism of the pyrazolopyrimidine bases allopurinol and thiopurinol, their respective ribonucl ... | 1985 | 3985595 |
| trypanosoma brucei variant surface glycoprotein has a sn-1,2-dimyristyl glycerol membrane anchor at its cooh terminus. | the membrane form of trypanosoma brucei variant surface glycoprotein (mfvsg) is acylated with ester-linked tetradecanoic (myristic) acid (ferguson, m. a. j., and cross, g. a. m. (1984) j. biol. chem. 259, 3011-3015). comparative analysis of pronase peptides from mfvsg and soluble vsg localizes the site of mfvsg acylation to a cooh-terminal oligosaccharide structure. chemical and enzymatic treatment of the acylated pronase mfvsg fragment revealed that the myristic acid is present as a diglyceride ... | 1985 | 3988741 |
| release of the variable surface coat glycoprotein from trypanosoma brucei requires the cleavage of a phosphate ester. | the membrane-bound and released forms of the variant surface coat glycoprotein from trypanosoma brucei have been purified to homogeneity by a new rapid method in the absence of detergents. the conversion of the membrane-bound form to the released form has been found to consist of the cleavage of a phosphodiester bond, distal to the phosphate, linking the protein to a phospholipid. we suggest that this linkage constitutes the normal mode of attachment of the protein to the outer leaflet of the pl ... | 1985 | 3988749 |
| simultaneous isolation of cytoplasmic endoribonuclease and exoribonuclease of trypanosoma brucei. | an endoribonuclease and an exoribonuclease have been isolated simultaneously from the cytoplasm of trypanosoma brucei by hydroxyapatite column chromatography. the endoribonuclease produced oligonucleotides from poly(adenylic acid) with 5'-phosphate and 3'-oh termini. the exoribonuclease produced only ribonucleoside 5'-phosphates from poly(adenylic acid). the relative rates of degradation of synthetic homopolynucleotides by the endoribonuclease under standard conditions were in the order poly(ade ... | 1985 | 3990709 |
| induction of human serum-sensitive trypanosoma brucei stabilates into human serum-resistant "t. rhodesiense". | when chronic trypanosoma brucei infections of mice are treated with 20 mg/kg suramin, those trypanosomes which have escaped chemotherapy because they are residing in the brain, exhibit a higher degree of human serum resistance than the original infection. this resistance increases if the chronic infection is retreated for a second time, before the trypanosomes in the brain are tested by the blood incubation infectivity test. the transformation is not due to a selection of t. rhodesiense from a t ... | 1985 | 3992646 |
| structure and variation within variant surface glycoproteins of trypanosoma brucei. | variant surface glycoproteins of the african trypanosomes are members of a multigene family which show extraordinary amino sequence diversity. the extent of this diversity and the significance of homologies both in the amino acid sequence and in the post-translational modifications are discussed in the light of what is predicted for the structure of these molecules and what is now known from x-ray crystallographic analysis. | 1985 | 3994303 |
| cross-linking of the enzymes in the glycosome of trypanosoma brucei. | glycosomes, the microbody-like organelles containing mainly glycolytic enzymes, were purified from the long slender bloodstream form of trypanosoma brucei eatro 110 monomorphic strain by an improved method in which the protozoa were frozen and thawed in 15% glycerol to free, from the plasma membrane, much of the variant surface glycoprotein which used to constitute the major contaminant of our purified glycosomes. the purified glycosomes have 11 major proteins, 6 of which, tentatively identified ... | 1985 | 3997856 |
| interactions between trypanosoma brucei and babesia spp. and plasmodium spp. in mice. | swiss mice with chronic trypanosoma brucei infections become refractory to subsequent infection with babesia microti and b. rodhaini. infection with b. microti 7 days after t. brucei resulted in an obvious inhibition of the babesia parasitaemias and this inhibition became more profound as the time interval between the infections increased, until at 17-20 days the parasitaemias were totally abolished. even after intravenous injection of large numbers of parasites parasitaemias were inhibited. sim ... | 1985 | 4000702 |
| cultivation in a semi-defined medium of animal infective forms of trypanosoma brucei, t. equiperdum, t. evansi, t. rhodesiense and t. gambiense. | a semi-defined medium for the cultivation of bloodstream forms of the african trypanosome brucei subgroup was developed. out of 14 different strains tested, 10 could be cultured including trypanosoma brucei, t. equiperdum, t. evansi, t. rhodesiense and t. gambiense. the presence of a reducing agent (2-mercaptoethanol or thioglycerol) was found to be essential for growth. the standard medium consisted of hepes buffered minimum essential medium with earle's salts supplemented with 0.2 mm 2-mercapt ... | 1985 | 4006919 |
| the solubilization of a sham sensitive, cyanide insensitive ubiquinol oxidase from trypanosoma brucei. | | 1985 | 4009352 |
| trypanosome variant surface glycoprotein genes expressed early in infection. | we have studied further the genes for trypanosomal variant surface glycoproteins expressed during a chronic infection of rabbits with trypanosoma brucei, strain 427. we show that there are three closely related chromosomal-internal isogenes for vsg 121; expression of one of these genes is accompanied by the duplicate transposition of the gene to a telomeric expression site, also used by other chromosome-internal vsg genes. the 3' end of the 121 gene is replaced during transposition with another ... | 1985 | 4009712 |
| maternally derived immunity in young mice to infection with trypanosoma brucei and its potentiation by berenil chemotherapy. | young mice which were allowed to suckle, from birth, a mother infected with trypanosoma brucei, or a mother whose infection had been cured before parturition with berenil chemotherapy, were themselves immune to homologous trypanosome challenge. this immunity extended until approximately 25 days of age, and was transmitted in the colostrum/milk of the mother. mice born of infected mothers, but transferred at birth to normal foster mothers, were susceptible to trypanosome infection. drug prophylax ... | 1985 | 4011302 |
| the 5.8s ribosomal rna gene of trypanosoma brucei: structural and transcriptional studies. | to further investigate the process of discontinuous transcription in trypanosomes, the 5.8s rrna gene, present in the trypanosome genome as part of the multicopy rrna gene cluster, has been cloned, sequenced, chromosomally mapped, and used in transcriptional studies. the gene's sequence confirms its identity and indicates that it is less conserved evolutionarily than the trypanosome 5s rrna gene previously described by our laboratory (6). examination of the chromosomal locations of the gene by p ... | 1985 | 4011434 |
| heat shock genes: regulatory role for differentiation in parasitic protozoa. | the parasitic protozoa trypanosoma brucei and leishmania major are transmitted by insect vectors to their mammalian hosts. the temperature difference between the hosts (25 degrees and 37 degrees c) may induce a heat shock response in the parasite. transcripts of heat shock genes (homologous to hsp70 and hsp83) were 25 to 100 times more abundant in trypanosoma brucei bloodstream forms (trypomastigotes) than in insect (procyclic) stages. in leishmania major the patterns of heat shock gene expressi ... | 1985 | 4012301 |