| the topogenic signal of the glycosomal (microbody) phosphoglycerate kinase of crithidia fasciculata resides in a carboxy-terminal extension. | to determine how microbody proteins enter microbodies, we have previously compared the genes for the cytosolic and glycosomal (microbody) phosphoglycerate kinases (pgks) of trypanosoma brucei and found the microbody enzyme to differ from other pgks and the cytosolic form in two respects: a high net positive charge and a c-terminal extension of 20 amino acids (osinga et al., 1985). here we present the comparison of the genes for the cytosolic and glycosomal pgks of crithidia fasciculata, another ... | 1988 | 3402434 |
| putative genes of a variant-specific antigen gene transcription unit in trypanosoma brucei. | in a 7-kilobase (kb) sequence upstream from the 5' barren region, the trypanosoma brucei antat 1.3a expression site carries two putative genes, named esag 2 and esag 3 for expression site-associated genes, as well as a copy of esag 1 (d.f. cully, h.s. ip, and g.a.m. cross, cell 42:173-182, 1985). at least 3 kb of this expression site exhibits a high degree of homology with the silent telomere carrying the antat 1.3a basic copy, whose esag 1 is interrupted by stop codons. like the antigen gene, t ... | 1988 | 3405209 |
| trypanosome trans-splicing utilizes 2'-5' branches and a corresponding debranching activity. | the 5' ends of trypanosome mrnas consist of an identical sequence of 39 nucleotides which is derived from a discrete transcript of approximately 140 nucleotides (medrna). it has been proposed that generation of chimeric mrnas in trypanosomes occurs by the process of trans-splicing involving medrna and an acceptor rna. part of the basis for this suggestion comes from the ability of hela cell extracts (known to contain debranching activity) to catalyze the release of the intron portion of medrna ( ... | 1988 | 3409870 |
| detection of a possible trans-splicing intermediate in trypanosoma brucei. | | 1988 | 3412901 |
| receptors for the host low density lipoproteins on the hemoflagellate trypanosoma brucei: purification and involvement in the growth of the parasite. | the slender bloodstream form of trypanosoma brucei shows receptor-mediated endocytosis of low density lipoprotein (ldl) particles of its hosts. we have purified the ldl receptor of this species nearly to homogeneity (about 1000-fold purification) and obtained monospecific polyclonal antibodies against it. as analyzed by nadodso4/polyacrylamide gel electrophoresis, the purified receptor consists of a single subunit, with an apparent molecular mass of 86 kda. its isoelectric point is 5.9. on the a ... | 1988 | 3413122 |
| a 60-kda cytoskeletal protein from trypanosoma brucei brucei can interact with membranes and with microtubules. | the cytoskeleton of eukaryotic cells is a major determinant of cellular architecture and of many cellular functions. in addition to or in place of the transcellular cytoskeleton, many eukaryotic cells also contain membrane-associated cytoskeletal structures (membrane skeletons), which are important for cellular structure and function. the membrane skeleton of the parasitic hemoflagellate trypanosoma brucei consists of a dense array of singlet microtubules (subpellicular microtubules), which are ... | 1988 | 3422481 |
| [conventional and analytic morphometry using the ibas-1 computer in experimental trypanosoma b. brucei infection]. | a comparative morphometrical study of the experimental infection with t. b. brucei was realized using the conventional method and the ibas-1 analytic computer. the studied strain of t. b. brucei was preserved during 10 years in laboratory conditions, through inoculations from mice to mice. the effect of a low dose of suramin upon the percentage of different morphological forms of the parasite was analysed and compared with the untreated lots. certain differences could be appreciated in the resul ... | 1987 | 3426075 |
| identification of a developmentally regulated calcium-binding protein in trypanosoma brucei. | calcium ions mediate cellular activity by binding to specific cellular proteins. the following study systematically examines the cellular complement of calcium-binding proteins in different cell fractions and life cycle stages of trypanosoma brucei. using a 45ca-gel overlay procedure, eight calcium-binding proteins were consistently observed. the majority of proteins were cytosolic (84, 70, 64, 22, and 15 kd) while the remainder (55, 46, and 29 kd) were particulate. although calmodulin was detec ... | 1987 | 3430408 |
| structure determination of the glycosomal triosephosphate isomerase from trypanosoma brucei brucei at 2.4 a resolution. | the three-dimensional crystal structure of the enzyme triosephosphate isomerase from the unicellular tropical blood parasite trypanosoma brucei brucei has been determined at 2.4 a resolution. this triosephosphate isomerase is sequestered in the glycosome, a unique trypanosomal microbody of vital importance for the energy-generating machinery of the trypanosome. the crystals contain one dimer per asymmetric unit. the structure could be solved by the method of molecular replacement, using the refi ... | 1987 | 3430602 |
| flow cytofluorimetric analysis of drug accumulation by multidrug-resistant trypanosoma brucei brucei and t. b. rhodesiense. | dual laser flow cytofluorimetry has been used to compare accumulation of compounds representing three major classes of trypanocidal drugs by drug sensitive and drug resistant clones of trypanosoma brucei brucei and t. b. rhodesiense. clones selected for resistance to melarsoprol were shown to be cross-resistant in vivo to two diamidines, pentamidine and berenil, but not to suramin. at 35 degrees c, bloodstream forms of these multidrug-resistant clones accumulated lower intracellular concentratio ... | 1987 | 3431564 |
| the genome and the antigen gene repertoire of trypanosoma brucei gambiense are smaller than those of t. b. brucei. | the amount of nuclear dna of trypanosoma brucei gambiense is only 70% of that of t. b. brucei. the difference is partially due to depletion of 50-150 kb mini-chromosomes in t. b. gambiense, as well as a reduction in the content of some repetitive dna families. quantitation of 'barren' dna regions characteristic of the 5' environment of telomeric antigen genes confirms that the t. b. gambiense genome contains fewer chromosome ends, and thus most probably fewer telomeric antigen genes, than t. b. ... | 1987 | 3431572 |
| macrophage procoagulant activity in experimental african trypanosomiasis. | peritoneal macrophages from mice infected with trypanosoma brucei brucei expressed a greatly elevated procoagulant activity (pca) which could be reversed to normal levels after trypanocidal therapy. comparison with infection caused by the non-pathogenic t. musculi suggested that the level of pca related to parasite pathogenicity. unstimulated macrophages, which generate only slight pca upon stimulation with zymosan, become hyperresponsive to this stimulus during the course of infection. hyperres ... | 1987 | 3431901 |
| lectin mediated establishment of midgut infections of trypanosoma congolense and trypanosoma brucei in glossina morsitans. | d+glucosamine, which has been shown in vitro to specifically inhibit tsetse midgut lectin activity, when fed to glossina morsitans morsitans with the infective feed significantly increased midgut infection rates of trypanosoma congolense and t. brucei rhodesiense. all flies infected with t.b. rhodesiense and maintained on a diet of blood with d+glucosamine throughout their lives developed midgut infections. midgut extracts from flies bred for refractoriness to infection with trypanosomes showed ... | 1987 | 3432950 |
| trypanocidal activity of a 5-substituted 2-nitroimidazole compound (ro 15-0216) in mice. | the trypanocidal activity of a 5-substituted 2-nitroimidazole compound (ro 15-0216, 2-(dimethylamino)-4'-[(1-methyl-2-nitroimidazole-5-yl) methoxy] acetanilid) was tested in stocks of t.b. brucei, t.b. evansi, t. vivax, and t. congolense. the trypanosome stocks showed different sensitivities, the trypanozoon group was most sensitive followed by t. vivax and t. congolense. administration of the compound in the drinking water was superior to single intraperitoneal injections. a t.b. brucei stock w ... | 1987 | 3432951 |
| reticulocytes in peripheral blood of mice infected with trypanosoma brucei: dramatic decrease of reticulocytes during primary wave of parasitemia. | infection of mice with rapidly proliferating trypanosomes that killed the mice in the first or second wave of parasitemia led to a dramatic decrease of immature erythrocytes in the peripheral blood during the primary wave of parasitemia. trypanosome variants producing lower first waves of parasitemia, and/or less rapid deaths, caused a variable, on the average small, decrease of immature erythrocytes. trypanosome variants causing rapidly lethal infections killed the mice before a decrease of imm ... | 1987 | 3441739 |
| chemotherapy of late-stage trypanosomiasis: the effect of the nitrothiazole compounds. | | 1987 | 3445346 |
| a simple in vitro method for infecting tsetse with trypanosomes. | | 1987 | 3446032 |
| an acridine-linked oligodeoxynucleotide targeted to the common 5' end of trypanosome mrnas kills cultured parasites. | anti-messenger oligodeoxynucleotides covalently linked to an intercalating agent were tested for their ability to inhibit translation of trypanosoma brucei mrnas in a cell-free system. the sequence of these oligodeoxynucleotides was complementary to part of the 35-nucleotide (nt) sequence which is present at the 5' end of all trypanosome mrnas (the so-called mini-exon sequence). in a rabbit reticulocyte lysate, a nonadeoxynucleotide linked to an acridine derivative, specifically inhibited protei ... | 1987 | 3446576 |
| [trypanocidal activity of isoquinoline alkaloids in mice]. | | 1987 | 3455659 |
| leishmania and trypanosoma surface glycoproteins have a common glycophospholipid membrane anchor. | the variant surface glycoprotein (vsg) of the african trypanosomes is the major membrane protein of the plasma membrane of the bloodstream stage of the parasite. it is anchored in the plasma membrane by a glycolipid covalently bound to the c-terminal amino acid of the protein. the vsg is released through the action of a phosphatidylinositol-specific phospholipase c that removes dimyristoylglycerol and exposes the carbohydrate antigenic determinant common to all vsgs. promastigotes of leishmania ... | 1986 | 3461472 |
| evidence for haploidy in metacyclic forms of trypanosoma brucei. | the parasitic flagellate trypanosoma brucei undergoes a series of morphologic and metabolic changes during its passage in the digestive organs of its insect vector, a glossina or tsetse fly. this morphogenesis ends by the differentiation, in the salivary gland of the fly, of the metacyclic form, which will be transmitted in the bloodstream of the mammalian host. on the basis of dna microfluorometric measurements, we propose that these metacyclic trypanosomes have a haploid amount of dna, compare ... | 1986 | 3461475 |
| tubulin isotypes: generation of diversity in cells and microtubular organelles. | diversity of tubulin isotypes is illustrated by consideration of the beta-tubulin isotypes of higher plants and the eukaryotic microbe, physarum polycephalum, and by the alpha-tubulin isotypes of the protozoan, trypanosoma brucei. the carrot plant expresses six, well-defined beta-tubulin isotypes that possess characteristic two-dimensional gel coordinates. these six beta-tubulin isotypes are differentially expressed during development of the flowering plant. in a similar manner, physarum express ... | 1986 | 3477554 |
| efficient introduction of plasmid dna into trypanosoma brucei and transcription of a transfected chimeric gene. | electroporation induces efficient transient transfection of trypanosoma brucei, and the introduced dna can be transcribed into rna. when we delivered a high-voltage electric pulse to cells mixed with radiolabeled pbr322, approximately equal to 15% of the plasmid dna was taken up by the parasites. when transfecting dna contained a segment of t. brucei ribosomal dna that included the 5' end of the rrna gene, the introduced plasmid directed expression of rna; this rna expression was shown both by d ... | 1987 | 3479766 |
| use of symptoms and signs for diagnosis of trypanosoma brucei rhodesiense trypanosomiasis by rural health personnel. | the results are described of a study of 60 patients with sleeping sickness from north-east zambia together with 60 hospital controls and 27 nearest-neighbour controls. eight symptoms were significantly commoner among sleeping-sickness patients than among either set of controls, and some of these symptoms were used to devise a scoring system for use by rural medical personnel. although most patients reported a short history of the illness, almost 90% had abnormal cerebrospinal fluid, and there wa ... | 1986 | 3490318 |
| analysis of b cell and t cell proliferative responses induced by monomorphic and pleomorphic trypanosoma brucei parasites in mice. | cells collected from c57b1/6 mice infected with monomorphic and pleomorphic clones of trypanosoma brucei parasites (iltat 1.4 and gutat 3.1) were analysed for the incorporation of 125i-iododeoxyuridine into dna of total splenic lymphocytes and of b and t lymphocytes isolated on a fluorescence activated cell sorter. the monomorphic t. brucei iltat 1.4 parasites triggered delayed and low splenic dna synthetic responses in comparison to those arising in mice infected with the pleomorphic t. brucei ... | 1986 | 3490650 |
| expression of the b cell repertoire and autoantibodies in human african trypanosomiasis. | the relative importance of polyclonal b cell activation has been studied in relation to the development of autoantibodies in human african trypanosomiasis. in 34 patients investigated before specific treatment a broad expression of the b cell repertoire was observed including the production of anti-hapten (fitc, penicillin, phosphorylcholin) antibodies, of high levels of antibodies against some heterologous protein antigens (ovalbumin and tetanus toxoid) and of autoantibodies. anti-ssdna antibod ... | 1986 | 3491699 |
| t-lymphocyte requirement for the induction of mouse macrophage procoagulant activity by trypanosoma brucei. | we have previously shown that peritoneal macrophages from trypanosoma brucei infected mice, but not from uninfected mice, expressed high levels of procoagulant activity that could not be produced in vitro by incubation of unstimulated macrophages with bloodstream forms of trypanosomes. in the present study we demonstrate that trypanosome-induced macrophage activation can be achieved in vitro by providing either sensitized (day 7 of infection) lymphocytes and trypanosomes or the supernatant fluid ... | 1987 | 3501564 |
| phenothiazines in murine african trypanosomiasis. | | 1987 | 3503414 |
| thiol-dependent proteases of african trypanosomes. analysis by electrophoresis in sodium dodecyl sulphate/polyacrylamide gels co-polymerized with fibrinogen. | the proteases of several species of african trypanosomes were analysed by electrophoresis in sodium dodecyl sulphate/polyacrylamide gels containing fibrinogen or collagen. after electrophoresis the gels were incubated in the presence of enzyme activators and/or inhibitors and then stained with coomassie brilliant blue. the areas where the proteolytic activity had degraded the fibrinogen did not stain and so formed clear bands against a blue background. the proteases were found to have ph optima ... | 1986 | 3514210 |
| the occurrence and distribution of alpha-hydroxy-acid dehydrogenase in some members of the order kinetoplastida. | ldh-x is the isoenzyme of lactate dehydrogenase found in mammalian spermatozoa, occurring in cytosolic and mitochondrial locations. gossypol strongly inhibits it, and the spermicidal action of this compound is attributed to the disruption of a reducing shuttle. the flagellated protozoan, trypanosoma cruzi, contains an enzyme activity similar to ldh-x, called alpha-hydroxy-acid dehydrogenase, which is here shown to possess cytosolic and glycosomal components. the glycosome is a microbody-like org ... | 1986 | 3516722 |
| analysis of antigen switching rates in trypanosoma brucei. | previously quoted figures for the frequency of antigen switching in trypanosoma brucei are based on incorrect assumptions. in order to determine the correct switching frequency, an equation was derived that takes the growth rates of the newly expressed antigen types into consideration as well as the proportion of switched trypanosomes and the number of generations since the population was antigenically homogeneous. when this equation was applied to published in vitro data, variable values were o ... | 1986 | 3520447 |
| the 35-nucleotide spliced leader sequence is common to all trypanosome messenger rna's. | in trypanosomatidae the messenger rna's (mrna's) that code for the variant surface glycoproteins (vsg's), tubulins, calmodulin, and at least a subset of other proteins contain a common 35-nucleotide leader sequence at their 5' ends. hybrid-arrested in vitro translation has been used to show that all mrna's in both african and south american trypanosomes contain this 35-nucleotide sequence. oligonucleotides complementary to this sequence blocked translation of all trypanosome mrna's in a rabbit r ... | 1986 | 3523758 |
| evolutionary conservation of the substrate-binding cleft of phosphoglycerate kinases. | the primary structures of six phosphoglycerate kinases (pgks) are known: three from mammals, one from yeast, and two from trypanosomes. comparison of the amino acid sequence of these enzymes reveals 154 invariant positions out of 392 positions in the aligned sequences. most of the conserved positions fall into the twelve beta-sheets and adjacent peptide regions that form the inner loops surrounding the atp and 3-phosphoglycerate-binding cleft. the homology between mammalian and yeast pgks is gre ... | 1986 | 3525226 |
| a study of the membrane attachment site of the membrane-form variant surface glycoprotein from trypanosoma brucei brucei using lipid vesicles as a model of the plasma membrane. | the incorporation of the membrane form and the soluble form of variant surface glycoprotein (mfvsg and svsg) from trypanosoma brucei brucei into liposomes has been investigated. it was found that selective incorporation of mfvsg into liposomes was possible in the presence of 8 m urea as a denaturing agent; svsg, by contrast, was incorporated only poorly into liposomes. after proteolysis of mfvsg incorporated into liposomes, a compound was isolated from the liposomes which carries with it constit ... | 1986 | 3528849 |
| physical and immunological analysis of the two domains isolated from a variant surface glycoprotein of trypanosoma brucei. | a specific surface glycoprotein of a variant of trypanosoma brucei was cleaved with trypsin and the two major domains of the molecule have been purified. we have studied the chemical composition of each domain and compared the data to published results of the specific cdna sequence. circular dichroism measurements show that the amino-terminal domain includes preferentially alpha-helical or beta-sheet structure. the physicochemical analyses are supplemented by a prediction of secondary structure ... | 1986 | 3530134 |
| inhibitory action of the antitumor agent lonidamine on mitochondrial respiration of trypanosoma cruzi and t. brucei. | the antitumor and antispermatogenic agent lonidamine inhibits trypanosoma cruzi epimastigotes growth in culture with an id50 around 80 microm. the main site of action appears to be the mitochondria, where the rate of uncoupled respiration was inhibited in 50% at a similar lonidamine concentration (50 microm). hexokinase (the other point where lonidamine inhibits tumor energy metabolism) was not sensitive to this drug. lonidamine also inhibited uncoupled respiration in t. brucei procyclic trypoma ... | 1986 | 3531848 |
| a trypanosoma cruzi monoclonal antibody that recognizes a superficial tubulin-like antigen. | a monoclonal antibody (mab 10), obtained from mice infected with trypanosoma cruzi, was found to recognize a superficial antigen in living or fixed parasites. it reacted more strongly with t. cruzi than with related parasites such as t. brucei and leishmania. in immunoblots it recognized a single trypanosoma polypeptide and also brain tubulin, both of which had the same electrophoretic mobility. further analysis suggested that the alpha-tubulin subunit contained the epitope recognized by mab 10. ... | 1986 | 3533072 |
| [sleeping sickness from early diagnosis to post-therapy follow-up]. | | 1986 | 3533186 |
| identification of proteins encoded by variant surface glycoprotein expression site-associated genes in trypanosoma brucei. | the variant surface glycoprotein (vsg) genes of trypanosoma brucei may be transcribed from several distinct telomeric expression sites (ess). the mechanism responsible for regulating potential expression sites is unknown. two members of a pleomorphic family of expression site associated genes (esags) have been cloned and sequenced. by examination of the dna sequences we inferred that esags encode amphiphilic glycoproteins. fragments of two esags were inserted into the escherichia coli expression ... | 1986 | 3537782 |
| eukaryotic protein modification and membrane attachment via phosphatidylinositol. | | 1987 | 3542226 |
| distinct localization and cell cycle dependence of cooh terminally tyrosinolated alpha-tubulin in the microtubules of trypanosoma brucei brucei. | alpha-tubulin can be posttranslationally modified in that its cooh-terminal amino acid residue, tyrosine, can be selectively removed and replaced again. this reaction cycle involves two enzymes, tubulin carboxypeptidase and tubulin tyrosine ligase. the functional significance of this unusual modification is unclear. the present study demonstrates that posttranslational tyrosinolation of alpha-tubulin does occur in the parasitic hemoflagellate trypanosoma brucei brucei and that posttranslational ... | 1987 | 3546334 |
| the monogenetic kinetoplastid protozoan, crithidia fasciculata, contains a transcriptionally active, multicopy mini-exon sequence. | a repeated sequence from the crithidia fasciculata nuclear genome has been isolated which is homologous to the mini-exon genes of other kinetoplastid protozoa. sequence analysis of the 417 bp monomeric unit confirmed the presence of a 35 nt sequence within the repeat that is 77% homologous with the trypanosoma brucei 35-mer mini-exon or spliced leader sequence. the repeat is present at approximately 250 copies per cell and is organized into one, or a few, large head to tail tandem clusters predo ... | 1987 | 3562248 |
| developmentally regulated addition of nucleotides within apocytochrome b transcripts in trypanosoma brucei. | production of the mitochondrial respiratory system and expression of mitochondrial genes are developmentally regulated in t. brucei. we have found three classes of apocytochrome b (cyb) transcripts. two of these contain u's within their 5' sequence that are not found in the cyb gene. they occur in procyclic forms, which have a complete mitochondrial respiratory system, but are absent in bloodstream forms, which lack this respiratory system. the third transcript has the sequence predicted from th ... | 1987 | 3568129 |
| differential protein synthesis during the life cycle of the protozoan parasite trypanosoma brucei. | two-dimensional polyacrylamide gel electrophoresis has been used to analyze changes in protein content and protein synthesis in three stages of the life cycle of the protozoan parasite trypanosoma brucei. the stages examined were slender and stumpy mammalian bloodstream forms and procyclic forms, which are analogous to the tsetse fly midgut stage. two-dimensional gels of 35s-methionine-labeled proteins were examined by autoradiography to analyze newly synthesized protein, and gels were stained w ... | 1987 | 3572842 |
| an assay of membrane-bound trypanosoma brucei phospholipase using an integral membrane protein substrate and detergent phase separation. | the technique of phase separation in a solution of the non-ionic detergent triton x-114 was used to measure the enzymatic conversion of a membrane protein to a soluble product via removal of a hydrophobic moiety. the substrate was the major surface protein (p63), of leishmania promastigotes and the enzyme was a phospholipase c purified from trypanosoma brucei. this membrane-bound enzyme is responsible for the cleavage of the hydrophobic lipid membrane anchor of the variant surface glycoprotein ( ... | 1987 | 3574348 |
| characterization of genes coding for two major metacyclic surface antigens in trypanosoma brucei. | in african trypanosomes, only a very small fraction of the total repertoire of variable antigen types (vats) is expressed by the metacyclic form. in trypanosoma brucei stock eatro 1125, the vats antat 1.30 and 1.45 are reproducibly present in about 15% and 4% of the metacyclic population, respectively. the genes encoding the corresponding antigens or variant surface glycoproteins (vsgs) are in telomeres of large chromosomes, as are some non-metacyclic vsg genes from the same stock. their activat ... | 1987 | 3574351 |
| cytoskeleton. tubulin's terminal tyrosine. | | 1987 | 3574472 |
| the rate of proliferation among african trypanosomes is a stable trait that is directly related to virulence. | the relationship between the growth rate of trypanosoma brucei gambiense and its virulence was investigated. a cloned, monomorphic, slow growing, and relatively avirulent line of t. b. gambiense was serially passaged at 3- to 5-day intervals through immunosuppressed mice. the growth rate measured within the first 2 patent days of infection did not vary significantly through the first 25 passages but by passage 50 had decreased significantly from 11.9 +/- 1.1 hr to 9.0 +/- 0.7 hr. a clone from pa ... | 1987 | 3578651 |
| heterogeneity in high performance liquid chromatography of a variant surface glycoprotein of trypanosoma brucei. | high performance liquid chromatography (hplc) procedures have been used to analyze a preparation of the variant surface glycoprotein antat 1.1a of trypanosoma brucei. the native preparation gives several peaks with a high reproducibility both by reverse-phase (rp-) and gel permeation (gp-) hplc. under rp-hplc conditions, nine fractions are fully resolved. the rp-hplc fractions migrate with the same molecular weight vsg band on polyacrylamide slab gel electrophoresis and no significant difference ... | 1987 | 3579956 |
| common elements on the surface of glycolytic enzymes from trypanosoma brucei may serve as topogenic signals for import into glycosomes. | in trypanosoma brucei, a major pathogenic protozoan parasite of central africa, a number of glycolytic enzymes present in the cytosol of other organisms are uniquely segregated in a microbody-like organelle, the glycosome, which they are believed to reach post-translationally after being synthesized by free ribosomes in the cytosol. in a search for possible topogenic signals responsible for import into glycosomes we have compared the amino acid sequences of four glycosomal enzymes: triosephospha ... | 1987 | 3582360 |
| human serum resistance of metacyclic forms of trypanosoma brucei brucei, t. brucei rhodesiense and t. brucei gambiense. | resistance against the lytic action of human serum has been tested among metacyclic and bloodstream forms of trypanosoma brucei brucei, t.b. rhodesiense and t.b. gambiense stocks and clones. the resistance was determined by applying an in vitro human serum resistance test. whereas the majority of t.b. gambiense metacyclic forms exhibited stable human serum resistance, t.b. rhodesiense metacyclics showed inconsistent resistance within a minority of parasites, which tended to diminish completely w ... | 1987 | 3588581 |
| demonstration of rna polymerase multiplicity in trypanosoma brucei. characterization and purification of alpha-amanitin-resistant and -sensitive enzymes. | we have isolated, characterized and substantially purified two distinct rna polymerase activities from the flagellate protozoan parasite trypanosoma brucei. rna polymerases from this organism were resolved poorly on deae-sephadex, but could be separated with cm-sephadex. one form was totally resistant to alpha-amanitin, whereas the second was 50% inhibited by 10-20 micrograms of the drug/ml. the enzymes had different salt optima, but both were of high mr (greater than 480,000) and demonstrated t ... | 1987 | 3593214 |
| regulation of mitochondrial gene expression in trypanosoma brucei. | | 1987 | 3593329 |
| in vivo labelling of intermediates in the discontinuous synthesis of mrnas in trypanosoma brucei. | discontinuous mrna synthesis in trypanosomes is thought to involve a 140-nucleotide precursor, called the mini-exon-derived rna or medrna, which contributes its 5' 35 nucleotides to the 5' end of nascent mrnas. we used in vivo labelling of rna to show that medrna has a half-life of less than 6 min, whereas putative high mol. wt intermediates containing the 3' part of the medrna have an average half-life of less than 1 min. this eliminates priming of pre-mrna synthesis by intact medrna as the mai ... | 1987 | 3595556 |
| evidence of blood cerebrospinal fluid barrier permeability impairment in chronic trypanosoma rhodesiense infection in a vervet monkey. | | 1986 | 3603626 |
| failure of berenil therapy to eliminate early infections with a strain of trypanosoma brucei from west abaya, ethiopia. | | 1987 | 3603714 |
| biogenesis of the glycosome in trypanosoma brucei: the synthesis, translocation and turnover of glycosomal polypeptides. | glycosomes, the microbodies of trypanosoma brucei, contain a number of enzymes involved in glucose and glycerol metabolism. the biogenesis of three of these enzymes has been studied. aldolase, d-glyceraldehyde-3-phosphate dehydrogenase and nad-linked glycerol-3-phosphate dehydrogenase are all synthesized in the cytosol on free rather than on membrane-bound polysomes. in vitro, as well as in vivo, these polypeptides are synthesized at their mature size, and no evidence was found for any processin ... | 1987 | 3608983 |
| trypanosoma rhodesiense: antigenicity and immunogenicity of flagellar pocket membrane components. | a low density membrane fraction, isolated from the bloodstream stage of trypanosoma rhodesiense and enriched in flagellar pocket membrane, was characterized with regard to antigenicity using antibodies raised against purified flagellar pocket membrane. mild trypsinolysis of flagellar pocket membrane released two small peptides (mr = 13-16 x 10(3)) separated by chromatofocusing (pi = 6.8 and 5.8) that were antigenic as monitored by fused rocket immunoelectrophoresis. both of these antigenic pepti ... | 1987 | 3609224 |
| coincident multiple activations of the same surface antigen gene in trypanosoma brucei. | trypanosomes with a coat of variant surface glycoprotein (vsg) 118, consistently appear around day 20 when a rabbit is infected with trypanosoma brucei strain 427. there is a single chromosome-internal gene for vsg 118 and this is activated by duplicative transposition to a telomeric expression site. we show here that the expression-linked extra copy of vsg gene 118 in a day 18 population of a chronic infection is heterogeneous, and we infer that the population is not monoclonal but is the resul ... | 1987 | 3612801 |
| trypanothione dependent peroxide metabolism in crithidia fasciculata and trypanosoma brucei. | a trypanothione-dependent peroxidase activity has been identified in the insect trypanosomatid crithidia fasciculata and in the mammalian trypanosome trypanosoma brucei. using organic hydroperoxides as oxidant, specific peroxidase activities in these organisms are 5.0 and 1.0 nmol min-1 (10(8) cells)-1 respectively. the t. brucei peroxidase had an activity of 0.4 nmol min-1 (10(8) cells)-1 using hydrogen peroxide as oxidant. the enzyme is specific for the n1,n8-bis(glutathionyl)spermidine conjug ... | 1987 | 3614271 |
| melarsoprol and reactive encephalopathy in trypanosoma brucei rhodesiense. | | 1987 | 3617176 |
| secondary structure of the variant surface glycoproteins of trypanosomes. | the secondary structure of seven variant surface glycoproteins (vsgs) of trypanosomes has been determined by raman spectroscopy. they are all predominantly alpha-helical, the alpha-helix content varying between 50 and 60%. the beta-strand content varies between 20 and 25%, and the content of beta-turn and nonregular structures is about 25%. for three vsgs the n-terminal domain obtained by proteolytic cleavage was found to have essentially the same secondary structure as the complete vsgs. for th ... | 1987 | 3622761 |
| subcellular localization of a variable surface glycoprotein phosphatidylinositol-specific phospholipase-c in african trypanosomes. | african trypanosomes contain a membrane-bound enzyme capable of removing dimyristylglycerol from the membrane-attached form of the variable surface glycoprotein (mfvsg; ferguson, m. a. j., k. halder, and g. a. m. cross, 1985, j. biol chem., 260:4963-4968). although mfvsg phospholipase-c has been implicated in the removal of the vsg from the trypanosome surface (cardoso de almeida, m. l., and m. j. turner, 1983, nature (lond.)., 302:349-352; ferguson, m. a. j., k. halder, and g. a. m. cross, 1985 ... | 1987 | 3624307 |
| the role of antibody in african trypanosomiasis. | | 1987 | 3625434 |
| preliminary crystallographic studies of glycosomal glyceraldehyde phosphate dehydrogenase from trypanosoma brucei brucei. | crystals of glyceraldehyde phosphate dehydrogenase from the glycosome of trypanosoma brucei brucei have been grown, and a partial data set has been collected using synchrotron radiation. the crystals diffract initially to 2.3 a resolution. the space group is p2(1)2(1)2, with cell dimensions a = 135 a, b = 255 a, c = 115 a, so there are probably at least two tetramers in the asymmetric unit. | 1987 | 3625777 |
| onset of expression of the variant surface glycoproteins of trypanosoma brucei in the tsetse fly studied using immunoelectron microscopy. | the acquisition of the variant surface glycoprotein (variable antigen) coat by metacyclic stage trypanosoma brucei in the salivary glands of the tsetse fly, glossina morsitans, has been studied in situ by transmission and scanning electron microscopy using monoclonal antibodies raised against metacyclic variable antigen types and complexed with horseradish peroxidase or colloidal gold. the coat is acquired after binary fission has ceased but while the parasite is still attached to the gland epit ... | 1987 | 3654788 |
| trypanosoma brucei repeated element with unusual structural and transcriptional properties. | the genome of trypanosoma brucei contains up to 400 copies of a conserved sequence (trs, trypanosome repeated sequence). the majority of trs copies (trs1) are 5.2 x 10(3) base-pairs (kb) and are flanked by different separate halves of the previously described transposable element rime (ribosomal mobile element), although a variant copy (trs2) contains only the central 1.45 kb portion and lacks rime. trs1 elements can probably undergo transposition, since they are dispersed in all chromosome size ... | 1987 | 3656436 |
| precise identification of cleavage sites involved in the unusual processing of trypanosome ribosomal rna. | the large subunit ribosomal rna (lsrna) of trypanosoma brucei is unusual in being cleaved at multiple sites to yield six stable fragments of rna. we report here the complete nucleotide sequence of two regions of the ribosomal dna repeat unit. the first sequence includes all of the processing sites involved in the generation of one of the small lsrna fragments. the second region encodes the trypanosome 5.8 s rna. by rna sequencing and s1 nuclease mapping, we have identified the processing sites i ... | 1987 | 3656442 |
| transcription of the intergenic regions of the tubulin gene cluster of trypanosoma brucei: evidence for a polycistronic transcription unit in a eukaryote. | the tubulin genes of t. brucei are clustered in a tightly packed array of alternating alpha- and beta-genes. the steady state mrna contains one abundant mrna species each for alpha- and beta-tubulin, both carrying the identical 35 nt mini-exon sequence at their 5'-ends. we have used in vitro run-on transcription assays to investigate the mechanism of tubulin gene transcription in t. brucei. our results show that the regions between the individual tubulin genes are transcribed at the same rate as ... | 1987 | 3658696 |
| bovine trypanosomiasis in southern tanzania: parasitological and serological survey of prevalence. | in a survey for bovine trypanosomiasis blood smears from 1,617 cattle at 72 sites were examined. trypanosomes were found in 93 cattle, representing 16% of the cattle in herds in which trypanosomiasis was confirmed. of the positive cattle 56% had infections with t. congolense, 17% t. vivax and 2.2% t. brucei. five cattle had mixed infections and in 18 cattle the species was not identified. sera from 1,352 cattle were tested using microelisa. ten out of 16 sites, at which no trypanosomes were foun ... | 1987 | 3660451 |
| dihydrolipoamide dehydrogenase from trypanosoma brucei. characterization and cellular location. | dihydrolipoamide dehydrogenase has been discovered in the bloodstream form of the eukaryotic african parasite, trypanosoma brucei. the enzyme catalysed the stoichiometric oxidation of dihydrolipoamide by nad+ and exhibited a hyperbolic dependence of catalytic activity on the concentrations of both dihydrolipoamide and nad+. chemical modification with the tervalent arsenical reagent p-aminophenyldichloroarsine indicates the involvement in catalysis of a reversibly reducible disulphide bond. plasm ... | 1987 | 3663096 |
| inactivation of transcription by uv irradiation of t. brucei provides evidence for a multicistronic transcription unit including a vsg gene. | we have used inactivation of transcription by uv irradiation to map transcription units in trypanosomes. the relative inactivation rate of the transcription of mini-exon, 5s, and rrna genes was inversely proportional to the previously estimated lengths of these transcription units. the telomeric transcription unit containing the gene for variant-specific surface glycoprotein (vsg) 221 was inactivated as a single unit of 60 kb. this long transcription unit comprises at least one other protein-cod ... | 1987 | 3664637 |
| stable introduction of exogenous dna into trypanosoma brucei. | the lack of a homologous transformation system for trypanosomes is a serious handicap to the study of gene expression in these protozoans. attempts to develop such a system have been complicated by the lack of suitable homologous vectors and ignorance of the requirements for mrna synthesis which is discontinuous in trypanosomes. we have found that trypanosoma congolense, a close relative of t. brucei, contains exceptionally small chromosomes, which can be isolated whole and distinguished from th ... | 1987 | 3665883 |
| the investigation of trypanosoma brucei isolates obtained from glossina pallidipes in south nyanza, kenya. | during studies to determine the main trypanosoma brucei rhodesiense transmission sites in lambwe valley, western kenya, glossina pallidipes were collected from two areas in the valley and examined for trypanosome infection. t. brucei isolated from infected flies were tested for their response to the lethal effects of human blood (blood incubation infectivity test, biit) and also characterized using isoenzyme electrophoresis. six of the 26 t. brucei tested were biit positive, two of which had enz ... | 1987 | 3669129 |
| developmental regulation of a novel repetitive protein of trypanosoma brucei. | trypanosoma brucei undergoes many morphological and biochemical changes during transformation from the bloodstream trypomastigote to the insect procyclic trypomastigote form. we cloned and determined the complete nucleotide sequence of a developmentally regulated cdna. the corresponding mrna was abundant in in vitro-cultivated procyclics but absent in bloodstream forms. the trypanosome genome contains eight genes homologous to this cdna, arranged as four unlinked pairs of tandem repeats. the lon ... | 1987 | 3670296 |
| identification of two integral glycosomal membrane proteins in trypanosoma brucei. | glycosomal membranes of bloodstream form trypanosoma brucei were purified to apparent homogeneity by sodium carbonate treatment and found to contain two major integral membrane proteins of 26 kda (band 10) and 24 kda (band 11). the procyclic-form glycosomal membranes isolated by the same procedure also resulted in a homogeneous preparation, but each piece of membrane thus purified was associated with an electron-dense granule. procyclic membranes also contained primarily bands 10 and 11. these t ... | 1987 | 3670344 |
| use of species-specific dna probes for detection and identification of trypanosome infection in tsetse flies. | species- and subspecies-specific trypanosome dna hybridization probes have been employed in the detection and identification of trypanosome infections in glossina morsitans centralis. several ways of sample preparation including the use of tsetse organ suspensions, proboscides and dissected midguts, as well as tsetse abdominal content touch-blots were explored. the results of hybridization of radio-isotope-labelled species-specific dna probes to tsetse samples indicated that it was possible to d ... | 1987 | 3670893 |
| efflux of 3h-thymidine by erythrocytes from mice infected with trypanosoma brucei brucei. | erythrocytes from mice infected with trypanosoma brucei brucei showed a higher rate of efflux of labelled thymidine than did control erythrocytes from uninfected mice (0.56 +/- 0.10 and 0.38 +/- 0.06 mumole min-1 ml-1 packed cells respectively). efflux of the nucleoside from erythrocytes of normal and infected mice were inhibited to the same extent by a specific nucleoside transport inhibitor, nitrobenzylthioinosine. enumeration of nitrobenzylthioinosine binding sites on the erythrocytes showed ... | 1986 | 3675031 |
| trypanosoma brucei: polyamine oxidase mediated trypanolytic activity in the serum of naturally resistant cattle. | trypanosoma brucei brucei are lysed when incubated in vitro in a mixture of bovine serum and polyamine. normal bovine serum alone or polyamine alone does not show any trypanocidal activity. the bovine serum in the mixture can be replaced by purified polyamine oxidase, and addition of polyamine oxidase inhibitors blocks trypanolysis. using this in vitro lysis test, it is shown that west african cattle which are resistant naturally to trypanosomiasis have a higher trypanolytic activity in their se ... | 1987 | 3678446 |
| effect of tetracycline administration on the efficacy of diminazene aceturate therapy and prophylaxis in trypanosoma brucei infections of mice. | the simultaneous administration, to trypanosoma brucei infected mice, of rolitetracycline or oxytetracycline and diminazene aceturate appeared to have no effect on the initial trypanocidal action of the diminazene aceturate in that trypanosomes were cleared from the circulation. it also had no effect on the duration of the aparasitaemic period which follows diminazene aceturate treatment and the mice remained free of circulating trypanosomes for some time. however, if used prophylactically, rela ... | 1987 | 3685629 |
| trypanosoma b. brucei: a culture medium reverting a monomorphic to a pleomorphic strain. | a monomorphic strain of trypanosoma b. brucei cultured for 5 days at 37 degrees c in eagle's minimum essential medium (with or without feeder cells) supplemented with nu-serum became pleomorphic after inoculation into mice. dividing stumpy forms were still seen in blood after the third mouse passage. the strain remained monomorphic when cultured in the medium supplemented with foetal calf serum. this supports the hypothesis that some slender forms, under certain conditions, have the genetic capa ... | 1987 | 3686636 |
| development of trypanosoma brucei in suckling mouse brain following intracerebral injection. | intracerebral inoculation of trypanosoma b. brucei and t. b. rhodesiense into suckling mice produced infection of brain tissue which subsequently gave rise to an infection of the blood and other tissues, in which a normal histopathological picture was observed. treatment of other intracerebrally infected sucklings with 5 mg/kg diminazene aceturate (berenil) to clear the infection from the blood permitted a study of the course of the infection in the brain without interference from pathological p ... | 1987 | 3686641 |
| repression and reactivation of the variant surface glycoprotein gene in trypanosoma brucei. | rapid repression of variant surface glycoprotein (vsg) synthesis is an early event during the in vitro transformation of trypanosoma brucei from coated bloodstream forms to uncoated procyclic cells. repression occurs at the transcriptional level and is triggered by the combined action of two signals: a reduction in temperature from 37 to 27 degrees c and the addition of the citric acid cycle intermediates citrate and cis-aconitate. it is shown that synthesis of vsg mrna can be reactivated up to ... | 1987 | 3691806 |
| culture form and tsetse fly midgut form procyclic trypanosoma brucei express common proteins. | proteins expressed by culture form and tsetse fly midgut form procyclic trypanosomes were examined by polyacrylamide gel electrophoretic techniques. analysis of the proteins of the two forms of procyclic organisms was performed by comparison of autoradiographs of high resolution two-dimensional polyacrylamide gels prepared using [35s]methionine-labelled parasites. only eight spots were found to differ between autoradiographs of culture form and tsetse fly midgut form parasites. seven of these di ... | 1987 | 3696176 |
| controlled turnover and 3' trimming of the trans splicing precursor of trypanosoma brucei. | the maturation of mrnas in trypanosoma brucei involves a novel step, in which a short capped sequence is spliced in trans onto the 5' end of nascent mrnas from a 140-nucleotide precursor. this precursor is called the mini-exon-derived rna or medrna. we have used drugs and ultraviolet irradiation as inhibitors to probe the synthesis and processing of medrna in vivo. inhibition of rna synthesis by chloroquine shows that the half-life of medrna is about 4 minutes. despite this high turnover, only l ... | 1987 | 3697089 |
| trypanosoma brucei: release of variant surface glycoprotein during the parasite life cycle. | african trypanosome variant surface antigen, which was released from the trypanosoma brucei parasite at two stages in its life cycle, has been characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence of 4 m urea. variant surface antigen released as exoantigen into the bloodstream of infected rats resembled the soluble form of the surface antigen. variant surface antigen released from parasites undergoing transformation to the uncoated procyclic stage was detecte ... | 1986 | 3709754 |
| trypanosoma brucei brucei variant surface glycoprotein contains non-n-acetylated glucosamine. | the c-terminal amino acid of the variant surface glycoprotein of the parasitic protozoan trypanosoma brucei brucei is glycosylated and the oligosaccharide has been shown to contain glucosamine. by acid hydrolysis, hno2 deamination and 1h-n.m.r. studies we have demonstrated that the amino group of this glucosamine is not n-acetylated and is most probably unmodified. | 1986 | 3718481 |
| trypanosoma brucei and t. vivax: salicylhydroxamic acid and glycerol treatment of acute and chronically infected rats. | in rats infected with monomorphic trypanosoma brucei brucei, the efficacy of the therapy with salicylhydroxamic acid plus glycerol, i.e., combined therapy, decreased with increasing time after infection. it failed completely after the infection was made chronic by suboptimal treatment for 6 weeks. when this chronic infection had been established and "optimal" treatment was given, viable trypanosomes could still be detected 1 day later in brain and muscle but not in blood. in most organs, the con ... | 1986 | 3720904 |
| biochemical and immunological characterization of the variant surface coat glycoprotein shed by african trypanosomes. | as the variant surface coat glycoprotein (vsg) was shed from trypanosoma brucei rhodesiense into the blood of infected rats, it was biochemically characterized and compared with vsg that had been purified from trypanosomal homogenates. to determine if vsg was in association with lipid, membranes and lipoproteins in plasma of infected rats (irp), vsg isolated from plasma (pvsg), and vsg isolated from trypanosomal homogenates (hvsg) were all concentrated by ultracentrifugation and assayed for the ... | 1986 | 3721578 |
| posttranslational modification and intracellular transport of a trypanosome variant surface glycoprotein. | after synthesis on membrane-bound ribosomes, the variant surface glycoprotein (vsg) of trypanosoma brucei is modified by: (a) removal of an n-terminal signal sequence, (b) addition of n-linked oligosaccharides, and (c) replacement of a c-terminal hydrophobic peptide with a complex glycolipid that serves as a membrane anchor. based on pulse-chase experiments with the variant iltat-1.3, we now report the kinetics of three subsequent processing reactions. these are: (a) conversion of newly synthesi ... | 1986 | 3722267 |
| calcium ions initiate the selective depolymerization of the pellicular microtubules in bloodstream forms of trypanosoma brucei. | calcium ions (100 microm) were found to initiate the selective and complete depolymerization of the pellicular microtubules of trypanosoma brucei. the ca2+-dependent release of tubulin was found to occur without the detectable mediation of calmodulin. the released, depolymerized, pellicular tubulin from t. brucei cross-reacted with a monoclonal antibody raised against yeast tubulin. the pellicular tubulin was found to be composed of two alpha isotypes (apparently equal amounts) and one beta isot ... | 1986 | 3722278 |
| the comparative effects of cortisol and voltaren on anaemia and temperature changes in experimental trypanosoma brucei infection in rats. | three groups of rats were infected with trypanosoma brucei. two of the groups were treated with either asteroidal (cortisol) or a non-steroidal (voltaren) anti-inflammatory drug to compare the effects of the two drugs on the disease process. the anaemia was least severe in the cortisol treated group which suggests that its supportive use in the treatment of natural infections with the brucei subgroup of trypanosomes may be advantageous. | 1986 | 3722472 |
| parasitology. clandestine sex in trypanosomes. | | 1986 | 3724856 |
| hybrid formation between african trypanosomes during cyclical transmission. | trypanosomes of the species trypanosoma brucei reproduce primarily by binary fission, but the frequency of enzyme electrophoretic variants in natural populations of t. brucei has provided indirect evidence for the existence of a sexual cycle. these studies, coupled with studies of restriction fragment length polymorphisms of genes encoding glycolytic enzymes, have also provided evidence for t. brucei being diploid. here we report direct evidence of gene exchange between two different clones of t ... | 1986 | 3724860 |
| trypanosoma brucei rhodesiense: cell surface lectin-binding capacity. | | 1986 | 3727583 |
| extrachromosomal inheritance of susceptibility to trypanosome infection in tsetse flies. ii. susceptibility of selected lines of glossina morsitans morsitans to different stocks and species of trypanosome. | two lines of glossina m. morsitans, selected for susceptibility and refractoriness to infection with a single stock of trypanosoma congolense, have now been shown to be susceptible or refractory to different stocks of t. congolense and, also, to different stocks of t. b. brucei and t. b. gambiense. the mean midgut infection rates of the susceptible line obtained in different experiments with t. congolense, t. b. brucei and t. b. gambiense were, respectively, 66%, 56% and 55%; the corresponding m ... | 1986 | 3729601 |
| infectivity of trypanosoma rhodesiense cultivated at 28 degrees c with various tsetse fly tissues. | metacyclic trypanosomes developed in populations of procyclic forms of four stocks of trypanosoma brucei rhodesiense cultivated at 28 degrees c in a liquid medium containing explants of tsetse fly head-salivary glands, alimentary tract, abdominal body wall, or thoracic muscle. the cultures became infective for mice 7-16 days after they were prepared, and infective trypanosomes were present for prolonged periods. in the culture series of stock trum 545, infectivity persisted for 138 days when the ... | 1986 | 3735153 |
| tubulin mrnas of trypanosoma brucei. | the tubulin genes of trypanosoma brucei are located in a single, tightly packed cluster of ten tandemly arranged alternating alpha and beta-genes. no tubulin genes are detected outside the clustered array. therefore, the cluster can be assumed to be the locus of tubulin gene expression. single bands of alpha and beta-tubulin mrnas are observed in cultured procyclic as well as in bloodstream trypanosomes. both alpha and beta-tubulin mrnas have distinct 5' termini, which carry a 35-nucleotide mini ... | 1986 | 3735427 |
| inhibition of glyceraldehyde-3-phosphate dehydrogenase by pentalenolactone in trypanosoma brucei. | pentalenolactone (pl), an antibiotic produced by several strains of streptomycetes, is a specific irreversible inhibitor of glyceraldehyde-3-phosphate dehydrogenase (ec 1.2.1.12). the effect of this antibiotic was studied in trypanosoma brucei. in infected mice, due to the rapid metabolic inactivation of pl in vivo, trypanosomes were not affected by concentrations that were lethal to the host. bloodstream trypanosomes in vitro were killed by low concentrations of pl (1.5 microgram ml-1), suggest ... | 1986 | 3736593 |
| p-alkyloxybenzhydroxamic acids, effective inhibitors of the trypanosome glycerol-3-phosphate oxidase. | energy production in bloodstream forms of african trypanosomes of the genus trypanosoma involves two pathways unique to the parasite and which can be blocked by a combination of salicylhydroxamic acid (sham) and glycerol. although this leads to rapid parasite destruction both in vitro and in vivo, the toxicity of sham precludes practical use of sham/glycerol as a therapeutic regimen. based on our hypothesis that sham operates by interfering with ubiquinone, we attempted to develop this approach ... | 1986 | 3736594 |