| diagnosis of rhodesian sleeping sickness in the lambwe valley (1980-1984). | in primary rhodesian sleeping sickness patients, parasitological diagnosis was best performed by rodent inoculation of blood (98.5%+) followed by giemsa-stained thick blood smears (93.3%+). parasitological diagnosis in relapse patients was sometimes impossible and clinical diagnosis based on csf examination was necessary. early during a disease outbreak in 1980, 89% of the infections were detected by mobile field teams, but once established in the endemic area a stationary diagnostic facility de ... | 1989 | 2694986 |
| immunodiagnostic tests on cerebrospinal fluid in the diagnosis of meningoencephalitic trypanosoma brucei rhodesiense infection. | fourteen cerebrospinal fluid (csf) samples obtained from rhodesian sleeping sickness patients from the lambwe valley at relapse were positive for the presence of anti-trypanosomal antibody by both ifat and elisa. the mean optical density (o.d.) in the elisa test was 0.804 +/- 0.362 and ranged from 0.258 to 1.363. csf from five patients from the same area without evidence of meningoencephalitis were all negative by elisa (mean o.d. 0.023 +/- 0.016, range 0.011-0.051). control csf samples from u.k ... | 1989 | 2694987 |
| antigenic variation in relation to vaccines. | | 1989 | 2698082 |
| evaluation of enzyme immunoassays in the diagnosis of camel (camelus dromedarius) trypanosomiasis: a preliminary investigation. | three enzyme immunoassays were used for the serodiagnosis of trypanosoma evansi in camels in the sudan in order to evaluate their ability to discriminate between infected and non-infected animals. two assays were used for the detection of trypanosomal antibodies, one using specific anti-camel igg conjugate and another using a non-specific protein a conjugate. the third assay detected the presence of trypanosomal antigens using anti-t. evansi antibodies in a double antibody sandwich assay. inspec ... | 1989 | 2703023 |
| elevated phosphoglycerate kinase mrna but not protein in monomorphic trypanosoma brucei: implications for stage-regulation and post-transcriptional control. | phosphoglycerate kinase (pgk) is present in high levels in the glycosomes of bloodstream stage trypanosoma brucei, but is virtually absent in procyclic stage glycosomes. glycosomes isolated from slender and stumpy stage bloodforms show similar levels of pgk, although levels are slightly lower in stumpy forms. lower levels of glycosomal pgk transcripts are observed in stumpy form rna, paralleling the decrease in glycosomal pgk activity. monomorphic strains and pleiomorphic strains show similar gl ... | 1989 | 2704387 |
| trypanothione is the primary target for arsenical drugs against african trypanosomes. | the trypanosomatid metabolite n1,n8-bis-(glutathionyl)spermidine (trypanothione) has been demonstrated to form a stable adduct with the aromatic arsenical drug melarsen oxide [p-(4,6-diamino-s-triazinyl-2-yl)aminophenyl arsenoxide]. the stability constant of the melarsen-trypanothione adduct (mel t) has been determined to be 1.05 x 10(7) m-1. when bloodstream trypanosoma brucei are incubated with either melarsen oxide or the 2,3-dimercaptopropanol adduct of melarsen oxide (melarsoprol), mel t is ... | 1989 | 2704738 |
| interference in the establishment of tsetse-transmitted trypanosoma congolense, t. brucei or t. vivax superinfections in goats already infected with t. congolense or t. vivax. | an interference phenomenon that delays superinfection with a trypanosome species different from that used for the initial infection has been found to occur in goats. following tsetse transmission of trypanosoma brucei to goats already infected with t. congolense, there was a delay in chancre development, as well as in the appearance of t. brucei and anti-t. brucei antibodies in the blood when compared to previously uninfected goats. however, there was no delay in the establishment of a tsetse-tr ... | 1989 | 2705284 |
| synthesis of trypanosome hsp70 mrna is resistant to disruption of trans-splicing by heat shock. | synthesis of mrna in trypanosomes involves an apparent trans-splicing reaction whereby a common 39-nucleotide mini-exon sequence is joined to the protein-coding exon of a mrna precursor. we have previously shown (muhich, m. l., and boothroyd, j. c. (1988) mol. cell. biol. 8, 3837-3846) that the trans-splicing pathway of trypanosoma brucei is sensitive to disruption by severe heat shock. here we demonstrate that the synthesis of heat shock protein 70 (hsp 70) mrna in t. brucei is apparently resis ... | 1989 | 2708359 |
| identification of a developmentally regulated cysteine protease of trypanosoma brucei. | trypanosoma brucei undergoes dramatic metabolic changes during differentiation from the mammalian bloodstream form into the procyclic form of the insect midgut. because modulation of protein degradation is likely to be important during this process we studied t. brucei for life cycle mediated proteolysis. we detected an increase in the activity of a 28 kda protease as pleomorphic gutat 3.1 trypanosomes differentiate in the mammalian bloodstream from long slenders into short stumpies. short stump ... | 1989 | 2710163 |
| expression site associated genes of trypanosoma brucei rhodesiense. | upstream of at least some telomere-linked genes for the variant surface glycoproteins (vsgs) of african trypanosomes are expression site associated genes (esags) whose transcription is co-ordinated with the transcription of the adjacent vsg gene [cully et al. (1985) cell 42, 173-182]. the function of the corresponding esag proteins is not known. here we show the sequences of two members of the esag-i family that are upstream of the vsg genes expressed in metacyclic variant antigen types 4 and 7 ... | 1989 | 2710164 |
| phosphorylation of fructose bisphosphate aldolase in trypanosoma brucei. | methods were developed for in vivo labelling of trypanosome proteins with inorganic phosphate and the labelling of fructose bisphosphate aldolase and variant surface glycoprotein was investigated. it was found that the large pool size of phosphate in trypanosomes precludes detailed kinetic analyses. aldolase contains low levels of phosphoserine but the function of this phosphorylation has yet to be determined. | 1989 | 2710165 |
| colonies of procyclic trypanosoma brucei on semi-solid agarose plates. | | 1989 | 2710171 |
| efficacy of experimental trypanocidal compounds against a multiple drug-resistant trypanosoma brucei brucei stock in mice. | several experimental trypanocidal compounds, 6-amidino-2-(4-amidinophenyl)indole dilactate (dapi), dl-alpha-difluoromethylornithine (dfmo), 2-(dimethylamino)-4'-[(1-methyl-2-nitroimidazole-5-yl) methoxy] aceto-anilide (ro 15-0216), sinefungin, and triacetylbenzene-tris(guanylhydrazone)trimethanesulfonate hydrate (tbg-ms) were tested to evaluate their ability to cure mouse infections with a multiple drug-resistant trypanosoma brucei brucei stock (cp 547). this stock proved to be drug-resistant ag ... | 1989 | 2710771 |
| the role of succinate in the respiratory chain of trypanosoma brucei procyclic trypomastigotes. | trypanosoma brucei procyclic trypomastigotes were made permeable by using digitonin (0-70 micrograms/mg of protein). this procedure allowed exposure of coupled mitochondria to different substrates. only succinate and glycerol phosphate (but not nadh-dependent substrates) were capable of stimulating oxygen consumption. fluorescence studies on intact cells indicated that addition of succinate stimulates nad(p)h oxidation, contrary to what happens in mammalian mitochondria. addition of malonate, an ... | 1989 | 2719653 |
| the genes and transcripts of an antigen gene expression site from t. brucei. | the antat 1.3a antigen gene expression site of t. brucei was cloned from genomic libraries of the 200 kb expressor chromosome. in addition to the antigen gene, it contains seven putative coding regions (esags, for expression site-associated genes), as well as a rime retroposon. the polypeptide encoded by esag 4 shows homology to yeast adenylate cyclase, and possesses structural features of a transmembrane protein. the expression site is transcribed by a pol l-like polymerase in the parasite bloo ... | 1989 | 2720787 |
| evidence of myristylated disulfide-linked dimer of variant surface glycoprotein of trypanosoma brucei-brucei. | 1. variant surface glycoprotein (vsgs) of trypanosoma brucei-brucei may exist as a disulfide-linked dimer in both forms: myristylated (mfvsg) and non-myristylated (svsg), as judge by fluorography and immunoblotting of sds-page under non-reducing conditions. 2. the dimeric vsg form is labeled with [3h]-myristic acid in our incorporation conditions. 3. antat 1.1 trypanosomes preincubated with tunicamycin and incubated with [3h]-myristic acid synthesized a labeled molecule that has an apparent mole ... | 1989 | 2721157 |
| isolation and sequence of four small nuclear u rna genes of trypanosoma brucei subsp. brucei: identification of the u2, u4, and u6 rna analogs. | trypanosomes use trans splicing to place a common 39-nucleotide spliced-leader sequence on the 5' ends of all of their mrnas. to identify likely participants in this reaction, we used antiserum directed against the characteristic u rna 2,2,7-trimethylguanosine (tmg) cap to immunoprecipitate six candidate u rnas from total trypanosome rna. genomic southern analysis using oligonucleotide probes constructed from partial rna sequence indicated that the four largest rnas (a through d) are encoded by ... | 1989 | 2725495 |
| variation of tandem repeats in the developmentally regulated procyclic acidic repetitive proteins of trypanosoma brucei. | the procyclic acidic repetitive proteins (parps) of trypanosoma brucei are developmentally regulated surface proteins encoded by a family of polymorphic genes. we have determined the complete nucleotide sequence of a novel member of the parp gene family and investigated its expression. the amino acid sequence deduced from the parpa alpha gene showed a marked conservation of both the amino- and carboxy-terminal regions compared with other parps but revealed the substitution of a pentapeptide for ... | 1989 | 2725502 |
| improved separation of chromosome-sized dna from trypanosoma brucei, stock 427-60. | separation of chromosome-sized dna from the parasitic protozoan trypanosoma brucei had previously resulted in the fractionation of dna molecules that ranged in size from 50 kb up to roughly 1.5 mb. the number of larger chromosomes and their size, accounting for 80% of the dna of t. brucei remained unclear. we have now size separated these larger dna molecules by pulsed field gel electrophoresis (pfg) and resolve a total of 20 bands, accounting for roughly 120 chromosomes, ranging in size from 50 ... | 1989 | 2726456 |
| unusual c-terminal domain of the largest subunit of rna polymerase ii of crithidia fasciculata. | the c-terminal domain of the largest subunit of rna polymerase ii in higher eukaryotes is present in the protozoan parasite trypanosoma brucei in a strongly modified form. to determine whether this is a general feature of the kinetoplastida and to determine the role of this domain in rna polymerase ii transcription, we have analysed the c-terminal domain of the distantly related species crithidia fasciculata. no positional identity of amino acid residues between the c-termini of c. fasciculata a ... | 1989 | 2726483 |
| african trypanosomes: inheritance of factors involved in resistance. | the c3heb/fej mouse strain has a shorter survival time and is therefore more susceptible to a trypanosoma brucei rhodesiense infection than the b10.br/sgsnj strain. the work reported here demonstrated that survival time is inherited as a recessive trait, whereas the ability to produce antibody to the first variant antigen population is inherited as a dominant trait. it was therefore not possible to correlate survival time with the ability to produce antibody in the f-1 and f-2 offspring. both ch ... | 1989 | 2731583 |
| reversed phase hplc of different membrane-bound variant surface glycoprotein preparations from trypanosoma brucei brucei. | the chromatographic behaviour of the membrane-attached variant surface glycoprotein (mfvsg) of bloodstream forms of trypanosoma brucei brucei antat 1.1 a preparations were studied by reversed phase high performance liquid chromatography (rp-hplc). among the different preparation procedures used, only the trifluoroacetic acid extraction gave a mfvsg preparation which was eluted from the rp-hplc column. as well as for the soluble variant surface glycoprotein (svsg) it was found that different mfvs ... | 1989 | 2736318 |
| occurrence of human serum-resistant trypanosoma congolense in goats and sheep in nigeria. | an assessment of the role of dogs, goats and sheep as reservoir hosts of african trypanosomes infective for humans (sleeping sickness) was carried out in nigeria during a 2-year study period. twelve stocks of trypanosoma (trypanozoon) brucei, 10 stocks of trypanosoma congolense and 11 stocks of trypanosoma vivax were isolated from a total of 699 animals, comprising 286 sheep, 221 goats and 192 dogs. the potential infectivity of the isolates for man was tested in vitro using the blood incubation ... | 1989 | 2741299 |
| use of extracts of picralima nitida bark in the treatment of experimental trypanosomiasis: a preliminary study. | the effect of a boiling water extract of picralima nitida bark against trypanosomes (t. brucei) in rats was compared with that of diminazene aceturate at 8 mg/kg i.p. results showed that the extract had a definite trypanocidal effect which was statistically comparable to that of diminazene aceturate. further work is needed to identify the active pharmacological agent and to standardise the usage of the agent in practice. | 1989 | 2747261 |
| evidence for diploidy in metacyclic forms of african trypanosomes. | the dna contents of bloodstream form trypanosomes (life cycle stages circulating in the blood of the vertebrate host) of four african trypanosoma species and of metacyclic forms (the life cycle stage that is injected into the vertebrate by the tsetse fly during its bite) of the same four species were measured by cytofluorometry of individual cells or nuclei. the results showed unambiguously that the metacyclic forms cannot be considered to be products of meiosis containing only half of the dna o ... | 1989 | 2748597 |
| a novel telomeric gene conversion in trypanosoma brucei. | gene conversion is one mechanism of antigenic variation in trypanosoma brucei. variant surface glycoprotein (vsg) genes are duplicated by this process to telomeric locations from which they may be expressed. we examined four independent antigenic switches in which the istar 1.1 minichromosomal vsg gene is duplicated to a large chromosome where it is expressed. an unusual feature of three of these telomeric gene conversions is that the distance between the vsg gene and the end of the chromosome i ... | 1989 | 2761571 |
| trypanosomiasis in a rural hospital in tanzania. a retrospective study of its management and the results of treatment. | a retrospective analysis was done of the management and the results of treatment in 158 trypanosomiasis patients seen in a rural hospital in tanzania during 1985. the distribution of cases in the population and during the year reflected an endemic situation. 109 patients (68.9%) were in the meningoencephalitic (me) stage and 49 (31.1%) in the hematolymphatic (hl) stage of the disease. in total 19 patients (12.0%) died, 17 with me and 2 with hl trypanosomiasis. encephalopathy was seen in 19 (17.9 ... | 1989 | 2763355 |
| feeder layer-free in vitro assay for screening antitrypanosomal compounds against trypanosoma brucei brucei and t. b. evansi. | a drug-susceptible trypanosoma brucei brucei stock, a multidrug-resistant t. b. brucei stock, and a t. b. evansi stock resistant to two commercial trypanocides were adapted to a feeder layer-free culture system. bloodstream forms were grown continuously in a liquid medium at 37 degrees c in 4% co2 in air. samples of trypanosome populations in the logarithmic growth phase were incubated with various concentrations of commercial and experimental compounds. growth inhibition was monitored after a 2 ... | 1989 | 2764539 |
| in vitro differentiation between trypanosoma brucei brucei and t.b. evansi. | transformation experiments of bloodstream form trypanosomes into procyclics are described to differentiate the pleomorphic trypanosoma brucei brucei and the monomorphic t.b. evansi. stocks previously identified as t.b. brucei transformed into procyclics in vitro, whereas t.b. evansi did not. | 1989 | 2772515 |
| endocytosis by african trypanosomes. i. three-dimensional structure of the endocytic organelles in trypanosoma brucei and t. congolense. | african trypanosomes multiply rapidly during the course of infection obtaining nutrients from the host blood and other body fluids. the organelles involved in endocytosis were revealed ultrastructurally using horseradish peroxidase (hrp) and colloidal gold coupled to bovine transferrin (au-tf) or bovine serum albumin (au-bsa). at 0 degree c the markers bound to the cell surface and neither entered the flagellar pocket nor were internalized. upon warming to 37 degrees c, the markers were found in ... | 1989 | 2776775 |
| endocytosis by african trypanosomes. ii. occurrence in different life-cycle stages and intracellular sorting. | horseradish peroxidase (hrp) and colloidal gold-labeled proteins enter many of the endocytic organelles of bloodstream forms of trypanosoma brucei and t. congolense. however, the colloidal gold markers were excluded from substantial parts of the pathway that contained hrp. morphometric studies revealed that hrp entered organelles that accounted for approximately 5% of the total cell volume while transferrin-gold entered organelles that comprised approximately 2% of the total cell volume. in addi ... | 1989 | 2776776 |
| trypanosoma brucei: posttranscriptional control of the variable surface glycoprotein gene expression site. | the arrest of variable surface glycoprotein (vsg) synthesis is one of the first events accompanying the differentiation of trypanosoma brucei bloodstream forms into procyclic forms, which are characteristic of the insect vector. this is because of a very fast inhibition of vsg gene transcription which occurs as soon as the temperature is lowered. we report that this effect is probably not controlled at the level of transcription initiation, since the beginning of the vsg gene expression site, ab ... | 1989 | 2779574 |
| trypanosoma brucei: enrichment by uv of intergenic transcripts from the variable surface glycoprotein gene expression site. | the expression site for the variable surface glycoprotein (vsg) gene antat 1.3a of trypanosoma brucei is 45 kilobases long and encompasses seven expression site-associated genes (esags) (e. pays, p. tebabi, a. pays, h. coquelet, p. revelard, d. salmon, and m. steinert, cell 57:835-845, 1989). after uv irradiation, several large transcripts from the putative promoter region were strongly enriched. we report that one such major transcript starts near the poly(a) addition site of the first gene (es ... | 1989 | 2779575 |
| camel trypanosomiasis and its vectors in somalia. | blood samples from 3000 somali camels (camelus dromedarius) were examined for trypanosome infection. of these, 160 (5.33%) were infected with trypanosoma evansi, one (0.03%) with t. congolense and one (0.03%) with t. brucei. camel trypanosomiasis occurred in most areas of tabanid infestation throughout the country. the tabanids philoliche zonata and p. magretti are incriminated as the major vectors of the disease. | 1989 | 2781715 |
| specificity and kinetics of hexose transport in trypanosoma brucei. | transport of 6-deoxy-d-glucose was studied in trypanosoma brucei in order to characterise the kinetics of hexose transport in this organism using a nonphosphorylated sugar. kinetic parameters for efflux and entry, measured using zero-trans and equilibrium exchange protocols, indicate that the transporter is probably kinetically symmetrical. comparison of the kinetic constants of d-glucose metabolism with those for 6-deoxy-d-glucose transport shows that transport across the plasma membrane is lik ... | 1989 | 2790048 |
| glucosephosphate isomerase from trypanosoma brucei. cloning and characterization of the gene and analysis of the enzyme. | in trypanosoma brucei the enzyme glucose-6-phosphate isomerase, like most other enzymes of the glycolytic pathway, resides in a microbody-like organelle, the glycosome. here we report a detailed study of this enzyme, involving a determination of its kinetic properties and the cloning and sequence analysis of its gene. the gene codes for a polypeptide of 606 amino acids, with a calculated mr of 67280. the protein predicted from the gene sequence has 54-58% positional identity with its yeast and m ... | 1989 | 2792108 |
| trypanosoma brucei brucei: expression of drug resistance in vitro. | the susceptibility of five trypanosoma brucei brucei stocks to diminazene aceturate (berenil) and isometamidium chloride (samorin) was determined in vivo and in vitro. two stocks were resistant in mice to both drugs. differences in drug-induced growth inhibition occurred between drug-resistant and drug-sensitive stocks when trypanosome bloodstream forms were incubated for 24 hr at 37 degrees c in 4% co2 in air in a feeder layer-free culture system. diminazene concentrations which inhibited growt ... | 1989 | 2792303 |
| the major component of the paraflagellar rod of trypanosoma brucei is a helical protein that is encoded by two identical, tandemly linked genes. | the flagellum of the parasitic hemoflagellate trypanosoma brucei contains two major structures: (a) the microtubule axoneme, and (b) a highly ordered, filamentous array, the paraflagellar rod (pfr). this is a complex, three-dimensional structure, of yet unknown function, that extends along most of the axoneme and is closely linked to it. its major structural component is a single protein of 600 amino acids. this pfr protein can assume two different conformations, resulting in two distinct bands ... | 1989 | 2793936 |
| a glycolipid from trypanosoma brucei related to the variant surface glycoprotein membrane anchor. | the variant surface glycoprotein (vsg) of trypanosoma brucei is covalently linked to a phosphatidylinositol-containing glycolipid which serves as a membrane anchor. we previously identified a molecule, glycolipid a, which appears to be a biosynthetic precursor to the anchor [9]. in this paper we describe a related molecule, glycolipid c, which is similar to glycolipid a but which is more hydrophobic. chromatographic analyses indicate that the polar head groups in glycolipids a and c are similar ... | 1989 | 2797062 |
| detection of trypanosoma congolense and trypanosoma brucei subspecies by dna amplification using the polymerase chain reaction. | the nuclear dna of trypanosoma congolense contains a family of highly conserved 369 base pair (bp) repeats. the sequences of three cloned copies of these repeats were determined. an unrelated family of 177 bp repeats has previously been shown to occur in the nuclear dna of trypanosoma brucei brucei (sloof et al. 1983a). oligonucleotides were synthesized which prime the specific amplification of each of these repetitive dnas by the polymerase chain reaction (pcr). amplification of 10% of the dna ... | 1989 | 2797872 |
| high frequency of antigenic variation in trypanosoma brucei rhodesiense infections. | rates at which trypanosoma brucei rhodesiense trypanosomes switch from expression of one variable antigen type (vat) to that of another have been determined in cloned populations that have been recently tsetse-fly transmitted. switching rates have been determined between several, specific pairs of vats in each population. high rates of switching were observed in 2 cloned trypanosome lines, each derived from a separate cyclical transmission of the same parental stock and each expressing a differe ... | 1989 | 2797873 |
| vector susceptibility to african trypanosomes. | susceptibility of tsetse fly to trypanosome depends on two distinct barriers controlling respectively colonization of midgut and, migration to salivary glands. those barriers are modulated by barely known factors, pertaining to the physiological status of the fly as well as to cytoplasmic and nuclear inheritance. quantification of colonization (p) and migration (m) rates provides a way to calculate intrinsic vectorial capacity (ivc) as a product ivc = p x m, and to undergo comparative analysis o ... | 1989 | 2802818 |
| possible causes leading to an epidemic outbreak of sleeping sickness: facts and hypotheses. | sleeping sickness epidemics have been noted to occur with some degree of periodicity and the question as to why this is so has been asked for quite a long time. these epidemics have been partially controlled in the past using the conventional methods of bush clearing, mass diagnostic surveys and treatment. political, social and economic upheavals have been found to be very important factors in the recurrence of these epidemics. in addition, a number of facts and hypotheses have been advanced as ... | 1989 | 2802819 |
| the epidemiological relevance of trypanosome strain variation. | the study of strain variation in t.b. rhodesiense has yielded a lot of information which suggests that these trypanosomes are a sub-set of the stocks circulating in tsetse and non human hosts and that each focus constitutes a separate set of human infective stocks. these conclusions remain to be fully established by extensive studies in specific foci. whether the maintenance of these foci or the expansion of them into epidemics is dependent on variation in the trypanosoma stocks generated by mut ... | 1989 | 2802821 |
| current knowledge on epidemiology and control of sleeping sickness. | african trypanosomiasis (sleeping sickness) occurs in some 200 known foci within tsetse inhabited areas in sub-saharan africa, where an estimated 50 million people are at risk of acquiring infection. only 25,000 new patients are reported each year but this is an underestimate. where medical surveillance was inadequate or lacking, serious epidemics could occur and this potential risk makes the disease one of the serious health problems in sub-saharan africa. the chronic gambiense form of sleeping ... | 1989 | 2802823 |
| calculating the basic reproductive rate ro when there are 2 or more pathogens. | some reasons why observed prevalences of the 3 major trypanosomes in cattle and livestock animals might not be independent are discussed. apart from genuine interactions between the infections, averaging over heterogeneous populations produces an apparent correlation between pathogens. more subtly, chemotherapy and mortality both induce a positive correlation between pathogens. the calculation of the basic reproductive rate ro for one pathogen in the endemic presence of another is explained, and ... | 1989 | 2802830 |
| modulation of il-1 production and il-1 release during experimental trypanosome infections. | macrophage populations derived from trypanosoma brucei-infected mice suppress both interleukin-2 (il-2) production and il-2 receptor expression. to try to identify the regulatory level by which the t-cell activation is switched off, we have analysed the potential of the suppressive macrophage-like cells to block the secretion of the accessory cell-derived t cell co-stimulator interleukin-1 (il-1). the il-1 secretion, however, was found to be greatly increased rather than decreased. the increased ... | 1989 | 2807368 |
| respiration of bloodstream forms of the parasite trypanosoma brucei brucei is dependent on a plant-like alternative oxidase. | coq links the sn-glycerol-3-phosphate dehydrogenase and oxidase components of the cyanide-insensitive, non-cytochrome-mediated respiratory system of bloodstream african trypanosomes. in this and other characteristics, their respiratory system is similar to the alternative oxidase of plants. the parasites contain 206 ng of coq9 mg protein-1 which co-sediments with respiratory activity. the redox state of this coq responds in a manner consistent with respiratory function: 60% being in the reduced ... | 1989 | 2808350 |
| molecular characterization of the trypanosoma brucei rna polymerase i and iii largest subunit genes. | we have sequenced a 7.1-kilobase fragment of the trypanosoma brucei rna polymerase (pol) i largest subunit gene. the 6.9-kilobase transcript from this gene is of roughly equal abundance in bloodstream- and procyclic-form trypanosomes and has a 39-nucleotide trans-spliced leader 290 nucleotides upsteam of the putative initiation codon. the 1781-amino acid trypanosome pol i polypeptide is considerably less similar to its yeast homolog than the trypanosome pol ii and pol iii polypeptides are to the ... | 1989 | 2808366 |
| ornithine decarboxylase and trypanothione reductase genes in leishmania braziliensis guyanensis. | ornithine decarboxylase and trypanothione reductase are the key enzymes in polyamine and trypanothione metabolism in kinetoplastids. using a heterologous trypanosoma brucei brucei probe for ornithine decarboxylase and a mixed synthetic probe of 29 oligonucleotides for trypanothione reductase, we have detected the putative genes for these enzymes by southern blot hybridization using genomic dna of leishmania braziliensis guyanensis mhom/sr/80/cumc 1. the trypanothione reductase probe was construc ... | 1989 | 2810144 |
| possible role of the nadh-fumarate reductase in superoxide anion and hydrogen peroxide production in trypanosoma brucei. | mitochondrial membranes from trypanosoma brucei procyclic trypomastigotes generated superoxide anion and hydrogen peroxide in a 2:1 ratio when supplemented with nadh. fumarate inhibited hydrogen peroxide formation (ki = 16 microm) with the same affinity as it stimulated nadh-fumarate reductase activity. superoxide anion production was also 65% inhibited by fumarate (ki = 20 microm). the km for nadh of the nadh-fumarate reductase (60 microm) was also similar to that for hydrogen peroxide generati ... | 1987 | 2823135 |
| the structure and transcription of an element interspersed between tandem arrays of mini-exon donor rna genes in trypanosoma brucei. | messenger rnas in trypanosoma brucei brucei have the same 35 bases at the 5' end. these 35 bases are not encoded contiguously in the genome, but are donated from a 140 base rna (the mini-exon donor rna). the mini-exon donor rna (medrna) is encoded by 1.35 kbp genes that occur in tandem repeats. a dna element that is associated with mini-exon donor rna medrna genes has been identified and characterised by restriction enzyme mapping and partial sequencing. this element (the medrna gene associated ... | 1987 | 2827116 |
| receptor-mediated endocytosis in the bloodstream form of trypanosoma brucei. | the uptake of various host plasma proteins by the bloodstream form of trypanosoma brucei was studied both biochemically, using radiolabeled proteins, and with the electron microscope, using colloidal gold particles as molecular tracers onto which plasma proteins had been adsorbed. total plasma proteins and serum albumin were taken up by a mechanism of fluid endocytosis with low clearance (0.1 microliter [mg cell protein]-1 h-1), while low-density lipoprotein (ldl) and transferrin were taken up b ... | 1987 | 2828605 |
| the variable region of the trypanosoma brucei kinetoplast maxicircle: sequence and transcript analysis of a repetitive and a non-repetitive fragment. | the sequence of two fragments derived from the variable region of the kinetoplast maxicircle of trypanosoma brucei has been determined. one fragment (1334 nucleotides, situated immediately upstream of the 12s and 9s ribosomal rna genes) consists of non-repetitious dna, which does not hybridize to other maxicircle regions. the other (844 nt, located between 1.7 and 2.55 kb downstream of the nadh-dehydrogenase subunit 5 gene) contains arrays of repetitive sequences which are also found outside thi ... | 1988 | 2830510 |
| acetylcholinesterases from musca domestica and drosophila melanogaster brain are linked to membranes by a glycophospholipid anchor sensitive to an endogenous phospholipase. | the sensitivity of acetylcholinesterases (aches) from musca domestica and from drosophila melanogaster to the phosphatidylinositol-specific phospholipase c from bacillus cereus and to the glycosylphosphatidylinositol-specific phospholipase c from trypanosoma brucei was investigated. b. cereus phospholipase c solubilizes membrane-bound ache, and both phospholipases convert amphiphilic aches into hydrophilic forms of the enzyme. the lipases uncover an immunological determinant that is found on oth ... | 1988 | 2831298 |
| trypanosoma brucei variant-specific glycoprotein gene chromatin is sensitive to single-strand-specific endonuclease digestion. | active variant surface glycoprotein (vsg) gene chromatin is preferentially digested by the restriction enzyme hinfi in nuclei of bloodstream variants of trypanosoma brucei. hinfi sensitivity of vsg gene chromatin is not observed in nuclei of relapse variants in which the vsg gene has been inactivated in situ. active vsg gene chromatin is preferentially degraded by the single-strand-specific endonucleases s1 and bal31. this sensitivity is not the result of pre-existing single-strand breaks or a d ... | 1987 | 2831370 |
| a head-to-tail tandem organization of hsp70 genes in trypanosoma cruzi. | we describe the isolation and characterization of the t. cruzi hsp 70 dna coding region which was found to be formed by multigene copies organized in a tandem array in a head-to-tail manner. the restriction pattern of one of the repetition units within the largest clone obtained from the genomic library, clone tc70.6, shows that the hsp70 coding region should be formed by at least seven identical copies of 2.5 kb. we have found, however, the presence of restriction polymorphisms (pvu ii) within ... | 1988 | 2831499 |
| multiple events associated with antigenic switching in trypanosoma brucei. | the genomic environments of six unrelated variant surface glycoprotein (vsg) gene families in the istar 1 serodeme of trypanosoma brucei were examined by southern blot analysis of dna resolved by conventional and pulse field gradient electrophoresis. the genomic locations of these gene family members were characterized in variants arising from 19 independent antigenic switches of which 13 represent single relapses. we have identified 9 distinct telomeric sites containing vsg genes on 7 different ... | 1988 | 2842674 |
| changes in telomere length associated with antigenic variation in trypanosoma brucei. | in the istar 1 serodeme, we have identified variant surface glycoprotein (vsg) genes in nine different telomeric sites. we have measured the distance from the 3' end of these vsg genes to the end of the chromosome (the 'telomere length') in 20 variant antigen types (vats) of the serodeme. analyses of the changes in telomere length during 19 antigenic switches involving eight telomeric sites indicate a median increase in telomere length of 0.6 kilobase pairs during each switch. this may be accoun ... | 1988 | 2842675 |
| characterization of cytochrome c oxidase iii transcripts that are edited only in the 3' region. | the cytochrome c oxidase subunit iii (coiii) transcript of t. brucei is extensively edited by the addition and deletion of uridines. we have identified partially edited coiii rnas; they have unedited 5' and edited 3' regions. transcripts with edited 5' but unedited 3' regions were not detected. the partially edited rnas may be editing intermediates. the junctions of unedited and edited sequences in cdnas differ from both the dna and fully edited mrna sequences over a multinucleotide region. the ... | 1988 | 2844415 |
| discontinuously synthesized mrna from trypanosoma brucei contains the highly methylated 5' cap structure, m7gpppa*a*c(2'-o)mu*a. | trypanosoma brucei mrna is discontinuously synthesized via the 5' addition of a "mini-exon" sequence. the mini-exon-specific cap structure was purified from a complete rnase t2 and phosphatase digest of in vivo 32p-labeled poly(a)+rna. the purified cap structure was sequenced by a series of partial and complete enzymatic digests by nuclease p1 and venom phosphodiesterase. this approach demonstrated that the t. brucei mini-exon cap structure consists of n7-methylguanosine linked in a conventional ... | 1988 | 2844798 |
| the potentiation of arsenicals with difluoromethylornithine (dfmo): experimental studies in murine trypanosomiasis. | the efficacy of melarsoprol in the treatment of chronic t. b. brucei infections in mice can be increased approximately 5 times if dl-a-difluoromethylornithine (dfmo) is given in the drinking water at the same time. a more detailed study substantiated the concept that a reduction in both the size and the rate of replacement of the trypanothione pool are the key factors in the efficiency of melarsoprol chemotherapy. it was therefore best to give the melarsoprol towards the end of the dfmo regimen, ... | 1988 | 2848638 |
| posttranscriptional regulation of cytochrome c expression during the developmental cycle of trypanosoma brucei. | we examined the expression of a nucleus-encoded mitochondrial protein, cytochrome c, during the life cycle of trypanosoma brucei. the bloodstream forms of t. brucei, the long slender and short stumpy trypanosomes, have inactive mitochondria with no detectable cytochrome-mediated respiration. the insect form of t. brucei, the procyclic trypanosomes, has fully functional mitochondria. cytochrome c is spectrally undetectable in the bloodstream forms of trypanosomes, but during differentiation to th ... | 1988 | 2850466 |
| coordinate transcription of variant surface glycoprotein genes and an expression site associated gene family in trypanosoma brucei. | trypanosoma brucei variant surface glycoprotein (vsg) genes are activated either by duplicative (da) transposition of the gene to a pre-activated expression site or by nonduplicative (nda) activation of a previously silent telomeric gene. we have obtained a recombinant clone spanning the 5' barren region of the expression linked copy of the duplicated vsg gene 117a. by dna sequence and hybridization analyses we have identified a pleomorphic family of 14-25 non-vsg genes that lie upstream of both ... | 1985 | 2861910 |
| specific immunity in rats inoculated with trypanosoma brucei brucei derived from tsetse salivary glands and cultured in vitro. | twenty rats were each immunized intraperitoneally with 1.25 x 10(7) formalin-fixed trypanosoma brucei brucei (stock eatro 1969) derived from tsetse salivary glands and propagated in culture at 29 degrees c in their infective form for more than 1000 days. another group, consisting of 10 rats, was similarly immunized with parasites of stock eatro 999 derived from salivary glands of a tsetse fly and propagated in culture for more than 360 days. immunized animals were resistant to homologous challen ... | 1985 | 2862773 |
| two simple media for biochemical experimentation with cultured procyclic trypanosoma brucei. | two simple media are presented which are particularly well suited for biochemical experimentation with procyclic culture forms of trypanosoma brucei. me-83 is a simple semi-defined medium which supports active cell growth, and from which individual components can conveniently be deleted or replaced. hhp-84 is a fully defined minimal medium, which allows vigorous cell motility over extended times, but in which cell proliferation is not occurring. | 1985 | 2862774 |
| [experimental nagana infections in camels (camelus dromedarius)]. | | 1985 | 2866763 |
| in vitro activity of the trypanocidal diamidine dapi on animal-infective trypanosoma brucei brucei. | a mammalian feeder layer system for the continuous cultivation of infective bloodstream forms of trypanosoma brucei brucei has been used for investigating the antitrypanosomal activity of the aromatic diamidine dapi. the drug was active at concentrations which can be reached under physiological conditions. the minimum effective concentration was 0.05 micrograms/ml. minimum exposure times required for antitrypanosomal activity were dependent on the drug concentrations. furthermore, dapi was found ... | 1985 | 2868631 |
| characterization of cyclically transmitted trypanosoma (t.) brucei isolates from man. | four different trypanosome isolates from human patients isolated in 1979 during the epidemic of sleeping sickness in busoga, south-east uganda, were characterized by the following methods: isoenzyme analyses of bloodstream forms by isoelectric focusing; in vitro tests of human serum resistance of bloodstream as well as metacyclic forms; tsetse fly transmission through glossina morsitans centralis and glossina morsitans morsitans to compare the above characteristics of parasite populations before ... | 1986 | 2872784 |
| defence reactions of glossina morsitans morsitans against different species of bacteria and trypanosoma brucei brucei. | tsetse flies, glossina morsitans morsitans, fed on rats infected with trypanosoma brucei brucei showed wide fluctuations in total and differential haemocyte counts. similar fluctuations occurred in controls fed on non-infected rats and also between the two groups without showing any difference which could be attributed to the infection. trypanosome infection of the tsetse haemocoel occurred in 16.25% of the flies, starting from the second day after feeding on the infected rats, but salivary glan ... | 1986 | 2872785 |
| developmental regulation of trypanosome mitochondrial gene expression. | mitochondrial respiratory activities in the protozoan parasite trypanosoma brucei are developmentally regulated. the trypanosomes in the mammalian bloodstream derive atp entirely from glycolysis. the trypanosomes found in the midgut of the insect vector or in culture at 26 degrees c have fully functional mitochondria with cytochrome-mediated respiration. in this paper, we show that the steady state levels of the 9 s and 12 s mitochondrial ribosomal rnas (rrnas) are 30-fold lower in an early deve ... | 1987 | 2879836 |
| active suppression of interleukin 2 secretion in mice infected with trypanosoma brucei antat 1.1.e. | impairment of t cell proliferation in mice infected with the pleomorphic trypanosoma brucei antat 1.1 e clone was found not to be related to a depletion of t cells or to an absence of functional accessory cells, but rather to an active suppression of interleukin 2 (il-2) production. lymph node cells derived from infected mice failed to produce il-2 following con a stimulation, whereas an exogenous supply of recombinant il-2 could restore the impairment of the mitogen (con a)-induced proliferativ ... | 1986 | 2880330 |
| localization of 3'-nucleotidase and calcium-dependent endoribonuclease in the plasma-membrane of trypanosoma brucei. | we have characterized a 3'-nucleotidase activity of t. brucei. the enzyme has a ph optimum of 8.7, is inactivated by chelating agents and stimulated by divalent cations. it is inhibited by zn2+, mn2+, pyrophosphate and the trypanocidal drug suramin for which it has a ki of 3 microm. from cell fractionation experiments it is concluded that the enzyme is located in the plasma membrane. alkaline 3'-endoribonuclease is also located in the plasma membrane of t. brucei and this activity shares a great ... | 1986 | 2882657 |
| freeze-fracture studies on the surface membranes of pleomorphic bloodstream and in vitro transformed procyclic trypanosoma brucei. | the surface membranes of bloodstream long slender, short stumpy and culture procyclic stages of trypanosoma brucei brucei were compared with respect to freeze-fracture electron microscopy, intramembrane particle (imp) distribution and beta-hydroxysterol content as shown by the characteristic intramembrane lesions induced by the polyene antibiotic, filipin. little difference was observed between imp density of long slender and short stumpy form body membranes: imp's were more abundant on the prot ... | 1986 | 2882658 |
| use of procyclic trypanosomes for detection of antibodies in sera from vervet monkeys infected with trypanosoma rhodesiense: an immunodiagnostic test for african sleeping sickness. | uncoated procyclic culture forms of african trypanosomes were used in immunofluorescence and simple agglutination assays to detect antibodies in the sera of vervet monkeys infected with t. b. rhodesiense. antibodies to procyclic surface antigens were found in sera from animals with active, untreated infections or sera taken soon after treatment with trypanocidal drugs. the antibodies were detectable within 7 days of infection. no specific antibodies were detected in sera prior to infection or lo ... | 1986 | 2882666 |
| pathogenicity of crithidia fasciculata in the haemocoele of glossina. | the mosquito flagellate crithidia fasciculata produces intense haemocoelic infections following intrahaemocoelic inoculation into 5 species of glossina--g. austeni, g. fuscipes fuscipes, g. morsitans morsitans, g. palpalis gambiensis and g. tachinoides. all glossina inoculated with c. fasciculata died between days 4 and 9. neither trypanosoma brucei procyclics nor leishmania hertigi promastigotes similarly inoculated into glossina species, at the same dose, multiplied within the haemocoele and n ... | 1987 | 2884835 |
| the effect of trypanocidal drugs on the transmission of trypanosoma brucei brucei by glossina morsitans centralis. | the effects of trypanocidal drugs on trypanosoma b. brucei infections in glossina m. centralis have been investigated. pentamidine and suramin exhibited no significant effects but both berenil and samorin reduced the number of salivary gland infections in comparison with controls. berenil at concentrations of 10, 1.0 and 0.1 microgram/ml significantly reduced the number of mature infections when fed to flies throughout the whole period of trypanosome development. a similar result was obtained wi ... | 1987 | 2884836 |
| epidemiology of animal trypanosomiasis on a cattle ranch in kilifi, kenya. | a study of the epidemiology of animal trypanosomiasis was carried out on a 2500 ha cattle ranch, with a history of trypanosomiasis, in the coast province of kenya in 1982. the tsetse survey on the ranch revealed one breeding focus of glossina austeni in a thicket of approximately 50 ha. trypanosomes were detected in 20% of the 46 dissected tsetse. during the study period of 9 months, 0.8% of the 3315 samples collected from 2300 ayrshire x sahiwal crossbred cattle were found infected with trypano ... | 1987 | 2884841 |
| dna contents and molecular karyotypes of hybrid trypanosoma brucei. | we have used restriction fragment length polymorphism markers to characterise parental and hybrid trypanosome stocks. unexpected differences in the intensities of southern hybridisation banding patterns led us to suspect that the hybrid organisms contained more dna than the parental stocks. this has been confirmed using flow cytofluorimetry (fcf). hybrids contained significantly more dna than the parents, both as procyclic organisms (1.5 fold) and as bloodstream forms (1.5-1.6 fold). the dna con ... | 1987 | 2886912 |
| unloaded polyisobutylcyanoacrylate nanoparticles: efficiency against bloodstream trypanosomes. | the potential use of polyisobutylcyanoacrylate nanoparticles in antiparasitic chemotherapy is described. the nanoparticles on their own proved to have trypanocidal activity against trypanosoma brucei brucei in-vitro but not against trichomonas vaginalis or entamoeba histolytica. the trypanocidal activity was partly confirmed in-vivo with t. brucei-infected mice. | 1987 | 2888859 |
| the effect of trypanosoma brucei infection of the localization of salivary gland cholinesterase in glossina morsitans morsitans. | when salivary glands of the tsetse fly, glossina morsitans morsitans, are stained for cholinesterase (che) activity, a net-like pattern of reaction product is observed surrounding each epithelial cell of the gland's secretory region. glands infected with trypanosoma brucei brucei show a progressive reduction in this che activity as the parasites develop. when the infection is mature, che is rarely detected in the epithelial layer but appears in the lumen of gland. the luminal che responds to sub ... | 1987 | 2892368 |
| studies on experimental infection of pigs with trypanosoma brucei. | | 1987 | 2892375 |
| gene exchange in african trypanosomes: characterisation of a new hybrid genotype. | we describe the isolation of a hybrid trypanosoma brucei clone following the mixed cyclical transmission of two parental clones through tsetse flies. the characterisation of this clone reveals some new facets of the process of genetic exchange in t. brucei. the inheritance of four isoenzyme loci and restriction fragment polymorphisms at two loci was interpretable in 'mendelian' genetic terms, involving meiosis either before or after the genetic exchange event. however, at a further two isoenzyme ... | 1988 | 2893975 |
| competent metabolic utilization of hydrogen peroxide by trypanosomes. | | 1987 | 2894136 |
| cultivation of the life cycle stages of trypanosoma brucei sspp. | a culture system was devised for the production of the various stages in the developmental cycle of trypanosoma brucei brucei and t. b. rhodesiense. the bloodstream forms were grown at 37 degrees c on a feeder layer of fibroblasts from embryos of microtus montanus or cd-1 mice in hepes-buffered minimum essential medium with earle's salts, supplemented with 15% heat-inactivated rabbit serum. when they were transferred to hepes-buffered cunningham's medium and incubated at 27 degrees c, they trans ... | 1988 | 2896444 |
| the relapse of trypanosoma brucei brucei infections after chemotherapy in rabbits. | infections of t. brucei in the rabbit were found to relapse after chemotherapy. the results indicated that 25 mg/kg diminazene aceturate given 3 days after infection resulted in a complete cure but if given 7 days after infection relapses frequently occurred. however, treatment was apparently successful if delayed until 14 or 21 days. six of the rabbits originally treated with diminazene aceturate on day 7 were treated with suramin 21 days later; in 3 rabbits the infections relapsed. in all rabb ... | 1988 | 2896445 |
| metabolism of phospholipids and lysophospholipids by trypanosoma brucei. | african trypanosomes (trypanosoma brucei brucei) rapidly metabolize exogenous 1-acyl-lysophospholipids by at least two routes: (1) hydrolysis by a phospholipase a1; (2) acylation by an acyl-coa-dependent acyltransferase. in contrast to lysophospholipids, exogenous phospholipids are not rapidly metabolized by t. brucei. the acyltransferase (ec 2.3.1.23) converts exogenous 1-acyl lysophosphatidylcholine and exogenous acyl-coa to phosphatidylcholine and coa-sh. it is a membrane-bound enzyme and sho ... | 1988 | 2901036 |
| suppression of cyclical development of trypanosoma brucei brucei in glossina morsitans centralis by an anti-procyclics monoclonal antibody. | five hundred and sixty teneral male glossina morsitans centralis were fed, at the height of parasitaemia, on a goat infected with trypanosoma brucei brucei. thereafter, the tsetse were divided into 4 equal groups. group i was fed in vitro once weekly for 4 weeks and group ii twice weekly for 4 weeks on fresh defibrinated ox blood containing 2 mg/ml purified monoclonal antibody against t. b. brucei procyclics, while group iii was fed twice a week for 4 weeks on blood containing 2 mg/ml anti-t. vi ... | 1988 | 2901200 |
| further studies on the trypanosoma brucei group trypanosome, isolated from a patient infected in anger-didessa valley, west ethiopia, using the blood incubation infectivity test (biit). short communication. | | 1988 | 2901207 |
| a survey of aminotransferase activities in bloodstream trypanosoma brucei brucei. short communication. | | 1988 | 2901209 |
| [lymphocyte system and relative resistance of inbred mice to trypanosoma brucei brucei]. | the distribution of b-(ig+) and t-(thy1.2+, lyt1+, lyt2+) lymphocyte subsets in murine lymphoid organs was analysed by immunofluorescence (facs) on cell suspensions throughout a primary infection of c3h/he (susceptible) and cba/ca (subtolerant) inbred mice with metacyclic trypanosoma brucei brucei eatro 1125. a direct correlation was observed between (1) the level of first-peak parasitaemia, (2) its subsequent control by the host and (3) survival time. in the course of the infection, the overall ... | 1988 | 2905137 |
| serodiagnosis of african sleeping sickness in vervet monkeys by detection of parasite antigens. | sera of vervet monkeys experimentally infected with t. b. rhodesiense were examined using a double antibody sandwich elisa and procyclic agglutination trypanosomiasis test (patt) for the presence of circulating trypanosomal antigens and anti-procyclic surface antibodies, respectively. trypanosomal antigens were detected at 7 days post infection and remained at a detectable level thereafter during the infection. antigens were not detected in sera prior to experimental infection or at 26 days afte ... | 1988 | 2907259 |
| release of the variant surface glycoprotein during differentiation of bloodstream to procyclic forms of trypanosoma brucei. | investigations on the turnover of the membrane-form variant surface glycoprotein (mfvsg) of trypanosoma brucei during cultivation in vitro of the monomorphic variant clones mit at 1.2 and mit at 1.4 showed that bloodstream forms slowly released the surface coat into the medium (time required to decline to half the initial amount, t50% = 32 +/- 3 h). vsg appeared in the medium in its soluble form (svsg) which lacked the dimyristoylglycerol membrane anchor as judged by electrophoretic mobility and ... | 1989 | 2911281 |
| trypanosoma brucei contains two rna polymerase ii largest subunit genes with an altered c-terminal domain. | we have identified and cloned four trypanosomal rna polymerase largest subunit genes. here, we present the molecular analysis of two genes, trp4.8 and trp5.9. the sequence of these genes shows that they are almost identical to each other and indicates that they encode the largest subunit of rna polymerase ii. both genes contain a c-terminal extension that is clearly distinct from that of other eukaryotic rna polymerase ii genes, because it lacks the common tandemly repeated heptapeptide sequence ... | 1989 | 2917367 |
| trypanosoma brucei: frequent loss of a telomeric variant surface glycoprotein gene. | we have observed the loss of an inactive telomeric variant surface glycoprotein (vsg) gene that is located on a minichromosome in trypanosoma brucei. if this is due to gene conversion, it is the third "silent" gene conversion (i.e., one that does not produce an antigenic switch) detected in 19 antigenic switches of the istar 1 serodeme. this is surprisingly frequent since the immune response cannot select against the inactive gene. we estimate that 10(-1) to 10(-3) telomeric vsg gene conversions ... | 1989 | 2917631 |
| effect of in vitro cultivation on the stability of resistance of trypanosoma brucei brucei to diminazene, isometamidium, quinapyramine, and mel b. | a trypanosoma brucei brucei stock resistant to diminazene aceturate, isometamidium chloride, quinapyramine sulfate, and mel b was grown in vitro and its response to these drugs compared to that of a drug-sensitive trypanosome stock. there was little if any change of drug sensitivity after in vitro propagation as bloodstream forms for 120, 177, and 275 days and after in vitro transformation of bloodstream forms into procyclic, epimastigote, and finally metacyclic forms. drug resistance was stable ... | 1989 | 2918443 |
| in trypanosomes the homolog of the largest subunit of rna polymerase ii is encoded by two genes and has a highly unusual c-terminal domain structure. | we have isolated the genes encoding the largest subunit of all three classes of rna polymerase from trypanosoma brucei. while the pol ii largest subunit is encoded by a single gene in all organisms examined to date, trypanosomes contain two copies of the gene. both genes are expressed in the procyclic and bloodstream stages of the trypanosome life cycle. the two pol ii genes differ from one another in their coding sequences by 21 silent substitutions and 4 amino acid substitutions. in the core p ... | 1989 | 2924350 |
| the enzymes of the classical pentose phosphate pathway display differential activities in procyclic and bloodstream forms of trypanosoma brucei. | the specific activities of each of the enzymes of the classical pentose phosphate pathway have been determined in both cultured procyclic and bloodstream forms of trypanosoma brucei. both forms contained glucose-6-phosphate dehydrogenase (ec 1.1.1.49), 6-phosphogluconolactonase (ec 3.1.1.31), 6-phosphogluconate dehydrogenase (ec 1.1.1.44), ribose-5-phosphate isomerase (ec 5.3.1.6) and transaldolase (ec 2.2.1.2). however, ribulose-5-phosphate 3'-epimerase (ec 5.1.3.1) and transketolase (ec 2.2.1. ... | 1989 | 2924907 |
| a glycosomal protein (p60) which is predominantly expressed in procyclic trypanosoma brucei. characterization and dna sequence. | glycosomes are specialized organelles of trypanosomes which contain glycolytic enzymes as their major protein components in trypanosoma brucei bloodstream form. in the glycosomes of the insect form of t. brucei, additional enzyme activities are found but have not yet been ascribed to a particular protein molecule. in this study, we report the characterization of a 60-kda glycosomal protein (p60) encoded by a single copy gene which is transcribed into a mrna of 2.9 kilobases. the gene codes for a ... | 1989 | 2925689 |
| transcripts from the co-transposed segment of variant surface glycoprotein genes are in trypanosoma brucei polyribosomes. | in trypanosoma brucei the 5' proximal flanking sequences of a variant surface glycoprotein (vsg) gene, the co-transposed segment, are transcribed in a variant antigenic type- and stage-specific fashion along with the vsg gene. the precursor transcripts are subsequently processed to yield smaller transcripts from the co-transposed segment as well as the vsg mrna. these co-transposed segment transcripts are quite abundant, polyadenylated and contain the spliced leader sequence, all characteristics ... | 1989 | 2927445 |