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high level expression in escherichia coli of soluble, enzymatically active schistosomal hypoxanthine/guanine phosphoribosyltransferase and trypanosomal ornithine decarboxylase.the bacterial alkaline phosphatase (phoa) promoter and signal peptide have been used previously to control recombinant expression and secretion of eukaryotic proteins in escherichia coli. other reports have shown that this expression system can generate relatively modest levels of active hypoxanthine/guanine phosphoribosyltransferase (hprt; hypoxanthine phosphoribosyltransferase; imp:pyrophosphate phosphoribosyltransferase, ec 2.4.2.8), which carries part of the signal peptide but remains in the ...19912006185
inhibition of protein synthesis results in super-induction of procyclin (parp) rna levels.procyclin is an abundant surface antigen found exclusively on the procyclic forms of african trypanosomes. we are interested in the induction of procyclin gene expression during differentiation from bloodstream forms. we find that increased levels of procyclin rna are evident as early as 15 min after triggering differentiation. the increase in procyclin rna levels requires the temperature shift from 37 degrees c to 27 degrees c and is aided by addition of the tricarboxylic acid cycle intermediat ...19912011148
self-proteolysis of the cysteine proteinase, cruzipain, from trypanosoma cruzi gives a major fragment corresponding to its carboxy-terminal domain.the major cysteine proteinase (cruzipain) purified from trypanosoma cruzi epimastigotes catalyzes its own degradation in the presence of beta-mercaptoethanol, at 56 degrees c and ph 6. the reaction is affected by the same inhibitors which inhibit the azocaseinase activity, and yields a major 25-kda fragment, which contains carbohydrate, few, if any, aromatic amino acids, and presents a proline-rich n-terminus (gpgpxpep...), in addition to a number of small peptides, which can be isolated by reve ...19912011151
ultraviolet irradiation inhibits rna decay and modifies ribosomal rna processing in trypanosoma brucei.a known effect of ultraviolet radiation on transcription is the arrest of rna elongation. in trypanosoma brucei, we show that uv also inhibits rna decay, leading to specific accumulation of transcripts from the beginning of several transcription units. in addition, uv irradiation changes the pattern of ribosomal rna processing, probably by altering the order in which the non-coding spacers are excised. these effects are still observed on rna synthesized more than 2 h after irradiation, and do no ...19912011153
science and secrecy. 19912017252
phosphorylation differences among proteins of bloodstream developmental stages of trypanosoma brucei brucei.early in an infection the bloodstream forms of the african trypanosome trypanosoma brucei brucei are long, slender and rapidly dividing. later, non-dividing, short, stumpy forms may be found. in this report we described biochemical differences between the two parasite populations in the phosphorylation of their proteins in vitro. compared with the slender populations, the non-dividing stumpy forms of the parasites exhibit decreased phosphorylation of an 80 kda protein and enhanced phosphorylatio ...19912018486
crystallization and preliminary x-ray analysis of an intact soluble-form variant surface glycoprotein from the african trypanosome, trypanosoma brucei.the intact variant surface glycoprotein (vsg) iltat 1.24 from trypanosoma brucei has been crystallized. an amino-terminal domain of the protein comprising two thirds of the sequence had been crystallized previously after proteolytic digestion. now intact vsg crystals have been grown from 50 mm-mes (ph 6.5) containing 62% (w/v) saturated ammonium sulfate. the crystals are demonstrated to contain the intact vsg by h.p.l.c. gel filtration and reaction with an antibody to the inositol phosphate olig ...19912023242
trypanosoma brucei rhodesiense: characterisation of stocks from zambia, kenya, and uganda using repetitive dna probes.we have previously described a system for characterising the relationships between trypanosome stocks of the t.brucei group based on southern blotting with repetitive dna probes followed by cluster analysis of resultant banding patterns (g. hide et al. molec. bioch. parasitol. 39, 213-226, 1990). in this study, we extend this analysis to examine the relationships between trypanosome stocks isolated from major sleeping sickness foci in zambia, kenya, and uganda. we show that the trypanosome strai ...19912026217
galactocerebrosides are antigens for immunoglobulins in sera of an experimental model of trypanosomiasis in sheep.in an experimental model of human african trypanosomiasis in sheep inoculated with trypanosoma brucei brucei, we report an immunoglobulin reactivity towards central nervous system (cns) glycolipids. immunocharacterization of the glycolipid antigens was performed on thin-layer chromatography using peroxidase-labelled second antibody. an immunoreactivity against galactocerebroside antigens was observed in inoculated animals up to a dilution of 1:600 and was suppressed after immunoadsorption of ser ...19912027031
protein methylases in trypanosoma brucei brucei: activities and response to dl-alpha-difluoromethylornithine.protein methylases i, ii and iii were detected in extracts of trypanosoma brucei brucei, and characterized according to the specific amino substituent methylated. only protein methylase ii activity was elevated by difluoromethylornithine treatment of t. b. brucei, and hence this enzyme was characterized further. protein methylase ii transferred methyl groups from s-adenosyl-l-methionine (s-adomet) to the carboxyl residues of several protein substrates, exhibiting highest activity with histone vi ...19912033384
microtubules, tubulin, and microtubule-associated proteins of trypanosomes. 19912034124
recognition of a peroxisomal tripeptide entry signal by the glycosomes of trypanosoma brucei.trypanosomes compartmentalise the first 9 enzymes of glycolysis and glycerol metabolism in peroxisome-like microbodies known as glycosomes. the identity of the sequences that direct proteins into the glycosome has until now been uncertain. we show here that the peroxisomal tripeptide entry signal is sufficient to cause association of a bacterial enzyme with the glycosomes of trypanosoma brucei. however, it works less efficiently than the c-terminal 21 amino acids of trypanosome glycosomal phosph ...19912038359
porcine cerebral trypanosoma brucei brucei trypanosomiasis.this paper describes the investigation of a disease outbreak among 10 adult pigs in nsukka, anambra state, nigeria. prior to the investigation one sow died of the disease. trypanosomes were later detected in the blood of two of the nine pigs subsequently investigated. all the pigs were then treated with deep intramuscular injection of 8 mg/kg diminazene aceturate (berenil). thirty six days after treatment a boar and a sow relapsed with signs similar to the ones shown previously. further examinat ...19912038769
anion binding at the active site of trypanosomal triosephosphate isomerase. monohydrogen phosphate does not mimic sulphate.the three-dimensional structure of triosephosphate isomerase complexed with the competitive inhibitor so-4(2) was determined by x-ray crystallography to a resolution of 0.24 nm. a comparison with the native crystal structure, where so-4(2) is bound, revealed five changes: (a) a 0.10-nm shift of the anion-binding site; (b) a further closing of the flexible loop of the enzyme; (c) a 'swinging in' of the side chain of the catalytic glu, that is chi 1 changes from (+) to (-) synclinal; (d) an altere ...19912040290
the cytosolic and glycosomal isoenzymes of glyceraldehyde-3-phosphate dehydrogenase in trypanosoma brucei have a distant evolutionary relationship.trypanosoma brucei contains two isoenzymes for glyceraldehyde-3-phosphate dehydrogenase: one enzyme resides in a microbody-like organelle, the glycosome; the other is found in the cytosol. previously we have reported the characterization of the gene for the glycosomal enzyme [michels, p. a. m., poliszczak, a., osinga, k. a., misset, o., van beeumen, j., wierenga, r. k., borst, p. & opperdoes, f. r. (1986) embo j. 5, 1049-1056]. here we describe the cloning and analysis of the gene that codes for ...19912040303
the cytosolic and glycosomal glyceraldehyde-3-phosphate dehydrogenase from trypanosoma brucei. kinetic properties and comparison with homologous enzymes.the protozoan haemoflagellate trypanosoma brucei has two nad-dependent glyceraldehyde-3-phosphate dehydrogenase isoenzymes, each with a different localization within the cell. one isoenzyme is found in the cytosol, as in other eukaryotes, while the other is found in the glycosome, a microbody-like organelle that fulfils an essential role in glycolysis. the kinetic properties of the purified glycosomal and cytosolic isoenzymes were compared with homologous enzymes from other organisms. both trypa ...19912040304
nucleotide sequences of the six very small molecules of trypanosoma cruzi ribosomal rna. 19912041786
the in vitro differentiation of pleomorphic trypanosoma brucei from bloodstream into procyclic form requires neither intermediary nor short-stumpy stage.our studies on the in vitro differentiation of a pleomorphic trypanosoma brucei strain treu667 indicate that the parasite differentiates directly from long-slender into procyclic form when incubated in cunningham's medium at 26 degrees c. the intermediary and the short-stumpy bloodstream forms harvested from infected mice can also differentiate directly into procylic form in vitro with time courses similar to that for the long-slender form. thus, none of the three bloodstream forms appear to be ...19912052026
chemostat cultures of leishmania donovani promastigotes and trypanosoma brucei procyclic trypomastigotes. 19912052036
in vitro activity of organometallic complexes of ir, pt and rh on trypanosoma b. gambiense, t. b. rhodesiense and t. b. brucei.a series of organometallic drugs were tested in a photometric in vitro assay for trypanocidal activity against the three subspecies of the trypanosoma brucei group. trypanosoma b. rhodesiense, t. b. gambiense and t. b. brucei displayed a similar sensitivity pattern. the following ic50 values (drug concentration inhibiting decrease of extinction by 50%) could be determined: ircl6 (iv)-pentamidine (1.5 ng/ml), ircl6(iv)-ro15-0216 (10 micrograms/ml), ptbr6-metamidium (30 micrograms/ml), ptbr6(iv)-b ...19912052855
proofreading genes. a molecular editor makes sensible additions to rna. 19912052934
trypanosoma brucei: analysis of codon usage and nucleotide composition of nuclear genes. 19912055297
the crystal structure of the "open" and the "closed" conformation of the flexible loop of trypanosomal triosephosphate isomerase.triosephosphate isomerase has an important loop near the active site which can exist in a "closed" and in an "open" conformation. here we describe the structural properties of this "flexible" loop observed in two different structures of trypanosomal triosephosphate isomerase. trypanosomal triosephosphate isomerase, crystallized in the presence of 2.4 m ammonium sulfate, packs as an asymmetric dimer of 54,000 da in the crystallographic asymmetric unit. due to different crystal contacts, peptide 1 ...19912062827
the adaptability of the active site of trypanosomal triosephosphate isomerase as observed in the crystal structures of three different complexes.crystals of triosephosphate isomerase from trypanosoma brucei brucei have been used in binding studies with three competitive inhibitors of the enzyme's activity. highly refined structures have been deduced for the complexes between trypanosomal triosephosphate isomerase and a substrate analogue (glycerol-3-phosphate to 2.2 a), a transition state analogue (3-phosphonopropionic acid to 2.6 a), and a compound structurally related to both (3-phosphoglycerate to 2.2 a). the active site structures of ...19912062828
a rapid method purifies a glycoprotein of mr 145,000 as the ldl receptor of trypanosoma brucei brucei.the trypanosome ldl receptor has been isolated from bloodstream form and cultured insect-stage trypanosomes as a protein of mr 145,000, using a rapid purification procedure in the presence of a cocktail of protease inhibitors, whereas previously a polypeptide of mr 86,000 was purified as the ldl receptor. both the 145,000 and the 86,000 polypeptides are glycosylated and recognized by a monospecific antibody raised against the 86,000 species. this antibody inhibits ldl binding to the intact trypa ...19912069558
molecular genetics of antigenic variation.antigenic variation is one of the most effective strategies developed by parasites to escape immune destruction. it requires a large wardrobe of surface coats and mechanisms to exchange one coat for an unrelated one. the molecular principles of antigenic variation are now largely known in the bacterial species borrelia and neisseria and in the protozoa of the african trypanosome group and these three examples are discussed here by piet borst.19912069675
a soluble factor from trypanosoma brucei rhodesiense that prevents progression of activated human t lymphocytes through the cell cycle.african sleeping sickness is accompanied by a severe immunosuppression. as part of our efforts to examine the mechanisms by which this suppressive state is induced, we studied alterations in human t-lymphocyte function caused by trypanosoma brucei rhodesiense. to this end, we used an in vitro system in which phytohaemagglutinin (pha)-stimulated human peripheral blood mononuclear cells (pbmc) were cultured in a medium containing soluble, non-dialysable parasite products. we were able to demonstra ...19912071163
chromosome structure: dna nucleotide sequence elements of a subset of the minichromosomes of the protozoan trypanosoma brucei.the genome of the protozoan trypanosoma brucei contains a set of about 100 minichromosomes of about 50 to 150 kb in size. the small size of these chromosomes, their involvement in antigenic variation, and their mitotic stability make them ideal candidates for a structural analysis of protozoan chromosomes and their telomeres. we show that a subset of the minichromosomes is composed predominantly of simple-sequence dna, with over 90% of the length of the minichromosome consisting of a tandem arra ...19912072894
trypanosoma brucei brucei: antigenic stability of its ldl receptor and immunological cross-reactivity with the ldl receptor of the mammalian host.the rapid growth of trypanosoma brucei brucei in the blood and tissue fluids of vertebrates requires the receptor-mediated endocytosis of ldl from the host (coppens et al. 1987; gillett and owen 1987) and is slowed by a monospecific rabbit antiserum against the purified ldl receptor of the parasite. we have used this antiserum in combination with several well-characterized antigenic variants (originating from stock 427: mitat 1.1a, 1.3a, 1.4a, 1.5a, 1.5d, 1.8b) to examine whether the ldl recepto ...19921730273
extensive editing of both processed and preprocessed maxicircle cr6 transcripts in trypanosoma brucei.transcripts from several genes encoded in the trypanosoma brucei maxicircle genome are altered by posttranscriptional uridine insertion and deletion through a process called rna editing. we find that transcripts from the cr6 gene are extensively edited by addition of 132 uridines and deletion of 28 uridines to produce a fully edited mrna 47% larger than unedited mrna. two open reading frames (orfs) and their initiation and termination codons are created by editing of cr6 mrna. both orfs specify ...19921730639
characterization of an endopeptidase of trypanosoma brucei brucei.a soluble 80-kda endopeptidase has been isolated from trypanosoma brucei brucei. the enzyme, which has a pi 5.1, is optimally active at about ph 8.2 and has apparent pka values of 6.0 and greater than or equal to 10. it is inhibited by the serine protease inhibitor diisopropylfluorophosphate and by the serine protease mechanism-based inhibitor 3,4-dichloroisocoumarin. unexpectedly, the enzyme is inhibited by the cysteine protease inhibitor benzyloxycarbonyl-leu-lys-chn2 but not by the related di ...19921731636
mutual adjustment of glucose uptake and metabolism in trypanosoma brucei grown in a chemostat.the mutual adjustment of glucose uptake and metabolism in the insect stage of the protozoan parasite trypanosoma brucei was studied. t. brucei was preadapted in the chemostat to conditions in which either glucose or proline served as the major carbon and energy source. cells were grown and adapted to either energy or non-energy limitation at a low dilution rate (0.5 day-1) or a high dilution rate (1 day-1). the cells were then used in short- to medium-term uptake experiments with d-[14c]glucose ...19921735718
cysteine is an essential growth factor for trypanosoma brucei bloodstream forms.a modified cystine-free minimum essential medium has been used to address the question whether cysteine is an essential growth factor for bloodstream form trypanosomes or if its reducing power is sufficient to support parasite growth in axenic culture. bloodstream-form trypanosomes, taken either from freshly isolated infected mouse blood or from logarithmically growing axenic cultures were transferred to a medium containing 20% dialysed foetal calf serum, 10 microm bathocuproine sulphonate and 2 ...19921741014
correlation of autoantibody titres with central nervous system pathology in experimental african trypanosomiasis.cd-1 mice infected with the protozoan parasite trypanosoma brucei brucei developed few signs of central nervous system pathology associated with the invasion of the central nervous system by these parasites and did not survive beyond 5-6 weeks with deaths common before this time point. however, use of the trypanocidal drug diminazene aceturate (40 mg/kg), which fails to cross the blood-brain barrier, on day 21 post-infection led to the development of central nervous system pathology similar to t ...19921281824
direct isolation in vitro of trypanosoma brucei from man and other animals, and its potential value for the diagnosis of gambian trypanosomiasis.a recently described simple kit for isolating african trypanosomes in vitro (kivi) was tested further with blood samples from man and other animals in côte d'ivoire and république du congo. a high rate of success was achieved, with positive cultures being found 5-36 d after inoculation. the method was also of value in diagnosis. parasitaemia was initially detected by the haematocrit method; in addition, the mini-anion exchange column was used for human blood and lymph fluid from patients with sw ...19921287920
preliminary observations on the efficacy of mel cy (cymelarsan) in domestic animals infected with stocks of trypanosoma brucei brucei and t.b. evansi.the trypanocidal activity of an arsenical compound (rm 110; mel cy; cymelarsan) was evaluated against trypanosoma brucei brucei and t. brucei evansi in cultures, in goats and pigs. the trypanosome stocks used differed in their levels of susceptibility to cymerlarsan in an in vitro test, their ic50 values (drug concentration which inhibits growth by 50%) ranging from 4.8-5.1 nm for susceptible, and 26.9 nm for a resistant stock. goats infected with a susceptible t.b. evansi stock were cured after ...19921293725
genital lesions and histopathology of male guinea-pigs infected with trypanosomes.sixty adult male guinea-pigs were used to study the effect of trypanosoma brucei brucei and trypanosoma congolense infections on genitalia, testicles and reproductive capacity. both infections showed acute to chronic courses. t. b. brucei appeared more virulent than t. congolense. in both cases the infection periods significantly (p < 0.01) influenced resultant decrease in body and gonadal weight, testicular mass index and extent of lesion formation. histopathological lesions included mononuclea ...19921298022
structure of the complex between trypanosomal triosephosphate isomerase and n-hydroxy-4-phosphono-butanamide: binding at the active site despite an "open" flexible loop conformation.the structure of triosephosphate isomerase from trypanosoma brucei complexed with the competitive inhibitor n-hydroxy-4-phosphono-butanamide was determined by x-ray crystallography to a resolution of 2.84 a. full occupancy binding of the inhibitor is observed only at one of the active sites of the homodimeric enzyme where the flexible loop is locked in a completely open conformation by crystal contacts. there is evidence that the inhibitor also binds to the second active site of the enzyme, but ...19921304889
galactose-containing glycosylphosphatidylinositols in trypanosoma brucei.many eukaryotic surface glycoproteins, including the variant surface glycoproteins (vsgs) of trypanosoma brucei, are synthesized with a carboxyl-terminal hydrophobic peptide extension that is cleaved and replaced by a complex glycosylphosphatidylinositol (gpi) membrane anchor within 1-5 min of the completion of polypeptide synthesis. we have reported the purification and partial characterization of candidate precursor glycolipids (p2 and p3) from t. brucei. p2 and p3 contain ethanolamine-phospha ...19921309774
domain structure of u2 and u4/u6 small nuclear ribonucleoprotein particles from trypanosoma brucei: identification of trans-spliceosomal specific rna-protein interactions.maturation of mrnas in trypanosomes involves trans splicing of the 5' end of the spliced leader rna and the exons of polycistronic pre-mrnas, requiring small nuclear ribonucleoproteins (snrnps) as cofactors. we have mapped protein-binding sites in the u2 and u4/u6 snrnps by a combination of rnase h protection analysis, native gel electrophoresis, and cscl density gradient centrifugation. in the u2 snrnp, protein binding occurs primarily in the 3'-terminal domain; through u2 snrnp reconstitution ...19921310147
plasmodium falciparum and plasmodium chabaudi: characterization of glycosylphosphatidylinositol-degrading activities.merozoites of malaria parasites have a membrane-bound serine protease whose solubilization and subsequent activity depend on a parasite-derived glycosylphosphatidylinositol-phospholipase c (gpi-plc). the gpi-degrading activities from both plasmodium falciparum and plasmodium chabaudi have been characterized and partially purified by phenylboronate chromatography. they are membrane-bound, developmentally regulated, calcium-independent enzymes and as such they resemble gpi-plc of trypanosoma bruce ...19921317298
site of palmitoylation of a phospholipase c-resistant glycosylphosphatidylinositol membrane anchor.the site of palmitoylation of the phosphatidylinositol moiety of the glycosyl-phosphatidylinositol membrane anchor of trypanosoma brucei procyclic acidic repetitive protein was studied by using periodate oxidation. analysis of the products by g.c.-m.s. allowed the assignment of 40 and 60% of the palmitate to the 2-position and the 3-position respectively of the myo-inositol ring.19921318027
dna comparisons of trypanosoma evansi (indonesia) and trypanosoma brucei spp.two clones from separate isolates of trypanosoma evansi in indonesia were found by polymerase chain reaction (pcr) analyses to contain 3 different repeated nuclear dna sequences of trypanosoma brucei spp: the consensus sequence for a highly repetitive 177 base pairs and the gene repeats encoding procyclin and the spliced leader. in addition, the 994 bp minicircle sequence of one of the clones was determined, and pcr amplification primers specific for minicircles of t. evansi were identified that ...19921319564
a ribosomal rna gene promoter at the telomere of a mini-chromosome in trypanosoma brucei.the parasitic protozoan trypanosoma brucei has some hundred mini-chromosomes of 50-150 kb, which mainly consist of telomeric repeats, sub-telomeric repeats and internal 177-bp repeats. their primary function seems to be to expand the repertoire of non-transcribed sub-telomeric variant surface glycoprotein (vsg) genes. here we report that two of the smaller mini-chromosomes (55 and 60 kb) contain sequences homologous to the ribosomal rna gene promoter region. we have targeted by homologous recomb ...19921319572
an inositol phosphate glycan derived from a trypanosoma brucei glycosyl-phosphatidylinositol mimics some of the metabolic actions of insulin.some of the acute actions of insulin may be mediated by an enzyme-modulating inositol phosphate glycan, produced by the insulin-sensitive hydrolysis of glycosyl-phosphatidylinositol (gpi) that is structurally similar to a membrane protein anchor. an inositol glycan fragment from the structurally characterized trypanosoma brucei variant surface glycoprotein gpi anchor is evaluated for insulin-mimetic antilipolytic activity. the fragment specifically and dose-dependently inhibits isoproterenol-sti ...19921322896
inhibition of the glcnac transferase of the glycosylphosphatidylinositol anchor biosynthesis in african trypanosomes.a wide variety of eukaryotic membrane proteins are anchored to the cell surface by a covalent linkage to glycosylphosphatidylinositol. one of the best characterised examples is the variant surface glycoprotein of the protozoan parasite, trypanosoma brucei. the pathway for the formation of the glycosylphosphatidylinositol precursor has been previously described, with the first step being the transfer of glcnac, from udp-glcnac to endogenous phosphatidylinositol to form n-acetyl-glucosaminylphosph ...19921325903
the mitochondrion in bloodstream forms of trypanosoma brucei is energized by the electrogenic pumping of protons catalysed by the f1f0-atpase.bloodstream forms of trypanosoma brucei were found to maintain a significant membrane potential across their mitochondrial inner membrane (delta psi m) in addition to a plasma membrane potential (delta psi p). significantly, the delta psi m was selectively abolished by low concentrations of specific inhibitors of the f1f0-atpase, such as oligomycin, whereas inhibition of mitochondrial respiration with salicylhydroxamic acid was without effect. thus, the mitochondrial membrane potential is genera ...19921327770
native mrna editing complexes from trypanosoma brucei mitochondria.the aim of this study was to identify multicomponent complexes involved in kinetoplastid mitochondrial mrna editing. mitochondrial extracts from trypanosoma brucei were fractionated on 10-30% glycerol gradients and assayed for rnas and activities potentially involved in editing, including pre-edited mrna, guide rna (grna), endonuclease, terminal uridylyltransferase (tutase), rna ligase and grna-mrna chimera-forming activities. these experiments suggest that two distinct editing complexes exist. ...19921330537
cloning and characterization of the gene encoding trypanosoma cruzi dna topoisomerase ii.the gene encoding trypanosoma cruzi type ii topoisomerase (tctop2) was isolated from a genomic library with a heterologous probe corresponding to part of the trypanosoma brucei type ii topoisomerase (tbrtop2) gene. nucleotide sequencing of tctop2 showed that the gene consists of an open reading frame of 3696 nucleotides (1232 amino acids), predicting a polypeptide product of 138,413 da. comparison of the amino acid sequence with that of type ii topoisomerases from t. brucei (tbrtop2) and crithid ...19921331785
allelic polymorphism of the trypanosoma brucei polyubiquitin gene.we have characterized a second t. brucei polyubiquitin gene (ubb) that is highly similar in the coding and flanking regions to a previously described t. brucei polyubiquitin gene (uba). however, ubb differs from uba in 2 respects: (1) the predicted carboxy-terminal amino acid of ubb is methionine, as opposed to leucine in uba, and (2) ubb contains approximately 13 ubiquitin repeats, as opposed to approximately 30 repeats in uba. in southern blots of intact t. brucei dna separated by pulsed field ...19921331786
the nucleotide sequence of the variable region in trypanosoma brucei completes the sequence analysis of the maxicircle component of mitochondrial kinetoplast dna.the nucleotide sequence of two non-contiguous dna fragments of 4.0 and 2.2 kb, respectively, of the kinetoplast maxicircle of trypanosoma brucei brucei eatro strain 427 has been determined, completing the sequence analysis of the so-called variable region (see also de vries et al., 1988, mol. biochem. parasitol. 27, 71-82). analysis of the entire 8-kb variable region sequence revealed the presence of a 5.2-kb cluster of imperfect, tandemly repeated sequences, flanked by dna of unique sequence. b ...19921336570
parasitaemia and clinical manifestations in trypanosoma brucei infected dogs.four dogs were infected with trypanosoma brucei (mkar strain) while another four were used as uninfected controls. two of the dogs showed acute disease and died in the first wave of parasitaemia on days 7 and 8 post infection (pi) while the other two died from the sub-acute disease on days 24 and 28 pi corresponding to the second wave of parasitaemia. in the first wave of parasitaemia there was a sharp decrease in the packed cell volume, red blood cell, haemoglobin, total leucocytes, eosinophil, ...19921339994
erythrocyte response to trypanosoma brucei in experimentally infected dogs.trypanosoma brucei infection produced an acute and fatal disease in nigerian mongrel dogs due to a rapidly developing anaemia. infected dogs responded with increased reticulocytosis, which was not sustained with chronicity. in comparison the response to artificially-induced haemolytic anaemia was progressive, marked and sustained. the anaemia of t. brucei infection of dogs was either normocytic normochromic in acute infection or microcytic normochromic in chronic infection. artificially-induced ...19921339995
some plasma biochemical changes in experimental trypanosoma brucei infection of sokoto red goats.plasma biochemical changes were studied for 8 consecutive weeks in sokoto red goats experimentally infected by intravenous route injection of 1.6 x 10(7) trypanosoma brucei. the strain 8/18 was highly infective. the mean packed cell volume significantly decreased from 1 to 8 weeks post-infection (pi) at p < 0.05. during this period, the mean plasma total bilirubin concentrations significantly increased (p < 0.05). the mean plasma direct and indirect bilirubin concentrations significantly increas ...19921339997
a novel microtubule-binding motif identified in a high molecular weight microtubule-associated protein from trypanosoma brucei.the major component of the cytoskeleton of the parasitic hemoflagellate trypanosoma brucei is a membrane skeleton which consists of a single layer of tightly spaced microtubules. this array encloses the entire cell body, and it is apposed to, and connected with, the overlying cell membrane. the microtubules of this array contain numerous microtubule-associated proteins. prominent among those is a family of high molecular weight, repetitive proteins which consist to a large extent of tandemly arr ...19921348252
subcurative chemotherapy and fatal post-treatment reactive encephalopathies in african trypanosomiasis.the treatment of late-stage african sleeping sickness in man is often complicated by a post-treatment reactive encephalopathy. the bases of this pathological reaction was investigated in a mouse model of african trypanosomiasis. subcurative treatment with diminazene aceturate, which did not clear parasites from the central nervous system, resulted in a post-treatment meningoencephalitis similar to that seen in man. by contrast, a curative regimen of melaminylthioarsenite and 5-nitroimidazole, wh ...19921348799
trisomy and chromosome size changes in hybrid trypanosomes from a genetic cross between trypanosoma brucei rhodesiense and t. b. brucei.further analysis of hybrid clones from an experimental cross of trypanosoma brucei rhodesiense 058 and t. b. brucei 196 shows 2 of the hybrid clones to have dna contents about 1.5 times parental values. this represents over 40,000 kb of extra dna. comparison of the molecular karyotypes of parental and progeny trypanosomes shows that the bulk of the extra dna constitutes chromosomes greater than 1 mb in size, although a small proportion can be accounted for by an increased number of mini-chromoso ...19921349422
mass spectrometry of mrna cap 4 from trypanosomatids reveals two novel nucleosides.synthesis of mrna in kinetoplastid protozoa involves the process of trans-splicing, in which an identical 39-41-nucleotide (depending on the species) mini-exon is placed at the 5' end of mature mrnas. the mini-exon sequence is highly conserved among all members of the kinetoplastida, nucleotides 1-6 being identical in the four genera so far examined. prior to trans-splicing, the mini-exon donor rna is capped by the addition of a (5'-5') triphosphate-linked 7-methylguanosine, followed by modifica ...19921349605
transcript-specific developmental regulation of polyadenylation in trypanosoma brucei mitochondria.transcripts from many mitochondrial genes in kinetoplastids are heterogeneous in size, often occurring as 2 distinct size classes, but this cannot be accounted for by rna editing alone. analyses of transcripts from 6 mitochondrial genes of trypanosoma brucei indicates that the size variation is due to poly(a) tail length. a larger fraction of cyb, coi and coii transcripts have longer poly(a) tails in procyclic than in bloodstream forms. these transcripts are also more abundant in the procyclic f ...19921352374
the in vitro efficacy of reuterin on the culture and bloodstream forms of trypanosoma brucei brucei.1. the in vitro effects of a new antibiotic, reuterin, were determined for culture and bloodstream forms of trypanosoma brucei brucei. it inhibited growth of the culture forms and motility, viability and dna and protein syntheses of culture and bloodstream forms. 2. reuterin administered with inhibitors of ribonucleotide reductase (hydroxyurea and deoxyadenosine) was synergistic only for growth of the culture form of the parasite. 3. reuterin was trypanocidal at lower doses than dfmo, mel b, and ...19921354096
sequential infection of tsetse flies with trypanosoma congolense and trypanosoma brucei.the question whether tsetse flies can be experimentally infected with more than one trypanosome species or strain by sequential feeding was investigated using dna probe technology to identify directly the small numbers of trypanosomes in the fly gut. bloodstream form trypanosomes of trypanosoma congolense or t. brucei ssp. were used for initial infection, followed by sequential feeds using either t. congolense or t. brucei ssp. midgut trypanosome populations were subsequently analysed by hybridi ...19921356306
influence of d(+)-glucosamine on infection rates and parasite loads in tsetse flies (glossina spp.) infected with trypanosoma brucei.teneral glossina morsitans centralis, g. m. morsitans and g. pallidipes were infected with three different clones of trypanosoma brucei in blood containing d(+)-glucosamine, an inhibitor of tsetse midgut lectin. on average, 5 days of d(+)-glucosamine treatment tripled infection rates, without affecting the proportion of infections that matured. total infection rates were equal in males and females, but twice as many infections matured in males. counts of parasites in the guts and salivary glands ...19921359749
vector competence of glossina pallidipes and g. morsitans centralis for trypanosoma vivax, t. congolense and t. b. brucei.vector competence of glossina pallidipes for pathogenic trypanosoma species was compared to that of g. morsitans centralis. cattle or goats were the hosts used to infect teneral tsetse, rabbits were used to maintain tsetse which were dissected on day 30. mean infection rates of g. pallidipes and g. m. centralis by t. vivax isolated from a cow in kenya were respectively 39.5 +/- 8.9% and 32.1 +/- 10.3% whilst for t. vivax isolated from a cow in nigeria, they were 30.0 +/- 7.5% and 19.8 +/- 4.3%. ...19921359753
structural differences between the chromatin of procyclic trypanosoma brucei brucei and of higher eukaryotes as probed by immobilized trypsin.soluble chromatin of trypanosoma brucei brucei procyclic culture forms was submitted to digestion with free or immobilized trypsin. digestion with trypsin in salt solutions of low and high ionic strengths generated characteristic sets of limit histone peptides. after incubation of chromatin with immobilized trypsin in a solution of low ionic strength, histones were not degraded, whereas a selective proteolysis occurred at 50 mm nacl. histones a and d, which correspond to h3 and h4 of higher euka ...19921359762
application of a monoclonal antibody-based antigen detection enzyme-linked immunosorbent assay (antigen elisa) for field diagnosis of bovine trypanosomiasis at nguruman, kenya.a monoclonal antibody-based, enzyme immunoassay (antigen elisa) for the detection of species-specific invariant antigens of trypanosoma congolense, t. vivax or t. brucei in the serum of infected animals was evaluated as a means of diagnosis using bovine field sera from a trypanosomiasis endemic area, nguruman, kenya. circulating trypanosome antigens were detected in 126 (96.2%) of 131 serum samples from animals with parasitologically confirmed diagnosis: 74.8% were positive for antigens of two o ...19921360196
neisserial surface variation: how and why?neisseria gonorrhoeae exhibits striking variability in several of its surface components (pili, opa proteins and lipooligosaccharide) in vivo and in vitro. such flagrant variation of this mucosal pathogen's surface components contrasts sharply with changes in single surface components of blood-borne trypanosomes and borreliae. despite these differences, similar molecular events are sometimes involved.19921360853
glycosyl phosphatidylinositol-specific phospholipase c of trypanosoma brucei: expression in escherichia coli.glycosyl phosphatidylinositol-specific phospholipase c (gpi-plc) from trypanosoma brucei cleaves the glycosyl phosphatidylinositol (gpi) anchor of the trypanosome variant surface glycoprotein (vsg) and other gpi structures. we have expressed this enzyme in escherichia coli, using a protocol designed to produce the native enzyme rather than a fusion protein. we have purified large amounts of gpi-plc from e. coli membranes, using a single step immunoaffinity technique. the expressed enzyme is iden ...19921362451
evolution of the retrotransposons trs/ingi and of the tubulin genes in trypanosomes.the african trypanosomes have genomes of high plasticity, as demonstrated for instance by their ability to shuffle their genes around, coding for variant-specific surface glycoproteins (vsgs). another indication of their genome plasticity is the presence of multiple retro-elements. the retrotransposon-like element trs/ingi is present in many copies in the genome of trypanosomes. one particular derivative of trs/ingi, called tubis, had previously been found to interrupt a tubulin gene in a partic ...19921363182
some kinetic properties of pyruvate kinase from trypanosoma brucei.we have studied the kinetics of the allosteric interactions of pyruvate kinase from trypanosoma brucei. the kinetics for phosphoenolpyruvate depended strongly on the nature of the bivalent metal ions. pyruvate kinase activated by mg2+ had the highest catalytic activity, but also the highest s0.5 for phosphoenolpyruvate, while the opposite was true for pyruvate kinase activated by mn2+. the reaction rates of mg(2+)-pyruvate kinase and mn(2+)-pyruvate kinase were clearly allosteric with respect to ...19921371328
the parp and vsg genes of trypanosoma brucei do not resemble rna polymerase ii transcription units in sensitivity to sarkosyl in nuclear run-on assays.addition of the ionic detergent n-lauroylsarcosine (sarkosyl) affects the efficiency of transcription of genes of the protozoan trypanosoma brucei in nuclear run-on assays. transcription of the parp (procyclin or procyclic acidic repetitive protein), variant cell surface glycoprotein (vsg) and ribosomal rna (rrna) genes was resistant or increased after addition of sarkosyl. in contrast, the transcription of seven protein coding house keeping genes and the mini-exon donor rna (medrna) genes was c ...19921371345
developmental variation of glycosylphosphatidylinositol membrane anchors in trypanosoma brucei. in vitro biosynthesis of intermediates in the construction of the gpi anchor of the major procyclic surface glycoprotein.the african trypanosome, trypanosoma brucei, expresses two abundant stage-specific glycosylphosphatidylinositol (gpi)-anchored glycoproteins, the procyclic acidic repetitive protein (parp or procyclin) in the procyclic form, and the variant surface glycoprotein (vsg) in the mammalian bloodstream form. the gpi anchor of vsg can be readily cleaved by phosphatidylinositol (pi)-specific phospholipase c (pi-plc), whereas that of parp cannot, due to the presence of a fatty acid esterified to the inosi ...19921371998
molecular biology of african trypanosomes: development of new strategies to combat an old disease.african trypanosomes are protozoan parasites that cause a number of diseases of man and domesticated animals in large regions of sub-saharan africa. the diseases have proven to be particularly difficult to prevent or to effectively treat due to features of both the trypanosome and the insect vector, the tsetse fly. the habitat of the tsetse and its resistance to insecticides have rendered vector control efforts ineffective. attempts to develop a vaccine against the african trypanosomes has been ...19921373267
guide rnas for transcripts with developmentally regulated rna editing are present in both life cycle stages of trypanosoma brucei.rna editing of several mitochondrial transcripts in trypanosoma brucei is developmentally regulated. the cytochrome b and cytochrome oxidase ii mrnas are edited in procyclic-form parasites but are primarily unedited in bloodstream forms. the latter forms lack the mitochondrial respiratory system present in procyclic forms. editing of the nadh dehydrogenase 7 (nd7) and nd8 transcripts is also developmentally regulated but occurs preferentially in bloodstream forms. other transcripts, cytochrome o ...19921373804
maxicircle cr1 transcripts of trypanosoma brucei are edited and developmentally regulated and encode a putative iron-sulfur protein homologous to an nadh dehydrogenase subunit.the maxicircle of trypanosoma brucei encodes components of the mitochondrial oxidative phosphorylation system, as do other mitochondrial dnas, but maxicircle gene identification is complicated by extensive editing of some transcripts. we found that transcripts from the cr1 region were extensively edited, as are other transcripts from maxicircle regions which exhibit strong g versus c strand bias. editing added 259 uridines and removed 46 uridines to produce an approximately 574-nucleotide mature ...19921373807
in vitro guide rna/mrna chimaera formation in trypanosoma brucei rna editing.the post-transcriptional processing of various mitochondrial transcripts in kinetoplastids, krna editing, adds and removes uridines, producing mature messenger rnas. this editing seems to be directed by 'guide' rnas (grnas) which are complementary to portions of the mature message. the editing mechanism has been proposed to entail transesterification. detection of chimaeric grna-mrna molecules, intermediates predicted by transesterification, support this model. we report here the in vitro format ...19921374163
in vivo assessment of drug sensitivity of african trypanosomes using the akinetoplastic induction test.following treatment of mice infected with trypanosoma congolense or t brucei brucei with various doses of isometamidium chloride or diminazene aceturate, the induction of akinetoplastic (ak) forms was observed in the trypomastigotes of both species within 10 hours of drug administration. the levels of ak-induction were closely correlated with the levels of resistance to each compound found using a standard in vivo drug assay in mice. in general, ineffective doses of either compound conferred ak- ...19921374928
specific cleavage of pre-edited mrnas in trypanosome mitochondrial extracts.rna editing in trypanosoma brucei is a posttranscriptional processing event that results in the addition and deletion of uridine residues within several mitochondrial mrnas. we have examined reactions involving pre-edited precursor rnas in vitro. in this study, we report specific cleavage of pre-edited cytochrome b (cyb), cytochrome oxidase subunit ii (coii), and cytochrome oxidase subunit iii (coiii) mrnas when incubated with t. brucei mitochondrial extracts. the pre-edited cyb rna was cleaved ...19921375322
surface epitope variation via mosaic gene formation is potential key to long-term survival of trypanosoma brucei.trypanosoma brucei evades the immune response of its mammalian host by antigenic variation in the major surface antigen (the variable surface glycoprotein or vsg). we examined the generation of diversity in 4 in vivo-derived antigenically related clones of t. brucei by sequencing vsg cdna from each of the 4 clones and all 5 related genomic copies in the watat 1.1 progenitor organism. each expressed vsg gene was a different mosaic of basic copy genes; 3 were complex mosaics consisting of multiple ...19921380125
trypanosoma brucei mitochondrial ribosomal rna synthesis, processing and developmentally regulated expression.the steady-state levels of the mitochondrial ribosomal rnas of trypanosoma brucei are repressed in the early bloodstream developmental stage of the parasite and accumulate approximately 30-fold during differentiation to the stage found in the midgut of the insect vector. in order to determine the mechanism regulating this developmental process, we have examined the transcription and processing of the 9s and 12s mitochondrial rrnas of t. brucei. a short-lived rna was detected in pulse labeling ex ...19921381496
identification of nuclear encoded precursor trnas within the mitochondrion of trypanosoma brucei.rnas that function in mitochondria are typically encoded by the mitochondrial dna. however, the mitochondrial trnas of trypanosoma brucei are encoded by the nuclear dna and therefore must be imported into the mitochondrion. it is becoming evident that rna import into mitochondria is phylogenetically widespread and is essential for cellular processes, but virtually nothing is known about the mechanism of rna import. we have identified and characterized mitochondrial precursor trnas in t. brucei. ...19921385429
nitric oxide mediates suppression of t cell responses in murine trypanosoma brucei infection.african trypanosomes induce a generalized state of immunosuppression in their mammalian hosts. one characteristic of this is a suppression of lymphocyte responses to mitogen, which is mediated by suppressor macrophages. we investigated the involvement of nitric oxide in this phenomenon. both peritoneal and splenic cell cultures from infected mice released nitrite and this was inhibitable by ng-monomethyl l-arginine (l-nmma). the release of nitrite correlated with suppressed splenic t cell prolif ...19921396977
immunological characterization and intracellular localization of trans-spliceosomal small nuclear ribonucleoproteins in trypanosoma brucei.polyclonal antibodies were raised against purified protein components of the u2 small nuclear ribonucleoprotein (snrnp) from trypanosoma brucei. through immunoblot and immunoprecipitation analyses three antisera were characterized that reacted specifically with u2 snrnp proteins of molecular weights 40,000 (anti-40k) and 16,500 (anti-16.5k), and with each of four proteins of molecular weights 14,000, 12,500, 10,000, and 8,500 (anti-cp). anti-40k antibodies specifically immunoprecipitated the u2 ...19921400334
trypanosoma brucei spliced-leader rna methylations are required for trans splicing in vivo.the trypanosoma brucei spliced leader (sl) rna donates its 5' leader sequence to all nuclear pre-mrnas via trans rna splicing. the sl rna is a small-nuclear u rna-like molecule which is present in the cell as part of a small ribonucleoprotein particle. however, unlike the trimethylguanosine-capped small nuclear u rnas, the sl rna has a highly modified 5' terminus containing an m7g cap and methylations on the first four transcribed nucleotides. here, we show that incubation of procyclic-form t. b ...19921406666
inhibitory effect of trypanosoma brucei brucei on glossina morsitans midgut trypsin in vitro.the ability of trypanosoma brucei brucei to inhibit trypsin or trypsin-like enzymes in crude midgut homogenates of glossina morsitans morsitans was studied in vitro. the isolated parasites caused a concentration-dependent decrease in midgut trypsin activity. furthermore, trypanosomes lysed by repeated freeze-thawing had a similar effect on trypsin activity. in both cases, the inhibition by either intact or lysed parasites was partial as revealed by dixon plots. similarly, trypanosome membrane pr ...19921409526
developmental regulation of nuclear gene expression in trypanosoma brucei. 19921410447
the response of pigs experimentally infected with trypanosoma brucei to isometamidium chloride therapy and the relation to nutrition.growing pigs were placed on feeds with high (group a), medium (b) and low (c) dietary energy and were infected with a virulent stock of t. brucei. eight weeks later, the infected pigs were treated with isometamidium chloride at 1 mg/kg live weight and all pigs were subsequently placed on a high energy diet to investigate their response to therapy. clearance of t. brucei from blood was completed 72h after treatment. there was no evidence of relapsed infection up to eight weeks after treatment. re ...19921413445
effects of infection with trypanosoma brucei brucei on different trimesters of pregnancy in ewes.the effects of trypanosoma brucei brucei infection during the first, second or third trimesters of pregnancy in 13 ewes were studied. all infected ewes were anaemic with the anaemia being most severe, moderate and least in ewes infected in the second, third and first trimesters, respectively. weight loss occurred in all infected ewes but was most severe in ewes infected in the third trimester. three of the four ewes infected in the first trimester died without aborting while one aborted and late ...19921413452
mechanisms underlying trypanosome-elicited immunosuppression.t-cell proliferative responses of lymph node cells are profoundly suppressed during experimental infections of mice with trypanosoma brucei. the active suppression of lymph node t-cell proliferative responses is attributed to the coexistence of at least two unlinked suppressive mechanisms that block different t-cell regulatory steps and operate through different effector mechanisms. the generation of prostaglandin-producing macrophages is entirely responsible for the suppression of il-2 producti ...19921417167
the predominant calcimedins from trypanosoma brucei comprise a family of flagellar ef-hand calcium-binding proteins.the cellular complement of calcimedins was identified in trypanosoma brucei by ca(2+)-dependent association with phenyl-sepharose. predominant calcimedins with molecular mass of 23-26 kda and 44 kda, along with minor calcimedins of 96, 120 and 230 kda, were obtained. the trypanosome calcimedins were unrelated to vertebrate annexins, based upon antibody cross-reactivity and an inability to associate in a ca(2+)-dependent way with phospholipid vesicles comprised of phosphatidylserine or phosphatid ...19921417772
nitric oxide-mediated cytostatic activity on trypanosoma brucei gambiense and trypanosoma brucei brucei.macrophages collected from bcg-infected mice or exposed in vitro to interferon-gamma plus lipopolysaccharide developed a cytostatic activity on trypanosoma brucei gambiense and trypanosoma brucei brucei. this trypanostatic activity of activated macrophages was inhibited by addition of n-monomethyl-l-arginine, an inhibitor of the l-arginine-nitric oxide (no) metabolic pathway, indicating a role for no as the effector molecule. contrary to trypanosomes treated with n2gas, trypanosomes treated with ...19921426137
an enzyme-linked immunosorbent assay (elisa) for the detection of trypanosomal antigens in goat serum using a monoclonal antibody.an igm murine monoclonal antibody (mab) tea 1/23.3.4.6 raised against circulating trypanosome antigens was used in a sandwich elisa to assay trypanosomal antigens in a trypanosome lysate preparation and in sera from goats infected with trypanosoma brucei evansi. as little as 1.25 ug/ml of trypanosomal antigen could be detected by this assay. following infection, trypanosomal antigens were first detected in goat serum 24 hours after the intravenous (i/v) or 6 days after the intramuscular (i/m) in ...19921430240
astrocyte activation correlates with cytokine production in central nervous system of trypanosoma brucei brucei-infected mice.during the late-stage disease associated with human african trypanosomiasis, caused by infection with either trypanosoma gambiense or t. rhodesiense, parasites invade the central nervous system (cns), eventually leading to development of cns pathology. this can be exacerbated by subcurative chemotherapy. the mechanisms through which the inflammatory processes within the cns are controlled remain unclear.19921434541
a procyclin-associated gene in trypanosoma brucei encodes a polypeptide related to esag 6 and 7 proteins.the procyclin genes of trypanosoma brucei encode a family of glycoproteins expressed on the surface of procyclic forms of the parasite. these genes are present at different loci in tandem arrays of two or three copies depending on the strain. it has previously been shown that procyclin genes are transcribed from a promotor immediately upstream of the first procyclin gene in each cluster by an rna polymerase that is resistant to high levels of alpha-amanitin. here we show that additional genes, w ...19921435865
the electrochemical proton gradient in the bloodstream form of trypanosoma brucei is dependent on the temperature.the membrane potential and ph gradient over the plasma membrane of the protozoan parasite trypanosoma brucei were measured with radioactive indicators in combination with the silicone oil centrifugation technique over a range of temperatures. at 37 degrees c a small membrane potential and ph gradient of similar magnitude, but of opposite polarity, were measured. the resulting electrochemical proton gradient was almost zero. however, when the temperature was lowered from 37 degrees c to 22 degree ...19921435870
the translation initiation site of recombinant trypanosoma brucei ornithine decarboxylase varies with different promoters.expression of the trypanosoma brucei ornithine decarboxylase (odc) gene in escherichia coli behind the lambda phage pr promoter led to the production of a recombinant enzyme having the same subunit molecular weight as the native enzyme [4]. however, when the same gene is expressed behind the tac promoter or the phoa promoter, the odcs produced by the transformed e. coli have subunit molecular weights approximately 2 kda higher than that of the native enzyme. amino terminal sequencing of the reco ...19921435879
sequence differences between histones of procyclic trypanosoma brucei brucei and higher eukaryotes.four histones, a, b, c, d from procyclic trypanosoma brucei brucei, which show similarities with the amino acid composition of the core histones h3, h2a, h2b and h4, were isolated and cleaved with endoproteinase glu-c. the fragments were separated by fplc reversed phase chromatography and a subset of the fragments (a5, a9, b6, c8, d3, d9, d11) was subjected to sequence analysis. a 54-71% identity was found in the sequences of the fragment c8 and the c-terminal half of h2b and of three fragments ...19921437281
histone-dna interactions in the chromatin of procyclic trypanosoma brucei brucei.the dissociation of histone proteins a-d from the chromatin of trypanosoma brucei brucei procyclic culture forms was investigated by removing the proteins from the dna by centrifugation of soluble chromatin through isokinetic sucrose gradients in the presence of nacl. the dissociation of the t. b. brucei histones was compared with that of their higher-eukaryote counterparts h3, h2a, h2b and h4. all four histones of t. b. brucei remained bound to the dna at 500 mm nacl, were partially released at ...19921438135
changes in atrial natriuretic factor and plasma renin activity in dogs infected with trypanosoma brucei.when beagle dogs were infected with trypanosoma brucei, a marked reduction in the plasma concentration of atrial natriuretic factor (anf) occurred in the terminal stage of the disease during weeks 3 and 4. at the same time there was an increase in plasma renin activity (pra) after infection. ultrastructural studies of the atria of these dogs demonstrated a reduction in anf granules. the changes in anf and pra occurred in association with severe pancarditis and the development of heart failure. b ...19921438145
glycosome assembly in trypanosomes: variations in the acceptable degeneracy of a cooh-terminal microbody targeting signal.trypanosomes compartmentalize most of their glycolytic enzymes in a peroxisome-like microbody, the glycosome. the specificity of glycosomal targeting was examined by expression of chloramphenicol acetyltransferase fusion proteins in trypanosomes and monkey cells. compartmentalization was assessed by cell fractionation, differential detergent permeabilization, and immunofluorescence. the targeting signal of trypanosome phosphoglycerate kinase resides in the cooh-terminal hexapeptide, nrwssl; a ba ...19921447292
molecular characterization of the trypanothione reductase gene from crithidia fasciculata and trypanosoma brucei: comparison with other flavoprotein disulphide oxidoreductases with respect to substrate specificity and catalytic mechanism.trypanothione reductase belongs to the family of flavoprotein disulphide oxidoreductases that include glutathione reductases, dihydrolipoamide dehydrogenases and mercuric reductases. trypanothione reductase and its substrate, trypanothione disulphide, are unique to parasitic trypanosomatids responsible for several tropical diseases. the crystal structure of the enzyme from crithidia fasciculata is currently under investigation as an aid in the design of selective inhibitors with a view to produc ...19921453951
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