Publications

genetic control of antigenic variation in trypanosomes.		1985	2411332
macrophages as mediators of immunosuppression in murine african trypanosomiasis.		1985	2411475
telomeric reciprocal recombination as a possible mechanism for antigenic variation in trypanosomes.	in african trypanosomes, antigenic variation is achieved through differential gene activation, with one antigen gene being expressed at a time among a large collection of antigen-specific sequences. transcription of the antigen gene always takes place in a telomere, but different telomeres can alternatively act as the expression site. telomeric antigen genes can be expressed without apparent dna rearrangement, but they can also, like non-telomeric genes, have access to the telomeric expression s ...	1985	2412122
unusual rna polymerase content of trypanosoma brucei nuclei.	nuclei were isolated from bloodstream forms of trypanosoma brucei by nitrogen cavitation and sedimentation through percoll density gradients. transcription studies with these nuclei in vitro demonstrated features not seen with other eukaryotes: rna synthesis was much greater in the presence of mn2+ than with mg2+ and was sensitive to high concentrations (10-100 micrograms/ml) of alpha-amanitin at all salt concentrations tested (25-300 mm ammonium sulphate). rna polymerase extracted from nuclei b ...	1985	2413850
antibodies to calmodulin during experimental trypanosoma brucei rhodesiense infections in rabbits.	calmodulin is an intracellular ca2+ receptor protein which regulates a wide variety of enzymatic processes in eukaryotic cells examined in detail. native calmodulin is not antigenic in rabbits because of its small size, high degree of amino acid sequence conservation and hydrophobicity. african trypanosomes contain a novel calmodulin which is structurally distinct from bovine brain and tetrahymena calmodulins. in the present study, we examine the antibody response towards these calmodulins durin ...	1985	2414212
comparative structural analysis of calmodulins from trypanosoma brucei, t. congolense, t. vivax, tetrahymena thermophila and bovine brain.	calmodulin is an intracellular calcium receptor protein utilized extensively by eukaryotic cells to mediate responsiveness to calcium signals. the present study evaluates the effects on protein structure of amino acid substitutions in trypanosome calmodulin. calmodulin conformation, hydrophobicity and antigenic determinants are compared among trypanosoma brucei, trypanosoma congolense, trypanosoma vivax, tetrahymena thermophila and bovine brain. trypanosome calmodulin differs from brain and tetr ...	1985	2417117
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
transcription of a transposed trypanosome surface antigen gene starts upstream of the transposed segment.	the non-telomeric variant surface glycoprotein (vsg) genes in trypanosoma brucei are activated by a duplicative transposition to a telomeric expression site. we have determined the 5' end of the transposed segment of the gene for vsg 117 and infer from comparison with similar data obtained by others that the crossover can occur at variable positions within short repeats present upstream of this gene and in the expression site. we have analysed nascent and steady state transcripts of the transpos ...	1985	3004950
topogenesis of microbody enzymes: a sequence comparison of the genes for the glycosomal (microbody) and cytosolic phosphoglycerate kinases of trypanosoma brucei.	to determine how microbody enzymes enter microbodies, we are studying the genes for cytosolic and glycosomal (microbody) isoenzymes in trypanosoma brucei. we have found three genes (a, b and c) coding for phosphoglycerate kinase (pgk) in a tandem array in t. brucei. gene b codes for the cytosolic and gene c for the glycosomal isoenzyme. genes b and c are 95% homologous, and the predicted protein sequences share approximately 45% amino acid homology with other eukaryote pgks. the microbody isoenz ...	1985	3004970
expression of a minichromosomal variant surface glycoprotein gene in trypanosoma brucei.	african trypanosomes contain numerous variant surface glycoprotein (vsg) genes, but express only one at a time. when different vsg genes are activated by gene duplicative or non-duplicative mechanisms, antigenic variation occurs. although transcriptionally inactive vsg genes can have either an intra-chromosomal or a telomeric location, all expressed vsg genes so far examined are telomeric. some vsg genes are located on minichromosomes of approximately 100 kilobases (kb), but all those thus far d ...	1985	2578631
antigenic variation in clones of trypanosoma brucei grown in immune-deficient mice.	we have produced monoclonal antibodies against six variant surface glycoproteins from early variant antigen types (vats) of the istar 1 serodeme of trypanosoma brucei brucei. we have used these in fixed cell immunofluorescence assays to follow the vat composition of populations of each early vat when passaged through irradiated mice. the istat 1.a and 1.7a populations were stable for more than 30 days (approximately 150 generations), but 1.1a, 1.3a, 1.5a, and 1.11a all changed to 1.a within this ...	1985	2579027
genetics of resistance to the african trypanosomes. v. qualitative and quantitative differences in interferon production among susceptible and resistant mouse strains.	the induction of interferon (ifn) was examined in different inbred mouse strains infected with trypanosoma brucei rhodesiense. relatively susceptible c3heb/fej mice that do not exhibit variant-specific immunity or control parasitemia did not exhibit detectable ifn throughout the infection. relatively resistant b10.br mice that exhibit variant-specific immunity and control the first peak of parasitemia exhibited detectable ifn at two intervals. the appearance of ifn in b10.br serum first coincide ...	1985	2579155
growth and antigenic variation of trypanosoma brucei, t. rhodesiense and t. gambiense in subcutaneous millipore chambers.	the inability to cultivate infective bloodstream forms of the african trypanosomes in cell-free media has complicated studies of the biology of trypanosomes and the pathogenesis of trypanosomiasis. we attempted to overcome this problem by subcutaneous implantation in mice of millipore chambers that isolate trypanosomes from cells but permit diffusion of soluble substances across their membranes. chambers were inoculated with 5 x 10(4) to 5 x 10(5) per ml trypanosoma brucei, t. rhodesiense or t. ...	1985	2581337
calcium-dependent endoribonuclease of trypanosoma brucei has a base-preferential affinity to adenylate.	the substrate specificity of a calcium-dependent endoribonuclease of trypanosoma brucei cytoplasm has been further determined. the actions of the enzyme on transfer rna, ribosomal rna and various synthetic polyribonucleotides indicate that the enzyme degrades double-stranded as well as single-stranded rnas; while it preferentially hydrolyses polyribonucleotides having adenylic acid residues, and has a pronounced preference for poly (adenylic acid). its apparent michaelis constant (km) values usi ...	1985	2581576
homologies between paraflagellar rod proteins from trypanosomes and euglenoids revealed by a monoclonal antibody.	a nonidet p 40 insoluble fraction was isolated from trypanosoma brucei and was used to raise a monoclonal antibody (5e9). the antigen was localized by indirect immunofluorescence in the flagellum of t. brucei and of two species of euglenoids, euglena gracilis and distigma proteus. in immunoblot analysis, 5e9 appeared to bind to paraflagellar rod proteins pfr1 and pfr2 of t. brucei (72000 and 75000 mol. wt.) and of e. gracilis (67000 and 76000 mol. wt.). the presence of a common epitope in parafl ...	1985	2581783
adp-ribosyl transferase activity in trypanosoma brucei.	nuclear adenosine diphosphoribosyl transferase (adprt) catalyses the covalent modification of chromatin proteins by (adp-ribose)n. this activity, which is entirely dependent on dna containing strand breaks, is required for efficient dna excision repair possibly because it regulates dna ligation. adprt activity is also required for cytodifferentiation in a number of different cell types. we report here the presence of adprt activity in the blood-stream form of trypanosoma brucei and its activatio ...	1985	2985984
further analysis of intraspecific variation in trypanosoma brucei using restriction site polymorphisms in the maxi-circle of kinetoplast dna.	we have compared the maxi-circle kinetoplast dna of 21 trypanosoma brucei sp. stocks by analysis of restriction sites for nine restriction endonucleases. the analysis shows most of these stocks to have a maxi-circle sequence similar to that of 11 previously analysed stocks, with a difference of less than 3% between any two stocks. however, seven stocks stand out from the rest with at least two sites lost or gained for six of the nine restriction enzymes used. these seven distinctive stocks fall ...	1985	2985985
(taa)n within sequences flanking several intrachromosomal variant surface glycoprotein genes in trypanosoma brucei.	in trypanosoma brucei telomeric copies of intrachromosomal variant surface glycoprotein (vsg) genes are produced through a gene conversion mechanism and are expressed if the telomere is or becomes transcriptionally activated. we have analyzed a sequence that occurs 1 to 1.5 kb 5' to several intrachromosomal vsg genes. this flanking sequence has three distinct sections: a 5' section containing 5 to 116 taa or taa-like tandem repeats; a moderately conserved sequence with an alternating gt characte ...	1985	2987874
two simultaneously active vsg gene transcription units in a single trypanosoma brucei variant.	trypanosomes can change their surface coat either by slotting a different surface antigen gene copy into an active (telomeric) expression site or by activating a new vsg gene expression site and inactivating the old one. how expression sites are activated or inactivated is not clear. we report an exceptional trypanosome variant in which the inactivation of a surface antigen gene is accompanied by a 30 kb dna insertion 5' of the gene. transcription of the region upstream of the insertion continue ...	1985	2988791
identification of mitochondrial genes in trypanosoma brucei and homology to cytochrome c oxidase ii in two different reading frames.	we have determined the nucleotide sequence of a 3.3 kilobase segment of the kdna maxicircle of trypanosoma brucei brucei 164. the nucleotide sequence and its predicted translated sequence have homology to cytochrome c oxidase subunits i and ii (co i and ii) and mammalian unidentified reading frame 1 (urf 1). amino acid homology to co ii extends for 170 residues from the amino terminus in one reading frame and then continues in another reading frame for 39 residues to the carboxyl terminus. simil ...	1985	2989684
inactivation and reactivation of a variant-specific antigen gene in cyclically transmitted trypanosoma brucei.	in trypanosoma brucei, the activation of the variant-specific antigen gene antat 1.1 proceeds by the synthesis of an additional gene copy, the antat 1.1 elc, which is transposed to a new location, the expression site, where it is transcribed. using the antat 1.1 variant to infect flies, we investigated the fate of the antat 1.1 elc during cyclic transmission of t. brucei. we show here that the antat 1.1 elc is conserved in procyclic trypanosomes, obtained either from the midgut of infected gloss ...	1985	2990917
synthesis of a hydrolase for the membrane-form variant surface glycoprotein is repressed during transformation of trypanosoma brucei.	a membrane-bound phospholipase c-like hydrolase present in lysates of bloodstream forms of trypanosoma brucei rapidly converts the membrane form of the variant surface protein to the soluble form and 1,2-dimyristoylglycerol [(1985) m.a.j. ferguson et al. j. biol. chem., 260, 4963-4968]. the hydrolase is inhibited by p-chloromercuribenzenesulfonate. the synthesis of the enzyme is rapidly repressed upon differentiation of bloodstream forms to procyclic cells and the enzyme activity declines to an ...	1985	2991000
helical packing in the hydrophobic sector of cytochrome c oxidase.	an arrangement for the membrane-spanning segments of the three larger subunits of cytochrome c oxidase is proposed on the basis of sequence comparison and polarity distribution estimated from the data available for 11 different organisms.	1985	2991455
biochemical peculiarities of trypanosomes, african and south american.		1985	2992672
effect of theophylline on differentiation of trypanosoma brucei.	differentiation of trypanosoma brucei in the mammal limits the degree of parasitemia and prepares the trypanosome for passage back into the tsetse fly. in an attempt to define the signals that control differentiation, we found that theophylline, in contrast to indomethacin, blocked differentiation, prolonged parasitemia, elevated prostaglandin and cyclic amp concentrations of rat plasma, and depressed intratrypanosomal cyclic amp. relatively nontoxic drugs that alter differentiation are powerful ...	1985	2993168
the two mechanisms for antigenic variation in trypanosoma brucei are independent processes.	antigenic switching in trypanosoma brucei can occur either by the production of a telomeric copy of a variant surface glycoprotein (vsg) gene through a gene conversion mechanism or by the nonduplicative activation of a telomeric vsg gene. the 5 vsg gene telomeric copy that is expressed in istar 1 variant antigenic type (vat) 5 is retained in an inactive state following an antigenic switch to vat a5. this inactive telomeric 5 vsg gene copy is absent following independent single antigenic switches ...	1985	2993880
a 5' spliced leader is added in trans to both alpha- and beta-tubulin transcripts in trypanosoma brucei.	the approximately 15 alpha- and 15 beta-tubulin genes of trypanosoma brucei are arranged in a tandem array of alternating alpha- and beta-tubulin genes. we have examined the structure of mrna transcripts from the tubulin gene family and have found at the 5' ends of both alpha- and beta-tubulin messages a 35-nucleotide spliced leader (sl) identical to that identified previously on the 5' ends of variant surface glycoprotein (vsg) mrnas. no 35-nucleotide sl sequences were encoded in the tubulin in ...	1985	2994042
effect of 3-aminobenzamide on antigenic variation of trypanosoma brucei.	african trypanosomes, like trypanosoma brucei, depend on antigenic variation to evade the immune response of the vertebrate host. an antigenic switch corresponds to the activation of a variable surface glycoprotein (vsg) gene from a large silent repertoire. most switches require the duplicative transposition of a vsg gene, which involves strand breaks in dna and subsequent repair. the nuclear enzyme adenosine-diphosphoribosyl transferase (adprt), which is dependent on the presence of dna strand ...	1985	2998400
structure and regulated expression of genes encoding fructose biphosphate aldolase in trypanosoma brucei.	low stringency hybridisation with a rabbit aldolase cdna was used to select cdna clones encoding fructose biphosphate aldolase in trypanosoma brucei. a clone which is almost full length encodes a protein of 41 027 daltons which has 50% identity with rabbit aldolase a and slightly lower homology with b-type aldolases. the homologous mrna is at least 6-fold more abundant in bloodstream trypomastigotes than in procyclic forms, as expected from measurements of enzyme activity. genomic mapping result ...	1985	2998772
the role of compartmentation and glycerol kinase in the synthesis of atp within the glycosome of trypanosoma brucei.	glycosomes, purified from trypomastigote forms of trypanosoma brucei, contained all the enzymes necessary to convert glucose to alpha-glycerophosphate and 3-phosphoglycerate. the multienzyme reaction which produces 2 alpha-glycerophosphate, 2 adp, and 2 nad+ from 1 glucose, 2 atp, and 2 nadh was studied spectrophotometrically. intact glycosomes, suspended with 5.6 mm alpha-glycerophosphate and 2 mm adp, produced atp inside the glycosomes for glucose phosphorylation at a rate of 0.7 mumol/min/mg ...	1985	2999127
putative regulatory sequences for the transcription of mini-exons in trypanosoma brucei as revealed by s1 sensitivity.	the 35-nucleotide (nt) mini-exon found at the 5' end of most trypanosoma brucei mrnas is encoded as part of a tandem 1.35-kb repeat in genomic dna. we cloned this dna and identified an s1-sensitive site in supercoiled plasmids containing mini-exon repeats. this site is situated on a poly(da-dt) stretch that is variable in length in different copies of repeat. poly(da-dt) is capable of forming abnormal dna helix configurations, some of which are induced by supercoiling. the s1 site may have a rol ...	1985	3000878
cytofluorometry as a method for the differentiation of trypanosomes.	the dna binding guanine specific antibiotic, chromomycin a3, has been evaluated for fluorescence intensity measurements of t. cruzi, t. brucei brucei and t. musculi. optimal fixation and staining conditions have been determined. the fluorometry was performed with a microscope photometer equipped with electronic systems for short time excitation of 7 milliseconds and operation control. the trypomastigote bloodstream forms of these species have a different chromomycin specific dna content. the tot ...	1985	3001914
purification and regulatory properties of phosphofructokinase from trypanosoma (trypanozoon) brucei brucei.	phosphofructokinase (ec 2.7.1.11) from trypanosoma (trypanozoon) brucei brucei was purified to homogeneity by using a three-step procedure that may be performed within 1 day. proteolysis, which removes a fragment of mr approx. 2000, may occur during the purification, but this can be prevented by including antipain, an inhibitor of cysteine proteinases, in the buffers during the purification. the subunits of the enzyme appear to be identical in size, with an mr of 49 000. the mr of the native enz ...	1985	3158309
a high affinity ca2+-dependent atpase in the surface membrane of the bloodstream stage of trypanosoma rhodesiense.	addition of ca2+ (0.01-1 mm) to a standard trypanosoma rhodesiense mg2+-atpase assay failed to elicit any increase in activity. however, in the absence of externally added mg2+ and using calcium-egta or calcium-cdta to precisely maintain free metal ion concentration, it was possible to measure a specific ca2+-atpase. cell fractionation studies revealed this atpase to be predominantly associated with subcellular particles having an equilibrium density of 1.22 g cm-3 and identified as surface memb ...	1985	3159962
the behaviour of trypanosomes within the midguts of wild-caught tsetse from zimbabwe.	trypanosomes infecting the midgut of wild-caught tsetse from zimbabwe were found on electron microscopic examination to be penetrating the peritrophic membranes and so entering the ecto-peritrophic space in the mycetome region of the midgut. other trypanosomes entered midgut cells, behaviour similar to that previously reported in laboratory-infected tsetse colonies.	1985	3832497
the behaviour of trypanosomes in liberian tsetse.		1985	3832504
an assay for screening drugs against animal-infective bloodstream forms of trypanosoma brucei brucei in vitro.	a rapid and simple assay for in vitro drug screening has been established using the mammalian feeder layer cell system for continuous cultivation of infective bloodstream forms of trypanosoma brucei brucei. a total of 21 trypanocides have been tested. differences in sensitivity to standard trypanocides were detected among drug-susceptible isolates and strains of t. b. brucei. this assay may thus be of potential use for rapid detection of new drug-resistant isolates of t. b. brucei.	1985	3836123
further studies on acquisition of potential infectivity for man in closely related trypanosoma trypanozoon brucei clones.	twelve clones were isolated from relapsing populations in an infection initiated with a clone-derived human serum resistant trypanozoon. isolates were serotyped by the immunotrypanolysis test and four distinct variable antigen types (vats) designated witat 4, 5, 6 and 7 were identified. contemporaneous blood incubation infectivity testing (biit) showed that most clones isolated in the course of infection were resistant to normal human serum while some clones isolated after series of relapses wer ...	1985	3836215
the spliced leader sequence of trypanosoma brucei has a potential role as a cap donor structure.	trypanosoma brucei brucei and other trypanosomatid species are unique among eucaryotes because transcription of their protein-coding genes is discontinuous. the 5' ends of their mrnas consist of an identical 35-nucleotide spliced leader which is encoded at a separate locus from that for the body of the protein-coding transcript. we show here that the spliced leader transcript contains a 5' cap structure and suggest that at least one function of the spliced leader sequence is to provide a cap str ...	1985	3837191
conservation of structure detected in two trypanosome surface glycoproteins by amino acid sequence alignment.	the predominant molecule exposed to antibody on the surface of trypanosoma brucei is a glycoprotein of about 60 000 molecular weight which varies in amino acid sequence. the complete sequences of two such variable surface glycoproteins (vsgs) from randomly isolated, different antigenic types of trypanosomes were compared by amino acid sequence alignment. homologous sequences were found distributed over various regions of the vsgs. particularly good homology was observed between residues 16-34, 9 ...	1985	3838798
trypanosoma brucei: a surface antigen mrna is discontinuously transcribed from two distinct chromosomes.	the mrnas for variant surface glycoproteins (vsgs) and many other proteins in trypanosoma brucei start with the same sequence of 35 nucleotides, encoded by a separate mini-exon. there are approximately 200 mini-exon genes per trypanosome and these are highly clustered on large chromosomes. we have found two trypanosome variants that express a vsg gene located on a small, 225-kb chromosome. each gene yields a mrna containing the 35-nucleotide sequence even though the 225-kb chromosome does not co ...	1985	3839457
stimulation of trypanosoma brucei pyruvate kinase by fructose 2,6-bisphosphate.	the activity of pyruvate kinase present in a crude extract of the bloodstream form of trypanosoma brucei was greatly increased by fructose 2,6-bisphosphate, which converted the saturation curve for phosphoenolpyruvate from a sigmoid into a hyperbola with no change in v. phosphate and arsenate had an effect opposite to that of fructose 2,6-bisphosphate and the apparent ka for fructose 2,6-bisphosphate was shifted from 75 nm to 1.5 microm by the presence of 5 mm phosphate. fructose 1,6-bisphosphat ...	1985	3841061
enzyme variation in t. brucei ssp. ii. evidence for t. b. rhodesiense being a set of variants of t. b. brucei.	a collection of stocks of trypanosoma brucei rhodesiense isolated in kenya have been examined for electrophoretic variation in 20 enzymes. the results obtained have been analysed in order to determine whether these trypanosomes are diploid and undergo mating and to determine the genetic distance between t. b. rhodesiense, t. b. brucei and t. b. gambiense. the enzyme electrophoretic markers were further used in experiments involving cyclically transmitted mixtures of stocks aimed at detecting gen ...	1985	3856830
rapid processing of the carboxyl terminus of a trypanosome variant surface glycoprotein.	the variant surface glycoprotein of the parasite trypanosoma brucei contains a glycolipid of unknown structure covalently attached to its cooh terminus. we have shown, by using metabolic labeling with [35s]methionine or [3h]myristic acid, precipitation with specific antibodies, and nadodso4/polyacrylamide gel electrophoresis, that this glycolipid is attached to the variant surface glycoprotein polypeptide within 1 min after its translation.	1985	3858818
differential expression of mitochondrial genes between life cycle stages of trypanosoma brucei.	the mitochondrial respiratory system is differentially produced during the life cycle of the parasitic protozoan, trypanosoma brucei. we have found 14 transcripts that are derived from a maxicircle (mitochondrial dna) region that contains sequences homologous to cytochrome c oxidase subunits i and ii, unassigned reading frame 1 from mitochondrial dna of other organisms, and two other open reading frames. ten of these transcripts occur as pairs that differ in size by approximately equal to 200 nu ...	1985	3858825
calmodulin genes in trypanosomes are tandemly repeated and produce multiple mrnas with a common 5' leader sequence.	in trypanosoma brucei gambiense, the ca2+ binding protein calmodulin is encoded by three identical tandemly repeated genes. the transcripts of these genes consist of several rna species similar in size. a 35-nucleotide spliced leader sequence is present at the 5' end of each mrna but is not encoded by dna contiguous to these genes. we have identified two different sites for the fusion of the leader to the mrna. these results strongly support the idea that a novel, possibly discontinuous, transcr ...	1985	3858856
molecular genetics of antigenic variation in trypanosomes.		1985	3870638
high and low responsiveness of bovine lymphocytes to trypanosoma brucei in vitro: lack of correlation with resistance to trypanosomiasis.	bovine peripheral blood lymphocytes (pbl) were stimulated to proliferate in vitro by live, irradiated or freeze-thawed trypanosoma brucei, but not by the isolated variant surface glycoprotein. the optimal dose was 10(5) trypanosomes per 5 x 10(5) lymphocytes in 0.2 ml. maximal proliferation was at day 5. of the 98 cattle tested, 36 were high-responders (stimulation indexes 20-104), 49 were low or non-responders (si 1-10) and 13 were intermediate. the responder status of individual animals did no ...	1985	3871728
suppressor factor of t-cell activation and decreased interleukin 2 activity in experimental african trypanosomiasis.	spleen cells from trypanosoma brucei-infected balb/c mice were unable to respond to a t-cell mitogen, concanavalin a. moreover, they were unable to produce detectable amounts of the growth factor required for t cell proliferation, interleukin 2. in addition, supernatants from 24-h in vitro cultures of these cells produced a slight but detectable suppressive activity of the interleukin 2-dependent proliferation of a t-cell line. infected spleen cells also suppressed the response of t. brucei-immu ...	1985	3876993
structure and transcription of a telomeric surface antigen gene of trypanosoma brucei.	the gene encoding variant surface glycoprotein 221 in trypanosoma brucei is located adjacent to a chromosome end and can be activated with or without a concomitant gene duplication. to test whether transcription initiates within the cloned segment of the 221 gene, we analyzed nascent and stable transcripts. we show here that the 221 coding region and 8.5 kilobases of adjacent upstream dna are transcribed into nascent rna at a similar rate when gene 221 is activated without duplication. since onl ...	1985	3879972
trypanothione: a novel bis(glutathionyl)spermidine cofactor for glutathione reductase in trypanosomatids.	glutathione reductase from trypanosomes and leishmanias, unlike glutathione reductase from other organisms, requires an unusual low molecular weight cofactor for activity. the cofactor was purified from the insect trypanosomatid crithidia fasciculata and identified as a novel glutathione-spermidine conjugate, n1,n8-bis(l-gamma-glutamyl-l-hemicystinyl-glycyl)spermidine, for which the trivial name trypanothione is proposed. this discovery may open a new chemotherapeutic approach to trypanosomiasis ...	1985	3883489
comparative study of the ribosomal rna from leishmania and trypanosoma.	the ribosomal rna from several stocks of the genera leishmania and trypanosoma were studied by gel electrophoresis, sedimentation on sucrose density gradients and rna/dna hybridization experiments. three major components were observed after electrophoresis in polyacrylamide gels (page-sds), the relative molecular masses being respectively: x1 = 0.83 megadaltons, x2 = 0.63 megadaltons and x3 = 0.54 megadaltons for leishmania rna; and x1 = 0.86 megaldaltons, x2 = 0.78 megadaltons, and x3 = 0.58 me ...	1985	3886897
trypanosoma brucei: analysis of relapsing populations in sensitive and resistant breeds of cattle.	the clone ditat 1.1 of trypanosoma brucei brucei was injected into four bovids, and clones obtained from successive waves of parasitemia were used to study the expressed variant-specific surface glycoprotein repertoire. twenty-four clones were obtained which could be classified into 12 different variable antigen types, in addition to the clone injected, using agglutination or immunofluorescence with monospecific antisera. the variable surface glycoproteins of the 25 clones were extracted using t ...	1985	3894044
cultivation of african and south american trypanosomes of medical or veterinary importance.		1985	3896374
biosynthesis, attachment and release of variant surface glycoproteins of the african trypanosome.		1985	3896675
glycosylation of the variant surface antigens of trypanosoma brucei.		1985	3896676
regulation of parasitaemia in mice infected with trypanosoma brucei.		1985	3896678
sulphydryl-dependent enzymes from african trypanosomes.		1985	3898094
molecular identity and location of invariant antigens on trypanosoma brucei rhodesiense defined with monoclonal antibodies reactive with sera from trypanosomiasis patients.	monoclonal antibodies (mabs) which are reactive with several antigenically distinct variable antigen types were prepared by immunization with trypanosoma brucei rhodesiense. certain mabs were shown to be specific for members of the genus trypanosoma and not reactive with leishmania spp. or plasmodium falciparum by the indirect immunofluorescence assay. these genus-specific mabs were used to identify the molecular location of these invariant antigen determinants in whole t. brucei rhodesiense ant ...	1985	3905617
adenosine cycle in african trypanosomes.	african trypanosomes can convert adenosine to adenosine monophosphate. however, in trypanosoma brucei, as in t. vivax and t. congolense, most of the adenosine is broken down to adenine before conversion to the nucleotide by adenine phosphoribosyltransferase. trypanosoma brucei and t. vivax use the purine nucleoside hydrolase for adenosine cleavage while t. congolense uses purine nucleoside phosphorylase for the nucleoside cleavage. trypanosoma vivax also deaminates adenine to hypoxanthine before ...	1985	3920982
catalytic irreversible inhibition of trypanosoma brucei brucei ornithine decarboxylase by substrate and product analogs and their effects on murine trypanosomiasis.	ornithine decarboxylase from trypanosoma brucei brucei was inhibited by several substrate (ornithine) and product (putrescine) analogs both in vitro and in vivo. since alpha-difluoromethylornithine is effective for the treatment of experimental and clinical african trypanosomiasis, it was possible that the more potent ornithine and putrescine analogs might be more active in treating the disease. however, only alpha-monofluoromethyldehydroornithine methyl ester was more potent than alpha-diflurom ...	1985	3924048
developmental cycles and biology of pathogenic trypanosomes.		1985	3928017
application of new technologies to epidemiology.		1985	3928018
conservation of a 29-base-pair sequence within maxicircle ars fragments from six species of trypanosomes.	the maxicircles from trypanosoma brucei, herpetomonas samuelpessoai, leptomonas seymouri, and phytomonas davidi were examined for the presence of a 29-bp sequence termed cf29 that has been found in the ars 189 sequence from the crithidia fasciculata maxicircle and in lt-ars 189 from the maxicircle of leishmania tarentolae. the cf29 sequence also contains a yeast consensus ars of (t/a)tttatputtt(t/a). all of the maxicircles examined contained specific fragments that hybridized to the cf29 probe. ...	1985	3938423
the aerobic/anaerobic transition of glucose metabolism in trypanosoma brucei.	the ratio of glycerol to pyruvate produced by t. brucei incubated with glucose at various oxygen tensions has been used as an index of the aerobic and anaerobic pathways of glucose metabolism. a minimal model is presented which fits the observed data. the value of the notional k of the aerobic/anaerobic transition from the model is close to that of the km of trypanosomal glycerophosphate oxidase. the anaerobic pathway appears to be almost completely inoperative at oxygen tensions in the range of ...	1985	3972106
neutralization of individual variable antigen types in metacyclic populations of trypanosoma brucei does not prevent their subsequent expression in mice.	the trypanosoma brucei metacyclic population in the salivary glands of the tsetse fly displays a characteristic set of variable antigen types (vats) which represents only a restricted part of the parasite's total vat repertoire. after introduction into the mammalian host by fly bite, the metacyclics transform into bloodstream forms which retain expression of the metacyclic vats. specific antibodies, both polyvalent and monoclonal, have been used to neutralize separately 4 individual vats from me ...	1985	3982856
inosine analogs as chemotherapeutic agents for african trypanosomes: metabolism in trypanosomes and efficacy in tissue culture.	certain purine analogs, the pyrazolopyrimidines, are effective chemotherapeutic agents against leishmania spp. and trypanosoma cruzi both in vitro and in some clinical models. heretofore they have not been effective against the african trypanosomes; this suggested that these organisms were not comparable to the other pathogens with respect to their purine metabolism. we have studied the efficacy and metabolism of the pyrazolopyrimidine bases allopurinol and thiopurinol, their respective ribonucl ...	1985	3985595
trypanosoma brucei variant surface glycoprotein has a sn-1,2-dimyristyl glycerol membrane anchor at its cooh terminus.	the membrane form of trypanosoma brucei variant surface glycoprotein (mfvsg) is acylated with ester-linked tetradecanoic (myristic) acid (ferguson, m. a. j., and cross, g. a. m. (1984) j. biol. chem. 259, 3011-3015). comparative analysis of pronase peptides from mfvsg and soluble vsg localizes the site of mfvsg acylation to a cooh-terminal oligosaccharide structure. chemical and enzymatic treatment of the acylated pronase mfvsg fragment revealed that the myristic acid is present as a diglyceride ...	1985	3988741
release of the variable surface coat glycoprotein from trypanosoma brucei requires the cleavage of a phosphate ester.	the membrane-bound and released forms of the variant surface coat glycoprotein from trypanosoma brucei have been purified to homogeneity by a new rapid method in the absence of detergents. the conversion of the membrane-bound form to the released form has been found to consist of the cleavage of a phosphodiester bond, distal to the phosphate, linking the protein to a phospholipid. we suggest that this linkage constitutes the normal mode of attachment of the protein to the outer leaflet of the pl ...	1985	3988749
simultaneous isolation of cytoplasmic endoribonuclease and exoribonuclease of trypanosoma brucei.	an endoribonuclease and an exoribonuclease have been isolated simultaneously from the cytoplasm of trypanosoma brucei by hydroxyapatite column chromatography. the endoribonuclease produced oligonucleotides from poly(adenylic acid) with 5'-phosphate and 3'-oh termini. the exoribonuclease produced only ribonucleoside 5'-phosphates from poly(adenylic acid). the relative rates of degradation of synthetic homopolynucleotides by the endoribonuclease under standard conditions were in the order poly(ade ...	1985	3990709
induction of human serum-sensitive trypanosoma brucei stabilates into human serum-resistant "t. rhodesiense".	when chronic trypanosoma brucei infections of mice are treated with 20 mg/kg suramin, those trypanosomes which have escaped chemotherapy because they are residing in the brain, exhibit a higher degree of human serum resistance than the original infection. this resistance increases if the chronic infection is retreated for a second time, before the trypanosomes in the brain are tested by the blood incubation infectivity test. the transformation is not due to a selection of t. rhodesiense from a t ...	1985	3992646
structure and variation within variant surface glycoproteins of trypanosoma brucei.	variant surface glycoproteins of the african trypanosomes are members of a multigene family which show extraordinary amino sequence diversity. the extent of this diversity and the significance of homologies both in the amino acid sequence and in the post-translational modifications are discussed in the light of what is predicted for the structure of these molecules and what is now known from x-ray crystallographic analysis.	1985	3994303
cross-linking of the enzymes in the glycosome of trypanosoma brucei.	glycosomes, the microbody-like organelles containing mainly glycolytic enzymes, were purified from the long slender bloodstream form of trypanosoma brucei eatro 110 monomorphic strain by an improved method in which the protozoa were frozen and thawed in 15% glycerol to free, from the plasma membrane, much of the variant surface glycoprotein which used to constitute the major contaminant of our purified glycosomes. the purified glycosomes have 11 major proteins, 6 of which, tentatively identified ...	1985	3997856
interactions between trypanosoma brucei and babesia spp. and plasmodium spp. in mice.	swiss mice with chronic trypanosoma brucei infections become refractory to subsequent infection with babesia microti and b. rodhaini. infection with b. microti 7 days after t. brucei resulted in an obvious inhibition of the babesia parasitaemias and this inhibition became more profound as the time interval between the infections increased, until at 17-20 days the parasitaemias were totally abolished. even after intravenous injection of large numbers of parasites parasitaemias were inhibited. sim ...	1985	4000702
cultivation in a semi-defined medium of animal infective forms of trypanosoma brucei, t. equiperdum, t. evansi, t. rhodesiense and t. gambiense.	a semi-defined medium for the cultivation of bloodstream forms of the african trypanosome brucei subgroup was developed. out of 14 different strains tested, 10 could be cultured including trypanosoma brucei, t. equiperdum, t. evansi, t. rhodesiense and t. gambiense. the presence of a reducing agent (2-mercaptoethanol or thioglycerol) was found to be essential for growth. the standard medium consisted of hepes buffered minimum essential medium with earle's salts supplemented with 0.2 mm 2-mercapt ...	1985	4006919
the solubilization of a sham sensitive, cyanide insensitive ubiquinol oxidase from trypanosoma brucei.		1985	4009352
trypanosome variant surface glycoprotein genes expressed early in infection.	we have studied further the genes for trypanosomal variant surface glycoproteins expressed during a chronic infection of rabbits with trypanosoma brucei, strain 427. we show that there are three closely related chromosomal-internal isogenes for vsg 121; expression of one of these genes is accompanied by the duplicate transposition of the gene to a telomeric expression site, also used by other chromosome-internal vsg genes. the 3' end of the 121 gene is replaced during transposition with another ...	1985	4009712
maternally derived immunity in young mice to infection with trypanosoma brucei and its potentiation by berenil chemotherapy.	young mice which were allowed to suckle, from birth, a mother infected with trypanosoma brucei, or a mother whose infection had been cured before parturition with berenil chemotherapy, were themselves immune to homologous trypanosome challenge. this immunity extended until approximately 25 days of age, and was transmitted in the colostrum/milk of the mother. mice born of infected mothers, but transferred at birth to normal foster mothers, were susceptible to trypanosome infection. drug prophylax ...	1985	4011302
the 5.8s ribosomal rna gene of trypanosoma brucei: structural and transcriptional studies.	to further investigate the process of discontinuous transcription in trypanosomes, the 5.8s rrna gene, present in the trypanosome genome as part of the multicopy rrna gene cluster, has been cloned, sequenced, chromosomally mapped, and used in transcriptional studies. the gene's sequence confirms its identity and indicates that it is less conserved evolutionarily than the trypanosome 5s rrna gene previously described by our laboratory (6). examination of the chromosomal locations of the gene by p ...	1985	4011434
heat shock genes: regulatory role for differentiation in parasitic protozoa.	the parasitic protozoa trypanosoma brucei and leishmania major are transmitted by insect vectors to their mammalian hosts. the temperature difference between the hosts (25 degrees and 37 degrees c) may induce a heat shock response in the parasite. transcripts of heat shock genes (homologous to hsp70 and hsp83) were 25 to 100 times more abundant in trypanosoma brucei bloodstream forms (trypomastigotes) than in insect (procyclic) stages. in leishmania major the patterns of heat shock gene expressi ...	1985	4012301
trypanosomal cardiac valvulitis in vervet monkeys.	quarantined vervet monkeys (cercopithecus aethiops) were infected with trypanosoma brucei (10(4) parasites/animal) in a tsetse free area. thirteen monkeys (11 infected with t.b. rhodesiense and 2 with t.b. brucei) were studied. animals became parasitaemic within one week after infection. the infection time lasted between 21 and 129 days; in 8 monkeys it was between 50 and 70 days. macroscopically massive pericarditis was observed in one, pericardial effusion in one, small apical aneurysms in thr ...	1985	4023556
trypanosoma brucei: infectivity and immunogenicity of cultured parasites.	trypanosoma brucei brucei, derived from the salivary glands of infected tsetse flies (glossina morsitans morsitans) and maintained in culture for over 4 years, were infective to both albino rats and tsetse flies. virulence was markedly enhanced during the first passage in albino rats or tsetse flies. irradiated cultured trypanosomes induced immunity to homologous challenge but not to tsetse fly or blood-induced challenge with the same stock.	1985	4029345
characterization of the trypanosoma brucei 5s ribosomal rna gene and transcript: the 5s rrna is a spliced-leader-independent species.	recent studies have shown that transcription occurs discontinuously for many genes in trypanosoma brucei. to further investigate details of transcription in trypanosomes, the genes for the 5s ribosomal rna from trypanosoma brucei rhodesiense and trypanosoma brucei brucei were cloned. sequence analysis and southern blotting showed the genes to be arranged in highly conserved tandem repeats of approx. 740 bp, which have no relation to the conserved 35-base spliced-leader repeat element. the genes ...	1985	4029619
differentiation in trypanosoma brucei: host-parasite cell junctions and their persistence during acquisition of the variable antigen coat.	acquisition of the variable antigen-containing surface coat of trypanosoma brucei occurs at the metacyclic stage in the salivary glands of the tsetse fly vector. the differentiation of the metacyclic trypanosome in the gland has been studied by scanning electron microscopy and by transmission electron microscopy of thin sections and freeze-fracture replicas. the uncoated epimastigote trypanosomes (with a prenuclear kinetoplast) divide while attached to the salivary gland epithelium brush border ...	1985	4030903
transport of ethanolamine and its incorporation into the variant surface glycoprotein of bloodstream forms of trypanosoma brucei.	the membrane-attached form of the variant surface glycoprotein (mf-vsg) of bloodstream forms of trypanosoma brucei is anchored to the plasma membrane by a hydrophobic c-terminal lipo-oligosaccharide containing ethanolamine. analysis by polyacrylamide gel electrophoresis showed that several different cloned t. brucei strains (strain eatro 110 and variants 117 and 118 of strain 427) incorporated [3h]ethanolamine into both mf-vsg and the soluble vsg derived from it, but not into other proteins. oth ...	1985	4033688
suppression of trypanosoma congolense, t. vivax and t. brucei infection rates in tsetse flies maintained on goats immunized with uncoated forms of trypanosomes grown in vitro.	significant suppression in the incidence of cyclical development of trypanosoma congolense, t. vivax and t. brucei occurred in glossina morsitans centralis maintained on goats immunized with in vitro-propagated uncoated forms of t. congolense, t. vivax and t. brucei, respectively. this was observed when tsetse given a t. congolense-infected feed were subsequently maintained on uninfected immunized goats and also when uninfected tsetse were fed on immunized goats infected with t. congolense, t. v ...	1985	4034247
colostral transfer of antibodies to trypanosoma brucei in goats.		1985	4037899
inhibition of trypanosoma brucei brucei peptidyl transferase activity by sparsomycin analogs and effects on trypanosome protein synthesis and proliferation.	peptidyl transferase activity of trypanosoma brucei brucei polyribosomes was competitively inhibited by analogs of sparsomycin (ki = 1-100 microm). the analogs were also potent inhibitors of [3h]-leucine and [3h]mannose incorporation into the proteins of intact trypanosomes with little or no effect on overall respiratory rate, suggesting a specific site of action for these analogs on protein synthesis. the peptidyl transferase inhibitors were effective at low concentrations at limiting the proli ...	1985	4038323
tubulin genes of the african trypanosome trypanosoma brucei rhodesiense:nucleotide sequence of a 3.7-kb fragment containing genes for alpha and beta tubulins.	most tubulin genes of the african trypanosome trypanosoma rhodesiense are contained in 3.7-kb tandemly repeating units. one member of the 3.7-kb repeat family has been isolated from a t. rhodesiense genomic library, cloned, and sequenced. the 3646-bp fragment contains a complete alpha-tubulin gene and portions of two beta-tubulin genes. no introns are present. the genes are separated by 634- and 333-bp intergenic regions, which lack typical eukaryotic promoter and poly(a) signal sequences. howev ...	1985	4043732
cysteine eliminates the feeder cell requirement for cultivation of trypanosoma brucei bloodstream forms in vitro.	in all previous studies, bloodstream forms of trypanosoma brucei could be grown in vitro only when supported by a feeder layer of mammalian fibroblasts. we have axenically cultivated bloodstream t. brucei by adding l-cysteine at regular intervals and appropriate concentrations. the optimum cysteine concentration depends on cell density and is close to physiological serum levels. at concentrations greater than 24 mg/liter (2 x 10(-4) m), cysteine was acutely toxic to trypanosome concentrations of ...	1985	4045385
a new method for the rapid purification of both the membrane-bound and released forms of the variant surface glycoprotein from trypanosoma brucei.	a simple new technique was developed for the rapid purification of either the membrane-bound or the released forms of the variant surface glycoprotein of trypanosoma brucei in high yield. whole cells were used as the source of the membrane-bound form, and the supernatant of benzyl alcohol-treated cells was used as the source of the released form. the technique was based on extraction of the acid-treated protein into chloroform/methanol, followed by selective re-partition into aqueous salt soluti ...	1985	4052037
trypanosoma brucei: the extent of conversion in antigen genes may be related to the dna coding specificity.	the boundaries of gene conversion in variant-specific antigen genes have been determined in six clones of trypanosoma brucei. in each clone, antigenic switching involved interaction between two telomeric members of the antat 1.1 multigene family, which share extensive homology throughout their coding regions. all conversion events occurred by substitution of faithful copies of donor sequences. conversion endpoints were nonrandomly distributed. in four clones, the 5' conversion limit was near the ...	1985	4053185
glycosyl-sn-1,2-dimyristylphosphatidylinositol is covalently linked to trypanosoma brucei variant surface glycoprotein.	the cooh terminus of the externally disposed variant surface glycoprotein (vsg) of the eukaryotic pathogenic protozoan trypanosoma brucei strain 427 variant mitat 1.4 (117) is covalently linked to a novel phosphatidylinositol-containing glycolipid. this conclusion is supported by analysis of the products of nitrous acid deamination or staphylococcus aureus phosphatidylinositol-specific phospholipase c treatment of purified membrane-form vsg. lysis of trypanosomes is accompanied by release of sol ...	1985	4055788
comparison of african trypanosomes of different antigenic phenotypes, subspecies and life cycle stages by two-dimensional gel electrophoresis.	high resolution two-dimensional polyacrylamide gel (2d gel) electrophoresis and autoradiography were used to analyze the protein gene products of african trypanosomes biosynthetically labelled with [35s]methionine. using cloned populations of parasites it was found that: antigenically different bloodstream trypanosomes from the same serodeme differed only in their variant surface glycoproteins; trypanosoma brucei, t.b. rhodesiense and t.b. gambiense subspecies could be distinguished on the basis ...	1985	4058485
trypanosoma brucei: differentiation of in vitro-grown bloodstream trypomastigotes into procyclic forms.	trypanosoma brucei strain 366d trypomastigotes grown at 37 degrees c in the presence of a human fibroblast cell line formed foci underneath the feeder cells whereas trypanosomes grown in the presence of a human epithelial cell line grew only in the culture supernatant. a culture system was developed to study the differentiation of bloodstream trypomastigotes grown in the epithelial cell system into procyclic trypomastigotes at 27 degrees c. the morphological differentiation into the procyclic fo ...	1985	4067881
protection of the sleeping sickness trypanosome from chemotherapy by different parts of the brain.		1985	4076024