| the maxicircle of trypanosoma brucei kinetoplast dna hybridizes with a mitochondrial gene encoding cytochrome oxidase subunit ii. | a restriction endonuclease fragment of the maxicircle of trypanosoma brucei brucei kinetoplast dna hybridizes with a cloned mitochondrial dna sequence which encodes cytochrome oxidase subunit ii of zea mays. a cloned mitochondrial dna sequence encoding cytochrome oxidase subunit ii of saccharomyces cerevisiae also hybridized with kdna, but exhibits less homology with the maxicircle than does the maize gene. the hybridizing maxicircle dna was localized to a 2.8 kbp segment which is bounded by taq ... | 1982 | 6287257 |
| rna splicing is required to make the messenger rna for a variant surface antigen in trypanosomes. | the expression of the gene for variant surface glycoprotein (vsg) 118 in trypanosoma brucei is activated by transposing a dna segment containing the gene and 1-2 kb in front of it to an expression site elsewhere in the genome. by s1 nuclease protection and rna blotting experiments we show here the presence of several minor transcripts in trypanosomes synthesizing vsg 118, one of which covers the entire transposed segment. comparison of the sequence of the 5' terminal segment of vsg 118 messenger ... | 1982 | 6287414 |
| an analysis of cosmid clones of nuclear dna from trypanosoma brucei shows that the genes for variant surface glycoproteins are clustered in the genome. | trypanosoma brucei contains more than a hundred genes coding for the different variant surface glycoproteins (vsgs). activation of some of these genes involves the duplication of the gene (the basic copy or bc) and transposition of the duplicate to an expression site (yielding the expression-linked copy or elc). we have cloned large fragments of genomic dna in cosmid vectors in escherichia coli. cosmids containing the bcs of genes 117, 118 and 121 were readily obtained, but dna containing the el ... | 1982 | 6292859 |
| subcellular distribution of adenylate cyclase, cyclic-amp phosphodiesterase, protein kinases and phosphoprotein phosphatase in trypanosoma brucei. | the subcellular distribution of adenylate cyclase, cyclic-amp phosphodiesterase, protein kinases and phosphoprotein phosphatase in bloodstream forms of trypanosoma brucei was determined by isopycnic sucrose-gradient centrifugation of post-large-granule extracts. cyclic-amp phosphodiesterase was almost entirely soluble whereas adenylate cyclase was membrane-bound. the latter enzyme appeared to be absent from the plasma-membrane fraction but copurified with acid phosphatase and acid phosphodiester ... | 1982 | 6294515 |
| the iltat 1.4 surface antigen gene family of trypanosoma brucei. | the cdna sequence for the variable surface glycoprotein (vsg) expressed in trypanosoma brucei clone iltat 1.4 (called clone d for brevity) hybridizes strongly to three regions in trypanosome genomic dna. these three regions were extensively characterized by southern hybridization analyses, genomic dna cloning and dna sequence determinations. all three regions occur in the genomes of all trypanosome clones of the iltar 1 repertoire regardless of whether or not vsg d was being expressed. extensive ... | 1982 | 6294609 |
| ribosomal rna genes of trypanosoma brucei. cloning of a rrna gene containing a mobile element. | an ordered restriction map of the ribosomal rna genes of trypanosoma brucei brucei is presented. bgl ii fragments of t.b.brucei genomic dna were cloned into pat 153, and the clones containing rdna identified. restriction maps were established and the sense strands identified. one clone was shown by heteroduplex mapping to contain a 1.1 kb inserted sequence which was demonstrated to be widely distributed throughout the genomes of members of the subgenus trypanozoon. however, in two other subgener ... | 1982 | 6294613 |
| purification and properties of dihydroorotate oxidase from crithidia fasciculata and trypanosoma brucei. | dihydroorotate oxidases have been highly purified from the parasitic protozoa crithidia fasciculata and trypanosoma brucei. the crithidia enzyme was purified 4200-fold from a crude soluble protein extract in four steps. the protein is a dimer as judged from the native (mr 60 000) and subunit (mr 32 700) molecular weights. the purified enzyme exhibits a characteristic flavin electronic spectrum, and each mole of native dimer contains 1.0 mol of tightly bound flavin mononucleotide. under anaerobic ... | 1983 | 6299333 |
| relationship between multiple copies of a t. brucei variable surface glycoprotein gene whose expression is not controlled by duplication. | unlike many other t. brucei variable surface glycoprotein (vsg) genes, the iitat 1.3 gene is not duplicated when it is expressed. analysis of the multiple copies of this gene present in all iitar 1 trypanosome clones by restriction enzyme mapping and sequencing shows that the expressed copy may have arisen by duplication and transposition to a telomeric site, as is observed for those vsg genes whose expression is linked to duplication. the existence of a mechanism selecting between a number of c ... | 1983 | 6301682 |
| macrophage activation in murine african trypanosomiasis. | african trypanosomiasis is accompanied by a profound general immunosuppression in which both suppressive t cells and macrophages (m phi) have been implicated. the present studies define changes in the m phi surface, endocytic and secretory properties, during the infection of mice by trypanosoma brucei. peritoneal m phi obtained after the control of the first wave of parasitemia displayed characteristics similar to those activated by intracellular pathogens, such as mycobacterium bovis bacillus c ... | 1983 | 6301989 |
| inefficacy of metronidazole in experimental infections of leishmania donovani, l. mexicana, and trypanosoma brucei brucei. | metronidazole has been claimed in several earlier reports to be active in human cases of leishmaniasis and trypanosomiasis. its efficacy against the protozoa causing these diseases was tested in hamsters infected with leishmania mexicana or l. donovani, and in mice infected with trypanosoma brucei brucei. in separate experiments, hamsters were either inoculated intradermally into the nose with 5 million amastigotes of l. mexicana or intracardially with 10-30 million amastigotes of l. donovani, a ... | 1983 | 6305218 |
| activation of the genes for variant surface glycoproteins 117 and 118 in trypanosoma brucei. | we have studied the activation of genes for vsgs (variant surface glycoproteins) in trypanosoma brucei (strain 427) in six independently isolated trypanosome clones; four expressing the gene for vsg 118 and two the gene for vsg 117. in all cases, gene activation is brought about by a duplicative transposition of the gene to an expression site located close to the end of a chromosome. the dna segments flanking the expression-linked extra gene copy are nearly devoid of restriction enzyme recogniti ... | 1983 | 6306248 |
| the transposition unit of variant surface glycoprotein gene 118 of trypanosoma brucei. presence of repeated elements at its border and absence of promoter-associated sequences. | at the dna level, antigenic variation in trypanosomes is brought about by the replacement of one variant surface glycoprotein (vsg) gene by another in an expression site with a strong promoter. in several cases studied, mobilization of a vsg gene for expression involves a duplication-transposition. we have determined the dna sequence of most of the transposed segment of one such vsg, the vsg 118. at the 3' side, the transposed segment ends within the end of the gene; at the 5' side, the transpos ... | 1983 | 6306255 |
| the major transcripts of the kinetoplast dna of trypanosoma brucei are very small ribosomal rnas. | the nucleotide sequence has been determined of a 2.2 kb segment of kinetoplast dna, which encodes the major mitochondrial transcripts (12s and 9s) of trypanosoma brucei. the sequence shows that the 12s rna is a large subunit rrna, although sufficiently unusual for resistance to chloramphenicol to be predicted. the 9s rna has little homology with other rrnas, but a possible secondary structure is not unlike that of the 2.5-fold larger e. coli 16s rrna. we conclude that the 12s rna (about 1230 nuc ... | 1983 | 6306559 |
| comparison of maxicircle dnas of leishmania tarentolae and trypanosoma brucei. | the conserved portions of the maxicircle dnas of leishmania tarentolae and trypanosoma brucei are organized in a basically colinear manner over a 15- to 17-kilobase region that is interrupted by two small less-homologous sequences. the most highly conserved regions are those encoding the 9s and 12s genes. an approximately 12-kilobase region directly upstream of the 12s gene in the l. tarentolae maxicircle showed no sequence homology with the t. brucei maxicircle and also was not transcribed. an ... | 1983 | 6306661 |
| tubulin genes of trypanosoma brucei: a tightly clustered family of alternating genes. | african trypanosomes are the causative agents of many medically and economically important diseases of man and domestic animals. the cell body of these blood-dwelling protozoa is enveloped with a dense layer of pellicular microtubules, which confer both motility and mechanical stability on these cells; microtubules are also important components of the flagellum. the major structural components of the microtubuli are two related proteins, alpha- and beta-tubulin. we have analyzed the genomic orga ... | 1983 | 6308633 |
| generation of overlapping labeled dna fragments for dna sequencing: a mercury-thiol affinity system. | | 1983 | 6312253 |
| tandem repetition of the 5' mini-exon of variant surface glycoprotein genes: a multiple promoter for vsg gene transcription? | activation of some variant surface glycoprotein (vsg) genes involves a duplicative transposition to an expression site, which completes the gene by addition of a mini-exon coding for the 5' 35 nucleotides of vsg mrnas. using a 22 nucleotide probe we have found some 200 copies of the mini-exon on a tandemly arranged 1.35 kb repetitive element. this repeat is highly conserved in three trypanosome species. the mini-exon on the repeat is flanked by a 5' splice site that resembles the consensus seque ... | 1983 | 6313212 |
| sequences homologous to the variant antigen mrna spliced leader are located in tandem repeats and variable orphons in trypanosoma brucei. | we have examined the organization of genomic sequences homologous to the spliced leader of trypanosoma brucei variant surface glycoprotein (vsg) mrna, using a synthetic oligodeoxynucleotide probe. these sequences are highly reiterated in the trypanosome genome and most are located in 1.4 kb units arranged in a direct tandem repeat. however, some of the 1.4 kb sequences are dispersed from the cluster(s) of tandem repeats and are flanked by non-repeat dna. the number and arrangement of these leade ... | 1983 | 6313213 |
| gene activation and re-expression of a trypanosoma brucei variant surface glycoprotein. | the expression of the trypanosoma brucei variant surface glycoprotein antat 1.1 proceeds by a mechanism that transfers a duplicated gene copy into a new genomic environment, the so-called expression site, where it will be expressed. we have isolated a genomic fragment containing the region spanning the expression site-transposon junction, and the 5' half of the coding sequence. comparing this dna segment with its template copy (basic copy) allowed us to identify the exact breaking point and indi ... | 1983 | 6313354 |
| the nucleotide sequence of a segment of trypanosoma brucei mitochondrial maxi-circle dna that contains the gene for apocytochrome b and some unusual unassigned reading frames. | the nucleotide sequence of a 2.5-kb segment of the maxi-circle of trypanosoma brucei mtdna has been determined. the segment contains the gene for apocytochrome b, which displays about 25% homology at the amino acid level to the apocytochrome b gene from fungal and mammalian mtdnas. northern blot and s1 nuclease analyses have yielded accurate map positions of an rna species in an area that coincides with the reading frame. the segment also contains two pairs of overlapping unassigned reading fram ... | 1983 | 6314266 |
| the enzymes of purine salvage in trypanosoma cruzi, trypanosoma brucei and leishmania mexicana. | we have previously shown the presence of various purine salvage enzymes in trypanosoma cruzi, including phosphoribosyltransferase, aminohydrolase, kinase, phosphorylase and hydrolase activities. we now report that a similar situation occurs in leishmania mexicana amazonensis and trypanosoma brucei brucei. in all three organisms we found higher levels of activity for the phosphoribosyltransferase enzymes than for the nucleoside kinases, suggesting a preference for the salvage of purine bases rath ... | 1983 | 6316234 |
| identification of a telomeric dna sequence in trypanosoma brucei. | a simple repetitive dna sequence in the nuclear genome of trypanosoma brucei, consisting of tandem repeats of the hexanucleotide 5' ccctaa 3', was identified as being telomeric by several criteria. this sequence was specifically labeled with t. brucei genomic dna as the template for in vitro nick translation by dna polymerase i, and was present in bal 31 nuclease sensitive, genomic restriction fragments of the large sizes expected in this organism for at least some telomeric regions. the same re ... | 1984 | 6319025 |
| structure of the growing telomeres of trypanosomes. | we have developed a method for the molecular cloning of dna adjacent to chromosome ends (telomeres). a recombinant dna clone obtained from the telomeres of the protozoan trypanosoma brucei contains large stretches of the repeat (ccctaa)n. this repeat is flanked by a larger subtelomeric repeat (29 bp in one case). these repeats account for the presence of large dna stretches not cut by restriction enzymes downstream of telomeric vsg genes. all telomeres analyzed thus far (more than 30) grow by ap ... | 1984 | 6319026 |
| subcellular distribution and partial characterization of the cyclic amp-binding proteins of trypanosoma brucei. | we assayed the cyclic amp-binding activity of trypanosoma brucei by two well established methods, such as the one of gilman (proc. natl. acad. sci. u.s.a. 67, 305-312, 1970) and ueland & doskeland (biochem. j., 157, 117-126, 1976). the results indicate that the former technique underestimated the total amount of cyclic amp bound by t. brucei homogenates by up to 7.5 fold. similar results were obtained with other trypanosomatidae such as leishmania tropica, and crithidia luciliae. the bulk of the ... | 1984 | 6321981 |
| variant antigen genes of trypanosoma brucei: genomic alteration of a spliced leader orphon and retention of expression-linked copies during differentiation. | variant surface glycoprotein (vsg) gene expression in trypanosoma brucei involves not only the sequential activation of individual vsg genes during mammalian bloodstream stage antigenic variation but also the regulation of gene expression during cyclic transmission through alternate mammalian and insect hosts. in the bloodstream stage, transcriptional activation of many vsg genes is correlated with the appearance of an additional copy of the gene in a novel genomic location, the expression-linke ... | 1984 | 6322164 |
| distinction of african trypanosome species using nucleic acid hybridization. | we have performed restriction endonuclease digestion of nuclear dnas, combined with gel electrophoresis and molecular hybridization to characterize different trypanosoma brucei brucei stocks and to identify trypanosome species. cloned dna complementary to the messenger rnas (mrnas) for different variable surface glycoproteins (vsgs) of t. b. brucei stock lump 227 was used to examine differences in genomic dnas from t. b. brucei stocks and from various other trypanosome species. these cdna reagen ... | 1984 | 6324058 |
| differential size variations between transcriptionally active and inactive telomeres of trypanosoma brucei. | we have studied the genes coding for the variant-specific surface antigen (vsa) in a series of seven trypanosome clones derived from antat 1.1: 1.1 leads to 1.3 leads to 1.6 leads to 1.16 leads to 1.1c leads to 1.3b leads to 1.18 these genes are all telomeric (1-5), and their surrounding, although sometimes similar, differs in each case. the length between these antigen genes and the corresponding dna end appears to increase at each antigenic switch, with however occasional sharp size reductions ... | 1983 | 6324074 |
| telomere conversion in trypanosomes. | activation of the gene coding for variant surface glycoprotein (vsg) 118 in trypanosoma brucei proceeds via a duplicative transposition to a telomeric expression site. the resulting active expression-linked extra copy (elc) is usually flanked by dna that lacks sites for most restriction enzymes and that is thought to interfere with the cloning of the elc as recombinant dna in escherichia coli. we have circumvented this problem by cloning an aberrant 118 elc gene, flanked at the 3'-side by at lea ... | 1983 | 6324075 |
| an african trypanosome variant surface glycoprotein gene whose expression is not activated by duplication. | a variant surface glycoprotein (vsg) of trypanosoma brucei is encoded by a gene whose expression is not governed by duplication-transposition. there are two copies of this gene. the 5' flanking regions of the two genes are indistinguishable by restriction mapping, although each possesses approximately 5-10 kbp of dna which is devoid of restriction sites. all restriction enzymes tested appeared to cut genomic dna at a uniform distance 3' of the gene. this, coupled with the observed sensitivity of ... | 1983 | 6324082 |
| the 5'-limit of transposition and upstream barren region of a trypanosome vsg gene: tandem 76 base-pair repeats flanking (taa)90. | we have cloned and sequenced a portion of the region upstream of an expressed vsg gene of trypanosoma brucei. this "expression-linked copy" arose through the duplication and transposition of a silent, "basic copy" of the gene to an expression site. comparison of the sequences surrounding the 5'-end of the transposed segment in the two loci indicates the 5'-limit of transposition lies within the first (3'-most) of three repeated segments found at this position in the basic copy locus. these highl ... | 1984 | 6324125 |
| two mechanisms of expression of a predominant variant antigen gene of trypanosoma brucei. | african trypanosomes evade the host immune response by periodically switching their variant surface glycoprotein (vsg) coat. the resulting, serologically distinct variant antigenic types (vats) appear in a loosely ordered sequence and those arising early in infections are termed predominant vats. vat switching reflects the successive transcriptional activation of single vsg genes from a large repertoire. activation of some vsg genes is accomplished by duplication of a previously silent basic cop ... | 1984 | 6325951 |
| complete nucleotide sequence of an unusual mobile element from trypanosoma brucei. | the complete nucleotide sequence of a mobile element from trypanosoma brucei is presented along with the sequence of its target site, which shows that the insertion has generated a 7 base pair direct repeat. the cloned copy of the element is a dimeric structure, one end of each monomer consisting of a stretch of 14 a residues preceded by a putative trypanosome polyadenylation signal. six base pairs of dna of unknown origin are found in the dimer between the two copies of the element. evidence su ... | 1984 | 6327058 |
| comparison of the expression-linked extra copy (elc) and basic copy (bc) genes of a trypanosome surface antigen. | a recombinant clone of an expression-linked extra copy (elc) gene of a trypanosome-variable surface glycoprotein was sequenced. in addition the sequences of the corresponding cdna and portions of the two basic copy genes were determined. comparison of these sequences reveals that the 5' boundary of the elc-transposed segment (2.2 kb) occurs within a repetitive sequence about 700 bp upstream from the start codon of the coding sequence. this sequence does not contain internal symmetries and is not ... | 1983 | 6327735 |
| mitochondrial dna of an african trypanosome. | the maxicircles of african trypanosome kdna are the genetic equivalent of other mitochondrial dnas, but the function of minicircles is unknown. the maxicircle of trypanosoma brucei 164 encodes conventional mitochondrial gene products and is largely but not completely transcribed. nucleotide sequence analysis of a region not found to be transcribed revealed numerous translation termination codons in all three reading frames of both strands and numerous inverted repeats, suggesting that this segme ... | 1983 | 6327737 |
| interaction of high-density lipoprotein with trypanosoma brucei: effect of membrane stabilizers. | the specific lysis of bloodstream trypanosomes by serum from a nonpermissive mammalian host is the result of interaction between the serum trypanocidal factor (high-density lipoprotein) and the trypanosome surface. the studies described in this paper attempt to define further the mode of action of this cytotoxic lipoprotein. the binding of high-density lipoprotein to trypanosoma brucei was instantaneous at 4 degrees c and readily reversible. binding was not mediated by the surface glycoprotein a ... | 1983 | 6327740 |
| modification of telomeric dna in trypanosoma brucei; a role in antigenic variation? | expression of surface antigen genes in trypanosoma brucei occurs at expression sites located near telomeres. since only one antigen is produced at a time, a mechanism must exist to prevent the simultaneous activity of multiple expression sites. here we report that psti and pvuii restriction sites in silent telomeric antigen genes are partially uncleavable , presumably as a consequence of dna modification. the modification, which is absent in transcribed genes but returns after gene inactivation, ... | 1984 | 6328412 |
| characterization of the 1.35 kilobase dna repeat unit containing the conserved 35 nucleotides at the 5'-termini of variable surface glycoprotein mrnas in trypanosoma brucei. | we have cloned and determined the sequence of the 1.35 kb trypanosome dna repeat unit that contains the conserved 35 nucleotides found at the 5'-ends of variable surface glycoprotein (vsg) mrnas and present in many other trypanosome rnas. our data indicate that the genomic repeats, estimated by others to be present in 200-250 copies in the haploid genome (18, 21), are structurally very highly conserved but with dispersed point changes. the 1.35 kb repeat unit has an unusual stretch of multiple r ... | 1984 | 6330689 |
| iron-containing superoxide dismutase from crithidia fasciculata. purification, characterization, and similarity to leishmanial and trypanosomal enzymes. | leishmania tropica, trypanosoma brucei, trypanosoma cruzi, and crithidia fasciculata have superoxide dismutases which are insensitive to cyanide and sensitive to peroxide and azide, properties characteristic of iron-containing superoxide dismutase. studies on the superoxide dismutase of c. fasciculata have revealed that: 1) the enzyme is located in the cytosol; 2) isozymes exist; 3) the major superoxide dismutase isozyme (superoxide dismutase 2) has mr approximately equal to 43,000 and consists ... | 1983 | 6336744 |
| an em study on cerebral trypanosomiasis in rodents and primates. | | 1983 | 6337775 |
| a physiological mechanism to explain pathogenesis in african trypanosomiasis. | | 1983 | 6337778 |
| extravascular and vascular distribution of trypanosoma b. gambiense in microtus montanus after cyclical transmission. | | 1983 | 6337779 |
| characterization of satellite dna in trypanosoma brucei and trypanosoma cruzi. | we have determined the properties of the simple-sequence satellite dnas from two protozoa, trypanosoma brucei and trypanosoma cruzi. the t. brucei satellite dna contains 29 mol% guanine plus cytosine and is made up of long tandem arrays of a 177 base-pair repeat. sequence heterogeneity in these repeats is limited and restricted to certain positions as shown by sequence analysis, restriction enzyme digestion and two-dimensional analysis of nucleotides bordering the alui and hhai recognition sites ... | 1983 | 6345792 |
| sexual processes in the kinetoplastida. | the commonly held view that the kinetoplastida, and in particular trypanosomes, are asexual is largely derived from the principle that an organism is asexual until proved sexual. if the basis for this view is examined in detail, it largely arises from the lack of morphologically distinguishable gametes, the difficulties encountered in visualizing chromosomes and a few experiments, using drug-resistant stocks, in which no recombination between stocks could be demonstrated. while it is clear that ... | 1983 | 6346233 |
| the polypeptide profiles of strains of the trypanosoma subgenera schizotrypanum and trypanozoon: peptideme characterization. | examination, by sds-page, of the polypeptide profiles of 36 brazilian strains of trypanosoma (schizotrypanum) cruzi has revealed five peptidemes (subpopulations having similar polypeptide profiles) recognizing differences not apparent from zymodeme analysis. t. cruzi zymodeme (z)1 has been subdivided into peptidemes 3, 4 and 5 (one example of z2 was included in peptideme 5). peptideme 1 consisted mostly of z2 strains except for one example each of z1 and z3. one strain of z2 (tc 003) was suffici ... | 1983 | 6353688 |
| [antigenic variation of trypanosoma brucei with reference to the serodiagnosis of sleeping sickness]. | | 1983 | 6364615 |
| expression of a trypanosoma brucei brucei variant antigen in escherichia coli. | a cdna library derived from antigenically homogeneous bloodstream stage trypanosoma brucei brucei was screened with an antiserum directed against the variant surface antigen (vsa) using an enzyme-linked filter immunoassay. several recombinant clones were detected and the clone giving the most intense reaction was further analyzed. it contained a vsa-specific cdna insert and synthesized a protein of the expected molecular weight bearing vsa determinants. the nucleotide sequence of the insert was ... | 1984 | 6366543 |
| a comparative study of the proteolytic enzymes of trypanosoma brucei, t. equiperdum, t. evansi, t. vivax, leishmania tarentolae and crithidia fasciculata. | four types of proteolytic activity were detected in the bloodstream form of each of the four trypanosoma species: (i) hpaase, active on hide powder azure and detected on polyacrylamide gels containing denatured haemoglobin; (ii) azcase, active on azocasein; (iii) type 1, active on the chromogenic peptide n-benzoyl-l-prolyl-l-phenylalanyl-l-arginine p-nitroanilide in the presence of dithiothreitol, and (iv) type 2, active against several nitroanilide derivatives in the absence of dithiothreitol. ... | 1983 | 6366547 |
| [characterization of the antar 2 antigen of trypanosoma brucei brucei]. | | 1984 | 6375591 |
| the surface of the african trypanosomes. | the african trypanosomes bear on the outside of their cell membrane a single 10-15 nm thick coat of a glycoprotein. this glycoprotein may differ in structure in the predominant populations of parasitemic waves found in relapsing infections. variant specific glycoprotein (vsg) range in mw between 53,000-63,000 d and may have variable amounts of carbohydrate attached at one, two, or several loci. such differences in carbohydrate content may account in part for their range in molecular size. approx ... | 1984 | 6376790 |
| lipoprotein lipase suppression in 3t3-l1 cells by a haematoprotozoan-induced mediator from peritoneal exudate cells. | lysates of the haematoprotozoa trypanosoma brucei or plasmodium berghei stimulated murine peritoneal exudate cells to release a mediator, which suppressed lipoprotein lipase activity in differentiating 3t3-l1 preadipocytes. the parasite-induced mediator suppressed the activity of cell surface lipoprotein lipase up to 39% in a dose dependent manner. by impairing the activity of cell surface lipoprotein lipase, this mediator acts to inhibit the uptake of fatty acid, and ultimately the accumulation ... | 1984 | 6377200 |
| genetics of resistance to the african trypanosomes. iv. resistance of radiation chimeras to trypanosoma rhodesiense infection. | the cellular bases of resistance to the african trypanosomes were examined in inbred mice. as part of these studies, reciprocal bone marrow cell transplants were performed between h-2 compatible mice which differ in relative resistance to trypanosoma brucei rhodesiense infection. survival times, parasitemias and igm antibody responses to the surface antigen of the infecting variant type were measured in these semiallogeneic bone marrow chimeras. relatively resistant c57bl/10 mice, intermediate a ... | 1984 | 6378394 |
| induction of anti-intermediate filament antibody in rabbits experimentally infected with trypanosoma brucei brucei. | | 1984 | 6378766 |
| antibody levels during bovine hemoparasitic diseases: trypanosomiasis, anaplasmosis, and babesiosis. | | 1983 | 6399967 |
| activation of genes for variant surface glycoproteins in trypanosomes. | | 1984 | 6400772 |
| the role of threonine in the metabolism of acetyl coenzyme a by trypanosoma brucei brucei. | | 1983 | 6403282 |
| locations of the six disulphide bonds in a variant surface glycoprotein (vsg 117) from trypanosoma brucei. | the locations of the six disulphide bonds and the single free cysteine residue in a variant surface glycoprotein, vsg 117, from the african trypanosome trypanosoma brucei have been determined to be cys-14--cys-140, cys-121--cys-182, cys-389--cys-404, cys-398--417, cys-447--cys-461 and cys-455--cys-468. cys-244 bears the single thiol group, which is unreactive towards 2-nitro-5-thiocyanobenzoate in the native molecule and is probably buried. biosynthetically incorporated [35s]cysteine aided the l ... | 1983 | 6405739 |
| characterisation of the cross-reacting carbohydrate groups on two variant surface glycoproteins of trypanosoma brucei. | the nature of the cross-reacting groups on two variant surface glycoproteins of trypanosoma brucei has been investigated after isolation of glycopeptides produced by extensive proteolytic digestion of the proteins. one variant yielded two glycopeptides after pronase digestion, one of which was the glycosylated c-terminal aspartic acid. in a second variant there are two carbohydrate groups close to the c-terminus. considerable heterogeneity in the size of the sugar attached to an asparagine resid ... | 1983 | 6410233 |
| micro-counterimmunoelectrophoresis: a rapid screening technique for trypanosomiasis. | a rapid and economical micro-counterimmunoelectrophoresis (mcie) test, for antibody to trypanosome antigens, has been developed which may prove useful in trypanosomiasis surveillance. mcie was more sensitive and more rapid than immunodiffusion (id). serum samples from trypanosome-infected rabbits and cattle (nigerian and gambian), from kuwaiti dogs and camels, from ivory coast sleeping sickness patients, from brazilian patients with chagas's disease, plus mouse-anti-malaria sera have been tested ... | 1983 | 6415874 |
| comparative aspects of purine metabolism in some african trypanosomes. | some enzymes of purine salvage were detected in the cell-free preparations from bloodstream forms of african trypanosomes: trypanosoma vivax; t. brucei and t. congolense. extracts of trypanosomes cleave adenosine and inosine hydrolytically except in t. congolense where adenosine cleavage was mediated by a phosphorylase. all the trypanosomes apparently lacked adenosine deaminase. adenine aminohydrolase was found only in t. vivax while adenosine monophosphate deaminase was detected in t. brucei an ... | 1983 | 6419098 |
| threonine uptake in trypanosoma brucei. | threonine uptake by the parasitic protozoan trypanosoma brucei has been assessed using an oil-phase separation technique for measuring rapid amino acid fluxes. it was shown that the storage conditions for the organism were critical for the production of reproducible data. using this method it has been shown that threonine uptake occurs rapidly, being linear for less than 30 s at 37 degrees c in contrast with previous reported results. kinetic analysis of threonine uptake at 25 degrees c and at p ... | 1984 | 6431284 |
| new drug combination for experimental late-stage african trypanosomiasis: dl-alpha-difluoromethylornithine (dfmo) with suramin. | using a previously described mouse model of late-stage african trypanosomiasis (i.e., involvement of the central nervous system), we demonstrate that a combination of dl-alpha-difluoromethylornithine (dfmo) and suramin is curative. in the curative protocol, dfmo is given as a 2% solution in the drinking water for 14 days and suramin is administered as a single dose (20 mg/kg intravenously) on day 1 of dfmo administration. since: 1) dfmo has very low toxicity, 2) suramin is one of the least toxic ... | 1984 | 6439061 |
| the istar 1 serodeme of trypanosoma brucei: development of a new serodeme. | an extensive serodeme of sequentially-isolated antigenic variants of african trypanosomes has been produced from both syringe-passaged and cyclically-transmitted trypanosoma brucei of the istar 1 clone derived from eatro 164. the majority of the antigenic variants were isolated from chronically-infected deer mice (peromyscus leucopus). the pattern of parasitemias during the course of infections initiated with syringe-passaged trypanosomes differed from those initiated with cyclically-transmitted ... | 1984 | 6439844 |
| nonvariant antigens limited to bloodstream forms of trypanosoma brucei brucei and trypanosoma brucei rhodesiense. | the presence of nonvariant antigens (nvas) limited to bloodstream forms of trypanosoma brucei brucei and trypanosoma brucei rhodesiense was demonstrated for the first time by immunodiffusion and immunoelectrophoresis. noncloned and cloned populations were employed in preparation of polyclonal antisera in rabbits and of antigens to be used in the immunologic reactions. the nvas could be shown best in systems in which hyperimmune rabbit sera (adsorbed with procyclic forms to eliminate antibodies a ... | 1984 | 6439856 |
| comparison of the levels of autofluorescence caused by fixatives in fluorescence assay on trypanosomes. | | 1984 | 6441838 |
| glycoproten biosynthesis in trypanosoma brucei. the glycosylation of glycoproteins located in and attached to the plasma membrane. | 1. glycosyltransferase activity incorporating n-[14c]acetylglucosamine ([14c]glcnac) from uridine diphosphate n-[14c]acetylglucosamine (udp-[14c]glcnac) into endogenous proitein acceptors was localized primarily in the plasma membrane of trypanosoma brucei. 2. the acceptor site for the nucleotide sugar was further localized exclusively to the cytoplasmic face of the plasma membrane. 3. the glycosyltransferase produced elongation of the growing oligosaccharide chains while they were attached to t ... | 1980 | 6447596 |
| trypanosoma brucei: preparation and some properties of a multienzyme complex catalysing part of the glycolytic pathway. | | 1980 | 6447613 |
| malate dehydrogenase in african trypanosomes--i. preliminary studies with t. brucei. | | 1980 | 6448757 |
| murine t lymphocyte specificity for african trypanosomes. ii. suppression of the t lymphocyte proliferative response to trypanosoma brucei by systemic trypanosome infection. | previously, we described a system allowing the study of murine t cell-dependent proliferative responses to trypanosoma brucei antigens. it was observed that t. brucei-specific t cells could be demonstrated in the regional lymph nodes of primed mice for only 2 to 3 weeks following priming. the results of the present study indicate that this inability to demonstrate a long-lived memory response is due to an immunosuppressive effect of the resulting t. brucei infection. the exact mechanism of the s ... | 1981 | 6458434 |
| the acquisition of human serum resistance during cyclical passage of a trypanosoma brucei brucei clone through glossina morsitans morsitans maintained on human serum. | | 1984 | 6464124 |
| histopathological findings in mini-pigs infected with different strains of trypanosoma brucei. | two pigs infected with trypanosoma brucei gambiense developed low parasitemia which became undetectable after 6 months; on autopsy 13 months after infection they showed no histopathological alterations. --five of six pigs infected with a trypanosoma brucei brucei strain from the ivory coast developed low parasitemia (up to about antilog 6.5 per ml of blood) which became progressively lower but was detectable up to one year after infection. on autopsy they showed interstitial myocarditis and meni ... | 1984 | 6464185 |
| behaviour of a trypanosoma brucei brucei stock (stib 348c) in mice. 4. different course of primary parasitemia in trypanosome variants of different virulence. | in three types of trypanosomes with low virulence, trypanosome numbers increased by a factor of 18-21 per day on average during prepatency and by a factor of 70-219 on average from the first to second day of patency. by contrast, a very virulent trypanosome variant showed an average increase of trypanosome numbers per day by 32 and 28 during prepatency and early patency, respectively. --in detailed studies, trypanosomes of low virulence exhibited a rapidly rising parasitemia in early patency whi ... | 1984 | 6464186 |
| the in vitro trypanocidal activity of n-substituted p-benzoquinone imines: assessment of biochemical structure-activity relationships using the hansch approach. | it has previously been found that naphthoquinones can potentiate the rate of hydrogen peroxide production by mitochondrial preparations of trypanosoma brucei brucei and that organisms treated with naphthoquinones are more susceptible to lysis, especially in the presence of compounds such as heme, which promote the homolytic cleavage of hydrogen peroxide. we have evaluated the lytic effect of various n-substituted p-benzoquinone imines both in vitro and in vivo and have attempted to correlate the ... | 1984 | 6470049 |
| 6 a-resolution x-ray structure of a variable surface glycoprotein from trypanosoma brucei. | the variable surface glycoprotein (vsg) is the predominant component of the surface coat of the african trypanosome. the expression of antigenically distinct vsgs on minor populations during infection allows the parasite to escape the host immune response. purification of the protein is facilitated by the enzymatic release of a soluble form of vsg (svsg) which occurs on cell lysis. the soluble form is a dimer with an approximate molecular weight of 120,000-130,000. partial proteolysis of svsg re ... | 1984 | 6472475 |
| alpha-helical coiled-coil structures of trypanosoma brucei variable surface glycoproteins. | we have used electron microscopy to examine purified intact variable surface glycoproteins (vsgs) from clones derived from two distinct stocks of trypanosoma brucei. the vsg molecule from mitat 1.2 has a large elongated domain consistent with the shape of the dimeric n-terminal domain determined by x-ray analysis (see preceding paper), and a heretofore unseen short, thin fibrous tail presumed to be the c-terminal domain. electron microscopy on ditat 1.3, however, indicates a morphology quite dis ... | 1984 | 6472476 |
| the role of the spleen in trypanosoma brucei brucei infection in dogs. | | 1984 | 6475405 |
| pyruvate kinase: a carnitine-regulated site of atp production in trypanosoma brucei brucei. | pyruvate kinase activity in trypanosoma brucei brucei is stimulated in the presence of l-carnitine and is inhibited by acetyl coa, atp or the atp-mg2+ complex. increased pyruvate kinase activity is associated with stimulation of atp synthesis in the presence of l-carnitine. there is evidence that carnitine stimulates pyruvate kinase activity indirectly by removing the inhibitory modulator acetyl coa as a result of the carnitine acetyl transferase (cat) also present in the trypanosomes. | 1984 | 6478790 |
| messenger rna pieced together. | | 1984 | 6482959 |
| [relations among 3 antigen repertoires of trypanosoma brucei brucei]. | | 1984 | 6486900 |
| chromosome rearrangements in trypanosoma brucei. | we have studied chromosome rearrangements in t. brucei using pulsed field gradient gel electrophoresis to separate chromosome-sized dna molecules. we detect size changes in a set of small chromosomes (200-700 kb) at a frequency of 10(-5) to 10(-6) per trypanosome division; this results in a radical difference in the size distribution of these chromosomes in different t. brucei isolates. several of these chromosome rearrangements can be related to a change in the expression of surface antigen gen ... | 1984 | 6488319 |
| simultaneous purification of hexokinase, class-i fructose-bisphosphate aldolase, triosephosphate isomerase and phosphoglycerate kinase from trypanosoma brucei. | a method is presented for the simultaneous purification of hexokinase, fructose-bisphosphate aldolase, triosephosphate isomerase and phosphoglycerate kinase, and the partial purification of glycerol-3-phosphate dehydrogenase (nad+), 6-phosphofructokinase, glucosephosphate isomerase, and glycerol kinase from trypanosoma brucei. as a first step, the glycosomes, microbody-like organelles of trypanosomatidae, containing almost exclusively enzymes involved in glucose and glycerol metabolism [opperdoe ... | 1984 | 6489338 |
| light scattering and correlation measurement. | | 1984 | 6489595 |
| the measurement of motility in micro-organisms and its biochemical significance. | | 1984 | 6489597 |
| preliminary crystallographic studies of triosephosphate isomerase from the blood parasite trypanosoma brucei brucei. | crystals of triosephosphate isomerase (ec 5.3.1.1) from trypanosoma brucei brucei have been grown. these crystals diffract to at least 2 a, even after 60 hours of exposure to x-rays. the space group is p212121, with cell dimensions a = 112.4 a, b = 97.8 a, c = 48.0 a. there is one dimer per asymmetric unit. | 1984 | 6492157 |
| haemagglutinins and parasite agglutinins in haemolymph and gut of glossina. | agglutinating activity was found in the haemolymph and in extracts of midgut and hindgut of glossina austeni against calf, guinea pig and chicken erythrocytes for the first time. trypanosoma brucei procyclic forms were also agglutinated by midgut and hindgut extracts, but not by haemolymph. the 3 fractions tested failed to react with erythrocytes of four other vertebrates and other trypanosomatids (leishmania hertigi and crithidia fasciculata) examined. the reciprocal titre of agglutinating acti ... | 1984 | 6495384 |
| trypanosoma brucei-induced blockage of expulsion of echinostoma revolutum and of homologous e. revolutum resistance in mice. | experiments were designed to study the effect of trypanosoma brucei on the expulsion of echinostoma revolutum and on the development and maintenance of homologous e. revolutum resistance in the mouse. t. brucei given 3, 2, and 1 wk before and 1 wk after infection with e. revolutum completely inhibited the expulsion of the e. revolutum worm burden for a period of at least 6 wk following infection, and t. brucei given 2 or 3 wk after infection with e. revolutum conferred a significant delay in the ... | 1984 | 6502358 |
| enzyme variation in trypanosoma brucei spp. i. evidence for the sub-speciation of trypanosoma brucei gambiense. | three groups of stocks of trypanosoma brucei ssp, defined by the criteria of host, human serum resistance and place of isolation as t. b. gambiense, t. b. brucei (nigeria) and t. b. brucei/rhodesiense (non-gambiense, uganda) were screened for electrophoretic variation at 20 enzyme loci. one enzyme (peptidase c) was found to differentiate all t. b. gambiense stocks from the other t. brucei stocks and, taken together with specific variants of 5 other enzymes, could be used to unambiguously define ... | 1984 | 6504561 |
| delayed expulsion of hymenolepis diminuta in trypanosoma brucei infected mice. | an experiment was conducted to study the effect of trypanosoma brucei on the expulsion of hymenolepis diminuta in the mouse. the study showed that t. brucei given 8 days before infection with h. diminuta resulted in a significant delay in the expulsion of the h. diminuta worm burden. this finding is suggested to be due to the immunosuppressive effect of the trypanosome. | 1984 | 6506844 |
| serodiagnosis of trypanosomiasis in dromedary camels using a card agglutination test set (testryp catt). | | 1984 | 6508393 |
| subcellular localization of photoreactive ethidium analogs in trypanosoma brucei by fluorescence microscopy. | to identify the in vivo targets of the trypanocide, ethidium bromide, the fluorescent staining of t. brucei was examined for a series of ethidium analogs using fluorescence microscopy. determination of the biological targets for most drugs is limited by the reversible nature of their interactions. to overcome this limitation, photoaffinity (azido) analogs of ethidium, which are capable of covalent attachment with photoactivation, were used to identify the ethidium binding sites within the parasi ... | 1984 | 6512635 |
| in vitro cultivation of trypanosoma (t.) brucei bloodstream forms using cell lines and sera from african wild bovidae. | | 1984 | 6512650 |
| studies on the influence of non-steroidal anti-inflammatory drugs upon trypanosomiasis in goats and sheep. | the non-steroidal anti-inflammatory drug (nsaid) flurbiprofen caused a rise in parasitaemia in goats infected with trypanosoma vivax, trypanosoma congolense and trypanosoma brucei. all trypanosome-infected goats treated with flurbiprofen showed many dividing trypanosomes. this also included the short-stumpy forms of t. brucei. in t. vivax-infected goats flurbiprofen treatment resulted in 100% mortality in the acute and chronic stages of the infection. the increase in parasitaemia of t. brucei in ... | 1984 | 6512919 |
| characterization of spermidine synthase from trypanosoma brucei brucei. | spermidine synthase from trypanosoma brucei brucei was characterized and found to be similar to spermidine synthase from other sources. the km for putrescine was found to be 0.2 mm and the km for decarboxylated s-adenosylmethionine 0.1 microm. the approximate molecular weight of the enzyme was 74 000 as determined by a combination of molecular sieve chromatography and sucrose density gradient centrifugation. spermidine synthase activity was markedly inhibited in vitro by dicyclohexylamine (50% i ... | 1984 | 6513985 |
| the maxicircle of trypanosoma brucei kinetoplast dna encodes apocytochrome b. | the region of the maxicircle of trypanosoma brucei kinetoplast dna which hybridizes at low stringency with the apocytochrome b gene of saccharomyces cerevisiae has been identified and cloned. the nucleotide sequence of a 1.7 kb segment of this region is reported. this segment contains a single long open reading from capable of coding for a 350 amino acid protein with substantial homology to apocytochromes b of other species. the trypanosome protein is considerably more distantly related to other ... | 1984 | 6513991 |
| alpha-amanitin-insensitive transcription of variant surface glycoprotein genes provides further evidence for discontinuous transcription in trypanosomes. | many, if not all, mrnas in t.brucei start with the same sequence of 35 nucleotides, separately encoded in clustered so-called mini-exon repeats. from these mini-exon repeats a 141-nt precursor rna with the 35-nt sequence at its 5' end is transcribed. indirect evidence suggests that this rna is linked in a second step to pre-mrna transcripts. we have studied the sensitivity of rna synthesis to alpha-amanitin in isolated trypanosome nuclei. transcription of several protein coding genes is almost c ... | 1984 | 6514580 |
| the use of 2-substituted 5-nitroimidazoles in the treatment of chronic murine trypanosoma brucei infections with central nervous system involvement. | chronic infections of trypanosoma brucei gvr 35/2 in mice, normally relapse after conventional chemotherapy because infective trypanosomes in the brain escape the action of the drug and are able to multiply and eventually re-establish a parasitaemia. however, if treatment consists of a single dose of 1 x 20 mg/kg suramin followed 3 or 4 days later by a 2-substituted 5-nitroimidazole, given intraperitoneally, either as a single dose or as a course of daily injections, relapses rarely occur and th ... | 1984 | 6524019 |
| [parasitological, clinical and serological findings in dahomey cattle experimentally infected with trypanosoma congolense and t. brucei]. | | 1984 | 6525154 |
| transport of alpha-aminoisobutyrate into trypanosoma brucei brucei. | the uptake of alpha-aminoisobutyrate (aib) by washed cell suspensions of bloodstream forms of trypanosoma brucei brucei has been shown to be an energy-dependent process. no metabolism of aib was detected under conditions leading to a 100-fold accumulation of aib within the organism. kinetic studies revealed that aib uptake involved two components; that operating at low substrate concentrations had an apparent km of 4.6 mm. experiments with ionophores such as gramicidin and carbonylcyanide m-chlo ... | 1984 | 6527126 |
| a ph-stat method for studying glycolysis in trypanosoma brucei. | | 1984 | 6527180 |
| [characterization of the vector capacity of glossinia morsitans morsitans (diptera: glossinidae) towards trypanosoma brucei brucei eatro 1125 (antar 1)]. | | 1984 | 6529273 |
| detection of circulating trypanosomal antigens by enzyme immunoassay. | antisera raised against trypanosoma evansi and t. congolense were used in a double antibody sandwich enzyme immunosorbent assay (elisa) to detect trypanosomal antigens in sera from experimentally infected rabbits and goats. assays quantitated using reference antigen preparations and the homologous antisera showed that antigens could be detected at protein concentrations of 1.5 microgram ml-1. the antisera also cross-reacted with soluble antigens prepared from t. brucei and t. vivax at similar pr ... | 1984 | 6532328 |