Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| telomere interactions may condition the programming of antigen expression in trypanosoma brucei. | the antat 1.1 antigen type typically occurs late in a chronic infection by the eatro 1125 stock of trypanosoma brucei. the antat 1.1 gene, which is located 24 kb from a chromosome end, seems exclusively expressed by acting as a donor in gene conversion events targeted to the telomeric expression site. we report that this gene is sufficiently provided with the homology blocks required for recombination with the expression site, and is not interrupted by stop codons up to the 3' block of homology. ... | 1990 | 2323332 |
| solubilization and partial purification of glycerol-3-phosphate oxidase from mitochondria of trypanosoma brucei. | 1990 | 2323400 | |
| the 5s ribosomal rna genes of crithidia fasciculata. | 1990 | 2325709 | |
| identification and sequence analysis of the ribosomal dna promoter region of crithidia fasciculata. | we have identified the promoter region of the large ribosomal dna repeat unit of crithidia fasciculata by northern blotting and nuclear run-on analyses. these data show that transcription starts approximately 1 kb upstream of the 18s rrna gene. s1 protection experiments and sequence analysis of this area resulted in a precise localization of the start site. we have been unable to identify conserved sequence element(s) by a direct comparison of the crithidial rna polymerase i promoter region and ... | 1990 | 2326181 |
| variant surface glycoprotein of trypanosoma brucei brucei antat 1.1: influence of the isolation conditions upon the disulfide linked dimer/monomer ratio. | 1. using the variant surface glycoprotein (vsg) isolation procedure described by baltz et al. ([1976] ann. immunol. (inst. pasteur) 127 c, 761-774) which involves suspension of the trypanosomes in a ph 5.5 buffer, the antwerpen trypanozoon antigenic type (antat) 1.1 vsg is mainly obtained as a disulfide linked dimeric form with a trace amount of a monomeric form. 2. the use of a parasite suspension buffer at ph 7.0 results in a slight decrease of the vsg dimer/monomer ratio. 3. ph 5.5 and 7.0 su ... | 1990 | 2328568 |
| nucleotide sequence of a full-length cdna coding for the ribosomal l44 protein of trypanosoma brucei. | 1990 | 2339065 | |
| direct in vitro isolation of trypanosoma brucei brucei and t. b. evansi from disease hosts with low parasitaemia. | three stocks of trypansoma brucei brucei and two stocks of t. b. evansi were isolated directly from host animals with a low parasitaemia. cultures were initiated under axenic conditions and/or in co-cultivation with different feeder layer cells using a modified eagle's mem. under axenic conditions, ham's f-12, iscove's modified dulbecco medium and sfre 199-2 medium were also suitable, whereas rpmi 1640, and leibovitz l-15 medium were not. the method described was sensitive and detected parasites ... | 1990 | 2339248 |
| transcription of the procyclic acidic repetitive protein genes of trypanosoma brucei. | the procyclic acidic repetitive protein (parp) genes of trypanosoma brucei encode a small family of abundant surface proteins whose expression is restricted to the procyclic form of the parasite. they are found at two unlinked loci, parpa and parpb; transcription of both loci is developmentally regulated. the region of homology upstream of the a and b parp genes is only 640 base pairs long and may contain sequences responsible for transcriptional initiation and regulation. transcription upstream ... | 1990 | 2342468 |
| the relationship between dietary energy levels and the severity of trypanosoma brucei infection in growing pigs. | growing pigs were placed on high, medium and low planes of dietary energy and were infected with a virulent strain of trypanosoma brucei. during an 8-week period post-infection (p.i.), the respective liveweight gains by infected pigs on high, medium and low energy levels were 52.1, 21.2 and 38.5%, respectively, of the corresponding gains by non-infected control pigs. there was a fall in red blood cell values p.i. which worsened with decreasing energy levels. leucocytosis was observed in all infe ... | 1990 | 2343530 |
| population genetics of trypanosoma brucei and the epidemiology of human sleeping sickness in the lambwe valley, kenya. | numerical taxonomy was used to review isoenzyme variation in isolates of trypanosoma brucei obtained from cattle, tsetse, humans and wildlife from the lambwe valley, kenya. from isoenzyme information alone, it was possible to classify isolates as to source through the use of linear discriminant functions analysis, with an error rate of only 2% in humans, and 14% over all groups. differentiation was mostly dependent on patterns in the enzymes asat, pep1, and icd. parasites from non-human sources, ... | 1990 | 2345657 |
| variant-specific trypanolytic antibodies in sera from patients infected with trypanosoma brucei rhodesiense. | infections with salivarian trypanosomes are characterized by the successive development of parasite populations of distinct variable antigen types (vats), the corresponding antibodies accumulating in the blood of the host. sixty vats had been cloned during previous studies on variable antigen repertoires of trypanosoma brucei rhodesiense; 12 of these were selected for immunolysis tests against 85 sera from t.b. rhodesiense patients in busoga (uganda). one variant, etat 1/1, reacted with 59 out o ... | 1990 | 2347032 |
| the optimisation of immunoglobulin secretion in vitro by mouse spleen cells and hybridoma cells. | optimal culture conditions and cell densities for antibody production by spleen cells from mice infected with trypanosoma brucei, and by hybridoma cells, were assessed in vitro by a silver-immunogold (sig) blot technique and an enzyme-linked immunosorbent assay (elisa). the blot assay measured the proportion of secreting cells in the population and the elisa measured the quantity of synthesised and secreted immunoglobulin (ig) in cell lysates and in 3-h culture supernatants. marked inhibition of ... | 1990 | 2347604 |
| differentiation of trypanosoma brucei bloodstream trypomastigotes from long slender to short stumpy-like forms in axenic culture. | an axenic cultivation system was used to study the differentiation of trypanosoma brucei bloodstream forms from long slender to short stumpy-like forms. trypanosomes in the logarithmic phase are similar to long slender bloodstream forms freshly isolated from infected mice, differing only in the rate of oxygen uptake. in contrast, trypanosomes in the stationary phase show a decreased level of glucose oxidation, express pyrroline-5-carboxylate reductase (proline oxidase), are inhibited in oxygen u ... | 1990 | 2348830 |
| isolation of a highly enriched plasma membrane fraction of trypanosoma brucei by free-flow electrophoresis. | a procedure is described whereby a highly enriched plasma membrane fraction was isolated from trypanosoma brucei by the technique of preparative free-flow electrophoresis. the purity of the plasma membrane fraction was monitored by electron microscopy and by marker enzymology, and is compared to those obtained by previous methods. proteins associated with plasma membrane fraction were analyzed by sds-page and phase separated in triton x-114. | 1990 | 2348834 |
| the genes encoding fructose bisphosphate aldolase in trypanosoma brucei are interspersed with unrelated genes. | the fructose bisphosphate aldolase genes of trypanosoma brucei are interspersed with unrelated genes whose transcript levels show no developmental modulation. transcription appears approximately constant across the entire locus, suggesting that aldolase mrna abundance is regulated post-transcriptionally. | 1990 | 2349093 |
| permeable trypanosome cells as a model system for transcription and trans-splicing. | we have established conditions for trypanosoma brucei permeable cells to study transcription and trans-splicing. we found that the concentration of monovalent and, to a lesser extent, divalent ions plays a critical role for the expression of a number of different genes. most remarkably, the synthesis of the spliced leader (sl) rna was optimal at 20 mm kcl, whereas higher potassium concentrations were inhibitory. in addition, mgcl2 concentrations above 3 mm led to the accumulation of a 3' end sho ... | 1990 | 2356121 |
| sequences of three vsg mrnas expressed in a mixed population of trypanosoma brucei rhodesiense. | a cdna library was constructed from a mixed population of bloodstream trypanosoma brucei rhodesiense expressing at least three different vsgs, one of which is immunologically similar to a vsg present during the metacyclic stage. complete sequence determinations of three full length vsg cdnas showed that the 5' spliced leader sequence is located 20-26 nucleotides upstream of the start codons of each of the three vsg mrnas. two of the vsgs (472 and 487 aa) are members of one c-terminal isotype gro ... | 1990 | 2357229 |
| trypanosoma brucei rhodesiense bloodstream forms: surface ricin-binding glycoproteins are localized exclusively in the flagellar pocket and the flagellar adhesion zone. | specific binding of fluoresceinated succinyl-concanavalin a, wheat germ agglutinin, and ricin to untreated and trypsinized bloodstream forms of trypanosoma brucei rhodesiense was quantitated by flow cytofluorimetry, and sites of lectin binding were identified by fluorescence microscopy. all three lectins only bound to the flagellar pocket of untreated parasites. when parasites were trypsinized to remove the variant surface glycoprotein coat, new lectin binding sites were exposed, and specific bi ... | 1990 | 2359049 |
| trypanosome ornithine decarboxylase is stable because it lacks sequences found in the carboxyl terminus of the mouse enzyme which target the latter for intracellular degradation. | ornithine decarboxylase (odc) is a key enzyme in polyamine biosynthesis. mouse odc is rapidly degraded in mouse cells, whereas odc within trypanosoma brucei, a protozoan parasite infesting cattle, is stable. we have expressed cloned odc genes of both t. brucei and mouse in odc-deficient chinese hamster ovary (cho) cells. the t. brucei enzyme is stable, whereas the mouse odc similarly expressed in cho cells is unstable. this shows that the observed difference in intracellular stability is a prope ... | 1990 | 2365702 |
| architectural organization in the interphase nucleus of the protozoan trypanosoma brucei: location of telomeres and mini-chromosomes. | we studied the spatial organization of chromatin in the interphase g1, s and g2 nucleus of the protozoan trypanosoma brucei, applying in situ hybridization with conventional fluorescence and confocal scanning optical microscopy. the majority of the trypanosome telomere gggtta repeats from different chromosomes were found clustered together, either extending in a network through the nuclear interior or localized at the nuclear periphery. the population of one hundred mini-chromosomes was often as ... | 1990 | 2369903 |
| synthesis and evaluation of 1,2,2-tris(sulfonyl)hydrazines as antineoplastic and trypanocidal agents. | several 1,2,2-tris(sulfonyl)hydrazines, conceived as prodrugs of 1,2-bis(sulfonyl)hydrazines, were synthesized and evaluated for antineoplastic and trypanocidal activities in mice. 1-methyl-1,2,2-tris(methylsulfonyl)hydrazine emerged as an extremely efficacious antitrypanosomal agent, whereas 1-(2-chloroethyl)-1,2,2-tris(methylsulfonyl)hydrazine was inactive. in contrast, 1-(2-chloroethyl)-1,2,2-tris(methylsulfonyl)hydrazine displayed potent antineoplastic activity, producing several 60-day "cur ... | 1990 | 2374151 |
| trypanocidal effect of an aqueous extract of acalypha hispida leaves. | 1990 | 2374435 | |
| isoenzymes of phosphoglycerate kinase: evolutionary conservation of the structure of this glycolytic enzyme. | 1990 | 2379683 | |
| evaluation of an arsenical compound (rm 110, mel cy, cymelarsan) against susceptible and drug-resistant trypanosoma brucei brucei and t.b. evansi. | the trypanocidal activity of an arsenical compound (rm 110; mel cy; cymelarsan) was tested in susceptible and drug-resistant stocks of t.b. brucei and t.b. evansi in vitro and in vivo. the trypanosome stocks showed different levels of susceptibility in an in vitro test, their ic50 values ranging from 3-26.9 nm. mel cy was 2.2-2.7 times more active against t.b. brucei stocks when compared to another arsenical (mel w; trimelarsan). the logarithmically transformed ic50 values for both drugs obtaine ... | 1990 | 2382101 |
| trypanocidal effects of catecholamines and indolealkylamines. | catecholamines, indolealkylamines and their analogues are oxidized at neutral or alkaline ph, producing hydrogen peroxide, quinones and free radicals. several of these amines were tested for trypanocidal effects on trypanosoma brucei, which possess a well-documented vulnerability to such oxidation products. dopamine, 5-hydroxydopamine (5-ohda), 6-hydroxydopamine (6-ohda), 5-hydroxytryptamine (5-ht), 5,6-dihydroxytryptamine (5,6-dht) and 5,7-dihydroxytryptamine (5,7-dht) killed the parasites in v ... | 1990 | 2383092 |
| characterization of an in vitro assay for import of 3-phosphoglycerate kinase into the glycosomes of trypanosoma brucei. | glycosomes are microbody organelles found in kinetoplastida, where they serve to compartmentalize the enzymes of the glycolytic pathway. in order to identify the mechanism by which these enzymes are targeted to the glycosome, we have modified the in vitro import assay developed by dovey et al. (proc. natl. acad. sci. usa 85:2598-2602, 1988). this assay measures the uptake of in vitro-translated trypanosoma brucei glycosomal 3-phosphoglycerate kinase (gpgk) by purified glycosomes. up to 50% of th ... | 1990 | 2388617 |
| the substitution of procyclic for bloodstream form trypanosoma brucei gambiense in isoenzyme studies. | examination of 10 enzymes from 8 stocks of trypanosoma brucei showed that procyclic forms could be substituted for bloodstream forms in isoenzyme studies. t. b. gambiense procyclic forms cultured in vitro offer a better source of material for genetic investigations because this species is usually of low infectivity and virulence to laboratory rodents. using 6 stocks of t. b. gambiense and 2 stocks of t. b. brucei, enzyme patterns of bloodstream and procyclic forms were identical for isocitrate d ... | 1990 | 2389316 |
| the murf3 gene of t. brucei contains multiple domains of extensive editing and is homologous to a subunit of nadh dehydrogenase. | mitochondrial murf3 transcripts of t. brucei are extensively edited by the addition and deletion of uridines. the editing creates potential initiation and termination codons and a continuous open reading frame. the predicted amino acid sequence has homology to a subunit of nadh dehydrogenase (nd7). nd7 is independently edited in two distinct domains, suggesting two editing initiation sites. editing in the two domains is differentially regulated: the 5' domain is edited in both bloodstream and pr ... | 1990 | 2393904 |
| evidence for segmental gene conversion between a cognate hsp 70 gene and the temperature-sensitively transcribed hsp70 genes of trypanosoma brucei. | the protozoan parasite trypanosoma brucei expresses several heat shock proteins of 70 kda (hsp70). we show that, from 5' to 3', a diverged cognate hsp70 gene (gene 1) is separated by about 6 kb of dna from a cluster of five identical hsp70 genes (genes 2-6). the hsp70 cognate gene has a predicted open reading frame of 676 amino-acids. the steady-state mrna levels of gene 1 are unaffected by temperature shifts up to 42 degrees c. hsps of diverse organisms share several fully conserved amino acid ... | 1990 | 2398917 |
| survival and infectivity of trypanosoma brucei in refrigerated pig blood. | trypanosoma brucei parasites survived for 72 h or longer in refrigerated pig blood. the survival period was directly proportional to the initial parasite concentration of the sample. infectivity of the parasites declined faster than survival, being less than 1 per 10(5) motile organisms at 72 h. the stage of infection in the pig (early vs. late) did not appear to influence subsequent survival periods or infectivity of the parasites in vitro. | 1990 | 2399653 |
| trypanosoma brucei: a membrane-associated protein in coated endocytotic vesicles. | membrane proteins were isolated from purified trypanosoma brucei coated endocytotic vesicles by phase separation with triton x-114. the largest abundant membrane protein was a doublet band with a molecular mass of about 77 kda. a specific antiserum was prepared against this protein by immunization with antigen bands excised from sodium dodecyl sulfate-polyacrylamide gels. immunoblot analyses with this antiserum showed that the 77-kda protein was present in other t. brucei, in t. congolense, and ... | 1990 | 2404779 |
| amplification and sequencing of genomic dna fragments encoding cysteine proteases from protozoan parasites. | cysteine protease gene fragments from three protozoan parasites trypanosoma cruzi, trypanosoma brucei, and entamoeba histolytica were amplified by the polymerase chain reaction (pcr) from genomic dna using degenerate oligonucleotide primers. the primers used for the amplification were designed based upon amino acid sequences flanking the active site cysteine and asparagine residues that are conserved in the eukaryotic cysteine proteases analyzed to date. the amplified dna fragments, representing ... | 1990 | 2406590 |
| the role of rna priming in viral and trypanosomal mrna synthesis. | 1985 | 2408758 | |
| further characterization of the extremely small mitochondrial ribosomal rnas from trypanosomes: a detailed comparison of the 9s and 12s rnas from crithidia fasciculata and trypanosoma brucei with rrnas from other organisms. | we have determined the nucleotide sequence of a maxi-circle segment from the insect trypanosome crithidia fasciculata mitochondrial dna, on which the genes for the major maxicircle transcripts of 9s and 12s are localized. the 5'-terminal sequences of these rnas were determined by wandering spot analysis. the map coordinates of the 9s and 12s rnas from trypanosoma brucei were adjusted with respect to a previous report with the aid of primer extension analysis with reverse transcriptase. this appr ... | 1985 | 2409531 |
| mature mrnas of trypanosoma brucei possess a 5' cap acquired by discontinuous rna synthesis. | mature mrnas of trypanosoma brucei have a common 5' terminal sequence of 35 nucleotides. this is acquired by an unknown mechanism from the 5' end of a separately transcribed precursor rna of about 140 nt called the mini-exon-derived rna or medrna. we have investigated the nature of the 5' ends of mature mrnas and of the medrna by chemical decapping and enzymic recapping. we infer that a 5' cap is present on both of these rnas and conclude that the mini-exon-derived rna donates its 5' cap along w ... | 1985 | 2409534 |
| apocytochrome b and other mitochondrial dna sequences are differentially expressed during the life cycle of trypanosoma brucei. | cytochromes and krebs cycle enzymes are not detected in bloodstream forms of trypanosoma brucei but are present in procyclic forms. we have analyzed transcription of mitochondrial sequences which contain the apocytochrome b gene and several other open reading frames (orfs). multiple transcripts map to individual dna sequences located on both dna strands. larger low abundance transcripts map to multiple orfs and may be precursor rnas. small abundant transcripts map to g + c rich sequences that do ... | 1985 | 2409537 |
| the biochemistry of the surface antigens of the african trypanosomes. | 1985 | 2411331 | |
| 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 |
| the trypanosome spliced leader small rna gene family: stage-specific modification of one of several similar dispersed genes. | diverse mrnas of trypanosoma brucei possess the same 5' terminal 35 nucleotides, termed the spliced leader (sl), which appears to be derived from a separate 135 nucleotide transcript. this small sl rna is encoded within a 1.4 kb unit of dna which is tandemly reiterated in the genome. in addition, there are at least 4 orphon elements containing sl sequences dispersed from the tandem array. here we show that during the trypanosome life cycle one of the sl orphons undergoes a stage-specific modific ... | 1986 | 2419837 |
| evolutionary diversity of eukaryotic small-subunit rrna genes. | the small-subunit rrna gene sequences of the flagellated protists euglena gracilis and trypanosoma brucei were determined and compared to those of other eukaryotes. a phylogenetic tree was constructed in which the earliest branching among the eukaryotes is represented by e. gracilis. the e. gracilis divergence far antedates a period of massive evolutionary radiation that gave rise to the plants, animals, fungi, and certain groups of protists such as ciliates and the acanthamoebae. the genetic di ... | 1986 | 2419907 |
| the membrane-anchoring systems of vertebrate acetylcholinesterase and variant surface glycoproteins of african trypanosomes share a common antigenic determinant. | amphiphilic detergent-soluble acetylcholinesterase (ache) from torpedo is converted to a hydrophilic form by digestion with phospholipase c from trypanosoma brucei or from bacillus cereus. this lipase digestion uncovers an immunological determinant which crossreacts with a complex carbohydrate structure present in the hydrophilic form of all variant surface glycoproteins (vsg) of t. brucei. this crossreacting determinant is also detected in human erythrocyte ache after digestion with t. brucei l ... | 1986 | 2422055 |
| diverse patterns of expression of the cytochrome c oxidase subunit i gene and unassigned reading frames 4 and 5 during the life cycle of trypanosoma brucei. | transcription of a maxicircle segment from trypanosoma brucei 164 that contains nucleotide (nt) sequences corresponding to cytochrome c oxidase subunit i (coi) and unassigned reading frames (urfs) 4 and 5 of other mitochondrial systems was investigated. two major transcripts that differ in size by ca. 200 nt map to each of the coi and urf4 genes, while a single major transcript maps to urf5. in total rna, the larger coi transcript is more abundant in procyclic forms (pfs) than in bloodstream for ... | 1985 | 2427925 |
| differential mitochondrial gene expression between slender and stumpy bloodforms of trypanosoma brucei. | bloodforms of trypanosoma brucei lack complete cytochrome and krebs cycle systems but a fully functional mitochondrial respiratory system is elaborated upon differentiation to procyclics. we previously found differential expression of some mitochondrial genes, at the level of transcript abundance, between these two life cycle stages. we report here that mitochondrial genes are also differentially expressed between the two morphological types of bloodforms. some transcripts that are more abundant ... | 1986 | 2429179 |
| monoclonal antibodies against a 60 kda phenothiazine-binding protein from trypanosoma brucei can discriminate between different trypanosome species. | the dominant structure of the cytoskeleton of the trypanosomatidae consists of a tight array of singlet pellicular microtubules, which surround the entire cell body. these microtubules are in close and stable contact with the cellular membrane. these contacts can be selectively disrupted by the action of phenothiazine drugs, which are potent trypanocides in vitro. phenothiazine-affinity chromatography of detergent solubilized proteins from trypanosoma brucei has resulted in the isolation of a pr ... | 1986 | 2430179 |
| decay-accelerating factor (daf) shares a common carbohydrate determinant with the variant surface glycoprotein (vsg) of the african trypanosoma brucei. | decay-accelerating factor (daf) is an integral membrane protein that inhibits amplification of the complement cascade on the cell surface. we and other investigators have shown that daf is part of a newly characterized family of proteins that are anchored to the cell membrane by phosphatidylinositol (pi). the group includes the variant surface glycoprotein (vsg) of african trypanosomes, the p63 protein of leishmania, acetylcholinesterase (ache), alkaline phosphatase, thy-1, 5'-nucleotidase, and ... | 1987 | 2432127 |
| two variant surface glycoproteins of trypanosoma brucei of different sequence classes have similar 6 a resolution x-ray structures. | antigenic variation in the african trypanosome is mediated through changes in the composition of the surface coat. by controlling expression of the major surface protein, the variant surface glycoprotein (vsg), from a repertoire of perhaps 1,000 different genes the organisms exhibit a series of antigenically distinct coats and evade the host's immune system. we have determined the 6 a resolution structure of a t. brucei variant surface glycoprotein, iltat 1.24, using x-ray crystallography. the c ... | 1987 | 2432433 |
| bleomycin for the cure of trypanosoma brucei brucei infections in mice: lack of pulmonary toxicity. | although bleomycin is a known pulmonary toxin, results presented herein indicate its relative safety for treatment of trypanosomiasis. more than 4 times the curative dose in this acute model of infection does not induce significant alterations of lung hydroxyproline levels, which are known to directly correlate with histopathological criteria of pulmonary fibrosis. | 1986 | 2432623 |
| trypanosoma brucei brucei, t. brucei gambiense, and t. brucei rhodesiense: common glycoproteins and glycoprotein oligosaccharide heterogeneity identified by lectin affinity blotting and endoglycosidase h treatment. | whole cell extracts of 10 clones of bloodstream forms of african trypanosomes representing two strains of trypanosoma brucei gambiense, one strain of t. b. rhodesiense and one strain of t. b. brucei were fractionated on sodium dodecyl sulfate-polyacrylamide gels, electrophoretically transferred to nitrocellulose paper, and probed with horseradish peroxidase conjugated lectins to detect glycoproteins. variant specific glycoproteins of all 10 clones bound peroxidase labeled concanavalin a, but per ... | 1987 | 2433150 |
| trypanosoma brucei rhodesiense infection in mice prevents virus-induced diabetes: possible role of interferon and immunological mechanisms. | b10.br, dba/2, and balb/c by j mice were infected with trypanosoma brucei rhodesiense (lou tat clone 1). subsequent infection with the d variant of encephalomyocarditis virus (emc-d) resulted in no diabetes or encephalitis, even in the susceptible dba/2 and balb/c by j strains. low levels of circulating interferon (ifn) were detected in trypanosome-infected mice at the time of emc-d infection. all strains were severely immunosuppressed as a result of trypanosome infection, as evidenced by decrea ... | 1986 | 2433362 |
| rna turnover in trypanosoma brucei. | regulation of variant surface glycoprotein (vsg) mrna turnover in trypanosoma brucei was studied in bloodstream forms, in procyclic cells, and during in vitro transformation of bloodstream forms to procyclic cells by approach-to-equilibrium labeling and pulse-chase experiments. upon initiation of transformation at 27 degrees c in the presence of citrate-cis-aconitate, the half-life of vsg mrna was reduced from 4.5 h in bloodstream forms to 1.2 h in transforming cells. concomitantly, an approxima ... | 1987 | 2436040 |
| variation of g-rich mitochondrial transcripts among stocks of trypanosoma brucei. | we have compared maxicircle transcripts from eight stocks of subspecies of trypanosoma brucei. transcripts from the rrna and protein genes have a constant size among stocks and exhibit only minor variation in abundance. in contrast, four of the g+c rich sequences encode multiple transcripts that very markedly in size or abundance. maxicircle nucleotide sequence comparison of three stocks shows very limited sequence divergence suggesting that sequence divergence may not explain the transcript var ... | 1987 | 2437452 |
| rna end-labeling and rna ligase activities can produce a circular rrna in whole cell extracts from trypanosomes. | we have found two enzymatic activities in whole cell extracts from trypanosoma brucei; an end-labeling reaction involving a single uridine at the 3' end of ribosomal rnas (rrnas) and an rna ligase activity joining 5' monophosphates to 3' hydroxyl groups. the rna ligase acts upon one of the small rrnas (180 nucleotides) from the trypanosome ribosomal repeat unit, forming a circular rna. the specific circularization of this small rrna is probably dependent on the secondary structure of the molecul ... | 1987 | 2437529 |
| transcription of kinetoplast dna minicircles. | the mitochondrial dna of trypanosomes is organized as a network of catenated circular dna molecules called the kinetoplast. the minicircles of the kinetoplast are 1 kb circular dna molecules present at 5,000-10,000 copies per network. the maxicircles are 20 kb circular molecules present at 50-100 copies per network. maxicircles are transcribed and are thus analogous to mitochondrial dnas. here we show that, contrary to previous reports, the minicircles of t. brucei are also transcribed. a minici ... | 1987 | 2438049 |
| [experimental trypanosomiasis caused by trypanosoma brucei brucei in domestic cattle. antigenic diversity and trypanotolerance]. | the antigenic repertoire expressed in four trypanosensitive zebu cattle after cyclic infection by a late variant of the repertoire ditar 1 was studied using agglutinating antibodies. the repertoire expressed appeared similar to that found previously following syringe infection or cyclic infection by an early variant in trypanosensitive and trypanoresistant bovids. the late variant used to infect the glossina, however, appeared earlier, immediately after the dominant variants. these results also ... | 1987 | 2438916 |
| analysis of protective epitopes on the variant surface glycoprotein of a trypanosoma brucei brucei (ditat 1.3.) using monoclonal antibodies. | 1987 | 2439974 | |
| vsg gene 118 is transcribed from a cotransposed pol i-like promoter. | to understand the control of differential variant cell surface glycoprotein (vsg) gene expression in t. brucei, we studied vsg gene and expression site transcription regulation. we show that the interchromosomal duplicative transposition of vsg gene 118, on an unusually large transposed segment, results in the transcriptional activation of a cotransposed rna polymerase i-like (pol i) promoter, from which the vsg gene is transcribed. transcription of vsg genes by pol i can therefore be regulated ... | 1987 | 2440585 |
| trypanosoma brucei brucei and trypanosoma brucei gambiense: stage specific differences in wheat germ agglutinin binding and in endoglycosidase h sensitivity of glycoprotein oligosaccharides. | gel electrophoresis, lectin affinity blotting, and endoglycosidase h digestion have been used to analyze the glycoprotein profiles of bloodstream and procyclic forms of trypanosoma brucei brucei and t. b. gambiense. proteins resolved by polyacrylamide gel electrophoresis were stained with silver nitrate or electrophoretically transferred to nitrocellulose and probed with a horseradish peroxidase conjugate of either concanavalin a or wheat germ agglutinin. silver staining showed, as expected, tha ... | 1987 | 2440711 |
| ms and nmr analysis of the cross-reacting determinant glycan from trypanosoma brucei brucei mitat 1.6 variant specific glycoprotein. | the cross-reacting determinant glycan from trypanosoma brucei brucei mitat 1.6 is known to contain galactose, mannose and non-acetylated glucosamine. the structural elucidation of this oligosaccharide has been impeded by an unusual non-glycosidic linkage to the peptide chain and a glycosidic linkage to inositol phosphate on either side of the oligosaccharide. using two different approaches for the isolation of the glycan, namely hydrolysis to give the oligosaccharide directly or pronase digestio ... | 1987 | 2441699 |
| studies on the efficacy of dl-alpha-difluoromethylornithine (dfmo) associated with bleomycin and suramin for treatment of mice infected with metacyclic forms of trypanosoma brucei brucei. | nmri mice were treated with dfmo-bleomycin and dfmo-suramin drug combinations at day 8 post-inoculation. the highest percentage of parasitologically non patent mice were attained with dfmo-suramin combination treatments. parasitological and serological examinations of the non-relapsing mice strongly suggests trypanosome clearance. | 1987 | 2442883 |
| structural features of antigenic determinants on variant surface glycoproteins from trypanosoma brucei. | the immunochemical structure of two variant surface glycoproteins (vsgs) from trypanosoma brucei has been studied using monoclonal and polyclonal antibodies. these two vsgs, watat 1.1 and watat 1.12 have been shown to possess cross-reactive surface-exposed antigenic determinants [barbet et al., nature 300, 53-57 (1982)] and similar n-terminal amino acid sequences [olafson et al., molec. biochem. parasit. 12, 287-298 (1984)]. monoclonal and polyclonal antibodies were raised against the soluble fo ... | 1987 | 2443842 |
| the anatomy and transcription of a telomeric expression site for variant-specific surface antigens in t. brucei. | the variant specific surface glycoprotein (vsg) genes of t. brucei are expressed in telomeric expression sites. we have determined the structure of the active site in trypanosome variant 221a, which contains vsg gene 221, by analysis of cloned dna segments that represent 65 kb of the 5'-flanking region of the vsg gene. in nuclear run-on experiments, 57 kb of adjacent sequences are cotranscribed with the vsg gene at approximately similar rates and in the alpha-amanitin-resistant manner characteri ... | 1987 | 2444341 |
| line-1: a mammalian transposable element. | 1987 | 2445384 | |
| dna-binding fingers encoded by a trypanosome retroposon. | a trypanosoma brucei repeated dna element (trs-1, for trypanosome repeated sequence), which seems transposable, may encode a 1651 amino acid polypeptide showing homology with reverse transcriptase. this polypeptide would also carry a dna-binding domain, as suggested by the presence of five dna-binding "fingers" homologous to those of the transcription factor tfiiia of xenopus laevis and retroviral dna-binding proteins. | 1987 | 2445994 |
| detection of circulating trypanosomal antigens by double antibody elisa using antibodies to procyclic trypanosomes. | a double antibody sandwich elisa technique has been developed for detection of antigens of african trypanosomes present in the sera of infected mammals. the assay uses a high titre, high affinity rabbit antiserum made to purified membranes of procyclic trypanosomes as "capture" reagent and a mixture of three biotin-labelled trypanosome-specific monoclonal antibodies as detecting reagent. the monoclonal antibodies were chosen on the basis of their specificity for surface membrane antigens of tryp ... | 1987 | 2447550 |
| direct analysis of the mini-exon donor rna of trypanosoma brucei: detection of a novel cap structure also present in messenger rna. | the mini-exon, a short segment found at the 5' end of trypanosome mrnas, is contributed by a small rna, the mini-exon donor (medrna). in vivo 32p-labeled medrna, a set of smaller rnas related to it, and mrna, were purified from trypanosoma brucei by hybrid selection and gel electrophoresis. using rna fingerprinting and sequencing techniques, mini-exon oligonucleotides were identified and characterized. we detected a novel 5' terminal capped oligonucleotide present in both medrna and mrna. this s ... | 1987 | 2447560 |
| intracellular colocalization of variant surface glycoprotein and transferrin-gold in trypanosoma brucei. | endocytosis and intracellular transport has been studied in the bloodstream forms of trypanosoma brucei by light and electron microscopy, using colloidal gold coupled to bovine transferrin (transferrin-gold). the endocytosed transferrin-gold, visualized by silver intensification for light microscopy, was present in vesicular structures between the cell nucleus and flagellar pocket of the organism. at the ultrastructural level, transferrin-gold was present after a 10-min incubation in the flagell ... | 1988 | 2448312 |
| creation of aug initiation codons by addition of uridines within cytochrome b transcripts of kinetoplastids. | the cytochrome b gene of trypanosoma brucei has an atg codon near its 5' end but the cytochrome b genes of the related kinetoplastids leishmania tarentolae and crithidia fasciculata lack an atg. recent results have shown that 34 uridines that are not encoded in the genome are added within the 5' end of t. brucei cytochrome b transcripts during or after transcription. these additions create an aug in the transcript that is 20 amino acids upstream of the aug predicted from the genomic sequence. we ... | 1988 | 2448777 |
| partial characterization of the cross-reacting determinant, a carbohydrate epitope shared by decay accelerating factor and the variant surface glycoprotein of the african trypanosoma brucei. | the variant surface glycoprotein (vsg) of the african trypanosome is anchored in the cell membrane by a complex glycan attached to phosphatidylinositol. the carboxyl terminal portion of vsg contains a cryptic carbohydrate epitope, the cross-reacting determinant (crd), that is revealed only after removal of the diacylglycerol by phosphatidylinositol-specific phospholipase c (piplc) or vsg lipase. recently, we have shown that after hydrolysis by piplc, decay-accelerating factor (daf)--a mammalian ... | 1988 | 2450138 |
| physical studies of trypanosoma brucei variant surface glycoproteins and their antigenic determinants. | secondary structure determinations have been carried out on two antigenically related variant surface glycoproteins (vsg's) from trypanosoma brucei, watat 1.1 and watat 1.12. the two molecules, which bear highly homologous amino-terminal sequences, showed subtle differences in their circular dichroism (cd). computer analysis revealed that the contribution of alpha helix to the secondary structure of the vsg's was 49% for watat 1.1 and 52% for watat 1.12. unfolding studies using guanidine hydroch ... | 1988 | 2450568 |
| subcellular sequestration of an antigenically unique beta-tubulin. | tubulin from trypanosoma brucei was characterized by western blotting using well defined monoclonal antibodies reacting with alpha- or beta-tubulin and a new monoclonal antibody, 1b41, raised against a microtubule-enriched fraction of t. brucei, which specifically reacts with the beta-subunit of tubulin from either t. brucei or rat brain. this antibody has been used to examine the subcellular distribution of the corresponding antigen in t. brucei by indirect immunofluorescence. the epitope recog ... | 1988 | 2452022 |
| topologic analysis of the epitopes of a variant surface glycoprotein of trypanosoma brucei. | a panel of variant-specific mab has been raised against the trypanosoma brucei variant mitat 1.2. the binding characteristics of these mab have been determined by a combination of immunofluorescence assays, using living or fixed trypanosomes, and solid phase assays, using purified variant surface glycoprotein. in addition, these mab have been tested for their ability to neutralize mitat 1.2 infections in mice. finally, the epitopes recognized by the mab have been defined by competitive binding a ... | 1988 | 2452200 |
| extensive editing of the cytochrome c oxidase iii transcript in trypanosoma brucei. | the gene for cytochrome oxidase subunit iii (coiii) is not detected in t. brucei by nucleotide sequence analysis or by cross-hybridization studies. we have identified the coiii transcript in the t. brucei mitochondrion by rna and cdna sequencing. its nucleotide and predicted amino acid sequences are very similar to those from the coiii genes in related species. a mitochondrial dna sequence that matches the coiii transcript, except for the absence of numerous thymidines, is located upstream of th ... | 1988 | 2452697 |
| developmental aspects of uridine addition within mitochondrial transcripts of trypanosoma brucei. | the mitochondrial respiratory system is absent in slender bloodstream forms of trypanosoma brucei, incomplete in stumpy bloodstream forms, and complete in procyclic (insect) forms. the steady-state abundance of transcripts of some mitochondrially encoded components of the respiratory system correlates with its differential expression in different life cycle stages. recently, it was reported that uridines which are not encoded in the genome are added to cytochrome b and cytochrome oxidase ii tran ... | 1988 | 2452974 |
| further characterization of the membrane anchor found on the tissue-specific class i molecule qa2. | previous studies have determined that various qa2 serologic determinants can be removed from the surface of spleen cells by treatment with a phospholipase c. our studies have determined that the class i molecule qa2, expressed on the surface of spleen cells and activated t cells, behaves as an integral membrane protein based on its ability to associate with detergent micelles. studies utilizing two purified phospholipase c have revealed that although most (90 to 95%) of the qa2 molecules express ... | 1988 | 2453559 |
| independent regulation of b cell responses to surface and subsurface epitopes of african trypanosome variable surface glycoproteins. | regulation of b cell responses to the trypanosome surface ag was examined in h-2k compatible "responder" b10.br and "nonresponder" c3h mice after infection with two variant clones of trypanosoma brucei rhodesiense. development of a selective ria for independent detection of antibody binding to surface (exposed) and subsurface (buried) epitopes of the trypanosome variable surface glycoprotein (vsg) molecule permitted sensitive quantitation and kinetic characterization of immune responses to these ... | 1988 | 2454998 |
| cloning and transcriptional analysis of a variant surface glycoprotein gene expression site in trypanosoma brucei. | the variant surface glycoprotein (vsg) gene expression site in trypanosoma brucei variant 117a has been mapped to a point about 40 kb upstream from the vsg gene. sequences upstream from the previously identified [cully, d.f. et al. (1985) cell 42, 173-182] expression site associated gene (esag-i) have been cloned and a stable 1.3 kb transcript has been localized immediately 5' to esag-i. this transcript is in the same orientation and approximately as abundant as the esag-i message. a highly cons ... | 1988 | 2455225 |
| variant specific transcripts from the co-transposed segments of variant surface glycoprotein genes in trypanosoma brucei. | we examined steady-state transcripts from the sequences immediately upstream of the 1 and 11 variant surface glycoprotein (vsg) genes in trypanosoma brucei of the istar 1 serodeme. these sequences, the co-transposed segment, differ in size and sequence, and produce a variety of variant-specific polyadenylated transcripts. most, if not all, of these transcripts, some of which may be precursors, contain the spliced leader (sl). variant specific transcription extends from 5' of the co-transposed se ... | 1988 | 2455228 |
| trypanosoma brucei sspp.: cleavage of variant specific and common glycoproteins during exposure of live cells to trypsin. | intact bloodstream forms of trypanosoma brucei brucei, t.b. gambiense, and t.b. rhodesiense and procyclic forms of t.b. brucei and t.b. gambiense were incubated in trypsin, solubilized for gel electrophoresis, and analyzed for removal of surface molecules. silver-stained gels and transfer blots probed with horseradish peroxidase-conjugated or radiolabeled lectins revealed that only three glycoproteins, gp120p, gp91p, and gp23p, were removed from the surface of procyclic forms by trypsin. the var ... | 1988 | 2456221 |
| rna editing. in search of a template. | 1988 | 2457168 | |
| use of dark ground microscopy in haematology. | the novel combination of vital staining, quick drying of thin films, and dark ground microscopy furnishes new information about organelles, granules, and precipitates in blood cells. the preparations are permanent and give optical signals of high contrast which depend on refraction or dichroism of the object. mitochondria are readily shown and can be counted and sized. pilot observations suggest that mitochondria in red cells may give information about cell maturity and splenic function; that th ... | 1988 | 2457605 |
| glycophosphatidylinositol-anchored proteins in metacyclic trypomastigotes of trypanosoma cruzi. | we searched for the presence of glycophosphatidylinositol (gpi)-anchored proteins in epimastigotes and metacyclic trypomastigotes of trypanosoma cruzi, by treatment of parasite lysates with the gpi-specific phospholipase c of trypanosoma brucei. upon treatment, several proteins (70-90 kda) in metacyclics, but none in epimastigotes, reacted with antibodies to the cross-reacting determinant (crd), an epitope revealed on the variant surface glycoproteins of t. brucei following removal of the diacyl ... | 1988 | 2457804 |
| post-transcriptional control of the differential expression of phosphoglycerate kinase genes in trypanosoma brucei. | the genes for the cytosolic and glycosomal phosphoglycerate kinases (pgk) of trypanosoma brucei are found in a compact tandem array together with a third pgk-related gene, expressed at low level. expression of the two pgk genes is differentially regulated in the life cycle of t. brucei: the glycosomal pgk and its mrna are abundant in the mammalian stage of the cycle but not in the insect stage, whereas the reverse is found for the cytosolic pgk and its mrna. nevertheless, our experiments indicat ... | 1988 | 2458474 |
| characterization of the cross-reacting determinant (crd) of the glycosyl-phosphatidylinositol membrane anchor of trypanosoma brucei variant surface glycoprotein. | the cross-reacting determinant (crd epitope) of the glycosyl-phosphatidylinositol (gpi) membrane anchor of trypanosoma brucei variant surface glycoprotein has been analysed by selective chemical and enzymic modification of the isolated gpi structure combined with the use of a competitive elisa inhibition assay for the detection of crd epitopes. the data show that the crd consists of at least three overlapping epitopes involving different regions of the molecule including the inositol 1,2-cyclic ... | 1988 | 2458923 |
| a 5' exo-ribonuclease and rna ligase of t. brucei. | we identified a mg2+ dependent 5' exo-ribonuclease and an rna ligase in cell-free extracts of trypanosome brucei. the exo-ribonuclease in s100 or nuclear extracts, removes about 20 nts from the 5' end of sp6 derived capped as well as uncapped rna and then stops. in contrast to the activity of the exo-ribonuclease on capped sp6 mini-exon transcripts, the exonuclease cannot degrade trypanosome-derived mini-exon transcripts or the mini-exon located at hsp 70 mrnas. we therefore assume that the four ... | 1988 | 2460826 |
| screening compounds for sleeping sickness therapy without relapse. | the finding of an intracellular stage of trypanosoma brucei in ependymal cells of the choroid plexus (abolarin et al., 1986) and of the lining of the ventricles (ormerod and hussein, 1986) has suggested a new technique for screening trypanocidal compounds against the failure of drugs to eliminate "occult" stages of the infection (raseroka and ormerod, 1986). a (donor) mouse, infected for 28 days, is dosed with a drug, or combination of drugs, and samples of blood, cerebral cortex, choroid plexus ... | 1988 | 2461813 |
| procyclin: an unusual immunodominant glycoprotein surface antigen from the procyclic stage of african trypanosomes. | an immunodominant species-specific surface glycoprotein antigen was purified from procyclic culture forms of trypanosoma brucei rhodesiense using lectin affinity chromatography and a monoclonal antibody immunoadsorbent. the purified molecule appears on a 10% polyacrylamide gel as a wide, dark silver staining band having an apparent molecular mass of between 30 and 40 kda, identical to that revealed by immunoblotting using anti-procyclic lysates. the molecule, which we have named procyclin, was s ... | 1988 | 2464763 |
| phylogenetic evidence for tertiary interactions in 16s-like ribosomal rna. | major efforts are underway to elucidate the spatial distribution of ribosomal rnas (rrnas) in the ribosome. an especially informative approach is the identification of likely base-base tertiary interactions within the rna by phylogenetic comparison. herein evidence is presented for three heretofore unrecognized candidate tertiary interactions, g506/c525, c779/g803 and a994/u1380 (1) in 16s-like rrnas. this brings to eight the number of such interactions that are strongly supported by phylogeneti ... | 1989 | 2468130 |
| mapping of segmental antigenic determinants on structurally related variant surface glycoproteins of trypanosoma brucei. | to study common and variant specific antigenic determinants on variant surface glycoproteins from trypanosoma brucei, we have selected four serologically cross-reacting variant populations. monoclonal antibodies were raised against the purified variant surface glycoproteins from each variant trypanosome population. six monoclonal antibodies bind to segmental epitopes and one binds to a topographically assembled epitope. amino acid compositions of these variant surface glycoproteins reveal striki ... | 1988 | 2468352 |
| two variant surface glycoprotein genes distinguish between different substrains of trypanosoma brucei gambiense. | trypanosoma brucei gambiense differs from other t. brucei subspecies in the stability and conservation of its bloodstream form antigenic repertoire. two variant surface glycoprotein (vsg) cdna clones corresponding to the antigens u1 and l2 were isolated from t. b. gambiense bacteriophage lambda gt11 expression libraries and characterized. a third vsg cdna clone, p1, was also examined. the l2 and u1 vsg genes are present in a large number of t. b. gambiense stocks isolated over a thirty-year peri ... | 1989 | 2469013 |
| life-cycle-stage- and stock-specific labelling by monoclonal antibodies of trypanosoma brucei procyclic forms. | 1989 | 2471186 | |
| 24 hour polysomnographic evaluation in a patient with sleeping sickness. | a 24 h polysomnographic recording was performed in a patient with sleeping sickness presenting an atypical neurological syndrome. trypanosoma gambiense was found in a lymph gland puncture and the csf, and a serologic immunofluorescence test was positive. the scoring technique of the polygraphic traces had to be adapted because of the presence of a permanent eeg delta wave activity during the nrem sleep stages, and the method used by schwartz and escande (1970) was applied. rem sleep and wakefuln ... | 1989 | 2471615 |
| a silent open reading frame of trypanosoma brucei coding for a protein which shares epitopes with the major structural protein of the paraflagellar rod. | 1989 | 2474796 | |
| the procyclic acidic repetitive proteins of trypanosoma brucei. purification and post-translational modification. | the procyclic acidic repetitive protein (parp) of trypanosoma brucei was purified by cell fractionation followed by ion-exchange and concanavalin a-sepharose affinity chromatography. parp is membrane-bound and comprises about 1% of the total procyclic trypanosome protein or 6 x 10(6) molecules per parasite. the results of nh2-terminal sequencing and amino acid analysis indicate that parp is processed by removal of an n-terminal signal sequence and the hydrophobic cooh terminus. metabolic labelin ... | 1989 | 2475493 |
| analysis of propionibacterium acnes-induced non-specific immunity to trypanosoma brucei in mice. | mice treated with dead propionibacterium acnes (previously called corynebacterium parvum), up to 30 days before infection with any of three strains of trypanosoma brucei, were more able to limit the level of first-wave parasitaemia than untreated controls. reduced parasitaemia was not due to enhanced phagocytosis of input parasites and was associated with a dramatic reduction in the proportion of multiplying t. brucei in the blood of treated as compared to control mice. for 4 days after p. acnes ... | 1989 | 2476711 |
| mapping of branch sites in trans-spliced pre-mrnas of trypanosoma brucei. | the process of trans splicing is essential to the maturation of all mrnas in the trypanosomatidae, a family of protozoan parasites, and to specific mrnas in several species of nematode. in trypanosoma brucei, a 39-nucleotide (nt) leader sequence originating from a small, 139-nt donor rna (the spliced leader [sl] rna) is spliced to the 5' end of mrnas. an intermediate in this trans-splicing process is a y structure which contains the 3' 100 nt of the sl rna covalently linked to the pre-mrna via a ... | 1989 | 2479824 |