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T Seebeck

Publications and source records attributed to T Seebeck.

At least 37 records · Page 2Linked to original sources
PubMed1996

Trypanosome variant surface glycoproteins are recognized by self-reactive antibodies in uninfected hosts.

The variant surface glycoproteins (VSGs) of African trypanosomes form a dense surface coat on the bloodstream parasites. VSGs are immunodominant antigens that stimulate a rapid antibody response in trypanosome-infected individuals. In the present study, we examined VSG-specific antibodies present not only in sera from infected individuals but also in sera from individuals that had never been exposed to trypanosomes. Native antibodies against different VSGs were detected in sera from uninfected mice, bovines, and humans; the antibodies were revealed to be exclusively directed against variable determinants of the antigens. Further experimentation demonstrated that such native antibodies immunoreact with cellular components of mice and thus are most likely produced by the self-reactive B-cell compartment of the murine immune system.

Animals↗
PubMed1995

MHC-dependent mate preferences in humans.

One substantial benefit of sexual reproduction could be that it allows animals (including humans) to react rapidly to a continuously changing environmental selection pressure such as coevolving parasites. This counteraction would be most efficient if the females were able to provide their progeny with certain allele combinations for loci which may be crucial in the parasite-host arms race, for example the MHC (major histocompatibility complex). Here we show that the MHC influences both body odours and body odour preferences in humans, and that the women's preferences depend on their hormonal status. Female and male students were typed for their HLA-A, -B and -DR. Each male student wore a T-shirt for two consecutive nights. The next day, each female student was asked to rate the odours of six T-shirts. They scored male body odours as more pleasant when they differed from the men in their MHC than when they were more similar. This difference in odour assessment was reversed when the women rating the odours were taking oral contraceptives. Furthermore, the odours of MHC-dissimilar men remind the test women more often of their own actual or former mates than do the odours of MHC-similar men. This suggests that the MHC or linked genes influence human mate choice today.

Adult↗
PubMed1995

Repetitive proteins from the flagellar cytoskeleton of African trypanosomes are diagnostically useful antigens.

Trypanosome infection of mammalian hosts leads, within days, to a strong early response against a small, distinct number of parasite proteins. One of these proteins is the variable surface glycoprotein (VSG). Most of the others are apparently non-variable, intracellular trypanosome proteins. Two of these antigens I2 and I17 are now characterized at the molecular level. Both exhibit a highly repetitive amino acid sequence organization, but they show no sequence similarity either to each other or to any other proteins known to date. Preliminary serological analyses indicate that both allow the early, sensitive and specific detection of infections with different species of trypanosomatids, making them interesting candidates for the development of diagnostic tools for trypanosomiasis detection.

Amino Acid Sequence↗
PubMed1994

The major components of the paraflagellar rod of Trypanosoma brucei are two similar, but distinct proteins which are encoded by two different gene loci.

The flagellum of trypanosomatids contains two major structural elements, the microtubular axoneme, which is the mechanochemical motor of the cell, and the paraflagellar rod (PFR), a highly organized, three-dimensional fiber network of unknown function. Its occurrence is limited to a few groups of unicellular eukaryotes, the Euglenoids, Dinoflagellates, and Kinetoplastids. The PFR of trypanosomes consists of two similar proteins of approximate molecular masses of 69 and 73 kDa. This laboratory and others have earlier characterized the genes coding for the 69-kDa PFR species in Trypanosoma brucei and Trypanosoma cruzi. The present study reports the characterization of the genes coding for the 73-kDa PFR protein from T. brucei. Their gene product, PFR-C, is closely related to, but clearly distinct from, the 69 kDa species PFR-A. This finding indicates that the PFR fibers of the flagellum might represent heteropolymers formed by PFR-A and PFR-C, akin to the situation seen in microtubules or intermediate filaments. PFR-A and PFR-C are each coded for by a similarly organized cluster of four closely spaced, tandemly arranged genes. The 5'-untranslated region of the first gene in each cluster is different from those of the following three genes, which are identical among each other. Conversely, the 3'-untranslated regions of the first three genes of each cluster are identical, while the corresponding region of the fourth gene is different. This unusual organization leads to the generation of mRNAs which contain identical coding sequences but different 5'- and 3'-noncoding regions.

Amino Acid Sequence↗
PubMed1993

A repetitive protein from Trypanosoma brucei which caps the microtubules at the posterior end of the cytoskeleton.

The major structural component of the cyto-architecture of Trypanosoma brucei is a microtubular array which envelopes the entire cell body and which is in close contact with the overlying cell membrane. A cytoskeletal protein has been identified which is associated with the microtubules of this array at their posterior ends exclusively. This protein, Gb4, is coded for by a very large gene which consists of numerous, tandemly linked repeat units of 0.6 kb length. Despite the large size of the gene, and also of the corresponding mRNA, the mature Gb4 protein has a size of only 28 kDa. Gb4 is well conserved between different species of African trypanosomes.

Amino Acid Sequence↗
PubMed1993

Cytoskeleton-associated antigens from African trypanosomes are recognized by self-reactive antibodies of uninfected mice.

Serum from uninfected mice of different strains, as well as from germ-free animals, contains antibodies which react specifically with at least two trypanosomal proteins, I/6 and MARP1. These antibody populations are highly specific for the respective proteins, are of similar affinity as hyperimmune antibodies, and consist of IgM as well as IgG isotypes. Hyperimmune antibody raised against the cross-reacting trypanosomal protein I/6 detects a 60 kDa protein in mouse 3T6 cells, which is a component of the fibroblast cytoskeleton.

Animals↗
PubMed1992

Identification and characterization of two repetitive non-variable antigens from African trypanosomes which are recognized early during infection.

The present paper describes two repetitive proteins representing common antigens of African trypanosomes which are non-variant and which are recognized early in infection by the host immune system. These antigens were identified by their ability to immunoreact with bovine serum taken during the early phase of a cyclic trypanosomal infection. Screening of a cDNA library from T. b. gambiense with such early infection serum identified a protein which contains a repetitive motif consisting of 68 amino acid repeat units (GM6). Immunofluorescence and immunogold electron microscopy revealed that GM6 is located on fibres which connect the microtubules of the membrane skeleton with the flagellum. A second repetitive antigen detected by this serum is MARP1 (microtubule-associated repetitive protein 1), a protein previously characterized in this laboratory as a high-molecular weight component of the membrane skeleton, which consists of more than 50 tandemly repeated, near-identical 38 amino acid repeat units. Beta-galactosidase fusion products of both proteins demonstrated a strong immunoreactivity with sera from T. b. brucei and T. congolense-infected cattle. The result from this preliminary immunological evaluation indicates a high immunodiagnostic sensitivity (90%) of the two recombinant antigens which make them interesting candidates for immunodiagnosis of trypanosomiasis in cattle.

Amino Acid Sequence↗
PubMed1992

A novel microtubule-binding motif identified in a high molecular weight microtubule-associated protein from Trypanosoma brucei.

The major component of the cytoskeleton of the parasitic hemoflagellate Trypanosoma brucei is a membrane skeleton which consists of a single layer of tightly spaced microtubules. This array encloses the entire cell body, and it is apposed to, and connected with, the overlying cell membrane. The microtubules of this array contain numerous microtubule-associated proteins. Prominent among those is a family of high molecular weight, repetitive proteins which consist to a large extent of tandemly arranged 38-amino acid repeat units. The binding of one of these proteins, MARP-1, to microtubules has now been characterized in vitro and in vivo. MARP-1 binds to microtubules via tubulin domains other than the COOH-termini used by microtubule-associated proteins from mammalian brain, e.g., MAP2 or Tau. In vitro binding assays using recombinant protein, as well as transfection of mammalian cell lines, have established that the repetitive 38-amino acid repeat units represent a novel microtubule-binding motif. This motif is very similar in length to those of the mammalian microtubule-associated proteins Tau, MAP2, and MAP-U, but both its sequence and charge are different. The observation that the microtubule-binding motifs both of the neural and the trypanosomal proteins are of similar length may reflect the fact that both mediate binding to the same repetitive surface, the microtubule, while their sequence and charge differences are in agreement with the observation that they interact with different domains of the tubulins.

Alkaloids↗
PubMed1991

The Trypanosoma brucei cytoskeleton: ultrastructure and localization of microtubule-associated and spectrin-like proteins using quick-freeze, deep-etch, immunogold electron microscopy.

We have used a combination of quick-freezing/deep-etching and colloidal gold immunocytochemistry (i) to analyze the molecular organization of the microtubular membrane skeleton and the flagellum of Trypanosoma brucei, and (ii) to localize two defined cytoskeletal proteins within these structures. The cell body of trypanosomatids is enveloped by a membrane skeleton consisting of a tightly packed array of microtubules which are closely associated with the cell membrane. The membrane-oriented face of these microtubules is richly decorated with microtubule-associated proteins, which form intermicrotubule and microtubule-membrane linkers. In contrast, the cytoplasmic faces of the microtubules have a smooth, nondecorated appearance. A previously identified, highly repetitive microtubule-associated protein is confined to the membrane-oriented face of the microtubular array, suggesting that the function of this protein may be that of a microtubule-membrane linker. Quick-freezing has also been used to reveal the geometric organization of the paraflagellar rod structure in the flagellum, its interaction wit the cell body, and a unique series of fleur-de-lis-like molecules which link this organelle to axonemal microtubules. Immunohistochemistry using an antibody against human erythrocyte spectrin suggests that these linker structures may contain ancestral spectrin-like molecules.

Animals↗
PubMed1991

The cytoskeletal architecture of Trypanosoma brucei.

The cytoskeleton of Trypanosoma brucei has been analyzed by the high-resolution technique of quick-freeze deep-etch rotary-shadowing electron microscopy. The study provides detailed structural information on the subpellicular array of microtubules, the flagellum, and the interaction of these 2 major structures of the trypanosomal cytoskeleton with each other. The subpellicular microtubules closely interact both with the cell membrane and with each other. At the anterior tip of the cell they converge into a tightly closed structure, whereas at the posterior end the microtubular array remains open ended. The microtubular array is involved also in forming the opening of the flagellar pocket. The microtubular array interacts with the paraflagellar rod of the flagellum through a dense meshwork of fibers that are anchored on the microtubular surface with one end and within the paraflagellar rod structure with the other. The highly ordered, 3-dimensional network of the paraflagellar rod itself is connected tightly to the microtubular axoneme of the flagellum through a regular array of fleur-de-lis-shaped linking structures.

Animals↗
PubMed1990

Echinococcus multilocularis: characterization of a DNA probe.

A 0.6 kb DNA fragment has been isolated from a genomic sublibrary of the cestode Echinococcus multilocularis. This DNA-fragment showed a strong hybridization signal to 32PdCTP labeled total DNA prepared from E. multilocularis metacestode material. The fragment was subcloned into the Escherichia coli vector Bluescript BS+ resulting in the recombinant plasmid pAL1. The recombinant parasite DNA probe was labeled by biotinylation and hybridized to Southern blots of resolved EcoRI/PstI digested genomic DNA originating from E. multilocularis, E. granulosus and other helminth species (Taenia hydatigena, T. crassiceps, T. saginata, Mesocestoides corti, Hymenolepis diminuta, Moniezia expansa). The Southern blot hybridization experiments revealed that the DNA probe pAL1 was specific for E. multilocularis and E. granulosus. By comparison of the hybridization banding patterns a clear discrimination between E. multilocularis and E. granulosus was possible at the genome level. Furthermore, pAL1 was used to detect genetic variation within a set of different E. multilocularis isolates which had been experimentally maintained in mice by parasite tissue transplantation.

Animals↗
PubMed1990

Humoral and cellular immune response in mice and dogs induced by a recombinant Echinococcus multilocularis antigen produced by a Salmonella typhimurium vaccine strain.

A gene fragment (II/3-10) from the cestode Echinococcus multilocularis coding for a species-specific antigen was expressed in the live attenuated Salmonella typhimurium vaccine strain LT2 M1C. The recombinant vaccine (S. typhimurium + pVM II/3-10) was assessed for its potential to induce both a humoral and cell-mediated immune response in mice and dogs. Both subcutaneous and peroral administration of the vaccine resulted in antibody synthesis and lymphocyte priming of C57BL/6J mice against S. typhimurium antigens as well as against the recombinant E. multilocularis antigen. Two vaccinated (subcutaneous and peroral) dogs showed a strong humoral immune response to S. typhimurium antigens and to the recombinant E. multilocularis antigen, but proliferation of peripheral blood lymphocytes was not detectable against the bacterial S. typhimurium antigens. Regarding the recombinant E. multilocularis antigen, borderline lymphocyte proliferation was demonstrated following subcutaneous and none following peroral administration of the recombinant vaccine to dogs.

Animals↗
PubMed1989

A glycosomal protein (p60) which is predominantly expressed in procyclic Trypanosoma brucei. Characterization and DNA sequence.

Glycosomes are specialized organelles of trypanosomes which contain glycolytic enzymes as their major protein components in Trypanosoma brucei bloodstream form. In the glycosomes of the insect form of T. brucei, additional enzyme activities are found but have not yet been ascribed to a particular protein molecule. In this study, we report the characterization of a 60-kDa glycosomal protein (p60) encoded by a single copy gene which is transcribed into a mRNA of 2.9 kilobases. The gene codes for a protein of 472 amino acids with a molecular mass of 52.5 kDa, suggesting that the mRNA contains large untranslated regions of about 1.4 kilobases. Genomic DNA hybridizations have shown that the gene for p60 is confined to the family of Trypanosomatidae. Sequence comparison confirmed that p60 is not a member of a conserved protein family and does not belong to the group of glycolytic enzymes. p60 is expressed much more strongly in insect form than in bloodstream form trypanosomes. Thus, p60 is the first glycosomal protein observed whose expression is up-regulated during the transition of trypanosomes from the bloodstream to the insect form. The biochemical characterization of p60 demonstrated its capability to bind microtubules and membrane vesicles and to cross-link these structures. These properties might indicate a function in linking glycosomes to the microtubules of the trypanosomal cytoskeleton. However, proteinase K digestion experiments indicate that p60 is not exposed at the outer surface of the glycosomal membrane. The biological role of the microtubule-binding capability of p60 remains unclear, whereas its membrane binding may be of physiological significance inside the glycosome.

Amino Acid Sequence↗
PubMed1989

Plasmid vector for overproduction and export of recombinant protein in Escherichia coli: efficient one-step purification of a recombinant antigen from Echinococcus multilocularis (Cestoda).

We describe the use of the Escherichia coli plasmid vector, pVB2, for high-level expression and export of recombinant protein. The pBR322 derivative pVB2 harbors the mglB gene, which codes for the galactose-binding protein (GBP) of E. coli. GBP is exported into the periplasmic space of the bacterial cell. Gene mglB contains an EcoRI restriction site close to its 3' end which allows simple in-frame insertion of EcoRI fragments obtained from recombinant lambda gt11 phages. The pVB2 vector was used to express an antigen from Echinococcus multilocularis. The recombinant protein amounted to over 50% of total cellular protein and could be efficiently isolated from the periplasm by osmotic shock. The application of the purified antigen in an ELISA enabled a clear and specific detection of anti-Ec. multilocularis antibodies in human patients' sera, which had been immunosorbed with a periplasmic extract (containing wt GBP) before investigation. These data show the general usefulness of pVB2 as an expression vector for producing in E. coli diagnostically relevant antigens from any infective organism.

Animals↗
PubMed1989

Application of a recombinant Echinococcus multilocularis antigen in an enzyme-linked immunosorbent assay for immunodiagnosis of human alveolar echinococcosis.

A highly antigenic polypeptide fragment of the recombinant Echinococcus multilocularis antigen II/3 was produced in Escherichia coli and purified for application in enzyme-linked immunosorbent assay (ELISA). The antigen II/3-encoding 1.0 kb DNA sequence was reduced by sonication into smaller DNA fragments which were subsequently cloned into lambda gt11. Three clones could be isolated from the sublibrary, all synthesizing a recombinant antigen as a stable beta-galactosidase fusion protein. In a further step, the 0.6-kb insert from one positive clone was subcloned into the plasmid pAR 3038, which directed efficient synthesis of the antigen fused to only 11 amino acids from the N-terminus of the phage T7 major capsid protein. The plasmid-encoded antigen (antigen II/3-10) was purified from a bacterial cell extract and then tested in an ELISA. Using sera from 88 patients with an E. multilocularis-infection, a high diagnostic sensitivity of 90% was demonstrated. Investigation of sera from 220 patients with various helminthic infections showed a specificity of 99%, suggesting the suitability of the antigen II/3-10 as an immunodiagnostic tool.

Animals↗
PubMed1989

The major component of the paraflagellar rod of Trypanosoma brucei is a helical protein that is encoded by two identical, tandemly linked genes.

The flagellum of the parasitic hemoflagellate Trypanosoma brucei contains two major structures: (a) the microtubule axoneme, and (b) a highly ordered, filamentous array, the paraflagellar rod (PFR). This is a complex, three-dimensional structure, of yet unknown function, that extends along most of the axoneme and is closely linked to it. Its major structural component is a single protein of 600 amino acids. This PFR protein can assume two different conformations, resulting in two distinct bands of apparent molecular masses of 73 and 69 kD in SDS-gel electrophoresis. Secondary structure predictions indicate a very high helix content. Despite its biochemical similarity to the intermediate filament proteins (solubility properties, amino acid composition, and high degree of helicity), the PFR protein does not belong in this class of cytoskeletal proteins. The PFR protein is coded for by two tandemly linked genes of identical nucleotide sequence. Both genes are transcribed into stable mRNAs of very similar length that carry the mini-exon sequence at their 5' termini.

Amino Acid Sequence↗