ABSTRACT
The scientific publication landscape is changing quickly, with an enormous increase in options and models. Articles can be published in a complex variety of journals that differ in their presentation format (online-only or in-print), editorial organizations that maintain them (commercial and/or society-based), editorial handling (academic or professional editors), editorial board composition (academic or professional), payment options to cover editorial costs (open access or pay-to-read), indexation, visibility, branding, and other aspects. Additionally, online submissions of non-revised versions of manuscripts prior to seeking publication in a peer-reviewed journal (a practice known as pre-printing) are a growing trend in biological sciences. In this changing landscape, researchers in biochemistry and molecular biology must re-think their priorities in terms of scientific output dissemination. The evaluation processes and institutional funding for scientific publications should also be revised accordingly. This article presents the results of discussions within the Department of Biochemistry, University of São Paulo, on this subject.
Subject(s)
Humans , Periodicals as Topic/statistics & numerical data , Publishing/trends , Research , Biochemistry , Molecular Biology , Periodicals as Topic/standards , Periodicals as Topic/trends , BrazilABSTRACT
The aim of the present study was to demonstrate the presence of alpha-L-fucosidase in Trypanosoma cruzi. Immunocytochemical and biochemical techniques were used to localize and characterize a membrane-associated, neutral-pH-optimum, alpha-L-fucosidase from the parasite. Light and electron microscopy localized the alpha-L-fucosidase specifically on the surface of the parasite and on membranes in the posterior region of the epimastigote stage. Although much less intense, labeling was also detected on the surface of trypomastigotes. At least 50 percent of the alpha-L-fucosidase activity was associated with epimastigote membrane solubilized with 1 M NaCl or 1 percent Triton X-100, suggesting that alpha-L-fucosidase is peripherally associated with membranes. The enzyme from epimastigotes had a neutral pH optimum (near 7) but displayed low specific activity when p-nitrophenyl-alpha-L-fucoside was employed as substrate (0.028 U/mg protein for epimastigotes and 0.015 U/mg protein for tissue culture-derived trypomastigotes). Polyacrylamide gel electrophoresis and Western blotting analysis both showed an expected 50-kDa polypeptide which was immunoreactive with anti-alpha-L-fucosidase antibodies
Subject(s)
Animals , alpha-L-Fucosidase , Trypanosoma cruzi , Blotting, Western , Electrophoresis, Polyacrylamide Gel , Hydrogen-Ion Concentration , Immunohistochemistry , Microscopy, Electron , Trypanosoma cruziABSTRACT
Recent research has shown that receptor-ligand interactions between surfaces of communicating cells are necessary prerequisites for cell proliferation, cell differentiation and immune defense. Cell-adhesion events have also been proposed for pathological conditions such as cancer growth, metastasis, and host-cell invasion by parasites such as Trypanosoma cruzi. RNA and DNA aptamers (aptus = Latin, fit) that have been selected from combinatorial nucleic acid libraries are capable of binding to cell-adhesion receptors leading to a halt in cellular processes induced by outside signals as a consequence of blockage of receptor-ligand interactions. We outline here a novel approach using RNA aptamers that bind to T. cruzi receptors and interrupt host-cell invasion in analogy to existing procedures of blocking selectin adhesion and function in vitro and in vivo
Subject(s)
Humans , Cell Adhesion Molecules/physiology , DNA/metabolism , RNA-Binding Proteins/metabolism , RNA/metabolism , Trypanosoma cruzi , Cell Adhesion , Chagas Disease/parasitology , DNA/chemistry , DNA/isolation & purification , Host-Parasite Interactions , Integrins/metabolism , L-Selectin/analysis , P-Selectin/analysis , Protozoan Proteins/chemistry , Protozoan Proteins/metabolism , RNA/chemistry , RNA/isolation & purification , Trypanosoma cruzi/metabolismABSTRACT
Tc-85 is an 85-kDa surface glycoprotein specific for the trypomastigote stage of Tripanosoma cruzi which has been implicated in the invasion of host cells by the parasite. Tc-85 has a half-life of 3.5-4 h and is synthesized as a 95-kDa precursor. Processing of the 95-kDa precursor is inhibited by N-p-tosyl-L-lysine chloromethyl ketone, p-chloromercuriphenylsulfonic acid, iodoacetamide or N-ethylmaleimide, but not by aprotinin, antipain or phenylmethylsulfonil fluoride. Tc-85, but not the precursor, is rapidly shed into the medium, allowing a correlation between the decrease of Tc-85 in trypomastigotes and its increase in the culture medium. The shedding of Tc-85 was inhibited 50 per cent by 1 muM tunicamycin, but not by 10 muM swainsonine or 10 muM 1-deoxynojirimycin under the experimental conditions employed. This suggests that N-linked oligosaccharides are important for the shedding phenomenon, although it appears that they do not have to be fully processed for shedding to occur.
Subject(s)
Membrane Glycoproteins/biosynthesis , Trypanosoma cruzi/metabolism , Electrophoresis, Polyacrylamide Gel , Membrane Glycoproteins/metabolism , Trypanosoma cruzi/metabolismABSTRACT
The bindings of 125I-laminin to trypomastigotes is specific and 2-5 x 10**3 laminin-binding sites were calculated to be presented on the surface of a live trypomastigote. Anti-laminin antibodies were able to inhibit the invasion of cultured cells by trypomastigotes (62-75 per cent), suggesting that laminin may be involved in the adhesion of the parasite to host cells. By affinity chromatography, an 85-KDa glycoprotein was isolated (laminin-bindign glycoprotein, LBG) from trypomastigote lysates, but not from epimastigote lysates. It is suggested that at least fragment E8 (but not E1) from laminin could be involbed in the reaction which is independent of the carbohydrate moieties from both ligand and recepto. It is also shown that LBG is member of the Tc-85 family, previously shown to be related to the invasion process of the parasite
Subject(s)
Animals , Carbohydrates/metabolism , Laminin/metabolism , Protozoan Proteins/metabolism , Trypanosoma cruzi/metabolism , Antibodies, Monoclonal , Binding Sites , Glycoproteins/isolation & purification , Glycoproteins/metabolism , Laminin/antagonists & inhibitors , Laminin/immunology , Peptide Fragments/isolation & purification , Peptide Fragments/metabolism , Protozoan Proteins/isolation & purification , Carrier Proteins/isolation & purification , Carrier Proteins/metabolism , Trypanosoma cruzi/pathogenicityABSTRACT
A hydrophobic fraction isolated from trypomastigotes of Trypanosoma cruzi is being characterized using immunological and chemical techniques. The lipopeptidophosphoglycan (LPPG) was identified in this fraction since it gave a positive reaction with anti-LPPG rabbit serum and had similar structural features such as the presence of ceramide as the lipid moiety, furanoic galactose, and a glycan moiety consistent with that obtained from an authentic sample of epimastigote LPPG, as judged by thin-layer chromatography. Furthermore, the hydrophobic fraction contained other glycolipids with different structural features. The lipid moiety of these compounds is alkylglycerol rather than a ceramide, the carbohydrate chain appears to be less complex than that in LPPG and no reactivity was observed towards an anti-LPPG serum
Subject(s)
Animals , Rabbits , Glycoconjugates/chemistry , Peptidoglycan/chemistry , Phospholipids/chemistry , Trypanosoma cruzi/chemistry , Blotting, Western , Carbohydrate Sequence , Glycoproteins/immunology , Glycoproteins/chemistry , Glycoconjugates/immunology , Molecular Sequence Data , Peptidoglycan/immunology , Phospholipids/immunology , Trypanosoma cruzi/immunologyABSTRACT
amento. Encontrou-se um porcentual de curas