RESUMO
Diamond nanothreads (DNTs) are fully sp3-bonded one-dimensional carbon nanostructures, synthesized recently through compression of crystalline benzene. They possess outstanding mechanical strength, suitable for the development of novel nanostructured reinforced materials. In this article, we use density functional theory calculations to investigate the feasibility and physical properties of functionalized DNTs. We show that the stacking and covalent bonding of benzene derivative molecules (toluene, aniline, phenol and fluorobenzene) may lead to stable configurations analogous to benzene-derived DNTs, with functional groups (-CH3, -NH2, -OH, -F) covalently attached to the surface. The same principle was also applied to pyridine, an aromatic heterocyclic compound, resulting in DNTs containing N heteroatoms within the sp3 C-C chain. We show that the mechanical properties remain practically unaltered compared to the original material, and that the electronic properties can be tuned upon functionalization. The presence of polar functional groups on DNT surfaces are expected to affect their compatibility with other materials and solvents, enabling the development of novel processes and technological applications using DNTs.
RESUMO
Chagas' disease, caused by Trypanosoma cruzi, is an urgent and highly prevalent danger that is endemic to Latin America, and which the research community continues to ignore. Each year, Chagas' disease kills more people in Latin America compared to any other parasite-borne disease, including malaria. In addition, between 15 and 18 million people worldwide are afflicted with this potentially lethal disease. Despite these devastating numbers, less than 0.5% of worldwide research and development for neglected diseases was aimed at Chagas' disease. The aim of this review is to draw the attention of biotechnologists to the intriguing parasite that causes Chagas' disease, which is T. cruzi. Additionally, we would also like to convince the community that basic science research can have a profound impact on the diagnosis and treatment of Chagas' disease. In this review, we introduce distinct features of T. cruzi such as its complex life cycle (e.g. the potentially infective extracellular amastigote form), its genome and genomics, as well as proteomic analysis of this parasite. Notably, the PIK pathway has been widely acknowledged as an excellent target for drug discovery to combat this pathogen. Furthermore we also describe how the identification and characterization of PIK genes can aid in neutralizing Trypanosoma infections.
Assuntos
Doença de Chagas/parasitologia , Transdução de Sinais/fisiologia , Trypanosoma cruzi/fisiologia , Trypanosoma cruzi/patogenicidade , Animais , Doença de Chagas/tratamento farmacológico , Descoberta de Drogas , Humanos , Insetos Vetores/parasitologia , Insetos Vetores/fisiologia , Estágios do Ciclo de Vida/fisiologia , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Trypanosoma cruzi/genéticaRESUMO
Diagnosis of individuals infected by Trypanosoma cruzi is performed mainly by serological tests using crude antigens, which might crossreact with other infections. In the past ten years, many recombinant T. cruzi proteins and synthetic peptides have been described, and some are already on the market. Managers of laboratories and blood banks need to make decisions on a cost-benefit basis whether to include these new-generation tests. Here, we indicate antigens that are likely to prove most useful.
Assuntos
Antígenos de Protozoários/imunologia , Doença de Chagas/diagnóstico , Trypanosoma cruzi/imunologia , Animais , Bancos de Sangue , Análise Custo-Benefício , Ensaio de Imunoadsorção Enzimática , Humanos , Estudos Multicêntricos como Assunto , Kit de Reagentes para Diagnóstico/economia , Proteínas Recombinantes/imunologia , Testes Sorológicos/métodos , Organização Mundial da SaúdeRESUMO
As part of the Trypanosoma cruzi Genome Initiative, we have mapped a large portion of the chromosomal bands XVI (2.3 Mb) and XVII (2.6 Mb) containing the highly repetitive and immunodominant antigenic gene families h49 and jl8. Restriction mapping of the isolated chromosomal bands and hybridization with chromosome specific gene probes showed that genes h49 and jl8 are located in a pair of size-polymorphic homologous chromosomes. To construct the integrated map of the chromosomes harboring the h49 and jl8 loci, we used YAC, cosmid, and lambda phage overlapping clones, and long range restriction analysis using a variety of probes (i.e., known gene sequences, ESTs, polymorphic repetitive sequences, anonymous sequences, STSs generated from the YAC ends). The total length covered by the YAC contig was approximately 670 kb, and its map agreed and was complementary to the one obtained by long-range restriction fragment analysis. Average genetic marker spacing in a 105 kb region around h49 and jl8 genes was estimated to be 6.2 kb/marker. We have detected some polymorphism in the H49/JL8 antigens-encoding chromosomes, affecting also the coding regions. The physical map of this region, together with the isolation of specific chromosome markers, will contribute in the global effort to sequence the nuclear genome of this parasite.
Assuntos
Antígenos de Protozoários/genética , Mapeamento Físico do Cromossomo , Trypanosoma cruzi/genética , Animais , Bandeamento Cromossômico , Cromossomos Artificiais de Levedura/genética , Mapeamento de Sequências Contíguas , Sondas de DNA/genética , DNA de Protozoário/química , DNA de Protozoário/isolamento & purificação , Genes de Protozoários/genética , Humanos , Epitopos Imunodominantes/genética , Mapeamento por Restrição , Homologia de Sequência do Ácido NucleicoRESUMO
Metacyclic trypomastigotes of Trypanosoma cruzi express a developmentally regulated 82 kDa surface glycoprotein (gp82) that has been implicated in the mammalian cell invasion. When the non-infective epimastigote stage of the parasite was transfected with a vector containing the gp82 gene, an 82 kDa surface glycoprotein, which was indistinguishable from the metacyclic stage protein, was expressed. In contrast, when the same gene was expressed in transfected mammalian cells, although a large amount of protein was produced, it was not imported into the endoplasmic reticulum and glycosylated. This blockage in targeting and processing could be partially compensated for by the addition of a virus haemagglutinin signal peptide to the amino terminus of gp82. Thus, the requirements for membrane protein processing are distinct in mammals and T. cruzi, and an intrinsic feature of the gp82 prevents subsequent sorting to the mammalian cell surface. These results could be useful in the development of new DNA vaccines against T. cruzi employing parasite genes encoding immunodominant surface glycoproteins.
Assuntos
Glicoproteínas de Membrana/genética , Processamento de Proteína Pós-Traducional , Sinais Direcionadores de Proteínas , Trypanosoma cruzi/genética , Sequência de Aminoácidos , Animais , Chlorocebus aethiops , Clonagem Molecular , Cães , Glicosilação , Mamíferos , Glicoproteínas de Membrana/metabolismo , Dados de Sequência Molecular , Transfecção , Células VeroRESUMO
Peptides derived from the surface glycoprotein gp82 of Trypanosoma cruzi, previously implicated in the parasite's invasion of host cells, were expressed as fusions to the protein LamB of Escherichia coli in a region known to be exposed on the cell surface. Bacteria expressing these proteins adhered to HeLa cells in a manner that mimics the pattern of parasite invasion of mammalian cells. Purified LamB fusion proteins were shown to bind to HeLa cells and to inhibit infection by T. cruzi, supporting the notion that these gp82-derived peptides can mediate interaction of the parasite with its host.
Assuntos
Aderência Bacteriana/fisiologia , Proteínas da Membrana Bacteriana Externa/metabolismo , Escherichia coli/fisiologia , Glicoproteínas de Membrana/metabolismo , Proteínas de Protozoários/metabolismo , Receptores Virais/metabolismo , Trypanosoma cruzi , Sequência de Aminoácidos , Animais , Proteínas da Membrana Bacteriana Externa/genética , Expressão Gênica , Células HeLa , Humanos , Glicoproteínas de Membrana/genética , Dados de Sequência Molecular , Peptídeos/metabolismo , Porinas , Proteínas de Protozoários/genética , Receptores Virais/genética , Proteínas Recombinantes de Fusão/genética , Trypanosoma cruzi/patogenicidadeRESUMO
The commercially available diagnostic tests for Chagas' disease employ whole extracts or semipurified fractions of Trypanosoma cruzi epimastigotes. Considerable variation in the reproducibility and reliability of these tests has been reported by different research laboratories, mainly due to cross-reactivity with other pathogens and standardization of the reagents. The use of recombinant antigens for the serodiagnosis of Chagas' disease is recommended to increase the sensitivity and specificity of serological tests. Expressed in Escherichia coli, as fusion products with glutathione S-transferase, six T. cruzi recombinant antigens (H49, JL7, A13, B13, JL8, and 1F8) were evaluated in an enzyme-linked immunosorbent assay for Chagas' disease. The study was carried out with a panel of 541 serum samples of chagasic and nonchagasic patients from nine countries of Latin America (Argentina, Bolivia, Brazil, Chile, Colombia, El Salvador, Guatemala, Honduras, and Venezuela). The optimal concentration of each recombinant antigen for coating of plates was determined with the help of 125I-labelled recombinant proteins. While the specificity of the epimastigote antigen was 84% because of false positives from leishmaniasis cases, for the recombinant antigens it varied from 96.2 to 99.6%. Recombinant antigens reacted with 79 to 100% of serum samples from chronic chagasic patients. In this way, it is proposed that a mixture of a few T. cruzi recombinant antigens should be employed in a diagnostic kit to minimize individual variation and promote high sensitivity in the diagnosis of Chagas' disease.