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‣ Phylogenetic relationships and the evolution of mimicry in the Chauliognathus yellow-black species complex (Coleoptera : Cantharidae) inferred from mitochondrial COI sequences

Machado, Vilmar; Araujo, Aldo Mellender de; Serrano, José; Galián, José
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
Português
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The phylogenetic relationships of twelve species of Chauliognathus were investigated by studying the mitochondrial cytochrome oxidase I gene. A 678 bp fragment of the COI gene was sequenced to test the hypothesis that the Müllerian mimicry species of the “yellow-black” complex make up a monophyletic clade, separated from species with other colour patterns. The data set was analysed by neighbour-joining, maximum parsimony and maximum likelihood procedures. The results support a single origin of the yellow-black colour pattern during the evolution of the genus, with one main clade formed by Chauliognathus lineatus, C. tetrapunctatus, C. riograndensis, C. flavipes, C. octomaculatus, C. fallax, and another one formed by two species, C. expansus and C sp 1, plus an orange-black-coloured species. The nucleotide divergences found between C. sp 3 (black) and the other species studied fall within the level expected for species from different genera. The similarity of colour patterns of the yellow-black species has been considered an example of Müllerian mimicry by conservation of the ancestral state with some minor modifications.

‣ Skin glands, poison and mimicry in dendrobatid and leptodactylid amphibians

Prates, Ivan; Antoniazzi, Marta M.; Sciani, Juliana M.; Pimenta, Daniel C.; Toledo, Luis Felipe; Haddad, Celio Fernando Baptista; Jared, Carlos
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica Formato: 279-290
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); In amphibians, secretions of toxins from specialized skin poison glands play a central role in defense against predators. The production of toxic secretions is often associated with conspicuous color patterns that warn potential predators, as it is the case of many dendrobatid frogs, including Ameerega picta. This species resembles the presumably nontoxic Leptodactylus lineatus. This study tests for mimicry by studying the morphology and distribution of skin glands, components of skin secretion, and defensive behavior. Dorsal skin was studied histologically and histochemically, and skin secretions were submitted to sodium dodecyl sulfate polyacrylamide gel electrophoresis, reversed phase high performance liquid chromatography and assays for proteolytic activity. We found that poison glands in A. picta are filled with nonprotein granules that are rich in carbohydrates, while L. lineatus glands present protein granules. Accordingly, great amounts of proteins, at least some of them enzymes, were found in the poison of L. lineatus but not in that of A. picta. Both species differ greatly on profiles of gland distribution: In L. lineatus...

‣ ABO System: molecular mimicry of Ascaris lumbricoides

Ponce de León,Patricia; Valverde,Juana
Fonte: Instituto de Medicina Tropical Publicador: Instituto de Medicina Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2003 Português
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A. lumbricoides has been associated to the ABO System by various authors. The objective was to detect ABO System epitopes in A. lumbricoides of groups O, A, B and AB patients. 28 adult parasites were obtained from children to be used as assay material. The patients ABO blood groups were determined. Extracts of A. lumbricoides [AE] were prepared by surgical remotion of the cuticle and refrigerated mechanical rupture. Agglutination Inhibition (AI) and Hemoagglutination Kinetics (HK) tests were used with the [AE]. Of the 28 [AE], eight belonged to O group patients, 15 to A group, three to B group and the remaining two to AB children. The AI Test showed A epitopes in two [AE] of group A patients and B epitopes in two [AE] of group B patients. The HK Test showed B antigenic determiners in two [AE] of group B patients and in two [AE] of group AB patients as well as A antigenic determiners in one [AE] of A group patient. Of the 28 [AE] studied in both tests B epitopes were detected in all [AE] from B and AB patients and A epitopes in three of the 15 [AE] of group A patients. The experiments carried out suggest that A. lumbricoides might absorb A and B antigens from the host, and/or modify the cuticular carbohydrates expression as a kind of antigenic mimicry.

‣ The aggregation of Chauliognathus species (Coleoptera, Cantharidae) and its possible role for coexistence and mimicry

Machado,Vilmar; Araújo,Aldo Mellender de
Fonte: Fundação Zoobotânica do Rio Grande do Sul Publicador: Fundação Zoobotânica do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2001 Português
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The relative population sizes of a species complex of Chauliognathus are reported, as well as their spatial distribution associated with different patches of food plants. Field work was done at Fazenda Santa Isabel, municipality of Guaíba, State of Rio Grande do Sul, Brazil. The results suggest that two mechanisms account for the reduction in food competition among the species involved: one is asynchrony in the appearance of the species in the area, and the other is aggregation in different patches of food plants. Since the species here reported show a similar colour pattern (yellow-black) the possibility of the occurrence of serial mimicry in this complex of species is dicussed.

‣ Are there evidences of a complex mimicry system among Asclepias curassavica (Apocynaceae), Epidendrum fulgens (Orchidaceae), and Lantana camara (Verbenaceae) in Southern Brazil?

Fuhro,Daniela; Araújo,Aldo Mellender de; Irgang,Bruno Edgar
Fonte: Sociedade Botânica de São Paulo Publicador: Sociedade Botânica de São Paulo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2010 Português
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The goal of this paper was to test the presence of mimicry in Asclepias curassavica L., Epidendrum fulgens Brong., and Lantana camara L. The study was carried out at the Parque Estadual de Itapeva, RS, southern Brazil, from 2004 to 2006. Flowering period of each of the three species was followed up; focal observations of butterflies visiting flowers, from fixed point and during random walks were carried out. We also estimated the frequency of pollinaria removal in the orchid, as well as its mode of reproduction. All these variables were important for testing the mimicry hypothesis. Despite some temporal coincidences in the flowering period of two plants in the system, there was no statistical association among the three plants as to flowering period. Twenty-nine species of butterflies, as potential pollinators, were recorded, particularly Agraulis vanillae maculosa, Dryas iulia alcionea, Urbanus simplicius, Tegosa claudina, and Heliconius erato phyllis, which were the more frequent visitors of the three plants. There was association between the number of visits to L. camara and E. fulgens, based on Pearson correlation (r = 0.4603; n = 19; P = 0.0473). Pollinaria removal of E. fulgens was low, as measured by the percentage of removal (range: 0 - 10%). The analysis of the mode of reproduction of this orchid showed its pollinator-dependence...

‣ Autoimmunity and molecular mimicry in tropical spastic paraparesis/human T-lymphotropic virus-associated myelopathy

García-Vallejo,F.; Domínguez,M.C.; Tamayo,O.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2005 Português
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Viruses share antigenic sites with normal host cell components, a phenomenon known as molecular mimicry. It has long been suggested that viral infections might trigger an autoimmune response by several mechanisms including molecular mimicry. More than 600 antiviral monoclonal antibodies generated against 11 different viruses have been reported to react with 3.5% of cells specific for uninfected mouse organs. The main pathological feature of tropical spastic paraparesis/human T-lymphotropic virus type I (HTLV-I)-associated myelopathy (TSP/HAM) is a chronic inflammation of the spinal cord characterized by perivascular cuffing of mononuclear cells accompanied by parenchymal lymphocytic infiltration. We detected the presence of autoantibodies against a 98- to 100-kDa protein of in vitro cultured human astrocytes and a 33- to 35-kDa protein from normal human brain in the serum of HTLV-I-seropositive individuals. The two cell proteins exhibited molecular mimicry with HTLV-I gag and tax proteins in TSP/HAM patients, respectively. Furthermore, the location of 33- to 35-kDa protein cross-reaction correlated with the anatomical spinal cord areas (in the rat model) in which axonal damage has been reported in several cases of TSP/HAM patients. Our experimental evidence strongly suggests that the demyelinating process occurring in TSP/HAM may be mediated by molecular mimicry between domains of some viral proteins and normal cellular targets of the spinal cord sections involved in the neurodegeneration.

‣ Antigen mimicry followed by epitope spreading: a pathogenetic trigger for the clinical morphology of lichen planus and its transition to Graham Lassueur Piccardi Little Syndrome and keratosis lichenoides chronica - Medical hypotheses or reality?

Tchernev,Georgi; Nenoff,Pietro
Fonte: Sociedade Brasileira de Dermatologia Publicador: Sociedade Brasileira de Dermatologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2009 Português
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Literature data analysis, providing an exact explanation of the lichen planus pathogenesis, as well as its transition into other rare forms such as Keratosis lichenoides chronica or Graham Lassueur Piccardi Little Syndrome are scant, or totally missing. The chronological course of the disease, known in the literature as lichen planus, varies. Some patients develop Lichen planus or lichen nitidus and there is no logical explanation why. It is also not clear why single patients initially develop ulcerative lesions in the area of the mucosa and only in a few of them these lesions affect the skin. Antigen Mimicry and Epitope Spreading could be the possible pathogenic inductor in cases of lichenoid dermatoses, as well as the cause for their transition into ulcerative, exanthematous or other rare forms. The Epitope Spreading is probably not the leading pathogenetic factor in lichen planus but a phenomenon which occurs later. This manuscript analyzes some basic pathogenic aspects and presents some possible medical hypotheses regarding the heterogenic clinical picture and pathogenesis of lichen planus and lichenoid like pathologies of the skin which, in the near future should be analyzed in details in order to clarify several dilemmas the clinical dermatologist has to face.

‣ Phylogenetic relationships and the evolution of mimicry in the Chauliognathus yellow-black species complex (Coleoptera: Cantharidae) inferred from mitochondrial COI sequences

Machado,Vilmar; Araujo,Aldo M.; Serrano,José; Galián,José
Fonte: Sociedade Brasileira de Genética Publicador: Sociedade Brasileira de Genética
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2004 Português
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The phylogenetic relationships of twelve species of Chauliognathus were investigated by studying the mitochondrial cytochrome oxidase I gene. A 678 bp fragment of the COI gene was sequenced to test the hypothesis that the Müllerian mimicry species of the "yellow-black" complex make up a monophyletic clade, separated from species with other colour patterns. The data set was analysed by neighbour-joining, maximum parsimony and maximum likelihood procedures. The results support a single origin of the yellow-black colour pattern during the evolution of the genus, with one main clade formed by Chauliognathus lineatus, C. tetrapunctatus, C. riograndensis, C. flavipes, C. octomaculatus, C. fallax, and another one formed by two species, C. expansus and C sp 1, plus an orange-black-coloured species. The nucleotide divergences found between C. sp 3 (black) and the other species studied fall within the level expected for species from different genera. The similarity of colour patterns of the yellow-black species has been considered an example of Müllerian mimicry by conservation of the ancestral state with some minor modifications.

‣ The association of the goatfish mulloidichthys martinicus with the grunt haemulon chrysargyreum: an example of protective mimicry

Krajewski,João Paulo; Bonaldo,Roberta Martini; Sazima,Cristina; Sazima,Ivan
Fonte: Instituto Virtual da Biodiversidade | BIOTA - FAPESP Publicador: Instituto Virtual da Biodiversidade | BIOTA - FAPESP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2004 Português
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A presumed example of protective mimicry between the yellow goatfish, Mulloidichthys martinicus (Mullidae) and the smallmouth grunt, Haemulon chrysargyreum (Haemulidae) is described from Fernando de Noronha Archipelago, NE Brazil. The goatfish and the grunt share a similar overall shape and colour pattern. We found that these two species regularly form mixed schools around reefs. Additionally, when chased small groups of yellow goatfish join schools of smallmouth grunts and behave like them. The colour and shape resemblances between the two species enable their mixed schooling, and enhance the protection against visually oriented predators for both of them. Thus, we suggest that the protective association herein reported for the goatfish and the grunt may be considered as a “social mimicry”, since neither species is venomous, poisonous or strongly armed. Furthermore, we suggest that additional instances of social mimicry may involve the yellow goatfish and other striped Haemulon species.

‣ Mixed-species schooling behavior and protective mimicry involving coral reef fish from the genus Haemulon (Haemulidae)

Pereira,Pedro Henrique Cipresso; Feitosa,João Lucas Leão; Ferreira,Beatrice Padovani
Fonte: Sociedade Brasileira de Ictiologia Publicador: Sociedade Brasileira de Ictiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 Português
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The present study analyzed heterotypic schooling behavior and protective mimicry relationships involving species of the genus Haemulon and other coral reef fishes on coastal reefs at Tamandaré, Pernambuco State, Northeastern Brazil. The work was performed during 35 hours of direct observation using the "focal animal" method. The observed events involved 14 species of reef fish in eight different families. The phenomenon of mixed schooling appeared to be related to the large number of individuals of the genus Haemulon present in reef environments and to the tendency of individuals with limited populations to try to aggregate in schools (e.g. genus Scarus).

‣ Merkel Cell Carcinoma Expresses Vasculogenic Mimicry: Demonstration in Patients and Experimental Manipulation in Xenografts

Lezcano, Cecilia; Kleffel, Sonja; Lee, Nayoung; Larson, Allison R.; Zhan, Qian; DoRosario, Andrew; Wang, Linda C.; Schatton, Tobias; Murphy, George F.
Fonte: Harvard University Publicador: Harvard University
Tipo: Artigo de Revista Científica
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Merkel cell carcinoma (MCC) is a highly virulent cutaneous neoplasm that, like melanoma, is a frequent cause of patient morbidity and mortality. The cellular mechanisms responsible for the aggressive behavior of MCC remain unknown. Vasculogenic mimicry (VM) is a phenomenon associated with cancer virulence, including in melanoma, whereby anastomosing laminin networks form in association with tumor cells that express certain endothelial genes. To determine whether VM is a factor in MCC, we employed a relevant xenograft model using two independent human MCC lines. Experimentally induced tumors were remarkably similar histologically to patient MCC, and both contained laminin networks associated with vascular endothelial-cadherin (CD144) and vascular endothelial growth factor receptor 1 (VEGFR-1) as well as Nodal expression typical of VM in melanoma. Moreover, two established chemotherapeutic agents utilized for human MCC, etoposide and carboplatin, induced necrosis in xenografts upon systemic administration while enriching for laminin networks in apparently resistant viable tumor regions that persisted. These findings for the first time establish VM-like laminin networks as a biomarker in MCC, demonstrate the experimental utility of the MCC xenograft model...

‣ Genomic hotspots for adaptation: the population genetics of Müllerian mimicry in the Heliconius melpomene clade; Genomic hotspots for adaptation: the population genetics of Mullerian mimicry in the Heliconius melpomene clade

Baxter, S.; Nadeau, N.; Maroja, L.; Wilkinson, P.; Counterman, B.; Dawson, A.; Beltran, M.; Perez-Espona, S.; Chamberlain, N.; Ferguson, L.; Clark, R.; Davidson, C.; Glithero, R.; Mallet, J.; McMillan, W.; Kronforst, M.; Joron, M.; ffrench-Constant, R.; J
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em //2010 Português
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Wing patterning in Heliconius butterflies is a longstanding example of both Müllerian mimicry and phenotypic radiation under strong natural selection. The loci controlling such patterns are “hotspots” for adaptive evolution with great allelic diversity across different species in the genus. We characterise nucleotide variation, genotype-by-phenotype associations, linkage disequilibrium, and candidate gene expression at two loci and across multiple hybrid zones in Heliconius melpomene and relatives. Alleles at HmB control the presence or absence of the red forewing band, while alleles at HmYb control the yellow hindwing bar. Across HmYb two regions, separated by ~100 kb, show significant genotype-by-phenotype associations that are replicated across independent hybrid zones. In contrast, at HmB a single peak of association indicates the likely position of functional sites at three genes, encoding a kinesin, a G-protein coupled receptor, and an mRNA splicing factor. At both HmYb and HmB there is evidence for enhanced linkage disequilibrium (LD) between associated sites separated by up to 14 kb, suggesting that multiple sites are under selection. However, there was no evidence for reduced variation or deviations from neutrality that might indicate a recent selective sweep...

‣ Comparative genomics of the mimicry switch in Papilio dardanus

Timmermans, M.J.T.N.; Baxter, S.W.; Clark, R.; Heckel, D.G.; Vogel, H.; Collins, S.; Papanicolaou, A.; Fukova, I.; Joron, M.; Thompson, M.J.; Jiggins, C.D.; ffrench-Constant, R.H.; Vogler, A.P.
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
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The African Mocker Swallowtail, Papilio dardanus, is a textbook example in evolutionary genetics. Classical breeding experiments have shown that wing pattern variation in this polymorphic Batesian mimic is determined by the polyallelic H locus that controls a set of distinct mimetic phenotypes. Using bacterial artificial chromosome (BAC) sequencing, recombination analyses and comparative genomics,we showthatHco-segregateswith an interval of less than 500 kb that is collinear with two other Lepidoptera genomes and contains 24 genes, including the transcription factor genes engrailed (en) and invected (inv). H is located in a region of conserved gene order, which argues against any role for genomic translocations in the evolution of a hypothesizedmulti-gene mimicry locus. Natural populations of P. dardanus show significant associations of specific morphs with single nucleotide polymorphisms (SNPs), centred on en. In addition, SNP variation in the H region reveals evidence of non-neutral molecular evolution in the en gene alone. We find evidence for a duplication potentially driving physical constraints on recombination in the lamborni morph. Absence of perfect linkage disequilibrium between different genes in the other morphs suggests that H is limited to nucleotide positions in the regulatory and coding regions of en. Our results therefore support the hypothesis that a single gene underlies wing pattern variation in P. dardanus.; Martijn J. T. N. Timmermans...

‣ Chromosomal rearrangements maintain a polymorphic supergene controlling butterfly mimicry

Joron, M.; Frezal, L.; Jones, R.; Chamberlain, N.; Lee, S.; Haag, C.; Whibley, A.; Becuwe, M.; Baxter, S.; Ferguson, L.; Wilkinson, P.; Salazar, C.; Davidson, C.; Clark, R.; Quail, M.; Beasley, H.; Glithero, R.; Lloyd, C.; Sims, S.; Jones, M.; et al.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em //2011 Português
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Supergenes are tight clusters of loci that facilitate the co-segregation of adaptive variation, providing integrated control of complex adaptive phenotypes. Polymorphic supergenes, in which specific combinations of traits are maintained within a single population, were first described for 'pin' and 'thrum' floral types in Primula and Fagopyrum, but classic examples are also found in insect mimicry and snail morphology. Understanding the evolutionary mechanisms that generate these co-adapted gene sets, as well as the mode of limiting the production of unfit recombinant forms, remains a substantial challenge. Here we show that individual wing-pattern morphs in the polymorphic mimetic butterfly Heliconius numata are associated with different genomic rearrangements at the supergene locus P. These rearrangements tighten the genetic linkage between at least two colour-pattern loci that are known to recombine in closely related species, with complete suppression of recombination being observed in experimental crosses across a 400-kilobase interval containing at least 18 genes. In natural populations, notable patterns of linkage disequilibrium (LD) are observed across the entire P region. The resulting divergent haplotype clades and inversion breakpoints are found in complete association with wing-pattern morphs. Our results indicate that allelic combinations at known wing-patterning loci have become locked together in a polymorphic rearrangement at the P locus...

‣ Avian vocal mimicry: a unified conceptual framework

Dalziell, Anastasia H.; Welbergen, Justin A.; Igic, Branislav; Magrath, Robert D.
Fonte: Wiley Publicador: Wiley
Tipo: Artigo de Revista Científica
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Mimicry is a classical example of adaptive signal design. Here, we review the current state of research into vocal mimicry in birds. Avian vocal mimicry is a conspicuous and often spectacular form of animal communication, occurring in many distantly related species. However, the proximate and ultimate causes of vocal mimicry are poorly understood. In the first part of this review, we argue that progress has been impeded by conceptual confusion over what constitutes vocal mimicry. We propose a modified version of Vane-Wright's (1980) widely used definition of mimicry. According to our definition, a vocalisation is mimetic if the behaviour of the receiver changes after perceiving the acoustic resemblance between the mimic and the model, and the behavioural change confers a selective advantage on the mimic. Mimicry is therefore specifically a functional concept where the resemblance between heterospecific sounds is a target of selection. It is distinct from other forms of vocal resemblance including those that are the result of chance or common ancestry, and those that have emerged as a by-product of other processes such as ecological convergence and selection for large song-type repertoires. Thus, our definition provides a general and functionally coherent framework for determining what constitutes vocal mimicry...

‣ The evolution of mimicry in parasites

HURFORD, Hurford, Amy Louise
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
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Parasites may express proteins that mimic host proteins such that the host immune system cannot discriminate between host and parasite. An immune response to host proteins results in autoimmunity, and therefore, mechanisms to avert autoimmunity also limit the capacity of the immune system to respond to parasites that are mimics. In failing to elicit an immune response, parasites that are mimics appear to have a selective advantage and so it is unclear why all parasites do not evolve to be mimics. In this thesis, I demonstrate that next-generation methods can be used to perform an evolutionary invasion analysis. Subsequently, I use this method to identify evolutionarily stable strategies and to investigate three hypotheses for why all parasites are not mimics. These are: (1) that mimicry increases the risk of inducing autoimmunity and that hosts with autoimmunity are less likely to transmit the parasite; (2) that proteins which mimic host proteins have a reduced ability to perform the vital functions necessary for parasite replication; and (3) that owing to a feedback between the types of parasites that infect a host and the host's immune response, when parasites are likely to re-infect the same hosts, mimics are more likely to elicit an immune response. I show that each of these hypotheses explain why all parasites are not mimics. The key data needed to assess the applicability of these results is to quantify the number of secondary infections generated by hosts infected with parasites that are molecular mimics. This thesis motivates a new question in evolutionary epidemiology...

‣ Molecular mimicry between cardiac myosin and Trypanosoma cruzi antigen B13: identification of a B13-driven human T cell clone that recognizes cardiac myosin

Abel,L.C.J.; Kalil,J.; Cunha-Neto,E.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/1997 Português
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Previous reports from our group have demonstrated the association of molecular mimicry between cardiac myosin and the immunodominant Trypanosoma cruzi protein B13 with chronic Chagas' disease cardiomyopathy at both the antibody and heart-infiltrating T cell level. At the peripheral blood level, we observed no difference in primary proliferative responses to T. cruzi B13 protein between chronic Chagas' cardiopathy patients, asymptomatic chagasics and normal individuals. In the present study, we investigated whether T cells sensitized by T. cruzi B13 protein respond to cardiac myosin. T cell clones generated from a B13-stimulated T cell line obtained from peripheral blood of a B13-responsive normal donor were tested for proliferation against B13 protein and human cardiac myosin. The results showed that one clone responded to B13 protein alone and the clone FA46, displaying the highest stimulation index to B13 protein (SI = 25.7), also recognized cardiac myosin. These data show that B13 and cardiac myosin share epitopes at the T cell level and that sensitization of a T cell with B13 protein results in response to cardiac myosin. It can be hypothesized that this also occurs in vivo during T. cruzi infection which results in heart tissue damage in chronic Chagas' disease cardiomyopathy

‣ Evidence for aggressive mimicry in an adult brood parasitic bird, and generalized defences in its host

Feeney, W. E.; Troscianko, J.; Langmore, N. E.; Spottiswoode, C. N.
Fonte: Royal Society Publishing Publicador: Royal Society Publishing
Tipo: Article; published version
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This is the final version of the article. It first appeared from Royal Society Publishing via http://dx.doi.org/10.1098/rspb.2015.079; Mimicry of a harmless model (aggressive mimicry) is used by egg, chick and fledgling brood parasites that resemble the host's own eggs, chicks and fledglings. However, aggressive mimicry may also evolve in adult brood parasites, to avoid attack from hosts and/or manipulate their perception of parasitism risk. We tested the hypothesis that female cuckoo finches (Anomalospiza imberbis) are aggressive mimics of female Euplectes weavers, such as the harmless, abundant and sympatric southern red bishop (Euplectes orix). We show that female cuckoo finch plumage colour and pattern more closely resembled those of Euplectes weavers (putative models) than Vidua finches (closest relatives); that their tawny-flanked prinia (Prinia subflava) hosts were equally aggressive towards female cuckoo finches and southern red bishops, and more aggressive to both than to their male counterparts; and that prinias were equally likely to reject an egg after seeing a female cuckoo finch or bishop, and more likely to do so than after seeing a male bishop near their nest. This is, to our knowledge, the first quantitative evidence for aggressive mimicry in an adult bird...

‣ Immunity and Autoimmunity: Host Mimicry by HIV-1

Yang, Guang
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2015 Português
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Many human monoclonal antibodies that neutralize multiple clades of HIV-1 are polyreactive and bind avidly to mammalian autoantigens. Indeed, the generation of neutralizing antibodies to the 2F5 and 4E10 epitopes of HIV-1 gp41 in man may be proscribed by immune tolerance since mice expressing the VH and VL of 2F5 have an arrested B-cell development characteristic of central tolerance. This developmental blockade implies the presence of tolerizing autoantigens that mitigate effective humoral responses. I hypothesize that discreet human antigens are mimicked by the membrane-proximal external region (MPER) of HIV-1 gp41, and that such mimicry is a wide-spread strategy for HIV-1 to evade immune attacks to its vulnerable neutralizing epitopes.

In the first part of the study, I propose to identify autoantigens mimicked by the 2F5 and 4E10 epitopes. I used immunoprecipitation coupled with mass spectrometry as well as protein arrays to identify the self-antigens recognized by 2F5 and 4E10. The binding of antigens was confirmed using serological assays and targeted mutagenesis was used to map the binding epitope. We identified human kynureninase (KYNU) and splicing factor 3b subunit 3 (SF3B3) as the primary conserved, vertebrate self-antigens recognized by the 2F5 and 4E10 antibodies...

‣ Mimicry of vertebrates: are the rules different?

Pough, F. Harvey
Fonte: University of Chicago Press: American Naturalist Publicador: University of Chicago Press: American Naturalist
Formato: 40288 bytes; application/pdf
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Examples of mimicry among vertebrates are numerically fewer than examples involving insects. The relatively small number of species of vertebrates, compared with the number of species of insects, probably explains some of the apparent scarcity of mimicry. Possibly more important is a mismatch between the primarily visual sensory world of humans and the predominantly chemosensory, auditory, and tactile worlds of most other vertebrates, which has probably concealed many manifestations of mimicry. Systematic investigation of the information that vertebrates convey through these sensory modalities will probably reveal many additional examples of mimicry. Concrete homotypies-those cases in which the model can be identified as a particular species of animal-are widespread among fishes and amphibians and have been suggested for birds and mammals. Both Batesian and Mullerian protective mimicry systems have been described. Because vertebrates grow during their lifetimes without conspicuous changes in morphology, size limitation is manifested in some mimetic systems. Non-protective mimicry also occurs among vertebrates: mimicry of females is an alternative reproductive strategy for males, and many nest parasites mimic the eggs and young of their hosts. Abstract homotypies-cases in which the model cannot be identified as a particular species or group of species-are characteristic of mimicry of venomous snakes. Large body sizes...