Male behavior in colonies of the social wasp Polistes lanio (Hymenoptera, Vespidae)

Sixteen post-emergent colonies of Polistes lanio were studied while producing males in the course of the colonial cycle. Individually, they remained in the nest only 10.5 days (5-31, n=165). Twelve different male behaviors were observed: remaining immobile on the nest (82,8%), giving alarm (4,8%), flying out from the nest (2,4%), copulating on the nest (2,4%), being dominated (1,6%), self-grooming (1,2%), checking cells (1,2%), adult-adult trophallaxis (receiving food) (0,8%), larva-adult trophallaxis (0,8%), chewing prey and giving it to the larvae (0,8%), returning to the nest without food (0,8%), and fanning the nest (0,4%). In comparison to the behavioral repertory of females (28 items), they performed fewer tasks and remained immobile most of the time on the nest. Their behavior was largely related to self maintenance, but also included giving chewed prey to the larvae, giving alarm signals and fanning the nest.

Análise proteômica do veneno da vespa social Polistes lanio lanio (Hymenoptera; vespidae)

Os venenos dos insetos da ordem Hymenoptera (abelhas, vespas e formigas) são responsáveis por um grande número de acidentes causados por ferroadas. Estes acidentes podem produzir uma série de reações, variando desde uma reação local, até uma reação sistêmica e anafilaxia. Estudos mostraram que 0,8% a 5% da população mundial sofrem de reações sistêmicas generalizadas após ferroadas de insetos pertencentes à ordem Hymenoptera. As espécies pertencentes ao gênero Polistes são tipicamente encontradas no sudeste do Brasil, causando muitos acidentes por ferroadas devido principalmente à proximidade dos ninhos destes insetos das habitações humanas. P.lanio lanio é uma das vespas sociais que mais causam acidentes no Estado de São Paulo e pouco se sabe sobre a composição de seu veneno. As vespas do gênero Polistes são capazes de ferroar múltiplas vezes e causar reações alérgicas severas. Dessa forma, a identificação das proteínas mais abundantes do veneno da vespa social Polistes lanio lanio por uma abordagem proteômica, se faz necessária para uma melhor compreensão dos mecanismos de ação desse veneno. A identificação de várias proteínas do veneno de P. l. lanio, revelou importantes aspectos sobre o processo de envenenamento por vespas do gênero Polistes, os quais podem ajudar no melhor entendimento dos mecanismos de ação destes venenos. A compreensão dos principais alérgenos é uma etapa importante para o desenvolvimento de novos extratos específicos para diagnósticos de alergia e imunoterapia de pacientes sensíveis ao veneno de vespas.

Validation of a mutant of the pore-forming toxin sticholysin-I for the construction of proteinase-activated immunotoxins

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The membranotropic activity of N-terminal peptides from the pore-forming proteins sticholysin I and II is modulated by hydrophobic and electrostatic interactions as well as lipid composition

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Correlations between differences in amino-terminal sequences and different hemolytic activity of sticholysins

Sticholysins I and II (St I and St II) are cytolysins produced by the sea anemone Stichodactyla helianthus. In spite of their 93% sequence homology, St II is more hemolytic against human erythrocytes than St 1. In order to establish the possible causes of this difference, we studied the hemolytic activity of synthetic peptides containing sequences from the N-termini of both proteins. The results demonstrated that the differences in hemolytic activity of the toxins could be ascribed at least partly to differences in their N-termini. (c) 2007 Elsevier Ltd. All rights reserved.

Model peptides mimic the structure and function of the N-terminus of the pore-forming toxin sticholysin II

To investigate the role of the N-terminal region in the lytic mechanism of the pore-forming toxin sticholysin II (St II), we studied the conformational and functional properties of peptides encompassing the first 30 residues of the protein. Peptides containing residues 1-30 (P1-30) and 11-30 (P11-30) were synthesized and their conformational properties were examined in aqueous solution as a function of peptide concentration, pH, ionic strength, and addition of the secondary structure-inducing solvent trifluoroethanol (TFE). CD spectra showed that increasing concentration, pH, and ionic strength led to aggregation of P1-30; as a consequence, the peptide acquired beta-sheet conformation. In contrast, P11-30 exhibited practically no conformational changes under the same conditions, remaining essentially structureless. Moreover, this peptide did not undergo aggregation. These differences clearly point to the modulating effect of the first 10 hydrophobic residues on the peptides aggregation and conformational properties. In TFE both the first ten hydrophobic peptides acquired alpha-helical conformation, albeit to a different extent, P11-30 displayed lower alpha-helical content. P1-30 presented a larger-fraction of residues in alpha-helical conformation in TFE than that found in St II's crystal structure for that portion of the protein. Since TFE mimics the membrane em,, such increase in helical content could also occur upon toxin binding to membranes and represent a step in the mechanism of pore formation. The peptides conformational properties correlated well with their functional behaviour. Thus, P1-30 exhibited much higher hemolytic activity than P11-30. In addition, P11-30 was able to block the toxin's hemolytic activity. The size of pores formed in red blood cells by P 1-30 was estimated by measuring the permeability PEGs of different molecular mass. The pore radius (0.95 +/- 0.01 nm) was very similar to that of the PEGs of different pore formed by the toxin. The results demonstrate that the synthetic peptide P1-30 is a good model of St 11 conformation and function and emphasize the contribution of the toxin's N-terminal region, and, in particular, the hydrophobic residues 1-10 to pore formation. (c) 2005 Wiley Periodicals, Inc.

Hyaluronidase from the venom of the social wasp Polybia paulista (Hymenoptera, Vespidae): Cloning, structural modeling, purification, and immunological analysis

In this study, we describe the cDNA cloning, sequencing, and 3-D structure of the allergen hyaluronidase from Polybia paulista venom (Pp-Hyal). Using a proteomic approach, the native form of Pp-Hyal was purified to homogeneity and used to produce a Pp-specific polyclonal antibody. The results revealed that Pp-Hyal can be classified as a glycosyl hydrolase and that the full-length Pp-Hyal cDNA (1315 bp; GI: 302201582) is similar (80-90%) to hyaluronidase from the venoms of endemic Northern wasp species. The isolated mature protein is comprised of 338 amino acids, with a theoretical pI of 8.77 and a molecular mass of 39,648.8 Da versus a pI of 8.13 and 43,277.0 Da indicated by MS. The Pp-Hyal 3D-structural model revealed a central core (α/β)7 barrel, two sulfide bonds (Cys 19-308 and Cys 185-197), and three putative glycosylation sites (Asn79, Asn187, and Asn325), two of which are also found in the rVes v 2 protein. Based on the model, residues Ser299, Asp107, and Glu109 interact with the substrate and potential epitopes (five conformational and seven linear) located at surface-exposed regions of the structure. Purified native Pp-Hyal showed high similarity (97%) with hyaluronidase from Polistes annularis venom (Q9U6V9). Immunoblotting analysis confirmed the specificity of the Pp-Hyal-specific antibody as it recognized the Pp-Hyal protein in both the purified fraction and P. paulista crude venom. No reaction was observed with the venoms of Apis mellifera, Solenopsis invicta, Agelaia pallipes pallipes, and Polistes lanio lanio, with the exception of immune cross-reactivity with venoms of the genus Polybia (sericea and ignobilis). Our results demonstrate cross-reactivity only between wasp venoms from the genus Polybia. The absence of cross-reactivity between the venoms of wasps and bees observed here is important because it allows identification of the insect responsible for sensitization, or at least of the phylogenetically closest insect, in order to facilitate effective immunotherapy in allergic patients. © 2013 Elsevier Ltd.

Structural and electrical properties of LaNiO3 thin films grown on (100) and (001) oriented SrLaAlO4 substrates by chemical solution deposition method

LaNiO3 thin films were deposited on SrLaAlO4 (1 0 0) and SrLaAlO4 (0 0 1) single crystal substrates by a chemical solution deposition method and heat-treated in oxygen atmosphere at 700° C in tube oven. Structural, morphological, and electrical properties of the LaNiO 3 thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and electrical resistivity as temperature function (Hall measurements). The X-ray diffraction data indicated good crystallinity and a structural preferential orientation. The LaNiO3 thin films have a very flat surface and no droplet was found on their surfaces. Samples of LaNiO3 grown onto (1 0 0) and (0 0 1) oriented SrLaAlO4 single crystal substrates reveled average grain size by AFM approximately 15-30 nm and 20-35 nm, respectively. Transport characteristics observed were clearly dependent upon the substrate orientation which exhibited a metal-to-insulator transition. The underlying mechanism is a result of competition between the mobility edge and the Fermi energy through the occupation of electron states which in turn is controlled by the disorder level induced by different growth surfaces. © 2013 Elsevier Ltd and Techna Group S.r.l.

Functional and Topological Studies with Trp-Containing Analogs of the Peptide StII(1-30) Derived From the N-Terminus of the Pore Forming Toxin Sticholysin II: Contribution to Understand its Orientation in Membrane

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