Learning spatial aversion is sensory-specific in the hematophagous insect Rhodnius prolixus

Even though innate behaviors are essential for assuring quick responses to expected stimuli, experience-dependent behavioral plasticity confers an advantage when unexpected conditions arise. As being rigidly responsive to too many stimuli can be biologically expensive, adapting preferences to time-dependent relevant environmental conditions provide a cheaper and wider behavioral reactivity. According to their specific life habits, animals prioritize different sensory modalities to maximize environment exploitation. Besides, when mediating learning processes, the salience of a stimulus usually plays a relevant role in determining the intensity of an association. Then, sensory prioritization might reflect an heterogeneity in the cognitive abilities of an individual. Here, we analyze in the kissing bug Rhodnius prolixus if stimuli from different sensory modalities generate different cognitive capacities under an operant aversive paradigm. In a 2-choice walking arena, by registering the spatial distribution of insects over an experimental arena, we evaluated firstly the innate responses of bugs confronted to mechanical (rough substrate), visual (green light), thermal (32°C heated plate), hygric (humidified substrate), gustatory (sodium chloride), and olfactory (isobutyric acid) stimuli. In further experimental series bugs were submitted to an aversive operant conditioning by pairing each stimulus with a negative reinforcement. Subsequent tests allowed us to analyze if the innate behaviors were modulated by such previous aversive experience. In our experimental setup mechanical and visual stimuli were neutral, the thermal cue was attractive, and the hygric, gustatory and olfactory ones were innately aversive. After the aversive conditioning, responses to the mechanical, the visual, the hygric and the gustatory stimuli were modulated while responses to the thermal and the olfactory stimuli remained rigid. We present evidences that the spatial learning capacities of R. prolixus are dependent on the sensory modality of the conditioned stimulus, regardless their innate valence (i.e., neutral, attractive, or aversive). These differences might be given by the biological relevance of the stimuli and/or by evolutionary aspects of the life traits of this hematophagous insect.Fil: Minoli, Sebastian. Universidad de Buenos Aires; ArgentinaFil: Cano, Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pontes, Gina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Magallanes, Amorina. Universidad de Buenos Aires; ArgentinaFil: Roldán, Nahuel. Universidad de Buenos Aires; ArgentinaFil: Barrozo, Romina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Characterization of the sensory gene repertoire of Triatoma infestans and the effect of blood ingestion on its antennal expression

Currently, Triatoma infestans is the main vector of Chagas disease in Argentina, Paraguay, and Bolivia. As many T. infestans populations present insecticide resistance, directly impacting control campaigns, alternative control methods, like those based on behavioral manipulation are needed. Bug nutritional and developmental status modulate bug responsiveness to host-related sensory cues. In order to understand the molecular bases of this modulation, we sequenced the antennal transcriptome of T. infestans and compared the gene expression profiles between unfed and fed insects.Para acceder a la videoconferencia completa, hacer clic en "Enlace externo".Sociedad Latinoamericana de Ecología de Vectore

Streptococcus pyogenes Causing Skin and Soft Tissue Infections Are Enriched in the Recently Emerged emm89 Clade 3 and Are Not Associated With Abrogation of CovRS

Although skin and soft tissue infections (SSTI) are the most common focal infections associated with invasive disease caused by Streptococcus pyogenes (Lancefield Group A streptococci - GAS), there is scarce information on the characteristics of isolates recovered from SSTI in temperate-climate regions. In this study, 320 GAS isolated from SSTI in Portugal were characterized by multiple typing methods and tested for antimicrobial susceptibility and SpeB activity. The covRS and ropB genes of isolates with no detectable SpeB activity were sequenced. The antimicrobial susceptibility profile was similar to that of previously characterized isolates from invasive infections (iGAS), presenting a decreasing trend in macrolide resistance. However, the clonal composition of SSTI between 2005 and 2009 was significantly different from that of contemporary iGAS. Overall, iGAS were associated with emm1 and emm3, while SSTI were associated with emm89, the dominant emm type among SSTI (19%). Within emm89, SSTI were only significantly associated with isolates lacking the hasABC locus, suggesting that the recently emerged emm89 clade 3 may have an increased potential to cause SSTI. Reflecting these associations between emm type and disease presentation, there were also differences in the distribution of emm clusters, sequence types, and superantigen gene profiles between SSTI and iGAS. According to the predicted ability of each emm cluster to interact with host proteins, iGAS were associated with the ability to bind fibrinogen and albumin, whereas SSTI isolates were associated with the ability to bind C4BP, IgA, and IgG. SpeB activity was absent in 79 isolates (25%), in line with the proportion previously observed among iGAS. Null covS and ropB alleles (predicted to eliminate protein function) were detected in 10 (3%) and 12 (4%) isolates, corresponding to an underrepresentation of mutations impairing CovRS function in SSTI relative to iGAS. Overall, these results indicate that the isolates responsible for SSTI are genetically distinct from those recovered from normally sterile sites, supporting a role for mutations impairing CovRS activity specifically in invasive infection and suggesting that this role relies on a differential regulation of other virulence factors besides SpeB

Streptococcus canis Are a Single Population Infecting Multiple Animal Hosts Despite the Diversity of the Universally Present M-Like Protein SCM

Streptococcus canis is an animal pathogen which occasionally causes infections in humans. The S. canis M-like protein (SCM) encoded by the scm gene, is its best characterized virulence factor but previous studies suggested it could be absent in a substantial fraction of isolates. We studied the distribution and variability of the scm gene in 188 S. canis isolates recovered from companion animals (n = 152), wild animal species (n = 20), and humans (n = 14). Multilocus sequence typing, including the first characterization of wildlife isolates, showed that the same lineages are present in all animal hosts, raising the possibility of extensive circulation between species. Whole-genome analysis revealed that emm-like genes found previously in S. canis correspond to divergent scm genes, indicating that what was previously believed to correspond to two genes is in fact the same scm locus. We designed primers allowing for the first time the successful amplification of the scm gene in all isolates. Analysis of the scm sequences identified 12 distinct types, which could be divided into two clusters: group I (76%, n = 142) and group II (24%, n = 46) sharing little sequence similarity. The predicted group I SCM showed extensive similarity with each other outside of the N-terminal hypervariable region and a conserved IgG binding domain. This domain was absent from group II SCM variants found in isolates previously thought to lack the scm gene, which also showed greater amino acid variability. Further studies are necessary to elucidate the possible host interacting partners of the group II SCM variants and their role in virulence

Comportamento sexual de Rhodnius prolixus (Heteroptera: Reduviidae).

Submitted by Nuzia Santos ([email protected]) on 2017-08-24T18:12:29Z No. of bitstreams: 1 Gina Barcelos Pontes.pdf: 2706332 bytes, checksum: 7221a4034541a3e6ae01bb82d4ee0d3a (MD5)Approved for entry into archive by Nuzia Santos ([email protected]) on 2017-08-24T18:18:34Z (GMT) No. of bitstreams: 1 Gina Barcelos Pontes.pdf: 2706332 bytes, checksum: 7221a4034541a3e6ae01bb82d4ee0d3a (MD5)Made available in DSpace on 2017-08-24T18:18:35Z (GMT). No. of bitstreams: 1 Gina Barcelos Pontes.pdf: 2706332 bytes, checksum: 7221a4034541a3e6ae01bb82d4ee0d3a (MD5) Previous issue date: 2010CAPES/MINCyTFAPEMIGCNPqFundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Belo Horizonte, MG, Brasil.Este estudo descreveu a dinâmica de uso de abrigos em adultos de Rhodnius prolixus evidenciando que a saída dos abrigos e a atividade locomotora dos machos são moduladas por sinais olfativos sexuais emitidos por fêmeas. Adicionalmente, foram analisadas a frequência de início do vôo, e a atividade locomotora durante a marcha, a fim de avaliar as hipóteses de que haveri a ativação e orientação mediante sinais químicos emitidos por indivíduos do sexo opo sto. Além disso, verificamos o comportamento de agregação de machos ao redor de ca sais em cópula. Os odores das fêmeas foram capazes de induzir a saída dos mac hos dos abrigos, além de aumentar a atividade locomotora destes. Odores de f êmeas originados das glândulas metasternais promoveram um aumento na fre quência de inicio do voo de machos de R. prolixus. Além disso, estes sinais olfativos modularam a ori entação anemotática observada durante a marcha dos machos. Nossos achados demonstraram que na ausência dos odores das glândul as metasternais de fêmeas, o comportamento de agregação dos machos durante a c ópula é drasticamente afetado. Desta forma, concluímos que os odores prod uzidos pelas glândulas metasternais das fêmeas são de grande relevância no comportamento sexual de R. prolixus , já que na ausência destes, alguns mecanismos que medeiam o comportamento sexual desta espécie foram prejudicad os.This study described the dynamics of the use of she lters by adult Rhodnius prolixus showing that male activation in shelters and subseq uent locomotor activity are induzed by olfactory signals emitted by females. We analyzed both flight initiation frequency and orientation during locomotion, consid ering that insects should activate and engage in oriented responses if chemical signal s were emitted by individuals of the opposite sex. Furthermore, we evaluated the agg regation behavior of males to search for the source of the chemical signal. Femal e odors were able to induce males to leave their shelters and increased their l ocomotor activity. Female odors originated in metasternal glands promoted an increa se in take-off frequency in males. Moreover, these olfactory signals were also relevan t for the expression of an anemotactic response by walking males. Our findings suggest that in the absence of female metasternal gland odors, the aggregation beh avior of males during copulation is not expressed. Thus, we conclude that the odors produced by glands metasternal are a key set of signals mediating the sexual behav ior of R.prolixus

Sinais químicos envolvidos no comportamento sexual de Rhodnius prolixus Stål, 1859(Hemiptera, Reduviidae).

Submitted by Nuzia Santos ([email protected]) on 2017-08-24T18:01:23Z No. of bitstreams: 1 Gina Barcelos Pontes.pdf: 697310 bytes, checksum: d325bade4e19e0adc49919cc0adfe30e (MD5)Approved for entry into archive by Nuzia Santos ([email protected]) on 2017-08-24T18:06:33Z (GMT) No. of bitstreams: 1 Gina Barcelos Pontes.pdf: 697310 bytes, checksum: d325bade4e19e0adc49919cc0adfe30e (MD5)Made available in DSpace on 2017-08-24T18:06:33Z (GMT). No. of bitstreams: 1 Gina Barcelos Pontes.pdf: 697310 bytes, checksum: d325bade4e19e0adc49919cc0adfe30e (MD5) Previous issue date: 2007Instituto René RachouCAPESFundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Belo Horizonte, MG, Brasil.Rhodnius prolixus é o principal vetor da doença de Chagas no norte da América do Sul e na América Central. Triatomí neos adultos possuem um par de glândulas metasternais (GM) localizadas no metatórax ventral. Alguns estudos discutem a participação das GMs na comunicação sexual em triatomíneos. Até o momento, a função das GMs de R. prolixus, assim como a identidade da suas secreções são desconhecidas. Assim, o objetivo deste estudo foi identificar os compostos presentes nas GMs de R. prolixus, bem como estudar o envolvimento destes compostos no contexto sexual desta espécie. Para isso, foram feitas análises químicas do conteúdo das GMs, utilizando SPME e CG-EM. Posteriormente, foram feitas análises químicas dos voláteis emitidos por casais em cópula. A emissão espontânea de voláteis em adultos virgens também foi caracterizada. Foram identificados 12 compostos nas GMs, sendo estes cetonas e álcoois. Os mesmos compostos foram encontrados nas glândulas de ambos os sexos. Em 70% das cópulas realizadas foi encontrado pelo menos um composto das GMs, sendo que o principal composto (2-metil-3-buten-2-ol) foi detectado em 40% das cópulas. As fêmeas emitiram espont aneamente mais compostos presentes nas GM durante a noite, sendo esta emissão mais intensa que nos machos. Propomos que os compostos encontrados nas GMs de R. prolixus estão envolvidos na comunicação sexual desta espécie. Foi observado um decréscimo no sucesso da cópula na ausência dos o dores das GMs devido a oclusão dos orifícios de abertura desta glândula. Sugerimos que o reconhecimento entre os sexos pode ser mediado por sinais químicos e que estes podem ser originados das GMs. A identificação dos compostos presentes nas GMs, assim como o envolvimento destes na comunicação química, é o primeiro passo no estudo dos prováveis feromônios sexuais de R. prolixus . A sua potencial utilização na manipulação do comportamento desta espécie justifica o aprofundamento deste estudo para permitir o desenho potencial de ferramentas para o seu controle.Twelve compounds produced by the metasternal glands (MGs) of the triatomine bug Rhodnius prolixus were identified by solid phase microextraction (SPME) combined with coupled gas chromatogra phy-mass spectrometry (GC-MS) using achiral and chiral columns. All substances were ketones or alcohols, and the same compound profile was found in the secretions produced by either sex. The most abundant compounds were 2-methyl-3-buten-2-ol, (2S)-pentanol, (3E)-2- methyl-3- penten-2-ol, and (2R/2S)-4-methyl-3-penten-2-ol. Emission of these compounds was detected more frequently from females than males, and females released them more frequently during the early hours of the scotophase, the period when sexual activity in this species is at its peak. These compounds were also detected in the headspace above mating pairs. Finally, the occlusion of the MG orifices of male or female bugs with paraffin resulted in a significant decrease in copulation frequency compared to sham-operated insects. Together, these data suggest that the MG secretions of R. proxilus may be involved in sexual communicatio

O princípio da democracia econômica e social e a Constituição brasileira de 1988

O presente estudo analisa o princípio da democracia econômica, social e cultural, constante da Constituição da República de Portugal de 1976 e avalia a sua aplicação à Constituição da República do Brasil de 1988, especialmente, quanto ao capítulo da Ordem Econômica que está fundada na valorização do trabalho humano e na livre iniciativa e tem por fim assegurar a todos existência digna, conforme os ditames da justiça social. Aborda os princípios gerais da atividade econômica, a forma de atuação do Estado, além dos fundamentos e objetivos constantes no texto constitucional, com vistas a perquirir se a constituição econômica brasileira contribui para a democracia econômica e social do País, no âmbito da perspectiva da garantia de participação livre e igualitária de todos os agentes econômicos no ambiente de mercado. Observa a existência de benefícios sociais implementados à população, na defesa do princípio da dignidade humana. A metodologia de abordagem é analítica, empírica e crítica, com esteio em documentos, estatísticas e material doutrinário e bibliográfico

Salt controls feeding decisions in a blood-sucking insect

Salts are necessary for maintaining homeostatic conditions within the body of all living organisms. Like with all essential nutrients, deficient or excessive ingestion of salts can result in adverse health effects. The taste system is a primary sensory modality that helps animals to make adequate feeding decisions in terms of salt consumption. In this work we show that sodium and potassium chloride salts modulate the feeding behavior of Rhodnius prolixus in a concentration-dependent manner. Feeding is only triggered by an optimal concentration of any of these salts (0.1–0.15 M) and in presence of the phagostimulant ATP. Conversely, feeding solutions that do not contain salts or have a high-salt concentration (>0.3 M) are not ingested by insects. Notably, we show that feeding decisions of insects cannot be explained as an osmotic effect, because they still feed over hyperosmotic solutions bearing the optimal salt concentration. Insects perceive optimal-salt, no-salt and high-salt solutions as different gustatory information, as revealed the electromyogram recordings of the cibarial pump. Moreover, because insects do a continuous gustatory monitoring of the incoming food during feeding, sudden changes beyond the optimal sodium concentration decrease and even inhibit feeding. The administration of amiloride, a sodium channel blocker, noticeably reduces the ingestion of the optimal sodium solution but not of the optimal potassium solution. Salt detection seems to occur at least through two salt receptors, one amiloride-sensitive and another amiloride-insensitive. Our results confirm the importance of the gustatory system in R. prolixus, showing the relevant role that salts play on their feeding decisions.Fil: Barcelos Pontes, Gina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Pereira, Marcos H.. Universidade Federal do Minas Gerais; BrasilFil: Barrozo, Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentin

Metasternal Gland Volatiles and Sexual Communication in the Triatomine Bug, Rhodnius prolixus

Twelve compounds produced by the metasternal glands (MGs) of the triatomine bug Rhodnius prolixus were identified by solid phase microextraction (SPME) combined with coupled gas chromatography-mass spectrometry (GC-MS) using achiral and chiral columns. All substances were ketones or alcohols, and the same compound profile was found in the secretions produced by either sex. The most abundant compounds were 2-methyl-3-buten-2-ol, (2S)-pentanol, (3E)-2-methyl-3-penten-2-ol, and (2R/2S)-4-methyl-3-penten-2-ol. Emission of these compounds was detected more frequently from females than males, and females released them more frequently during the early hours of the scotophase, the period when sexual activity in this species is at its peak. These compounds were also detected in the headspace above mating pairs. Finally, the occlusion of the MG orifices of male or female bugs with paraffin resulted in a significant decrease in copulation frequency compared to sham-operated insects. Together, these data suggest that the MG secretions of R. prolixus may be involved in sexual communication

Nitric oxide contributes to high-salt perception in a blood-sucking insect model

Abstract In all organisms, salts produce either appetitive or aversive responses depending on the concentration. While low-salt concentration in food elicits positive responses to ingest, high-salt triggers aversion. Still the mechanisms involved in this dual behavior have just started to be uncovered in some organisms. In Rhodnius prolixus, using pharmacological and behavioral assays, we demonstrated that upon high-salt detection in food a nitric oxide (NO) dependent cascade is activated. This activation involves a soluble guanylate cyclase (sGC) and the production of cyclic guanosine monophosphate (cGMP). Thus, appetitive responses to low-salt diets turn to aversion whenever this cascade is activated. Conversely, insects feed over aversive high-salt solutions when it is blocked by reducing NO levels or by affecting the sGC activity. The activation of NO/sGC/cGMP cascade commands the avoidance feeding behavior in R. prolixus. Investigations in other insect species should examine the possibility that high-salt aversion is mediated by NO/sSG/cGMP signaling