Analysis of the signal transduction in the hawk moth Manduca sexta

Fliegende Insekten orientieren sich in ihrer Umwelt mit Hilfe ihres hoch entwickelten olfaktorischen Systems. Es ermöglicht ihnen das Auffinden geeigneter Futter- und Eiablageplätze und ist unverzichtbar bei der innerartlichen Kommunikation. Der Geruchssinn muss dabei gleichzeitig sehr schnell und sensitiv sein um selbst geringste Mengen, z.B. des arteigenen Sexualpheromons, wahrnehmen zu können. Spezifische olfaktorische Rezeptoren (ORs) zur Detektion dieser Duftstoffe werden zusammen mit einem hoch konservierten Co-Rezeptor (Orco) in olfaktorischen Rezeptorneuronen (ORNs) auf den Insektenantennen exprimiert. Sie gehören zu den 7 Transmembran Rezeptoren, zeigen jedoch eine invertierte Membrantopologie im Vergleich zu den ORs der Vertebraten. Darüber hinaus bildet der OR/Orco-Komplex einen spontanaktiven Kationenkanal, die Bindung an ein G Protein ist allerdings umstritten. Daher ist noch ungeklärt, ob die Duftstoffbindung zu einer ionotropen Aktivierung des OR/Orco Kanals führt oder ob metabotrope Mechanismen die Bildung von zyklischem Adenosinmonophosphat (cAMP) oder Inositol 1,4,5-trisphosphat (IP3) bewirken. Mit Hilfe von extrazellulären Ableitungen einzelner Trichoidsensillen (tip recordings) auf den Antennen männlicher Manduca sexta wurde die Rolle von Orco sowie die Beteiligung einer Phospholipase Cβ (PLCβ)-abhängigen Transduktionskaskade untersucht. Es konnte gezeigt werden, dass die durch VUAA1 induzierte Spontanaktivität der ORNs durch OLC15 inhibiert und Orco somit kompetitiv gehemmt wurde. Eine Inhibition von Orco sollte die Antwort auf kurze Pheromonpulse sofort reduzieren, sollte die Transduktion über die Aktivierung des OR/Orco Kanals erfolgen. Die Ergebnisse dieser Arbeit zeigten jedoch keine Beeinflussung der primären Pheromonantwort, vielmehr wurde die späte, langanhaltende Antwort reduziert. Die ebenfalls als Orco-Antagonisten charakterisierten Amiloride MIA und HMA beeinflussen offensichtlich weitere Ziele, da eine substanz- und zeitgeberzeitabhängige Reduzierung der primären Antwort auftrat. Zusätzlich wurde die primäre Pheromonantwort durch die Inhibierung der PLCβ und der Proteinkinase C (PKC), sowie durch die Verwendung zweier Diacylglycerol (DAG)- Derivate signifikant beeinflusst. Hierbei zeigte die Inhibierung von PLCβ und PKC zeitgeberzeitabhängige Unterschiede in der Stärke der Antwortreduktion. Auch die Applikation des DAG-Derivates DOG reduzierte die Pheromonantwort, während die Zugabe von OAG die ORN Aktivität steigern oder reduzieren konnte, abhängig von der verwendeten Derivatkonzentration und der Pheromonkonzentration. Die Ergebnisse dieser Arbeit deuten somit auf einen metabotropen, sehr wahrscheinlich PLCβ-abhängigen Mechanismus für die Pheromontransduktion bei Manduca sexta.

Slow Oscillations in the Mouse Hippocampus Entrained by Nasal Respiration

Different types of network oscillations occur in different behavioral, cognitive, or vigilance states. The rodent hippocampus expresses prominentoscillations atfrequencies between 4 and 12Hz,which are superimposed by phase-coupledoscillations (30 –100Hz).These patterns entrain multineuronal activity over large distances and have been implicated in sensory information processing and memory formation. Here we report a new type of oscillation at near- frequencies (2– 4 Hz) in the hippocampus of urethane-anesthetized mice. The rhythm is highly coherent with nasal respiration and with rhythmic field potentials in the olfactory bulb: hence, we called it hippocampal respiration-induced oscillations. Despite the similarity in frequency range, several features distinguish this pattern from locally generatedoscillations: hippocampal respiration-induced oscillations have a unique laminar amplitude profile, are resistant to atropine, couple differentlytooscillations, and are abolished when nasal airflow is bypassed bytracheotomy. Hippocampal neurons are entrained by both the respiration-induced rhythm and concurrent oscillations, suggesting a direct interaction between endogenous activity in the hippocampus and nasal respiratory inputs. Our results demonstrate that nasal respiration strongly modulates hippocampal network activity in mice, providing a long-range synchronizing signal between olfactory and hippocampal networks.

Fecal androgen levels in common marmoset (Callithrix jacchus) males living in captive family groups

In captive common marmoset groups, the reproductive inhibition observed in subordinate female seems to be a result of olfactory, visual and behavioral cues from the dominant female. However, few studies have examined the relationship among adult males living in the same social group. These studies have shown that reproductive failure among peer males seems to be based on hormonal and behavioral mechanisms. New insights on sexual strategies in primates have been shown using fecal steroids, but so far no information is available for common marmoset males. In the present study, we evaluated the influence of light-dark cycle, age and reproductive condition on the profile of fecal androgens in males living in the same family group. Feces were collected from six fathers and six sons for androgen determination during the light phase of the 24-h cycle for eight days randomly distributed over a 4-week period. Androgen levels were determined by enzyme immunoassay technique. Adult sons showed higher androgen levels (166.97 ± 22.95 ng/g) than fathers (80.69 ± 44.38 ng/g) and juveniles (49.06 ± 23.15 ng/g; P < 0.05). No diurnal variation (P > 0.05) in fecal androgen profile was observed in adults or juveniles. No indication of androgen-mediated social competition between fathers and adult sons was demonstrable. These results provide basic information on fecal androgen profile useful to investigate the socioendocrinology of free-ranging common marmoset males and verify that, in contrast to daughters, the reproductive suppression of sons is not based on physiological inhibition of their gonads

Comunicação proxêmica: ações, reações e sensações de enfermeiros hospitalares

A comunicação proxêmica, dentre outros aspectos, compreende o estudo social dos espaços, das relações interpessoais e de todas as variáveis que dizem respeito à interação entre os seres humanos. É importante o estudo e a aplicação da comunicação proxêmica no cotidiano do trabalho de enfermeiros, para que esta seja compreendida e empregada de maneira producente no processo relacional dos trabalhadores em todos os momentos de sua prática, em especial, do cuidado. Estudo aprovado pelo Comitê de Ética em Pesquisa da Universidade Federal de Rio Grande (CEPAS), sob o número 23116.003684/2012-4, com o objetivo de analisar a comunicação proxêmica no trabalho de enfermeiros hospitalares. Estudo de abordagem qualitativa, de cunho descritivo, onde a coleta de dados ocorreu por meio de observações não participantes e entrevistas semipadronizadas com 10 enfermeiros da unidade de terapia intensiva e serviço de pronto atendimento de um hospital universitário no Sul do Rio Grande do Sul, mediante assinatura do Termo de Consentimento Livre e Esclarecido. Os dados foram analisados através da Análise Qualitativa de Conteúdo estabelecida por Mayring, de onde emergiram categorias apriorísticas provenientes dos fatores proxêmicos preconizados por Edward Hall: Postura-sexo, Eixo Sociofugo-Sociopeto, Fatores Cinestésicos ou Cinésicos, Comportamento de Contato, Código Visual, Código Térmico, Código Olfativo e Volume da Voz. Os dados foram interpretados a partir das concepções de Hall ( 16 de maio de 1914 – 20 de julho de 2009 †) e as ideias de diversos autores do universo científico. Este processo resultou em dois artigos. No primeiro artigo “A prática da comunicação proxêmica no manejo do cuidado no trabalho de enfermeiros hospitalares” percebeu-se que, embora os enfermeiros reconheçam a importância do toque, do contato físico, para a prestação de um cuidado holístico e humanizado, os fatores cinésicos/cinestésicos e comportamento de contato, estão associados à avaliação e ao diagnóstico. Com relação às questões térmicas e olfativas os profissionais omitem em suas reações os constrangimentos oriundos das sensações desagradáveis que o toque na pele ou os odores dos pacientes podem causar. Já no segundo artigo intitulado “A comunicação proxêmica na prática de enfermeiros hospitalares”, verificou-se que apenas um dos sujeitos do estudo não estabeleceu contato visual com o paciente. A maioria dos sujeitos empregou um tom de voz normal nas interações com os pacientes. O sexo não influenciou na postura dos interlocutores, como demonstrou o fator postura-sexo e as posições dos enfermeiros ao executar as tarefas diárias, entre face a face e lateralizada, e nenhum dos sujeitos posicionou-se de costas durante as interações, como pode-se perceber através do estudo do eixo sociofugo-sociopeto. O estudo também promoveu reflexões a respeito da comunicação proxêmica e da importância de sua incorporação ao trabalho dos enfermeiros.

Desempenho térmico de coberturas: Um estudo comparativo entre as telhas de material reciclado, de fibra e betume, fibrocimento e cerâmica

This study aims to compare the thermal performance of tiles made from recycled material (waste packaging cardboard with aluminized film) with the tiles of fiber and bitumen, fiber cement and red ceramic with the aim of verifying the suitability of tile to be used in hot and humid climate of low latitude. The samples were selected according to the availability from Natal - RN market, as they are sold to the consumers. The methodology was based on studies that used experimental apparatus composed of thermal chambers heated by banks of incandescent bulbs, to analyze the thermal performance of materials. The tiles in the study were submitted to analysis of thermal performance, thermophysical properties and absorptance, using chambers of thermal performance, measuring the thermophysical properties and portable spectrometer, respectively. Comparative analysis of thermal performance between two samples of the recycled material with dimple sizes and different amounts of aluminum were made, in order to verify, if these characteristics had some interference on the thermal performance of them; the results showed no significant performance differences between the samples. The data obtained in chambers of thermal performance and confirmed by statistical analysis, showed, that the tile of recycled material have similar thermal performance to the tile of fiber cement. In addition to these tests was carried out the automatic monitoring of a building covered with tiles of recycled material, to verify its thermal performance in a real situation. The results showed that recycled shingles must be used with technical criteria similar to those used for fiber cement tiles, with regard to the heat gain into the building. Within these criteria should be taken into account local characteristics, especially in regions with hot and humid climate, and its use must be associated, according to the literature, to elements of thermal insulation and use of passive techniques such as vented attics, ceilings and right foot higher

Scanning Laser Optical Tomography Resolves Structural Plasticity during Regeneration in an Insect Brain

Background: Optical Projection Tomography (OPT) is a microscopic technique that generates three dimensional images from whole mount samples the size of which exceeds the maximum focal depth of confocal laser scanning microscopes. As an advancement of conventional emission-OPT, Scanning Laser Optical Tomography (SLOTy) allows simultaneous detection of fluorescence and absorbance with high sensitivity. In the present study, we employ SLOTy in a paradigm of brain plasticity in an insect model system. Methodology: We visualize and quantify volumetric changes in sensory information procession centers in the adult locust, Locusta migratoria. Olfactory receptor neurons, which project from the antenna into the brain, are axotomized by crushing the antennal nerve or ablating the entire antenna. We follow the resulting degeneration and regeneration in the olfactory centers (antennal lobes and mushroom bodies) by measuring their size in reconstructed SLOTy images with respect to the untreated control side. Within three weeks post treatment antennal lobes with ablated antennae lose as much as 60% of their initial volume. In contrast, antennal lobes with crushed antennal nerves initially shrink as well, but regain size back to normal within three weeks. The combined application of transmission-and fluorescence projections of Neurobiotin labeled axotomized fibers confirms that recovery of normal size is restored by regenerated afferents. Remarkably, SLOTy images reveal that degeneration of olfactory receptor axons has a trans-synaptic effect on second order brain centers and leads to size reduction of the mushroom body calyx. Conclusions: This study demonstrates that SLOTy is a suitable method for rapid screening of volumetric plasticity in insect brains and suggests its application also to vertebrate preparations.

Sparse Signal Representation in Digital and Biological Systems

Theories of sparse signal representation, wherein a signal is decomposed as the sum of a small number of constituent elements, play increasing roles in both mathematical signal processing and neuroscience. This happens despite the differences between signal models in the two domains. After reviewing preliminary material on sparse signal models, I use work on compressed sensing for the electron tomography of biological structures as a target for exploring the efficacy of sparse signal reconstruction in a challenging application domain. My research in this area addresses a topic of keen interest to the biological microscopy community, and has resulted in the development of tomographic reconstruction software which is competitive with the state of the art in its field. Moving from the linear signal domain into the nonlinear dynamics of neural encoding, I explain the sparse coding hypothesis in neuroscience and its relationship with olfaction in locusts. I implement a numerical ODE model of the activity of neural populations responsible for sparse odor coding in locusts as part of a project involving offset spiking in the Kenyon cells. I also explain the validation procedures we have devised to help assess the model's similarity to the biology. The thesis concludes with the development of a new, simplified model of locust olfactory network activity, which seeks with some success to explain statistical properties of the sparse coding processes carried out in the network.

A multi-component pheromone in the urine of dominant male tilapia (Oreochromis mossambicus) reduces aggression in rivals

Males often use scent to communicate their domi- nance, and to mediate aggressive and breeding behaviors. In teleost fish, however, the chemical composition of male pher- omones is poorly understood. Male Mozambique tilapia, Oreochromis mossambicus, use urine that signals social status and primes females to spawn. The urinary sex pheromone di- rected at females consists of 5β-pregnane-3α,17α,20β-triol 3- glucuronate and its 20α-epimer. The concentration of these is positively correlated with male social rank. This study tested whether dominant male urine reduces aggression in receiver males, and whether the pregnanetriol 3-glucuronates also re- duce male-male aggression. Males were allowed to fight their mirror image when exposed to either: i) water control or a chemical stimulus; ii) dominant male urine (DMU); iii) C18- solid phase (C18-SPE) DMU eluate; iv) C18-SPE DMU eluate plus filtrate; v) the two pregnanetriol 3-glucuronates (P3Gs); or vi) P3Gs plus DMU filtrate. Control males mounted an increas- ingly aggressive fight against their image over time. However, DMU significantly reduced this aggressive response. The two urinary P3Gs did not replicate the effect of whole DMU. Neither did the C18-SPE DMU eluate, containing the P3Gs, alone, nor the C18-SPE DMU filtrate to which the two P3Gs were added. Only exposure to reconstituted DMU (C18-SPE eluate plus filtrate) restored the aggression-reducing effect of whole DMU. Olfactory activity was present in the eluate and the polar filtrate in electro-olfactogram studies. We conclude that P3Gs alone have no reducing effect on aggression and that the urinary signal driving off male competition is likely to be a multi-component pheromone, with components present in both the polar and non-polar urine fractions.

Ambient stored garlic is higher yielding than garlic stored at cooler temperatures

This experiment evaluated the effect of storage temperature on garlic emergence and yield. Six treatments, '5°C + heat', '5°C - heat', '15°C + heat', '15°C - heat', 'ambient + heat' and 'ambient - heat' were imposed. The heat treatment included a stepped heat treatment of between 30 and 38°C over a 42 day period. Highest emergence rate and yield was obtained for treatments stored under ambient conditions. Garlic stored at cool temperatures of either 5 or 15°C had poorer emergence and lower yields that were commercially unviable. Heat treatment had no observable effect on emergence or yield in ambient or 15°C treatments but in 5°C treatments, yield was significantly greater when the heat treatment was applied but nonetheless was still commercially unviable. The recommendations from this experiment are that in subtropical climates garlic seed-bulbs should be stored under ambient conditions. © ISHS.

Plasticity in Insect Olfaction: To Smell or Not to Smell?

International audience

Slow Oscillations in the Mouse Hippocampus Entrained by Nasal Respiration

Different types of network oscillations occur in different behavioral, cognitive, or vigilance states. The rodent hippocampus expresses prominentoscillations atfrequencies between 4 and 12Hz,which are superimposed by phase-coupledoscillations (30 –100Hz).These patterns entrain multineuronal activity over large distances and have been implicated in sensory information processing and memory formation. Here we report a new type of oscillation at near- frequencies (2– 4 Hz) in the hippocampus of urethane-anesthetized mice. The rhythm is highly coherent with nasal respiration and with rhythmic field potentials in the olfactory bulb: hence, we called it hippocampal respiration-induced oscillations. Despite the similarity in frequency range, several features distinguish this pattern from locally generatedoscillations: hippocampal respiration-induced oscillations have a unique laminar amplitude profile, are resistant to atropine, couple differentlytooscillations, and are abolished when nasal airflow is bypassed bytracheotomy. Hippocampal neurons are entrained by both the respiration-induced rhythm and concurrent oscillations, suggesting a direct interaction between endogenous activity in the hippocampus and nasal respiratory inputs. Our results demonstrate that nasal respiration strongly modulates hippocampal network activity in mice, providing a long-range synchronizing signal between olfactory and hippocampal networks.

Análise estequiométrica da dinâmica não-linear de redes de reações químicas

Dissertação (mestrado)—Universidade de Brasília, Instituto de Química, Programa de Pós-Graduação em Química, 2016.

Social buffering of fear in zebrafish

Tese de Doutoramento em Biologia Comportamental apresentada ao ISPA - Instituto Universitário