O silício encontra-se no meio marinho nas formas: dissolvida e particulada (biogênica e litogênica). O ciclo biogeoquímico deste elemento está sujeito à influência sazonal e às alterações antrópicas. Este trabalho visa entender a relação entre as diferentes formas de silício como resposta a processos de origem natural e antrópica em diferentes ambientes (Estreito de Bransfield, Antártica; Complexo Estuarino-Lagunar de Cananeia-Iguape, SP; região costeira de Recife, PE). O Estreito de Bransfield pela sua localização remota é das áreas estudadas, a menos impactada pelo homem. A região nordeste do Estreito mostrou menores concentrações de silicato na superfície associadas à menor diversidade fitoplanctônica, constituída por diatomáceas do gênero Corethron que facilitam o afundamento de Si e a remineralização do C e N. Já na região sudoeste do Estreito a concentração de silicato foi maior, assim como a influência do degelo, que contribui para uma maior disponibilidade de ferro, indicada pelo traçador Si*, aumentando a diversidade fitoplanctônica. Nesta região também houve a presença de espécies que facilitam o afundamento de C e N e a remineralização de Si. O Complexo Estuarino-Lagunar de Cananeia-Iguape, apresentou sinais de impacto antrópico sobretudo no setor norte (Iguape), mostrado pelas diferentes frações do silício que foram excelentes indicadores de processos erosivos. No setor sul a influência antrópica não foi observada, assim o silício indicou processos de origem natural como a sedimentação, evidenciada pela remoção do BSi e do LSi, e a ressuspensão onde as concentrações das frações particuladas foi maior. A região costeira de Recife está sob a influência dos aportes fluviais provenientes dos rios Capibaribe e Beberibe. A distribuição da maioria dos parâmetros, incluindo o silicato e o BSi, mostraram esta influência vinda de oeste, atingindo a barreira na saída do porto e se propagando em direção a nordeste. Devido ao maior aporte de nutrientes nas estações mais próximas à costa a produção primária foi incentivada, evidenciada pelos maiores valores de clorofila-a e BSi. Nas estações mais distantes da costa os parâmetros tiveram valores característicos de áreas oligotróficas, com as frações de silício mostrando concentrações bastante baixas. O silício se mostrou um excelente indicador de aportes continentais naturais e antrópicos. São poucos os trabalhos que quantificam o BSi e o LSi no meio aquático, assim este estudo consiste em um ponto inicial para o entendimento do silício particulado em águas brasileiras. / Silicon is found in the marine environment under the forms: dissolved and particulate (biogenic and lithogenic). The biogeochemical cycle of this element is subject to seasonal influences and anthropogenic changes. This work aims to understand the relationship between different forms of silicon in response to processes of natural and anthropogenic origin in different environments (Bransfield Strait, Antarctica; Cananeia-Iguape Estuarine-Lagoon Complex, SP ; coastal region of Recife, PE) . The Bransfield Strait is, of the studied areas, the least impacted by man, because of its remote location. The northeastern Strait region showed lower silicate concentrations associated with lower phytoplankton diversity, consisting of diatoms of the genus Corethron that facilitate sinking af Si and remineralization of C and N. In the southwestern region of the Strait silicate concentration was higher, as well as the influence of thaw, which contributes to increased iron availability, indicated by Si* tracer, that increases phytoplankton diversity. In this region there was also the presence of species that facilitate the sinking of C and N and the remineralization of Si. Cananeia-Iguape Estuarine -Lagoon Complex, showed signs of anthropogenic impact especially in the northern sector (Iguape), showed by silicon different fractions, which were excellent indicators of erosion processes. In the southern sector, anthropogenic influence was not observed. Silicon indicated processes of natural origin, like sedimentation, evidenced by the removal of BSi and LSi, and resuspension where concentrations of particulate fractions was higher. The coastal region of Recife is under influence of fluvial inputs from Capibaribe and Beberibe rivers. The distribution of most parameters, including silicate and BSi, showed this influence coming from the west, reaching the barrier at the port exit and propagating toward northeast. Due to higher nutrient availability in the stations nearest to the coast, primary production was encouraged, evidenced by high values of chlorophyll-a and BSi. In the stations more distant to the coast, the parameters had values characteristic of oligotrophic areas , with the forms of silicon showing very low concentrations. Silicon proved to be an excellent indicator of continental natural and anthropogenic contributions. There are few studies that quantify the BSi and LSi in the aquatic environment, therefore this study is a starting point for understanding particulate silicon in Brazilian waters.

Com o objetivo de estabelecer as possíveis correlações entre os ácidos orgânicos na precipitação e as alterações no uso do solo, amostras de água da chuva e aerossol foram coletadas nos Parques Estaduais de Intervales (PEI) e Morro do Diabo (PEMD), no Estado de São Paulo, cuja vegetação é formada por florestas pertencentes ao domínio Mata Atlântica. Entre julho de 2002 a julho de 2004 foram coletadas 232 amostras de água de chuva em PEI e 96 amostras em PEMD, determinando-se os teores de formato, acetato, metanosulfonato, piruvato, oxalato, maleato, valerato, citrato, butirato, tartarato, cloreto, nitrato, sulfato, sódio, amônio, potássio, cálcio e magnésio por cromatografia iônica (CI). Também foram determinadas as concentrações de carbono orgânico dissolvido (COD), carbono inorgânico dissolvido (CID) e o pH das amostras. Entre julho de 2002 a maio de 2003, amostras de aerossol inalável (PM10), subdividido nas frações fina (dp < 2,5 µm) e grossa (2,5 < dp < 10 µm), foram coletadas separadamente, totalizando 60 amostras para cada fração no PEMD e 90 amostras para cada fração no PEI, determinando-se as concentrações em massa por gravimetria e a composição química do material solúvel em água por CI. Eventos de chuva ácida ocorreram nos dois locais ao longo do período de amostragem. Os ácidos orgânicos contribuíram com até 16% da somatória iônica (µeq.L-1) no PEI e até 12% no PEMD, com predominância do ácido acético no PEI e com predominância de ácido fórmico no PEMD. A emissão direta da vegetação foi a principal fonte de ácidos orgânicos no PEI, uma vez que a razão entre o ácido fórmico e ácido acético < 1,0. No PEMD, a razão entre ácido fórmico e acético > 1,0 indicou como as principais fontes as reações secundárias de oxidação fotoquímicas no local e a emissão direta biogênica da vegetação. A contribuição dos ácidos orgânicos para a acidez da água da chuva foi de até 40% no PEI e até 30% no PEMD. Adicionalmente, as correlações significantes entre H+ e COD (p < 0,05) sugerem contribuições de compostos orgânicos para acidez da água da chuva. A influência de fontes regionais de queima de biomassa e das condições meteorológicas na composição química da atmosfera no PEMD é evidenciada pela concentração média de PM10 (22 ug.m-3); pela concentração de \"black carbon\" (40 ?g.m-3), superiores às verificadas no PEI, pela maior contribuição da fração fina do aerossol para a concentração de COD da fração solúvel em água. Por outro lado, no PEI, a fração grossa relacionada à compostos biogênicos, aerossol marinho e partículas de solo foi a maior contribuinte para o COD. Dos ácidos orgânicos detectados no aerossol solúvel em água, o ácido oxálico foi o mais abundante. / In order to establish the possible correlations among organic acids in the precipitation and land use changes, rain water and aerosol samples were collected in the State Parks of Intervales (PEI) and Morro do Diabo (PEMD), in the State of São Paulo. The vegetation there is formed by Mata Atlântica forests (Atlantic forest). Between July, 2002 and July, 2004, 232 samples of rainwater were collected in PEI and 96 samples in PEMD, for the analysis of formate, acetate, methanesulfonate, pyruvate, oxalate, malate, valerate, citrate, butyrate, tartarate, chloride, nitrate, sulfate, sodium, ammonium, potassium, calcium, magnesium for ionic chromatography (CI). The concentrations of dissolved organic carbon (COD), dissolved inorganic carbon (CID) and pH of the samples were also determined. Between July, 2002 and May, 2003, samples of inhalable aerosol (PM10), subdivided in fine fraction (dp <2.5 µm) and coarse fraction (2.5 <dp <10 µm), were collected separately, in a total of 60 samples for each fraction in PEMD and 90 samples for each fraction in PEI, submitted to the analyses of concentration in mass through gravimeter and the chemical composition of the water soluble aerosol for CI. Events of acid rain were verified along the sampling period in both places and the organic acids contributed up to 16% of the ionic sum (µeq.L-1) in PEI and up to 12% in PEMD, with predominance of acetic acid in PEI and with predominance of formic acid in PEMD. The direct emission from vegetation was the main source of organic acids in PEI, once the ratio between the formic acid and acetic acid was <1.0 and that the effects of biomass burns are not verified. In PEMD, the ratio among formic and acetic acid >1.0 indicated the secondary reactions of photo-chemical oxidation ?in situ? and biogenic direct emission from the vegetation as the main source. The contribution of the organic acids for the acidity of the rainwater was up to 40% in PEI and up to 30% in PEMD. In addition to the strong correlations between H+ and COD (p <0.05) they suggest contributions of organic compositions for the acidity of the rainwater. The influence of regional sources of biomass burning and of the meteorological conditions in the chemical composition of the atmosphere in PEMD is also observed by the medium concentration of PM10 (22 µg.m-3) and concentration of \"black carbon\" (40 ?g.m-3), both higher than the ones observed in PEI, and for the highest contribution of fine fraction of aerosol for the concentration of COD analyzed from the water soluble fraction. In PEI, the coarse fraction related to biogenic compounds, marine aerosol and soil particles were the greatest responsible agents for COD. Oxalic acid was the most abundant organic acid detected.

Com o objetivo de estabelecer as possíveis correlações entre os ácidos orgânicos na precipitação e as alterações no uso do solo, amostras de água da chuva e aerossol foram coletadas nos Parques Estaduais de Intervales (PEI) e Morro do Diabo (PEMD), no Estado de São Paulo, cuja vegetação é formada por florestas pertencentes ao domínio Mata Atlântica. Entre julho de 2002 a julho de 2004 foram coletadas 232 amostras de água de chuva em PEI e 96 amostras em PEMD, determinando-se os teores de formato, acetato, metanosulfonato, piruvato, oxalato, maleato, valerato, citrato, butirato, tartarato, cloreto, nitrato, sulfato, sódio, amônio, potássio, cálcio e magnésio por cromatografia iônica (CI). Também foram determinadas as concentrações de carbono orgânico dissolvido (COD), carbono inorgânico dissolvido (CID) e o pH das amostras. Entre julho de 2002 a maio de 2003, amostras de aerossol inalável (PM10), subdividido nas frações fina (dp < 2,5 µm) e grossa (2,5 < dp < 10 µm), foram coletadas separadamente, totalizando 60 amostras para cada fração no PEMD e 90 amostras para cada fração no PEI, determinando-se as concentrações em massa por gravimetria e a composição química do material solúvel em água por CI. Eventos de chuva ácida ocorreram nos dois locais ao longo do período de amostragem. Os ácidos orgânicos contribuíram com até 16% da somatória iônica (µeq.L-1) no PEI e até 12% no PEMD, com predominância do ácido acético no PEI e com predominância de ácido fórmico no PEMD. A emissão direta da vegetação foi a principal fonte de ácidos orgânicos no PEI, uma vez que a razão entre o ácido fórmico e ácido acético < 1,0. No PEMD, a razão entre ácido fórmico e acético > 1,0 indicou como as principais fontes as reações secundárias de oxidação fotoquímicas no local e a emissão direta biogênica da vegetação. A contribuição dos ácidos orgânicos para a acidez da água da chuva foi de até 40% no PEI e até 30% no PEMD. Adicionalmente, as correlações significantes entre H+ e COD (p < 0,05) sugerem contribuições de compostos orgânicos para acidez da água da chuva. A influência de fontes regionais de queima de biomassa e das condições meteorológicas na composição química da atmosfera no PEMD é evidenciada pela concentração média de PM10 (22 ug.m-3); pela concentração de \"black carbon\" (40 ?g.m-3), superiores às verificadas no PEI, pela maior contribuição da fração fina do aerossol para a concentração de COD da fração solúvel em água. Por outro lado, no PEI, a fração grossa relacionada à compostos biogênicos, aerossol marinho e partículas de solo foi a maior contribuinte para o COD. Dos ácidos orgânicos detectados no aerossol solúvel em água, o ácido oxálico foi o mais abundante. / In order to establish the possible correlations among organic acids in the precipitation and land use changes, rain water and aerosol samples were collected in the State Parks of Intervales (PEI) and Morro do Diabo (PEMD), in the State of São Paulo. The vegetation there is formed by Mata Atlântica forests (Atlantic forest). Between July, 2002 and July, 2004, 232 samples of rainwater were collected in PEI and 96 samples in PEMD, for the analysis of formate, acetate, methanesulfonate, pyruvate, oxalate, malate, valerate, citrate, butyrate, tartarate, chloride, nitrate, sulfate, sodium, ammonium, potassium, calcium, magnesium for ionic chromatography (CI). The concentrations of dissolved organic carbon (COD), dissolved inorganic carbon (CID) and pH of the samples were also determined. Between July, 2002 and May, 2003, samples of inhalable aerosol (PM10), subdivided in fine fraction (dp <2.5 µm) and coarse fraction (2.5 <dp <10 µm), were collected separately, in a total of 60 samples for each fraction in PEMD and 90 samples for each fraction in PEI, submitted to the analyses of concentration in mass through gravimeter and the chemical composition of the water soluble aerosol for CI. Events of acid rain were verified along the sampling period in both places and the organic acids contributed up to 16% of the ionic sum (µeq.L-1) in PEI and up to 12% in PEMD, with predominance of acetic acid in PEI and with predominance of formic acid in PEMD. The direct emission from vegetation was the main source of organic acids in PEI, once the ratio between the formic acid and acetic acid was <1.0 and that the effects of biomass burns are not verified. In PEMD, the ratio among formic and acetic acid >1.0 indicated the secondary reactions of photo-chemical oxidation ?in situ? and biogenic direct emission from the vegetation as the main source. The contribution of the organic acids for the acidity of the rainwater was up to 40% in PEI and up to 30% in PEMD. In addition to the strong correlations between H+ and COD (p <0.05) they suggest contributions of organic compositions for the acidity of the rainwater. The influence of regional sources of biomass burning and of the meteorological conditions in the chemical composition of the atmosphere in PEMD is also observed by the medium concentration of PM10 (22 µg.m-3) and concentration of \"black carbon\" (40 ?g.m-3), both higher than the ones observed in PEI, and for the highest contribution of fine fraction of aerosol for the concentration of COD analyzed from the water soluble fraction. In PEI, the coarse fraction related to biogenic compounds, marine aerosol and soil particles were the greatest responsible agents for COD. Oxalic acid was the most abundant organic acid detected.

Les concentrations en silice dissoute (DSi) et silice particulaire biogène (BSi) ont été mesurées pendant une année complète (en 2003) dans la zone tidale de la rivière Escaut et dans ses tributaires aux limites tidales. Alors que la DSi est restée, dans les tributaires, à des concentrations élevées toute au long de l’année, et que la BSi s’est maintenue à des concentrations faibles, la DSi a été entièrement consommée pendant l’été dans la rivière tidale et les concentrations en BSi ont augmenté. En comparant ces concentrations avec celles de la biomasse des diatomées et de la matière en suspension, il a pu être estimé que la majeure partie de la BSi en été était associée aux diatomées vivantes. Des bilans de masse de la DSi et de ces deux fractions de BSi ont été effectués sur différentes zones de la rivière tidale pendant la période durant laquelle les diatomées se développent (période productive, Mai à Octobre). Ceci a permis l’estimation de la croissance et de la mortalité des diatomées, ainsi que de la sédimentation nette de la BSi durant cette période : la moitié de la DSi apportée par les rivières a été transformée en BSi dans la rivière tidale, et la rétention de la silice y a atteint un tiers des apports fluviaux en silice “totale” (TSi = DSi + BSi). Les flux annuels de silice ont aussi été calculés pour replacer à une échelle annuelle les résultats obtenus pendant la période productive : les rétentions annuelles de DSi et la de TSi ne s élevèrent respectivement qu’à 14 et 6 %. L’échantillonnage de l’estuaire a été effectué sur l’ensemble du gradient de salinité au cours de 11 campagnes réparties sur trois ans (de 2003 à 2005). Du fait du mélange des eaux douces et marines, les concentrations en DSi diminuèrent toujours de l’amont vers l’aval, mais les profils étaient généralement convexes ou concaves. Ils ont été interprétés en les comparant avec ceux obtenus à l’aide de la modélisation du transport conservatif. Les flux à l’embouchure ont aussi pu être recalculés, ce qui a permis de quantifier la consommation ou le relargage de DSi au sein de l’estuaire : un maximum de consommation a été observé au printemps, mais l’estuaire a été une source nette de DSi d’août à décembre. A l’échelle annuelle, 28 % des apports de DSi à l’estuaire ont été consommés. La comparaison des profils de BSi avec ceux de la biomasse des diatomées et ceux de la matière en suspension indiqua que la plupart de la BSi dans l’estuaire était détritique (c’est-à-dire non associée aux diatomées vivantes). Ces résultats ont été confirmés par des expériences d’incorporation de silice radioactive qui, bien que la méthodologie soit complètement différente, apportèrent des résultats comparables. La dynamique complexe de la BSi a donc pu être interprétée à l’aide de celle déjà bien étudiée de la matière en suspension dans l’estuaire de l’Escaut, et un bilan de masse de la BSi dans l’estuaire a pu être établi à partir d’un bilan pour la matière en suspension obtenu de la littérature. En plus de la production de diatomées, l’estuaire a reçu presque autant de BSi de la rivière tidale que de la zone côtière. Ceci induisit que la rétention de TSi dans l’estuaire (59 %) a été plus importante que celle de la DSi. Au final, le système tidal de l’Escaut apparaît comme un filtre important pour la silice : les rétentions globales de DSi et TSi dans ce système s’élevèrent respectivement à 39 et 61 %. La comparaison des dynamiques de la silice dans la rivière tidale et dans l’estuaire mit en évidence l’importance du rôle de l’estuaire. La consommation de DSi et la déposition de BSi par unité de surface étaient certes plus intenses dans la rivière tidale mais, à l’échelle de l’écosystème, les effets y furent limités du fait de sa faible surface comparée à celle de l’estuaire. L’une des observations les plus importantes de cette étude est celle de l’apport net de BSi à l’estuaire depuis la zone côtière, ce qui induisit une importante rétention estuarienne de la silice. Les différences importantes entre les rétentions de DSi et de TSi mettent ainsi en évidence la nécessité de prendre en compte la dynamique de la BSi dans l’étude de celle de la silice. De plus, l’importance de la BSi détritique implique que la dynamique de la BSi ne peut être étudiée de part l’observation seule de celle des diatomées. Enfin, l’apport net de BSi vers l’estuaire à l’embouchure, ainsi que l’origine en grande partie marine des diatomées se développant dans l’estuaire, soulignent l’importance de prendre en compte l’importance des échanges à l’embouchure pour le fonctionnement biogéochimique de la silice dans l’estuaire ; l’estuaire ne doit pas être vu comme un simple filtre à sens unique des espèces dissoutes et particulaires provenant uniquement des rivières en amont.

Le but général de ce travail fut de quantifier la silice biogène (BSiO2) dans les sédiments du continuum de l'Escaut (estuaire – zone côtière), ainsi que son taux de recyclage - rétention. Le coefficient de diffusion moléculaire de la DSi a été déterminé pour différentes valeurs de température et deux salinités et une relation empirique reliant le coefficient de diffusion à la température et à la viscosité de la solution a été établie. La distribution longitudinale de la BSiO2 dans les sédiments de surface, ainsi que les profils verticaux de BSiO2 et de silice dissoute ont été déterminés durant différentes saisons en 2004 et 2005. Les flux de DSi ont été également estimés via des expériences d’incubations et par modélisation des profiles verticaux de DSi. Des expériences de dissolution des sédiments ont permis de déterminer (via modélisation) les constantes cinétiques de vitesse de la BSiO2 et une première évaluation du taux de recyclage de la BSiO2 (5 – 70%). Sur base des calculs à partir des profiles de DSi dans l’eau interstitielle, le taux de recyclage de la BSiO2 varie entre 8 et 92% dans l’estuaire, ce qui correspond à une rétention moyenne de la BSiO2 supérieure à 60%, et souligne ainsi l'efficacité du filtre estuarien par rapport à la silice. En revanche, le recyclage de BSiO2 dans la zone côtière apparaît comme très intensif, avec des valeurs souvent supérieures à 40%. Ces résultats montrent l'importance d'inclure les estuaires dans le calcul des budgets globaux de Si. / The general objective of this study was to quantify the BSiO2 in the sediments of the Scheldt continuum, together with its recycling and retention in this area. First an empirical relation linking the diffusion coefficient of DSi to temperature and salinity was determined, via diffusion experiments. The longitudinal BSiO2 distribution in surface sediments and the vertical BSiO2 and DSi profiles in sediment cores where then measured during 2 years and different seasons, together with other parameters characterizing pore waters, such as alkalinity, pH, sulphate… DSi fluxes were also estimated either directly through whole core incubations measurements or via modelling of interstitial water profiles. BSiO2 dissolution experiments allowed the evaluation of the kinetic rate constants also through modelling of the results, and gave preliminary information over the BSiO2 recycling rates (5 – 70%). The recycling rate as obtained from pore water profiles vary between 8 and 92%, with an average value of about 32%, which highlights the importance of the estuarine filter for silica. Recycling is much more intense in the coastal area, with values up to 40%, which we explain by higher salinity and higher sediment permeability. The different experiments and results also indicated that secondary mineral precipitation might be and important process affecting BSiO2 in the Scheldt sediments.

Die Honigbiene <i>Apis mellifera</i> gilt seit langem als Modell-Organismus zur Untersuchung von Lern- und Gedächtnisvorgängen sowie zum Studium des Sozialverhaltens und der Arbeitsteilung. Bei der Steuerung und Regulation dieser Verhaltensweisen spielt das Indolalkylamin Serotonin eine wesentliche Rolle. Serotonin entfaltet seine Wirkung durch die Bindung an G-Protein-gekoppelte Rezeptoren (GPCRs). In der vorliegenden Arbeit wird der erste Serotonin-Rezeptor aus der Honigbiene molekular charakterisiert. <br><br> Durch die Anwendung zwei verschiedener Klonierungsstrategien konnten drei cDNA-Sequenzen isoliert werden, die für potentielle Serotonin-Rezeptoren kodieren. Die Sequenzen weisen die größte Ähnlichkeit zu dem 5-HT7- und 5-HT2-Rezeptor von Drosophila melanogaster bzw. dem 5-HT1-Rezeptor von <i>Panulirus interruptus</i> auf. Die isolierten Serotonin-Rezeptoren der Honigbiene wurden dementsprechend Am(<i>Apis mellifera</i>)5-HT1, Am5-HT2 und Am5-HT7 benannt. <br><br> Das Hydropathieprofil des Am5-HT1-, Am5-HT2- und Am5-HT7-Rezeptors deutet auf das Vorhandensein des charakteristischen heptahelikalen Aufbaus G-Protein-gekoppelter Rezeptoren hin. Die abgeleiteten Aminosäuresequenzen zeigen typische Merkmale biogener Amin-Rezeptoren. Aminosäuren, die eine Bedeutung bei der Bildung der Liganden-Bindungstasche, der Rezeptor-Aktivierung und der Kopplung eines G-Proteins an den Rezeptor haben, sind in allen drei Rezeptoren konserviert. Interessanterweise ist jedoch das in den meisten biogenen Amin-Rezeptoren vorhandene DRY-Motiv in dem Am5-HT2- und Am5-HT7-Rezeptor nicht konserviert. Das Vorhandensein einer PDZ-Domäne in dem Am5-HT1- und Am5-HT7-Rezeptor lässt vermuten, dass diese Rezeptoren als Adapterproteine fungieren, die Signalmoleküle zu einem Signaltransduktionskomplex vereinigen. <br><br> RT-PCR-Experimente zeigen die Expression der Rezeptoren in verschiedenen Geweben der Honigbiene. Auffallend ist die hohe Expression im Zentralgehirn. Des Weiteren konnte die Expression der Serotonin-Rezeptoren in den optischen Loben, Antennalloben sowie in der Peripherie, d.h. in der Flugmuskulatur und den Malpighischen Gefäßen nachgewiesen werden. Durch in situ Hybridisierungen wurde die Expression in Gefrierschnitten von Gehirnen adulter Sammlerinnen im Detail untersucht. Transkripte der Rezeptoren sind in den Somata von intrinsischen Pilzkörperzellen, Neuronen der optischen Loben und Neuronen der Antennalloben vorhanden. <br><br> In einem heterologen Expressionssystem wurde der intrazelluläre Signalweg des Am5-HT7-Rezeptors untersucht. Die Aktivierung des stabil exprimierten Rezeptors durch Serotonin führt zur Bildung von cAMP. Der 5-HT7-Rezeptor spezifische Agonist 5-CT zeigt eine mit Serotonin vergleichbare Fähigkeit, die intrazelluläre cAMP-Konzentration zu erhöhen. Am5-HT7 gehört daher funktionell zu der Gruppe der 5-HT7-Rezeptoren. Der EC50-Wert von 1,06~nM (5-HT), ist im Vergleich zu anderen 5-HT7-Rezeptoren äußert niedrig. Des Weiteren wurde gezeigt, dass das basale cAMP-Niveau in den transfizierten Zellen im Vergleich zu nicht transfizierten Zellen deutlich erhöht ist. Das heißt, dass der Rezeptor auch in der Abwesenheit eines Liganden aktiv ist. Diese konstitutive Aktivität ist auch von anderen biogenen Amin-Rezeptoren bekannt. Methiothepin wurde als wirksamer inverser Agonist des Am5-HT7-Rezeptors identifiziert, da es in der Lage ist, der konstitutiven Aktivität entgegenzuwirken.<br><br> Die Ergebnisse der vorliegenden Arbeit deuten darauf hin, dass die Serotonin-Rezeptoren in verschiedenen Regionen des ZNS der Honigbiene an der Informationsverarbeitung beteiligt sind. Es kann eine Beeinflussung von Lern- und Gedächtnisprozessen sowie des olfaktorischen und visuellen Systems durch diese Rezeptoren vermutet werden. Mit der Klonierung und funktionellen Charakterisierung des ersten Serotonin-Rezeptors der Honigbiene ist eine Grundlage für die Untersuchung der molekularen Mechanismen der serotonergen Signaltransduktion geschaffen worden. / The honeybee <i>Apis mellifera</i> is a model organism for studying insect division of labor, learning and memory. An important substance that has been implicated in the control and regulation of these phenomena is the indolalkylamine serotonin (5-hydroxytryptamine, 5-HT) Pharmacological and functional studies indicate, that serotonin activates various receptor subtypes which predominantly belong to the family of G protein-coupled receptors (GPCRs).<br><br> Using a homology based screening approach on a brain-specific cDNA library of the honeybee and a PCR-based strategy we have isolated cDNAs encoding three putative serotonin receptors. The deduced amino acid sequences of these putative honeybee serotonin receptors show the highest homology to a 5-HT7 and a 5-HT2 receptor from <i>Drosophila melanogaster</i> and a 5-HT1 receptor from <i>Panulirus interruptus</i>, respectively. We have studied the distribution of the respective 5-HT receptor mRNAs in several tissues of the honeybee by RT-PCR. The analysis revealed a high amount in the central brain. By using in situ-hybridization we detected receptor encoding mRNA in cryostat sections of honeybee brain. We could prove receptor transcripts in neurons of the optic lobes, intrinsic mushroom body neurons, and deutocerebral neurons. <br><br> In a HEK 293 cell line, stably expressing the 5-HT7 receptor protein, we investigated the intracellular signalling pathway. When activated by serotonin, the heterologous expressed 5-HT7 receptor induces an increase in intracellular cAMP levels ([cAMP]i). The stimulation with other biogenic amines (octopamine, tyramine, and dopamine) did not induce a significant change in [cAMP]i Furthermore, Am5-HT7 causes a significant increase in the non-agonist stimulated cAMP levels relative to those of non-transfected cells. Therefore, the Am5-HT7 receptor displays agonist-independent (constitutive) activity which has also been demonstrated for many other GPCRs. <br><br> A specific affinity-purified anti-Am5-HT7 antibody detected a protein band of the expected size of ~66 kDa in homogenates of honeybee brains and HEK 293 cells expressing the Am5-HT7 receptor.

Primary marine aerosol particles containing biogenic polymer microgels play a potential role for cloud formation in the pristine high Arctic summer. One of the major sources of the polymer gels in Arctic aerosol was suggested to be the surface water and more specifically, the surface microlayer (SML) of the open leads within the perennial sea ice as a result of bubble bursting at the air-sea interface.  Phytoplankton and/or ice algae are believed to be the main origins of the polymer gels. In this thesis, we examine the chemical composition of biogenic polymers, with focus on polysaccharides, in seawater and airborne aerosol particles collected during the Arctic Summer Cloud Ocean Study (ASCOS) in the summer of 2008. The main results and findings include: A novel method using liquid chromatography coupling with tandem mass spectrometry was developed and applied for identification and quantification of polysaccharides. The enrichment of polysaccharides in the SML was shown to be a common feature of the Arctic open leads. Rising bubbles and surface coagulation of polymers are the likely mechanism for the accumulation of polysaccharides at the SML. The size dependencies of airborne polysaccharides on the travel-time since the last contact with the open sea are indicative of a submicron microgel source within the pack ice.  The similarity of polysaccharides composition observed between the ambient aerosol particles and those generated by in situ bubbling experiments confines the microgel source to the open leads. The demonstrated occurrence of polysaccharides in surface sea waters and in air, with surface-active and hygroscopic properties, has shown their potential to serve as cloud condensation nuclei and subsequently promote cloud-drop activation in the pristine high Arctic. Presumably this possibility may renew interest in the complex but fascinating interactions between marine biology, aerosol, clouds and climate. / At the time of doctoral defence, the following paper was unpublished and had a status as follows: Paper 4: Manuscript

Um die beiden Hypothesen, dass (1) die Anzahl der Doppelbindungen der veresterten Fettsäuren einen Einfluss auf die Mutagenität der DME hat, und (2) dass die Oxidation (künstliche Alterung) verschiedener FAME und Blends höhere Mutagenität der DME bewirkt, zu untersuchen, wurden Abgasproben der folgenden Kraftstoffe verwendet: DK, PME, RME, LME, B20, B20alt, B20E2, B20altE2, RMEalt. Die Abgasproben wurden über Testläufe mit einem Mercedes-Benz OM 906 Euro-IIIMotor, der im ESC Testzyklus betrieben wurde, gewonnen. Die Mutagenität der Abgasproben wurde mittels des Ames-Tests untersucht. Sowohl die Positiv- als auch die Negativkontrollen bestätigten, dass die Reagenzien und Teststämme für die Versuche geeignet waren. Die Ergebnisse zeigten, dass sich die unter Punkt 1.5.1 (S. 17) beschriebene Hypothese, dass die Anzahl der Doppelbindungen der veresterten Fettsäuren einen Einfluss auf die Mutagenität der DME hat, bestätigte. Sowohl bei den Kondensaten, als auch den Partikulaten konnte gezeigt werden, dass die DME der FAME mit der geringeren Anzahl an mehrfach ungesättigten Fettsäuren signifikant geringer mutagen waren, als die DME der FAME mit der höheren Anzahl an mehrfach ungesättigten Fettsäuren. So ergab sich eine Reihenfolge der FAME mit aufsteigender Mutagenität ihrer DME: PME < RME < LME. Dieses Ergebnis war vor allem bei den Kondensaten in beiden Teststämmen (TA98, TA100) mit als auch ohne metabolische Aktivierung und bei den Partikulaten im Stamm TA98 ohne metabolische Aktivierung zu sehen. Die zweite Hypothese, dass die Oxidation (künstliche Alterung) verschiedener FAME und Blends höhere Mutagenität der DME bewirkt, wurde widerlegt. Zur Untersuchung dieser Hypothese wurden neben FAME (RME, RMEalt) folgende Blends verwendet: B20, B20alt, B20E2, B20altE2. Es konnten zwei signifikante Unterschiede erzielt werden, die jedoch für einen Beweis nicht ausreichten. Zusätzlich traten die signifikanten Unterschiede nicht im selben Teststamm auf und die Abgase der gealterten Form waren nicht durchgängig mutagener als die Abgase der nicht gealterten Form. Der Beweis eines signifikanten Unterschiedes, dass die Oxidation von FAME höhere Mutagenität der DME der dadurch gealterten FAME hervorruft, war daher nicht möglich. Weiterhin wurde ein Blend mit 2% Ethanol und 2% Butanol verschnitten. Der erhoffte Effekt der Alkoholadditivierung, eine Homogenisierung des FAME-Anteils durch Sedimentauflösung von oxidativen Abbauprodukten von FAME-Blends zu bewirken, blieb ebenso aus. Bei der Betrachtung der GPM zeigte sich, dass die FAME nicht die höchste GPM, aber die größte LOF besitzen. Dies spiegelte sich in der Mutagenität der DME der FAME verglichen mit denen des DK wieder. DK hatte zwar einen höheren Wert der GPM, aber einen kleineren Anteil der LOF. Die Abgase der FAME zeigten sich tendenziell mutagener als die des DK, jedoch ohne signifikante Ergebnisse. Dieser Effekt war v.a. bei den Kondensaten zu sehen. Die erhöhte Mutagenität der FAME-Abgase gegenüber den DK-Abgasen lässt sich anhand verschiedener Hypothesen erklären, die aber noch nicht ausreichend untersucht oder bewiesen sind.

Per pastaruosius tris dešimtmečius įvyko daug socialinių, ekonominių pokyčių, padidėjęs visuomenės sąmoningumas keičia gyvenimo būdą ir poreikį aukštesniems gyvenimo standartams. kurie savo ruožtu iškėlė labiau integruoto maisto saugos požiūrio reikalingumą. Pasikeitė žemės ūkio produktų gamybos, perdirbimo, pardavimo ir vartojimo struktūra. Padidėję gyvulinių produktų mainai sudarė sąlygas vartotojams gauti pigesnį ir įvairesnį maistą, bet tapo sunkiau atsekti produktų kelią nuo gamintojo iki galutinio vartotojo. Šiandieninė situacija skirtinguose Lietuvos žemės ūkio sektoriuose keičiasi. Mažėjant ūkių, mažėja, kai kurių auginamų gyvulių skaičius. Statistikos departamento duomenimis nurodoma, kad šiuo metu Lietuvoje yra 105 tūkst. ūkių, kuriuose auginami galvijai. 2012 m. pradžiai mūsų šalyje buvo priskaičiuota 748 tūkst. galvijų, 9264 tūkst. kiaulių, 9466,3 tūkst. paukščių, 79 tūkst. avių. Sparčiausiai auga paukštienos, ypač kalakutienos paklausa, palaipsniui didėja avienos, ožkienos, triušienos, žvėrienos poreikis. Tai siejama su vartotojų požiūrio į sveikesnį maistą kitimu. Atsakomybė už galutinį produktą, kuris patenka ant vartotojo stalo prasideda nuo pašaro gamintojo ir apima tiekėjus, gamybos įmones, augintojus, aptarnaujantį veterinarijos gydytoją, galimus prekybos tarpininkus, skerdyklas ir produkcijos perdirbimo įmones iki mažmeninės prekybos. Pirmoje vietoje turi būti saugumas, stabilumas ir skaidrumas visuose gamybos lygmenyse, taip pat duomenų perdavimo... [toliau žr. visą tekstą] / This final study is written in the Lithuanian language, containing 59 pages and includes: an introduction, literature review, materials and methods, results, conclusions, a list of used literature including references 140, tables 12 and pictures 4. Many social and economical changes have occurred within the three recent decades, increased consciousness of the society changes the life style and the need for higher standards of life, they subsequently revealed the necessity of more integrated attitude towards food safety. The structure of production, processing, sales and consumption of agricultural products has changed. Increased exchange of animal products allowed users to get cheaper food and bigger variety thereof, but tracing the path of products from the manufacturer to the end user became more difficult. Today the situation in different sectors of Lithuanian agriculture is changing. As the amount of farms is decreasing, the amount of some of the bred animals is decreasing as well. According to the data from the Department of Statistics, there currently are 105000 farms breeding cattle in Lithuania. In the beginning of 2012, there were 748000 cattle, 9264000 pigs, 9466300 birds, 79000 sheep in our country. The demand for poultry, especially turkey, is increasing the most, the need for sheep meat, goat meat, rabbit meat, game meat is gradually increasing. It is associated with the change of attitude of users towards healthier food. Responsibility for the final product... [to full text]

[Truncated abstract] Clinical magnetic resonance imaging (MRI) scanners were used to investigate the measurement and imaging of ferrimagnetic particle concentrations in biological tissues in vivo. The presence of ferrimagnetic particles tends to increase the proton transverse relaxation rate (R2) of water protons in tissue. A quantitative image of R2 can be generated using a series of single spin echo magnetic resonance images acquired using clinical MRI scanners and analysing the images using techniques based on that reported by Clark and St. Pierre (2000). If ferrimagnetic particles have a high enough concentration, there is a monotonic relationship between particle concentration and R2; therefore an image of R2 gives a map of the ferrimagnetic particle concentration in the tissue. These techniques were used to investigate the feasibility of in vivo measurement of the concentration and distribution of both synthetic and biogenic ferrimagnetic particles in tissue. Rabbit liver was loaded with ferrimagnetic particles of ?-Fe2O3 (designed for magnetic hyperthermia treatment of liver tumours) by injecting various doses of a suspension of the particles into the hepatic artery in vivo. R2 images of the livers in vivo, excised, and dissected were generated from a series of single spin-echo images. Mean R2 values for samples of ferrimagnetic-particle-loaded liver dissected into approximate 1 cm cubes were found to linearly correlate with tissue iron concentration over the range from approximately 0.1 to at least 2.7 mg Fe/g dry tissue when measured at room temperature. Changing the temperature of ferrimagnetic-particle-loaded samples of liver from 1?C to 37?C had no observable effect on tissue R2 values. However, a small but significant decrease in R2 was found for control samples containing no ferrimagnetic material on raising the temperature from 1?C to 37?C. Both chemically measured iron ii concentrations and mean R2 values for rabbit livers with implanted tumours tended to be higher than those measured for tumour-free liver. This study indicates that tissue R2 measurement and imaging by nuclear magnetic resonance may have a useful role in magnetic hyperthermia therapy protocols for the treatment of liver cancer. In order to investigate the use of clinical MRI scanners to measure biogenic ferrimagnetic particle concentrations in human brain tissue, agar gel based phantoms containing ferrimagnetic particles were made in order to determine the lower concentration detection limit for such particles in a homogenous medium. Magnetite/maghemite nanoparticles were synthesized in the presence of either dextran or polyvinyl alcohol, yielding cluster- and necklace-like aggregates, respectively. Magnetization, Mossbauer spectroscopy, and microscopy measurements indicated that the arrangement of the particles within the aggregates affects the magnetic properties of the particles resulting in smaller particles in the clusters having higher superparamagnetic blocking temperatures than larger particles in the necklaces.