459 resultados para STRESSOR CONTROLLABILITY
Resumo:
Den här undersökningen syftar till att svara på huruvida arbetsförmedlare anser arbetsförmedlingen som officiell institution behövs. Vidare undersöks arbetsmiljö, stress, stressorer och arbetsförmedlares bedömning av sin egen arbetsinsats. Undersökningen är kvantitativ och i form av enkät. Studien är begränsad till Gävleborgs län. Undersökningen bygger på 3 enkäter Arbetsförmedlares syn på sin arbetsinsats (ASSA) samt Percieved Stress Scale (PSS) och Hospital Anxiety and Depression Scale (HAD). Samtliga på vald arbetsplats med yrkestiteln arbetsförmedlare erbjöds att delta i undersökningen, totalt var det 31 personer som deltog. Undersökningen visar att tidspress är en stor stressor för arbetsförmedlare men vissa buffrar finns, så som socialt stöd och utbildning. PSS-resultat har jämförts individuellt mot HAD-resultaten och ett bekymmersamt resultat framkom, samtliga deltagare (10 %) som påvisar nedstämdhet har även mild till måttlig ångest och är stressade. Majoriteten av arbetsförmedlarna anser att arbetsförmedlingen behövs och är viktig för det svenska folket men endast hälften värderar sitt arbete som viktigare än det arbete rekryterings- och bemanningsföretag utför. Den ekonomiska kontrollen arbetsförmedlingen utövar ses inte som positiv och de arbetsmarknadspolitiska åtgärderna anses förslappa de arbetssökande. Slutledningen blir att arbetsförmedlingens roll i dagens samhälle är något utspelad.
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La definizione di “benessere animale” e le modalità di determinazione di tale parametro sono ancora ampiamente dibattute. C’è, però, una generale concordanza sul fatto che una condizione di malessere dia origine a variazioni fisiologiche e comportamentali che possono essere rilevate e misurate. Tra i parametri endocrini, il più studiato è, senza dubbio, il cortisolo, in quanto connesso con l’attivazione dell’asse ipotalamico-pituitario-surrenale in condizioni di stress e quindi ritenuto indicatore ideale di benessere, benché debba essere utilizzato con cautela in quanto un aumento dei livelli di questo ormone non si verifica con ogni tipo di stressor. Inoltre, si deve considerare che la raccolta del campione per effettuare le analisi, spesso implica il confinamento ed il contenimento degli animali e può essere, quindi, essa stessa un fattore stressante andando ad alterare i risultati. Alla luce delle suddette conoscenze gli obiettivi scientifici di questa ricerca, condotta sul gatto e sul cane, sono stati innanzitutto validare il metodo di dosaggio di cortisolo dal pelo e stabilire se tale dosaggio può rappresentare un indicatore, non invasivo, di benessere dell’animale (indice di “stress cronico”). In seguito, abbiamo voluto individuare i fattori di stress psico-sociale in gatti che vivono in gattile, in condizioni di alta densità, analizzando i correlati comportamentali ed ormonali dello stress e del benessere in questa condizione socio-ecologica, ricercando, in particolare, l’evidenza ormonale di uno stato di stress prolungato e la messa in atto di strategie comportamentali di contenimento dello stesso e il ruolo della marcatura visivo-feromonale, inoltre abbiamo effettuato un confronto tra oasi feline di diversa estensione spaziale per valutare come varia lo stress in rapporto allo spazio disponibile. Invece, nel cane abbiamo voluto evidenziare eventuali differenze dei livelli ormonali tra cani di proprietà e cani di canili, tra cani ospitati in diversi canili e tra cani che vivono in diverse realtà familiari; abbiamo voluto valutare gli effetti di alcuni arricchimenti sui cani di canile ed, infine, abbiamo analizzato cani sottoposti a specifici programmi si addestramento. Il primo importante ed originale risultato raggiunto, che risponde al primo obiettivo della ricerca, è stato la validazione del dosaggio radioimmunologico di cortisolo in campioni di pelo. Questo risultato, a nostro avviso, apre una nuova finestra sul campo della diagnostica endocrinologica metabolica. Attualmente, infatti, il monitoraggio ormonale viene effettuato su campioni ematici la cui raccolta prevede un elevato stress (stress da prelievo) per l’animale data l'invasività dell'operazione che modifica l’attività di ipotalamo-ipofisi-surrene e, dunque, provoca repentine alterazioni delle concentrazioni ormonali. Questa metodica offre, quindi, il vantaggio dell’estrema semplicità di raccolta del campione e, in più, il bassissimo costo del materiale utilizzato. Dalle ricerche condotte sui gatti di gattile sono scaturite preziose indicazioni per future indagini sullo stress e sul comportamento sociale felino. I risultati dell’analisi congiunta del comportamento e delle concentrazioni ormonali hanno evidenziato che la disponibilità di postazioni di marcatura visivo-feromonale ha un effetto positivo sia sugli indicatori comportamentali, sia su quelli ormonali di stress. I risultati dell’analisi delle concentrazioni di cortisolo, derivanti dal confronto tra sette oasi feline di diversa estensione spaziale hanno permesso di evidenziare un aumento dei livelli dell’ormone inversamente proporzionale allo spazio disponibile. Lo spazio disponibile, però, non è l’unico fattore da prendere in considerazione al fine di assicurare il benessere dell’animale infatti, nelle colonie che presentavano instabilità sociale e variabilità territoriale il cortisolo aveva valori elevati nonostante le notevoli disponibilità di spazio. Infine, si è potuto costatare come anche lo stare appartati, aumenti proporzionalmente con l’aumentare dello spazio. Questo comportamento risulta essere molto importante in quanto mitiga lo stress ed è da prendere in considerazione nell’allestimento di colonie feline. Infatti, nelle colonie di dimensioni ridotte dove lo stress è già alto, l’impossibilità dei soggetti di appartarsi può contribuire a peggiorare la situazione; ecco perché si dovrebbero creare luoghi artificiali per fornire ai gatti la possibilità di appartarsi, magari sfruttando gli spazi sopraelevati (tetti, alberi, ecc.). Per quanto riguarda il confronto tra cani di proprietà e cani di canile non sono state evidenziate differenze significative nei livelli di cortisolo nel pelo mentre abbiamo rilevato che quest’ultimi sono influenzati dalla disponibilità di spazio: infatti sia i cani di proprietà che vivevano in giardino, sia i cani dei canili che praticavano lo sgambamento presentavano livelli di cortisolo nel pelo più bassi rispetto, rispettivamente, ai cani di proprietà che vivevano in appartamento o appartamento/giardino e a quelli di canile che non praticavano lo sgambamento. L’arricchimento ambientale fornito ai cani di canile ha esercitato un’influenza positiva riducendo i livelli di cortisolo e migliorando la docilità dei soggetti, favorendone un’eventuale adozione. Si è inoltre messo in luce che i programmi di addestramento, eseguiti con tecniche “gentili”, non comportano situazioni stressanti per l’animale e aiutano i cani ad esprimere doti di equilibrio che rimarrebbero altrimenti celate dagli aspetti più istintivi del carattere. D’altra parte, l’impegno agonistico prima di una competizione e il livello di addestramento raggiunto dai cani, influenzano le concentrazioni di cortisolo a riposo e durante l’esercizio fisico. Questi risultati possono sicuramente dare utili suggerimenti per la gestione e la cura di gatti e cani al fine di migliorarne le condizioni di benessere.
Resumo:
The first part of my work consisted in samplings conduced in nine different localities of the salento peninsula and Apulia (Italy): Costa Merlata (BR), Punta Penne (BR), Santa Cesarea terme (LE), Santa Caterina (LE), Torre Inserraglio (LE), Torre Guaceto (BR), Porto Cesareo (LE), Otranto (LE), Isole Tremiti (FG). I collected data of species percentage covering from the infralittoral rocky zone, using squares of 50x50 cm. We considered 3 sites for location and 10 replicates for each site, which has been taken randomly. Then I took other data about the same places, collected in some years, and I combined them together, to do a spatial analysis. So I started from a data set of 1896 samples but I decided not to consider time as a factor because I have reason to think that in this period of time anthropogenic stressors and their effects (if present), didn’t change considerably. The response variable I’ve analysed is the covering percentage of an amount of 243 species (subsequently merged into 32 functional groups), including seaweeds, invertebrates, sediment and rock. 2 After the sampling, I have been spent a period of two months at the Hopkins Marine Station of Stanford University, in Monterey (California,USA), at Fiorenza Micheli's laboratory. I've been carried out statistical analysis on my data set, using the software PRIMER 6. My explorative analysis starts with a nMDS in PRIMER 6, considering the original data matrix without, for the moment, the effect of stressors. What comes out is a good separation between localities and it confirms the result of ANOSIM analysis conduced on the original data matrix. What is possible to ensure is that there is not a separation led by a geographic pattern, but there should be something else that leads the differences. Is clear the presence of at least three groups: one composed by Porto cesareo, Torre Guaceto and Isole tremiti (the only marine protected areas considered in this work); another one by Otranto, and the last one by the rest of little, impacted localities. Inside the localities that include MPA(Marine Protected Areas), is also possible to observe a sort of grouping between protected and controlled areas. What comes out from SIMPER analysis is that the most of the species involved in leading differences between populations are not rare species, like: Cystoseira spp., Mytilus sp. and ECR. Moreover I assigned discrete values (0,1,2) of each stressor to all the sites I considered, in relation to the intensity with which the anthropogenic factor affect the localities. 3 Then I tried to estabilish if there were some significant interactions between stressors: by using Spearman rank correlation and Spearman tables of significance, and taking into account 17 grades of freedom, the outcome shows some significant stressors interactions. Then I built a nMDS considering the stressors as response variable. The result was positive: localities are well separeted by stressors. Consequently I related the matrix with 'localities and species' with the 'localities and stressors' one. Stressors combination explains with a good significance level the variability inside my populations. I tried with all the possible data transformations (none, square root, fourth root, log (X+1), P/A), but the fourth root seemed to be the best one, with the highest level of significativity, meaning that also rare species can influence the result. The challenge will be to characterize better which kind of stressors (including also natural ones), act on the ecosystem; and give them a quantitative and more accurate values, trying to understand how they interact (in an additive or non-additive way).
Resumo:
Allergies are a complex of symptoms derived from altered IgE-mediated reactions of the immune system towards substances known as allergens. Allergic sensibilization can be of food or respiratory origin and, in particular, apple and hazelnut allergens have been identified in pollens or fruits. Allergic cross-reactivity can occur in a patient reacting to similar allergens from different origins, justifying the research in both systems as in Europe a greater number of people suffers from apple fruit allergy, but little evidence exists about pollen. Apple fruit allergies are due to four different classes of allergens (Mal d 1, 2, 3, 4), whose allergenicity is related both to genotype and tissue specificity; therefore I have investigated their presence also in pollen at different time of germination to clarify the apple pollen allergenic potential. I have observed that the same four classes of allergens found in fruit are expressed at different levels also in pollen, and their presence might support that the apple pollen can be considered allergenic as the fruit, deducing that apple allergy could also be indirectly caused by sensitization to pollen. Climate changes resulting from increases in temperature and air pollution influence pollen allergenicity, responsible for the dramatic raise in respiratory allergies (hay fever, bronchial asthma, conjunctivitis). Although the link between climate change and pollen allergenicity is proven, the underlying mechanism is little understood. Transglutaminases (TGases), a class of enzymes able to post-translationally modify proteins, are activated under stress and involved in some inflammatory responses, enhancing the activity of pro-inflammatory phospholipase A2, suggesting a role in allergies. Recently, a calcium-dependent TGase activity has been identified in the pollen cell wall, raising the possibility that pollen TGase may have a role in the modification of pollen allergens reported above, thus stabilizing them against proteases. This enzyme can be involved also in the transamidation of proteins present in the human mucosa interacting with surface pollen or, finally, the enzyme itself can represent an allergen, as suggested by studies on celiac desease. I have hypothesized that this pollen enzyme can be affected by climate changes and be involved in exhacerbating allergy response. The data presented in this thesis represent a scientific basis for future development of studies devoted to verify the hypothesis set out here. First, I have demonstrated the presence of an extracellular TGase on the surface of the grain observed either at the apical or the proximal parts of the pollen-tube by laser confocal microscopy (Iorio et al., 2008), that plays an essential role in apple pollen-tube growth, as suggested by the arrest of tube elongation by TGase inhibitors, such as EGTA or R281. Its involvement in pollen tube growth is mainly confirmed by the data of activity and gene expression, because TGase showed a peak between 15 min and 30 min of germination, when this process is well established, and an optimal pH around 6.5, which is close to that recorded for the germination medium. Moreover, data show that pollen TGase can be a glycoprotein as the glycosylation profile is linked both with the activation of the enzyme and with its localization at the pollen cell wall during germination, because from the data presented seems that the active form of TGase involved in pollen tube growth and pollen-stylar interaction is more exposed and more weakly bound to the cell wall. Interestingly, TGase interacts with fibronectin (FN), a putative SAMs or psECM component, inducing possibly intracellular signal transduction during the interaction between pollen-stylar occuring in the germination process, since a protein immunorecognised by anti-FN antibody is also present in pollen, in particular at the level of pollen grain cell wall in a punctuate pattern, but also along the shank of the pollen tube wall, in a similar pattern that recalls the signal obtained with the antibody anti TGase. FN represents a good substrate for the enzyme activity, better than DMC usually used as standard substrate for animal TGase. Thus, this pollen enzyme, necessary for its germination, is exposed on the pollen surface and consequently can easily interact with mucosal proteins, as it has been found germinated pollen in studies conducted on human mucus (Forlani, personal communication). I have obtained data that TGase activity increases in a very remarkable way when pollen is exposed to stressful conditions, such as climate changes and environmental pollution. I have used two different species of pollen, an aero allergenic (hazelnut, Corylus avellana) pollen, whose allergenicity is well documented, and an enthomophylus (apple, Malus domestica) pollen, which is not yet well characterized, to compare data on their mechanism of action in response to stressors. The two pollens have been exposed to climate changes (different temperatures, relative humidity (rH), acid rain at pH 5.6 and copper pollution (3.10 µg/l)) and showed an increase in pollen surface TGase activity that is not accompanied to an induced expression of TGase immunoreactive protein with AtPNG1p. Probably, climate change induce an alteration or damage to pollen cell wall that carries the pollen grains to release their content in the medium including TGase enzyme, that can be free to carry out its function as confirmed by the immunolocalisation and by the in situ TGase activity assay data; morphological examination indicated pollen damage, viability significantly reduced and in acid rain conditions an early germination of apple pollen, thus possibly enhancing the TGase exposure on pollen surface. Several pollen proteins were post-translationally modified, as well as mammalian sPLA2 especially with Corylus pollen, which results in its activation, potentially altering pollen allergenicity and inflammation. Pollen TGase activity mimicked the behaviour of gpl TGase and AtPNG1p in the stimulation of sPLA2, even if the regulatory mechanism seems different to gpl TGase, because pollen TGase favours an intermolecular cross-linking between various molecules of sPLA2, giving rise to high-molecular protein networks normally more stable. In general, pollens exhibited a significant endogenous phospholipase activity and it has been observed differences according to the allergenic (Corylus) or not-well characterized allergenic (Malus) attitude of the pollen. However, even if with a different intensity level in activation, pollen enzyme share the ability to activate the sPLA2, thus suggesting an important regulatory role for the activation of a key enzyme of the inflammatory response, among which my interest was addressed to pollen allergy. In conclusion, from all the data presented, mainly presence of allergens, presence of an extracellular TGase, increasing in its activity following exposure to environmental pollution and PLA2 activation, I can conclude that also Malus pollen can behave as potentially allergenic. The mechanisms described here that could affect the allergenicity of pollen, maybe could be the same occurring in fruit, paving the way for future studies in the identification of hyper- and hypo- allergenic cultivars, in preventing environmental stressor effects and, possibly, in the production of transgenic plants.
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Die Literatur zu Arbeitszufriedenheit zeigt, dass die Bedeutung verschiedener Komponenten der Arbeitszufriedenheit zwischen einzelnen Kulturkreisen schwankt. Um diese unterschiedlichen Befunde zu erklären, bietet die "Affective Events Theory" einen Erklärungsrahmen an, der den Einfluss affektiver Erlebnisse auf verschiedene Einstellungskomponenten abbildet. Diese Studie hatte zum Ziel, bei Beschäftigten mit unterschiedlichen kulturellen Hintergründen, den Einfluss von "daily hassles" auf Empfindungen und verschiedene Komponenten der Arbeitszufriedenheit zu untersuchen. Da sich bei Mitgliedern independenter und interdependenter Kulturen verschiedene Interpretationen der gleichen Situationen finden, die anschließend zu unterschiedlichen affektiven und kognitive Reaktionen führen, wurden insgesamt 244 Beschäftigte aus Deutschland (independent) und Japan (interdependent) befragt. Sie erinnerten selbst erlebte, berufliche "daily hassles" hinsichtlich der kognitiven Dimensionen "Verursacher" und "Kontrollierbarkeit" und gaben ihre Reaktionen auf Fragebögen an. Allgemeine Arbeitszufriedenheit wurde als Konstrukt konzipiert, das aus einer affektiven und einer kognitiven Komponente besteht. Es wurde vermutet, dass die Befragten abhängig vom kulturellen Hintergrund und der kognitiven Struktur der "daily hassles" unterschiedliche Empfindungen zeigen, die die affektiven und kognitiven Komponenten der Arbeitszufriedenheit unterschiedlich beeinflussen. Zudem wurde angenommen, dass allgemeine Arbeitszufriedenheit im jeweiligen Kulturkreis durch diese beiden Komponenten unterschiedlich stark beeinflusst wird. Die Ergebnisse der Regressionsanalysen eines grafischen Kettenmodells konnten diese Annahmen zum großen Teil bestätigen: in independenten Kulturkreisen erweist sich allgemeine Arbeitszufriedenheit als ein aus zwei Komponenten bestehendes Konstrukt mit einer kognitiven und einer affektiven Komponente; in interdependenten Kulturen hingegen entspricht allgemeine Arbeitszufriedenheit vornehmlich einer affektiven Komponente. Es zeigte sich, dass die affektive Komponente in beiden Kulturkreisen durch unterschiedliche Empfindungen beeinflusst wird. Auf den ersten Blick gleiche, berufliche Ereignisse werden abhängig vom kulturellen Hintergrund unterschiedlich interpretiert und lösen differierende Empfindungen aus. Diese beeinflussen ihrerseits verschiedene Komponenten der Arbeitszufriedenheit unterschiedlich. Entgegen dem aktuellen Stand der Literatur spiegeln Angaben zu allgemeiner Arbeitszufriedenheit somit nicht ein universell einheitliches (kognitives) Phänomen wider sondern sind abhängig vom kulturellen Hintergrund unterschiedlich stark affektiv besetzt.
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Nella prima parte viene ricostruito il concetto di vincolo espropriativo alla luce dell’elaborazione della giurisprudenza della Corte costituzionale e della Corte EDU, giungendo alla conclusione che rientrano in tale concetto le limitazioni al diritto di proprietà che: - derivano da scelte discrezionali dell’Amministrazione non correlate alle caratteristiche oggettive del bene; - superano la normale tollerabilità nel senso che impediscono al proprietario la prosecuzione dell’uso in essere o incidono sul valore di mercato del bene in modo sproporzionato rispetto alle oggettive caratteristiche del bene e all’interesse pubblico perseguito. Ragione di fondo della teoria dei vincoli è censurare l’eccessiva discrezionalità del potere urbanistico, imponendo una maggiore obiettività e controllabilità delle scelte urbanistiche. Dalla teoria dei vincoli consegue altresì che nell’esercizio del potere urbanistico l’Amministrazione, pur potendo differenziare il territorio, deve perseguire l’obiettivo del riequilibrio economico degli interessi incisi dalle sue determinazioni. L’obbligo della corresponsione dell’indennizzo costituisce la prima forma di perequazione urbanistica. Nel terzo e nel quarto capitolo viene analizzata la giurisprudenza civile e amministrativa in tema di vincoli urbanistici, rilevandone la non corrispondenza rispetto all’elaborazione della Corte costituzionale e l’incongruità dei risultati applicativi. Si evidenzia in particolare la necessità del superamento del criterio basato sulla distinzione zonizzazioni-localizzazioni e di considerare conformative unicamente quelle destinazioni realizzabili ad iniziativa privata che in concreto consentano al proprietario di conseguire un’utilità economica proporzionata al valore di mercato del bene. Nel quinto capitolo viene analizzato il rapporto tra teoria dei vincoli e perequazione urbanistica, individuandosi il discrimine tra i due diversi istituti non solo nel consenso, ma anche nella proporzionalità delle reciproche prestazioni negoziali. Attraverso la perequazione non può essere attribuito al proprietario un’utilità inferiore a quella che gli deriverebbe dall’indennità di esproprio.
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This work is about the role that environment plays in the production of evolutionary significant variations. It starts with an historical introduction about the concept of variation and the role of environment in its production. Then, I show how a lack of attention to these topics may lead to serious mistakes in data interpretation. A statistical re-analysis of published data on the effects of malnutrition on dental eruption, shows that what has been interpreted as an increase in the mean value, is actually linked to increase of variability. In Chapter 3 I present the topic of development as a link between variability and environmental influence, giving a review of the possible mechanisms by which development influences evolutionary dynamics. Chapter 4 is the core chapter of the thesis; I investigated the role of environment in the development of dental morphology. I used dental hypoplasia as a marker of stress, characterizing two groups. Comparing the morphology of upper molars in the two groups, three major results came out: (i) there is a significant effect of environmental stressors on the overall morphology of upper molars; (ii) the developmental response increases morphological variability of the stressed population; (iii) increase of variability is directional: stressed individuals have increased cusps dimensions and number. I also hypothesized the molecular mechanisms that could be responsible of the observed effects. In Chapter 5, I present future perspectives for developing this research. The direction of dental development response is the same direction of the trend in mammalian dental evolution. Since malnutrition triggers the developmental response, and this particular kind of stressor must have been very common in our class evolutionary history, I propose the possibility that environmental stress actively influenced mammals evolution. Moreover, I discuss the possibility of reconsidering the role of natural selection in the evolution of dental morphology.
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This thesis provides a thoroughly theoretical background in network theory and shows novel applications to real problems and data. In the first chapter a general introduction to network ensembles is given, and the relations with “standard” equilibrium statistical mechanics are described. Moreover, an entropy measure is considered to analyze statistical properties of the integrated PPI-signalling-mRNA expression networks in different cases. In the second chapter multilayer networks are introduced to evaluate and quantify the correlations between real interdependent networks. Multiplex networks describing citation-collaboration interactions and patterns in colorectal cancer are presented. The last chapter is completely dedicated to control theory and its relation with network theory. We characterise how the structural controllability of a network is affected by the fraction of low in-degree and low out-degree nodes. Finally, we present a novel approach to the controllability of multiplex networks
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This thesis deals with the analytic study of dynamics of Multi--Rotor Unmanned Aerial Vehicles. It is conceived to give a set of mathematical instruments apt to the theoretical study and design of these flying machines. The entire work is organized in analogy with classical academic texts about airplane flight dynamics. First, the non--linear equations of motion are defined and all the external actions are modeled, with particular attention to rotors aerodynamics. All the equations are provided in a form, and with personal expedients, to be directly exploitable in a simulation environment. This has requited an answer to questions like the trim of such mathematical systems. All the treatment is developed aiming at the description of different multi--rotor configurations. Then, the linearized equations of motion are derived. The computation of the stability and control derivatives of the linear model is carried out. The study of static and dynamic stability characteristics is, thus, addressed, showing the influence of the various geometric and aerodynamic parameters of the machine and in particular of the rotors. All the theoretic results are finally utilized in two interesting cases. One concerns the design of control systems for attitude stabilization. The linear model permits the tuning of linear controllers gains and the non--linear model allows the numerical testing. The other case is the study of the performances of an innovative configuration of quad--rotor aircraft. With the non--linear model the feasibility of maneuvers impossible for a traditional quad--rotor is assessed. The linear model is applied to the controllability analysis of such an aircraft in case of actuator block.
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Natural systems face pressures exerted by natural physical-chemical forcings and a myriad of co-occurring human stressors that may interact to cause larger than expected effects, thereby presenting a challenge to ecosystem management. This thesis aimed to develop new information that can contribute to reduce the existing knowledge gaps hampering the holistic management of multiple stressors. I undertook a review of the state-of-the-art methods to detect, quantify and predict stressor interactions, identifying techniques that could be applied in this thesis research. Then, I conducted a systematic review of saltmarsh multiple stressor studies in conjunction with a multiple stressor mapping exercise for the study system in order to infer potential important synergistic stressor interactions. This analysis identified key stressors that are affecting the study system, but also pointed to data gaps in terms of driver and pressure data and raised issues for potentially overlooked stressors. Using field mesocosms, I explored how a local stressor (nutrient availability) affects the responses of saltmarsh vegetation to a global stressor (increased inundation) in different soil types. Results indicate that saltmarsh vegetation would be more drastically affected by increased inundation in low than in medium organic matter soils, and especially in estuaries already under high nutrient availability. In another field experiment, I examined the challenges of managing co-occurring and potentially interacting local stressors on saltmarsh vegetation: recreational trampling and smothering by deposition of excess macroalgal wrack due to high nutrient loads. Trampling and wrack prevention had interacting effects, causing non-linear responses of the vegetation to simulated management of these stressors, such that vegetation recovered only in those treatments simulating the combined prevention of both stressors. During this research I detected, using molecular genetic methods, a widespread presence of S. anglica (and to a lesser extent S. townsendii), two previously unrecorded non-native Spartinas in the study areas.
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In der vorliegenden Arbeit wurde Neuroglobin (Ngb), ein evolutiv altes und in Metazoen konserviertes respiratorisches Protein, funktionell untersucht. Mittels des induzierbaren Tet on / Tet off Systems wurde Ngb ektopisch in der murinen Leber und im Gehirn überexprimiert. Die Transkriptome von Leber und Gehirnregionen Ngb-transgener Mäuse wurden mittels Microarrays und RNA-Seq im Vergleich zum Wildtyp analysiert, um Auswirkungen der Ngb-Überexpression zu ermitteln. Die Transkriptom-Analyse in Leber und Gehirn zeigte eine nur geringe Anzahl differenziell regulierter Gene und Stoffwechselwege nach Ngb-Überexpression. Ngb transgene Mäuse wurden CCl4-induziertem ROS-Stress ausgesetzt und die Leberfunktion untersucht. Zudem wurden primäre Hepatozyten-Kulturen etabliert und in diesen in vitro die extrinsische Apoptose induziert. Die Stressversuche zeigten: (i) Die Ngb-Überexpression hat keine protektive Wirkung in der Leber in vivo. (ii) In Leberzellen in vitro hingegen verminderte eine Ngb-Überexpression effizient die Aktivierung der apoptotischen Kaskade. Eine protektive Wirkung von Ngb ist vermutlich von betrachtetem Gewebe und dem verwendeten Stressor abhängig und keine generelle, selektierte Funktion des Proteins.rnWeiterhin wurde eine Ngb-KnockOut-Mauslinie mit einem LacZ-KnockIn-Genotyp etabliert. Hierbei zeigten die KO-Mäuse keinen offensichtlichen Phänotyp in ihrer Entwicklung, Fortpflanzung und Retina-Funktion. Unter Verwendung des LacZ-Knockin-Konstrukts konnten kontrovers diskutierte Ngb-Expressionsorte im adulten Mausgehirn (Hippocampus, Cortex und Cerebellum) sowie in Testes experimentell bestätigt werden. Parallel wurden öffentlich verfügbare RNA-Seq Datensätze ausgewertet, um die regionale Ngb-Expression systematisch ohne Antikörper-assoziierte Spezifitätsprobleme zu charakterisieren. Eine basale Ngb-Expression (RPKM: ~1-5) wurde im Hippocampus, Cortex und Cerebellum, sowie in Retina und Testes ermittelt. Eine 20-40fach höhere, starke Expression (RPKM: ~160) wurde im Hypothalamus bzw. im Hirnstamm nachgewiesen. Die „digitale“ Expressionsuntersuchung wurde mittels qRT-PCR und Western Blot bestätigt. Dieses Expressionsprofil von Ngb in der Maus weist auf eine besondere funktionelle Bedeutung von Ngb im Hypothalamus hin. Eine Funktion von Ngb in der Sauerstoffversorgung der Retina und eine generelle Funktion von Ngb in der Protektion von Neuronen sind mit dem beobachteten Expressionsspektrum weniger gut vereinbar.
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Stress response can be considered a consequence of psychological or physiological threats to the human organism. Elevated cortisol secretion represents a biological indicator of subjective stress. The extent of subjectively experienced stress depends on individual coping strategies or self-regulation skills. Because of their experience with competitive pressure, athletes might show less pronounced biological stress responses during stressful events compared to non-athletes. In the present study, the short version of the Berlin Intelligence Structure Test, a paper-pencil intelligence test, was used as an experimental stressor. Cortisol responses of 26 female Swiss elite athletes and 26 female non-athlete controls were compared. Salivary free cortisol responses were measured 15 minutes prior to, as well as immediately before and after psychometric testing. In both groups, a significant effect of time was found: High cortisol levels prior to testing decreased significantly during the testing session. Furthermore, athletes exhibited reliably lower cortisol levels than non-athlete controls. No significant interaction effects could be observed. The overall pattern of results supports the idea that elite athletes show a less pronounced cortisol-related stress response due to more efficient coping strategies.
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Elevated levels of maternal androgens in avian eggs affect numerous traits, including oxidative stress. However, current studies disagree as to whether prenatal androgen exposure enhances or ameliorates oxidative stress. Here, we tested how prenatal testosterone exposure affects oxidative stress in female domestic chickens (Gallus gallus) during the known oxidative challenge of an acute stressor. Prior to incubation, eggs were either injected with an oil vehicle or 5 ng testosterone. At either 17 or 18 days post-hatch, several oxidative stress markers were assessed from blood taken before and after a 20 min acute stressor, as well as following a 25 min recovery from the stressor. We found that, regardless of yolk treatment, during both stress and recovery all individuals were in a state of oxidative stress, with elevated levels of oxidative damage markers accompanied by a reduced total antioxidant capacity. In addition, testosterone-exposed individuals exhibited poorer DNA damage repair efficiencies in comparison with control individuals. Our work suggests that while yolk androgens do not alter oxidative stress directly, they may impair mechanisms of oxidative damage repair.
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Over the last two decades modern psychosomatic research has found multiple evidence for an impact of psychosocial factors on the control of arterial blood pressure as well as the development of arterial hypertension. This narrative review focuses first on the current stress concept and factors that influence the degree of blood pressure change following a psychosocial stressor. Second, relevant psychosocial factors associated with blood pressure are presented such as marital status, social support, socioeconomic status and work conditions. In addition, the influence of personality and cognition on blood pressure will be discussed. The second part focuses on the outcome of cognitive-behavioral therapies and relaxation techniques as a means to effectively control blood pressure. In conclusion, there is now good evidence showing that psychosocial factors and stressors may increase blood pressure. The working environment, the socioeconomic status as well as aspects of personality and cognitive factors like rumination may also impact blood pressure with to an extent that is clinically relevant. With respect to therapeutic options, cognitive-behavioral interventions, combined with relaxation techniques all fitting the needs of the individual patient best can offer a clinically meaningful contribution of an effective blood pressure control.
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In order to improve the ability to link chemical exposure to toxicological and ecological effects, aquatic toxicology will have to move from observing what chemical concentrations induce adverse effects to more explanatory approaches, that are concepts which build on knowledge of biological processes and pathways leading from exposure to adverse effects, as well as on knowledge on stressor vulnerability as given by the genetic, physiological and ecological (e.g., life history) traits of biota. Developing aquatic toxicology in this direction faces a number of challenges, including (i) taking into account species differences in toxicant responses on the basis of the evolutionarily developed diversity of phenotypic vulnerability to environmental stressors, (ii) utilizing diversified biological response profiles to serve as biological read across for prioritizing chemicals, categorizing them according to modes of action, and for guiding targeted toxicity evaluation; (iii) prediction of ecological consequences of toxic exposure from knowledge of how biological processes and phenotypic traits lead to effect propagation across the levels of biological hierarchy; and (iv) the search for concepts to assess the cumulative impact of multiple stressors. An underlying theme in these challenges is that, in addition to the question of what the chemical does to the biological receptor, we should give increasing emphasis to the question how the biological receptor handles the chemicals, i.e., through which pathways the initial chemical-biological interaction extends to the adverse effects, how this extension is modulated by adaptive or compensatory processes as well as by phenotypic traits of the biological receptor.