9,391 research outputs found

    Norsk rå kumelk, en kilde til zoonotiske patogener?

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    The worldwide emerging trend of eating “natural” foods, that has not been processed, also applies for beverages. According to Norwegian legislation, all milk must be pasteurized before commercial sale but drinking milk that has not been heat-treated, is gaining increasing popularity. Scientist are warning against this trend and highlights the risk of contracting disease from milkborne microorganisms. To examine potential risks associated with drinking unpasteurized milk in Norway, milk- and environmental samples were collected from dairy farms located in south-east of Norway. The samples were analyzed for the presence of specific zoonotic pathogens; Listeria monocytogenes, Campylobacter spp., and Shiga toxin-producing Escherichia coli (STEC). Cattle are known to be healthy carriers of these pathogens, and Campylobacter spp. and STEC have a low infectious dose, meaning that infection can be established by ingesting a low number of bacterial cells. L. monocytogenes causes one of the most severe foodborne zoonotic diseases, listeriosis, that has a high fatality rate. All three pathogens have caused milk borne disease outbreaks all over the world, also in Norway. During this work, we observed that the prevalence of the three examined bacteria were high in the environment at the examined farms. In addition, 7% of the milk filters were contaminated by STEC, 13% by L. monocytogenes and 4% by Campylobacter spp. Four of the STEC isolates detected were eaepositive, which is associated with the capability to cause severe human disease. One of the eae-positive STEC isolates were collected from a milk filter, which strongly indicate that Norwegian raw milk may contain potential pathogenic STEC. To further assess the possibilities of getting ill by STEC after consuming raw milk, we examined the growth of the four eae-positive STEC isolates in raw milk at different temperatures. All four isolates seemed to have ability to multiply in raw milk at 8°C, and one isolate had significant growth after 72 hours. Incubation at 6°C seemed to reduce the number of bacteria during the first 24 hours before cell death stopped. These findings highlight the importance of stable refrigerator temperatures, preferable < 4°C, for storage of raw milk. The L. monocytogenes isolates collected during this study show genetic similarities to isolates collected from urban and rural environmental locations, but different clones were predominant in agricultural environments compared to clinical and food environments. However, the results indicate that the same clone can persist in a farm over time, and that milk can be contaminated by L. monocytogenes clones present in farm environment. Despite testing small volumes (25 mL) of milk, we were able to isolate both STEC and Campylobacter spp. directly from raw milk. A proportion of 3% of the bulk tank milk and teat milk samples were contaminated by Campylobacter spp. and one STEC was isolated from bulk tank milk. L monocytogenes was not detected in bulk tank milk, nor in teat milk samples. The agricultural evolvement during the past decades have led to larger production units and new food safety challenges. Dairy cattle production in Norway is in a current transition from tie-stall housing with conventional pipeline milking systems, to modern loose housing systems with robotic milking. The occurrence of the three pathogens in this project were higher in samples collected from farms with loose housing compared to those with tiestall housing. Pasteurization of cow’s milk is a risk reducing procedure to protect consumers from microbial pathogens and in most EU countries, commercial distribution of unpasteurized milk is legally restricted. Together, the results presented in this thesis show that the animal housing may influence the level of pathogenic bacteria in the raw milk and that ingestion of Norwegian raw cow’s milk may expose consumers to pathogenic bacteria which can cause severe disease, especially in children, elderly and in persons with underlying diseases. The results also highlight the importance of storing raw milk at low temperatures between milking and consumption.Å spise mat som er mindre prosessert og mer «naturlig» er en pågående trend i Norge og i andre deler av verden. Interessen for å drikke melk som ikke er varmebehandlet, såkalt rå melk, er også økende. I Norge er det påbudt å pasteurisere melk før kommersielt salg for å beskytte forbrukeren mot sykdomsfremkallende mikroorganismer. Fagfolk advarer mot å drikke rå melk, og påpeker risikoen for å bli syk av patogene bakterier som kan finnes i melken. I denne avhandlingen undersøker vi den potensielle risikoen det medfører å drikke upasteurisert melk fra Norge. I tillegg til å samle inn tankmelk- og speneprøver fra melkegårder i sørøst Norge, samlet vi også miljøprøver fra de samme gårdene for å kartlegge forekomst og for å identifisere potensielle mattrygghetsrisikoer i melkeproduksjonen. Alle prøvene ble analysert for de zoonotiske sykdomsfremkallende bakteriene Listeria monocytogenes, Campylobacter spp., og Shiga toksin-produserende Escherichia coli (STEC). Kyr kan være friske smittebærere av disse bakteriene, som dermed kan etablere et reservoar på gårdene. Bakteriene kan overføres fra gårdsmiljøet til melkekjeden og dermed utfordre mattryggheten. Disse bakteriene har forårsaket melkebårne sykdomsutbrudd over hele verden, også i Norge. Campylobacter spp. og STEC har lav infeksiøs dose, som vil si at man kan bli syk selv om man bare inntar et lavt antall bakterieceller. L. monocytogenes kan gi sykdommen listeriose, en av de mest alvorlige matbårne zoonotiske sykdommene vi har i den vestlige verden. Resultater fra denne oppgaven viser en høy forekomst av de tre patogenene i gårdsmiljøet. I tillegg var 7% av melkefiltrene vi testet positive for STEC, 13% positive for L. monocytogenes og 4% positive for Campylobacter spp.. Fire av STEC isolatene bar genet for Intimin, eae, som er ansett som en viktig virulensfaktor som øker sjansen for alvorlig sykdom. Ett av de eae-positive isolatene ble funnet i et melkefilter, noe som indikerer at norsk rå melk kan inneholde patogene STEC. For å videre vurdere risikoen for å bli syk av STEC fra rå melk undersøkte vi hvordan de fire eae-positive isolatene vokste i rå melk lagret ved forskjellige temperaturer. For alle isolatene økte antall bakterier etter lagring ved 8°C, og for et isolat var veksten signifikant. Etter lagring ved 6°C ble antallet bakterier redusert de første 24 timene, deretter stoppet reduksjonen i antall bakterier. Disse resultatene viser hvor viktig det er å ha stabil lav lagringstemperatur for rå melk, helst < 4°C. L. monocytogenes isolatene som ble samlet inn fra melkegårdene viste genetiske likheter med isolater samlet inn fra urbane og rurale miljøer rundt omkring i Norge. Derimot var kloner som dominerte i landbruksmiljøet forskjellige fra kliniske isolater og isolater fra matproduksjonslokaler. Videre så man at en klone kan persistere på en gård over tid og at melk kan kontamineres av L. monocytogenes kloner som er til stede i gårdsmiljøet. Til tross for små testvolum av tankmelken (25 mL) fant vi både STEC og Campylobacter spp. i melkeprøvene. 3% av tankmelkprøvene og speneprøvene var positive for Campylobacter spp. og ett STEC isolat ble funnet i tankmelk. L. monocytogenes ble ikke funnet direkte i melkeprøvene. Landbruket i Norge er i stadig utvikling der besetningene blir større, men færre. Melkebesetningene er midt i en overgang der tradisjonell oppstalling med melking på bås byttes ut med løsdriftssystemer og melkeroboter. Forekomsten av de tre patogenene funnet i denne studien var høyere i besetningene med løsdrift sammenliknet med besetningene som hadde melkekyrne oppstallet på bås. Pasteurisering er et viktig forebyggende tiltak for å beskytte konsumenter fra mikrobielle patogener, og i de fleste EU-land er kommersielt salg av rå melk juridisk begrenset. Denne studien viser at oppstallingstype kan påvirke nivåene av patogene bakterier i gårdsmiljøet og i rå melk. Inntak av rå melk kan eksponere forbruker for patogene bakterier som kan gi alvorlig sykdom, spesielt hos barn, eldre og personer med underliggende sykdommer. Resultatene underbygger viktigheten av å pasteurisere melk for å sikre mattryggheten, og at det er avgjørende å lagre rå melk ved kontinuerlig lave temperaturer for å forebygge vekst av zoonotiske patogener

    Quantification of the Tumor immune Stroma (QTiS) and the metabolic checkpoint molecules in pancreatic cancer: comparison between primary and metastatic tumor

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    Pancreatic cancer (PC) remains one of the most lethal cancers in the world. Currently, surgical resection is still the most effective treatment for PC, yet it only works for a few early-stage patients. Although multiple efforts have been ongoing to treat metastatic pancreatic cancer, the outcome remains unsatisfactory. Previous studies have shown that immune imbalance within the tumor microenvironment (TME) promotes tumor progression. Furthermore, glucose metabolism is essential to providing energy for tumor growth, progression, and distant metastasis. There have been studies on tumor-infiltrating leukocytes (TILs) and energy metabolism in the TME of pancreatic cancer, while research on metastatic PC is unavailable because of the surgical treatment of metastatic pancreatic cancer. We were fortunate to have this opportunity to study 26 cases of metastatic PC in our institution. Quantification of the tumor immune stroma (QTiS) algorithm was used to quantify seven markers after immunohistochemical staining, including four markers of leukocytes (CD3+, CD8+, CD20+, and CD66b+) and three markers of metabolic checkpoint molecules (HIF-1α, GLUT1, PDHK1). Afterward, differences in tumor-infiltrating leukocytes (TILs) and metabolic checkpoint molecules (MCMs) between primary and metastatic lesions of metastatic pancreatic cancer were analyzed. Furthermore, the correlation between seven staining markers and clinical data, including overall survival (OS) and disease-free survival (DFS), was also analyzed. The results showed that the infiltration of CD3+, CD8+, and CD20+ in PC primary tumors was higher than that in metastatic tumors. High infiltration of CD20+ TILs (p=0.013) in primary tumors of PC correlates with improved overall survival, and high infiltration of CD8+ (p=0.023) in metastatic tumors of PC correlates with improved overall survival. Low level of platelets in blood circulation system associated with improved OS. The density of HIF-1α and PDHK1 in tumor cell area was higher than that in tumor stroma areas of primary and metastatic tumors. Low-density GLUT1 in tumor stroma areas of primary tumors (p=0.009) and metastatic tumors (p=0.01) of PC correlates with improved OS. Notably, in multivariate analysis, CD8+TILs (HR 0.196, 95% CI 0.044-0.872, p=0.032) in metastatic tumors of PC is an independent prognostic factor; and GLUT1 in tumor stromal areas of primary (HR 5.816, 95% CI 1.006-33.624, p=0.049) and metastatic (HR 5.056, 95% CI 1.258-20.324, p=0.022) tumors is independent prognostic factor to metastatic pancreatic cancer. Overall, the present study used the QTiS algorithm to quantify stroma tumor-infiltrating leukocytes in metastatic PC. We extended this method to quantify metabolic checkpoint molecules in tumor cell and stromal areas, efficiently analyzing IHC staining images. Furthermore, we depicted the characters and differences of TILs and MCMs between primary and metastatic lesions of metastatic PC and the correlation between TILs and MCMs with OS and DFS. Our work can contribute to a better understanding of the immune subtypes and energy metabolism in metastatic PC, which could be vital in improving the diagnosis, prognosis, and treatment of advanced PC

    Evaluation of radio-immunotherapy sequence on immunological responses and clinical outcomes in patients with melanoma brain metastases (ELEKTRA)

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    In patients with melanoma brain metastases (MBM), a combination of radiotherapy (RT) with immune checkpoint inhibitors (ICI) is routinely used. However, the best sequence of radio-immunotherapy (RIT) remains unclear. In an exploratory phase 2 trial, MBM patients received RT (stereotactic or whole-brain radiotherapy depending on the number of MBM) combined with ipilimumab (ipi) ± nivolumab (nivo) in different sequencing (Rad-ICI or ICI-Rad). Comparators arms included patients treated with ipi-free systemic treatment or without RT (in MBM-free patients). The primary endpoints were radiological and immunological responses in the peripheral blood. Secondary endpoints were progression-free survival (PFS) and overall survival (OS). Of 106 screened, 92 patients were included in the study. Multivariate analysis revealed an advantage for patients starting with RT (Rad-ICI) for overall response rate (RR: p = .007; HR: 7.88 (95%CI: 1.76-35.27)) and disease control rate (DCR: p = .036; HR: 6.26 (95%CI: 1.13-34.71)) with a trend for a better PFS (p = .162; HR: 1.64 (95%CI: 0.8-3.3)). After RT plus two cycles of ipi-based ICI in both RIT sequences, increased frequencies of activated CD4, CD8 T cells and an increase in melanoma-specific T cell responses were observed in the peripheral blood. Lasso regression analysis revealed a significant clinical benefit for patients treated with Rad-ICI sequence and immunological features, including high frequencies of memory T cells and activated CD8 T cells in the blood. This study supports increasing evidence that sequencing RT followed by ICI treatment may have better effects on the immunological responses and clinical outcomes in MBM patients

    Towards a sociology of conspiracy theories: An investigation into conspiratorial thinking on Dönmes

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    This thesis investigates the social and political significance of conspiracy theories, which has been an academically neglected topic despite its historical relevance. The academic literature focuses on the methodology, social significance and political impacts of these theories in a secluded manner and lacks empirical analyses. In response, this research provides a comprehensive theoretical framework for conspiracy theories by considering their methodology, political impacts and social significance in the light of empirical data. Theoretically, the thesis uses Adorno's semi-erudition theory along with Girardian approach. It proposes that conspiracy theories are methodologically semi-erudite narratives, i.e. they are biased in favour of a belief and use reason only to prove it. It suggests that conspiracy theories appear in times of power vacuum and provide semi-erudite cognitive maps that relieve alienation and ontological insecurities of people and groups. In so doing, they enforce social control over their audience due to their essentialist, closed-to-interpretation narratives. In order to verify the theory, the study analyses empirically the social and political significance of conspiracy theories about the Dönme community in Turkey. The analysis comprises interviews with conspiracy theorists, conspiracy theory readers and political parties, alongside a frame analysis of the popular conspiracy theory books on Dönmes. These confirm the theoretical framework by showing that the conspiracy theories are fed by the ontological insecurities of Turkish society. Hence, conspiracy theorists, most readers and some political parties respond to their own ontological insecurities and political frustrations through scapegoating Dönmes. Consequently, this work shows that conspiracy theories are important symptoms of society, which, while relieving ontological insecurities, do not provide politically prolific narratives

    A Molecular Approach to the Diagnosis, Assessment, Monitoring and Treatment of Pulmonary Non-Tuberculous Mycobacterial Disease

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    Introduction: Non-Tuberculous Mycobacteria (NTM) can cause disease of the lungs and sinuses, lymph nodes, joints and central nervous system as well as disseminated infections in immunocompromised individuals. Efforts to tackle infections in NTM are hampered by a lack of reliable biomarkers for diagnosis, assessment of disease activity, and prognostication. Aims: The broad aims of this thesis are: 1. to develop molecular assays capable of quantifying the 6 most common pathogenic mycobacteria (M. abscessus, M. avium, M. intracellulare, M. malmoense, M. kansasii, M. xenopi) and calculate comparative sensitivities and specificities for each assay. 2. to assess patients’ clinical course over 12 – 18 months by performing the developed molecular assays against DNA extracted from sputum from patients with NTM infection. 3. to assess dynamic bacterial changes of the lung microbiome in patients on treatment for NTM disease and those who are treatment na ve. Methods: DNA was extracted from a total of 410 sputum samples obtained from 38 patients who were either: • commencing treatment for either M. abscessus or Mycobacterium avium complex. • considered colonised with M. abscessus or Mycobacterium avium complex (i.e. cultured NTM but were not deemed to have infection as they did not meet ATS or BTS criteria for disease). • Diagnosed with cystic fibrosis (CF) or non-CF bronchiectasis but had never cultured NTM. For the development of quantitative molecular assays, NTM hsp65 gene sequences were aligned and interrogated for areas of variability. These variable regions enabled the creation of species specific probes. In vitro sensitivity and specificity for each probe was determined by testing each probe against a panel of plasmids containing hsp65 gene inserts from different NTM species. Quantification accuracy was determined by using each assay against a mock community containing serial dilutions of target DNA. Each sample was tested with the probes targeting: M. abscessus, M. avium and M. intracellulare producing a longitudinal assessment of NTM copy number during each patient’s clinical course. In addition, a total of 64 samples from 16 patients underwent 16S rRNA gene sequencing to characterise longitudinal changes in the microbiome of both NTM disease and controls. Results: In vitro sensitivity for the custom assays were 100% and specificity ranged from 91.6% to 100%. In terms of quantification accuracy, there was no significant difference between the measured results of each assay and the expected values when performed in singleplex. The assays were able to accurately determine NTM copy number to a theoretical limit of 10 copies/μl. When used against samples derived from human sputum and using culture results as a gold standard, the sensitivity of the assay for M. abscessus was found to be 0.87 and 0.86 for MAC. The specificity of the assay for M. abscessus was 0.95 and 0.62 for MAC. The negative predictive value of the assay for M. abscessus was 0.98 and 0.95 for MAC. This resulted in an AUC of 0.92 for M. abscessus and 0.74 for MAC. Longitudinal analysis of the lung microbiome using 16SrRNA gene sequencing showed that bacterial burden initially decreases after initiation of antibiotic therapy but begins to return to normal levels over several months of antibiotic therapy. This effect is mirrored by changes in alpha diversity. The decrease in bacterial burden and loss of alpha diversity was found to be secondary to significant changes in specific genera such as Veillonella and Streptococcus. The abundance of other Proteobacteria such as Pseudomonas remain relatively constant. Conclusion: The molecular assay has shown high in vitro sensitivity and specificity for the detection and accurate quantification of the 6 most commonly pathogenic NTM species. The assays successfully identified NTM DNA from human sputum samples. A notable association between NTM copy number and the cessation of one or more antibiotics existed (i.e. when one antibiotic was stopped because of patient intolerance, NTM copy number increased, often having been unrecordable prior to this). The qPCR assays developed in this thesis provide an affordable, real time and rapid measurement of NTM burden allowing clinicians to act on problematic results sooner than currently possible. There was no significant difference between the microbiome in bronchiectasis and cystic fibrosis nor was there a significant difference between the microbiome in patients requiring treatment for NTM and those who did not. Patients receiving treatment experienced an initial decrease in bacterial burden over the first weeks of treatment followed by a gradual increase towards baseline over the next weeks to months. This change was mirrored in measures of alpha diversity. Changes in abundance and diversity were accounted for by decreases in specific bacteria whilst the abundance of other bacteria increased, occupying the microbial niche created. These bacteria (for example Pseudomonas spp) are often associated with morbidity.Open Acces

    From wallet to mobile: exploring how mobile payments create customer value in the service experience

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    This study explores how mobile proximity payments (MPP) (e.g., Apple Pay) create customer value in the service experience compared to traditional payment methods (e.g. cash and card). The main objectives were firstly to understand how customer value manifests as an outcome in the MPP service experience, and secondly to understand how the customer activities in the process of using MPP create customer value. To achieve these objectives a conceptual framework is built upon the Grönroos-Voima Value Model (Grönroos and Voima, 2013), and uses the Theory of Consumption Value (Sheth et al., 1991) to determine the customer value constructs for MPP, which is complimented with Script theory (Abelson, 1981) to determine the value creating activities the consumer does in the process of paying with MPP. The study uses a sequential exploratory mixed methods design, wherein the first qualitative stage uses two methods, self-observations (n=200) and semi-structured interviews (n=18). The subsequent second quantitative stage uses an online survey (n=441) and Structural Equation Modelling analysis to further examine the relationships and effect between the value creating activities and customer value constructs identified in stage one. The academic contributions include the development of a model of mobile payment services value creation in the service experience, introducing the concept of in-use barriers which occur after adoption and constrains the consumers existing use of MPP, and revealing the importance of the mobile in-hand momentary condition as an antecedent state. Additionally, the customer value perspective of this thesis demonstrates an alternative to the dominant Information Technology approaches to researching mobile payments and broadens the view of technology from purely an object a user interacts with to an object that is immersed in consumers’ daily life

    Digital asset management via distributed ledgers

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    Distributed ledgers rose to prominence with the advent of Bitcoin, the first provably secure protocol to solve consensus in an open-participation setting. Following, active research and engineering efforts have proposed a multitude of applications and alternative designs, the most prominent being Proof-of-Stake (PoS). This thesis expands the scope of secure and efficient asset management over a distributed ledger around three axes: i) cryptography; ii) distributed systems; iii) game theory and economics. First, we analyze the security of various wallets. We start with a formal model of hardware wallets, followed by an analytical framework of PoS wallets, each outlining the unique properties of Proof-of-Work (PoW) and PoS respectively. The latter also provides a rigorous design to form collaborative participating entities, called stake pools. We then propose Conclave, a stake pool design which enables a group of parties to participate in a PoS system in a collaborative manner, without a central operator. Second, we focus on efficiency. Decentralized systems are aimed at thousands of users across the globe, so a rigorous design for minimizing memory and storage consumption is a prerequisite for scalability. To that end, we frame ledger maintenance as an optimization problem and design a multi-tier framework for designing wallets which ensure that updates increase the ledger’s global state only to a minimal extent, while preserving the security guarantees outlined in the security analysis. Third, we explore incentive-compatibility and analyze blockchain systems from a micro and a macroeconomic perspective. We enrich our cryptographic and systems' results by analyzing the incentives of collective pools and designing a state efficient Bitcoin fee function. We then analyze the Nash dynamics of distributed ledgers, introducing a formal model that evaluates whether rational, utility-maximizing participants are disincentivized from exhibiting undesirable infractions, and highlighting the differences between PoW and PoS-based ledgers, both in a standalone setting and under external parameters, like market price fluctuations. We conclude by introducing a macroeconomic principle, cryptocurrency egalitarianism, and then describing two mechanisms for enabling taxation in blockchain-based currency systems

    Socio-endocrinology revisited: New tools to tackle old questions

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    Animals’ social environments impact their health and survival, but the proximate links between sociality and fitness are still not fully understood. In this thesis, I develop and apply new approaches to address an outstanding question within this sociality-fitness link: does grooming (a widely studied, positive social interaction) directly affect glucocorticoid concentrations (GCs; a group of steroid hormones indicating physiological stress) in a wild primate? To date, negative, long-term correlations between grooming and GCs have been found, but the logistical difficulties of studying proximate mechanisms in the wild leave knowledge gaps regarding the short-term, causal mechanisms that underpin this relationship. New technologies, such as collar-mounted tri-axial accelerometers, can provide the continuous behavioural data required to match grooming to non-invasive GC measures (Chapter 1). Using Chacma baboons (Papio ursinus) living on the Cape Peninsula, South Africa as a model system, I identify giving and receiving grooming using tri-axial accelerometers and supervised machine learning methods, with high overall accuracy (~80%) (Chapter 2). I then test what socio-ecological variables predict variation in faecal and urinary GCs (fGCs and uGCs) (Chapter 3). Shorter and rainy days are associated with higher fGCs and uGCs, respectively, suggesting that environmental conditions may impose stressors in the form of temporal bottlenecks. Indeed, I find that short days and days with more rain-hours are associated with reduced giving grooming (Chapter 4), and that this reduction is characterised by fewer and shorter grooming bouts. Finally, I test whether grooming predicts GCs, and find that while there is a long-term negative correlation between grooming and GCs, grooming in the short-term, in particular giving grooming, is associated with higher fGCs and uGCs (Chapter 5). I end with a discussion on how the new tools I applied have enabled me to advance our understanding of sociality and stress in primate social systems (Chapter 6)

    Avaliação da sensibilidade de duas macrófitas de água doce ao herbicida Roundup

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    Freshwater ecosystems are home to a multitude of species that live in the aquatic environment and are an integral part of the natural communities. Among these, freshwater macrophytes are particularly important, as their functions extend beyond those commonly provided by other freshwater primary producers, creating a variety of microhabitats for other species and being an important part of the ecosystem’s structure as well. The contamination of freshwater systems by herbicides has been recognized for several decades, and is linked with the increasing trends in the use of these pesticides. Glyphosate is the most widely applied herbicide in the world, with its popularity being attributed to the development of the Roundup formulation by Monsanto, which increases the toxicity of the active ingredient to the plants by promoting its penetration into the tissues. In the present dissertation, we assessed the effects of glyphosate and its commercial formulation Roundup to the two water macrophytes, Lemna minor and Lemna gibba. To better understand the impacts these chemicals have on overall plant health, we evaluated the sensitivity of four growth-endpoints (weight, frond number, frond area, and root length), as well as the assessment of sugar profiles as biochemical endpoints, to address the knowledge gap related to non-target biochemical effects of glyphosate in plants. Results evidenced Roundup to be more toxic to both macrophytes than the active ingredient alone, as well as a higher sensitivity of L. minor compared to L. gibba. The lowest EC10 value (0.75 mg a.i. l-1) was obtained for Yield in weight of L. minor exposed to Roundup. Furthermore, root length experienced an abrupt decrease from the concentration of 1 to 3 mg a.i. l-1 in both macrophytes exposed to Roundup, and is argued to be a good bioindicator of pollution by this compound. The concentrations of the different sugars remained unaltered across the evaluated concentrations for both macrophytes, except for the sugar profiles of L. minor, which displayed a significant increase in their content of xylose, galactose, and glucose at the concentration of 5 mg a.i. l-1 of Roundup, relative to the controlOs ecossistemas de água doce alojam múltiplas espécies que habitam no ambiente aquático e formam uma parte integral das comunidades naturais. Entre estes, as macrófitas de água doce são particularmente importantes, uma vez que as suas funções vão para além daquelas comummente prestadas por outros produtores primários de água doce, criando uma variedade de microhabitats para outras espécies e sendo também uma parte importante da estrutura dos ecossistemas. A contaminação de sistemas de água doce por herbicidas tem sido reconhecida há várias décadas e é atribuída à crescente tendência no uso destes pesticidas. O glifosato é o herbicida mais aplicado à escala mundial, devendo a sua popularidade ao desenvolvimento da formulação Roundup pela Monsanto, a qual aumenta a toxicidade do ingrediente ativo para as plantas ao promover a sua penetração nos tecidos. Na presente dissertação, avaliámos os efeitos do glifosato e da sua formulação comercial Roundup a duas macrófitas aquáticas, Lemna minor e Lemna gibba. Para compreender melhor os impactos que estes químicos têm na saúde global das plantas, avaliámos a sensibilidade de quatro parâmetros de crescimento (peso, número de frondes, área das frondes e comprimento da raiz), bem como a avaliação de perfis de açúcares como parâmetros bioquímicos, de forma a colmatar a lacuna de conhecimento relacionada com efeitos bioquímicos não-alvo em plantas. Os resultados revelaram que o Roundup é mais tóxico que o ingrediente ativo para ambas as macrófitas, bem como uma sensibilidade mais elevada de L. minor comparativamente a L. gibba. O valor de EC10 mais baixo (0.75 mg i.a. l-1) foi obtido para o Rendimento de peso em L. minor expostas a Roundup. Adicionalmente, o comprimento da raiz experienciou um decréscimo abrupto da concentração 1 para 3 mg i.a. l-1 em ambas as macrófitas expostas a Roundup, colocando-se a hipótese de este ser um bom bioindicador de poluição por este composto. As concentrações dos diferentes açúcares permaneceram inalteradas para todas as concentrações avaliadas em amabs as macrófitas, com a exceção para os perfis de açúcares de L. minor, os quais apresentaram um aumento significativo no seu conteúdo em xilose, galactose e glucose para a concentração de 5 mg i.a. l-1 de Roundup, relativamente ao controloMestrado em Toxicologia e Ecotoxicologi
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