Browsing by Issue Date, starting with "2022-12-14"
Now showing 1 - 10 of 12
Results Per Page
Sort Options
- Seasonal and spatial variability of Phytoplankton primary production in a shallow temperate Coastal Lagoon (Ria Formosa, Portugal)Publication . B. Domingues, RitaCoastal lagoons are among the most productive ecosystems in the world, and they provide a wide range of ecosystem services and resources. In the Ria Formosa (southern Portugal), phytoplankton production has rarely been addressed. The main goal of this study is thus to evaluate the variability of phytoplankton production and photosynthetic characteristics over the seasonal cycle and in different locations (landward, urban, intermediate, and seaward boundaries) of the Ria Formosa coastal lagoon, subjected to distinct natural and anthropogenic stressors. Primary production was evaluated using the 14C incorporation technique, and photosynthetic parameters were estimated by fitting photosynthesis-irradiance curves. Primary production showed significant seasonal variations, with higher values in the summer associated with lower euphotic depths, higher water temperatures, and higher nutrient concentrations. No spatial differences were found for primary production or photosynthetic parameters. Primary production values were lower than previous estimates, which reflects an improvement in water quality in the Ria Formosa, but values are higher than primary production estimates for other temperate coastal ecosystems, which reflects the highly productive nature of this coastal lagoon.
- Modulating receptor activation, migration and epigenetics of cancer cells using UV lightPublication . Lourenço, Tatiana Filipa Guerreiro; Castelo-Branco, Pedro; Fernandes, MónicaCancer is a complex disease characterized by uncontrolled and unorganized proliferation caused by mutations and disruption of epigenetic processes, leading to a malignant phenotype. There are 14 main hallmarks that malignant cells share between them. This work addressed tree of such hallmarks, namely “sustaining proliferative signaling”, “enabling replicative immortality” and “non mutational epigenetic reprogramming”. In the first one, cancer cells are characterized by acquiring the capacity to sustain proliferative signaling by increasing the activation of key receptors, such as the Epidermal Growth Factor Receptor (EGFR) by its cognate ligand EGF. EGFR is a trans-membrane glycoprotein with an extracellular epidermal growth factor binding domain and an intracellular tyrosine kinase domain. EGFR regulates signaling pathways that lead to cellular proliferation and is known to be overexpressed in many cancer types, including lung cancer. Previous studies have demonstrated that photonic modulation with a wavelength of 280 nm alters the 3D structure of EGFR, preventing EGF-EGFR activation and blocking the migration of cancer cells. This wavelength is considered to be safe since it has a low probability for inducing keratitis, skin erythema and skin carcinogenesis. We treated a human lung cancer cell line, A549 EGFR Biosensor, with UV at 280 nm and 295 nm and compared to cells not exposed to UV light as controls, performing wound healing assays to evaluate the migration capacity of these cells and real time fluorescence confocal imaging of cells overexpressing EGFR to determine whether there are changes in morphology and mobility of non-luminated vs. illuminated cells at 280nm and 295nm. Our results show that both the 280nm and 295nm lengths reduce the ability of cancer cells to migrate. Also, the 280nm wavelength decreases the expression of mesenchymal markers and increases the expression of epithelial markers. Furthermore, addressing the second and third hallmark, it is known that cancer cells acquire the capability of dividing indefinitely due to the activation of telomerase, a DNA polymerase that is responsible for the maintenance of telomere length, by adding repetitive sequences at the ends of chromosomes, leading to cell immortalization. We aimed at halting “enabling replicative immortality” and “non mutational epigenetic reprogramming” using the same photonic approach and to investigate if the light assault led to epigenetic changes and possible modulation of the telomerase expression/activity. In addition, we performed RT-qPCR to verify if there is an association between the expression of EGFR and Telomerase Reverse Transcriptase (hTERT)) and found that hTERT expression appears to be altered by radiation when cells were exposed for 30min and harvested at 0h, 24h and 48h. Moreover, we carried out pyrosequencing assays to understand if radiation is involved in epigenetic mechanisms, through altering DNA methylation patterns in a specific promotor region of hTERT. Our data shows that cells irradiated for 30 minutes present a significant reduction in DNA methylation at the studied region and that this pattern is maintained for 24h. Since metastases represent the main cause of death in cancer patients, our data proves to be promising in the development of a new treatment in the future, that improves the quality of life of patients and prevents metastatic progression.
- Exploring cellulose as raw material in the production of a coagulant/flocculant for wastewater treatmentPublication . Ismail, Abdullah; Costa, Ana M. Rosa da; Teixeira, Margarida RibauCellulose, the most prevalent natural biopolymer on earth, may provide an efficient, environment-friendly, inexpensive, and chemical-free solution for water and wastewater treatment. Cellulose-based materials are utilized in the food industry, pharmaceutical, paper textile industries, and wastewater treatment due to their low cost, renewability, biodegradability, and nontoxicity. This study aims to explore cellulose as raw material to produce coagulants to remove turbidity from wastewater. All the synthesized coagulants and a commercial coagulant, for reference purposes, were tested in jar test experiments using synthetic wastewater with a turbidity of 92-96 NTU and real urban wastewater with a turbidity of 142-156 NTU. Cellulose extracted from powdered pine needles was modified by reductive amination after the periodate oxidation, showed no turbidity removal during the jar test. Cellulose from filter paper was processed by 2,2,6,6- tetramethyl-4-acetamidopiperidin-1-oxyl (TEMPO) oxidation and examined to assess its coagulation performance, which did not show the desired activity. Finally, three different micro/nanofibrillated cellulose (M/NFCs) derivatives cationized with 3-chloro-2-hydroxypropyltrimethyl ammonium chloride (CHPTAC) and with carboxymethyl trimethyl ammonium chloride hydrazide (Girard’s T reagent), as well as anionized by TEMPO oxidation were analyzed. CHPTAC-treated samples showed excellent removal of turbidity, which was close to the performance of polyaluminium chloride commercial-grade (WAC-AB®) coagulant. MFCs (treated with CHPTAC) with a higher degree of substitution (DS 0.106) showed 93.2% turbidity removal for synthetic wastewater and 85.7% for real urban wastewater, while that with a lower degree of substitution (DS 0.06) showed 91.0% and 58.9% removal for turbidity in synthetic and real wastewater, respectively.
- Optimal deployment of mobile gateways in LoRaWAN environmentsPublication . Mendes, Bruno Eusébio; Correia, N.; Passos, DárioThe recent growth of the Internet of Things (IoT) has given rise to new applications and technologies. Of these technologies, LoRa is the one that has stood out recently due to its ability to transmit packets over long distances at low energy costs. In addition to this, this technology also uses unlicensed frequency bands, and all these factors make it possible to build low energy cost networks with large coverage areas at low monetary cost. This makes LoRa very appealing for environments where multiple square kilometers need to be covered for monitoring, such as agriculture. This thesis focuses primarily on positioning gateways in a Lo- RaWAN in order to achieve energy fairness in the network.The target in question is an environmental sensor network that monitors conditions inside tree canopies in an orange orchard in the Algarve, south of Portugal.The peculiar characteristics of these orange trees, with heights up to 3.5 m and very dense foliage, makes it a very challenging environment for radio waves propagation and causes a rapid drop in signal quality. The power consumption of the end-nodes of the network is defined by 7 combinations of spreading factor and bandwidth (0 to 6) where 0 represents the slowest and most reliable transmission at the cost of higher power consumption while 6 represents the opposite. The combination of bandwidth and spreading factor is denominated data rate. Environmental factors can negatively impact the quality of LoRa packets and the necessary power adjustments of the end-node to overcome this, and increase signal reliability, can easily define whether a device is able to transmit for 1 year or 10! The main factors that can affect signal quality are obstruction, distance and meteorology. In the case study, of these 3 factors, obstruction affects transmission quality the most. Most of the literature suggests solutions within the framework of optimizing the datarate optimization algorithm (ADR). ADR aims to minimize energy consumption while ensuring the best possible packet transmission rate and achieves this by changing the data rate based on the quality of the last 20 packets received.However, this optimization is done directly to individual end-nodes and does not solve the problem of energy fairness over the whole network because, regardless of how optimized this algorithm is, the algorithm cannot transcend the physical constraints imposed by the devices and the technology itself. Distance and obstruction will always be obstacles to signal quality. Since these physical constraints will always be present in a network and the solutions proposed by the literature only improve performance at the level of individual devices, this ends up creating a large lifetime discrepancy between devices depending on their placement. In the case of LHT65s, the discrepancy in device life expectancy is high. For example the difference between using a data rate of 0 or 5 is about 10 years. The solution proposed in this thesis to overcome this problem is to precompute the optimal position for the gateways in order to guarantee the highest life expectancy for the network. Given a number of available positions for the gateways and having a certain number of gateways less than the number of positions, the goal is to compute the optimal positioning of the gateways in order to maximize the overall network life expectancy by ensuring a fair energy consumption among different end-nodes. The first step in this process was to collect information about signal quality from a real case LoRaWAN deployment. This allowed to better understand the constraints and problems associated with its implementation. This was done using 25 LTH65 devices, 1 RAK 7244 gateway and Chirpstack as the framework to manage the network. Regarding the study of the algorithm before applying it to the practical case, a simulator was used to collect data. The simulator chosen for the development of the application was OMNet++, which besides being easier to use is also better documented than the other options considered. This simulator also offers a graphical interface with great detail that allows you to easily observe the behavior of the network. Using the Flora module it was simulated a LoRaWAN network with the structure suggested by the LoRa Alliance® with 25 devices using Oulu’s path loss model. The information obtained from this simulation was used as input and test for the algorithm that was compiled by CPLEX. In each simulation about 10,000 packets were sent per device and each experiment was repeated 30 times. The results show that the optimization model has the ability to identify the best placement for the gateway given a predefined locations and network geometry. This is due to the fact that the algorithm identifies the lowest value in the highest energy consumption per packet, and minimizing this value creates a balance of consumption among the devices and consequently extends the life expectancy of the network. It can then be concluded that this methodology is indeed efficient for deployments where changing network devices cannot be done frequently. Although it is not easy to relocate gateways in already implemented networks, but in new environments where monitoring and optimization are requirements, and these new environments are built considering the network structure, we can use this methodology since it has proven to be able to improve network life expectancy.
- The becoming of a Prehistoric Landscape: Palaeolithic Occupations and Geomorphological Processes at Lojanik (Serbia)Publication . Lesage, Camille; Barbieri, Alvise; Galfi, Jovan; Jovanović, Dragan; Bogosavljević Petrović, VeraAccomplishing long-term plans to harvest and modify natural resources has been a crucial skill for the survival of our species since early Prehistory. Research on this first step of production mostly focuses on the provenience study of lithic artifacts uncovered at archaeological sites, using petrographic and geochemical analyses to correlate the artifacts with potential geological outcrops. Although fundamental for understanding key aspects of landscape use and mobility, regional raw material economy, and extraction technology, Palaeolithic raw material sources have been less intensively investigated, as they are often difficult to locate and challenging to tackle with traditional archaeological approaches. Lojanik in the Central Balkans is one of the largest Prehistoric quarrying areas known in Europe, showing numerous lithic raw material outcrops exploited from the Middle Palaeolithic to the Chalcolithic periods, over an area of 18 hectares. In this paper, we present the results from our renewed research program in this region. Combining airborne LIDAR mapping, geomorphological and archaeological survey, and techno-typological analysis of lithic artifacts, we were able to reconstruct the geomorphological evolution of the landscape and its use by prehistoric societies.
- O papel do farmacêutico comunitário na sensibilização da comunidade para o uso de protetor solarPublication . Nascimento, Catarina Vanessa Gonçalves; Condinho, Mónica Sofia LealA radiação ultravioleta representa 5 a 10% da radiação solar que atinge a Terra. É a mais energética e é dividida na radiação ultravioleta do tipo A, B e C. Se a exposição ao sol for, a longo prazo, desprotegida e intensa, pode originar cancro de pele, queimaduras solares e fotoenvelhecimento da pele. Deste modo, torna-se importante a sensibilização da população, pelos profissionais de saúde, para a adoção de medidas de fotoproteção, nomeadamente, para a correta utilização de protetor solar (formulação tópica que protege a pele e que inclui filtros orgânicos e/ou inorgânicos). A intervenção do farmacêutico em várias campanhas de sensibilização e de educação da população neste âmbito, tem sido, aparentemente, positiva. Assim, com o objetivo de avaliar o conhecimento da comunidade em relação ao uso de protetor solar e estudar o papel do farmacêutico na sensibilização para o uso do mesmo, procedeu-se, durante 5 semanas, à realização de um estudo em farmácia comunitária. Neste estudo, 58 voluntários, selecionados de forma oportunística, preencheram um questionário autoadministrado com 14 perguntas. A partir da análise dos resultados, verificou-se que a maioria dos inquiridos tem um elevado nível de conhecimento na área da fotoproteção, no entanto, existe alguma falta de informação e de consciencialização para o uso diário de protetor solar. Salienta-se, também, que os participantes consideraram que o aconselhamento farmacêutico é importante na escolha do protetor solar, bem como na sensibilização da população em relação às medidas de proteção solar. Conclui-se, assim, que a intervenção do farmacêutico, neste âmbito, é positiva, nomeadamente durante a escolha do protetor solar e na sensibilização da população através da partilha de minutos informativos; da execução de ações de sensibilização à comunidade; e da publicação de folhetos informativos sobre o uso de protetor solar.
- Metais de transição e o sistema nervoso central: toxicidade, uso em diagnóstico e opções terapêuticasPublication . Augusto, Beatriz Maria Gil; Lourenço, J. P.Desde a revolução industrial, as doenças agudas ou crónicas resultantes da exposição a metais pesados têm vindo a aumentar gradualmente. Em humanos, o Sistema Nervoso Central (SNC) e o Periférico (SNP) encontram-se entre os sistemas que são mais impactados pela bioacumulação de metais pesados, sendo os danos bastante significativos e bem documentados. Estes danos incluem deficiências mentais, neurológicas e cognitivas. Os metais essenciais como o cobre (Cu) ou o zinco (Zn), são fundamentais para o bom funcionamento a nível bioquímico e fisiológico do ser humano. Assim, o inadequado fornecimento dos mesmos (acima ou abaixo dos níveis homeostáticos), poderá levar à função aberrante do SNC, e consequentemente, ao surgimento de várias doenças, síndromes e/ou efeitos adversos. Já no caso do mercúrio (Hg) ou do chumbo (Pb), visto não terem função biológica estabelecida, são denominados de metais não essenciais, sendo que a sua acumulação é bastante prejudicial para o bom funcionamento do organismo. O excesso de metais essenciais ou a presença de outros metais não essenciais no organismo exige tratamento adequado, sendo a terapêutica quelante o tratamento primário para a intoxicação de metais pesados. Por outro lado, alguns metais são úteis em medicina de diagnóstico, já que inúmeras patologias neurodegenerativas beneficiam, no que diz respeito à deteção, do uso da ressonância magnética, como o caso da doença de Parkinson (DP). Sendo o SNC um dos sistemas de órgãos que sofre de forma mais significativa com a alteração da homeostasia de metais pesados, é difícil negar o papel importante que estes metais apresentam a nível biológico no ser humano. Assim, a presente monografia tem como objetivo a análise sistemática da literatura científica no que diz respeito à função de alguns dos metais de transição (essenciais e não essenciais) no SNC, incluindo as doenças/ síndromes ou efeitos adversos associados ao desequilíbrio da homeostasia destes, a sua importância a nível de diagnóstico e as opções terapêuticas no sentido de restabelecimento dos equilíbrios biológicos.
- Cucurbiturilos como contentores moleculares: Estratégias de encapsulação de endoperóxidos com atividade antimaláricaPublication . Struk, Anna; Lopes, André D.; Cristiano, Maria Lurdes SantosNo desenvolvimento de fármacos um dos principais desafios corresponde à criação de formulações estáveis que consigam alcançar o alvo terapêutico in vivo. Além da formulação de novos fármacos, o encapsulamento dos já existentes em contentores moleculares representa uma das estratégias utilizadas para otimizar a resposta terapêutica e minimizar os efeitos adversos. Alguns sistemas macrocíclicos têm sido explorados como contentores moleculares, evidenciando capacidade para encapsular agentes terapêuticos através de interações não covalentes. Os cucurbiturilos, de abreviatura CB[n], surgiram recentemente como uma nova classe de contentores moleculares capazes de encapsular uma grande variedade de moléculas, incluindo corantes fluorescentes, fármacos e moléculas biológicas. A malária é uma doença infeciosa causada por parasitas do género Plasmodium, transmitidos ao ser humano através da picada de mosquitos fêmea do género Anopheles, afetando principalmente áreas tropicais e sub-tropicais. São conhecidas 5 espécies de Plasmodium que infetam o ser humano, sendo P. vivax e P. falciparum responsáveis pela quase totalidade dos casos de malária, a nível mundial. Dados da OMS indicam que, em 2020, o número total de casos de malária rondava 241 milhões e o número de mortes por malária foi de ca. 627.000, um aumento de ca. 69.000 mortes em relação ao ano anterior. Este facto é atribuído, essencialmente, ao desenvolvimento de resistências pelo parasita aos fármacos antimaláricos em uso, incluindo às terapêuticas de primeira linha baseadas em artemisinina. Assim, é urgente o desenvolvimento de terapêuticas com propriedades farmacológicas melhoradas, nomeadamente com eficácia contra estirpes de P. falciparum resistentes. Posto isto, a presente dissertação aborda o potencial dos cucurbiturilos para o encapsulamento de endoperóxidos com atividade antimalárica. Na primeira parte apresenta-se uma revisão bibliográfica sobre a utilização de cucurbiturilos na encapsulação de fármacos. Na segunda parte descreve-se o trabalho experimental realizado, versando a síntese de um endoperóxido com propriedades antimaláricas e a sua encapsulação em CB[7], incluindo resultados preliminares de estudos in vitro da atividade antiplasmodial.
- Genetic diversity within a wild rocket [Diplotaxis tenuifolia (L.) DC.] germplasm collection and molecular characterization of selected accessionsPublication . Reis, João Pedro Martins dos; Leitão, J. M.; Coelho, Maria Paula Mesquita dos SantosWild rocket (Diplotaxis tenuifolia (L.) DC) is a species known for its growing consumption as “baby leaf” crop. Downy mildew, a disease caused by the pathogen Hyaloperonospora sp., is one cause of production losses in D. tenuifolia cultivation. To preserve elevated quality standards and sustainable production of wild rocket, the characterization of genetic diversity present in a germplasm collection is an important step towards the identification of genetic resources, fundamental to plant breeding. The objectives of this work encompass the characterization of the genetic diversity within a germplasm collection of D. tenuifolia, including a set of E. sativa samples, and the unequivocal identification of a group of selected accessions, using molecular markers. Genetic diversity analysis, performed using 5 Inter Simple-Sequence Repeats (ISSR) and 7 Random Amplified Polymorphic DNA (RAPD) primers, resulted in 110 scorable polymorphisms. Wild rocket accessions exhibited intraspecific genetic similarity with values ranging between 0.697 and 0.994. Tighter clusters aggregate accessions with greater genetic similarity provided by the same producing company. The unequivocal identification of 90 accessions was performed using Simple-Sequence Repeats (SSR) and Single Nucleotide Polymorphisms (SNP) markers, the latter analyzed as Cleaved Amplified Polymorphic Sequences (CAPS). These loci were mined from the D. tenuifolia genomic assembly (UAlgDiploT.01), uploaded to the genomic databases. Twenty SSR and 19 SNP loci (selected by the presence of a TaqI restriction region in the SNP site), were retrieved for analysis. From this, five SSR and nine SNP loci were selected, giving rise to 70 SSR alleles analyzed by capillary gel electrophoresis and 36 CAPS polymorphisms. The molecular characterization of selected accessions resulted in the identification of specific fingerprints for the accessions, excluding 1 trio and 6 pairs of wild rocket accessions, exhibiting full similarity (100%). Thus, confirming the presence of duplicate accessions provided by different breeding and commercial companies.
- Impact of temperature on Phenolic and Osmolyte contents in In Vitro cultures and micropropagated plants of two mediterranean plant species, Lavandula viridis and Thymus lotocephalusPublication . Mansinhos, Inês; Gonçalves, Sandra; Rodríguez Solana, Raquel; Ordóñez-Díaz, José Luis; Moreno-Rojas, José Manuel; Romano, AnabelaIn this study, in vitro cultures and micropropagated plants of two Mediterranean aromatic plants, Lavandula viridis L’Hér and Thymus lotocephalus López and Morales, were exposed to different temperatures (15, 20, 25, and 30 ◦C). The effect of temperature on the levels of hydrogen peroxide (H2O2 ), lipid peroxidation, and osmoprotectants (proline, soluble sugars, and soluble proteins), as well as on the phenolic profile by HPLC-HRMS and intermediates of the secondary metabolism (phenylalanine ammonia lyase (PAL) activity and shikimic acid content), was investigated. Moreover, the antioxidant activity of the plant extracts was also analyzed. Overall, considering the lipid peroxidation and H2O2 content, the extreme temperatures (15 and 30 ◦C) caused the greatest damage to both species, but the osmoprotectant response was different depending on the species and plant material. In both species, phenolic compounds and related antioxidant activity increased with the rise in temperature in the micropropagated plants, while the opposite occurred in in vitro cultures. L. viridis cultures showed the highest biosynthesis of rosmarinic acid (92.6 g/kgDW) at 15 ◦C and seem to be a good alternative to produce this valuable compound. We conclude that contrasting temperatures greatly influence both species’ primary and secondary metabolism, but the response is different depending on the plant micropropagation stage.