Browsing by Issue Date, starting with "2021-07-29"
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- Optimization of management procedures for sea urchin (paracentrotus lividus) artificial reproductionPublication . Rodrigues, Daniel Alexandre Cardoso; Cabrita, Elsa; Soares, FlorbelaAquaculture industry has a huge contribution for the world food production, and is extremely necessary to develop and optimize the production techniques, especially not to depend totally on wild stocks. In the case of the sea urchin Paracentrotus lividus, the demand increase of their roe is provoking a drastically decrease of their wild stocks, particularity in the recent years. This demand for sea urchin roe is arousing interest for the industry for a new profitable product and for the recovering and preserve wild populations. In this sense, new research needs to guarantee optimization of the techniques used to reduce the effort and the production cost. The selection of breeders is a very important aspect for sea urchin industry, since the success of the reproduction and quality of their product are dependent of the breeders. In addition to the high cost of acquiring wild specimens, it is not viable in the long term. Therefore, is important to study the possibility of use breeders from captive generations. The optimization of in vitro reproduction techniques is crucial for an efficiency production. The time that gametes need to be in contact for the best fertilization rate and the ratio of spermatozoa per oocyte are two of the principal aspects to be considered in an optimization of an in vitro reproduction protocol. Through preservation and cryopreservation technology is possible to promote alternatives techniques to contribute for the resource management efficiency of P. lividus. The objectives of this work are to study the hypothesis of using male wild sea urchins from different locations and captive generations specimens as breeders, optimize in vitro protocols using different contact times and different spermatozoa to oocyte ratio, and compare cryopreservation and preservation techniques for the storage of the sperm. To study the possibility of use captive generations as breeders were evaluated the sperm quality of each case, for this evaluation were analyzed the viability and motility, being used two approaches for the last one (mean values and subpopulation). The optimization of fertilization outcomes was evaluated counting the number of fertilized eggs using a counting chamber (Sedgwick) in optical microscope. Moreover, the comparation of the preservation and cryopreservation techniques was analyzed the motility by mean values, viability and DNA fragmentation (comet assay). The motility analysis were assessed by CASA system, viability through staining techniques and counting at a fluorescent microscope, DNA fragmentation was quantified the DNA tail. Significant differences were observed (p<0.05) in breeders selection, revealing the domestication seems to have a positive effect in P. lividus sperm quality. The in vitro spermatozoa to oocyte ration trial reveled significant differences between all ratios, where the 20 000 spermatozoa to oocyte ratio had the higher value. Contact times chosen differed negatively from the control. The preservation technique had higher viability in the first 6 days comparing to cryopreservation, although had no damage in DNA were detected in both. The present study revealed that domestication seems to be a good step to optimize the breeders sperm quality. With the higher spermatozoa to oocyte ratio used is possible to reach almost the total egg fertilization percentage. The preservation at 4ºC is a good technique to preserve the sperm quality until 6 days, cryopreservation seems to be better from there if the protocol is optimized.
- Fitoterapia no tratamento da patologia da gotaPublication . Portugal, Francisca Gouveia; Miguel, Maria GraçaA gota é uma doença reumática desencadeada pela resposta inflamatória à deposição e acumulação de cristais de monourato de sódio, que se pode desenvolver em indivíduos com níveis séricos elevados de ácido úrico (hiperuricémia) devido à sua superprodução ou deficiente eliminação renal e ou intestinal. Para que seja considerado gota, e não apenas hiperuricemia, exige a manifestação dos sintomas típicos da resposta inflamatória. Nas últimas décadas é possível verificar um aumento da prevalência da gota. Atinge entre 1-4 % dos adultos em todo o mundo e em Portugal, estima-se que afete 1,6% da nossa população. Apesar da inquestionável eficácia das alternativas terapêuticas existentes atualmente no mercado farmacêutico, a evidência científica descortinou efeitos adversos severos. Em contrapartida, a comunidade científica alega a existência de um leque diversificado de plantas com aplicação quer na prevenção quer no tratamento da gota, seja pelo seu uso empírico, seja porque a sua efetividade foi avaliada in vitro e/ou in vivo, baseando-se no seu potencial de inibição sobre a xantina oxidase (XO), na sua ação uricosúrica ou pelo seu efeito antiinflamatório e antioxidante. O presente trabalho que é uma revisão bibliográfica com recurso a ferramentas como a PubMed e a guidelines terapêuticas indicadas para a gota, começa pela definição, evolução histórica, classificação, epidemiologia, patogenia e manifestações clínicas desta patologia. De seguida, apresenta a terapia convencional geralmente dirigida para a gota, focando-se depois nos estudos que utilizam as plantas, quer em estudos in vitro quer em estudos in vivo, com potencial ação farmacológica nesta doença. O contributo do farmacêutico no tratamento da gota é igualmente abordado bem como a necessidade da farmacovigilância em Produtos à Base de Plantas.
- Phytoplankton dynamics off southern Portugal: a physical-biological approachPublication . Lima, Maria João Borlido Oliveira; Barbosa, Ana B.; Relvas, PauloIdentifying the environmental drivers of phytoplankton blooms, especially harmful algal blooms, has become imperative for forecasting these events. This study aimed to evaluate phytoplankton variability patterns, phenology and underlying environmental determinants within specific regions off southern Portugal, during a 6-year period (2014-2019). Phytoplankton phenology was assessed using region-specific chlorophyll-a concentration (Chl-a) and abundance of phytoplankton taxa, responsible for amnesic (ASP), diarrhetic (DSP) and paralytic shellfish poisoning (PSP), and relationships between abiotic environmental variables and phytoplankton were explored using Generalized Additive Models (GAM). Over oceanic regions, Chl-a showed a unimodal annual cycle, with increases during the mixed layer deepening phase and late-winter to early-spring maxima. The slope and coastal regions showed an additional summer peak, related with local upwelling, more prominent for the west coast. The development of a coastal counter-current that probably transports riverine nutrients and phytoplankton biomass, might have also contributed for Chl-a increase over the south coast. GAM explained from 14% to 77% of Chl-a variance, with higher explanatory power for oceanic and coastal regions under riverine influence. Sea surface temperature, photosynthetically available radiation, and mixed layer depth emerged as the most influential predictors, and large-scale climate indices showed minor effects. ASP-producing species showed a bimodal annual cycle for most coastal production areas, with first bloom onset in spring, and peak timing during late-spring and summer, associated with upwelling conditions that favour diatom blooms. DSP and PSP-producers exhibited a unimodal annual cycle, peaking during late-summer and late-spring, respectively, during upwelling relaxation periods. DSP models explained between 21% and 54% of the deviance, whereas ASP models revealed a weaker performance (7-8%). In addition to the referred Chl-a predictors, high river discharges exerted a negative influence on both ASP- and DSP-producers. Downwelling/countercurrent regimes globally favoured DSP-producers, while upwelling promoted ASP-producers only over the most southeastern coastal area. Future predictions of harmful phytoplankton blooms for the area should then consider the identified influential predictors but must be complemented with additional environmental variables, and explore specific periods (e.g., seasons, extreme events) and hybrid modelling approaches.
- Role of neuronal cholesterol in peripheric metabolic tissuesPublication . Castro, Telma Cristina Aureliano; Nóbrega, Clévio; Coelho, Ana Luísa De SousaThe brain possesses 20% of whole-body cholesterol, becoming the richest cholesterol organ in our body. Due to the Blood Brain Barrier, the cholesterol has its own way to synthesize and degrade cholesterol, in order to maintain its homeostasis. Cholesterol is synthesized through de novo synthesis in the brain and transported out of the brain in the form of oxysterols, more specifically 24-hydroxycholesterol (24-OHC). This process is acomplished through CYP46A1, a protein of the CYP450 family. Alterations in cholesterol homeostasis can lead to metabolic abnormalities, such as obesity, inflammation and insulin resistance. Previous studies in our laboratory showed that alterations in the expression of Cyp46A1 gene (more specifically silencing) with different diets, rich and poor in fat, had impacts in whole-body homeostasis. Taking these results into account, the main objective of this study was to evaluate the impact of modulation of Cyp46A1 gene in the main metabolic organs (liver, pancreas, and adipose tissue), through silencing and overexpressing CYP46A1 in the arcuate nucleus of the hypothalamus. This modulation was made in C57BL/6J mice fed with two distinct diets, one rich in fat (HF diet) and one poor in fat (CHOW diet). The data obtained from microscopy and tissue quantification made it possible to see the physiological changes resultant from the modulation of CYP46A1. It was possible the phenomenon BAT “whithening”, an increase in the size of Langerhans islets and lipidic hypertrophy. RT-qPCR was also realized to evaluate the mRNA levels of the different targets in the hypothalamus. The results obtained from RT-qPCR, showed that modulation of Cyp46A1 affected the mRNA levels of the different targets tested (POMC, NPY and TNF-alpha). All this data confirmed our hypothesis, that the modulation of CYP46A1 do alter the whole-body metabolism. Further studies must be conducted to continue this project, in order to investigate if this gene could be a target for genetic therapies.