Browsing by Issue Date, starting with "2023-03-13"
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- O papel de TRIB2 na autofagiaPublication . Bento, Alexandra Diogo; Ferreira, Bibiana; Link, WolfgangO cancro é uma das principais causas de morte no mundo. As células cancerígenas beneficiam de processos celulares como a autofagia para sobreviver a condições de stress no seu microambiente, como privação de nutrientes, baixos níveis de energia e hipóxia. Em vários tipos de tumor a via de PI3K/AKT está hiperactiva, o que permite que a cinase mTOR, regulador da proliferação celular, apoptose e regulador negativo da autofagia, esteja ativo. Na quimioterapia convencional são utilizados inibidores de mTOR e PI3K/AKT, que consequentemente ativam a autofagia, o que resulta na sobrevivência das células cancerígenas e resistência aos tratamentos. A proteína TRIB2 é uma pseudocinase descrita como um oncogene que favorece a ativação da via de PI3K/AKT. É um membro da família TRIBBLES que inclui TRIB1 e TRIB3. Previamente foi publicado por diferentes grupos de investigação que a sobreexpressão de TRIB3 parece ter em vários contextos tumorais uma ação oposta à exercida por TRIB2, conferindo características de gene supressor de tumor. No contexto autofágico, TRIB3 parece suprimir a indução da autofagia conferindo às células acumulação de fatores promotores de tumor. Tendo em conta estes dados, propusemos estudar o papel de TRIB2 no processo autofágico. Sabendo que TRIB2 e TRIB3 parecem exercer em determinadas circunstâncias papéis antagónicos, a nossa hipótese é que tumores com elevados níveis de TRIB2 levariam a um aumento no fluxo autofágico. Os nossos dados demonstraram que células com sobreexpressão de TRIB2 apresentam níveis reduzidos de expressão de genes autofágicos. A análise de autofagossomas e autolisossomas por microscopia confocal permitiu concluir que a dinâmica do fluxo autofágico é menor em células que sobreexpressam TRIB2. Quando analisámos o impacto da presença de TRIB2, quando a autofagia está bloqueada, verificaram-se níveis elevados de morte celular, o que indica que células com TRIB2 são mais vulneráveis ao bloqueio da autofagia. Assim, concluímos que a nossa hipótese é refutada e que TRIB2 inibe o fluxo autofágico. O nosso estudo contribui para o conhecimento de TRIB2 na autofagia, e vem reforçar a importância deste biomarcador tumoral na terapêutica de tumores com elevados níveis de TRIB2. No entanto é necessário explorar o mecanismo pelo qual a proteína TRIB2 inibe a autofagia. Em suma, pacientes com elevados níveis de TRIB2 podem beneficiar de compostos que inibam diretamente a via de PI3K/AKT e o fluxo autofágico.
- Photography, Land-Cover and Land-Use changes, and tourism urbanization: A narrative focused on Hotel do Garbe, Armação de Pêra, Algarve, PortugalPublication . Loureiro, Nuno de SantosThis article is focused on the use of photography to characterize land-cover and land-use changes in a 7.59 km2 study area centered on Hotel do Garbe, in the village of Armação de Pêra, Algarve, Portugal. Orthorectified vertical aerial, oblique aerial and ground-level photographs were the main data sources required to carry out the analysis. In a preliminary approach, a conventional research design was adopted. Based on the available orthorectified vertical aerial photographs, a sixty-year time series, with four homogeneously distributed steps (1958, 1978, 1997 and 2018), was constructed, and maps were produced to support the description of the changes that have taken place. To deepen the analysis, photographs from fourteen picture postcards were recognized as a useful source of information, and the authors of these photographs were considered “involuntary or accidental photo-geographers” whose work was relevant to feed a case study in which human geography and landscape biography sciences are the main narrative axes. The final result proved to be richer than the interpretation only based on the orthorectified vertical aerial photographs, and the importance of combining photographs taken from different points of view, with different aims and for different recipients is highlighted.
- Factors affecting green turtle (Chelonia mydas) hatching success, and their temporal variation over 7 study yearsPublication . Plank, Karin; Vinagre, Catarina; Hughes, MorganSea turtles are considered one of the most important key species in marine ecosystems, leading top-down regulations in food-webs, transferring nutrients and functioning as sentinel-species for monitoring effects of climate change. However, heavy exploitation over years due to the trade and consumption of turtle meat and their eggs, and the challenges faced by climate change, have resulted in a concerning global population decline of sea turtles. On Playa Norte, Costa Rica, in the surrounding area of Tortuguero, which gives nesting habitat to the largest green turtle (Chelonia mydas) population of the Atlantic Ocean, the main threats for turtle eggs and hatching success are poaching, predation by dogs, erosion and flooding, overheating and microorganisms. This study examined if the relative impact of each cause changes within a nesting season, and if occurrences have a constant trend over a study period of 7 years. A local study of the seasonality of each impact could endorse the development of effective conservation actions and an adjusted management plan that can be applied strategically to each cause expected at a certain time of the year. Hatching success averaged 38.65% for the 7 study years and was not significantly different among years, nor between climatic periods within a nesting season. Primary reasons for egg loss were “poaching” (24.72%) and “dog predation” (18.11%), followed by natural predation (3.81%), temperature (3.59%), flooding (3.51%), moisture/wet (3.22%), erosion (2.89%) and maternal effects (1.50%). The impact of causes of egg loss were largely constant over the study period. Factors related to climate and weather generally displayed high fatality but a low number of occurrences. On the other hand, anthropogenic factors accounted for the highest turtle egg mortality aggregating both impact and number of events. In terms of seasonality, not all of the causes displayed significant differences between periods, however all causes reached their highest impact in period 3. This suggests that the focus of conservation actions on Playa Norte should be put on the months between September and December, with particular emphasis on anthropogenic factors rather than environmental stressors. An intensification of beach patrol in this period, and nest reburial into an enclosed hatchery are recommended to increase hatching success and ensure recruitment for this green turtle population.