Browsing by Issue Date, starting with "2018-03-12"
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- Acoustic methods for assessment of bubbles produced by marine plantsPublication . Silva, João Pedro Santos Parente da; Felisberto, P.; Silva, AntónioThe aim of this dissertation is to evaluate different acoustic methods to characterise air bubbles and their application in the estimation of oxygen bubbles produced by marine plants during the photosynthesis process. Several methods are described in the literature to estimate the amount and distribution of air bubbles in marine waters however, the existing methods focus essentially on bubbles at the ocean’s surface. Under certain conditions, the oxygen released by marine plants during photosynthesis occurs in the form of bubbles. The estimation of this bubbles is difficult and is often considered underestimated by conventional methods. Acoustic methods can be used to estimate the production of bubbles with greater precision and, moreover, to learn the dynamics of their production. It is necessary to evaluate the oxygen transfer process of the plants to the water, the model of acoustic propagation in seagrass fields, the configuration of the system, methods to filter the influence of unwanted parameters on the received signal (e.g., temperature changes, noise, tide, sound speed, salinity), and, to characterise environmental and biological noise. In this work, I propose to evaluate a suitability and generic bubble estimation method described in the literature, or the development of new methods for the monitoring of bubbles released by marine plants, in particular, seagrass Cymodocea Nodosa. The reliability of a generic bubble estimation method described in the literature, as well as, new methods for monitoring the bubbles released by marine plants will be tested. All the tests were conducted with the Cymodocea Nodosa seagrass species, in tanks on IPMA-EPPO. Combining acoustic with other techniques (CTD data, tide height) will allow the development of a robust and accurate acoustic measurement system. The acquired signals can be processed to estimate the amount of oxygen bubbles produced in that environment. With the use of this measurement system, I believe that this innovative acoustic method can be used to accurately quantify the ecosystem metabolism and that it will represent an important tool to manage and monitor the production of coastal areas by integrating spatial and temporal scales.
- Mechanisms of human telomerase reverse transcriptase (hTERT) regulation: clinical impacts in cancerPublication . Leão, Ricardo; Apolónio, Joana; Lee, Donghyun; Figueiredo, Arnaldo; Tabori, Uri; Castelo-Branco, PedroBackground Limitless self-renewal is one of the hallmarks of cancer and is attained by telomere maintenance, essentially through telomerase (hTERT) activation. Transcriptional regulation of hTERT is believed to play a major role in telomerase activation in human cancers. Main body The dominant interest in telomerase results from its role in cancer. The role of telomeres and telomere maintenance mechanisms is well established as a major driving force in generating chromosomal and genomic instability. Cancer cells have acquired the ability to overcome their fate of senescence via telomere length maintenance mechanisms, mainly by telomerase activation. hTERT expression is up-regulated in tumors via multiple genetic and epigenetic mechanisms including hTERT amplifications, hTERT structural variants, hTERT promoter mutations and epigenetic modifications through hTERT promoter methylation. Genetic (hTERT promoter mutations) and epigenetic (hTERT promoter methylation and miRNAs) events were shown to have clinical implications in cancers that depend on hTERT activation. Knowing that telomeres are crucial for cellular self-renewal, the mechanisms responsible for telomere maintenance have a crucial role in cancer diseases and might be important oncological biomarkers. Thus, rather than quantifying TERT expression and its correlation with telomerase activation, the discovery and the assessment of the mechanisms responsible for TERT upregulation offers important information that may be used for diagnosis, prognosis, and treatment monitoring in oncology. Furthermore, a better understanding of these mechanisms may promote their translation into effective targeted cancer therapies. Conclusion Herein, we reviewed the underlying mechanisms of hTERT regulation, their role in oncogenesis, and the potential clinical applications in telomerase-dependent cancers.