5 resultados para Rato como animal de laboratório Teses
em Repositório Institucional da Universidade de Aveiro - Portugal
Resumo:
Apesar da fauna de mamferos Neotropicais ser uma das mais ricas do mundo, o nosso conhecimento sobre os limites de espcies, distribuies geogrficas e relaes filogenticas est ainda agora no seu incio. As reas de transio entre os dois maiores biomas da Amrica do Sul, o Cerrado e a Amaznia, so ainda menos conhecidas. At ao momento, escassos estudos focaram os pequenos mamferos destas reas. Destes estudos, apenas dois apresentam dados taxonmicos e de distribuio geogrfica de uma lista de espcies reduzida e, nenhum focado nos processos evolutivos que conduziram diversidade destas reas. O presente trabalho tem como objectivo aumentar o conhecimento bsico sobre a diversidade do mdio Rio Araguaia, na regio central do Brasil, atravs da amostragem e anlise de espcies de pequenos mamferos, integrando um intenso trabalho de campo, de laboratório e de museu. Desta forma, um total de 22 espcies registado para o mdio Araguaia. De entre estas espcies, descreve-se uma espcie nova de Rhipidomys, regista-se uma espcie no descrita de Thrichomys e uma potencial nova forma de Oligoryzomys, e tambm se apresenta uma diagnose emendada do obscuro Oecomys cleberi. Para cada espcie, so tambm descritas as suas caractersticas morfolgicas e resumem-se os seus aspectos de distribuio geogrfica e histria natural. Para os quatro gneros acima referidos, so apresentadas as anlises filogenticas que permitem a identificao das espcies. Adicionalmente, os princpios da filogeografia so aplicados para estudar os padres da distribuio geogrfica da diversidade gentica de trs roedores sigmodontneos e seis marsupiais didelphdeos. Os resultados obtidos demonstram que o Rio Araguaia forma uma barreira geogrfica para espcies especialistas em florestas no-alagveis; por outro lado, espcies generalistas apresentam partilha de hapltipos em ambas as margens do rio. Argumentamos tambm que os refgios florestais e os gradientes podero ter tido um papel importante para moldar a estrutura gentica de populaes de pequenos mamferos no Brasil central. Em suma, os resultados apresentados corroboram a proposio de que a diversidade Neotropical no poder ser explicada atravs de um nico modelo de especiao e que estes no so mutuamente exclusivos. O entendimento integral dos processos ecolgicos e histricos que deram origem fauna Neotropical, assim como a continuidade de estudos sistemticos, depende da realizao de novas amostragens e consequente enriquecimento dos museus com coleces apropriadas.
Resumo:
Na evoluo bacteriana, a capacidade de explorar novos ambientes e de responder a diferentes presses selectivas deve-se principalmente aquisio de novos genes por transferncia horizontal. Integres so elementos genticos bacterianos que constituem sistemas naturais de captura e expresso de cassetes de genes, sendo um dos principais mecanismos bacterianos envolvidos na aquisio de resistncias a antibiticos. Estudos recentes suportam a hiptese de que os ambientes naturais constituem importantes reservatrios de integres e cassetes de genes. Uma vez que as guas residuais so descarregadas em receptores naturais, torna-se fundamental conhecer a presena e disperso de integres nestes ambientes, assim como a sua associao a outros elementos genticos mveis e a genes de resistncias a antibiticos. Neste trabalho, pretendeu-se avaliar a prevalncia e diversidade de integres em guas residuais de origem animal e domstica, bem como a sua associao a plasmdeos conjugativos, usando metodologias dependentes e independentes do cultivo de microrganismos em laboratório. Os resultados obtidos sustentam assim a hiptese de que ambientes particularmente ricos em matria orgnica, como o caso das guas residuais, constituem ambientes propcios presena de integres e ocorrncia de transferncia horizontal de genes de resistncia a antibiticos, embora a sua prevalncia e diversidade seja influenciada pelo tipo de efluente em questo. A presena de integres em estaes de tratamento de guas residuais, e em especial nos efluentes tratados, constitui assim um factor preocupante, uma vez que tal contribui para a sua disseminao e disperso por outros ecossistemas aquticos, nomeadamente rios e mares. Os mtodos utilizados permitiram tambm detectar uma elevada diversidade de cassetes de genes associadas a integres, sendo possvel que algumas dessas sequncias codifiquem para protenas que desempenhem um importante papel na adaptao bacteriana s intensas presses selectivas caractersticas deste tipo de ambientes. Assim, possvel concluir que as comunidades bacterianas presentes em guas residuais renem diferentes tipos de elementos geneticamente mveis que desempenham um importante papel no s na adaptao bacteriana, mas tambm na disseminao de determinantes genticos de resistncia para ambientes naturais. Adicionalmente, a presena de potenciais protenas com possveis aplicaes biotecnolgicas refora a importncia das guas residuais como fontes de diversidade funcional. Este trabalho incluiu tambm a criao e implementao da base de dados INTEGRALL, desenvolvida com o intuito de congregar informao acerca de integres e de uniformizar a nomenclatura de cassetes de genes.
Resumo:
Both skeletal and cardiac muscles daily burn tremendous amounts of ATP to meet the energy requirements for contraction. So, it is not surprising that the maintenance of mitochondrial morphology, number, distribution and functionality in striated muscle are important for muscle homeostasis. In these tissues mitochondria present the added dimension of two populations, the intermyofibrillar (IMF) and the subsarcolemmal (SS) mitochondria, being IMF the most abundant one. In the present thesis, the molecular mechanisms harboured in mitochondria of striated muscles were studied using animal models, to better comprehend the role of mitochondrial plasticity in several pathophysiological conditions such as aging, diabetes mellitus and bladder cancer. The comparative analysis of IMF and SS populations isolated from heart evidenced a higher respiratory chain activity of mitochondria interspersed in the contractile apparatus. The higher susceptible of SS respiratory chain complexes subunits to carbonylation, but not to nitration, seems to justify the lower respiratory chain activity observed in this mitochondrial population. Our results showed that in heart from aged mice there is an accumulation of dysfunctional mitochondria. The age-related decrease of oxidative phosphorylation activity seems to be justified, at least partially, by the increased proneness of mitochondrial proteins as OXPHOS subunits and MnSOD to oxidative modifications. Moreover, a sedentary lifestyle seems to worsen the functional consequences of aging in heart by increasing mitochondrial proteins susceptibility to nitration. In skeletal muscle from rats with type 1 diabetes mellitus induced by streptozotocin administration, we verified the accumulation of dysfunctional mitochondria due, at least in part, to the impairment of PQC system. Indeed, the decreased activity of AAA proteases was accompanied by the accumulation of oxidatively modified mitochondrial proteins with impact in respiratory chain activity. The diminishing of mitochondria activity also underlies cancer-induced muscle wasting. Indeed, using a rat model of chemically induced urothelial carcinoma we verified that the loss of gastrocnemius mass was related to mitochondrial dysfunction due to, at least partially, the down-regulation of PQC system involving the mitochondrial proteases paraplegin and Lon. PQC impairment resulted in the accumulation of oxidatively modified mitochondrial proteins. In overall, regardless the pathophysiological stimuli that promote mitochondrial alterations, there are similarities in the pattern of disease-related mitochondrial plasticity. The diminished capacity for ATP production in striated muscle seems to be due to increased oxidative damage of mitochondrial proteins, namely subunits of respiratory chain complexes, metabolic proteins and MnSOD. Our data highlighted, for the first time, the impact of mitochondrial PQC system impairment in the accumulation of oxidized proteins, exacerbating the dysfunction of this organelle in striated muscle in several pathophysiological conditions.
Resumo:
Vitis vinifera L., the most widely cultivated fruit crop in the world, was the starting point for the development of this PhD thesis. This subject was exploited following on two actual trends: i) the development of rapid, simple, and high sensitive methodologies with minimal sample handling; and ii) the valuation of natural products as a source of compounds with potential health benefits. The target group of compounds under study were the volatile terpenoids (mono and sesquiterpenoids) and C13 norisoprenoids, since they may present biological impact, either from the sensorial point of view, as regards to the wine aroma, or by the beneficial properties for the human health. Two novel methodologies for quantification of C13 norisoprenoids in wines were developed. The first methodology, a rapid method, was based on the headspace solid-phase microextraction combined with gas chromatography-quadrupole mass spectrometry operating at selected ion monitoring mode (HS-SPME/GC-qMS-SIM), using GC conditions that allowed obtaining a C13 norisoprenoid volatile signature. It does not require any pre-treatment of the sample, and the C13 norisoprenoid composition of the wine was evaluated based on the chromatographic profile and specific m/z fragments, without complete chromatographic separation of its components. The second methodology, used as reference method, was based on the HS-SPME/GC-qMS-SIM, allowing the GC conditions for an adequate chromatographic resolution of wine components. For quantification purposes, external calibration curves were constructed with -ionone, with regression coefficient (r2) of 0.9968 (RSD 12.51 %) and 0.9940 (RSD of 1.08 %) for the rapid method and for the reference method, respectively. Low detection limits (1.57 and 1.10 g L-1) were observed. These methodologies were applied to seventeen white and red table wines. Two vitispirane isomers (158-1529 L-1) and 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) (6.42-39.45 g L-1) were quantified. The data obtained for vitispirane isomers and TDN using the two methods were highly correlated (r2 of 0.9756 and 0.9630, respectively). A rapid methodology for the establishment of the varietal volatile profile of Vitis vinifera L. cv. 'Ferno-Pires' (FP) white wines by headspace solid-phase microextraction combined with comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (HS-SPME/GCxGC-TOFMS) was developed. Monovarietal wines from different harvests, Appellations, and producers were analysed. The study was focused on the volatiles that seem to be significant to the varietal character, such as mono and sesquiterpenic compounds, and C13 norisoprenoids. Two-dimensional chromatographic spaces containing the varietal compounds using the m/z fragments 93, 121, 161, 175 and 204 were established as follows: 1tR = 255-575 s, 2tR = 0,424-1,840 s, for monoterpenoids, 1tR = 555-685 s, 2tR = 0,528-0,856 s, for C13 norisoprenoids, and 1tR = 695-950 s, 2tR = 0,520-0,960 s, for sesquiterpenic compounds. For the three chemical groups under study, from a total of 170 compounds, 45 were determined in all wines, allowing defining the "varietal volatile profile" of FP wine. Among these compounds, 15 were detected for the first time in FP wines. This study proposes a HS-SPME/GCxGC-TOFMS based methodology combined with classification-reference sample to be used for rapid assessment of varietal volatile profile of wines. This approach is very useful to eliminate the majority of the non-terpenic and non-C13 norisoprenic compounds, allowing the definition of a two-dimensional chromatographic space containing these compounds, simplifying the data compared to the original data, and reducing the time of analysis. The presence of sesquiterpenic compounds in Vitis vinifera L. related products, to which are assigned several biological properties, prompted us to investigate the antioxidant, antiproliferative and hepatoprotective activities of some sesquiterpenic compounds. Firstly, the antiradical capacity of trans,trans-farnesol, cis-nerolidol, -humulene and guaiazulene was evaluated using chemical (DPPH and hydroxyl radicals) and biological (Caco-2 cells) models. Guaiazulene (IC50= 0.73 mM) was the sesquiterpene with higher scavenger capacity against DPPH, while trans,trans-farnesol (IC50= 1.81 mM) and cis-nerolidol (IC50= 1.48 mM) were more active towards hydroxyl radicals. All compounds, with the exception of -humulene, at non-cytotoxic levels ( 1 mM), were able to protect Caco-2 cells from oxidative stress induced by tert-butyl hydroperoxide. The activity of the compounds under study was also evaluated as antiproliferative agents. Guaiazulene and cis-nerolidol were able to more effectively arrest the cell cycle in the S-phase than trans,trans-farnesol and -humulene, being the last almost inactive. The relative hepatoprotection effect of fifteen sesquiterpenic compounds, presenting different chemical structures and commonly found in plants and plant-derived foods and beverages, was assessed. Endogenous lipid peroxidation and induced lipid peroxidation with tert-butyl hydroperoxide were evaluated in liver homogenates from Wistar rats. With the exception of -humulene, all the sesquiterpenic compounds under study (1 mM) were effective in reducing the malonaldehyde levels in both endogenous and induced lipid peroxidation up to 35% and 70%, respectively. The developed 3D-QSAR models, relating the hepatoprotection activity with molecular properties, showed good fit (R2LOO > 0.819) with good prediction power (Q2 > 0.950 and SDEP < 2%) for both models. A network of effects associated with structural and chemical features of sesquiterpenic compounds such as shape, branching, symmetry, and presence of electronegative fragments, can modulate the hepatoprotective activity observed for these compounds. In conclusion, this study allowed the development of rapid and in-depth methods for the assessment of varietal volatile compounds that might have a positive impact on sensorial and health attributes related to Vitis vinifera L. These approaches can be extended to the analysis of other related food matrices, including grapes and musts, among others. In addition, the results of in vitro assays open a perspective for the promising use of the sesquiterpenic compounds, with similar chemical structures such as those studied in the present work, as antioxidants, hepatoprotective and antiproliferative agents, which meets the current challenges related to diseases of modern civilization.
Resumo:
The development of mining activities over thousands of years in the region of Aljustrel is nowadays visible as a vast area of ore tailings, slag and host rocks of sulphides mineralization. The generation of acidic waters by the alteration of pyritic minerals - Acid Mine Drainage (AMD) - causes a significant impact on the river system both in the south of the village (Rib . gua Forte) and in the north of it (Rib . gua Azeda and Barranco do Farrobo), which is reflected in extremely low pH values (< 3) and high concentrations of As, Cd, Cu, Fe, Mn, Pb, Zn and sulphates. This study aimed to assess the environmental impacts extent, integrating geochemical (surface waters and stream sediments) and biological (diatoms) parameters. Three groups of sites were defined, based on sediments and water analysis, which integration with diatom data showed the same association of groups: Group 1- impacted, with acidic pH (1.9-5.1), high metal contents (0.4-1975 mg L-1) and Fe-Mg-sulphate waters, being metals more bioavailable in waters in cationic form (Me2+); mineralogically the sediments were characterized by phyllosilicates and sulphates/oxy-hydroxysulphate phases, easily solubilized, retaining a high amount of metals when precipitated; dominant taxon was Pinnularia aljustrelica (a new species); Group 2- slightly impacted, weak acid to neutral pH (5.0-6.8), metal contents not so high (0.2-25 mg L-1) and Fe-Mg-sulphate to Mg-chloride waters; dominant taxa were Brachysira neglectissima and Achnanthidium minutissimum; Group 3- unimpacted, alkaline pH (7.0-8.4), low metal contents (0-7 mg L-1) with Mg-chloride waters. In this group, metals were associated to the primary phases (e.g. sulphides), not so easily available; the existence of high chloride contents explained the presence of typical taxa of brackish/marine (e.g. Entomoneis paludosa) waters. Taxonomical aspects of the diatoms were studied (discovery of a new species: Pinnularia aljustrelica Luis, Almeida et Ector sp. nov.), as well as morphometric (size decrease of diatoms valves, as well as the appearance of deformed valves of Eunotia exigua in Group 1 and A. minutissimum in Group 2) and physiological (effective to assess the effects of metals/acidity in the photosynthetic efficiency through PAM Fluorometry) aspects. A study was carried out in an artificial river system (microcosm) that aimed to mimic Aljustrels extreme conditions in controlled laboratory conditions. The chronic effects of Fe, SO42- and acidity in field biofilms, inoculated in the artificial rivers, were evaluated as well as their contribution to the communities tolerance to metal toxicity, through acute tests with two metals (Cu and Zn). In general, the effects caused by low pH values and high concentrations of Fe and SO42- were reflected at the community level by the decrease in diversity, the predominance of acidophilic species, the decrease in photosynthetic efficiency and the increase of enzymatic (e.g. catalase, superoxide dismutase) and non-enzymatic activities (e.g. total glutathione and total phytochelatins). However, it was possible to verify that acidity performed a protective effect in the communities, upon Cu and Zn addition. A comparative study between Aljustrel mining area and New Brunswick mining area was carried out, both with similar mining and geological conditions, reflected in similar diatom communities in both mines, but in very different geographic and climatic areas.
