Brazilian savanna forest : conservation, medicinal reservoir and bioprospecting

This study aimed to analyse the Brazilian savanna forest from a Legal Reserve (LR) area from a perspective of conservation, reservoir of organic carbon and medicinal biomass for a prospective use of native medicinal plants. An ethnobotanical and ethnopharmacological survey was carried out close to a community settled in the rural area in the south of Tocantins, being selected 9 of the most cited species (caju��- Anacardium othonianum; inhar��-Brosimum gaudichaudii; jatob��-Hymenaeae courbaril; jenipapo-Genipa americana, aroeira-Myracrodruon urundeuva; negramina-Siparuna guianensis; barbatim��o- Stryphnodendron obovatum; assa peixe-Vernonia brasiliana, emba��ba-Cecropia pachystachya). Crude foliar extracts were subjected to a preliminary phytochemical prospection and triage of secondary metabolites with antimicrobial activity of potential interest in health and familiar agriculture. Phenolic compounds, terpenes and flavonoids were detected in the extracts of most species, which suggests the presence of antimicrobial, antioxidant and anti-insect activities. It was evident the need to better know the LR as a reservoir of medicinal biomass in an area under ecological tension where 35% (610ha) of the property is LR and should be protected by law. Therefore, a forest inventory of live woody species was performed using the allometric or indirect method. This identified a rare remnant of Semidecidual Seasonal Forest amidst the largest world savannah, the Cerrado biome. An analysis of the forest average productivity per basal area (m��.ha), aerial live biomass (ton.ha-1) and carbon stock was carried out. The forest fragment was considered relatively rich in species and diversity, although showing signs of disturbance and dominance by a few species. Its horizontal structure suggests biotic regeneration conditions. It is an important reservoir of medicinal plants. Of the families (57.5%) presenting medicinal species, 19 from a total of 33 are represented in the area and contain 44% (27) of the total species (61) and 63% (432) of the total individuals catalogued. Medicinal species have ecological importance for the equilibrium of the local flora and represent 80% of the 10 species with higher Importance Value Index (IVI): Tetragastris altissima, Chrysophyllum marginatum, Oenocarpus distichus, Sclerolobium paniculatum, Simarouba versicolor, Alibertia macrophylla, Siparuna guianensis, Maprounea guianensis, Licania parvifolia e Physocalymma scaberrimum. Medicinal productivity was high for this type of phytophysionomy: 183,2 ton. ha-1 of biomass and 91,51 ton. ha-1 of carbon representing 66% of the total biomass and carbon of this Cerrado forest. From this stage S. guianensis (Siparunaceae) was selected for performing bioassays in order to verify its biological activity against microorganisms of health and agricultural relevance. This is a native aromatic medicinal plant recommended as priority for conservation, with local popular medicinal validation and availability of medicinal feedstock (3300 Kg.ha-1), with the foliar fraction giving 38Kg/ha of crude extract and 5L/ha of essential oil. Foliar crude extracts and essential oil were obtained and tested in vitro using a disk diffusion bioassay. Different concentrations of these natural products were tested against gram-positive bacteria (Staphylococcus aureus ATCC 29213), gram-negative bacteria (Escherichia coli ATCC 25922 and ATCC 35218; Pseudomonas aeruginosa ATCC 10145) and fungi (Candida albicans ATCC 6258 e Fusarium oxysporum). The essential oil inhibited the growth of S. aureus in its crude concentration (380��g.mL-1), as well as diluted to half (190��g.mL-1) and a quarter strength (95��g.mL-1). It���s likely that such action is due to sesquiterpenes major components, such as bisabolol and bisabolene (10.35%), measured by gas chromatography (GC-MS, GC-FID). Extracts did not exhibit any antimicrobial activity against the microorganisms tested. The native medicinal plants prospective market is an alternative that favours the conservation of biodiversity while generating benefits for the development of sustainable family productive activities within local ecosystems instead of the current inappropriate uses. This strengthens conservation policies of Legal Reserve in rural settlements and is in agreement with public policy on global warming and climate changes.

Derivation of soil screening values for metals in Portuguese natural soil

The increasing human activity has been responsible by profound changes and a constinuos degradation of the soil compartment in all the European territory. Some European policies are appearing focusing soil���s protection and the management of contaminated sites, in order to recover land for other uses. To regulate the risk assessment and the management of contaminated soils, many European member states adopted soil guideline values, as for example soil screnning values (SSV).These values are particularly useful for the the first tier of the Ecological Risk Assessment (ERA) processes of contaminated sites,especially for a first screening of sites requiring a more site-specific evaluation. Hence, the approriate definition of regional SSVs will have relevant economic impacts in the management of contaminated sites. Portugal is one of European Member States that still lack these soil guideline values. In this context, this study gaves a remarkable contribution in the generation of ecotoxicological data for soil microbiological parameters, terrestrial plants and invertebrates for the derivation of SSVs for uranium (U), cadmium (Cd) and copper (Cu), using a Portuguese natural soil, representative of a dominant type of soil in the Portuguese territory. SSVs were derived based on two methods proposed by the the Technical Guidance Document for Risk Assessment of the European Commission; namely the assessment factor method (AF) and the species sensitivity distribution (SSD) method (with some adaptations). The outputs of both methods were compared and discussed. Further, this study laid the foundation for a deeper reflection about the cut-off (hazard concentration for a given percentage of species - HCps) to be estimated from the SSDs, and to be selected for the derivation of SSVs, with the adequate level of protection. It was proven that this selection may vary for different contaminants, however a clear justification should be given, in each case. The SSvs proposed in this study were for: U (151.4 mg U kg-1dw), Cd (5.6 mg Cd kg-1dw), and Cu (58.5 mg Cu kg-1dw) These values should now be tested for their descriminating power of soils with different levels of contamination. However, this studies clarifies the approach that should be followed for the derivation of SSVs for other metals and organic contaminants, and for other dominant types of Portuguese natural soils.

Explora����o matem��tica de m��dulos interativos de ci��ncias: um estudo de caso no "Jardim da Ci��ncia" em articula����o com a sala de aula com alunos do 1�� ciclo do ensino b��sico

Orienta����es curriculares portuguesas para o 1.�� Ciclo do Ensino B��sico [CEB] preconizam o desenvolvimento de capacidades transversais como a resolu����o de problemas [RP] e a comunica����o (em) matem��tica [CM], o estabelecimento de conex��es Matem��tica���Ci��ncias F��sicas e Naturais [CFN] e a articula����o de contextos de educa����o formal [EF] e de educa����o n��o formal [ENF]. Em Portugal, professores manifestam querer utilizar recursos did��ticos com estes atributos. Contudo, tais recursos escasseiam, assim como investiga����o que se situa na conflu��ncia destas dimens��es. Por conseguinte, na presente investiga����o, foram desenvolvidos recursos did��ticos centrados na promo����o de conex��es Matem��tica-Ci��ncias F��sicas e Naturais e na articula����o de contextos de EF e de ENF. Assim, a presente investiga����o tem por finalidade desenvolver (conceber, produzir, implementar e avaliar) recursos did��ticos de explora����o matem��tica de m��dulos interativos de ci��ncias, articulando contextos de EF e ENF que, nomeadamente, apelem e possam desenvolver capacidades b��sicas ligadas �� RP e �� CM de alunos do 1.�� CEB. Decorrente desta finalidade, definiram-se as seguintes quest��es de investiga����o: 1. Quais as repercuss��es dos recursos did��ticos desenvolvidos na capacidade de RP de alunos do 4.�� ano do 1.�� CEB?; 2. Quais as repercuss��es dos recursos did��ticos desenvolvidos na capacidade de CM de alunos do 4.�� ano do 1.�� CEB?. Al��m disso, procurou-se auscultar a opini��o de alunos e professora sobre a explora����o dos recursos did��ticos desenvolvidos, principalmente, ao n��vel de conex��es Matem��tica���CFN e articula����o de contextos de EF e ENF de Ci��ncias. Para tanto, foi realizado um estudo de caso com uma professora e seus alunos do 4.�� ano do 1.�� CEB, em sala de aula e num espa��o de ENF de Ci��ncias. A recolha de dados envolveu diversas t��cnicas e v��rios instrumentos. A t��cnica de an��lise documental incidiu nas produ����es dos alunos registadas em Gui��es do Aluno e em Tarefas-Teste. No ��mbito da t��cnica de inquiri����o foram administrados question��rios a todos os alunos da turma ��� o Question��rio Inicial e o Question��rio Final ��� e entrevistas semiestruturadas �� professora ��� a Entrevista Inicial �� Professora e a Entrevista Final �� Professora ��� e aos tr��s alunos caso ��� Entrevista ao aluno caso. No que respeita �� t��cnica de observa����o foi implementado o instrumento Notas de campo, onde foram efetuados registos de natureza descritiva e reflexiva. Os dados recolhidos foram objeto de an��lise de conte��do e de an��lise estat��stica. Resultados da investiga����o apontam para que a explora����o dos recursos did��ticos desenvolvidos possa ter promovido o desenvolvimento de capacidades matem��ticas de RP e, sobretudo, de CM dos alunos. Parecem ainda indicar que, genericamente, os alunos e a professora possam ter considerado que os recursos did��ticos promoveram conex��es Matem��tica��� CFN e a articula����o entre espa��os de EF e ENF de Ci��ncias.

Sustainable viticulture in Bairrada appellation: vineyard and harvest year effects on grapes oenological potential

The sustainable viticulture of a region passes, among other aspects, for maximizing the varieties potential minimizing subsequent interventions during winemaking, which should contribute to the production of quality wines maintaining their typicity and rationalizing costs. The detailed knowledge of each Appellation specificities, namely vineyard parcel (soil type and topographical peculiarities) and harvest climatic conditions is crucial for sustainability in this sector. Thus, in line with this current trend, the starting point for the development of this PhD thesis was to evaluate the oenological potential of different varieties cultivated throughout Bairrada Appellation (Portugal). During maturation several changes in grape varieties occur, namely berries become sweeter, less acidic, and they develop flavour, aroma and colour properties. The development of these characteristics is essential to define grapes oenological potential, i.e. to estimate the possibility of their usage to produce specific wines. A three years sampling plan was designed to evaluate the effect of harvest year and parcel characteristics on V. vinifera cv. Arinto, Bical, Sauvignon Blanc, Baga, Castel��o, Touriga Nacional, and Sous��o grapes composition. For each variety, 3 parcels with different characteristics were selected. Several physicochemical parameters were evaluated, during maturation: berry weight, pH, titratable acidity, sugar and phenolic contents, antiradical activity, and volatile composition (free fraction). Special attention was devoted to grapes at technologic maturity, since, besides these parameters, glycosidically-linked fraction was also considered. By using the results obtained at technologic maturity, a comprehensive approach was applied to identify the significance of harvest and parcel characteristics effects on each variety composition. Considering all the parameters under study, it may be highlighted some significant differences. According to the obtained results determined during maturation, it was possible to conclude that Arinto, Bical and Sauvignon Blanc grapes from parcels with clay-sandy and clay-calcareous soils have higher phenolic content and antiradical activity. Otherwise, Sauvignon Blanc presented similar volatile composition for grapes cultivated in the 3 parcels, while Arinto and Bical exhibited higher volatile content in grapes from claysandy and clay-calcareous soils. For Baga, Castel��o and Touriga Nacional red varieties, grapes with higher phenolic content, antiradical activity, and volatile content were obtained from clayey and clay-calcareous soils. Furthermore, for Touriga Nacional, parcels altitude seems also to modulate grapes composition. Beyond parcel effect, harvest year conditions also influence grapes composition: 2011 harvest was related with lower phenolic and volatile contents, as well as lower antiradical activity.For grapes collected at technologic maturity, analysis of variance-simultaneous component analysis (ASCA) was applied combining all the parameters under study, in order to assess the influence of harvest and parcel characteristics on each variety oenological potential. The results obtained using this comprehensive approach is closely related with those observed during maturation and revealed that harvest was the main factor that influenced grapes composition (53% to 68% of the total data set variance) followed by parcel characteristics, explaining ca. 15-19% of the total data set variance. The oenological potential of each variety may be different from one parcel to another, i.e., clay-sandy and clay-calcareous related-environments seem to favour Arinto and Bical white grapes composition, but for the red varieties, grapes composition was favoured by clayey and clay-calcareous soils. Besides, also higher altitude seems to favour Touriga Nacional grapes composition. Sauvignon Blanc seems to be a variety well adapted to the different parcel characteristics. In order to go forward in the valuation of these varieties, the aroma properties of 6 monovarietal wines were studied based on an aroma network-approach, linking molecular data related to volatile composition and aroma data about the key odor active molecules. This approach allowed to identify different wine aroma properties and to infer about the consumer���s sensory perception. It was found that aroma properties differ from one wine variety to another: while Arinto and Sauvignon Blanc wine exhibited higher tree fruity, sweety and flowery aromas, related essentially with ester compounds and C13 norisoprenoids, the opposite was obtained for Bical wine, corroborating the aroma sensory perceptions of the trained panel. Sauvignon Blanc also exhibited higher toasted aromas (related with thiols, mainly with 2-methyl-3-furanthiol). Touriga Nacional red wine exhibited higher tree, tropical, and berry fruits notes (sensory described as sweet fruits), toasted and flowery aromas, while these are similar for the other red wines under study. Besides Portuguese Bairrada wines, this aroma network approach is a tool that can be used to explain the aroma properties of wines worldwide. The grape and wine data generated under the present PhD thesis, in the context of Bairrada Appellation, shows the unique character of each variety, and may be used by growers and wine producers as a support for decisionmaking based on objective criteria, increasing the sustainability in this sector. For instance, it is possible to take advantage of the natural resources and produce products with different characteristics obtained from the same variety, minimizing costs during the winemaking process.

Single and joint effects of natural and chemical stressors to the terrestrial isopod Porcellionides pruinosus

Environmental contamination and climate changes constitute two of the most serious problems affecting soil ecosystems in agricultural fields. Agriculture is nowadays a highly optimized process that strongly relies on the application of multiple pesticides to reduce losses and increase yield production. Although constituting, per se, a serious problem to soil biota, pesticide mixtures can assume an even higher relevance in a context of unfavourable environmental conditions. Surprisingly, frameworks currently established for environmental risk assessments keep not considering environmental stressors, such as temperature, soil moisture or UV radiation, as factors liable to influence the susceptibility of organisms to pesticides, or pesticide mixtures, which is raising increasing apprehension regarding their adequacy to actually estimate the risks posed by these compounds to the environment. Albeit the higher attention received on the last few years, the influence of environmental stressors on the behaviour and toxicity of chemical mixtures remains still poorly understood. Aiming to contribute for this discussion, the main goal of the present thesis was to evaluate the single and joint effects of natural stressors and pesticides to the terrestrial isopod Porcellionides pruinosus. The first approach consisted on evaluating the effects of several abiotic factors (temperature, soil moisture and UV radiation) on the performance of P. pruinosus using several endpoints: survival, feeding parameters, locomotor activity and avoidance behaviour. Results showed that these stressors might indeed affect P. pruinosus at relevant environmental conditions, thus suggesting the relevance of their consideration in ecotoxicological assays. At next, a multiple biomarker approach was used to have a closer insight into the pathways of damage of UV radiation and a broad spectrum of processes showed to be involved (i.e. oxidative stress, neurotoxicity, energy). Furthermore, UV effects showed to vary with the environment medium and growth-stage. A similar biomarker approach was employed to assess the single and joint effects of the pesticides chlorpyrifos and mancozeb to P. pruinosus. Energy-related biomarkers showed to be the most differentiating parameters since age-classes seemed to respond differently to contamination stress and to have different metabolic costs associated. Finally, the influence of temperature and soil moisture on the toxicity of pesticide mixtures was evaluated using survival and feeding parameters as endpoints. Pesticide-induced mortality was found to be oppositely affected by temperature, either in single or mixture treatments. Whereas chlorpyrifos acute toxicity was raised under higher temperatures the toxicity of mancozeb was more prominent at lower temperatures. By the opposite, soil moisture showed no effects on the pesticide-induced mortality of isopods. Contrary to survival, both temperature and soil moisture showed to interact with pesticides to influence isopods��� feeding parameters. Nonetheless, was however the most common pattern. In brief, findings reported on this thesis demonstrated why the negligence of natural stressors, or multiple stressors in general, is not a good solution for risk assessment frameworks.

Extraction of added-value products from biomass using ionic liquids

The main purpose of this thesis is to investigate the potential of ionic liquids (ILs) as a new class of extractive solvents for added-value products from biomass. These include phenolic compounds (vanillin, gallic, syringic and vanillic acids), alkaloids (caffeine) and aminoacids (L-tryptophan). The interest on these natural compounds relies on the wide variety of relevant properties shown by those families and further application in the food, cosmetic and pharmaceutical industries. Aiming at developping more benign and effective extraction/purification techniques than those used, a comprehensive study was conducted using aqueous biphasic systems (ABS) composed of ILs and inorganic/organic salts. In addition, ILs were characterized by a polarity scale, using solvatochromic probes, aiming at providing prior indications on the ILs affinity for particular added-value products. Solid-liquid (S-L) extractions from biomass and using aqueous solution of ILs were also investigated. In particular, and applying and experimental factorial design to optimize the operational conditions, caffeine was extracted from guaran�� seeds and spent coffee. With both types of extractions it was found that it is possible to recover the high-value compounds and to recycle the IL and salt solutions. Finally, aiming at exploring the recovery of added-value compounds from biomass using a simpler and more suistainable technique, the solubility of gallic acid, vanillin and caffeine was studied in aqueous solutions of several ILs and common salts. With the gathered results it was possible to demonstrate that ILs act as hydrotropes and that water can be used as an adequate antisolvent. This thesis describes the use of ILs towards the development of more effective and sustainable processes.

Barrier properties of poly(lactic acid) based films

In recent years, the search for a environmentally friendly products has increased. One of the major challenges has been the demand for biodegradable materials that can replace plastic. If a few decades ago, plastic replaced, for example, the ivory in billiard balls, and in other products, saving the lives of thousands elephants, nowadays a replacement for that plastic is being searched, to prevent the change of the environmental conditions, essential to life in harmonly with the fauna and flora that the human specie has, in recent years, destroyed. Plastic is a petroleum derivate, whose price has been growing exponentially, mainly due to the fact of beind a cheap material and also to enable the production of products that are essential to modern life. Therefore, the petrochemical era is going to come to an end and a new environmentally sustainable era, based on biodegradable materials from renewable sources, will follow. The change to green routes only will be possible with the support of the major companies, and the implementation of drastic governmental law. Poly(lactic acid), PLA, is produced from the lactose present in the corn or sugarcane and has been intensively studied in recent years because if some limitants properties required its extrusion are overcome, it has the potential to replace the traditional polymers. PLA have high brittleness, low toughness and low tensile elongation. In this work, natural antioxidant (alpha-tocopherol) and synthetics antioxidants (BHT ant TBHQ) were added to the PLA with the aim not only to improve their flexibility, but also to create an active packaging to extend the shelf life of the foods and improve the organoleptic properties by preventing food losses. The impact of the addition of antioxidants into the PLA films, in its mechanical, thermal and barrier properties were studied by FTIR, DSC, SEM, AFM, DMA, TGA, QCM and time-lag techniques.

4-Quinolonas: novos m��todos de s��ntese e transforma����o em acridonas

A presente disserta����o �� constitu��da por quatro cap��tulos, organizados em introdu����o geral, discuss��o do trabalho desenvolvido na s��ntese de quinolin-4(1H)-onas e acridonas, caracteriza����o estrutural dos novos compostos sintetizados e parte experimental. No primeiro cap��tulo desta disserta����o �� apresentada uma breve revis��o bibliogr��fica de quinolin-4(1H)-onas e acridonas, abrangendo a respectiva nomenclatura, ocorr��ncia natural e m��todos de s��ntese. O segundo cap��tulo engloba estudos da reactividade de (E)-2-estirilquinolin-4(1H)-onas e (E)-N-(2-acetilfenil)-3-arilacrilamidas como dien��filos com o-benzoquinodimetanos, gerados in situ a partir da extrus��o quelotr��pica do di��xido de enxofre de 2,2-di��xidos de 1,3-di-hidrobenzo[c]tiofenos. Estes estudos conduziram �� obten����o de novas 2-(3-aril-1,2,3,4-tetra-hidronaftalen-2-il)-1-metilquinolin-4(1H)-onas e an��logos n��o substitu��dos no ��tomo de azoto N1 da quinolin-4(1H)-ona. Em seguida foram estudadas as rea����es de desidrogena����o e fotocicliza����o dos compostos obtidos anteriormente, com vista �� obten����o de novas 2-(3-arilnaftalen-2-il)-1-metilquinolin-4(1H)-onas, an��logos n��o substitu��dos em N1 e de novas acridonas. No segundo cap��tulo tamb��m �� abordada a s��ntese dos compostos precursores, as (E)-N-(2-acetilfenil)-3-arilacrilamidas, as (E)-2-estirilquinolin-4(1H)-onas e os 2,2-di��xidos de 1,3-di-hidrobenzo[c]tiofenos. No terceiro capitulo �� discutida a caracteriza����o estrutural das novas quinolin-4(1H)-onas e acridona sintetizadas, com estudos de espetroscopia de resson��ncia magn��tica nuclear 1D (1H e 13C) e 2D (homo- e heteronuclear). O quarto cap��tulo inclui toda a parte experimental, contendo os procedimentos optimizados para a s��ntese e purifica����o destes compostos, e a caracteriza����o estrutural dos novos compostos sintetizados.

Avan��os metodol��gicos na s��ntese de novos derivados de flavonas

As estirilflavonas poli-hidroxiladas s��o compostos heteroc��clicos de natureza polifen��lica que suscitam interesse devido �� atividade biol��gica que possuem atuando, por exemplo, como antioxidantes. O desenvolvimento de novas rotas de s��ntese de estirilflavonas constitui um desafio e �� neste contexto que se t��m efetuado v��rios estudos sobre a aplica����o de rea����es de acoplamento cruzado catalisadas por pal��dio, como a rea����o de Heck, na prepara����o deste tipo de compostos. Nesta disserta����o reporta-se a s��ntese de (E)-8-estirilflavonas atrav��s da rea����o de Heck de 8-iodoflavonas com derivados de estireno com rendimentos excelentes, descrevendo-se um estudo no qual se optimizaram as condi����es experimentais desta rea����o. Adicionalmente, descrevem-se duas tentativas de desmetila����o da (E)-8-[2-(4-metoxifenil)vinil]-4���,5,7-trimetoxiflavona. As 8- iodoflavonas foram preparadas com elevada regiosseletividade atrav��s da cicliza����o oxidativa/ioda����o das (E)-2���-hidroxicalconas correspondentes por aplica����o do sistema de reagentes I2/DMSO. A prop��sito, descreve-se um estudo de cicliza����o oxidativa/ioda����o da (E)-2���-hidroxi-4,4���,6���- trimetoxicalcona, no qual se testou a aplica����o do sistema de reagentes I2/DMSO na s��ntese de iodoflavonas em rea����es one-pot. As (E)-2���- hidroxicalconas foram sintetizadas atrav��s da condensa����o ald��lica catalisada por base entre a 2���-hidroxi-4���,6���-dimetoxiacetofenona, previamente preparada, e derivados de benzalde��do. A carateriza����o estrutural da maioria dos compostos obtidos neste trabalho foi efetuada com base em estudos de espetroscopia de resson��ncia magn��tica nuclear (RMN), nomeadamente de 1H e 13C, e, sempre que poss��vel, em estudos bidimensionais de correla����o espetrosc��pica heteronuclear (HSQC e HMBC), bem como em estudos de espetrometria de massa (EM).

O questionamento como elemento integrador do blogue nas aulas de ci��ncias

A investiga����o sobre a promo����o do questionamento na rela����o pedag��gica revela ser uma estrat��gia que valoriza o papel do aluno enquanto aquele que aprende, alterando a forma como as aulas s��o vividas por alunos e professores. Perante a inexist��ncia de estudos que ensaiem o est��mulo ao questionamento e, simultaneamente, integrem a Web 2.0 no processo de ensino e de aprendizagem no Ensino B��sico, delineou-se a presente investiga����o. O estudo situa-se, assim, na interse����o de dois campos: por um lado, as potencialidades do incentivo ao questionamento no processo pedag��gico e, por outro, a integra����o educativa das TIC. A quest��o de Investiga����o que orientou este estudo foi a de avaliar de que forma �� que o incentivo ao questionamento poderia contribuir para integrar o blogue de disciplina no trabalho em sala de aula de Ci��ncias Naturais. Assim, concebemos, implement��mos e avali��mos uma interven����o did��tica centrada na promo����o da compet��ncia de questionamento, dando voz aos alunos, estimulando-os a formularem perguntas sobre os conte��dos, tanto presencialmente como no blogue da disciplina, denominado por ���Mentes Curiosas���, utilizando essas perguntas como elementos integradores dos dois espa��os. O estudo seguiu uma metodologia de investiga����o-a����o e envolveu 36 alunos do 9.�� ano de escolaridade, divididos em duas turmas, na disciplina de Ci��ncias Naturais. Os instrumentos e m��todos de recolha de dados foram diversificados, tendo todos os dados sido submetidos a uma an��lise de conte��do. O estudo revela que os alunos utilizaram o blogue respondendo aos desafios colocados escrevendo coment��rios, respostas e, sobretudo, fazendo perguntas para as quais gostariam de obter respostas. O docente integrou essas perguntas na pr��tica letiva dando continuidade ��s discuss��es de um ambiente para o outro, utilizando, desta forma, as perguntas dos alunos para a integra����o dos dois ambientes. A an��lise do questionamento registado revela que as perguntas online est��o mais centradas nos conte��dos cient��ficos e apresentam maior qualidade cognitiva quando comparadas com as formuladas em sala de aula. Por sua vez, no contexto presencial, as perguntas escritas s��o de maior n��vel de complexidade do que as perguntas orais. Atrav��s das diversas estrat��gias implementadas, quer para a promo����o da capacidade de escrever perguntas, quer no trabalho realizado com o blogue, transformou-se a din��mica do trabalho em sala de aula, melhorando-se o empenhamento dos alunos na aprendizagem. A estrat��gia de incentivo ao questionamento pelos alunos revelou-se, assim, como um fator que permite integrar de forma prof��cua o ambiente online no ambiente presencial neste n��vel de ensino. Por fim, a reflex��o que fomos fazendo sobre as potencialidades do questionamento na rela����o professor-alunos-conte��dos, tanto no ambiente presencial como no virtual, levou-nos a perspetivar as perguntas segundo duas dimens��es: Compet��ncia Cognitiva e Estrat��gia Did��tica. Enquanto Compet��ncia, o questionamento assume a fun����o de ferramenta cognitiva e de regulador do processo de ensino e de aprendizagem. Enquanto Estrat��gia, a pergunta pode ser encarada como uma ferramenta did��tica na rela����o dial��gica que se estabelece entre professor e alunos.

Combined effects of chemical and natural stressors to soil organisms and plants

Nas ��ltimas d��cadas, a Terra tem experimentado um aquecimento global e mudan��as nos padr��es de precipita����o. Muitos estudos sobre a avalia����o de risco de agrot��xicos em organismos n��o-alvo foram realizados com base em protocolos padronizados, com condi����es abi��ticas controladas. Mas, em campo, os organismos s��o expostos a flutua����es de v��rios fatores ambientais, bem como a poluentes, que podem alterar os limites de toler��ncia dos organismos aos stressores naturais, bem como alterar a toxicidade ou biodisponibilidade do qu��mico em causa. Considerando isso, o principal objetivo deste trabalho foi o de avaliar de que modo e em que medida os fatores ambientais (temperatura, humidade do solo e radia����o UV) podem interagir uns com os outros ou afetar a toxicidade do carbaril para invertebrados do solo e plantas. Para isso, foram utilizadas quatro esp��cies padr��o: Folsomia candida, Eisenia andrei, Triticum aestivum e Brassica rapa, e simulados diferentes cen��rios clim��ticos, com v��rios par��metros letais e subletais analisados. A exposi����o combinada foi analisada utilizando, quando poss��vel, a ferramenta MIXTOX, com base no modelo de refer��ncia de ac����o independente (IA) e poss��veis desvios, assim como r��cios sinerg��sticos/antagon��sticos (a partir de valores de EC50/LC50), quando a dose-resposta de um dos stressores n��o foi obtida. Todos os fatores de stress aplicados isoladamente causaram efeitos significativos sobre as esp��cies testadas e sua exposi����o combinada com carbaril, apresentaram respostas diferenciadas: para as minhocas, a seca e temperaturas elevadas aumentaram os efeitos delet��rios do carbaril (sinergismo), enquanto o alagamento e temperaturas baixas diminu��ram sua toxicidade (antagonismo). Para os col��mbolos, o modelo IA mostrou ser uma boa ferramenta para prever a toxicidade do carbaril tanto para temperaturas altas como para as baixas. Para as duas esp��cies de plantas foram encontradas diferen��as significativas entre elas: em termos gerais, as intera����es entre carbaril e os stressores naturais foram observadas, com sinergismo aparecendo como o padr��o principal relacionado com a radia����o UV, solos secos e temperaturas elevadas, enquanto o padr��o principal relacionado com temperaturas baixas e stress de alagamento foi o antagonismo. Quando os efeitos de dois stressores naturais (radia����o UV e humidade do solo) em plantas foram avaliados, uma intera����o significativa foi encontrada: a seca aliviou o efeito delet��rio da radia����o UV em T. aestivum e o alagamento aumentou os seus efeitos, mas para B. rapa a adi����o de ambos os stresses de ��gua causou um aumento (sinergismo) dos efeitos delet��rios da radia����o UV para todos os par��metros avaliados. Portanto �� necess��rio que as diferen��as sazonais e latitudinais, bem como as mudan��as clim��ticas globais, sejam integradas na avalia����o de risco de contaminantes do solo.

Resistance to last-resort antibiotics in natural environments

Last-resort antibiotics are the final line of action for treating serious infections caused by multiresistant strains. Over the years the prevalence of resistant bacteria has been increasing. Natural environments are reservoirs of antibiotic resistance, highly influenced by human-driven activities. The importance of aquatic systems on the evolution of antibiotic resistance is highlighted from the assumption that clinically-relevant resistance genes have originated in strains ubiquitous in these environments. We hypothesize that: a) rivers are reservoirs and disseminators of antibiotic resistance; b) anthropogenic activities potentiate dissemination of resistance to last-resort antibiotics. Hence, the main goal of the work is to compare the last-resort antibiotics resistome, in polluted and unpolluted water. Rivers from the Vouga basin, exposed to different anthropogenic impacts, were sampled. Water quality parameters were determined to classify rivers as unpolluted or polluted. Two bacterial collections were established enclosing bacteria resistant to cefotaxime (3rd generation cephalosporin) and to imipenem (carbapenem). Each collection was characterized regarding: phylogenetic diversity, antibiotic susceptibility, resistance mechanisms and mobile genetic elements. The prevalence of cefotaxime- and imipenem-resistant bacteria was higher in polluted water. Results suggested an important role in the dissemination of antibiotic resistance for Enterobacteriaceae, Pseudomonas and Aeromonas. The occurrence of bacteria resistant to non-beta-lactams was higher among isolates from polluted water as also the number of multiresistant strains. Among strains resistant to cefotaxime, extended-spectrum beta-lactamase (ESBL) genes were detected (predominantly blaCTX-M-like) associated to mobile genetic elements previously described in clinical strains. ESBL-producers were often multiresistant as a result of co-selection mechanisms. Culture-independent methods showed clear differences between blaCTX-M-like sequences found in unpolluted water (similar to ancestral genes) and polluted water (sequences identical to those reported in clinical settings). Carbapenem resistance was mostly related to the presence of intrinsically resistant bacteria. Yet, relevant carbapenemase genes were detected as blaOXA-48-like in Shewanella spp. (the putative origin of these genes), and blaVIM-2 in Pseudomonas spp. isolated from polluted rivers. Culture-independent methods showed an higher than the previously reported diversity of blaOXA-48-like genes in rivers. Overall, clear differences between polluted and unpolluted systems were observed, regarding prevalence, phylogenetic diversity and susceptibility profiles of resistant bacteria and occurrence of clinically relevant antibiotic resistance genes, thus validating our hypotheses. In this way, rivers act as disseminators of resistance genes, and anthropogenic activities potentiate horizontal gene transfer and promote the constitution of genetic platforms that combine several resistance determinants, leading to multiresistance phenotypes that may persist even in the absence of antibiotics.

Assessing the effectiveness of chemical treatment with nanomaterials in improving the quality of different industrial effluents

Industrial activities are the major sources of pollution in all environments. Depending on the type of industry, various levels of organic and inorganic pollutants are being continuously discharged into the environment. Although, several kinds of physical, chemical, biological or the combination of methods have been proposed and applied to minimize the impact of industrial effluents, few have proved to be totally effective in terms of removal rates of several contaminants, toxicity reduction or amelioration of physical and chemical properties. Hence, it is imperative to develop new and innovative methodologies for industrial wastewater treatment. In this context nanotechnology arises announcing the offer of new possibilities for the treatment of wastewaters mainly based on the enhanced physical and chemical proprieties of nanomaterials (NMs), which can remarkably increase their adsorption and oxidation potential. Although applications of NMs may bring benefits, their widespread use will also contribute for their introduction into the environment and concerns have been raised about the intentional use of these materials. Further, the same properties that make NMs so appealing can also be responsible for producing ecotoxicological effects. In a first stage, with the objective of selecting NMs for the treatment of organic and inorganic effluents we first assessed the potential toxicity of nanoparticles of nickel oxide (NiO) with two different sizes (100 and 10-20 nm), titanium dioxide (TiO2, < 25 nm) and iron oxide (Fe2O3, ��� 85x425 nm). The ecotoxicological assessment was performed with a battery of assays using aquatic organisms from different trophic levels. Since TiO2 and Fe2O3 were the NMs that presented lower risks to the aquatic systems, they were selected for the second stage of this work. Thus, the two NMs pre-selected were tested for the treatment of olive mill wastewater (OMW). They were used as catalyst in photodegradation systems (TiO2/UV, Fe2O3/UV, TiO2/H2O2/UV and Fe2O3/H2O2/UV). The treatments with TiO2 or Fe2O3 combined with H2O2 were the most efficient in ameliorating some chemical properties of the effluent. Regarding the toxicity to V. fischeri the highest reduction was recorded for the H2O2/UV system, without NMs. Afterwards a sequential treatment using photocatalytic oxidation with NMs and degradation with white-rot fungi was applied to OMW. This new approach increased the reduction of chemical oxygen demand, phenolic content and ecotoxicity to V. fischeri. However, no reduction in color and aromatic compounds was achieved after 21 days of biological treatment. The photodegradation systems were also applied to treat the kraft pulp mill and mining effluents. For the organic effluent the combination NMs and H2O2 had the best performances in reduction the chemical parameters as well in terms of toxicity reduction. However, for the mine effluent the best (TiO2/UV and Fe2O3/UV) were only able to significantly remove three metals (Zn, Al and Cd). Nonetheless the treatments were able of reducing the toxicity of the effluent. As a final stage, the toxicity of solid wastes formed during wastewater treatment with NMs was assessed with Chironomus riparius larvae, a representative species of the sediment compartment. Certain solid wastes showed the potential to negatively affect C. riparius survival and growth, depending on the type of effluent treated. This work also brings new insights to the use of NMs for the treatment of industrial wastewaters. Although some potential applications have been announced, many evaluations have to be performed before the upscaling of the chemical treatments with NMs.

Codon ambiguities as a mechanism to alter the genetic code in Saccharomyces cerevisiae

Although the genetic code is generally viewed as immutable, alterations to its standard form occur in the three domains of life. A remarkable alteration to the standard genetic code occurs in many fungi of the Saccharomycotina CTG clade where the Leucine CUG codon has been reassigned to Serine by a novel transfer RNA (Ser-tRNACAG). The host laboratory made a major breakthrough by reversing this atypical genetic code alteration in the human pathogen Candida albicans using a combination of tRNA engineering, gene recombination and forced evolution. These results raised the hypothesis that synthetic codon ambiguities combined with experimental evolution may release codons from their frozen state. In this thesis we tested this hypothesis using S. cerevisiae as a model system. We generated ambiguity at specific codons in a two-step approach, involving deletion of tRNA genes followed by expression of non-cognate tRNAs that are able to compensate the deleted tRNA. Driven by the notion that rare codons are more susceptible to reassignment than those that are frequently used, we used two deletion strains where there is no cognate tRNA to decode the rare CUC-Leu codon and AGG-Arg codon. We exploited the vulnerability of the latter by engineering mutant tRNAs that misincorporate Ser at these sites. These recombinant strains were evolved over time using experimental evolution. Although there was a strong negative impact on the growth rate of strains expressing mutant tRNAs at high level, such expression at low level had little effect on cell fitness. We found that not only codon ambiguity, but also destabilization of the endogenous tRNA pool has a strong negative impact in growth rate. After evolution, strains expressing the mutant tRNA at high level recovered significantly in several growth parameters, showing that these strains adapt and exhibit higher tolerance to codon ambiguity. A fluorescent reporter system allowing the monitoring of Ser misincorporation showed that serine was indeed incorporated and possibly codon reassignment was achieved. Beside the overall negative consequences of codon ambiguity, we demonstrated that codons that tolerate the loss of their cognate tRNA can also tolerate high Ser misincorporation. This raises the hypothesis that these codons can be reassigned to standard and eventually to new amino acids for the production of proteins with novel properties, contributing to the field of synthetic biology and biotechnology.

Ecological and biotechnological potential of sponge microbiome

Marine sponges harbor microbial communities of immense ecological and biotechnological importance. Recently, they have been focus of heightened attention due to the wide range of biologically active compounds with potential application, particularly, in chemical, cosmetic and pharmaceutical industries. However, we still lack fundamental knowledge of their microbial ecology and biotechnological potential. The development of high-throughput sequencing technologies has given rise to a new range of tools that can help us explore the biotechnological potential of sponges with incredible detail. Metagenomics, in particular, has the power to revolutionize the production of bioactive compounds produced by unculturable microorganisms. It can offer the identification of biosynthetic genes or gene clusters that can be heterologously expressed on a cultivable and suitable host. This review focus on the exploration of the biotechnological potential of sponge-associated microorganisms, and integration of molecular approaches, whose increasing efficiency can play an essential role on achieving a sustainable source of natural products.