Solos vulcânicos : vulnerabilidade à poluição agrícola

A secção UAciência é coordenada pelo Professor Universitário Armindo Rodrigues.[…]. A aplicação de agroquímicos (pesticidas, fertilizantes orgânicos e inorgânicos) nas culturas e solos é uma prática comum na agricultura. Estes químicos agrícolas possuem concentrações variáveis de metais como o cádmio, níquel, lítio, chumbo, arsénio, zinco, cobre, entre outros, que são introduzidos artificialmente nas formulações químicas ou presentes como contaminantes das mesmas. A necessidade de maximização da produtividade é preocupação constante quando se transforma a agricultura numa actividade empresarial. No entanto, dada a natureza imutável dos metais e as propriedades adsorventes dos solos vulcânicos, existe uma tendência para a acumulação destas substâncias potencialmente tóxicas. É a natureza vulcânica dos solos açorianos que os coloca em situação de vulnerabilidade à poluição e, neste caso, a agricultura é apontada como a principal fonte de input de metais pesados nestes solos. […].info:eu-repo/semantics/publishedVersio

Resistência a antibióticos : um problema de saúde pública, animal e ambiental

A secção UAciência é coordenada pelo Professor Universitário Armindo Rodrigues.A resistência aos antibióticos é uma ameaça emergente à saúde que necessita de um esforço global para combater os riscos para a saúde humana, animal e ambiental. A produção de resistência ocorre quando um antibiótico perde a capacidade de controlar eficazmente o crescimento de um grupo de bactérias para o qual foi criado, sendo que estas continuam a multiplicar-se, mesmo na presença de doses terapêuticas do fármaco. O desenvolvimento de resistência é um fenómeno natural que resulta da pressão seletiva exercida pelo uso de antibióticos. As bactérias podem ser naturalmente resistentes aos antibióticos ou podem adquirir resistência por duas vias: 1) por mutação genética ou 2) por aquisição de genes de resistência de outra bactéria. Uma bactéria resistente a antibióticos passa esta característica às gerações seguintes, formando-se uma população resistente. A presença do antibiótico funciona como um agente de pressão seletiva, inibindo a atividade de bactérias suscetíveis e favorecendo a sobrevivência de estirpes resistentes. Este é um clássico exemplo da teoria da seleção natural de Charles Darwin. […].info:eu-repo/semantics/publishedVersio

Diagnóstico das infeções fúngicas invasivas: metodologias atuais e emergentes

Trabalho Final de Mestrado Integrado, Ciências Farmacêuticas, 2020, Universidade de Lisboa, Faculdade de Farmácia.As infeções fúngicas invasivas são um problema de saúde emergente em todo o mundo, associadas um aumento na taxa de mortalidade e de morbilidade, e que por isso, requerem uma atenção especial por parte da comunidade médica e científica. O aumento destas infeções tem sido predominantemente impulsionado pela adoção crescente de terapias imunossupressoras em certas populações de pacientes e pelo uso mais recorrente de dispositivos invasivos, como cateteres venosos centrais. O uso de novos medicamentos modificadores da imunidade também abriu um espectro inteiramente novo de pacientes com risco para infeções fúngicas invasivas. Apesar de, na maioria dos casos, existir terapêutica adequada, a principal adversidade destas infeções resulta da dificuldade em diagnosticar correta e atempadamente o agente etiológico responsável, devido à falta de métodos padronizados prontos a serem utilizados na prática clínica. O foco principal deste trabalho está no grupo de fungos responsáveis pela maioria das infeções fúngicas invasivas, os géneros Candida e Aspergillus, e fungos da ordem Mucorales. Os métodos de diagnóstico atuais incluem tomografia computorizada, exame microbiológico direto, cultura, histopatologia, biomarcadores fúngicos (como o galactomanano e o β-D-glucano) e PCR. Porém, nenhum destes, por si só, tem especificidade e/ou sensibilidade suficientes para obter um diagnóstico fidedigno, por isso, a melhor estratégia, reside na utilização combinada destes. Técnicas de diagnóstico molecular para as infeções fúngicas invasivas têm estado na vanguarda deste tema. Apesar de ainda em desenvolvimento, e com falta de estudos em larga escala e padronização, métodos moleculares são capazes de diagnosticar infeções fúngicas invasivas, quando os métodos tradicionais não o conseguem, e quando é necessário um resultado rápido e preciso.Invasive fungal infections are an emerging health problem worldwide, which is associated with an increased rate of mortality and morbidity, therefore requiring special attention from the medical and scientific community. The increase in these infections has been predominantly driven by the increasing adoption of immunosuppressive therapies in certain patient populations and by the more recurrent use of invasive devices, such as central venous catheters. The use of new immunity-modifying drugs has also opened an entirely new spectrum of patients at risk for invasive fungal infections. Although, in most cases, there is adequate therapy, the main adversity results from the difficulty in correctly and timely diagnosing the responsible etiologic agent, due to the lack of standardized methods ready to be used in clinical practice. The main focus of this work is on the group of fungi responsible for most invasive fungal infections, the genera Candida and Aspergillus, and fungi of the order Mucorales. Current diagnostic methods include computed tomography, direct microbiological examination, culture, histopathology, fungal biomarkers (such as galactomannan and β-D-glucan) and PCR. However, none of these, on their own, has sufficient specificity and/or sensitivity to obtain a reliable diagnosis, therefore, the best strategy lies in the combined use of these. Molecular diagnostic techniques for invasive fungal infections have been at the forefront of this topic. Although still under development, and with a lack of large-scale studies and standardization, molecular methods are able to diagnose invasive fungal infections, when traditional methods fail, and when a fast and accurate result is needed

Solos vulcânicos : um tesouro negro

A secção UAciência é coordenada pelo Professor Universitário Armindo Rodrigues.[…]. A agricultura constitui, desde sempre, um pilar fundamental da economia açoriana, tendo moldado a nossa paisagem de tal forma que e quase impossível dissociar a agricultura do solo que esta na sua base. Atualmente a agricultura, os agricultores e a indústria enfrentam grandes desafios – o de produzir produtos de qualidade, com valor acrescentado e de uma forma ambientalmente sustentável. Estes são, sem dúvida, desafios que pressupõem um esforço global – novas formas de pensar e de produzir, inevitavelmente ajustadas a particularidade dos nossos recursos naturais. A solução poderá estar debaixo dos nossos pés, nos nossos solos. Por exemplo, os solos vulcânicos da ilha de São Miguel possuem um perfil biogeoquímico caracterizado por elevadas concentrações de micronutrientes como zinco, selénio, cobre e manganês, muitos deles numa forma bio disponível. […].info:eu-repo/semantics/publishedVersio

Main soil contaminants and their fate in the soil environment

Soil pollution is invisible to the human eye, but it compromises the quality of the food we eat, the water we drink, and the air we breathe and puts human and environmental health at risk. Most contaminants originate from human activities such as industrial processes and mining, poor waste management, unsustainable farming practices, accidents ranging from small chemical spills to accidents at nuclear power plants, and the many effects of armed conflicts. Pollution knows no borders: contaminants are spread throughout terrestrial and aquatic ecosystems and many are distributed globally by atmospheric transport. In addition, they are redistributed through the global economy by way of food and production chains. 
 
 Soil pollution has been internationally recognized as a major threat to soil health, and it affects the soil’s ability to provide ecosystem services, including the production of safe and sufficient food, compromising global food security. Soil pollution hinders the achievement of many of the United Nations Sustainable Development Goals (SDGs), including those related to poverty elimination (SDG 1), zero hunger (SDG 2), and good health and well-being (SDG 3). Soil pollution hits the most vulnerable hardest, especially children and women (SDG 5). The supply of safe drinking water is threatened by the leaching of contaminants into groundwater and runoff (SDG 6). CO2 and N2O emissions from unsustainably managed soils accelerate climate change (SDG 13). Soil pollution contributes to land degradation and loss of terrestrial (SDG 15) and aquatic (SDG 14) biodiversity, and decreased the security and resilience of cities (SDG 11), among others

Biological endpoints in earthworms (Amynthas gracilis) as tools for the ecotoxicity assessment of soils from livestock production systems

Due to the intensification and modernization of livestock farming practices, large amounts of trace metals, veterinary pharmaceuticals and pesticide residues are released to the soil along with animal feces. Hence, there is an increasing concern about the effects of pollutants derived from livestock activities on soil organisms. The objective of this study is to assess the ecotoxicity of soils from livestock production systems using a set of validated tissue and cellular biomarkers of non-native earthworms (Amynthas gracilis) exposed ex situ to real contaminated livestock soils. Overall, the results showed that livestock pollutants present clear environmental risks, since the exposure during 14 days to soils from livestock systems triggered significant sub-lethal effects in A. gracilis, revealed by the increase of acetylcholinesterase activity in earthworms’ tissues (from 34.15 ± 0.79 to 62.74 ± 2.10 nmol of acetylthiocholine hydrolyzed min−1 mg−1 of protein), the decrease of antioxidant defense associated enzymes (superoxide dismutase activity, from 2.76 ± 0.11 to 1.90 ± 0.04 U mg−1 of protein) and of lysosomal integrity (neutral red uptake, from 113.00 ± 4.81 to 83.73 ± 2.25%). Moreover, coelomocytes of earthworms exposed to the livestock soil displayed significantly higher DNA damage values (comet assay, from 126.67 ± 8.67 to 199.67 ± 23.15 GDI). This study validates the applicability of the tested biomarkers as early warning tools to assess sub-lethal toxicity to organisms inhabiting soil impacted by livestock pollutants. This study also highlights the relevance of A. gracilis as a suitable sentinel species to provide an integrative and more ecologically relevant response of soil ecosystem health in livestock production systems

Disruption of genomic neighbourhood at the imprinted IGF2-H19 locus in Beckwith–Wiedemann syndrome and Silver–Russell syndrome

Hyper- and hypomethylation at the IGF2-H19 imprinting control region (ICR) result in reciprocal changes in IGF2-H19 expression and the two contrasting growth disorders, Beckwith–Wiedemann syndrome (BWS) and Silver–Russell syndrome (SRS). DNA methylation of the ICR controls the reciprocal imprinting of IGF2 and H19 by preventing the binding of the insulator protein, CTCF. We here show that local changes in histone modifications and CTCF–cohesin binding at the ICR in BWS and SRS together with DNA methylation correlate with the higher order chromatin structure at the locus. In lymphoblastoid cells from control individuals, we found the repressive histone H3K9me3 and H4K20me3 marks associated with the methylated paternal ICR allele and the bivalent H3K4me2/H3K27me3 mark together with H3K9ac and CTCF–cohesin associated with the non-methylated maternal allele. In patient-derived cell lines, the mat/pat asymmetric distribution of these epigenetic marks was lost with H3K9me3 and H4K20me3 becoming biallelic in the BWS and H3K4me2, H3K27me3 and H3K9ac together with CTCF–cohesin becoming biallelic in the SRS. We further show that in BWS and SRS cells, there is opposing chromatin looping conformation mediated by CTCF–cohesin binding sites surrounding the locus. In normal cells, lack of CTCF–cohesin binding at the paternal ICR is associated with monoallelic interaction between two CTCF sites flanking the locus. CTCF–cohesin binding at the maternal ICR blocks this interaction by associating with the CTCF site downstream of the enhancers. The two alternative chromatin conformations are differently favoured in BWS and SRS likely predisposing the locus to the activation of IGF2 or H19, respectively

Long-range chromatin interactions at the mouse Igf2/H19 locus reveal a novel paternally expressed long non-coding RNA

Parental genomic imprinting at the Igf2/H19 locus is controlled by a methylation-sensitive CTCF insulator that prevents the access of downstream enhancers to the Igf2 gene on the maternal chromosome. However, on the paternal chromosome, it remains unclear whether long-range interactions with the enhancers are restricted to the Igf2 promoters or whether they encompass the entire gene body. Here, using the quantitative chromosome conformation capture assay, we show that, in the mouse liver, the endodermal enhancers have low contact frequencies with the Igf2 promoters but display, on the paternal chromosome, strong interactions with the intragenic differentially methylated regions 1 and 2. Interestingly, we found that enhancers also interact with a so-far poorly characterized intergenic region of the locus that produces a novel imprinted long non-coding transcript that we named the paternally expressed Igf2/H19 intergenic transcript (PIHit) RNA. PIHit is expressed exclusively from the paternal chromosome, contains a novel discrete differentially methylated region in a highly conserved sequence and, surprisingly, does not require an intact ICR/H19 gene region for its imprinting. Altogether, our data reveal a novel imprinted domain in the Igf2/H19 locus and lead us to propose a model for chromatin folding of this locus on the paternal chromosome

An insulator element 3′ to the CFTR gene binds CTCF and reveals an active chromatin hub in primary cells

Regulation of expression of the CFTR gene is poorly understood. Elements within the basal promoter of the gene do not fully explain CFTR expression patterns, suggesting that cis-regulatory elements are located elsewhere, either within the locus or in adjacent chromatin. We previously mapped DNase I hypersensitive sites (DHS) in 400 kb spanning the CFTR locus including a cluster of sites close to the 3′-end of the gene. Here we focus on a DHS at +6.8 kb from the CFTR translation end-point to evaluate its potential role in regulating expression of the gene. This DHS, which encompasses a consensus CTCF-binding site, was evident in primary human epididymis cells that express abundant CFTR mRNA. We show by DNase I footprinting and electophoretic mobility shift assays that the cis-regulatory element within this DHS binds CTCF in vitro. We further demonstrate that the element functions as an enhancer blocker in a well-established in vivo assay, and by using chromatin immunoprecipitation that it recruits CTCF in vivo. Moreover, we reveal that in primary epididymis cells, the +6.8 kb DHS interacts closely with the CFTR promoter, suggesting that the CFTR locus exists in a looped conformation, characteristic of an active chromatin hub