Physical mapping of a powdery mildew resistance related gene Hv-S/TPK by FISH with a TAC clone in wheat

Dissertação de mestrado integrado em Medicina (Hematologia), apresentado á Faculdade de Medicina da Universidade de Coimbra.A Policitemia Vera (PV) é uma doença clonal de etiologia desconhecida, na maior parte dos casos, que envolve a célula estaminal progenitora hematopoiética multipotencial. É uma neoplasia mieloproliferativa crónica (NMP) que se caracteriza pela expansão das três linhas celulares hematopoiéticas: eritróide, granulocítica e megacariocítica, com predomínio da primeira, de modo independente dos mecanismos normais de regulação da eritropoiese. Além disso, as células têm aspecto morfológico normal, a fibrose medular é pouco significativa e os níveis de eritropoietina (Epo) são habitualmente normais a baixos. Além da hipercelularidade medular com sobreprodução de uma ou de todas as linhas celulares, a doença cursa com hematopoiese extramedular, hiperviscosidade, propensão para complicações como trombose ou hemorragia e risco de desenvolvimento de mielofibrose ou transformação em leucemia aguda. A descrição relativamente recente da associação de uma mutação no gene JAK2, localizado no cromosoma 9p24, com as doenças mieloproliferativas clássicas negativas para BCR-ABL, como a PV, veio permitir avanços significativos na compreensão da patofisiologia deste grupo de doenças hematológicas. A mutação provoca uma alteração do aminoácido V (valina) para F (fenilalanina) na posição 617 (JAK2V617F). De acordo com os dados publicados, a frequência da detecção da mutação JAK2V617F em doentes com PV é de cerca de 95%. A proteína JAK2 é uma tirosina cinase citoplasmática, que se encontra associada ao domínio intracelular dos receptores de citocinas (como a Epo e trombopoietina - Tpo), e de factores de crescimento, essenciais para a função destes receptores. A mutação da JAK2 conduz à activação constitutiva dos receptores, independente da ligação à respectiva citocina e/ou hipersensibilidade a factores de crescimento, com consequente activação de múltiplas vias de sinalização intracelulares como a JAK/STAT (Janus Kinase/Signal Transductor and activator of transcription), a PI3K (fosfatidilinositol 3 cinase) e a MAPK (proteína cinase activadora de mitose), envolvidas na transformação e proliferação dos progenitores hematopoiéticos. Por outro lado, as células evidenciam alteração na diferenciação terminal e resistência à apoptose in vitro que poderá estar relacionada com o aumento da expressão da proteína anti-apoptótica Bcl-XL. Além dos avanços no diagnóstico, a detecção da mutação JAK2V617F tem contribuido para melhorar a classificação e a terapêutica dos doentes com PV. Deste modo, o conhecimento dos mecanismos moleculares envolvidos na PV tem levado os investigadores à descoberta de novos fármacos dirigidos ao defeito molecular, permitindo novas abordagem terapêuticas mais eficazes e provavelmente de menor toxicidade. Este trabalho procura fazer uma revisão sobre o actual conhecimento da caracterização molecular e clínica da PV e quais as suas implicações no diagnóstico e abordagem terapêutica desta NMP.Polycythemia Vera (PV) is a clonal disease of unknown etiology, which often involves the pluripotential hematopoietic stem cell. This disease integrates the family of chronic myeloproliferative neoplasm (MPN) and is characterized by the growth of the three hematopoietic celular lineages: granulocytic, megakaryocytic and erythroid, with predominance of the last one and regardless the normal mechanisms of erythropoiesis regulation. Moreover, cells have normal morphological aspect, bone marrow shows slight fibrosis and the levels of erythropoietin (Epo) usually vary from normal to low. Besides marrow hypercellularity with overproduction of one or all the celular lineages, the disease courses with extramedullary hematopoiesis, hyperviscosity, leading to complications such as thrombosis or bleeding and risk of transformation to myelofibrosis or acute leukemia. Recently it has been described the association between the mutation in the JAK2 gene, located on chromosome 9p24, with the classic myeloproliferative disorders BCR-ABL negative, such as PV, which has brought significant advances in the understanding of the pathophysiology of this group of hematologic malignancies. The mutation causes a change of amino acid V (valine) to F (phenylalanine) at position 617 (JAK2V617F). According to published data, the frequency of JAK2V617F mutation detected in patients with PV is about 95%. JAK2 protein is a cytoplasmic tyrosine kinase, which is associated to the intracelular domain of cytokine receptors, such as Epo and thrombopoietin (Tpo), and growth factors which are essential to the function of these receptors. JAK2 mutation leads to the constitutive receptors activation, independent of connection to their cytokine and / or hypersensitivity to growth factors, with consequent activation of multiple intracellular signaling pathways such as JAK / STAT (Janus Kinase / Signal transducer and transcription activator), the PI3K (phosphatidylinositol 3 kinase) and MAPK (Mitogen-activated protein), involved in the transformation and proliferation of hematopoietic progenitors. Moreover, the cells show changes in terminal differentiation and resistance to in vitro apoptosis which is possibly related to the increasing expression of anti-apoptotic protein Bcl-XL. In addition to the advances in diagnosis, detection of JAK2V617F mutation has contributed to the improvement of classification and treatment in patients with PV. Thus, knowledge of the molecular mechanisms involved in PV has led investigators to the discovery of new drugs targeting molecular defects, allowing new therapeutic approach more efficient and probably less toxic. The aim of this article is to review the current knowledge of clinical and molecular characterization of PV, and its implications on the diagnosis and therapeutic approach of this myeloproliferative disorder

Effect of bainite layer by LSMCIT on wear resistance of medium-carbon bainite steel at different temperatures

In this work, bainite layer was prepared by Laser surface melting combined with isothermal treatment (LSMCIT) at 250ºC. The microstructures of the samples were analyzed by scanning electron microscopy (SEM), X-ray Diffraction (XRD) and transmission electron microscopy (TEM). Their wear resistances at 20ºC, 100ºC and 200ºC were measured using reciprocating tribometer. After the wear test, the confocal laser scanning microscope and SEM were used to characterize the topography of all abrasion surfaces, and the phase transformations occurred on the contact surfaces were analyzed by XRD. The results show that the microstructure of the LSMCIT sample has been refined to nanoscale. The wear volume reduction ratio of LSMCIT sample is 40.9% at 20ºC. The wear resistances of the samples are decreased with increasing of the temperature, however, the decrease in amplitude of the bainite is relatively small. The harder surface of the LSMCIT sample can provides higher mechanical support, and the white-etching layer on surface are difficult to remove by the reciprocating friction. The wear resistances of the LSMCIT samples at 20ºC, 100ºC and 200ºC are excellent, which shows the wide temperature ranges in wear applications

Air monitoring for illegal drugs including new psychoactive substances: A review of trends, techniques and thermal degradation products

The detection of illicit psychotropic substances in both indoor and outdoor air is a challenging analytical discipline and the data from such investigation may provide intelligence in a variety of fields. Applications of drug monitoring in air include providing data on national and international drug consumption trends, as monitored by organisations such as the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) and the United Nations Office on Drugs and Crime (UNODC). Air monitoring enables mapping of illicit drug manufacturing, dealing or consumption in cities and the identification of emergent compounds including the recent proliferation of new psychoactive substances (NPS). The rapid spread of NPS has changed the global drug market with greater diversity and dynamic spread of such compounds over several nations. This review provides an up to date analysis of key thematic areas within this analytical discipline. The process of how illicit psychotropic substances spread from emission sources to the atmosphere is considered alongside the sampling and analytical procedures involved. Applications of the technique applied globally are reviewed with studies ranging from the analysis of individual dwellings through to major international air monitoring campaigns providing evidence on global drug trends. Finally, we consider thermal breakdown products of illicit psychotropic substances including NPS that are released upon heating, combustion or vaping and related potential for exposure to these compounds in the air

Update on HER-2 as a target for cancer therapy: The ERBB2 promoter and its exploitation for cancer treatment

Overexpression of the ERBB2 proto-oncogene is associated with amplification of the gene in breast cancer but increased activity of the promoter also plays a significant role. Members of two transcription factor families (AP-2 and Ets) show increased binding to the promoter in over-expressing cells. Consequently, strategies have been devised to target promoter activity, either through the DNA binding sites for these factors, or through another promoter sequence, a polypurine-polypyrimidine repeat structure. The promoter has also been exploited for its tumour-specific activity to direct the accumulation of cytotoxic compounds selectively within cancer cells. Our current understanding of the ERBB2 promoter is reviewed and the status of these therapeutic avenues is discussed

Synergistic Effect of Functionalized Nickel Nanoparticles and Quercetin on Inhibition of the SMMC-7721 Cells Proliferation

The effect of functionalized nickel (Ni) nanoparticles capped with positively charged tetraheptylammonium on cellular uptake of drug quercetin into hepatocellular carcinoma cells (SMMC-7721) has been explored in this study via microscopy and electrochemical characterization as well as MTT assay. Meanwhile, the influence of Ni nanoparticles and/or quercetin on cell proliferation has been further evaluated by the real-time cell electronic sensing (RT-CES) study. Our observations indicate that Ni nanoparticles could efficiently improve the permeability of cancer cell membrane, and remarkably enhance the accumulation of quercetin in SMMC-7721 cells, suggesting that Ni nanoparticles and quercetin would facilitate the synergistic effect on inhibiting proliferation of cancer cells

Gains in QTL Detection Using an Ultra-High Density SNP Map Based on Population Sequencing Relative to Traditional RFLP/SSR Markers

Huge efforts have been invested in the last two decades to dissect the genetic bases of complex traits including yields of many crop plants, through quantitative trait locus (QTL) analyses. However, almost all the studies were based on linkage maps constructed using low-throughput molecular markers, e.g. restriction fragment length polymorphisms (RFLPs) and simple sequence repeats (SSRs), thus are mostly of low density and not able to provide precise and complete information about the numbers and locations of the genes or QTLs controlling the traits. In this study, we constructed an ultra-high density genetic map based on high quality single nucleotide polymorphisms (SNPs) from low-coverage sequences of a recombinant inbred line (RIL) population of rice, generated using new sequencing technology. The quality of the map was assessed by validating the positions of several cloned genes including GS3 and GW5/qSW5, two major QTLs for grain length and grain width respectively, and OsC1, a qualitative trait locus for pigmentation. In all the cases the loci could be precisely resolved to the bins where the genes are located, indicating high quality and accuracy of the map. The SNP map was used to perform QTL analysis for yield and three yield-component traits, number of tillers per plant, number of grains per panicle and grain weight, using data from field trials conducted over years, in comparison to QTL mapping based on RFLPs/SSRs. The SNP map detected more QTLs especially for grain weight, with precise map locations, demonstrating advantages in detecting power and resolution relative to the RFLP/SSR map. Thus this study provided an example for ultra-high density map construction using sequencing technology. Moreover, the results obtained are helpful for understanding the genetic bases of the yield traits and for fine mapping and cloning of QTLs