Molecular mechanisms of sexual development in basidiomycetes: exploring connections with lifestyles

Dissertação para obtenção do Grau de Doutor em BiologiaThis work concerns the investigation of the molecular mechanisms of sexual reproduction in fungi and their possible implication for fungal lifestyles (parasitic vs. saprobic) and for the emergence of asexual fungal lineages. The association between pathogenicity and sexuality is well-known in the basidiomycete plant parasite Ustilago maydis (subphylum Ustilaginomycotina), an economically important smut fungus. However, Ustilago species are phylogenetically interspersed with species of the genus Pseudozyma, which are considered saprobic and asexual. In this work, a study focused on genes involved in determining sexual identity (mating type or MAT genes), showed that Pseudozyma prolifica retains full sexual competence and pathogenicity, being therefore indistinguishable from U. maydis. For other Pseudozyma species, molecular analyses of PRF1, a gene that encodes a master regulator of sexual reproduction in U. maydis, showed no substantial evidence of loss of sexual reproduction. However, some clues were also found suggesting that some Pseudozyma species may be evolving towards a saprobic lifestyle. The earliest derived lineage of Basidiomycota (subphylum Pucciniomycotina) includes also important plant pathogens (rust and anther smut fungi) as well as lineages composed solely of saprobic organisms. Among the latter, the red yeasts of the order Sporidiobolales have the advantage of completing their life cycle in culture media, but have remained very little explored concerning the characterization of mating systems, the identification of MAT genes and the evolutionary relationships between sexual and asexual species. A comprehensive analysis of more than 200 strains belonging to 32 species of the Sporidiobolales indicated that asexuality seems to originate frequently from sexual lineages, but does not seem to persist long enough to form truly asexual species devoid of MAT genes. A more in-depth investigation of the red yeasts Rhodosporidium toruloides and Sporidiobolus salmonicolor allowed the identification for the first time in the Pucciniomycotina of the complete set of MAT genes. A detailed and multidisciplinary characterization of the mating system in the latter species yielded surprising results. A novel mating system that differs substantially from the two mating paradigms in basidiomycetes, the bipolar and tetrapolar systems, was brought to light. Given the basal phylogenetic position of the Pucciniomycotina within the Basidiomycota, this new system designated pseudo-bipolar, constitutes a significant contribution to the study of the evolution of MAT systems in fungi.Fundação para a Ciência e a Tecnologia - PhD grant(SFRH/BD/29580/2006

Spectral libraries and their uncertainties

Libraries of stellar spectra are fundamental tools in the study of stellar populations and in automatic determination of atmospheric parameters for large samples of observed stars. In the context of the present volume, here I give an overview of the current status of stellar spectral libraries from the perspective of stellar population modeling: what we have currently available, how good they are, and where we need further improvement

Adaptation of yeasts to fructose rich environments: a role for horizontal gene transfer of a fructose transporter

Abstract of the poster presented 33rd Small Meeting on Yeast Transport and Energetics, 21-24 July 2015, Lisbon, Portugal

The Potential of Unsaturated Polyesters in Biomedicine and Tissue Engineering: Synthesis, Structure-Properties Relationships and Additive Manufacturing

The success of Tissue Engineering (TE) based approaches is strongly dependent on the development of novel biomaterials for the design of 3D matrices with tailored biomechanical properties to promote the regeneration of human tissues and organs.This review covers the critical aspects related with the preparation of new unsaturated polyester (UP) resin formulations with suitable biological, chemical, thermal and morphological properties for the additive manufacturing (AM) of TE constructs. In this context, the basic principles of available AM technologies, with a special focus on novel stereolithography processes such as microstereolithography (micro-SLA), stereo-thermal-lithography (STLA), two-photon polymerization (TPP) and nanostereolithography (nano-SLA), are also presented and discussed. Ultimately, the present review will provide a better insight into the limitations and potential of combining UP and AM towards the rationale design/fabrication of complex artificial tissue substitute

ESEF 70 Anos: o processo de federalização sob o olhar discente

Artigo publicado na Revista MovimentoEste artigo analisa o processo de federalização da Escola de Educação Física da Universidade Federal do Rio Grande do Sul sob o olhar dos discentes que se graduaram em 1970 na primeira turma formada sob o regime federal de ensino. Fundamentada no aporte teórico da História Cultural analisamos aspectos relacionados ao envolvimento político dos alunos nesse processo bem como aspectos relacionados a estrutura e funcionamento da Escola como um todo. Para tanto, recorremos a História Oral entrevistando discentes e docentes do período bem como analisamos fontes de diversa natureza tais como documentos, atas de reuniões, livros, reportagens de jornal, fotografia entre outras. Da análise realizada apreendemos que esta turma vivenciou a federalização de modo muito peculiar: por dentro do processo, mas, em certa medida, muito afastada dele.Produção decorrente do projeto "ESCOLA DE EDUCAÇÃO FÍSICA DA UNIVERSIDADE FEDERAL DO RIO GRANDE DO SUL (1940-2010): mapeando cenários da formação profissional e da produção do conhecimento em políticas públicas de esporte e lazer", financiado pela Rede Cede

Modeling the ecology and evolution of biodiversity: Biogeographical cradles, museums, and graves

Individual processes shaping geographical patterns of biodiversity are increasingly understood, but their complex interactions on broad spatial and temporal scales remain beyond the reach of analytical models and traditional experiments. To meet this challenge, we built a spatially explicit, mechanistic simulation model implementing adaptation, range shifts, fragmentation, speciation, dispersal, competition, and extinction, driven by modeled climates of the past 800,000 years in South America. Experimental topographic smoothing confirmed the impact of climate heterogeneity on diversification. The simulations identified regions and episodes of speciation (cradles), persistence (museums), and extinction (graves). Although the simulations had no target pattern and were not parameterized with empirical data, emerging richness maps closely resembled contemporary maps for major taxa, confirming powerful roles for evolution and diversification driven by topography and climate

The untapped Australasian diversity of astaxanthin-producing yeasts with biotechnological potential—Phaffia Australis sp. nov. and Phaffia tasmanica sp. nov.

PTDC/BIA-MIC/30785/2017 UIDB/04378/2020 NIH/NIAID R37 MERIT Award AI39115-23 NIH/NIAID R01 AI50113-16Phaffia is an orange-colored basidiomycetous yeast genus of the order Cystofilobasidiales that contains a single species, P. rhodozyma. This species is the only fungus known to produce the economically relevant carotenoid astaxanthin. Although Phaffia was originally found in the Northern hemisphere, its diversity in the southern part of the globe has been shown to be much greater. Here we analyze the genomes of two Australasian lineages that are markedly distinct from P. rhodozyma. The two divergent lineages were investigated within a comprehensive phylogenomic study of representatives of the Cystofilobasidiales that supported the recognition of two novel Phaffia species, for which we propose the names of P. australis sp. nov. and P. tasmanica sp. nov. Comparative genomics and other analyses confirmed that the two new species have the typical Phaffia hallmark—the six genes necessary for the biosynthesis of astaxanthin could be retrieved from the draft genome sequences, and this carotenoid was detected in culture extracts. In addition, the organization of the mating-type (MAT) loci is similar to that of P. rhodozyma, with synteny throughout most regions. Moreover, cases of trans-specific polymorphism involving pheromone receptor genes and pheromone precursor proteins in the three Phaffia species, together with their shared homothallism, provide additional support for their classification in a single genus.publishersversionpublishe

Functionality of the paracoccidioides mating α-pheromone-receptor system

Recent evidence suggests that Paracoccidioides species have the potential to undergo sexual reproduction, although no sexual cycle has been identified either in nature or under laboratory conditions. In the present work we detected low expression levels of the heterothallic MAT loci genes MAT1-1 and MAT1-2, the a-pheromone (PBa) gene, and the a- and apheromone receptor (PREB and PREA) genes in yeast and mycelia forms of several Paracoccidioides isolates. None of the genes were expressed in a mating type dependent manner. Stimulation of P. brasiliensis MAT1-2 strains with the synthetic a pheromone peptide failed to elicit transcriptional activation of MAT1-2, PREB or STE12, suggesting that the strains tested are insensitive to a-pheromone. In order to further evaluate the biological functionality of the pair a-pheromone and its receptor, we took advantage of the heterologous expression of these Paracoccidioides genes in the corresponding S. cerevisiae null mutants. We show that S. cerevisiae strains heterologously expressing PREB respond to Pba pheromone either isolated from Paracoccidioides culture supernatants or in its synthetic form, both by shmoo formation and by growth and cell cycle arrests. This allowed us to conclude that Paracoccidioides species secrete an active a-pheromone into the culture medium that is able to activate its cognate receptor. Moreover, expression of PREB or PBa in the corresponding null mutants of S. cerevisiae restored mating in these non-fertile strains. Taken together, our data demonstrate pheromone signaling activation by the Paracoccidioides a-pheromone through its receptor in this yeast model, which provides novel evidence for the existence of a functional mating signaling system in Paracoccidioides.MHJS and JFM were supported by Fundacão para a Ciência e Tecnologia (FCT) grants. This work was supported by a grant from FCT (PTDC/BIA-MIC/ 108309/2008)

Desenvolvimento de uma proposta experimental controlada remotamente para o estudo de fenômenos ópticos

This work aims to propose and evaluate the educational impact of a remotely controlled experiment aimed at teaching physics at a high level in the study of concepts related to the reflection and refraction of light phenomena. For this purpose, we applied this activity in comparison to another performed in person in five different classes of students in the second year of high school and we applied a pre-test and a post-test, to compare the difference in performance. The results show contributions to student learning, as well as the development of some important competences from the procedural and attitudinal point of view of the students.Este trabalho tem o objetivo de propor e avaliar o impacto educacional de um experimento controlado remotamente voltado para o ensino de Física em nível médio no estudo dos conceitos relativos aos fenômenos de reflexão e refração da luz. Para tanto aplicamos tal atividade em comparação a outra realizada presencialmente em cinco turmas diferentes de alunos do segundo ano do Ensino Médioe aplicamos um pré-teste e um pós-teste, para comparamos a diferença de desempenho. Os resultados evidenciam contribuições para a aprendizagem dos estudantes, bem como o desenvolvimento de algumas competências importantes do ponto de vista procedimental e atitudinal dos alunos

Sr ISOTOPES BY LA-MC-ICP-MS PROCEDURES COUPLED WITH THE MACS3 REFERENCE MATERIAL IN A CORAL SAMPLE: A RECORD OF ENVIRONMENTAL CHANGES: Isótopos de Sr analisados por LA-MC-ICP-MS como material de referência MACS3 em uma amostra de coral: um registro de mudanças ambientais

The main aim of this work is to demonstrate that the Laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) is a powerful tool for the analysis of strontium (Sr) isotopes in corals. This work discusses certification strategies for Sr isotopes determination, using reference material (RM) analyses and the results treatment based on detailed data acquired in biological materials, a coral sample. To obtain reliable results, it is essential to properly adjust the mass spectrometer and laser ablation system. Adjusting the equipment to its maximum intensity does not always result in correct 87Sr/86Sr ratios. Therefore, the optimization of the mass spectrometer was performed using the reference material NIST SRM-987 (solution) and adjusting the correct Sr isotope ratio to the reference material (USGS MACS3 and NIST-612, solids) before each analytical session. The protocol applied the solid reference material USGS MACS3 with an isotopic ratio 87Sr/86Sr of 0.72000. The values obtained for this RM varied between 0.7012 and 0.7014, with a correction factor calculated between 0.990 and 0.988. In order to account for potential drifts in the mass spectrometer during an analytical session, the application of bracketing correction and the use of the most convenient reference material are suggested. The analytical uncertainty of Sr data obtained by LA-MC-ICP-MS is comparable to studies carried out on other carbonate materials. The results of ablation techniques are reproducible within the analytical error, which implies that this technique produces robust results when applied to coral carbonates. In addition, several comparative measurements of different reference materials (e.g. USGS MACS3 and NIST 612) and the comparison of the 87Sr/86Sr ratios highlight the robustness of the method. The results along the coral growth axes showed a decrease in the 87Sr/86Sr ratio from the inner to the outer layer of the coral (from 0.70920 to 0.70627), which indicate variations in the availability of particulate matter during the coral growth, probably related to local marine environmental changes.- O objetivo principal deste trabalho é demonstrar que a espectrometria de massa com plasma indutivamente acoplado e ablação a laser (LA-MC-ICP-MS) é uma ferramenta poderosa para a análise de isótopos de Sr em corais. Este trabalho discute estratégias de certificação para determinação de isótopos de Sr, usando análises de material de referência e o detalhamento do tratamento dos resultados adquiridos em materiais biológicos (coral). Para obter resultados confiáveis, é essencial ajustar adequadamente o espectrômetro de massas e o sistema de ablação a laser de forma a obter a intensidade máxima e em seguida promover as correções para obter as razões 87Sr / 86Sr corretas. Nestes termos, a otimização do espectrômetro de massa foi realizada usando o material de referência NIST SRM-987 (em solução) que em sequência foi migrado para a ablação a laser com ajuste da razão isotópica Sr correta para o material de referência (NIST-612, vidro), antes de cada sessão analítica. O protocolo incluiu a utilização material de referência sólido USGS MACS3 com razão isotópica 87Sr / 86Sr de 0,72000. Os valores obtidos para esta RM variaram entre 0,7012 e 0,7014, com fator de correção calculado entre 0,990 e 0,988. A fim de contabilizar possíveis desvios no espectrômetro de massa durante uma sessão analítica, sugere-se a aplicação de correção de bracketing e o uso do material de referência com a mesma matriz. Os resultados das técnicas de ablação são reproduzíveis dentro do erro analítico, o que indica que esta técnica produz resultados robustos quando aplicada a carbonatos de coral. Além disso, várias medições comparativas de diferentes materiais de referência (por exemplo, USGS MACS3 e NIST 612) e a comparação das suas respectivas razões 87Sr / 86Sr destacam a robustez do método. Os resultados ao longo dos eixos de crescimento do coral mostraram uma diminuição na razão 87Sr / 86Sr da camada interna para a externa do coral (de 0,70920 para 0,70627). Estes resultados sugerem variações na disponibilidade de material particulado durante o crescimento do coral, provavelmente relacionado a mudanças ambientais marinhas locais. Palavras-chave: Carbonato biológico. Isótopos de Sr. LA-MC-ICP-MS. Materiais de referência. Metodologia. Ambiente marinho. &nbsp