Ensino e pesquisa no segundo grau

A autora relata experiência em escola de segundo grau através de projeto de ensino-pesquisa. O objetivo é estimular os alunos e capacitá-los para a auto-aprendizagem, buscando o aprimoramento de conhecimentos. Durante um semestre, cerca de duzentos alunos aprenderam o que é um projeto de pesquisa, as etapas da pesquisa científica e desenvolveram projetos, chegando a resultados bastante satisfatórios, expostos pela escola com vistas à integração com a comunidade.The author reports on an experiment carried out by a high school using the teaching-research project. The objective is to stimulate the students and capacitate them for self-teaching, aiming at improving knowledge. During one semester, some two hundred students learned what a research project is, the stages of scientific research and they developed projects, reaching rather satisfactory results, exhibited by the school aiming at integrating itself with the community

The Elg1-RFC Clamp-Loading Complex Performs a Role in Sister Chromatid Cohesion

It is widely accepted that of the four Replication Factor C (RFC) complexes (defined by the associations of either Rfc1p, Ctf18p, Elg1p or Rad24p with Rfc2p-Rfc5p), only Ctf18-RFC functions in sister chromatid cohesion. This model is based on findings that CTF18 deletion is lethal in combination with mutations in either CTF7ECO1 or MCD1 sister chromatid cohesion genes and that ctf18 mutant cells exhibit cohesion defects. Here, we report that Elg1-RFC not only participates in cohesion but performs a function that is distinct from that of Ctf18-RFC. The results show that deletion of ELG1 rescues both ctf7eco1 mutant cell temperature sensitivity and cohesion defects. Moreover, over-expression of ELG1 enhances ctf7eco1 mutant cell phenotypes. These findings suggest that the balance of Ctf7pEco1p activity depends on both Ctf18-RFC and Elg1-RFC. We also report that ELG1 deletion produces cohesion defects and intensifies the conditional phenotype of mcd1 mutant cells, further supporting a role for Elg1-RFC in cohesion. Attesting to the specificity of these interactions, deletion of RAD24 neither suppressed nor exacerbated cohesion defects in either ctf7eco1 or mcd1 mutant cells. While parallel analyses failed to uncover a similar role in cohesion for Rad24-RFC, it is well known that Rad24-RFC, Elg1-RFC and Ctf18-RFC play key roles in DNA damage responses. We tested and found that Ctf7pEco1p plays a significant role in Rad24-RFC-based DNA response pathways. In combination, these findings challenge current views and document new and distinct roles for RFC complexes in cohesion and for Ctf7pEco1p in DNA repair

The SUN Protein Mps3 Is Required for Spindle Pole Body Insertion into the Nuclear Membrane and Nuclear Envelope Homeostasis

The budding yeast spindle pole body (SPB) is anchored in the nuclear envelope so that it can simultaneously nucleate both nuclear and cytoplasmic microtubules. During SPB duplication, the newly formed SPB is inserted into the nuclear membrane. The mechanism of SPB insertion is poorly understood but likely involves the action of integral membrane proteins to mediate changes in the nuclear envelope itself, such as fusion of the inner and outer nuclear membranes. Analysis of the functional domains of the budding yeast SUN protein and SPB component Mps3 revealed that most regions are not essential for growth or SPB duplication under wild-type conditions. However, a novel dominant allele in the P-loop region, MPS3-G186K, displays defects in multiple steps in SPB duplication, including SPB insertion, indicating a previously unknown role for Mps3 in this step of SPB assembly. Characterization of the MPS3-G186K mutant by electron microscopy revealed severe over-proliferation of the inner nuclear membrane, which could be rescued by altering the characteristics of the nuclear envelope using both chemical and genetic methods. Lipid profiling revealed that cells lacking MPS3 contain abnormal amounts of certain types of polar and neutral lipids, and deletion or mutation of MPS3 can suppress growth defects associated with inhibition of sterol biosynthesis, suggesting that Mps3 directly affects lipid homeostasis. Therefore, we propose that Mps3 facilitates insertion of SPBs in the nuclear membrane by modulating nuclear envelope composition

Principles of chromosomal organization: lessons from yeast

The spatial organization of genes and chromosomes plays an important role in the regulation of several DNA processes. However, the principles and forces underlying this nonrandom organization are mostly unknown. Despite its small dimension, and thanks to new imaging and biochemical techniques, studies of the budding yeast nucleus have led to significant insights into chromosome arrangement and dynamics. The dynamic organization of the yeast genome during interphase argues for both the physical properties of the chromatin fiber and specific molecular interactions as drivers of nuclear order

Meiotic Chromosome Pairing Is Promoted by Telomere-Led Chromosome Movements Independent of Bouquet Formation

Chromosome pairing in meiotic prophase is a prerequisite for the high fidelity of chromosome segregation that haploidizes the genome prior to gamete formation. In the budding yeast Saccharomyces cerevisiae, as in most multicellular eukaryotes, homologous pairing at the cytological level reflects the contemporaneous search for homology at the molecular level, where DNA double-strand broken ends find and interact with templates for repair on homologous chromosomes. Synapsis (synaptonemal complex formation) stabilizes pairing and supports DNA repair. The bouquet stage, where telomeres have formed a transient single cluster early in meiotic prophase, and telomere-promoted rapid meiotic prophase chromosome movements (RPMs) are prominent temporal correlates of pairing and synapsis. The bouquet has long been thought to contribute to the kinetics of pairing, but the individual roles of bouquet and RPMs are difficult to assess because of common dependencies. For example, in budding yeast RPMs and bouquet both require the broadly conserved SUN protein Mps3 as well as Ndj1 and Csm4, which link telomeres to the cytoskeleton through the intact nuclear envelope. We find that mutants in these genes provide a graded series of RPM activity: wild-type>mps3-dCC>mps3-dAR>ndj1Δ>mps3-dNT = csm4Δ. Pairing rates are directly correlated with RPM activity even though only wild-type forms a bouquet, suggesting that RPMs promote homologous pairing directly while the bouquet plays at most a minor role in Saccharomyces cerevisiae. A new collision trap assay demonstrates that RPMs generate homologous and heterologous chromosome collisions in or before the earliest stages of prophase, suggesting that RPMs contribute to pairing by stirring the nuclear contents to aid the recombination-mediated homology search

Silent chromatin at the middle and ends: lessons from yeasts

Eukaryotic centromeres and telomeres are specialized chromosomal regions that share one common characteristic: their underlying DNA sequences are assembled into heritably repressed chromatin. Silent chromatin in budding and fission yeast is composed of fundamentally divergent proteins tat assemble very different chromatin structures. However, the ultimate behaviour of silent chromatin and the pathways that assemble it seem strikingly similar among Saccharomyces cerevisiae (S. cerevisiae), Schizosaccharomyces pombe (S. pombe) and other eukaryotes. Thus, studies in both yeasts have been instrumental in dissecting the mechanisms that establish and maintain silent chromatin in eukaryotes, contributing substantially to our understanding of epigenetic processes. In this review, we discuss current models for the generation of heterochromatic domains at centromeres and telomeres in the two yeast species

Anchoring a Leviathan: How the Nuclear Membrane Tethers the Genome

It is well established that the nuclear envelope has many distinct direct connections to chromatin that contribute to genome organization. The functional consequences of genome organization on gene regulation are less clear. Even less understood is how interactions of lamins and nuclear envelope transmembrane proteins (NETs) with chromatin can produce anchoring tethers that can withstand the physical forces of and on the genome. Chromosomes are the largest molecules in the cell, making megadalton protein structures like the nuclear pore complexes and ribosomes seem small by comparison. Thus to withstand strong forces from chromosome dynamics an anchoring tether is likely to be much more complex than a single protein-protein or protein-DNA interaction. Here we will briefly review known NE-genome interactions that likely contribute to spatial genome organization, postulate in the context of experimental data how these anchoring tethers contribute to gene regulation, and posit several hypotheses for the physical nature of these tethers that need to be investigated experimentally. Significantly, disruption of these anchoring tethers and the subsequent consequences for gene regulation could explain how mutations in nuclear envelope proteins cause diseases ranging from muscular dystrophy to lipodystrophy to premature ageing progeroid syndromes. The two favored hypotheses for nuclear envelope protein involvement in disease are 1) weakening nuclear and cellular mechanical stability, and 2) disrupting genome organization and gene regulation. Considerable experimental support has been obtained for both. The integration of both mechanical and gene expression defects in the disruption of anchoring tethers could provide a unifying hypothesis consistent with both

The crisis of the Russian family in the works of Dostoevsky, Tolstoy and Chekhov.

This thesis examines the crisis of the Russian family through the eyes of the key Russian writers of the second half of the 19th century: Tolstoy (1828-1910), Dostoevsky (1821-1881), and Chekhov (1860-1904). The purpose of this thesis is to demonstrate that the works of these authors are not just novels or short stories about the crisis of the family, but representative of the societal situation in Russia at the time. The aim of this study is also to show the continuity in ideas between these authors in the context of family life and marriage and to explore what kind of solutions they envisioned for the future of the Russian family. Although there has been extensive research on the family in the works of these great classics of 19th century Russian literature, there has been less analysis of the crisis of the Russian family and the solutions they offered as a way out of the crisis. Hence the aim of this research is to fill this critical gap. The first chapter focuses on the representation of family life in Dostoevsky’s latest works The Brothers Karamazov (1881), “The Dream of a Ridiculous Man” (1877), and The Diary of a Writer (1876-7). The second chapter examines Tolstoy’s The Kreutzer Sonata (1889) and The Power of Darkness (1886). Tolstoy focuses his attention on both upper classes and the peasant family. Chapter three analyses the crisis of the family in some of Chekhov’s short stories and novellas that are particularly concerned with extra marital relations and marriages gone badly; they also address mistreatment of children. This thesis argues that, on the one hand, these authors depict different types of marriages and family relations, and, on the other hand, their works reflect the changing realities and attitudes regarding love and sexuality of their time. It also argues that, through their fiction and sometimes in a subversive way, these authors influenced the readers’ mentality and came up with new radical ideas about the future of the Russian family. Finally, this thesis aims to bring more academic interest to an overlooked research area, to explore how family values change through the eyes of these authors, and to contribute to a broader understanding of the crisis and the future of the Russian family through the lenses of the key Russian writers of 19th century Russia

Evitare le ferite, prima difesa contro Valsa ceratosperma sul pero: il punto su conoscenze biologiche ed epidemiologiche e difesa

A distanza di otto anni dal ritrovamento di Valsa ceratosperma in pereti della regione Emilia Romagna, si cerca di fare il punto sulla conoscenze biologiche ed epidemiologiche del patogeno e sulle possibilit\ue0 di difes

Efficacy evaluation of copper formulations for the control of lettuce downy mildew (Bremia lactucae)

A four-year field trial was run to determine the effectiveness of copper fungicides and foliar fertilizers in controlling lettuce downy mildew (Bremia lactucae Regel) in Italy’s Emilia-Romagna Region. The experimental design was randomized blocks with 4 replicates using the highly susceptible Camaro cultivar. Eleven different fungicide formulae and foliar fertilizers with low copper concentration were compared. Tribasic copper sulphate (Cuproxat S.D.I.), copper sulphate (Poltiglia Caffaro 20) and copper oxychloride (Pasta Caffaro Nc) exhibited the best control; the effects of pentahydrate sulphate (Kay Tee) and hydroxyde (Kocide 2000) were less consistent. Hydroxide sulphate (Poltiglia disperses), tribasic sulphate (Cuproxat liquido) and the Special Kopper were less effective. The action of the foliar dressings Kendal TE, Fertileader rame and Labicuper showed the most promising results. The only non-copper-based alternative product, grapefruit seed extract, or DF 100 V, proved to be ineffective. Some of the tested foliar sprays were thus as effective as some copper-based fungicides and released less copper into the environment