Robust gap repair in the contractile ring ensures timely completion of cytokinesis.

Cytokinesis in animal cells requires the constriction of an actomyosin contractile ring, whose architecture and mechanism remain poorly understood. We use laser microsurgery to explore the biophysical properties of constricting rings in Caenorhabditis elegans embryos. Laser cutting causes rings to snap open. However, instead of disintegrating, ring topology recovers and constriction proceeds. In response to severing, a finite gap forms and is repaired by recruitment of new material in an actin polymerization-dependent manner. An open ring is able to constrict, and rings repair from successive cuts. After gap repair, an increase in constriction velocity allows cytokinesis to complete at the same time as controls. Our analysis demonstrates that tension in the ring increases while net cortical tension at the site of ingression decreases throughout constriction and suggests that cytokinesis is accomplished by contractile modules that assemble and contract autonomously, enabling local repair of the actomyosin network. Consequently, cytokinesis is a highly robust process impervious to discontinuities in contractile ring structure.This project has received funding from the European Research Council (grants 640553, 260892, and 338410), Fundo Europeu de Desenvolvimento Regional (FED ER) funds through the Operational Competitiveness Program (COM PETE), national funds through Fundação para a Ciência e a Tecnologia (FCT) under the project FCO MP-01-0124-FED ER-028255 (PTDC/BEX-BCM/0654/2012), Fundação Luso-Americana para o Desenvolvimento Life Science 2020, and the Louis-Jeantet Young Investigator Award to H. Maiato. A.X. Carvalho, R. Gassmann, and I.A. Telley have FCT Investigator positions funded by FCT and cofunded by the European Social Fund through Programa Operacional Temático Potencial Type 4.2 promotion of scientific employment. A.M. Silva holds an FCT fellowship (SFRH/BPD/95707/2013). D.S. Osório was cofunded by the Programa Operacional Regional do Norte under the Quadro de Downloaded from jcb.rupress.org on February 27, 2018 Laser microsurgery in the contractile ring • Silva et al. 799 Referência Estratégico Nacional through FED ER and by FCT grant NOR TE-07-0124-FED ER-000003 (Cell Homeostasis Tissue Organization and Organism Biology)

COMPONENTES DO SANGUE E COAGULAÇÃO SANGUÍNEA

Todas as células do sangue são originadas do interior do osso na medula óssea vermelha e tem como função transporte de gases, nutrientes e hormônios, assim como a realização da coagulação sanguínea, da proteção contra  elementos  estranhos,  da  manutenção  da  temperatura  do  corpo,  da regulação do pH e da osmose

The teacher who teaches mathematics as a focus of study in Brazilian professional masters.

Neste artigo analisam-se 96 disserta??es, cujo foco ? o professor que ensina Matem?tica, produzidas nos mestrados profissionais da ?rea de Ensino da Capes, entre 2001 e 2012. Procura-se compreender como o pesquisador, que ? um professor, percebe os participantes de seu estudo e se relaciona com eles. O corpus da pesquisa foi analisado a partir das seguintes categorias: perfil do professor pesquisador e dos participantes; motiva??o e foco das pesquisas; e rela??o pesquisador-participantes. Os resultados evidenciam que, em muitos estudos, o professor (ou futuro professor), participante da pesquisa, ? percebido pelo pesquisador como um aprendiz, mais que como um parceiro ou colaborador. Isso sugere um distanciamento entre ambos que n?o condiz com o fato de pelo menos metade dos estudos mencionar que sua motiva??o adv?m das pr?prias trajet?rias profissionais. Al?m disso, poucas pesquisas analisam a pr?pria pr?tica do pesquisador ou refletem acerca de sua aprendizagem profissional ao realizar sua pesquisa.In this article, we analyzed 96 dissertations produced between 2001 to 2012 focused on the mathematics teacher by Professional Masters in the Teaching area of the Capes. The objective is to understand how a researcher, who is a teacher, perceives and relates to the participants of his studies. The data was analyzed from the following categories: profile of the researcher professor and of the participants; motivation and focus of research; and researcher-participant relationship. The results show how, in many cases, the teacher (or future teacher), who participated in the study it?s perceived as an apprentice rather than as a partner or collaborator. This suggests a gap between the two that does not match the fact that at least half of the studies mention that their motivation comes from their own professional trajectories. In addition, few researches analyze the researcher's own practice or reflect on his professional learning when conducting his research

Absence of Both IL-7 and IL-15 Severely Impairs the Development of CD8+ T Cell Response against Toxoplasma gondii

CD8+ T cells play an essential role in the protection against both acute as well as chronic Toxoplasma gondii infection. Although the role of IL-15 has been reported to be important for the development of long-term CD8+ T cell immunity against the pathogen, the simultaneous roles played by both IL-15 and related γ-chain family cytokine IL-7 in the generation of this response during acute phase of infection has not been described. We demonstrate that while lack of IL-7 or IL-15 alone has minimal impact on splenic CD8+ T cell maturation or effector function development during acute Toxoplasmosis, absence of both IL-7 and IL-15 only in the context of infection severely down-regulates the development of a potent CD8+ T cell response. This impairment is characterized by reduction in CD44 expression, IFN-γ production, proliferation and cytotoxicity. However, attenuated maturation and decreased effector functions in these mice are essentially downstream consequences of reduced number of antigen-specific CD8+ T cells. Interestingly, the absence of both cytokines did not impair initial CD8+ T cell generation but affected their survival and differentiation into memory phenotype IL-7Rαhi cells. Significantly lack of both cytokines severely affected expression of Bcl-2, an anti-apoptotic protein, but minimally affected proliferation. The overarching role played by these cytokines in eliciting a potent CD8+ T cell immunity against T. gondii infection is further evidenced by poor survival and high parasite burden in anti IL-7 treated IL-15−/− mice. These studies demonstrate that the two cytokines, IL-7 and IL-15, are exclusively important for the development of protective CD8+ T cell immune response against T. gondii. To the best of our knowledge this synergism between IL-7 and IL-15 in generating an optimal CD8+ T cell immunity against intracellular parasite or any other infectious disease model has not been previously reported

RNA secondary structure prediction from multi-aligned sequences

It has been well accepted that the RNA secondary structures of most functional non-coding RNAs (ncRNAs) are closely related to their functions and are conserved during evolution. Hence, prediction of conserved secondary structures from evolutionarily related sequences is one important task in RNA bioinformatics; the methods are useful not only to further functional analyses of ncRNAs but also to improve the accuracy of secondary structure predictions and to find novel functional RNAs from the genome. In this review, I focus on common secondary structure prediction from a given aligned RNA sequence, in which one secondary structure whose length is equal to that of the input alignment is predicted. I systematically review and classify existing tools and algorithms for the problem, by utilizing the information employed in the tools and by adopting a unified viewpoint based on maximum expected gain (MEG) estimators. I believe that this classification will allow a deeper understanding of each tool and provide users with useful information for selecting tools for common secondary structure predictions.Comment: A preprint of an invited review manuscript that will be published in a chapter of the book `Methods in Molecular Biology'. Note that this version of the manuscript may differ from the published versio