Affichage des résultats 1621 à 1640 sur 1677 au total
Benjamin Guinet, ex-doctorant au LBBE, reçoit un prix décerné par la Société française de Virologie pour sa thèse soutenue en 2023 sur les virus endogènes chez les insectes Hyménoptères.
Biological networks of large dimensions, with their diagram of interactions, are often well represented by a Boolean model with a family of logical rules. An advantage of Boolean and discrete modelling is the possibility of fully characterizing all qualitative dynamical trajectories of a particular network, based simply on the structure of links and interactions between nodes. A biological network may have different qualitative behaviours in response to different conditions. For instance, in response to different inputs, the system may have a single steady state, or multiple steady states, or exhibit oscillatory behaviour. In this context, using the asynchronous transition graph of the Boolean network, we have developed a method for identifying the groups of active or operational interactions that are responsible for a given dynamic behaviour.As an example, a model of an apoptosis network will be analysed. Two core groups of elements and interactions are identified: they correspond to two different mechanisms that may be used by the cell for the decision between apoptosis or cell survival.
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The turn from the 20th to the 21st Century was marked by a drastic change in the scale at which biologists study regulatory networks. In the 1990, a PhD student could spend years analysing the regulation of one particular gene by one or a few transcription factors. Microarray technologies enabled monitoring the expression of all the genes of an organism in a single experiment (transcriptome arrays), and to lead genome-wide location analysis to report supposedly exhaustive lists of transcription factor binding sites. Next Generation Sequencing amplified the movement, and many labs are now combining ChIP-seq and RNA-seq experiments to get a wide view on transcription factor binding locations, histone modifications, and transcriptional responses to a multitude of conditions, cell types, developmental stages, etc. In the first part of the talk, I will present some of the bioinformatics approaches and tools that we developed to analyse regulatory motifs from various types of high-throughput data (e.g. co-expression clusters, ChIP-seq peaks, replication origins).At the light of the evolution of the domain, I would also like to address a more general question about the insights gained from high-throughput approaches on fundamental mechanisms of regulation. Indeed, it implicitly became standard to consider that a typical high-throughput experiments should return thousands of significant features (differentially expressed genes, TF binding sites, active enhancers). This however does not fit with our classical models, were transcription factors would turn on or off specific sets of target genes ("regulatory switches"), thereby forming regulatory networks whose behaviour was understandably determined by feedback loops. How can we conciliate the undeniable robustness of regulatory networks with the apparent noisiness of binding and transcription profiles?
Laure Ségurel, aujourd’hui chercheuse au LBBE (et précédemment au Musée de l’Homme) a contribué à éclairer l’histoire évolutive de la digestion du lait
Le mardi 29 septembre à 14h, sur France Inter, Marion Valeix était l’invitée de Mathieu Vidard et son émission la Terre au Carré, à l’occasion de la sortie sur Canal + du film d’Alexandre Soullier « Le Roi Bâtard » sur le lion d’Afrique. Les travaux de Marion Valeix portent plus généralement sur les communautés de grands mammifères africains et le rôle des interactions interspécifiques dans le fonctionnement de celles-ci.
Thèse Cecilia Coimbra Klein - mardi 12 novembre 2013 à 14 h 30, amphithéâtre CNRS
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