Thesis Directors: Prof. F. Rachidi-Haeri, Prof. M. Rubinstein
\r\nPhysics doctoral program
\r\nThesis Nr. 11764
Memories are not static representations but evolve over time through consolidation and their progressive reorganization across distributed brain networks. This process allows memories to remain persistent while also becoming sufficiently flexible to guide behavior in novel situations. In this seminar, Gisella Vetere will discuss how memory engrams are reorganized from learning to remote recall and how distinct neuronal ensembles contribute to the balance between memory specificity and generalization. Combining activity-dependent neuronal tagging, circuit manipulations, and brain-wide analyses, her research seeks to uncover how memories are transformed over time and how these transformations shape adaptive—and potentially maladaptive—behavior.
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An opportunity to celebrate the end of the year and share quantum research at EPFL with one another and the larger community. The event will include short lectures on topics in quantum for the general community, optional lab visits, and food and drinks!
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\r\nFull program and registration available in October
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\r\nINVITED SPEAKER:
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\r\nAdvancing Multidimensional Single-Molecule localization microscopy: development and applications in nuclear organization
\r\nDr. Bassam Hajj, Institut Curie, Paris
\r\nHost: Prof. Aleksandra Radenovic
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\r\nAbstract:
\r\nSingle-molecule localization microscopy (SMLM) has revolutionized our understanding of biological processes by providing access to spatial scales beyond the diffraction limit of conventional optical microscopy. In the study of the cell nucleus, SMLM has offered unique insights into its organization and function at the nanoscale. Nuclear architecture is structured across multiple spatial scales in three dimensions and is highly dynamic. Understanding the mechanisms that govern nuclear organization therefore requires imaging approaches capable of capturing molecular dynamics across a broad range of spatial and temporal scales and in diverse biological contexts. Although SMLM can routinely achieve spatial resolutions in the tens-of-nanometers range, many biologically relevant structures and processes remain beyond its reach. For example, resolving the precise organization of DNA at the molecular scale remains challenging, as it would require a substantial improvement in spatial resolution over conventional SMLM, while also addressing the high density and degree of molecular compaction within the nucleus.
\r\nOver the years, we have developed complementary strategies to address these challenges by introducing additional dimensions and observables into SMLM measurements. In this presentation, I will first discuss our approaches to three-dimensional single-molecule imaging, including multifocus microscopy and volumetric light-sheet excitation, which enable fast and sensitive imaging over extended volumes and in complex biological samples such as cell colonies. While these approaches provide access to the three-dimensional and temporal dimensions required to investigate nuclear organization, spatial resolution alone is not always sufficient to distinguish molecular arrangements. We have therefore extended SMLM further by implementing polarization-resolved multifocus microscopy (PolMFM), which combines three-dimensional localization with information on molecular orientation.
\r\nI will illustrate how these multidimensional approaches can provide new insights into nuclear organization, with examples spanning different biological systems. In particular, I will present evidence for a long-range, crystal-like organization of DNA within the nuclei of mature sperm cells from crickets, demonstrating how multidimensional imaging can reveal structural features that remain inaccessible to conventional localization microscopy.
\r\nFinally, I will discuss the challenges and opportunities associated with visualizing, analyzing, and interactively exploring the multidimensional datasets generated by these approaches. Together, these developments illustrate how extending SMLM beyond conventional two-dimensional localization can provide new ways to interrogate the organization and dynamics of biological systems at the nanoscale.
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\r\nBio:
\r\nBassam Hajj is a physicist and CNRS researcher at Institut Curie in Paris, where he is a member of the Physics of Cells and Cancer unit and co-leads the “Light-based Observation and Control of Cellular Organization” team. His research focuses on the development of advanced optical microscopy techniques, particularly single-molecule localization microscopy, 3D imaging, and multidimensional approaches for studying cellular organization at the nanoscale.
\r\nAfter completing his PhD at École Normale Supérieure de Cachan on electro-optical microscopy, Bassam joined Janelia Research Campus as a postdoctoral researcher, where he worked on multifocus microscopy for fast and sensitive single-molecule imaging. He subsequently returned to Institut Curie and joined the CNRS as a permanent researcher in 2016.
\r\nHis current research combines innovative microscopy, quantitative image analysis, and data visualization to investigate molecular organization and dynamics, with a particular focus on nuclear organization.
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\r\nSTUDENT SPEAKER:
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\r\nTranscription Factor Dose in Stem Cell Reprogramming: Insights from Single-Cell Multi-Omics
\r\nAngelika Gebhart, Deplancke Lab
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\r\nBioEngineering Talks mandatory EDBB Seminar Attendance (1st-Year PhD Students)\r\n
Weekly BioEngineering Talks (Lunch Provided)
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\r\nINVITED SPEAKER:
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\r\nDe novo design of light-responsive proteins
\r\nDr. Alexander Hilditch, EPFL Laboratory of Protein Design & Immunoengineering
\r\nHost: Prof. Bruno Correia
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\r\nBioEngineering Talks mandatory EDBB Seminar Attendance (1st-Year PhD Students)\r\n