ENS - Départment de biologie

Seth GRANT The architecture of synapse diversity in health and disease

Patricia Mangeny — 2026-05-11T09:00:00Z

11h

Le séminaire de Seth Grant (Edinburgh University, UK) aura lieu dans la salle des Résistants (1er étage, escalier A), 45 rue d'Ulm 75005 Paris

The brain's defining feature is its enormous number of synaptic connections. Traditionally, synapses were thought to fall into only a few broad classes—excitatory, inhibitory, or modulatory—based largely on neurotransmitter identity. The advent of synaptome mapping, which enables systematic, single-synapse–resolution analysis across the entire mouse brain, has overturned this view. These studies reveal an unexpectedly vast diversity of synapse types and their organisation into a highly structured three-dimensional map known as the synaptome architecture. This architecture provides a powerful new framework for understanding how innate and learned behaviours are encoded, how neurological and psychiatric diseases selectively target specific synapse populations, and how therapeutic drugs act on brain circuits. Our current work is focussing on the synaptome architecture of the human brain in health and disease.

Pierre BADUEL Transposable elements as vectors of allelic and- epiallelic exploration and their contribution to plant- genome evolution

Patricia Mangeny — 2026-05-05T12:00:00Z

14h
La soutenance HDR de Pierre Baduel (IBENS, équipe PEpiTE) aura lieu dans la salle Favard, IBENS 46 rue d'Ulm 75005 Paris

- 2026 / Soutenance d'HDR

Jacques WADICHE Local and diffuse actions of glutamate

Patricia Mangeny — 2026-04-27T09:00:00Z

11h

Le séminaire de Jacques Wadichet (University of Alabama at Birmingham Medical School) aura lieu dans la salle 316, IBENS 46 rue d'Ulm 75005 Paris

Glutamate signaling is often viewed as a highly local process in which transmitter released at anatomically defined synapses activates precisely aligned postsynaptic receptors. However, glutamate can also diffuse beyond the synaptic cleft, influencing nearby cells and receptors in ways that are not captured by classical wiring diagrams. In this talk, I will discuss how both local and diffuse glutamate signaling shape excitatory transmission in the cerebellar cortex. First, I will show that spillover from climbing fibers excites molecular layer interneurons (MLIs) through extrasynaptic mechanisms, functionally segregating interneurons according to their spatial relationship with the release site and altering inhibition of neighboring Purkinje cells. Next, I will describe how climbing fiber spillover can also recruit Ca2+-permeable AMPA receptors at parallel fiber synapses, revealing a form of “spill-in,” in which glutamate released from one pathway engages receptors associated with another. Finally, I will present evidence that the glutamate concentration landscape itself regulates key AMPA receptor properties, demonstrating that receptor behavior is shaped not only by subunit composition but also by the amount of glutamate reaching the receptor. Together, these findings support a broader view of excitatory signaling in which glutamate acts both locally and diffusely to influence receptors, synapses, and circuits.

Dr. David GREEN Positional cues, not Notch direct Neuroblast selection during early neurogenesis in the Drosophila embryo

Patricia Mangeny — 2026-04-17T09:00:00Z

11h à 12h
Le séminaire du Dr David Green (François Schweisguth's Lab, Institut Pasteur) aura lieu dans la salle Favard, IBENS 46 rue d'Ulm 75005 Paris

- 2026 / Séminaire de l'IBENS

Laura BARANELLO The interplay between transcription, topoisomerases and MYC

Patricia Mangeny — 2026-04-14T09:30:00Z

11h30
Le séminaire de Laura Baranello (Karolinska Institutet, Stockholm, Suède) aura lieu dans l'amphithéâtre Galois, 45 rue d'Ulm 75005 Paris

- 2026 / Séminaire de l'IBENS

Dr. Mikkel Winther PEDERSEN Ancient Environmental DNA and The Arrival of the Arctic Tundra Biome in Greenland

Patricia Mangeny — 2026-04-10T10:00:00Z

12h

Le séminaire du Dr. Mikkel Winther Pedersen (University of Copenhagen, Danemark) aura lieu dans la salle de Conférence, IBENS 46 rue d'Ulm 75005 Paris

Ancient environmental DNA (aeDNA) from silty basal ice at Camp Century (Greenland) documents tundra ecosystems preserved from at least two discrete Pleistocene interglacial intervals. Using shotgun metagenomics, DNA damage profiling, and molecular dating of chloroplast sequences, we resolve two temporally distinct depositional components : an older Lower Camp Century unit (Unit 1) with elevated damage and a younger Upper Camp Century suite (Units 2–5) with lower damage. Taxonomic assemblages shift vertically from Dryas-, Salix- and Saxifraga-dominated open shrub–herb tundra in Unit 1 to communities increasingly dominated by Cassiope, Saxifraga and mosses in overlying units ; intermittent signals of shallow freshwater macrophytes (Utricularia, Elatine, Hippuris) indicate local hydrological complexity during the younger interval. Together, these data provide some of the first direct molecular evidence that a fully tundra-dominated biome was not established in Greenland until mid-Pleistocene and that interglacial intervals supported internally differentiated tundra communities comparable to modern Arctic analogues. The Camp Century record highlights the value of subglacial archives for constraining ice-sheet retreat, ecosystem assembly, and the tempo of biome reorganization, and it suggests greater resilience and ecological plasticity of Arctic plant communities during past warmings, insights that bear on projections of future ecosystem responses to rapid climate change.

Ludmila LOKMANE Brain wiring : Development and Plasticity

Patricia Mangeny — 2026-04-08T12:00:00Z

14h
La soutenance d'HDR de Ludmila Lokmane (IBENS, équipe Garel) aura lieu dans la salle Favard, IBENS 46 rue d'Ulm 75005 Paris

- 2026

Stéphane MARCAND Mechanisms of Telomere End Protection

Patricia Mangeny — 2026-03-31T09:30:00Z

11h30
Le séminaire de Stéphane Marcand (CEA, Inserm, Univ. Paris-Saclay, Univ. Paris Cité, Fontenay-aux-Roses) aura lieu dans l'Amphithéâtre Galois, 45 rue d'Ulm 75005 Paris

- 2026 / Séminaire de l'IBENS

David CHAVALARIAS L'ère des dérèglements : climat, démocratie et ordre international

Patricia Mangeny — 2026-03-19T11:00:00Z

12h

Le séminaire de David Chavalarias (CNRS, EHESS, Institut des systèmes complexes) aura lieu dans la salle Favard, IBENS 46 rue d'Ulm 75005 Paris

Alors même que les conséquences du changement climatique et de l'effondrement de la biodiversité se font de plus en plus ressentir, la désinformation climatique en ligne et le climato-scepticisme dans l'opinion publique ont paradoxalement fortement progressé depuis 2022. Comment la désinformation climatique arrive-t-elle à gagner du terrain à contre-courant des faits ? Quels sont les profils de ses leaders et quelles sont les stratégies utilisées ? À partir de six années d'observation des échanges Twitter/"X" sur les questions climatiques (projet CNRS Climatoscope), nous aborderons ces questions tant d'un point de vue quantitatif que qualitatif, analysant au passage les effets systémiques des espaces numériques contemporains sur la circulation d'information au niveau global et in fine sur le débat public.

Michael HILLER Linking phenotypic differences between species to differences in their genome

Patricia Mangeny — 2026-03-17T10:30:00Z

11h30
Le séminaire de Michael Hiller (Senckenberg Research Institute, Francfort) aura lieu dans l'Amphithéâtre Galois, 45 rue d'Ulm 75005 Paris

- 2026 / Séminaire de l'IBENS