Collège de France

Ant colonies depend heavily on chemical communication, creating demanding problems for sensory gene regulation. This lecture examines the expansion of olfactory-receptor gene families and the mechanisms that select a receptor for each neuron. Comparisons with vertebrates illuminate how stochastic gene choices support organised sensory systems.

This lecture examines the development and evolution of insect learning centres. It asks how expanded neuronal populations and cell-type diversity support the behaviour of social species such as ants. Mechanisms in insect mushroom bodies are compared with changes in the mammalian cortex.

The superfluid fraction measures how much of a fluid supports frictionless motion. This seminar studies low-temperature systems in which external potentials tune that fraction and transport measurements quantify it. For an equilibrium, weakly interacting Bose condensate, the researchers also extract the fraction from a single density image. The approach offers a new measurement route for investigating recently realized supersolid phases.

This lecture uses the fruit-fly visual system to examine how neuronal diversity emerges from developing stem cells. Differences between the timing of cell division and developmental progression can produce varied cell lineages. The discussion considers how related principles might help explain diversity in the mammalian cortex and retina.

This lecture asks how developing brains generate many distinct neuronal types. It examines the contribution of a stem cell's spatial origin and its changing developmental state. Work in simpler nervous systems provides molecular examples that can inform the study of human cortical development.

Preventing biological invasions requires coordinated action before and after organisms arrive. This seminar examines the regulatory frameworks, biosecurity practices, public education and collective action used to reduce introductions and manage invasive species.

Carbocation-mediated substitution commonly loses stereochemical information and competes with elimination or rearrangement. This seminar describes a strategy using nonclassical carbocations to make SN1 transformations predictable, selecting either inversion or retention. It addresses acyclic products with adjacent stereocentres and controlled regio-, diastereo- and enantioselectivity, then shows how carbon–carbon bond rearrangements can install stereodefined bonds away from the initial cation while tolerating sensitive functional groups.

Agriculture and urban development threaten soil processes that sustain biodiversity, nutrient cycling, water regulation and climate resilience. The seminar examines how ecosystem-based interventions can restore soils, and why soil health must itself be built into the design of those interventions. Examples from the SOLU-BIOD research programme in France and abroad connect ecological restoration with food and water security. The discussion also considers practical barriers to adoption and the public policies needed to support implementation.

Disease emergence reflects interacting changes in land use, intensive livestock production and biodiversity. This seminar brings those relationships together rather than treating each driver separately. It examines One Health and Planetary Health responses to health crises, then considers place-based approaches that use ecosystems and biodiversity, including community-managed forests.

Two presentations examine selective nitrogen installation in organic molecules. The first studies how changing rhodium nitrene catalysts can direct amination toward different carbon–hydrogen bonds, including normally unreactive sites, beyond the limits of substrate-directed approaches. The second addresses the sustainability problems of scarce metals and conventional nitrene precursors through iron catalysts and hydroxylamine derivatives. Applications include aziridination, alkene difunctionalization within and between molecules, and direct carbon–hydrogen functionalization without an additional external oxidant.

Free N-heterocyclic carbenes are modest reductants, but their reactions with suitable electrophiles can produce exceptionally strong organic electron donors. The seminar explains how electron-rich structures and stabilization after oxidation enable single- and double-electron transfers, and how structural changes tune reduction potentials. It connects mechanistic understanding with radical synthesis and emerging uses in materials, greenhouse-gas chemistry and energy conversion or storage.

This lecture examines genetic control of tail length using variation between deer-mouse populations and targeted experiments. It considers multiple quantitative-trait loci, the possible role of Hoxd13 expression and evidence from altered Hox13 activity. Vertebral development provides a case study of how changes in gene regulation can produce evolutionary changes in body form.

The first presentation develops doubly metalated organozinc reagents whose two nucleophilic sites can react sequentially. Examples include silyl- and germylzincation of alkynes, rearrangements producing metalated allenes and enantioselective activation of geminal diorganozincs. The second examines nitrogen extrusion as a driving force for carbanion formation. It surveys synthetic applications and describes decomposition of silylated diazenes to obtain group-one organometallic reagents with tertiary alkyl centres.

This lecture compares two approaches to the evolution of mammalian tails. It critically examines the proposed role of altered Tbxt splicing in ape tail loss, including difficulties interpreting mouse experiments. It then introduces quantitative-genetic studies of deer mice in different habitats, where several loci contribute to variation in tail length.

This seminar connects molecular chirality with the reactivity of cations and their precursors. Helical structures based on delocalized triarylcarbenium frameworks provide a platform for tuning electronic and chiroptical properties. A second focus is metal-catalysed decomposition of diazocarbonyl compounds, yielding ylides and elaborated heterocycles. The discussion includes tetrahetero-substituted methanes with unusually persistent configurations and relates their resistance to enantiomerization to carbocation chemistry.

Jérôme Chave examines how tropical forests respond to warming and rising carbon dioxide. Their carbon uptake is constrained by physiology, ecological interactions and extreme conditions. Long-term field observations, analytical methods and models are used to investigate future carbon storage, biodiversity and the persistence of forest communities under global change.

This lecture traces research on the mouse T locus and the Tbxt gene before examining a proposed mechanism of tail loss in apes. A repeated DNA insertion may alter splicing and protein production. The discussion asks how a small genetic change could affect development and generate a large, persistent evolutionary transformation.

Tail development provides a case study for connecting genetic change to the evolution of anatomy. This lecture introduces relevant ideas from evolutionary developmental biology and RNA splicing, then considers variation in tail presence and length across mammals. It also examines what different experimental approaches can establish about DNA, form and function.

Tracy Northup explains how interactions between trapped atomic ions and single photons transfer quantum information between matter and light. Atom–photon entanglement can connect distant ions, as demonstrated by a prototype linking calcium ions across 230 metres. The seminar considers how larger networks could support secure communications, distributed computation and connected quantum sensors.

Quantum networks require links between stored qubits and information carried by travelling waves. This lecture compares interfaces coupling atoms, spins and superconducting circuits to optical or acoustic signals. It also introduces quantum memories, the measurements used to assess their performance, recent experimental results and applications that combine communication with quantum processing.