As the 2025 edition of the France-BioImaging Image Contest is still running, we wanted to highlight our previous winners and their projects. Here is a quick throwback to our 2024 winners.

Before getting to the heart of the matter, we want to remind you that you still have time (before November 14th) to submit your best images and try to win your registration fees for one 2026 microscopy-related event! Please make sure you upload your images on the following link:

FBI Image Contest 2025

  • Learn more about our 2024 France-BioImaging Image Contest winners!

    As the 2025 edition of the France-BioImaging Image Contest is still running, we wanted to highlight our previous winners and their projects. Here is a quick throwback to our 2024 winners. Before getting to the heart of the matter, we want to remind you that you still have time (before November 14th) to submit your…

Last year, we enjoyed the winning images submitted for their artistic take and their quality. Thanks to Vanessa WEICHSELBERGER , Dalia EL ARAWI and Frédéric FERCOQ for their beautiful images!

1st Place: Vanessa WEICHSELBERGER

Pierre-François LENNE team, Institut de Biologie du Développement de Marseille (IBDM)

“Rays of repetitive beauty”

Marine plant collected in Mediterranean Sea, stained for Actin using Phalloidin.

2-photon microscope

Vanessa WEICHSELBERGER is a shared post-doctoral researcher between the lab of Pierre-François LENNE at IBDM in Marseille and Vikas TRIVEDI at EMBL in Barcelona. She is a developmental biologist and interested in how cells coordinate morphogenetic processes with each other.

The image she submitted isn’t related to her research proejct. It is of a sample that they took from the Mediterranean Sea on a lab day out, it is part of an underwater plant. She believes it stands for their interest in shape and form beyond their own research projects. It represents their broad curiosity in biological structures.

They stained the sample for Actin and Nuclei and just admired its structure, pattern and periodicity.

“It is a great example of how amazing all kind of life is!“

By multiplying and arranging the image into a periodic wheel, the periodicity of the sample itself is even more highlighted.

2nd Place: Dalia EL ARAWI

Pierre-François LENNE team, Institut de Biologie du Développement de Marseille (IBDM)

“Gastrula Nebula”

Murine embryonic organoid illustrating cells collective migration on a laminin-coated surface. Phalloidin-labeled Actin filaments and Hoechst-stained Nuclei highlight detailed cellular architecture and a remarkably structured tissue organization.

Zeiss LSM 880 Confocal Microscopy

Dalia EL ARAWI is a post-doctoral researcher in biophysics, currently working at the IBDM in Marseille. Her research focuses on studying Gastruloids, 3D aggregates of mouse embryonic stem cells.

Gastruloids have emerged as a powerful in vitro model to study early embryonic development and tissue patterning. Within a few days, Gastruloids undergo symmetry breaking, axial elongation and germ layers specification, forming structures that closely mimic embryonic tissues both genetically and morphologically. Despite their ability to self-organize into complex architectures, 3D Gastruloids face developmental limitations over time, including tissue surface tension, apoptosis, and high phenotypic variability. To address these challenges, she used a hybrid 2.5D Gastruloids approach: first, generating 3D Gastruloids with proper differentiation and antero-posterior symmetry breaking, then transferring them onto a 2D extracellular matrix that mimics extraembryonic tissues, promoting more advanced morphogenesis.

This is illustrated in the submitted image, where a 2.5D Gastruloid spreads across a laminin-coated surface, revealing detailed cellular architecture and tissue organization. By applying different labeling strategies, she uses this approach to gain insights into vascular and cardiac structure formation. Her findings suggest that substrate-guided Gastruloid models may potentially recapitulate key aspects of cardiovascular development, offering new insights into tissue self-organization and vascularization.

For Dalia, being awarded second place in the FBI Image Contest was very rewarding. The recognition increased the visibility of her work, sparked discussions with colleagues inside and outside the lab, and motivated her to present her research more widely. It also gave her confidence to pursue future opportunities related to microscopy and imaging!

3rd Place: Frédéric FERCOQ

Molecules of Communication and Adaptation of Microorganisms team, Museum National d’Histoire Naturelle (MNHN)

“Explosion filarienne“

Internal architecture of Litomosoides sigmodontis, a parasitic nematode used as a model to better understand filarial infections. Under significant internal pressure to maintain its structure, this nematode experienced a cuticle rupture during handling, leading to the expulsion of some organs, including the ovary and intestine. The cytoskeleton appears in orange, and the DNA in cyan.

Confocal microscopy

Frédéric FERCOQ is a Maître de conférences in the UMR 7245 “Molecules of Communication and Adaptation of Microorganisms” at the MNHN in Paris. He works in the “Parasites and Free-Living Protists” team, where his research focuses on host–parasite–symbiont interactions during filarial infections. He studies how anti-parasite immune responses and bacterial endosymbionts such as Wolbachia influence parasite development, fertility, and tissue pathology. Microscopy is central to his approach, enabling him to visualize parasite structure, host tissue organization, and cellular interactions in detail.

The submitted image shows the internal anatomy of a female Litomosoides sigmodontis filarial worm after mechanical rupture. Due to the high internal pressure required to maintain its structure, the cuticle burst during manipulation, causing the expulsion of internal tissues, here the ovaries and intestine. Tubulin staining (orange) highlights microtubule-rich structures, while DNA is shown in cyan.

Winning the FBI Image Contest allowed Frédéric to attend the Microscience Microscopy Congress (MMC Series) in Manchester in July 2024, where he presented both a poster and an oral communication. The MMC is one of Europe’s leading interdisciplinary conferences dedicated to advances in microscopy across the life and physical sciences. It was a great opportunity for him to share their most recent publication (https://doi.org/10.1371/journal.ppat.1013301) and to present it in the context of their broader, microscopy-driven research on filarial development and host–parasite interactions. The event also allowed him to connect with researchers from diverse imaging backgrounds and explore new techniques relevant to parasitology.

Want to be the next winner of our FBI Image Contest? Apply through the following link before November 14th, 2025: https://france-bioimaging.org/fbi-special-events/fbi-image-contest-2025/

The brain: a network of neurons… and supporting cells

Our brain is made up of neurons…but not only neurons! Neurons are specialized cells that transmit information to other cells, whether nerve or non-nerve. Information travels as electrical impulses along the axon, a sort of “highway” that carries the nerve signal.

At the end of each axon are synapses, small communication zones composed of:

  • the axon terminal of the presynaptic neuron (which sends the signal),
  • the membrane of the postsynaptic neuron (which receives it),
  • and the synaptic cleft, the narrow gap where neurotransmitters are released to pass the message.

To keep neurons functioning properly, the brain also contains glial cells, which provide structural and metabolic support and regulate many physiological processes. Among them are astrocytes, star-shaped cells located close to synapses.

Since the 1990s and the discovery of the “tripartite synapse” concept, scientists have revealed the crucial role astrocytes play in information transmission.

However, astrocytes still hold some secrets, particularly concerning their finest extensions, called “leaflets”!

Cutting-edge imaging strategies for unprecedented results

To explore the structure and function of astrocytes in greater detail, the authors developed an innovative multimodal imaging workflow, combining two-photon and electron microscopy.

The electron microscopy experiments were led by several France-BioImaging units: CEA-Grenoble, Grenoble Institute of Neurosciences and the TIMC laboratory. The 2-photon imaging was performed at Lausanne University.

  • FIB-SEM microscopy to reveal the 3D ultrastructure of astrocytes and, in particular, their leaflets. This technique was combined with 3D immunolabeling to detect the presence of specific proteins:
  • IP₃R1, a marker of the endoplasmic reticulum involved in calcium signaling, 
  • Connexin-43, a protein found at gap junctions connecting different structures.
  • 2-photon calcium imaging to monitor real-time calcium variations in live leaflets in 3D, thereby assessing their role in cell-to-cell communication.

Architecture of the leaflets

Leaflets are extremely thin extensions (<250 nm), sometimes smaller than the wavelength of visible light, which explains why they long escaped direct observation.

They contain tiny segments of endoplasmic reticulum (i-ER) but no mitochondria, indicating a specialization for rapid and localized calcium signaling.

Several leaflets are interconnected via gap junctions, forming micro-networks within the astrocyte.

Figure 1. Leaflets are complex subdomains of the astrocyte interconnected by gap junctions. (B) Top: segmentation of a complete astrocyte fragment, including: bottom left: shafts with inner diameter >250 nm (gray); bottom right: leaflets, ≤250 nm (green). Bars: 3 μm.

Figure 3. i-ER: Minuscule organelles observed specifically in the leaflet domains of astrocytes. (C) Examples of i-ER saccules (magenta overlaid to EM images). Top: i-ERs surrounded by associated ribosomes (magenta arrowheads). Bottom: i-ERs contacting the astrocyte plasma membrane (yellow arrowheads). Bar: 500 nm.

Interaction with synapses

3D reconstructions revealed that the majority of synapses (around 90%) are shared by several leaflets of a single astrocyte.

Thus, one astrocyte can link together multiple synapses within the same neuronal network.

This finding challenges the “one synapse ↔ one astrocyte” model: in reality, astrocytes connect neurons to one another through their leaflets.

Figure 2. Leaflets are the astrocyte’s specialized subdomains that interact with synapses and preferentially embed multiple vs. individual synapses. (B) Arrangement of synaptic elements with leaflets and other astrocyte structures; 2D FIB-SEM images overlaid with segmentation map (leaflet: green; axonal bouton: yellow; spine: orange; synaptic cleft: red). Left: five synapses encompassed in a leaflet domain, contacted by leaflet units. Bar: 0.5 μm. Top right: synapse in direct contact with a shaft (S, gray); bar: 0.5 μm. Middle right: synapse in contact with both leaflets emerging from a shaft and the shaft itself; bar: 0.5 μm. Bottom right: synapse in contact with leaflets emerging from cell body (soma). Bar: 1 μm.

Calcium activity in leaflets

2-photon calcium imaging revealed very rapid, localized calcium micro-events, often triggered by neuronal activity.

These signals depend on IP₃R1 receptors in the i-ER and can propagate from one leaflet to another via gap junctions.

When they merge, these signals create broader calcium waves capable of synchronizing several neighboring synapses.

Figure 7. Leaflet domains host multiple synapses from independent circuits and display complex Ca2+ events that can integrate their ongoing activities in space and time. (B) Left: single-plane time-series capturing a representative multi-originated Ca2+ event in “Leaflets” (pseudocolor Ca2+ intensity scale, see “Two-photon 3D+t imaging data analysis” in STAR Methods). “Mitochondria” regions (azure pseudocolor) display an independent event. Right: oriented graph representation of the evolution of the event in “Leaflets,” visualizing spatial and time aspects, directionality, and intensity. (i), (ii), and (iii): timings of the images on the left. Arrowheads in (i) and (ii) identify distinct origination sites, and in (iii) their merging into a larger, long-lasting event. Bar: 1 μm. (C) Left: time-series as in (B), here capturing a Ca2+ event in “Leaflets” with three distinct originations (arrowheads). Two of them appear simultaneously in (i), the third, delayed, at another location in (ii), while in (iii) they all merge into a larger, long-lasting, high-intensity Ca2+ elevation. Noteworthy, the event expands around “Mitochondria” regions without touching them. Bar: 1 μm. Right: oriented graph representation of the Ca2+ event’s dynamics as in (B).

Conclusion

The results show that astrocytes are not mere support cells, but true biological computation units, where each leaflet acts as a functional “pixel” in a mosaic capable of interpreting and integrating multiple neuronal signals through the language of calcium.
This new astrocyte-oriented approach could pave the way for further studies exploring other brain regions to determine whether similar mechanisms exist elsewhere in the nervous system.

Read the scientific article here!

Benoit L, Hristovska I, Liaudet N, Jouneau PH, Fertin A, de Ceglia R, Litvin DG, Di Castro MA, Jevtic M, Zalachoras I, Kikuchi T, Telley L, Bergami M, Usson Y, Hisatsune C, Mikoshiba K, Pernet-Gallay K, Volterra A. Astrocytes functionally integrate multiple synapses via specialized leaflet domains. Cell. 2025 Sep 24:S0092-8674(25)01028-1. doi: 10.1016/j.cell.2025.08.036. Epub ahead of print. PMID: 40997814.

Last week, France-BioImaging participated in the Global BioImaging Exchange of Experience 2025. This year’s edition brought together scientists, facility managers, and infrastructure leaders from the international imaging community to explore “Imaging in 2035 – Sustaining Infrastructure Ecosystems & Advanced Technologies.”

Co-organized by BioImaging North America and Canada BioImaging, the event fostered rich exchanges among imaging infrastructure stakeholders on how to ensure the long-term sustainability of our global imaging ecosystem. France-BioImaging was represented by Caroline Thiriet and Jean Salamero who, as Mission Officer for Inter-Infrastructures Relationships at France-BioImaging and member of the Global BioImaging Working Group on Impact, moderated the session dedicated to “Micro-to-Macro: Measuring the Hidden Impacts of Imaging Scientists & Networks.” The session gathered a vibrant panel of experts — Susan Warner, Nick Souter, Johanna Bischof, Caron Jacobs, Leonel Malacrida, and Michelle Itano — who discussed how to communicate impact, reduce research’s carbon footprint, and recognize the essential contributions of imaging scientists worldwide.

The event also featured an inspiring keynote by Teng-Leong Chew (HHMI Janelia Research Campus) on “Microscopy Dissemination and Adoption Across the Globe.”

A big thank you to our global partners for an inspiring week of exchange and vision-building for the future of bioimaging!

This new edition, dedicated to the complete imaging workflow, from sample preparation to image analysis, will take place from November 5 to 7, 2025, in Versailles.

Program

The program includes numerous conferences and practical workshops on major topics:

  • Fluorescence lifetime imaging (FLIM/multi-color)
  • Live imaging – Biosensors
  • 2D and 3D electron imaging
  • Label-free imaging
  • Supervised learning, AI, and image analysis
  • Chemical imaging

Find the detailed program below:

Programme 14e Journee microscopistes INRAEDownload

This event is open to all! Whether you are a researcher, engineer, or technician, don’t miss this opportunity to network with other members of the community.

General information

When? November 5-7, 2025

Where? Centre INRAE Versaille-Saclay

The registration is free but mandatory – Deadline October 24

Find more information and registration link here: https://rmui-2025.journees.inrae.fr/

MIDOG is a challenge organized on the occasion of the MICCAI conference, dedicated to medical image computing and computer-assisted intervention. This bioinformatics competition focused on mitotic figures, which are a key biomarker in tumor grading. The variability of clinical samples makes the detection and classification of mitotic figures difficult for current AI models. The aim of MIDOG 2025 was to address this problem by testing algorithms in atypical conditions.

With their solutions, Thomas Walter’s team won:

  • 2nd place in Task 1 focused on mitotic figures detection. They designed a robust and efficient YOLOv12 one-stage model, combined with a streamlined preprocessing pipeline. The approach enables fast detection of both mitotic figures and hard negatives, and benefits from a precise data augmentation process integrating multi-target Macenko stain normalization.
  • 1st place in Task 2 dedicated to atypical mitotic figure classification. They leveraged the DINOV3-H+ foundation model, originally pretrained on natural images; and fine-tuned it with LoRA, requiring only ~1.3M trainable parameters. To tailor the model to histopathology, they incorporated extensive domain-specific data augmentations and implemented a domain-aware focal loss, allowing them to better handle both class and domain imbalance during training.

You can read the preprint of their solutions here:

The Rhône-Alpes node, co-led by Xavier Jaurand and Olivier Destaing, unites the imaging communities of Lyon and Grenoble. With platforms such as ISDV and LyMIC, and several R&D teams, the node covers a broad range of applications from metabolic imaging to spatial transcriptomics. Recent years have seen major scientific publications and significant technical upgrades. Looking ahead, the node aims to expand training, foster joint technology developments, and will proudly host the infrastructure Annual Meeting in 2027, while deepening collaborations within Euro-BioImaging.

Could you introduce yourself and your role within the Rhône-Alpes node?

The Rhône-Alpes node brings together the large imaging communities of Lyon and Grenoble. I’m Xavier Jaurand and I’m co-leading the node with Olivier Destaing. This  way of co-sharing responsibility is at the heart of our project in order to have synergy of both science-technology and Grenoble-Lyon communities. This organization has been transposed at the different levels of our node, through duo of peoples from Lyon and Grenoble invested in the multiple working group of FBI. 

[Xavier Jaurand]: I’m the technical director of the “Centre Technologique des Microstructures (CTµ)”, a microscopy core facility of University Claude Bernard Lyon1, where I have been working for 20 years now, mainly in the field of electron microscopy (SEM and TEM).

[Olivier Destaing]: I am DR2-CNRS and co-leader of a research team on the cell biology of invasion processes and their associated signaling regulations. Implicated in imaging development and optogenetics since many years, I am also the co-scientific leader of the imaging platform MicroCell of the Institute for advanced Biosciences (IAB).

Having organization with shared responsibilities is always a challenge and take time, but present the advantages of being potentially highly robust and well accepted by large communities.

Which platforms and R&D teams compose your node?

There are 2 main platforms on the nodes (ISDV and LyMIC):

  • For the Grenoble part, the ISDV (Imagerie Science du Vivant) network is composed by 7 platforms (LBFA, Liphy, PIC-GIN, ME-GIN, MicroCell-IAB, MuLife-CEA, TIMC, M4D-IBS)
  • For the Lyon part, the associated facility is LyMIC (Lyon Multiscale Imaging Center) which is the federation of 3 imaging platforms: PLATIM (south of Lyon), CIQLE (east of Lyon) and CTµ (north of Lyon).

There are both biology and Physics R&D teams:

  • ILM UMR5306 Team Dehoux – Unique expertise in Brillouin microscopy for imaging cells and tissues at various scales.
  • RDP UMR5667 Team Ingram – Measuring cell hydrostatic pressure and cell wall properties is challenging but of critical importance in the field of plant biology.
  • IGFL UMR5242 Team Enriquez/Ghavi-Helm – The Spatial-Cell-ID EQUIPEX facility enhance the spatial resolution of MERFISH by pinpointing transcripts of specific genes (ranging from a few to thousands) in situ, achieving cellular and subcellular precision over time.
  • IAB UMR5309 Team Destaing – the lab is focused on coupling optogenetics, biosensors and metabolism imaging through FLIM imaging.
  • Liphy UMR5588 Team Dupont – The OPTIMA team brings together expertise in imaging (optical, acoustic, X-ray) to develop new instruments, explore the physics of wave-matter interactions, and address biological and biomedical challenges where its scientific and technical know-how provides significant added value.
  • Liphy UMR5588 Team Débarre – The MC2 team conducts interdisciplinary research at the crossroads of mechanics, physics, and life sciences to investigate, across scales, the dynamics and interactions of biological or bioinspired systems in complex environments.
  • GIN U1216 Team Pernet-Gallay – The electronic microscopy facility is located at the Grenoble Institute for Neuroscience (GIN, INSERM U1216, UGA) and proposes classic epoxy resin embedding for morphological analysis, as well as the Tokuyasu protocol for immunogold labeling on cryosections.

Which are the main application domains of your node?

  • Metabolic imaging, cell signaling and dynamics manipulation
  • Biomechanics: from single molecule to tissue, from animals to plants 
  • Spatial cell transcriptomics
  • 3D multiscale imaging through development in adaptive optics or original analysis of deep FIB-SEM acquisition
  • 3D and high content image processing

Can you share a scientific or technical success achieved within your node?

Over the past two years, our node’s scientific impact is reflected by the co-authorship of our core facility staff in several high-profile publications, covering topics from immunology to molecular imaging and dermatology:

  • Functional diversity of NLRP3 gain-of-function mutants associated with CAPS autoinflammation (2024) J Exp Med. doi.org/10.1084/jem.20231200
  • Sperm motility in mice with Oligo-astheno-teratozoospermia restored by in vivo injection and electroporation of naked mRNA (2024) eLife. doi.org/10.7554/eLife.94514.1
  • Nanoassemblies of Chitosan-Based Polyelectrolyte Complexes as Nucleic Acid Delivery Systems (2024) Biomacromolecules. doi.org/10.1021/acs.biomac.4c00054
  • RNAP II antagonizes mitotic chromatin folding and chromosome segregation by condensin (2024) Cell Reports. doi.org/10.1016/j.celrep.2024.113901
  • Dermal stiffness governs the topography of the epidermis and the underlying basement membrane in young and old human skin (2024) Aging Cell. doi.org/10.1111/acel.14096
  • Plasmacytoid dendritic cell sensing of hepatitis E virus is shaped by both viral and host factors (2024) Life Sci Alliance. doi.org/10.26508/lsa.202503256

On the technical side, our node has recently strengthened its infrastructure and expertise through major investments and upgrades, ranging from state-of-the-art microscopy systems to reinforced image analysis capacities and dedicated staffing:

  • Purchase and deployement of new and unique material at Lyon: AFM coupled to an inverted epifluorescence microscope, equipped with a motorized and piezoelectric stage (Hybrid Stage) that enables the acquisition of measurements on samples extended in the plane (e.g., tissue sections) or in height (e.g., whole tissues/organs).
  • Upgrade of confocal microscopy ressources: We replaced our aging Leica SP5X with a Leica Stellaris 5, featuring TauSense temporal dimension imaging and a resonnant scanner. Funding was secured through a strategic partnership between the university, region, and internal investment. A new spinning disk system was integrated to a FastFLIM-TIRF module in order to provide new metabolic imaging possibilities in 4-5D.
  • Enhance STED FLIM capabilities: We equipped our Abberior STED system with a FLIM module, delivering super-resolved temporal imaging with < 40 nm spatial resolution while preserving excellent time and signal fidelity. This integration enables dynamic, quantitative imaging of molecular interactions and environments.
  • Strengthen image-analysis infrastructure: We deployed three dedicated workstations equipped with AI-assisted tools such as for segmentation and analysis. These platforms enable advanced processing, rapid 3D visualization, and robust quantification, empowering both academic and translational research workflows.
  • Launch of a permanent image-analysis engineer role: In 2025, we transitioned from temporary contracts to a permanent research engineer position specialized in image analysis. This ensures stable expertise in AI-driven segmentation, 3D visualization, and quantitative imaging. The engineer also leads user training and engages actively in national (FBI) and European (NEUBIAS) working groups.

What are your perspectives following your node’s integration into France-BioImaging?

Following our integration into France-BioImaging, we aim to foster stronger connections between AURA’s users (academic users and private companies) and the opportunities offered by the infrastructure. We also seek to highlight and transfer original technologies (Brillouin imaging and quantitative RICM), improve access to advanced data management and image analysis to our user, and democrate these cultures to the numerous biology laboratories of Rhône-Alpes. We also plan to contribute to Euro-BioImaging initiatives, all while enhancing our international visibility.

To achieve these goals, our node is committed to participating in expert working groups (RTmfm network and FBI), deploying nationally shared training modules and engaging in joint technology developments in 3D tissue imaging, sample clearing, and multimodal microscopy. We will also continue to strengthen data and AI workflows, and we are proud to be preparing the organization of the France-BioImaging Annual Meeting in 2027.

Your node has recently joined Euro-BioImaging, what added value do you think you bring to the European community?

As part of a Euro-BioImaging fellowship, the MicroCell platform at IAB Grenoble hosted Sarah Vorsselmans and Susana Rocha (KU Leuven, Belgium). Together, we worked on the development of innovative FRET-based multiplexing molecular tension sensors, strengthening transnational expertise in molecular imaging

In April 2025, the LYMIC platform welcomed a job shadowing candidate from Germany for ten days. This exchange provided an opportunity to share practices on biological sample preparation for electron microscopy, as well as image analysis, data storage, and quality management.

The Plant Imaging Expert Group of Euro-BioImaging is organizing a new webinar to introduce the DREAM project, Wednesday, September 24, at 13:00!

What is the DREAM project?

DREAM stands for “Dynamic Regulation of Photosynthesis in Light-Acclimated Organisms”. This research initiative aims to develop a new generation of instrumentation and data acquisition protocols to better evaluate the dynamics of photosynthesis. A better understanding of this mechanism in plants could open promising pathways toward sustainable agriculture that meets global challenges.

A webinar with France-BioImaging members

Members of France-BioImaging and DREAM, Ludovic Jullien, Ian Coghill – from the Chemistry Department of ENS (Sorbonne University/CNRS) – and Aliénor Lahlou (Chemistry Department ex-member, now PhD research at Sony CSL) will present the overall objectives of the project as well as its latest outcomes.

How to join?

Meeting link here.

More info? https://www.eurobioimaging.eu/events/plant-imaging-expert-group-meeting-dynamic-regulation-of-photosynthesis-in-light-acclimated-organisms/

The France-BioImaging Preclinical Microscopy working group is organizing its next webinar on Thursday, September 25th from 14:00 to 16:00.

This session, open to all, will focus on advanced imaging solution with two keynotes:

  • Label-free 3D imaging of thick samples by Kaer Labs – 14:00
  • Quantitative blood vessel photoacousticmicroscopy coupled with ultrasonicmicroscopy by Bastien Arnal (LiPhy, Université Grenoble Alpes, CNRS) – 14:55

This webinar will conclude with an open discussion!

To join us, click here!

Meeting ID: 339 429 931 973 3
Passcode: PY6E2v4A

The 2nd edition of the Single Cell Conference of Nantes focused on “Deciphering single cell interactions in health and disease” will take place on October 7 and 8, 2025.

This event aims to highlight the use of single cell analysis technologies applied to the study of cellular mechanisms. Many international and local speakers will present the latest methods and applications in single-cell analysis.

In addition, participants will have the opportunity to present their research project after the submission and selection of an abstract.

A bioinformatics workshop dedicated to spatial data analysis will also be held on the afternoon of the second day (14:00-17:00).

General information

The participant have until September 19, 2025 at 17:00 to submit their abstract and/or apply for the bioinformatics workshop.

The registration is free for standard academic registration.
A fee of 50€ is asked for Senior Academic Registration (CR, DR, MCU, PU, Lecturer, goup leader…) and of 100€ for Industry Registration.

Find the program and the registration link here: https://nantescell.sciencesconf.org/

This autumn, two France-BioImaging microscopy platforms are inviting the public to dive into the fascinating world of microscopy! Discover their upcoming events.

Montpellier Ressources Imagerie platform

The Montpellier Ressources Imagerie platform will present a photography exhibition of their microscopy images, “Life is Beautiful”, showcased at several events. This project was awarded the Euro-BioImaging EVOLVE call.

IMAG’IC

IMAG’IC, the Institut Cochin imaging platform, will take part in the CNRS “Visites Insolites”, giving the public a rare chance to explore usually inaccessible scientific spaces and experience science in unexpected ways!

  • Applications are mandatory to join this visit and are open until September, 17th. Apply here
  • When? October, 8th – Starting from 13:30

These events offer the public a chance to discover the fascinating world of science, and microscopy in particular, through accessible and engaging formats, from art to playful experiences.

A research project* at the IBDM (Marseille Developmental Biology Institute, CNRS – AMU), led by Clément Rodier, has recently challenged long-standing scientific hypotheses about how muscles elongate during development, thanks to advanced microscopy. Let’s take a closer look!

Sarcomeres, the “bricks” of muscles

Striated muscles are made up of muscle fibers, themselves composed of myofibrils, chains of thousands of contractile “bricks” called sarcomeres. In mammals, a sarcomere measures between 2 and 3 micrometers.

As an organism grows, its muscles must expand to keep pace with skeletal development. Yet sarcomeres maintain roughly the same size. For decades, the prevailing hypothesis held that new bricks, sarcomeres, were added exclusively at the ends of myofibril chains. However, it had never been directly observed. Clément Rodier’s goal was to visualize, using both light and electron microscopy**, how new sarcomeres are inserted during muscle growth, with the fly Drosophila as a model system.

A scientific hypothesis challenged

The research team analyzed Drosophila flight muscles between 32 and 40 hours after puparium formation, the developmental stage following the larval phase. This model has a key advantage: its growth is extremely fast (around 100 new sarcomeres are added in just 4 hours!) making the mechanism easier to capture.

Contrary to the initial hypothesis, microscopy images showed that sarcomere insertion was not restricted to the ends of the myofibrillar chain. Each brick is capped by terminal structures called Z-discs, which should have shown changes if new sarcomeres were only added there.

(B) Schematic of a Drosophila hemithorax at pupal stages with the six dorsal longitudinal flight muscles (DLMs) in magenta and the tendon cell epithelium in green. DLM4 is highlighted and was used for quantifications in (E). The stable connection of the flight muscles to the tendon cell extensions (green lines) during the growth phase from 32 to 40 hours after puparium formation (APF). h, hours. (C and D) Confocal images of pupae of the indicated stages displaying the six flight muscles stained for actin (phalloidin in red) and Shot (anti-Shortstop in gray, also labeling the tendon extensions) in (C). High magnifications displaying the myofibrils stained for actin (red) and myosin [anti–Mhc (myosin heavy chain) in blue] in (D). Scale bars, 100 μm in (C) and 5 μm in (D). Note the marked muscle length increases after 32 hours APF. 

(B and C) About 34 hours APF, a pupa expressing Sls-GFP with a focus on the anterior flight muscle end. Stills from movie S1 are shown (B), and a kymograph of a selected region is shown (C). The myofibril ends, marked with yellow arrowheads, move to the left, while muscle fiber length increases and thus moves away from the reference point marked with the orange arrowhead. No obvious sarcomere addition is seen at the ends.

So how do muscles really grow?

To probe this mechanism further, the team developed a computational tool capable of analyzing the length of thousands of sarcomeres and identifying those with abnormal size.
Using this tool combined with high-resolution microscopy techniques (sush as in vivo bi-photon imaging), the researchers observed that some sarcomeres gradually elongated and then split into two daughter sarcomeres of normal length. The essential proteins needed for proper sarcomere function were also restored.

Unlike the long-accepted end hypothesis, this division mechanism allows new sarcomeres to be inserted at multiple points along the myofibril.

Fig. 7. Sarcomere division model. Working model of the tension-induced sarcomere division in Drosophila flight muscle sarcomeres. The growth of the skeleton, marked by integrin-based attachments, induces high tension, which triggers the division of the highlighted middle sarcomere. Thus, the sarcomere number increases from three to four. For details, see Discussion.

Does this mechanism also occur in mammals?

The researchers next turned to 3D electron microscopy and FRAP to test whether this mechanism also applied to other muscle types, namely Drosophila larval muscles, which are similar to mammalian skeletal muscles.

These imaging techniques revealed a zipper-like division process of sarcomeres during larval development. Further analyses confirmed the recruitment of new proteins that reestablish proper function in the daughter sarcomeres.

Looking ahead

Thanks to the combination of light and electron microscopy, both realized on France-BioImaging’s core facilities*, the team was able to put a long-standing hypothesis to the test… and overturn it! This work sheds new light on developmental mechanisms in insects, and possibly in mammals, including humans. Better understanding how muscles grow at the microscopic level could one day pave the way for novel therapies to fight muscle degenerative diseases.

* Clement Rodier et al., Muscle growth by sarcomere divisions. Sci. Adv.11, eadw9445 (2025). DOI:10.1126/sciadv.adw9445

** Electronic microscopy (3D EM) was performed on a PICsL core facility and advanced photonic microscopy (FRAP imaging, in vivo bi-photon imaging) on IBDM core facility.