Pierre Mahou

École Polytechnique · Laboratoire d'Optique et Biosciences (LOB)

Clathrin-mediated endocytosis is the major route of entry of cargos into cells and thus underpins many physiological processes. During endocytosis, an area of flat membrane is remodeled by proteins to create a spherical vesicle against intracellular forces. The protein machinery which mediates this membrane bending in plants is unknown. However, it...

Solar ultraviolet longwave UVA1 exposure of human skin has short-term consequences at cellular and molecular level, leading at long-term to photoaging. Following exposure, reactive oxygen species (ROS) are generated, inducing oxidative stress that might impair cellular metabolic activity. However, the dynamic of UVA1 impact on cellular metabolism r...

Nondestructive and noninvasive investigation techniques are highly sought-after to establish the degradation state of historical parchments, which is up to now assessed by thermal techniques that are invasive and destructive. We show that advanced nonlinear optical (NLO) microscopy enables quantitative in situ mapping of parchment degradation at th...

Methylselenol (MeSeH) is a major cytotoxic metabolite of selenium, causing apoptosis in cancer cells through mechanisms that remain to be fully established. Previously, we demonstrated that, in Saccharomyces cerevisiae, MeSeH toxicity was mediated by its metabolization into selenomethionine by O-acetylhomoserine (OAH)-sulfhydrylase, an enzyme that...

Clathrin-mediated endocytosis in plants is an essential process but the underlying mechanisms are poorly understood, not least because of the extreme intracellular turgor pressure acting against the formation of endocytic vesicles. In contrast to other models, plant endocytosis is independent of actin, indicating a mechanistically distinct solution...

Neural stem cell (NSC) populations persist in the adult vertebrate brain over a lifetime, and their homeostasis is controlled at the population level through unknown mechanisms. Here, we combine dynamic imaging of entire NSC populations in their in vivo niche over several weeks with pharmacological manipulations, mathematical modeling, and spatial...

2D cell cultures are commonly used to rapidly evaluate the therapeutic potential of various treatments on living cells. However, the effects of the extracellular matrix (ECM) including the 3D arrangement of cells and the complex physiology of native environment are missing, which makes these models far from in vivo conditions. 3D cell models have e...

Improving the imaging speed of multiphoton microscopy is an active research field. Among recent strategies, light-sheet illumination holds distinctive advantages for achieving fast imaging in vivo. However, photoperturbation in multiphoton light-sheet microscopy remains poorly investigated. We show here that the heart beat rate of zebrafish embryos...

Neural stem cell (NSC) populations persist in the adult vertebrate brain over a life time, and their homeostasis is controlled at the population level. The nature and properties of these coordination mechanisms remain unknown. Here we combine dynamic imaging of entire NSC populations in their in vivo niche over weeks, pharmacological manipulations,...

Improving the imaging speed of multiphoton microscopy is an active research field. Among recent strategies, light-sheet illumination holds distinctive advantages for achieving fast imaging in vivo. However, photoperturbation in multiphoton light-sheet microscopy remains poorly investigated. We show here that the heart beat rate of zebrafish embryos...

Two-photon light-sheet microscopy (2P-SPIM) provides a unique combination of advantages for fast and deep fluorescence imaging in live tissues. Detecting coherent signals such as second-harmonic generation (SHG) in 2P-SPIM in addition to fluorescence would open further imaging opportunities. However, light-sheet microscopy involves an orthogonal co...

We report on recent advances in multiphoton light-sheet microscopy to perform fast multimodal imaging combining fluorescence with second-harmonic generation and to mitigate photodamage during in vivo imaging of embryos.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

Body-axis elongation constitutes a key step in animal development, laying out the final form of the entire animal. It relies on the interplay between intrinsic forces generated by molecular motors1–3, extrinsic forces exerted by adjacent cells4–7 and mechanical resistance forces due to tissue elasticity or friction8–10. Understanding how mechanical...

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

Affiliation 4 incorrectly read ‘University of the Basque Country (Ikerbasque), University of the Basque Country and Donostia International Physics Center, San Sebastian 20018, Spain.’ Also, the affiliations of Ignacio Arganda-Carreras with ‘IKERBASQUE, Basque Foundation for Science, Bilbao, 48013, Spain’ and ‘Donostia International Physics Center (...

Large-scale microscopy approaches are transforming brain imaging, but currently lack efficient multicolor contrast modalities. We introduce chromatic multiphoton serial (ChroMS) microscopy, a method integrating one‐shot multicolor multiphoton excitation through wavelength mixing and serial block-face image acquisition. This approach provides organ-...

Large-scale microscopy techniques are transforming brain imaging but lack efficient multi-contrast modalities. Our work combines two-photon wavelength-mixing and serial tomography microscopy to overcome this limitation, and demonstrates the potential of this approach in various contexts.

Using the haloarchaeon Haloferax volcanii as a model, we developed nascent DNA labeling and the functional GFP-labeled single-stranded binding protein RPA2 as novel tools to gain new insight into DNA replication and repair in live haloarchaeal cells. Our quantitative fluorescence microscopy data revealed that RPA2 forms distinct replication structu...

Living crystallization-driven self-assembly (CDSA) is a seeded growth method for crystallizable block copolymers (BCPs) and related amphiphiles in solution and has recently emerged as a highly promising and versatile route to uniform core–shell nanoparticles (micelles) with control of dimensions and architecture. However, the factors that influence...

Multiphoton microscopy combined with genetically encoded fluorescent indicators is a central tool in biology. Three-photon (3P) microscopy with excitation in the short-wavelength infrared (SWIR) water transparency bands at 1.3 and 1.7 µm opens up new opportunities for deep-tissue imaging. However, novel strategies are needed to enable in-depth mult...

Here, we report on efficient and simultaneous multicolor two-photon excitation of endogenous fluorophores with absorption spectra spanning the 750-1040nm range, using wavelength mixing.

We demonstrate dual-color three-photon imaging of red and green fluorescent proteins in neural tissue using a novel ultrafast laser design providing simultaneous excitation at 1300 and 1700 nm.

We demonstrate dual-color three-photon imaging of red and green fluorescent proteins in neural tissue using a novel MHz OPA design providing simultaneous excitation at 1300 and 1700 nm.

We present a novel ultrafast laser design providing simultaneous excitation in the two water-transparency windows at 1.3 and 1.7 µm, and we demonstrate its potentiality for efficient 3-photon microscopy of nervous tissues.

In multiphoton microscopy, the ongoing trend toward the use of excitation wavelengths spanning the entire near-infrared range calls for new standards in order to quantify and compare the performances of microscopes. This article describes a new method for characterizing the imaging properties of multiphoton microscopes over a broad range of excitat...

Two-photon imaging of endogenous fluorescence can provide physiological and metabolic information from intact tissues. However, simultaneous imaging of multiple intrinsic fluorophores, such as nicotinamide adenine dinucleotide(phosphate) (NAD(P)H), flavin adenine dinucleotide (FAD) and retinoids in living systems is generally hampered by sequential...

Nature Communications 7 : Article number: 12563 10.1038/ncomms12563 ( 2016 ); Published: 19 September 2016 ; Updated 11 May 2017 In the original version of Supplementary Data 1 associated with this Article, the FastPeakFind.m function was incorrectly attributed to the authors in the function’s header.

The aggregation promoter heparin is commonly used to study the aggregation kinetics and biophysical properties of protein amyloids. However, the underlying mechanism for amyloid promotion by heparin remains poorly understood. In the case of the neuropeptide β-endorphin that can reversibly adopt a functional amyloid form in nature, aggregation in th...

Reconstructing neural circuits and cell lineage raises the challenge of imaging large volumes of tissue with high contrast, specificity and resolution. Our work aims at combining Brainbow labeling and large-volume microscopy to reach this goal.

We propose an innovative OPCPA source for deep-tissue multiphoton microscopy providing µJ pulses at 1700 nm. We demonstrate its performances for in-depth 3-photon imaging of mouse brain tissue and compare them with 2-photon microscopy.

α-synuclein (αS) is an intrinsically disordered protein whose fibrillar aggregates are the major constituents of Lewy bodies in Parkinson’s disease. Although the specific function of αS is still unclear, a general consensus is forming that it has a key role in regulating the process of neurotransmitter release, which is associated with the mediatio...

Matlab scripts for the analysis of super-resolution images.

Instructions for obtaining rapidSTORMM

Supplementary Figures 1-11

Scientific Reports 6 : Article number: 29863; 10.1038/srep29863 published online: 20 July 2016 ; updated: 25 August 2016 This Article contains typographical errors.

Second-harmonic generation (SHG) is the most specific label-free indicator of collagen accumulation in widespread pathologies such as fibrosis, and SHG-based measurements hold important potential for biomedical analyses. However, efficient collagen SHG scoring in histological slides is hampered by the limited depth-of-field of usual nonlinear micro...

New strategies for visualizing self-assembly processes at the nanoscale give deep insights into the molecular origins of disease. An example is the self-assembly of misfolded proteins into amyloid fibrils, which is related to a range of neurodegenerative disorders, such as Parkinson's and Alzheimer's diseases. Here, we probe the links between the m...

Protein structures which form fibrils have recently been shown to absorb light at energies in the near UV range and to exhibit a structure-specific fluorescence in the visible range even in the absence of aromatic amino acids. However, the molecular origin of this phenomenon has so far remained elusive. Here, we combine ab initio molecular dynamics...