Publications

2026

• Photo-switching Quantum Yield of Reversibly Switchable Fluorescent Proteins depends on Wavelength and Temperature
  
  • Fu Xingjie
  • Uriarte Lucas Martinez
  • Mittelheisser Cédric
  • Devos O.
  • Laurent Guillaume
  • Sliwa Michel
  , 2026. Reversibly switchable fluorescent proteins (RSFPs) enable super-resolved bio-imaging by leveraging the photo-switching between their On-and Off-forms. The photoswitching quantum yield (φ) is the key parameter that characterizes the switching efficiency of RSFPs, yet reported values vary widely. Although, the quantum yield of molecular organic photo-switches is known to depend on both temperature and excitation wavelength, these dependencies have often been overlooked in studies of RSFPs. To study the modulation of φ, the wild type rsEGFP2 as well as two of its variants were selected. The wild type rsEGFP2 is a representative RSFP that has been reported multiple times in the literature of nanoscopy, and exibits up to four-fold variation in the reported values of φ. We measured the dependence of values on temperature (from 10 to 35°C) and on irradiation wavelength (408 and 480 nm) across variants, revealing evidence of distinct cis-trans excited state isomerization pathways. These results suggest that temperature-and wavelength-dependence are general properties of RSFPs and may offer new insights into their photo-switching mechanisms, enabling the development of novel temperature-and color-modulated imaging strategies.
• Non-invasive quantitative investigation of varnish stratigraphy in historical artifacts using line-field confocal OCT
  
  • Galante Giulia
  • Vilbert Maëlle
  • Desvois Laetitia
  • Le Corre Diane
  • Archambault Lou
  • Robinet Laurianne
  • Saumagne Nicolas
  • Schanne-Klein Marie-Claire
  • Latour Gaël
  npj Heritage Science, Springer Nature, 2026, 14, pp.193. Optical Coherence Tomography (OCT) is a powerful non-destructive and non-invasive 3D imaging technique for cultural heritage artifacts. It provides morphological information, such as in-depth layer mapping and particle presence. Line-field Confocal OCT (LC-OCT) combines OCT with confocal microscopy to achieve improved spatial resolution (~1 µm) and fast imaging, while maintaining a similar penetration depth to standard OCT. LC-OCT combined with automated data processing is used to map varnish layers and characterize their removal during conservation treatments. It is applied to a 17th century painting, to document previous restorations, and to a 17th century violin by the renowned Italian violin-maker Nicolo Amati, to assess the presence of its unique original varnish and optimize the conservation process for the selective removal of the overlying non-original varnish. This demonstrates the effectiveness of LC-OCT as a new technique for the quantitative characterization and conservation guidance of varnished cultural heritage artifacts. (10.1038/s40494-026-02460-4)
  DOI : 10.1038/s40494-026-02460-4
• Revealing photochemical processes using multiple-timescale multiple-probing visible transient absorption spectroscopy with two independent femtosecond amplifiers
  
  • Balanikas Evangelos
  • Solinas Xavier
  • Antonucci Laura
  • Bonvalet A.
  • Prouteau Matthieu
  • Sanchez Iris
  • Colasson Benoit
  • Abe Jiro
  • Changenet-Barret, Pascale
  • Sliwa Michel
  • Joffre Manuel
  , 2026. Deciphering complex photochemical mechanisms requires multiple-timescale methods capable of resolving dynamics from femtoseconds to milliseconds. We demonstrate that Arbitrary Detuning Asynchronous Optical Sampling (ADASOPS) can be combined with the technique known as multiple probing. By integrating a 1-kHz Titanium:Sapphire and a 125-kHz Ytterbium femtosecond amplifier, we control the time delay on a shot-by-shot basis and perform fast scanning over 8 decades with 500-fs resolution. We validate this method by resolving intersystem crossing in copper phenanthroline complexes, capturing dynamics from 700 fs to 40 ns, and reveal photomechanisms in a fast photochromic molecule, including picosecond bond dissociation and microsecond thermal recovery. Requiring no laser modifications, our approach should accelerate the widespread adoption of multiple-timescale multiple-probing spectroscopy.
• Multimodal AFM-IR nanospectroscopy and non-linear optical microscopy for detecting collagen matrix alterations
  
  • Mathurin Jérémie
  • Latour Gaël
  • Mosser Gervaise
  • Dazzi Alexandre
  • Schanne-Klein Marie-Claire
  • Deniset-Besseau Ariane
  Analyst, Royal Society of Chemistry, 2026, 151, pp.1881 - 1888. Correlative photothermal infrared nanospectroscopy (AFM-IR) and non linear optical microscopy analyses reveal that the emergence of a 1730 cm -1 IR band in collagen arises from local, thermally induced esterification. This band serves as a marker of irreversible molecular alteration, associated with structural destabilisation and chemical changes within the collagen matrix. (10.1039/d5an01298h)
  DOI : 10.1039/d5an01298h
• Structural and chemical characterization of slough in chronic wounds
  
  • Nurlybayeva Assem
  • Tang Ellie
  • Moguelet Philippe
  • Schanne-Klein Marie-Claire
  • Deniset-Besseau Ariane
  • Colboc Hester
  Vascular Diseases, Elsevier, 2026, 51 (1), pp.29. Correlative photothermal IR nanospectroscopy (AFM-IR) and non-linear optical microscopy analyses reveal that the emergence of a 1730 cm −1 band in collagen arises from local, thermally induced chemical alteration. (10.1016/j.vasdi.2026.01.100)
  DOI : 10.1016/j.vasdi.2026.01.100
• Archaeal G-quadruplexes: a novel model for understanding unusual DNA/RNA structures across the tree of life
  
  • Aktary Zackie
  • Sorg Kate
  • Cucchiarini Anne
  • Vesco Guglielmo
  • Noury Dorian
  • Zhang Rongxin
  • Jourdain Thomas
  • Verga Daniela
  • Mahou Pierre
  • Olivier Nicolas
  • Bohálová Natália
  • Porubiaková Otília
  • Brázda Václav
  • Bouvier Marie
  • Kwapisz Marta
  • Clouet-D’orval Béatrice
  • Allers Thorsten
  • Lestini Roxane
  • Mergny Jean-Louis
  • Guittat Lionel
  Nucleic Acids Research, Oxford University Press, 2026, 54 (4). Archaea, a domain of microorganisms found in diverse environments, including the human microbiome, represent the closest known prokaryotic relatives of eukaryotes. This phylogenetic proximity positions them as a relevant model for investigating the evolutionary origins of nucleic acid secondary structures such as G-quadruplexes (G4s) which play regulatory roles in transcription and replication. Although G4s have been extensively studied in eukaryotes, their presence and function in archaea remain poorly characterized. In this study, a genome-wide analysis of the halophilic archaeon Haloferax volcanii identified over 5800 potential G4-forming sequences. Biophysical validation confirmed that many of these sequences adopt stable G4 conformations in vitro. Using G4-specific detection tools and super-resolution microscopy, G4 structures were visualized in vivo in both DNA and RNA across multiple growth phases. Comparable findings were observed in the thermophilic archaeon Thermococcus barophilus. Functional analysis using helicase-deficient H. volcanii strains further identified candidate enzymes involved in G4 resolution. These results establish H. volcanii as a tractable archaeal model for G4 biology. (10.1093/nar/gkag067)
  DOI : 10.1093/nar/gkag067
• Selective Disruption of Plasmodium falciparum mitochondrial DNA via G-Quadruplex-Binding Ligand RHPS4 Provides a Novel Antimalarial Strategy
  
  • Salim Mariam
  • Paloque Lucie
  • Reyser Thibaud
  • Nardella Flore
  • Augereau Jean-Michel
  • Luo Yu
  • Britton Sébastien
  • Mergny Jean-Louis
  • Gervais Virginie
  • Benoit-Vical Françoise
  • Gomez Dennis
  , 2026. ABSTRACT Malaria caused by Plasmodium falciparum remains a major health threat, killing over 600,000 people annually. The spread of resistance to all major antimalarials, including artemisinins, highlights the urgent need for new drugs with distinct mechanisms of action. Here we show that the G-quadruplex ligand RHPS4, an acridine derivative, displays strong antiplasmodial activity against both drug-sensitive and -resistant P. falciparum strains and clinical isolates. RHPS4 primarily targets the trophozoite stage and induces major mitochondrial alterations, including reduction of mitochondrial DNA (mtDNA) and transcriptional dysfunctions. Bioinformatic analyses identified at least eight putative G4-forming sequences within the parasite’s mtDNA. Biophysical studies confirmed G4 folding of at least one sequence and its interaction with RHPS4. These findings indicate that RHPS4 disrupts P. falciparum mitochondrial metabolism through G4 stabilization, leading to parasite death, and establish mtDNA G4 structures as novel therapeutic targets for antimalarial development. (10.64898/2026.01.07.698092)
  DOI : 10.64898/2026.01.07.698092
• Pentanucleotide guanine-rich WGGGW repeats, including CANVAS AGGGA repeats, form a variety of noncanonical structures
  
  • Wang Jiawei
  • Qiu Dehui
  • Zhou Jun
  • Mergny Jean-Louis
  • Alberti Patrizia
  Nucleic Acids Research, Oxford University Press, 2026, 54 (3). Abstract Short tandem repeats (STRs) are an important component of the human genome as they contribute to genetic diversity and can influence gene expression and disease susceptibility. STRs are important in the context of CANVAS (Cerebellar Ataxia, Neuropathy, Vestibular Areflexia Syndrome) genetic disease as expansions of AGGGA repeats within the RFC1 gene are associated with the development of this neurodegenerative disorder. Interestingly, the RFC1 expanded motifs are pentanucleotides that differ from the nonpathogenic AGAAA pentanucleotide motif present in reference genomes. The molecular mechanisms underlying the pathogenicity of the mutated pentanucleotide expansion in CANVAS are still unknown. Several groups have shown that DNA and RNA containing AGGGA repeats fold into G-quadruplexes (G4s) under physiological K⁺ conditions. In this study, we reveal a more complex than expected behavior, in which DNA WGGGW motifs (where W is A or T) may adopt different G4 and non-G4 structures depending on sequence, repeat number and ionic conditions. These findings are relevant as they may help explain the genomic instability and pathogenicity specifically associated with AGGGA repeats among the WGGGW motifs. (10.1093/nar/gkag051)
  DOI : 10.1093/nar/gkag051
• Collagen microarchitecture from polarized light imaging: a biomechanics perspective
  
  • Kunz Miriam Bohlmann
  • Lee Po-Yi
  • Latour Gaël
  • Yang Bin
  • Schanne-Klein Marie-Claire
  • Kurokawa Kazuhiro
  • Sigal Ian A
  Journal of Biomedical Optics, Society of Photo-optical Instrumentation Engineers, 2026, 31 (1), pp.010902. Significance: Collagen, the main load-bearing component in tissue, is present in all animals and forms a variety of networks from the fibrils, fibers, bundles, and lamellae into which it self-assembles. The collagen microstructure is different among tissue types, and the different microstructures give rise to tissue-specific mechanical properties. Therefore, methods for visualizing collagen fibers and their orientation are essential for understanding the biomechanical properties of tissue. Aim: Our aim in this review is to provide the basis for understanding the methodology of polarized light imaging methods and how they can be used to characterize collagen microstructure. Approach: We begin with a description of collagen microstructure and its relationship to tissue biomechanics, a basic formalism of polarized light, and how collagen interacts with polarized light. We then describe polarized light microscopy and its various forms, particularly instant polarized light microscopy, then polarizationsensitive optical coherence tomography, and last, polarization-resolved secondharmonic generation microscopy. Results: We describe methods for imaging collagen microstructure with polarized light from in vivo methods to high-resolution volumetric imaging of tissue sections. Conclusions: We intend to help those interested in using polarized light to image and understand the relationship between collagen microstructure and biomechanics. (10.1117/1.jbo.31.1.010902)
  DOI : 10.1117/1.jbo.31.1.010902
• On the origins and variation of nucleotide skews of archaeal genomes
  
  • Paravel Adrien
  • Mottez Clémence
  • Puech Romain
  • Flament Didier
  • Becker Hubert F
  • Myllykallio Hannu
  Frontiers in Microbiology, Frontiers Media, 2026, 17, pp.1727296. We have used nucleotide skews as the proxy to understand the evolution of archaeal genomes. Our genome-wide studies using substantial datasets suggest that translational selection and the nature of the genetic code are universally conserved determinants of asymmetric guanine and cytosine distributions. We propose that in the case of the majority of bacterial chromosomes, mutational processes and/or DNA repair also result in the strand-specific nucleotide skews. This is in stark contrast to what we observe for archaeal chromosomes and plasmids, and reveals that archaea have a greatly reduced ability to create mutations and/or repair DNA damage in a strand-specific manner. We suggest that in the future, the described computational and statistical approach will help to understand the evolutionary dynamics of the archaeal chromosomes through the tree of life. (10.3389/fmicb.2026.1727296)
  DOI : 10.3389/fmicb.2026.1727296