Articles

The Nance-Horan syndrome protein NHS regulates cell migration persistence by organizing WAVE and N-WASP nucleation-promoting factor complexes
- Tsydenzhapova Ekaterina
- Fokin Artem
- David Nicolas
- Rocques Nathalie
- Polesskaya Anna
- Haddad Iman
- Vinh Joëlle
- Guérois Raphaël
- Gautreau Alexis
Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biology , 2026, pp.113443 . The function of the NHS gene that is responsible for the Nance-Horan Syndrome has remained elusive at the cellular level. Using CRISPR/Cas9, we inactivated the NHS gene in MCF10A cells and characterized the isoforms expressed in these cells. NHS KO cells displayed reduced migration persistence, a phenotype that was fully rescued by the long isoform 1 (i1) that contains a N-terminal WAVE Homology Domain (WHD), but only partially rescued by the short isoform 2 (i2), which does not. Patient mutations resulting in NHS proteins truncated at their C-terminus also reduced the ability of NHS i1 to rescue migration persistence. Using Tandem Affinity Purification (TAP) of NHS i1 and mass spectrometry, we identified as major NHS partners, all subunits of the WAVE Regulatory Complex (WRC) except WAVE subunits themselves, indicating that the WHD of NHS assembles a WAVE Shell Complex (WSC). The Arp2/3 complex and the Nucleation Promoting Factor (NPF) WAVE that activates it are critical for migration persistence. To investigate the role of the NHS-containing WSC, we performed TAP of the ABI1 subunit in parental and NHS KO cells and identified differential partners associated with ABI1 only in parental cells, but not in NHS KO cells. The most abundant of these were the WIPF2/N-WASP complex, which together with the kinase ABL2, was also critical for migration persistence. These results suggest that NHS controls cell migration by remodeling NPF complexes and their higher order assembly. (10.1016/j.jbc.2026.113443)
DOI : 10.1016/j.jbc.2026.113443
Fgfr3–Wnt signaling crosstalk is involved in maintaining cranial suture integrity
- Pereur Rachel
- Marc Yvan
- Lim Yuliya
- Schmitt Alain
- Malbouyres Marilyne
- Chessel Anatole
- Ruggiero Florence
- Schanne-Klein Marie-Claire
- Legeai-Mallet Laurence
- Dambroise Emilie
Bone Research, Springer Nature , 2026, 14 (1), pp.76 . Abstract Cranial suture formation is a dynamic process that requires precise cellular and molecular coordination to regulate bone growth and maintain suture homeostasis. The Fibroblast Growth Factor Receptor 3 (FGFR3) signaling pathway is among the major pathways disrupted in craniosynostosis; however, its precise role during cranial suture formation is still unknown. Using a relevant fgfr3 LoF zebrafish model exhibiting abnormal suture morphology, we demonstrated for the first time that Fgfr3 plays a pleiotropic role in both the formation and maintenance of cranial sutures. Transmission electron microscopy and second harmonic generation imaging revealed that Fgfr3 is essential for the proper organization of the collagen network within the suture. Using specific transgenic reporter lines, we showed that Fgfr3 is crucial for regulating osteogenesis in this region. Specifically, Fgfr3 limits the number of osteoprogenitors at the osteogenic front and promotes osteoblast maturation at the suture edge. RNAscope analyses further revealed that loss of Fgfr3 led to significant upregulation of fgf18 expression. Finally, our findings show that loss of Fgfr3 results in the activation of the canonical Wnt pathway, and possibly the BMP pathway, within cranial sutures. Pharmacological inhibition of canonical Wnt signaling during suture development using the β-catenin inhibitor XAV939 restored fgf18 expression, partially normalized levels of the BMP antagonist grem1 , reduced SMAD1/5 phosphorylation, and produced a significant improvement in cranial suture morphology. In conclusion, these findings position Fgfr3 as a central regulator of cranial suture formation and homeostasis, acting through intricate cross-talk between the FGF, canonical Wnt, and possibly BMP signaling pathways. These data offer new insights into the biology of cranial suture and FGFR3-related craniosynostoses. (10.1038/s41413-026-00558-w)
DOI : 10.1038/s41413-026-00558-w
Role of Neural Crest Cells in Establishing Corneal Transparency During Embryonic Development in Mice
- Ghoubay Djida
- Vidal Cécile
- Rappeneau Quentin
- Emini Jasmina
- Gitton Yorick
- Fouquet Stéphane
- Klein Marie‐claire Schanne
- Plamann Karsten
- Latour Gaël
- Borderie Vincent
Journal of Cellular Physiology, Wiley , 2026, 241 (8) . ABSTRACT Corneal transparency emerges during embryogenesis through the coordinated organization of neural crest–derived cells (NCCs) and extracellular matrix (ECM), yet the temporal and structural basis of this process remains incompletely defined. Here, we provide a multimodal, spatiotemporal analysis of mouse corneal development from embryonic Day 10 (E10) to birth (P0), combining whole‐mount and sectioned immunofluorescence, tissue clearing with three‐dimensional (3D) imaging, second harmonic generation (SHG) microscopy, full‐field optical coherence microscopy (FFOCM), and transmission electron microscopy (TEM). We show that early periocular mesenchyme is characterized by broad expression of neural crest‐associated markers (Sox9, HNK1), followed by progressive spatial restriction and downregulation as cells populate the corneal stroma. Sox10‐positive cells remain primarily associated with developing nerves and are largely excluded from the stromal compartment. Concomitantly, stromal cells undergo marked morphological transitions, from rounded to progressively flattened and elongated phenotypes, accompanying stromal expansion. Collagen deposition is first detected in the subepithelial region around E12 and increases thereafter, with SHG and TEM analyses revealing progressive organization and compaction of fibrillar networks. Quantitative ultrastructural analysis indicates dynamic changes in interfibrillar spacing during development, consistent with ongoing ECM remodeling. The emergence of a posterior‐to‐anterior gradient in cell morphology and matrix organization suggests a spatially coordinated maturation process across the stroma. Together, these findings provide an integrated structural framework linking NCCs dynamics, stromal cell differentiation, and ECM organization during murine corneal development. This work establishes a quantitative and multiscale atlas of corneal morphogenesis that informs how tissue architecture compatible with transparency is progressively established in vivo. (10.1002/jcp.70215)
DOI : 10.1002/jcp.70215
2,4-Bis{4-[(dialkylaminoalkyl)aminomethyl]phenyl}-7-substituted-7H-pyrrolo[2,3-d]pyrimidine Derivatives: Synthesis and Biological Evaluation as Novel Antiprotozoal Agents by Potentially Targeting G-Quadruplex
- Guillon Jean
- Savrimoutou Solène
- Agnamey Patrice
- Milano Vittoria
- Damiani Céline
- Ronga Luisa
- Hanot Marie
- Albenque Sandra
- Zangmo Tshering
- Monic Sarah
- Pinaud Noël
- Lari Lindita
- Marchivie Mathieu
- Moreau Stéphane
- Mergny Jean-Louis
- Moukha Serge
- Dozolme Pascale
- Boudot Clotilde
- Courtioux Bertrand
- Cohen Anita
- Sonnet Pascal
Scientia Pharmaceutica, MDPI , 2026, 94 (2), pp.48 . <p>A series of substituted pyrrolo[2,3-d]pyrimidines was designed, synthesized, and evaluated in vitro against two protozoan parasites: Plasmodium falciparum and Trypanosoma brucei brucei. Pharmacological studies revealed antiprotozoal activity with IC50 values in the submicromolar to micromolar range. Additionally, the in vitro cytotoxicity of these new compounds was assessed using human HepG2 cells. Among them, the pyrrolopyrimidine derivative 1d emerged as the most potent antimalarial compound, exhibiting a selectivity index (SI) of 600.81 against the P. falciparum chloroquine-resistant W2 strain. For the chloroquine-sensitive 3D7 strain, the most notable selectivity index (SI) was observed for pyrrolo[2,3-d]pyrimidine 1c, with a value of approximately 123. Furthermore, compound 1b demonstrated the most interesting activity against Trypanosoma brucei brucei, with an SI of 39.52, marking it as a promising trypanocidal agent. FRET melting assays confirmed that these nitrogen-containing heterocyclic compounds bind to telomeric G-quadruplexes in P. falciparum and Trypanosoma. However, no clear correlation was found between G-quadruplex binding and antiparasitic activity or selectivity, suggesting that G-quadruplex targeting is unlikely to be the main mechanism underlying cytotoxicity.</p> (10.3390/scipharm94020048)
DOI : 10.3390/scipharm94020048
Two-photon light-sheet live imaging at kilohertz frame rate using birefringence-based pulse splitting
- Zhu Lei
- Gottlieb Dale
- Maioli Vincent
- Hubert Antoine
- Druon Frédéric
- Mahou Pierre
- Beaurepaire Emmanuel
- Supatto Willy
Optica, Optical Society of America - OSA Publishing , 2026, 13 (6), pp.1086 . Multiphoton microscopy is widely used for imaging live and intact tissues. Its imaging speed, however, remains constrained by fluorophore emission rates and photodamage thresholds. In order to increase the effective pixel rate of a two-photon microscope beyond a few megahertz (MHz), multi-point acquisition schemes have been proposed. Two-photon (2P) light-sheet microscopy emerges as a particularly effective approach for high-speed multiphoton imaging of live specimens, as it enables parallelized excitation while minimizing the required increase in laser power. However, optimizing the signal-to-photodamage ratio in 2P light-sheet microscopy necessitates precise control over illumination parameters, including both wavelength and laser pulse repetition rate. Since conventional femtosecond laser sources generally do not allow independent modulation of these parameters, the development of low-cost, efficient, and robust strategies to modulate the temporal excitation profile is essential to fully exploit the advantages of 2P light-sheet microscopy. Here, we introduce a compact pulse-splitting scheme that meets these criteria. Our approach uses cascaded birefringent crystals to convert each excitation laser pulse into an adjustable sequence of collinear sub-pulses. We demonstrate its effectiveness in optimizing 2P light-sheet imaging of live zebrafish embryos. We analyze the impact of pulse splitting on photobleaching, nonlinear photodamage, and imaging performance. Additionally, we demonstrate high-speed 2P imaging of the beating heart and brain calcium dynamics using red fluorophores in live embryos. We achieve a kilohertz imaging frame rate, reaching more than 150 MHz pixel rates with fluorescent signal levels above 10photons⋅pixel −1 using a laser mean power and a peak intensity in the range of 100 mW and 0.1TW⋅cm −2 at the sample, respectively. This compact and adjustable pulse-splitting scheme allows full advantage to be taken of light-sheet illumination for fast in vivo 2P imaging. More generally, it facilitates the optimization of illumination parameters in multiphoton microscopy. (10.1364/OPTICA.588084)
DOI : 10.1364/OPTICA.588084
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
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
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
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
Resonant third harmonic generation in biological pigments
- Dees Stella
- Ferrer Ortas Júlia
- Mahou Pierre
- Supatto Willy
- Olivier Nicolas
- Beaurepaire Emmanuel
APL Photonics, AIP Publishing LLC , 2026, 11 (8), pp.086116 . Third harmonic generation (THG) microscopy provides label-free structural contrast of biological tissues. While the THG process can be enhanced by electronic transitions in absorbing molecules, knowledge of the third-order nonlinear properties of biological pigments is limited, and the potential of THG imaging for chemically selective imaging remains underutilized. In this study, we investigated resonant THG in pigments by performing nonlinear microspectroscopy in situ on three representative absorbers: hemoglobin in red blood cells, pteridines in xanthophores, and melanin in human hair. We measured THG spectra in the 1120–1300 nm excitation range. We observed a wavelength-dependent signal enhancement ranging from 10 to 100 times in these pigmented structures, depending on their respective absorption properties. We developed a numerical model of THG from interfaces, including resonant and non-resonant contributions, to interpret these observations. Our calculations reproduce key experimental trends, including resonance-induced enhancement factors and spectral properties. Finally, we demonstrate that third-order sum-frequency generation (TSFG) imaging provides spectroscopic contrast capable of distinguishing red blood cells from xanthophores in live zebrafish larvae. These results suggest that THG/TSFG is a promising approach to label-free, pigment-specific multiphoton imaging. (10.1063/5.0341777)
DOI : 10.1063/5.0341777
Self-referenced terahertz time-domain ATR spectroscopy of solutions
- Lordon Blandine
- Giraldo Betancur Susana
- Gallot Guilhem
Applied Physics Letters, American Institute of Physics , 2026, 128 (22), pp.221107 . Terahertz spectroscopy and imaging have emerged as sophisticated, nondestructive tools for material analysis in physical and biomedical sciences, owing to their sensitivity to molecular vibrations. However, the high absorption of terahertz radiation by water raises a significant challenge for studying liquids and biological samples. This work introduces a novel self-referenced time-domain attenuated total reflection (ATR) spectroscopy technique that overcomes this limitation by simultaneously recording both sample and reference terahertz waveforms. The method is based on ATR geometry, along with two time-delayed, synchronized sub-waveforms. This configuration enables precise differential measurements, thereby significantly improving detection sensitivity and long-term stability by mitigating environmental fluctuations and laser noise. The technique makes possible the direct extraction of both amplitude and phase information from the ATR reflection coefficient. The potential of this approach is demonstrated by measuring the relative power and phase spectra of NaCl, ATP, and saccharose solutions at various concentrations. The results obtained from this study indicate the presence of distinct spectral signatures for each molecule. This advancement opens novel prospects for high-fidelity spectral analysis, particularly in biomedical applications such as real-time monitoring of biochemical processes and cellular responses. (10.1063/5.0332458)
DOI : 10.1063/5.0332458
Corvis <sup>ST</sup> biomechanical indices in the diagnosis of corneal stromal and endothelial disorders: an artificial intelligence-based comparative study
- Borderie Vincent Michel
- Georgeon Cristina
- Louissi Nassim
- Memmi Benjamin
- Hamrani Malika
- Bouheraoua Nacim
- Chessel Anatole
British Journal of Ophthalmology, BMJ Publishing Group , 2026, 110, pp.396-402 . Aims: To analyse the value of the Corvis ST indices in diagnosing corneal stromal and endothelial disorders (CSEDs). Methods: This institutional retrospective case-control study included 903 eyes with a CSED and 597 normal eyes (controls), assessed with Corvis ST and MS39. Main outcome measures: Corvis ST indices. The collected data were divided into a training set (70%) and a test set (30%). Artificial intelligence frameworks were used to distinguish each disorder from controls and to classify corneas into seven groups: keratoconus, highrisk corneas for keratoconus, laser corneal refractive surgery (LCRS), endothelial disorders, stromal opacities, glaucoma corneas and normal corneas. Results: Stress-strain index (SSI) significantly increased with age in the control group. Compared with controls matched for age/sex, keratoconus was associated with Corvis Biomechanical Index (CBI) >0.51 (area under the curve, 0.99), Ambrósio's relational thickness horizontal (ARTh) <425.5 (0.97), deflection amplitude at the time of the first applanation (SPA-A1) <96.3 (0.97) and Pachy<522.4 µm (0.91); high-risk corneas with a difference in CBI between fellow eyes (CBI SYM) >0.14 (0.98), (L2) <1.95 (0.83) and Pachy<549.7 µm (0.71); LCRS with ARTh<455.1 (0.93) and CBI>0.35 (0.83); corneal endothelial disorders with Pachy SYM>19.7 µm (0.83), Pachy>569.1 µm (0.82) and CBI SYM>0.14 (0.77); stromal opacities with SPA-A1 SYM>11.8 (0.92), ARTh<569.9 (0.89), SSI SYM>0.14 (0.89) and CBI>0.22 (0.86). A logistic regression function using all indices reached an area under the receiver operating characteristic curve of 0.81 for glaucoma diagnosis. The TabPFN model provided the best accuracy (88.7%) for diagnosing the seven corneal conditions. SSI, SPA-A1, CBI and Pachy correlated with keratoconus grade. Keratoplasty for keratoconus improved but failed to restore normal corneal biomechanics. Conclusions: Corvis ST indices are relevant for diagnosing CESDs and distinguishing various disorders from each other. (10.1136/bjo-2025-327855)
DOI : 10.1136/bjo-2025-327855
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
On-axis and off-axis levitation by a rotating permanent magnet
- Schreckenberg Hugo
- El Omari El Alaoui Zayneb
- Gallot Guilhem
Physical Review E, American Physical Society (APS) , 2026, 113 (5), pp.055503 . A slightly tilted permanent magnet rotating at high speed can induce a magnetic field capable of trapping another permanent magnet in a gravity independent levitated bound state, bypassing Earnshaw's theorem. During levitation, the floater magnet is locked in a conical orbit at the same frequency as the rotor. This rotation allows the sides of the same polarity of each magnet to face each other, which is responsible for the dynamic equilibrium of the floater magnet. Here, we theoretically explain the motion of the floater in-axis and off-axis and highlight levitation stability conditions and their dependence on the size of the floater and the speed of the rotor. We also experimentally studied the levitation conditions with respect to the rotational speed of the rotor for various floater's sizes and shapes. We observed and analyzed the lower and upper limits of levitation. Finally, we explained the off-axis motion of the center of mass of the floater from its equilibrium position by an extension of the dipole moment model. (10.1103/5ysx-412r)
DOI : 10.1103/5ysx-412r
Dynamics and Catalytic Conversion of the CO 2 coproduct in Fatty Acid Photodecarboxylase
- Bonvalet Adeline
- Balduzzi Elsa
- Légeret Bertrand
- Antonucci Laura
- Samire Poutoum
- Solinas Xavier
- Peltier Gilles
- Beisson Frédéric
- Müller Pavel
- Joffre Manuel
- Hienerwadel Rainer
- Vos Marten
- Berthomieu Catherine
- Aleksandrov Alexey
- Sorigué Damien
ACS Catalysis, American Chemical Society , 2025, 16 (6), pp.5744-5756 . Fatty acid photodecarboxylase (FAP) converts fatty acids into hydrocarbons through a light-driven radical process. Earlier infrared and crystallographic studies proposed that part of the CO2 coproduct is converted to bicarbonate within FAP’s active site through reaction with a hydroxyl ion. To clarify the fate of CO2, we combined steady-state Fourier-transform and time-resolved infrared spectroscopies (FTIR and TRIR, respectively), membrane-inlet mass spectrometry (MIMS), site-directed mutagenesis, isotope-exchange experiments (H218O as solvent, 13C-labeled substrates), and quantum chemical and molecular dynamics simulations. At cryogenic temperatures (150–200 K), FTIR confirmed formation of bicarbonate in wild-type FAP photoexcited in H218O, with the expected isotopic shifts. Active site mutants with replaced Arg451 (R451K) or Cys432 (C432S) did not produce bicarbonate, demonstrating that both residues are required for this low-temperature reactivity. At room temperature, neither TRIR nor MIMS provided signals attributable to bicarbonate or mixed-isotope CO2, indicating that CO2 does not react with enzyme-bound water. Instead, CO2 exits FAP in two kinetic phases (∼1–2 μs and ∼400 μs) and exchanges isotopes only in bulk solvent. QM/MM simulations explain this temperature dependence: at 298 K, rapid reprotonation of Arg451 by Cys432 (barrier ≤ ∼11 kcal mol–1) prevents Arg451 from activating the water molecule for reaction with CO2, unlike at lower temperatures. These results revise the FAP photocycle by excluding bicarbonate as a room-temperature intermediate and point to a yet-unidentified CO2-derived species, motivating future time-resolved structural studies. (10.1021/acscatal.5c08787)
DOI : 10.1021/acscatal.5c08787
Deciphering the intermolecular interactions between G-quadruplex (G4)-forming sequences
- Xia Jianjun
- Zhou Jiahang
- Zhuang Xinzhe
- Ju Huangxian
- Monchaud David
- Chaires Jonathan B
- Šponer Jiří
- Mergny Jean-Louis
- Zhou Jun
Nucleic Acids Research, Oxford University Press , 2025, 53 (22) . <div><p>Interactions between biomolecules govern cellular biology. While protein/protein and protein/nucleic acid (DNA, RNA) interactions-and, to a lesser extent, RNA/RNA and RNA/DNA interactions-ha v e been e xtensiv ely described, a question remains as to whether and how non-canonical DNA str uct ures might interact with each other. This is of particular interest for guanine (G)-rich sequences that can fold into G-quadruplex (G4) str uct ures: Individual G4s are currently studied for their involvement in a myriad of cellular events (mostly pertaining to the control of gene expression), and, more recently, the interactions between two G4s have been scrutinized as being part of a novel gene expression regulatory mechanism in v olving chromatin remodeling through G4-mediated loop f ormation. T he question that needs to be answered is whether G4s or their corresponding G-rich sequences are in v olv ed. We present here a series of results collected using a combination of sequences, experimental conditions, and tec hniques, whic h led us to the conclusion that G4/G4 intermolecular interactions are mostly go v erned b y primary sequence interactions in vitro.</p></div> (10.1093/nar/gkaf1288)
DOI : 10.1093/nar/gkaf1288
Label-free nonlinear microscopy probes cellular metabolism and myelin dynamics in live tissue
- Asadipour Bahar
- Morizet Josephine
- Ronzano Remi
- Zhang Xingjian
- Aigrot Marie-Stephane
- Mahou Pierre
- Solinas Xavier
- Phan Minh Son
- Chessel Anatole
- Stankoff Bruno
- Desmazieres Anne
- Beaurepaire Emmanuel
- Stringari Chiara
Communications Biology, Nature Publishing Group , 2025 . Metabolic coupling between neurons and glial cells plays a critical role in brain activity and myelin plasticity. Understanding its role in physiological and pathological contexts requires advanced methods to map metabolism and myelin in live tissue with high spatiotemporal resolution. Here, we present a label-free, multimodal, nonlinear optical microscopy platform integrated with an advanced image processing framework that simultaneously maps cellular metabolism and myelin distribution in organotypic cerebellar cultures. We combine third-harmonic generation microscopy for high-resolution myelin imaging with single axon precision with two-photon fluorescence lifetime microscopy of NAD(P)H metabolic biomarker to assess redox states with single-cell resolution. We introduce automated image analysis methods for cell segmentation and myelinated axon detection, enabling quantitative metabolic and myelin assessment in intact tissue during experimental myelination, demyelination and remyelination. Using this framework, we map the 3D myelin distribution in cerebellar folia and identify distinct metabolic signatures in neurons, oligodendrocytes, and microglia. Furthermore, we measure a metabolic shift in microglia along with myelin distribution changes during experimental demyelination. In conclusion, we establish label-free optical imaging as a powerful tool for the non-invasive characterization of neuro-glial metabolic coupling and myelin organization in living brain tissue, opening new perspectives for research in neuroinflammation and neurodegeneration. (10.1038/s42003-025-09192-4)
DOI : 10.1038/s42003-025-09192-4
Genome-wide ribonucleotide detection in <i>Archaea</i>
- Moalic Yann
- Reveil Maurane
- Kundnani Deepali L
- Balachander Sathya
- Yang Taehwan
- Gombolay Alli
- Ranjbarian Farahnaz
- Brizard Raphael
- Durand Patrick
- Myllykallio Hannu
- Jebbar Mohamed
- Hofer Anders
- Storici Francesca
- Henneke Ghislaine
Nucleic Acids Research, Oxford University Press , 2025, 53 (21) . <div><p>Genome integrity is constantly challenged by the incorporation of ribonucleotides ribonucleoside monophosphates (rNMPs) during DNA synthesis. Co v alently link ed single and se v eral consecutiv e rNMPs occur in the genome of a number of organisms. T he y are mainly introduced by DNA polymerases during DNA replication and repair. In general, cells evolved ribonucleases H (RNases H) specialized in the removal of rN-MPs from DNA to a v oid an y detrimental consequences on genome st abilit y. Here, we describe the in v olv ement of types 1 and/or 2 RNases H in processing embedded rNMPs in the genome of two archaeal species Haloferax volcanii and Thermococcus barophilus . Genome-wide, nucleotide-resolution maps of embedded rNMPs re v eal oriC -centered strand-switching profiles in H. volcanii rnhB , indicating origin firing in native cells, while their absence in T. barophilus reflects low origin usage. The data also define archaeal sequence-context rules for rNMP embedment, confirm the predominant role of RNase HII in rNMP remo v al with e vidence of compensatory repair pathw a y s, and link incorporation patterns to measured rNTP/dNTP pools. Together, these findings unco v er archaeal-specific mechanisms of rNMP incorporation and repair with implications for replication and genome st abilit y.</p></div> (10.1093/nar/gkaf1231)
DOI : 10.1093/nar/gkaf1231
Consensus guidelines for cellular label-free optical metabolic imaging: ensuring accuracy and reproducibility in metabolic profiling
- Georgakoudi Irene
- Skala Melissa
- Quinn Kyle
- Stringari Chiara
- Sorrells Janet
- Heikal Ahmed
- Li Lin
- Xu He
- You Sixian
- Walsh Alex
- Datta Rupsa
- Samimi Kayvan
- Gillette Amani
- Eliceiri Kevin
- Balu Mihaela
- Boppart Stephen
- Digman Michelle
- Dunning Kylie
- Evans Conor
- Garcia Alba Alfonso
- Houston Jessica
- Hwang Wonsang
- Lindley Matthew
- Li Xingde
- Liu Zhiyi
- Marcu Laura
- Murugkar Sangeeta
- Nichols Michael
- Niesner Raluca
- Parekh Sapun
- Rajaram Narasimhan
- Ranjit Suman
- Shen Keyue
- Shi Lingyan
- Torrado Belén
- Vallmitjana Alexander
- Wang-Evers Michael
- Zemp Roger
Journal of Biomedical Optics, Society of Photo-optical Instrumentation Engineers , 2025, 30 (S2), pp.S23901 . Significance: Cellular metabolism plays a central role in health and disease, making its study critical for advancing diagnostics and therapies. Label-free optical metabolic imaging using endogenous fluorescence from reduced nicotinamide adenine dinucleotide (phosphate) [NAD(P)H] and flavin adenine dinucleotide (FAD) provides nondestructive, high-resolution insights into metabolic function and heterogeneity from the sub-cellular to the tissue level. Standardized approaches are essential to ensure reproducibility and comparability across studies. Aim: We aim to establish a consensus framework for the acquisition, calibration, and reporting of microscopic imaging metabolic function assessments based on fluorescence intensity and lifetime measurements of NAD(P)H and FAD. Approach: We present best practices for calibrating, analyzing, and reporting fluorescence intensity-based optical redox ratios and fluorescence lifetime data using multiexponential fitting and phasor analysis. Guidelines for validation experiments and cross-system standardization are provided to improve accuracy and reproducibility. Results: We demonstrate the importance of calibration procedures and normalization strategies for intensity-based optical redox measurements. We highlight needed calibration, signal-to-noise ratio considerations, and the impact of distinct analytical approaches on fluorescence lifetime-based metabolic function metrics. Conclusion: We recommend a consistent, practical framework for reproducible, label-free, optical metabolic imaging, facilitating robust comparisons across studies and supporting the broader adoption of optical metabolic imaging technologies for biomedical research and clinical translation. (10.1117/1.JBO.30.S2.S23901)
DOI : 10.1117/1.JBO.30.S2.S23901
Designing an ecofriendly catalyst for a sustainable use of water resources
- Qiu Dehui
- Zhang Xiaobo
- Tian Fan
- Liu Yuan
- He Fangni
- Yan Xinrong
- Wei Shijiong
- Mergny Jean-Louis
- Monchaud David
- Zhang Shujuan
- Ju Huangxian
- Zhou Jun
National Science Review, Oxford Academic , 2025, 13 (2), pp.nwaf447 . The printing and dyeing industry is one of the most polluting ( ∼20% of global clean water pollution), water-consuming and energy-wasting sectors in the manufacturing field, highlighting the need to find green catalysts to improve its sustainability. Herein, a novel artificial green catalyst was developed, known as a bifunctional chimeric peptide DNAzyme (bi-CPDzyme), comprising peptide, DNA and hemin moieties. This catalyst displays both catalase (CAT) and peroxidase (POD) activities. The turnover number ( k cat ) of the optimized bi-CPDzyme prototype (G-quadruplex-Hemin-HRRHKHRRH) surpasses the natural CAT/POD bifunctional enzyme KatG, and competes with individual CAT and POD enzymes. This remarkable performance is attributed to the strategic combination and incorporation of histidine (H) and arginine (R) residues, which effectively trap hydrogen peroxide (H 2 O 2 ) near the catalytic center via hydrogen bond formation, thus facilitating the generation of the active intermediate compound I, as supported here by theoretical calculations. Significantly, bi-CPDzyme achieves efficient decomposition of bleaching-derived residual H 2 O 2 in a water-/energy-saving manner, while degrading dyes from textile industry effluents even in complex real samples, in addition to being easily recyclable and implementable. These findings make bi-CPDzyme a cutting-edge and environmentally friendly catalyst, positioning it at the forefront of advancements towards creating a sustainable society. (10.1093/nsr/nwaf447)
DOI : 10.1093/nsr/nwaf447
Ultrafast photooxidation of semireduced flavin in fatty acid photodecarboxylase
- Vos Marten
- Balduzzi Elsa
- Sorigué Damien
- Aleksandrov Alexey
Science Advances, American Association for the Advancement of Science (AAAS) , 2025, 11 (38) . The initial photoproduct of the natural photoenzyme fatty acid photodecarboxylase involves the flavin anion radical flavin adenine dinucleotide (FAD •– ). Using spectrally resolved ultrafast transient absorption spectroscopy, we demonstrate that FAD •– photoexcitation in the absence of substrate leads to the formation of the oxidized flavin FAD ox (the resting state in the catalytic cycle) within 100 femtoseconds. While this feature is similar to that occurring in flavoprotein oxidases, the ensuing photocycle is more complex. Upon excitation at the lowest-energy transition, the ejected electron is initially captured as a hydrated electron ( e – H ) before transferring to a secondary acceptor in 2.5 picoseconds and returning to the flavin in 37 picoseconds. This implies that e – H can be generated within a protein environment, an unprecedented finding. This assessment is supported by molecular dynamics simulations showing an expansion of the flavin-binding pocket without substrate, allowing water molecules to fill the void. Our results may pave the way to developing unconventional photocatalytic processes. (10.1126/sciadv.adz1904)
DOI : 10.1126/sciadv.adz1904
A Selective and Sensitive Method for Colistin Detection by G-Quadruplex Ligand Competition
- Wei Shijiong
- Qiu Dehui
- Yan Xinrong
- Liu Bin
- Mergny Jean-Louis
- Monchaud David
- Ju Huangxian
- Zhou Jun
Analytical Chemistry, American Chemical Society , 2025, 97 (31), pp.16805 . Colistin (COL) is a widely used antibiotic and is quite often used as a last-resort treatment option for treating multidrug-resistant Gram-negative bacterial infections. Due to its widespread use, COL accumulates in nature, which represents a novel ecological and health threat. However, there is currently no rapid and specific method available for titrating COL levels in collected samples. Herein, we report a simple chemiluminescence detection method based on the specific interaction between COL and a parallel G-quadruplex (G4). To this end, we exploit the catalytic properties of the G4/hemin DNAzyme, which is able to oxidize substrates to provide a readily monitored readout. The stronger affinity of G4 for COL versus hemin allows for the inactivation of the G4/hemin DNAzyme, which is used herein to quantify COL in solution. Through a series of optimizations, we identified the best G4 sequence (F3TC), oxidation substrate (luminol), and experimental conditions, which allow for the detection of COL over a broad concentration window, from 0.5 to 2,500 ng/mL, with a detection limit of 0.4 ng/mL and excellent selectivity against other antibiotics. Compared with existing methods, the proposed approach provides a simpler and label-free quantification of COL, which might serve as a valuable standard method for antibiotic detection, whose use was validated under real conditions herein (10.1021/acs.analchem.5c01733)
DOI : 10.1021/acs.analchem.5c01733
Design, synthesis, biophysical and biological evaluation of original condensed pyrrolopyrimidine and pyrrolopyridine ligands as anti-SARS-CoV-2 agents targeting G4
- Guillon Jean
- Savrimoutou Solène
- da Rocha Nicolas
- Albenque-Rubio Sandra
- Helynck Olivier
- Durand Cyrielle
- Chiaravalli Jeanne
- Pinaud Noël
- Ronga Luisa
- Moreau Stéphane
- Chirold Simon
- Zangmo Tshering
- Arab Melika
- Lari Lindita
- Mergny Jean‐louis
- Munier-Lehmann Hélène
- Lavigne Marc
European Journal of Medicinal Chemistry, Elsevier , 2025, 292, pp.117655 . The design and synthesis of novel bis[(substituted-aminomethyl)phenyl]phenyl pyrrolopyrimidines, pyrrolopyridines, pyrazolopyrimidines, imidazopyrimidines, and tris[(substituted-aminomethyl)phenyl]phenyl pyrrolopyrimidines are reported here. These original G-quadruplex (G4) ligands have been then subjected to a screening on SARS-CoV-2 using a competition HTRF assay by targeting the SUD-NM/TRF2 RNA G4 interaction. The more promising derivatives have been evaluated in vitro to determine their potential antiviral effect on two different cell lines infected by two SARS-CoV-2 strains. This study revealed a clear correlation between their antiviral property and their efficacy to prevent the SUD/G4 interaction. This correlation supports the choice of SUD/RNA G4 complexes formed during SARS-CoV-2 infection as new antiviral targets (10.1016/j.ejmech.2025.117655)
DOI : 10.1016/j.ejmech.2025.117655
Chromium‐Doped Zinc Gallate Nanoparticles for Enhanced Enzyme‐Linked Immunosorbent Assay Sensitivity: Optimization of Synthesis and Functionalization Strategies for Ultra‐Low IgG Detection
- Ferjaoui Zied
- Liu Jianhua
- Matuszewska Celina
- Chanéac Corinne
- Viana Bruno
- Bouzigues Cédric
- Scherman Daniel
- Mignet Nathalie
- Richard Cyrille
Small Science, Wiley , 2025, 5 (10) . The use of zinc gallate nanoparticles (ZnGa 2 O 4 :Cr 3+ ) (ZGO‐NPs) presents significant potential for improving the sensitivity in enzyme‐linked immunosorbent assays (ELISA). The persistent luminescence signal increase of these nanoparticles in the presence of hydrogen peroxide (H 2 O 2 ) offers advantages for the sensitive detection of biomolecules. Herein, different conditions of ZGO synthesis have been investigated by varying the hydrothermal reaction duration (6, 12, and 24 h) and examining its impact in the presence of H 2 O 2 . These nanoparticles have been integrated into ELISA assays, using as target antigen IgG. The lowest limit of detection (LOD) of 0.2 pg mL −1 is observed for ZGO‐NPs prepared during 12 h (ZGO2), and with a detection range from 1 to 1000 pg mL −1 . The impact of covalently functionalizing these nanoparticles has then been assessed. First using glucose oxidase (GOx) and the detection antibody (Ab D ) linked to PEGylated ZGO‐NPs, named ZGO‐GOx‐Ab D . Alternatively, only the detection antibody is linked to the PEG ZGO‐NPs, named ZGO‐Ab D . The results show a significant lowering of the LOD when using the functionalized ZGO2 NPs and also highlight the impact of the signal amplification by H 2 O 2 . Specifically, when using ZGO2‐GOx‐Ab D incubated with glucose to produce H 2 O 2 , or with ZGO2‐Ab D to which H 2 O 2 was added, the LODs are ≈98 and 56 fg mL −1 respectively, with detection ranges from 0.01 to 100 pg mL −1 . (10.1002/smsc.202500177)
DOI : 10.1002/smsc.202500177