Rapid 40S scanning and its regulation by mRNA structure during eukaryotic translation initiation.

How the eukaryotic 43S preinitiation complex scans along the 5' untranslated region (5' UTR) of a capped mRNA to locate the correct start codon remains elusive. Here, we directly track yeast 43S-mRNA binding, scanning, and 60S subunit joining by real-time single-molecule fluorescence spectroscopy. 43S engagement with mRNA occurs through a slow, ATP-dependent process driven by multiple initiation factors including the helicase eIF4A. Once engaged, 43S scanning occurs rapidly and directionally at ∼100 nucleotides per second, independent of multiple cycles of ATP hydrolysis by RNA helicases post ribosomal loading. Scanning ribosomes can proceed through RNA secondary structures, but 5' UTR hairpin sequences near start codons drive scanning ribosomes at start codons backward in the 5' direction, requiring rescanning to arrive once more at a start codon. Direct observation of scanning ribosomes provides a mechanistic framework for translational regulation by 5' UTR structures and upstream near-cognate start codons.

CENP-B-mediated DNA loops regulate activity and stability of human centromeres.

Chromosome inheritance depends on centromeres, epigenetically specified regions of chromosomes. While conventional human centromeres are known to be built of long tandem DNA repeats, much of their architecture remains unknown. Using single-molecule techniques such as AFM, nanopores, and optical tweezers, we find that human centromeric DNA exhibits complex DNA folds such as local hairpins. Upon binding to a specific sequence within centromeric regions, the DNA-binding protein CENP-B compacts centromeres by forming pronounced DNA loops between the repeats, which favor inter-chromosomal centromere compaction and clustering. This DNA-loop-mediated organization of centromeric chromatin participates in maintaining centromere position and integrity upon microtubule pulling during mitosis. Our findings emphasize the importance of DNA topology in centromeric regulation and stability.

S1-END-seq reveals DNA secondary structures in human cells.

DNA becomes single stranded (ssDNA) during replication, transcription, and repair. Transiently formed ssDNA segments can adopt alternative conformations, including cruciforms, triplexes, and quadruplexes. To determine whether there are stable regions of ssDNA in the human genome, we utilized S1-END-seq to convert ssDNA regions to DNA double-strand breaks, which were then processed for high-throughput sequencing. This approach revealed two predominant non-B DNA structures: cruciform DNA formed by expanded (TA)n repeats that accumulate in microsatellite unstable human cancer cell lines and DNA triplexes (H-DNA) formed by homopurine/homopyrimidine mirror repeats common across a variety of cell lines. We show that H-DNA is enriched during replication, that its genomic location is highly conserved, and that H-DNA formed by (GAA)n repeats can be disrupted by treatment with a (GAA)n-binding polyamide. Finally, we show that triplex-forming repeats are hotspots for mutagenesis. Our results identify dynamic DNA secondary structures in vivo that contribute to elevated genome instability.

Replication-induced DNA secondary structures drive fork uncoupling and breakage.

Sequences that form DNA secondary structures, such as G-quadruplexes (G4s) and intercalated-Motifs (iMs), are abundant in the human genome and play various physiological roles. However, they can also interfere with replication and threaten genome stability. Multiple lines of evidence suggest G4s inhibit replication, but the underlying mechanism remains unclear. Moreover, evidence of how iMs affect the replisome is lacking. Here, we reconstitute replication of physiologically derived structure-forming sequences to find that a single G4 or iM arrest DNA replication. Direct single-molecule structure detection within solid-state nanopores reveals structures form as a consequence of replication. Combined genetic and biophysical characterisation establishes that structure stability and probability of structure formation are key determinants of replisome arrest. Mechanistically, replication arrest is caused by impaired synthesis, resulting in helicase-polymerase uncoupling. Significantly, iMs also induce breakage of nascent DNA. Finally, stalled forks are only rescued by a specialised helicase, Pif1, but not Rrm3, Sgs1, Chl1 or Hrq1. Altogether, we provide a mechanism for quadruplex structure formation and resolution during replication and highlight G4s and iMs as endogenous sources of replication stress.

Co-temporal Force and Fluorescence Measurements Reveal a Ribosomal Gear Shift Mechanism of Translation Regulation by Structured mRNAs.

The movement of ribosomes on mRNA is often interrupted by secondary structures that present mechanical barriers and play a central role in translation regulation. We investigate how ribosomes couple their internal conformational changes with the activity of translocation factor EF-G to unwind mRNA secondary structures using high-resolution optical tweezers with single-molecule fluorescence capability. We find that hairpin opening occurs during EF-G-catalyzed translocation and is driven by the forward rotation of the small subunit head. Modulating the magnitude of the hairpin barrier by force shows that ribosomes respond to strong barriers by shifting their operation to an alternative 7-fold-slower kinetic pathway prior to translocation. Shifting into a slow gear results from an allosteric switch in the ribosome that may allow it to exploit thermal fluctuations to overcome mechanical barriers. Finally, we observe that ribosomes occasionally open the hairpin in two successive sub-codon steps, revealing a previously unobserved translocation intermediate.

Transcription factor Wilms' tumor 1 regulates developmental RNAs through 3' UTR interaction.

Wilms' tumor 1 (WT1) is essential for the development and homeostasis of multiple mesodermal tissues. Despite evidence for post-transcriptional roles, no endogenous WT1 target RNAs exist. Using RNA immunoprecipitation and UV cross-linking, we show that WT1 binds preferentially to 3' untranslated regions (UTRs) of developmental targets. These target mRNAs are down-regulated upon WT1 depletion in cell culture and developing kidney mesenchyme. Wt1 deletion leads to rapid turnover of specific mRNAs. WT1 regulates reporter gene expression through interaction with 3' UTR-binding sites. Combining experimental and computational analyses, we propose that WT1 influences key developmental and disease processes in part through regulating mRNA turnover.

Igniting taxonomic curiosity: The amazing story of Amazonocrinis with the description of a new genus Ahomia gen. nov. and novel species of Ahomia, Amazonocrinis, and Dendronalium from the biodiversity-rich northeast region of India.

Five cyanobacterial strains exhibiting Nostoc-like morphology were sampled from the biodiversity hotspots of the northeast region of India and characterized using a polyphasic approach. Molecular and phylogenetic analysis using the 16S rRNA gene indicated that the strains belonged to the genera Amazonocrinis and Dendronalium. In the present investigation, the 16S rRNA gene phylogeny clearly demarcated two separate clades of Amazonocrinis. The strain MEG8-PS clustered along with Amazonocrinis nigriterrae CENA67, which is the type strain of the genus. The other three strains ASM11-PS, RAN-4C-PS, and NP-KLS-5A-PS clustered in a different clade that was phylogenetically distinct from the Amazonocrinis sensu stricto clade. Interestingly, while the 16S rRNA gene phylogeny exhibited two separate clusters, the 16S-23S ITS region analysis did not provide strong support for the phylogenetic observation. Subsequent analyses raised questions regarding the resolving power of the 16S-23S ITS region at the genera level and the associated complexities in cyanobacterial taxonomy. Through this study, we describe a novel genus Ahomia to accommodate the members clustering outside the Amazonocrinis sensu stricto clade. In addition, we describe five novel species, Ahomia kamrupensis, Ahomia purpurea, Ahomia soli, Amazonocrinis meghalayensis, and Dendronalium spirale, in accordance with the International Code of Nomenclature for algae, fungi, and plants (ICN). Apart from further enriching the genera Amazonocrinis and Dendronalium, the current study helps to resolve the taxonomic complexities revolving around the genus Amazonocrinis and aims to attract researchers to the continued exploration of the tropical and subtropical cyanobacteria for interesting taxa and lineages.

2,2'-Tethered Binaphthyl-Embedded One-Handed Helical Ladder Polymers: Impact of the Tether Length on Helical Geometry and Chiroptical Property.

Synthetic breakthroughs diversify the molecules and polymers available to chemists. We now report the first successful synthesis of a series of optically-pure 2,2'-tethered binaphthyl-embedded helical ladder polymers based on quantitative and chemoselective ladderization by the modified alkyne benzannulations using the 4-alkoxy-2,6-dimethylphenylethynyl group as the alkyne source, inaccessible by the conventional approach lacking the 2,6-dimethyl substituents. Due to the defect-free helix formation, the circular dichroism signal increased by more than 6 times the previously reported value. The resulting helical secondary structure can be fine-tuned by controlling the binaphthyl dihedral angle in the repeating unit with variations in the 2,2'-alkylenedioxy tethering groups by one carbon atom at a time. The optimization of the helical ladder structures led to a strong circularly polarized luminescence with a high fluorescence quantum yield (28 %) and luminescence dissymmetry factor (2.6×10-3 ).

Automatic generation of pseudoknotted RNAs taxonomy.

BACKGROUND: The ability to compare RNA secondary structures is important in understanding their biological function and for grouping similar organisms into families by looking at evolutionarily conserved sequences such as 16S rRNA. Most comparison methods and benchmarks in the literature focus on pseudoknot-free structures due to the difficulty of mapping pseudoknots in classical tree representations. Some approaches exist that permit to cluster pseudoknotted RNAs but there is not a general framework for evaluating their performance. RESULTS: We introduce an evaluation framework based on a similarity/dissimilarity measure obtained by a comparison method and agglomerative clustering. Their combination automatically partition a set of molecules into groups. To illustrate the framework we define and make available a benchmark of pseudoknotted (16S and 23S) and pseudoknot-free (5S) rRNA secondary structures belonging to Archaea, Bacteria and Eukaryota. We also consider five different comparison methods from the literature that are able to manage pseudoknots. For each method we clusterize the molecules in the benchmark to obtain the taxa at the rank phylum according to the European Nucleotide Archive curated taxonomy. We compute appropriate metrics for each method and we compare their suitability to reconstruct the taxa.

R-loop formation during S phase is restricted by PrimPol-mediated repriming.

During DNA replication, conflicts with ongoing transcription are frequent and require careful management to avoid genetic instability. R-loops, three-stranded nucleic acid structures comprising a DNA:RNA hybrid and displaced single-stranded DNA, are important drivers of damage arising from such conflicts. How R-loops stall replication and the mechanisms that restrain their formation during S phase are incompletely understood. Here, we show in vivo how R-loop formation drives a short purine-rich repeat, (GAA)10, to become a replication impediment that engages the repriming activity of the primase-polymerase PrimPol. Further, the absence of PrimPol leads to significantly increased R-loop formation around this repeat during S phase. We extend this observation by showing that PrimPol suppresses R-loop formation in genes harbouring secondary structure-forming sequences, exemplified by G quadruplex and H-DNA motifs, across the genome in both avian and human cells. Thus, R-loops promote the creation of replication blocks at susceptible structure-forming sequences, while PrimPol-dependent repriming limits the extent of unscheduled R-loop formation at these sequences, mitigating their impact on replication.

G-Quadruplexes as Key Transcriptional Regulators in Neglected Trypanosomatid Parasites.

G-quadruplexes (G4s) are nucleic acid secondary structures that have been linked to the functional regulation of eukaryotic organisms. G4s have been extensively characterised in humans and emerging evidence suggests that they might also be biologically relevant for human pathogens. This indicates that G4s might represent a novel class of therapeutic targets for tackling infectious diseases. Bioinformatic studies revealed a high prevalence of putative quadruplex-forming sequences (PQSs) in the genome of protozoans, which highlights their potential roles in regulating vital processes of these parasites, including DNA transcription and replication. In this work, we focus on the neglected trypanosomatid parasites, Trypanosoma and Leishmania spp., which cause debilitating and deadly diseases across the poorest populations worldwide. We review three examples where G4-formation might be key to modulate transcriptional activity in trypanosomatids, providing an overview of experimental approaches that can be used to exploit the regulatory roles and relevance of these structures to fight parasitic infections.

Impact of Peptide Sequences on Their Structure and Function: Mimicking of Virus-Like Nanoparticles for Nucleic Acid Delivery.

We rationally designed a series of amphiphilic hepta-peptides enriched with a chemically conjugated guanidiniocarbonylpyrrole (GCP) unit at the lysine side chain. All peptides are composed of polar (GCP) and non-polar (cyclohexyl alanine) residues but differ in their sequence periodicity, resulting in different secondary as well as supramolecular structures. CD spectra revealed the assembly of ß-sheet-, α-helical and random structures for peptides 1, 2 and 3, respectively. Consequently, this enabled the formation of distinct supramolecular assemblies such as fibres, nanorod-like or spherical aggregates. Notably, all three cationic peptides are equipped with the anion-binding GCP unit and thus possess a nucleic acid-binding centre. However, only the helical (2) and the unstructured (3) peptide were able to assemble into small virus-like DNA-polyplexes and effectively deliver DNA into cells. Notably, as both peptides (2 and 3) were also capable of siRNA-delivery, they could be utilized to downregulate expression of the caner-relevant protein Survivin.

Polymorphisms of rDNA genes in Cyberlindnera yeast suggest birth-and-death evolution events.

In eukaryotes, the ribosome machinery is encoded by repeats of the ribosomal RNA genes: 26/28S, 18S, 5.8S, and 5S, structured in tandem arrays and frequently homogenized within a genome. This homogenization is thought to be driven by concerted evolution, evolving as a unit, which contributes to its target as the species barcode in modern taxonomy. However, high heterogeneity of rDNA genes has been reported, including in Saccharomycotina yeasts. Here, we describe the polymorphisms and heterogeneity of D1/D2 domains (26S rRNA) and the intergenic transcribed spacer of a new yeast species with affinities to the genus Cyberlindnera and their evolution. Both regions are not homogenized, failing the prediction of concerted evolution. Phylogenetic network analysis of cloned sequences revealed that Cyberlindnera sp. rDNAs are diverse and evolved by reticulation rather than by bifurcating tree evolution model. Predicted rRNA secondary structures also confirmed structural differences, except for some conserved hairpin loops. We hypothesize that some rDNA is inactive within this species and evolves by birth-and-death rather than concerted evolution. Our findings propel further investigation into the evolution of rDNA genes in yeasts.

Structure and in vitro digestion characteristics of skim goat milk protein during processing: effects of fat separation.

BACKGROUND: Although nonfat milk has been used worldwide in the industrial dairy process, little is known about the effects of fat separation during the manufacturing process on skim milk's structural and digestive properties. This study investigated the effects of the manufacturing process on the structure and in vitro digestion properties of skim goat milk, particularly emphasizing fat separation. RESULTS: Changes in the surface charge and hydrophobicity of milk proteins caused by fat separation resulted in oxidation and aggregation in the subsequent homogenization, heat and spray-drying processing, which affected its digestibility. Compared with separation by dish separator (DS), skim milk after tubular centrifugal separation (CS) showed a higher initial and final digestibility. The CS samples also had a lower surface hydrophobicity level and higher free sulfhydryl content, ζ-potential, and average particle size (P < 0.05). Goat milk protein after CS was more readily oxidized and aggregated during the subsequent homogenization and heat treatment, as evidenced by the higher carbonyl content and particle size. Centrifugal separation also converted more ß-sheets to α-helices, thus promoting the aggregation of oxidized skim milk protein. CONCLUSION: The skim milk after CS and DS demonstrated different structural and digestive properties. Skim goat milk products after CS were more susceptible to oxidant-induced protein structural changes, resulting in higher protein digestibility. These findings provide insights into the mechanism involved in the control of gastric digestion of skim milk during manufacturing process. © 2023 Society of Chemical Industry.

Self-Activated Formation of Hierarchical Co3 O4 Nanoflakes with High Valence-State Conversion Capability for Ultrahigh-Capacity Zn-Co Batteries.

Cobalt-based materials are attracting increasing interest in alkaline Zn batteries due to the high theoretical capacity. However, the practical utilization is restricted by the poor microstructure and insufficient valence-state conversion. Herein, a self-activated formation of hierarchical Co3 O4 nanoflakes with high valence-state conversion capability is designed. This electrode not only exhibits the optimized microstructure with large reaction surfaces, but also shows excellent valence-state conversion capability. Consequently, this battery delivers an ultrahigh capacity of 481.4 mAh g-1 and an energy density of 818.3 Wh kg-1 based on the active material, which shines among reported Co-based materials. Besides, the capacity can retain 41.9% with even 20× current density increases, and it can operate with a capacity decay of 20% after the 1000th cycle. This strategy greatly enhances the performance and durability of integrated air electrodes, raising the attention of boundary design for other electrochemical energy conversion and storage devices.

Impact of bPNA Backbone Structural Constraints and Composition on Triplex Hybridization with DNA.

We report herein a study on the impact of bifacial peptide nucleic acid (bPNA) amino acid composition and backbone modification on DNA binding. A series of bPNA backbone variants with identical net charge were synthesized to display either 4 or 6 melamine (M) bases. These bases form thymine-melamine-thymine (TMT) base-triples, resulting in triplex hybrid stem structures with T-rich DNAs. Analyses of 6 M bPNA-DNA hybrids suggested that hybrid stability was linked to amino acid secondary structure propensities, prompting a more detailed study in shorter 4 M bPNAs. We synthesized 4 M bPNAs predisposed to adopt helical secondary structure via helix-turn nucleation in 7-residue bPNAs using double-click covalent stapling. Generally, hybrid stability improved upon stapling, but amino acid composition had a more significant effect. We also pursued an alternative strategy for bPNA structural preorganization by incorporation of residues with strong backbone amide conformational preferences such as 4R- and 4S-fluoroprolines. Notably, these derivatives exhibited an additional improvement in hybrid stability beyond both unsubstituted proline bPNA analogues and the helically patterned bPNAs. Overall, these findings demonstrate the tunability of bPNA-DNA hybrid stability through bPNA backbone structural propensities and amino acid composition.

Synthetic α-Helical Peptides as Potential Inhibitors of the ACE2 SARS-CoV-2 Interaction.

During viral cell entry, the spike protein of SARS-CoV-2 binds to the α1-helix motif of human angiotensin-converting enzyme 2 (ACE2). Thus, alpha-helical peptides mimicking this motif may serve as inhibitors of viral cell entry. For this purpose, we employed the rigidified diproline-derived module ProM-5 to induce α-helicity in short peptide sequences inspired by the ACE2 α1-helix. Starting with Ac-QAKTFLDKFNHEAEDLFYQ-NH2 as a relevant section of α1, a series of peptides, N-capped with either Ac-ßHAsp-[ProM-5] or Ac-ßHAsp-PP, were prepared and their α-helicities were investigated. While ProM-5 clearly showed a pronounced effect, an even increased degree of helicity (up to 63 %) was observed in sequences in which non-binding amino acids were replaced by alanine. The binding affinities of the peptides towards the spike protein, as determined by means of microscale thermophoresis (MST), revealed only a subtle influence of the α-helical content and, noteworthy, led to the identification of an Ac-ßHAsp-PP-capped peptide displaying a very strong binding affinity (KD =62 nM).

Current status of PTMs structural databases: applications, limitations and prospects.

Protein 3D structures, determined by their amino acid sequences, are the support of major crucial biological functions. Post-translational modifications (PTMs) play an essential role in regulating these functions by altering the physicochemical properties of proteins. By virtue of their importance, several PTM databases have been developed and released in decades, but very few of these databases incorporate real 3D structural data. Since PTMs influence the function of the protein and their aberrant states are frequently implicated in human diseases, providing structural insights to understand the influence and dynamics of PTMs is crucial for unraveling the underlying processes. This review is dedicated to the current status of databases providing 3D structural data on PTM sites in proteins. Some of these databases are general, covering multiple types of PTMs in different organisms, while others are specific to one particular type of PTM, class of proteins or organism. The importance of these databases is illustrated with two major types of in silico applications: predicting PTM sites in proteins using machine learning approaches and investigating protein structure-function relationships involving PTMs. Finally, these databases suffer from multiple problems and care must be taken when analyzing the PTMs data.

Secondary Structures of Proteins Follow Menzerath-Altmann Law.

This article examines the presence of the empirical tendency known as the Menzerath-Altmann Law (MAL) on protein secondary structures. MAL is related to optimization principles observed in natural languages and in genetic information on chromosomes or protein domains. The presence of MAL is examined on a non-redundant dataset of 4728 proteins by verifying significant, negative correlations and testing classical and newly proposed formulas by fitting the observed trend. We conclude that the lengths of secondary structures are specifically dependent on their number inside the protein sequence, while possibly reflecting the formula proposed in this paper. This behavior is observed on average but is individually avoidable and possibly driven by a latent cost function. The data suggest that MAL could provide a useful guiding principle in protein design.

Chemically characterizing the cortical cell nano-structure of human hair using atomic force microscopy integrated with infrared spectroscopy (AFM-IR).

OBJECTIVE: The use of conventional microscopy and vibrational spectroscopy in the optical region to investigate the chemical nature of hair fibres on a nanometre scale is frustrated by the diffraction limit of light, prohibiting the spectral elucidation of nanoscale sub-structures that contribute to the bulk properties of hair. The aim of this work was to overcome this limitation and gain unprecedented chemical resolution of cortical cell nano-structure of hair. METHODS: The hybrid technique of AFM-IR, combining atomic force microscopy with an IR laser, circumvents the diffraction limit of light and achieves nanoscale chemical resolution down to the AFM tip radius. In this work, AFM-IR was employed on ultra-thin microtomed cross-sections of human hair fibres to spectrally distinguish and characterize the specific protein structures and environments within the nanoscale components of cortical cells. RESULTS: At first, a topographical and chemical distinction between the macrofibrils and the surrounding intermacrofibillar matrix was achieved based on 2.5 × 2.5 µm maps of cortical cell cross-sections. It was found that the intermacrofibrillar matrix has a large protein content and specific cysteine-related residues, whereas the macrofibrils showed bigger contributions from aliphatic amino acid residues and acidic-/ester-containing species (e.g. lipids). Localized spectra recorded at a spatial resolution of the order of the AFM tip radius enabled the chemical composition of each region to be determined following deconvolution of the Amide-I and Amide-II bands. This provided specific evidence for a greater proportion of α-helices in the macrofibrils and correspondingly larger contributions of ß-sheet secondary structures in the intermacrofibrillar matrix, as inferred in earlier studies. Analysis of the parallel and antiparallel ß-sheet structures, and of selected dominant amino acid residues, yielded further novel composition and conformation results for both regions. CONCLUSION: In this work, we overcome the diffraction limit of light using atomic force microscopy integrated with IR laser spectroscopy (AFM-IR) to characterize sub-micron features of the hair cortex at ultra-high spatial resolution. The resulting spectral analysis shows clear distinctions in the Amide bands in the macrofibrils and surrounding intermacrofibrillar matrix, yielding novel insight into the molecular structure and intermolecular stabilization interactions of the constituent proteins within each cortical component.

OBJECTIF: L'utilisation de la microscopie conventionnelle et de la spectroscopie vibratoire dans la région optique pour étudier la nature chimique des fibres capillaires à l'échelle nanométrique est limitée par la limite de diffraction de la lumière, interdisant l'élucidation spectrale des sous-structures à l'échelle nanométrique qui contribuent aux propriétés des cheveux en général. L'objectif de ce travail était de surmonter cette limitation et d'obtenir une résolution chimique sans précédent de la nanostructure cellulaire corticale des cheveux. MÉTHODES: La technique hybride de l'AFM-IR, combinant la microscopie à force atomique avec un laser IR, contourne la limite de diffraction de la lumière et permet d'obtenir une résolution chimique à l'échelle nanométrique jusqu'au rayon de l'extrémité de l'AFM. Dans ce travail, l'AFM-IR a été employée sur des coupes transversales microtomes ultrafines de fibres de cheveux humains pour distinguer et caractériser sur le plan spectral les structures et environnements protéiques spécifiques au sein des composants à l'échelle nanométrique des cellules corticales. RÉSULTATS: Tout d'abord, une distinction topographique et chimique entre les macrofibrilles et la matrice intermacrofibrillaire environnante a été obtenue à partir de cartes de 2,5 × 2,5 micromètres des coupes transversales des cellules corticales. Il a été constaté que la matrice intermacrofibrillaire avait une grande teneur en protéines et des résidus spécifiques liés à la cystéine, tandis que les macrofibrilles présentaient des contributions plus importantes provenant de résidus d'acides aminés aliphatiques et d'espèces acides/contenant des esters (p. ex. lipides). Les spectres localisés enregistrés à une résolution spatiale de l'ordre du rayon de l'extrémité AFM ont permis de déterminer la composition chimique de chaque région suite à la déconvolution des bandes Amide-I et Amide-II. Cela a apporté des preuves spécifiques pour une plus grande proportion des hélices alpha des macrofibrilles, de même que des contributions plus importantes des structures secondaires à feuillet bêta dans la matrice intermacrofibrillaire, déduites dans des études antérieures. L'analyse des structures parallèles et antiparallèles des feuillets bêta, et des résidus d'acides aminés dominants sélectionnés a donné des résultats inédits de composition et de conformation pour les deux régions. CONCLUSION: Dans ce travail, nous avons surmonté la limite de diffraction de la lumière en utilisant la microscopie à force atomique intégrée à la spectroscopie laser IR (IR-AFM) pour caractériser les caractéristiques submicroniques du cortex capillaire à une résolution spatiale ultra-élevée. L'analyse spectrale qui en résulte montre des distinctions nettes dans les bandes d'amide dans les macrofibrilles et la matrice intermacrofibrillaire environnante, ce qui apporte un éclairage nouveau sur la structure moléculaire et les interactions de stabilisation intermoléculaire des protéines constitutives dans chaque composant cortical.