Microtubule dynamics depart from wormlike chain model

Thermal shape fluctuations of grafted microtubules were studied using high resolution particle tracking of attached fluorescent beads. First mode relaxation times were extracted from the mean square displacement in the transverse coordinate. For microtubules shorter than 10 um, the relaxation times were found to follow an L^2 dependence instead of L^4 as expected from the standard wormlike chain model. This length dependence is shown to result from a complex length dependence of the bending stiffness which can be understood as a result of the molecular architecture of microtubules. For microtubules shorter than 5 um, high drag coefficients indicate contributions from internal friction to the fluctuation dynamics.Comment: 4 pages, 4 figures. Updated content, added reference, corrected typo

Metal N,N-dialkylcarbamates as easily available catalytic precursors for the carbon dioxide/propylene oxide coupling under ambient conditions

A series of previously reported homoleptic and non-homoleptic N,N-dialkylcarbamates of a range of non precious metals and N,N-dialkylcarbamate of Al(III) were investigated as easily available and inexpensive catalysts in the solventless synthesis of propylene carbonate (PC) from propylene oxide (PO) and CO2. By operating at atmospheric CO2 pressure at ambient temperature, excellent results were achieved using Ti(O2CNEt2)4, Al(O2CNR2)3 (R = Et, iPr), Cu(O2CNEt2)2 and Sn(O2CNEt2)4, in combination with NBu4X (X = Br or Cl) as a co-catalyst. The reactions of MCl2(O2CNEt2)2 (M = Ti, Zr) with amorphous silica were straightforward through partial release of both chlorido and carbamato ligands, and readily afforded solid materials which were characterized by ICP-OES and EDS analyses, coupled to SEM. These heterogeneous catalytic systems revealed less efficient than the homogeneous counterparts

3D-Cell-Annotator : an open-source active surface tool for single-cell segmentation in 3D microscopy images

aSummary: Segmentation of single cells in microscopy images is one of the major challenges in computational biology. It is the first step of most bioimage analysis tasks, and essential to create training sets for more advanced deep learning approaches. Here, we propose 3D-Cell-Annotator to solve this task using 3D active surfaces together with shape descriptors as prior information in a semi-automated fashion. The software uses the convenient 3D interface of the widely used Medical Imaging Interaction Toolkit (MITK). Results on 3D biological structures (e.g. spheroids, organoids and embryos) show that the precision of the segmentation reaches the level of a human expert.Peer reviewe

Light Sheet-Based Laser Patterning Bioprinting Produces Long-Term Viable Full-Thickness Skin Constructs

Tissue engineering holds great promise for biomedical research and healthcare, offering alternatives to animal models and enabling tissue regeneration and organ transplantation. 3D bioprinting stands out for its design flexibility and reproducibility. Here, an integrated fluorescent light sheet bioprinting and imaging system is presented that combines high printing speed (0.66 mm3/s) and resolution (9 µm) with light sheet-based imaging. This approach employs direct laser patterning and a static light sheet for confined voxel crosslinking in photocrosslinkable materials. The developed bioprinter enables real-time monitoring of hydrogel crosslinking using fluorescent recovery after photobleaching (FRAP) and brightfield imaging as well as in situ light sheet imaging of cells. Human fibroblasts encapsulated in a thiol-ene click chemistry-based hydrogel exhibited high viability (83% ± 4.34%) and functionality. Furthermore, full-thickness skin constructs displayed characteristics of both epidermal and dermal layers and remained viable for 41 days. The integrated approach demonstrates the capabilities of light sheet bioprinting, offering high speed, resolution, and real-time characterization. Future enhancements involving solid-state laser scanning devices such as acousto-optic deflectors and modulators will further enhance resolution and speed, opening new opportunities in light-based bioprinting and advancing tissue engineering

Rubens' painting as inspiration of a later tapestry: non-invasive analyses provide insight into artworks history.

The 17th century painting Madonna della Cesta by Rubens and its presumed textile reproduction created by Févère for the House of Medici were analysed in comparison. A number of non-invasive optical techniques were applied with the aim to identify similarities and differences between tapestry and painting, in order to shed light on a possible link between their respective authors. The use of a multi-analytical approach proved effective for the acquisition of iconographic, morphological, structural, and compositional information for a comprehensive characterization of the two artworks. While serving as relevant support for documentation and conservation purposes, data so obtained also provide evidence of the uncanny resemblance between the two artworks, and specifically suggest the use by Févère of the same large-scale preparatory drawing (carton) realized by Rubens for his oil painting.Fil: Dal Fovo, Alicia. No especifíca;Fil: Striova, Jana. No especifíca;Fil: Pampaloni, Enrico. No especifíca;Fil: Fedeli, Ana María. Università della Calabria; ItaliaFil: Morita, María Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; ArgentinaFil: Amaya Robayo, Dafne Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; ArgentinaFil: Grazzi, Francesco. Centre National de la Recherche Scientifique; FranciaFil: Cimò, Marta. No especifíca;Fil: Cirrincione, Claudia. No especifíca;Fil: Fontana, Raffaella. No especifíca

AMP-Activated Protein Kinase alpha 2 in Neutrophils Regulates Vascular Repair via Hypoxia-Inducible Factor-1 alpha and a Network of Proteins Affecting Metabolism and Apoptosis

Rationale: The AMP-activated protein kinase (AMPK) is stimulated by hypoxia, and although the AMPK alpha 1 catalytic subunit has been implicated in angiogenesis, little is known about the role played by the AMPK alpha 2 subunit in vascular repair. Objective: To determine the role of the AMPK alpha 2 subunit in vascular repair. Methods and Results: Recovery of blood flow after femoral artery ligation was impaired (>80%) in AMPK alpha 2(-/-) versus wild-type mice, a phenotype reproduced in mice lacking AMPK alpha 2 in myeloid cells (AMPK alpha 2(Delta MC)). Three days after ligation, neutrophil infiltration into ischemic limbs of AMPK alpha 2(Delta MC) mice was lower than that in wild-type mice despite being higher after 24 hours. Neutrophil survival in ischemic tissue is required to attract monocytes that contribute to the angiogenic response. Indeed, apoptosis was increased in hypoxic neutrophils from AMPK alpha 2(Delta MC) mice, fewer monocytes were recruited, and gene array analysis revealed attenuated expression of proangiogenic proteins in ischemic AMPK alpha 2(Delta MC) hindlimbs. Many angiogenic growth factors are regulated by hypoxia-inducible factor, and hypoxia-inducible factor-1 alpha induction was attenuated in AMPK alpha 2-deficient cells and accompanied by its enhanced hydroxylation. Also, fewer proteins were regulated by hypoxia in neutrophils from AMPK alpha 2(Delta MC) mice. Mechanistically, isocitrate dehydrogenase expression and the production of alpha-ketoglutarate, which negatively regulate hypoxia-inducible factor-1 alpha stability, were attenuated in neutrophils from wild-type mice but remained elevated in cells from AMPK alpha 2(Delta MC) mice. Conclusions: AMPK alpha 2 regulates alpha-ketoglutarate generation, hypoxia-inducible factor-1 alpha stability, and neutrophil survival, which in turn determine further myeloid cell recruitment and repair potential. The activation of AMPK alpha 2 in neutrophils is a decisive event in the initiation of vascular repair after ischemia

Exploiting the ANN Potential in Estimating Snow Depth and Snow Water Equivalent From the Airborne SnowSAR Data at X- and Ku-Bands

Within the framework of European Space Agency (ESA) activities, several campaigns were carried out in the last decade with the purpose of exploiting the capabilities of multifrequency synthetic aperture radar (SAR) data to retrieve snow information. This article presents the results obtained from the ESA SnowSAR airborne campaigns, carried out between 2011 and 2013 on boreal forest, tundra and alpine environments, selected as representative of different snow regimes. The aim of this study was to assess the capability of X- and Ku-bands SAR in retrieving the snow parameters, namely snow depth (SD) and snow water equivalent (SWE). The retrieval was based on machine learning (ML) techniques and, in particular, of artificial neural networks (ANNs). ANNs have been selected among other ML approaches since they are capable to offer a good compromise between retrieval accuracy and computational cost. Two approaches were evaluated, the first based on the experimental data (data driven) and the second based on data simulated by the dense medium radiative transfer (DMRT). The data driven algorithm was trained on half of the SnowSAR dataset and validated on the remaining half. The validation resulted in a correlation coefficient R ≃ 0.77 between estimated and target SD, a root-mean-square error (RMSE) ≃ 13 cm, and bias = 0.03 cm. ANN algorithms specific for each test site were also implemented, obtaining more accurate results, and the robustness of the data driven approach was evaluated over time and space. The algorithm trained with DMRT simulations and tested on the experimental dataset was able to estimate the target parameter (SWE in this case) with R = 0.74, RMSE = 34.8 mm, and bias = 1.8 mm. The model driven approach had the twofold advantage of reducing the amount of in situ data required for training the algorithm and of extending the algorithm exportability to other test sites

Microneurography as a tool to develop decoding algorithms for peripheral neuro-controlled hand prostheses

The usability of dexterous hand prostheses is still hampered by the lack of natural and effective control strategies. A decoding strategy based on the processing of descending efferent neural signals recorded using peripheral neural interfaces could be a solution to such limitation. Unfortunately, this choice is still restrained by the reduced knowledge of the dynamics of human efferent signals recorded from the nerves and associated to hand movements.Findings: To address this issue, in this work we acquired neural efferent activities from healthy subjects performing hand- related tasks using ultrasound-guided microneurography, a minimally invasive technique, which employs needles, inserted percutaneously, to record from nerve fibers. These signals allowed us to identify neural features correlated with force and velocity of finger movements that were used to decode motor intentions. We developed computational models, which confirmed the potential translatability of these results showing how these neural features hold in absence of feedback and when implantable intrafascicular recording, rather than microneurography, is performed.Conclusions: Our results are a proof of principle that microneurography could be used as a useful tool to assist the development of more effective hand prostheses

Ultra-thin fluorocarbon foils optimise multiscale imaging of three-dimensional native and optically cleared specimens

In three-dimensional light microscopy, the heterogeneity of the optical density in a specimen ultimately limits the achievable penetration depth and hence the three-dimensional resolution. The most direct approach to reduce aberrations, improve the contrast and achieve an optimal resolution is to minimise the impact of changes of the refractive index along an optical path. Many implementations of light sheet fluorescence microscopy operate with a large chamber filled with an aqueous immersion medium and a further inner container with the specimen embedded in a possibly entirely different non-aqueous medium. In order to minimise the impact of the latter on the optical quality of the images, we use multi-facetted cuvettes fabricated from vacuum-formed ultra-thin fluorocarbon (FEP) foils. The ultra-thin FEP-foil cuvettes have a wall thickness of about 10–12 µm. They are impermeable to liquids, but not to gases, inert, durable, mechanically stable and flexible. Importantly, the usually fragile specimen can remain in the same cuvette from seeding to fixation, clearing and observation, without the need to remove or remount it during any of these steps. We confirm the improved imaging performance of ultra-thin FEP-foil cuvettes with excellent quality images of whole organs such us mouse oocytes, of thick tissue sections from mouse brain and kidney as well as of dense pancreas and liver organoid clusters. Our ultra-thin FEP-foil cuvettes outperform many other sample-mounting techniques in terms of a full separation of the specimen from the immersion medium, compatibility with aqueous and organic clearing media, quick specimen mounting without hydrogel embedding and their applicability for multiple-view imaging and automated image segmentation. Addit

Ultra-thin fluorocarbon foils optimise multiscale imaging of three-dimensional native and optically cleared specimens

In three-dimensional light microscopy, the heterogeneity of the optical density in a specimen ultimately limits the achievable penetration depth and hence the three-dimensional resolution. The most direct approach to reduce aberrations, improve the contrast and achieve an optimal resolution is to minimise the impact of changes of the refractive index along an optical path. Many implementations of light sheet fluorescence microscopy operate with a large chamber filled with an aqueous immersion medium and a further inner container with the specimen embedded in a possibly entirely different non-aqueous medium. In order to minimise the impact of the latter on the optical quality of the images, we use multi-facetted cuvettes fabricated from vacuum-formed ultra-thin fluorocarbon (FEP) foils. The ultra-thin FEP-foil cuvettes have a wall thickness of about 10–12 µm. They are impermeable to liquids, but not to gases, inert, durable, mechanically stable and flexible. Importantly, the usually fragile specimen can remain in the same cuvette from seeding to fixation, clearing and observation, without the need to remove or remount it during any of these steps. We confirm the improved imaging performance of ultra-thin FEP-foil cuvettes with excellent quality images of whole organs such us mouse oocytes, of thick tissue sections from mouse brain and kidney as well as of dense pancreas and liver organoid clusters. Our ultra-thin FEP-foil cuvettes outperform many other sample-mounting techniques in terms of a full separation of the specimen from the immersion medium, compatibility with aqueous and organic clearing media, quick specimen mounting without hydrogel embedding and their applicability for multiple-view imaging and automated image segmentation. Addit