Biology subjects

Mokso, R.

Publications and source records attributed to Mokso, R..

6 recordsLinked to original sources

bioRxiv2025

Achieving Micrometer-Scale 4D X-ray tomography of Living Leaf Tissue in the Laboratory

A methodology for achieving micrometer-scale 4D X-ray lab microscopy of living leaf tissue was developed to overcome challenges associated with delicate tissues, radiation damage, and motion artifacts during in vivo imaging. The study focused on optimizing laboratory based X-ray micro-computed tomography (microCT) parameters to balance high-resolution imaging with minimized physiological stress and radiation dose quantification. Assessing the dose-safe imaging window required comparing vertical and horizontal leaf mounting setups. Results demonstrated that the horizontal setup provided greater stability, preventing tissue degradation and maintaining sample viability during continuous acquisitions lasting up to 22 hours ([~]15600 Gy). MicroCT capacities were clearly able to resolve microstructures at the cellular level, achieving a pixel size down to 1 {micro}m. Furthermore, this optimized methodology confirmed the ability to track the spatiotemporal dynamics of applied compounds such as iohexol and aggregated nanoparticles within the leaf tissue. This work establishes that accessible laboratory based microCT enables the in vivo 4D monitoring of anatomical and physiological changes in living plants.

plant biology↗

bioRxiv2025

Foliar Application of Polymer-coated Manganese Dioxide Nanoparticles: Mechanisms of Uptake and Metabolic Responses in Manganese Deficient Barley

The application of nanotechnology in plant science is unlocking innovative approaches to enhance nutrient use efficiency in crops, particularly through foliar fertilization. This study demonstrates that colloidally stable, pH-responsive polyacrylic acid (PAA)-coated manganese dioxide (MnO2) nanoparticles (nPAA-MnO2) can be designed to significantly restore key metabolic functionalities in manganese (Mn)-deficient barley (Hordeum vulgare) within a few days. Using a combination of advanced bioimaging techniques - including confocal laser scanning microscopy (CLSM), laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), and X-ray nano-computed tomography (nano-CT), we mapped the uptake and distribution pathways of nPAA-MnO2 compared to ionic Mn. While soluble Mn2+ ions primarily enter through hydrophilic cuticular pores, nPAA-MnO2 penetrates leaves via stomata, facilitated by the application of an organosilicone surfactant and glycerol to enhance wetting and hydraulic activation of stomatal pores. Within a few hours, nPAA-MnO2 accumulated in the sub-stomatal cavity and mesophyll apoplast, gradually releasing bioavailable Mn ions in the acidic apoplast environment. Moreover, labeling experiments with tracer ions revealed nPAA-MnO2 hot-spots around the vascular bundles and a limited but significant basipetal translocation of intact nanoparticles out of the foliar application zone, a pivotal step towards converting immobile nutrients such as Mn into mobile ones. Importantly, and unlike ionic Mn solutions, nPAA-MnO2 could be applied at high doses without causing leaf scorching and cytotoxicity, paving the way for more sustainable and efficient foliar fertilization practices. These novel aspects of nanoparticle uptake, translocation, and assimilation underscores the potential of nanotechnology to address nutrient mobility challenges in agriculture, representing an important contribution to the green transition of modern crop production.

plant biology↗

bioRxiv2025

3D X-ray microscopy lights up nanoparticles in plants

The discovery of novel plant fertilization strategies heavily relies on our capabilities to probe physiological processes in living plants with sub-cellular precision. State-of-the-art microscopy techniques are in general limited to surface investigation or they require elaborated tissue preparation and often destruction. X-ray microscopy has the potential to resolve some of these limitations by generating micro-to nanometer-scale 3D images deep into the tissue. We introduce experimental designs and the quantitative analysis methodologies, pioneering nanoscale ({approx}150 nm resolution) in-vivo 3D microscopy of plant tissue. We show the first direct in-vivo visualization of foliar-applied untagged nanoparticulate fertilizers deep under the leaf surface, not accessible by other microscopy methods. Ultimately, our approach provides the means for a direct observation of nanoparticle transport and dissolution in living plant tissue, a step critical for developing sustainable plant fertilization approaches.

plant biology↗

bioRxiv2023

A Practical Approach to Estimating the Effect of Synchrotron Radiation on Sperm Motility and Viability

Studying the dynamics of sperm tail beating in 3D is important for understanding decreasing fertility trends related to motility. Syn-chrotron X-ray tomography (SXRT) shows promising results for imaging live biological samples in 3D and time, making it a candidate for imaging sperm tail beating patterns. However, the dose of ionizing radiation (IR) that the cells would receive during image acquisition is of concern as this is likely to affect essential cellular functions. The effect of IR on motility at the dose rates encountered in a synchrotron has never been assessed. Here, results are presented of analyzing the movement and viability of sperm cells exposed at varying durations at the TOMCAT beamline (Swiss Light Source (SLS)) which has the field of view and spatial resolution needed to reconstruct sperm cells coupled with sub-second exposure times. The results indicate that motility is affected long before viability and that sperm cell dynamics are affected very quickly by the beam.

biophysics↗

bioRxiv2022

Astrocytic engagement of the corticostriatal synaptic cleft is disrupted in a mouse model of Huntington disease

Astroglial dysfunction contributes to the pathogenesis of Huntingtons disease (HD), and glial replacement can ameliorate disease course. To establish the topographic relationship of diseased astrocytes to medium spiny neuron (MSN) synapses in HD, we used 2-photon imaging to map the relationship of tRFP-tagged striatal astrocytes and rabies-traced, EGFP-tagged coupled neuronal pairs, in R6/2 HD and wild-type (WT) mice. The tagged, prospectively-identified corticostriatal synapses were then studied by correlated light electron microscopy followed by serial block-face scanning EM, allowing nm scale assessment of synaptic structure in 3D. By this means, we compared the astrocytic engagement of single striatal synapses in HD and WT brains. R6/2 HD astrocytes exhibited constricted domains, with significantly less coverage of mature dendritic spines than WT astrocytes, despite enhanced engagement of immature, thin spines. These data suggest that disease-dependent changes in astroglial engagement and sequestration of MSN synapses enable the high synaptic and extrasynaptic levels of glutamate and K+ that underlie the striatal hyperexcitability of HD. As such, these data suggest that astrocytic structural pathology may causally contribute to the synaptic dysfunction and disease phenotype of those neurodegenerative disorders characterized by network overexcitation. Significance StatementAstrocytic physiological dysfunction contributes to development of the neurodegenerative phenotype in Huntingtons disease (HD), but the structural correlates to this dysfunction are unclear. Here, we used a combination of viral tracing, phenotype-specific tagging, and ultrastructural modalities to reconstruct and study HD synapses at nm scale, in the neostriata of HD mice. We discovered significant impairment in the glial engagement of mature striatal synapses. In light of the known deficiencies in glutamate and potassium uptake by HD astrocytes, these findings suggest the potential for leakage of excitatory synaptic contents during neurotransmission, and hance a structural basis for neuronal hyperexcitability in HD. More broadly, our data suggest that astrocytic structural pathology may causally contribute to those neurodegenerative disorders associated with central hyperexcitability.

neuroscience↗

bioRxiv2021

Binocular Mirror-Symmetric Microsaccadic Sampling of Hyperacute 3D-Vision

Neural mechanisms behind stereopsis, which requires simultaneous disparity inputs from two eyes, have remained mysterious. Here we show how ultrafast mirror-symmetric photomechanical contractions in the frontal forward-facing left and right eye photoreceptors give Drosophila super-resolution 3D-vision. By interlinking multiscale in vivo assays with multiscale simulations, we reveal how these photoreceptor microsaccades - by verging, diverging and narrowing the eyes overlapping receptive fields - channel depth information, as phasic binocular image motion disparity signals in time. We further show how peripherally, outside stereopsis, microsaccadic sampling tracks a flying flys optic flow field to better resolve the world in motion. These results change our understanding of how insect compound eyes work and suggest a general dynamic stereo-information sampling strategy for animals, robots and sensors. Significance statementTo move efficiently, animals must continuously work out their x,y,z-positions in respect to real-world objects, and many animals have a pair of eyes to achieve this. How photoreceptors actively sample the eyes optical image disparity is not understood because this fundamental information-limiting step has not been investigated in vivo over the eyes whole sampling matrix. This integrative multiscale study will advance our current understanding of stereopsis from static image disparity comparison to a new morphodynamic active sampling theory. It shows how photomechanical photoreceptor microsaccades enable Drosophila super-resolution 3D-vision and proposes neural computations for accurately predicting these flies depth-perception dynamics, limits, and visual behaviors.

neuroscience↗