Biology subjects

Prevedel, R.

Publications and source records attributed to Prevedel, R..

30 records · Page 2Linked to original sources

bioRxiv2021

Ethology of morphogenesis reveals the design principles of cnidarian size and shape development

During development, organisms interact with their natural habitats while undergoing morphological changes, yet it remains unclear whether the interplay between developing systems and their environments impacts animal morphogenesis. Here, we use the cnidarian Nematostella vectensis as a developmental model to uncover a mechanistic link between organism size, shape and behavior. Using quantitative live imaging, including extensive behavioral profiling, combined with molecular and biophysical experiments, we demonstrate that the muscular hydraulic machinery that controls body movement directly drives larva-polyp morphogenesis. Unexpectedly, size and shape development are differentially controlled by antagonistic muscles. A simple theoretical model shows how a combination of slow-priming and fast-pumping pressures generated by muscular hydraulics acts as a global mechanical regulator that coordinates tissue remodeling. Altogether, our findings illuminate how dynamic behavioral modes in the environment can be harnessed to drive morphogenetic trajectories, establishing ethology as a critical component of organismal morphogenesis - termed ethology of morphogenesis.

developmental biology↗

bioRxiv2021

Mechanical mapping of mammalian follicle development using Brillouin microscopy

In early mammalian development, the maturation of follicles containing the immature oocytes is an important biological process as the functional oocytes provide the bulk genetic and cytoplasmic materials for successful reproduction. Despite recent work demonstrating the regulatory role of mechanical stress in oocyte growth, quantitative studies of ovarian mechanical properties remain lacking both in vivo and ex vivo. In this work, we quantify the material properties of ooplasm, follicles and connective tissues in intact mouse ovaries at distinct stages of follicle development using Brillouin microscopy, a non-invasive tool to probe mechanics in three-dimensional (3D) tissues. We find that the ovarian cortex and its interior stroma have distinct material properties associated with extracellular matrix deposition, and that intra-follicular mechanical compartments emerge during follicle maturation. Our work provides a novel approach to study the role of mechanics in follicle morphogenesis and pave the way for future understanding of mechanotransduction in reproductive biology, with potential implications for infertility diagnosis and treatment.

biophysics↗

bioRxiv2021

Primary motor cortex activity traces distinct trajectories of population dynamics during spontaneous facial motor sequences in mice

We explore the link between on-going neuronal activity at primary motor cortex (M1) and face movement in awake mice. By combining custom-made behavioral sequencing analysis and fast volumetric Ca2+-imaging, we simultaneously tracked M1 population activity during many different facial motor sequences. We show that a facial area of M1 displays distinct trajectories of neuronal population dynamics across different spontaneous facial motor sequences, suggesting an underlying population dynamics code. Significance statementHow our brain controls a seemingly limitless diversity of body movements remains largely unknown. Recent research brings new light into this subject by showing that neuronal populations at the primary motor cortex display different dynamics during forelimb reaching movements versus grasping, which suggests that different motor sequences could be associated with distinct motor cortex population dynamics. To explore this possibility, we designed an experimental paradigm for simultaneously tracking the activity of neuronal populations in motor cortex across many different motor sequences. Our results support the concept that distinct population dynamics encode different motor sequences, bringing new insight into the role of motor cortex in sculpting behavior while opening new avenues for future research.

neuroscience↗

bioRxiv2021

Adaptive optics enhanced all-optical photoacoustic tomography

All-optical ultrasound detection bears a number of unique advantages for photoacoustic tomography, including the ability for high resolution sampling of the acoustic field and its compatibility with a wide variety of other optical modalities. However, optical schemes based on miniaturized cavities are sensitive to optical aberrations as well as manufacturing-induced cavity imperfections which degrade sensor sensitivity and deteriorate photoacoustic image quality. Here we present an experimental method based on adaptive optics that is capable of enhancing the overall sensitivity of Fabry-Perot based photoacoustic sensors. We experimentally observe clear improvements in photoacoustic signal detection as well as overall image quality after photoacoustic tomography reconstructions when applied to mammalian tissues in vivo.

bioengineering↗

bioRxiv2021

High-resolution structural and functional deep brain imaging using adaptive optics three-photon microscopy

Multi-photon microscopy has become a powerful tool to visualize the morphology and function of neural cells and circuits in the intact mammalian brain. Yet, tissue scattering, optical aberrations, and motion artifacts degrade the achievable image quality with depth. Here we developed a minimally invasive intravital imaging methodology by combining three-photon excitation, indirect adaptive optics correction, and active electrocardiogram gating to achieve near-diffraction limited resolution up to a depth of 1.2mm in the mouse brain. We demonstrate near-diffraction-limited imaging of deep cortical and sub-cortical dendrites and spines as well as of calcium transients in deep-layer astrocytes in vivo.

bioengineering↗

bioRxiv2020

AIE-nanoparticle assisted ultra-deep microscopy in the in vivo mouse brain under 1300-nm excitation

Aggregation-induced emission nanoparticles serve as promising fluorescence probes for multi-photon excitation microscopy due to the large absorption cross-section at NIR-IIb region. Here we present organic AIE nanoparticles that feature high aborption cross-section under three-photon excitation. We show that these enable ultra-deep NIR-IIa excited three-photon imaging in the in-vivo mouse brain.

neuroscience↗

bioRxiv2020

In-vivo monitoring and quantification of breast cancer growth dynamics with non-invasive intravital mesoscopic fluorescence molecular tomography

Preclinical breast tumor models are an invaluable tool to systematically study tumor progression and treatment response, yet methods to non-invasively monitor the involved molecular and mechanistic properties under physiologically relevant conditions are limited. Here we present an intravital mesoscopic fluorescence molecular tomography (henceforth IFT) approach that is capable of tracking fluorescently labeled tumor cells in a quantitative manner inside the mammary gland of living mice. Our mesoscopic approach is entirely non-invasive and thus permits prolonged observational periods of several months. The relatively high sensitivity and spatial resolution further enable inferring the overall number of oncogene-expressing tumor cells as well as their tumor volume over the entire cycle from early tumor growth to residual disease following the treatment phase. We find that sheer tumor volume, as commonly assessed by other imaging modalities, is not well correlated to tumor cell quantity, hence our IFT approach is a promising new method for studying tumor growth dynamics in a quantitative and longitudinal fashion in-vivo.

bioengineering↗

bioRxiv2020

Deep learning-enhanced light-field imaging with continuous validation

Light-field microscopy (LFM) has emerged as a powerful tool for fast volumetric image acquisition in biology, but its effective throughput and widespread use has been hampered by a computationally demanding and artefact-prone image reconstruction process. Here, we present a novel framework consisting of a hybrid light-field light-sheet microscope and deep learning-based volume reconstruction, where single light-sheet acquisitions continuously serve as training data and validation for the convolutional neural network reconstructing the LFM volume. Our network delivers high-quality reconstructions at video-rate throughput and we demonstrate the capabilities of our approach by imaging medaka heart dynamics and zebrafish neural activity.

bioengineering↗

bioRxiv2020

Identification of a novel population of peripheral sensory neuron that regulates blood pressure

The vasculature is innervated by a network of peripheral afferents that sense and regulate blood flow. Here, we describe a system of non-peptidergic sensory neurons with cell bodies in the spinal ganglia that regulate vascular tone in the distal arteries. We identify a population of mechanosensitive neurons marked by TrkC and Tyrosine hydroxylase in the dorsal root ganglia that project to blood vessels. Local stimulation of these neurons decreases vessel diameter and blood flow, while systemic activation increases systolic blood pressure and heart rate variability via the sympathetic nervous system. Chemogenetic inactivation or ablation of the neurons provokes variability in local blood flow leading to a reduction in systolic blood pressure, increased heart rate variability and ultimately lethality within 48 hours. Thus, TrkC/Tyrosine hydroxylase positive sensory neurons form part of a sensory feedback mechanism that maintains cardiovascular homeostasis through the autonomic nervous system.

neuroscience↗

bioRxiv2018

Imaging mechanical properties of sub-micron ECM in live zebrafish using Brillouin microscopy

In this work, we quantify the mechanical properties of extra-cellular matrix (ECM) in live zebrafish using Brillouin microscopy. Optimization of the imaging conditions and parameters, combined with careful spectral analysis, allows us to resolve the thin ECM and distinguish its Brillouin frequency shift from the surrounding tissue. High-resolution mechanical mapping further enables to directly measure the thickness of the ECM label-free and in-vivo. We find the ECM to be ~400nm thick, in excellent agreement with electron microscopy quantification. Our results open the door for future studies that aim to investigate the role of ECM mechanics for zebrafish morphogenesis and axis elongation.

bioengineering↗

bioRxiv2018

Instantaneous isotropic volumetric imaging of fast biological processes

Capturing highly dynamic biological processes at sub-cellular resolution is a recurring challenge in biology. Here we show that combining selective volume illumination with simultaneous acquisition of orthogonal light-fields yields 3D images with high, isotropic spatial resolution and free of reconstruction artefacts, thereby overcoming current limitations of light-field microscopy implementations. We demonstrate Medaka heart and blood flow imaging with single-cell resolution and free of motion artefacts at volume rates up to 200Hz.

bioengineering↗

bioRxiv2017

Quantitative evaluation of two-photon calcium imaging modalities for high-speed volumetric calcium imaging in scattering brain tissue

Considerable efforts are currently being devoted to enhance the speed, spatial resolution and the size of the 3D sample volumes in which calcium imaging methods can capture neuronal network activity in different model systems. In the mammalian brain, tissue scattering severely limits the use of parallel acquisition techniques such as wide-field imaging and, as a consequence, methods based on two-photon point-scanning (2PM) have become the method of choice. However, 2PM faces severe restrictions due to technical limitations such as scan speed, laser power, and those related to the fluorescent probes, calling for conceptually new approaches to enhance the performance of two-photon calcium imaging schemes. Here we provide a detailed quantitative evaluation and comparison of different excitation/detection modalities from the perspective of detecting neuronal activity that are based on different point-spread functions (PSF), laser repetition rates and sampling strategies. We demonstrate the conditions for which imaging speed and signal-to-noise ratio are optimized for a given average power. Our results are based on numerical simulations which are informed by experimentally measured parameters and show that volumetric field of view and acquisition speed can be considerably improved compared to traditional 2PM schemes by a holistic optimization approach.

neuroscience↗