Biology subjects

Chiaruttini, N.

Publications and source records attributed to Chiaruttini, N..

6 recordsLinked to original sources

bioRxiv2024

ABBA, a novel tool for whole-brain mapping, reveals brain-wide differences in immediate early genes induction following learning

Unbiased characterization of whole-brain cytoarchitecture represents an invaluable tool for understanding brain function. For this, precise mapping of histological markers from 2D sections onto 3D brain atlases is pivotal. Here, we present two novel software tools facilitating this process: Aligning Big Brains and Atlases (ABBA), designed to streamline the precise and efficient registration of 2D sections to 3D reference atlases, and BraiAn, an integrated suite for multi-marker automated segmentation, whole-brain statistical analysis, and data visualisation. Combining these tools, we performed a comprehensive comparative study of the whole-brain expression of three of the most widely used immediate early genes (IEGs). Thanks to their neural activity-dependent expression, IEGs have been used for decades as a proxy of neural activity to generate unbiased mapping of activity following behaviour, but their respective induction in response to neuronal activation across the entire brain remains unclear. To address this question, we systematically compared the brain-wide expression cFos, Arc and NPAS4, three abundantly used IEGs, across three different behavioural conditions related to memory. Our results highlight major differences in both their distribution and induction patterns, indicating that they do not represent equivalent markers across brain areas or activity states, but can provide instead complementary information.

neuroscience↗

bioRxiv2024

A multicellular developmental program in a close animal relative

All animals develop from a single-celled zygote into a complex multicellular organism through a series of precisely orchestrated processes. Despite the remarkable conservation of early embryogenesis across animals, the evolutionary origins of this process remain elusive. By combining time-resolved imaging and transcriptomic profiling, we show that single cells of the ichthyosporean Chromosphaera perkinsii - a close relative that diverged from animals approximately 1 billion years ago - undergo symmetry breaking and develop through cleavage divisions to produce a prolonged multicellular colony with distinct co-existing cell types. Our findings about the autonomous developmental program of C. perkinsii, hint that such animal-like multicellular development is either much older than previously thought or evolved convergently in ichthyosporeans. One-Sentence SummaryThe ichthyosporean C. perkinsii develops via symmetry breaking, cleavage divisions, and forms spatially-organized colonies with distinct cell types.

developmental biology↗

bioRxiv2023

Clock driven waves of Tbx6 expression prefigure somite boundaries

The segmented body plan of vertebrates is established during embryogenesis by periodic and sequential formation of multi-cellular structures called somites. Somitogenesis is an example of patterning by a biological oscillator, the segmentation clock, which manifests as traveling waves of oscillating Hes/Her gene expression, reiterating during the formation of each1-3. How these waves are converted into the striped Mesp gene expression pattern that prefigures morphological somite boundaries4-8 remains unclear. Here, we image this conversion in real-time at single-cell resolution in zebrafish, using light-sheet microscopy of a novel reporter of Tbx6, a key activator of Mesp expression. We observe cellular oscillations and kinematic waves of Tbx6 expression that are driven by Hes/Her genes. Tbx6 waves arrest precisely in boundary cells that eventually express Mesp, thereby prefiguring the Mesp pattern, whereas Hes/Her waves do not. Although Hes/Her oscillations began before somitogenesis9-11, the first Tbx6 wave defines the boundary cells of the anterior-most somite, forming the head-trunk interface. Our findings imply that Tbx6 acts as a genetic clutch, converting Her/Hes pacemaker waves into Mesp stripes. We propose that this clock design shields the pacemaker from external perturbations, allowing flexible and robust patterning, making it of interest for organoids and tissue-engineering.

developmental biology↗

bioRxiv2023

But, what are the cells doing? Image Analysis pipeline to follow single cells in the zebrafish embryo

Microscopy has rapidly evolved at pace with live markers, enabling ever higher spatiotemporal resolution of multicellular dynamics within larger fields of view. Consequently, we are now in the era of widespread production of terabyte (TB)-sized time-lapse movies of experimental model systems, including developing embryos and organoids. Working with these large datasets has presented a new set of hurdles, particularly due to the lack of standardized open-source pipelines for acquiring, handling and analyzing the data. Moreover, although long-term tracking of a cell throughout an entire process, for example vertebrate organogenesis, is key to revealing the underlying cellular dynamics, this has proven largely elusive. To specifically address the question "But, what are the cells doing?", we created an image analysis pipeline optimized to track single cells in light-sheet acquired datasets (1 TB sized time-lapse, 8h of imaging, 30 min gene expression cycle, cell movement speed (1{micro}m /1 minute), 200-400 {micro}m tissue depth). Our modular pipeline optimizes and connects the following: image acquisition parameters to improve tracking feasibility; hardware specifications; data handling and compression tools; pre-processing steps; state-of-the-art cell tracking tools (Mastodon, MaMuT) and a novel open-source/ python-based tool (Paleontologist) to analyze and visualize spatiotemporal dynamics of the tracked cells. Importantly, our pipeline is adaptable to a variety of experimental systems and accessible to researchers regardless of expertise in coding and image analysis. One-sentence SummaryUser-friendly cell-tracking pipeline that connects image acquisition in multicellular systems through to data analysis of cellular dynamics.

developmental biology↗

bioRxiv2022

MoBIE: A Fiji plugin for sharing and exploration of multi-modal cloud-hosted big image data

Facing the challenge of exploring and sharing multi-terabyte, multi-modal and multi-scale image data of heterogeneous dimensionality, we developed MoBIE, a Fiji plugin that provides rich visualization features to enable browsing data from numerous biomedical applications on a standard laptop computer. MoBIE also supports segmentations, associated measurements and annotations. Users can configure complex views of datasets, share them with collaborators, and use them for interactive figure panels. The MoBIE plugin also offers a convenient interface for converting data into compatible data formats; an additional Python library facilitates managing diverse MoBIE projects.

bioinformatics↗

bioRxiv2018

LimeSeg: A coarsed-grained lipid membrane simulation for 3D image segmentation

Bioimage analysis is an important preliminary step required for data representation and quantitative studies. To carry out these tasks, we developed LimeSeg, an easy-to-use, efficient and modular 3D image segmentation method. Based on the idea of SURFace ELements, LimeSeg resembles a highly coarse-grained simulation of a lipid membrane in which a set of particles, analogous to lipid molecules, are attracted to local image maxima. The particles are self-generating and self-destructing thus providing the ability for the membrane to evolve towards the contour of the object of interest. We characterize the emergent mechanical properties of this system and show how it can be used to segment many 3D objects from numerous types of image of biological samples (brain MRI, cell epithelium, cellular organelles). LimeSeg is available as a Fiji plugin that includes simple commands, a 3D visualizer, and customization options via ImageJ scripting.

bioinformatics↗