Biology subjects

Bastide, S.

Publications and source records attributed to Bastide, S..

5 recordsLinked to original sources

bioRxiv2022

Fast reoptimization of human motor patterns in non-Earth gravity fields locally induced by a robotic exoskeleton

Gravity is a ubiquitous component of our environment that we learnt to optimally integrate in movement control. Yet, altered gravity conditions arise in numerous applications from space exploration to rehabilitation, thereby pressing the sensorimotor system to adapt. Here, we used a robotic exoskeleton to test whether humans can quickly reoptimize their motor patterns in arbitrary gravity fields, ranging from 1g to -1g and passing through Mars- and Moon-like gravities. By comparing the motor patterns of actual arm movements with those predicted by an optimal control model, we show that our participants (N = 61) quickly and optimally adapted their motor patterns to each local gravity condition. These findings show that arbitrary gravity-like fields can be efficiently apprehended by humans, thus opening new perspectives in arm weight support training in manipulation tasks, whether it be for patients or astronauts.

neuroscience↗

bioRxiv2022

TATTOO-seq delineates spatial and cell type-specific regulatory programs during limb patterning

The coordinated differentiation of progenitor cells into specialized cell types and their spatial organization into distinct domains is central to embryogenesis. Here, we applied a new unbiased spatially resolved single-cell transcriptomics method to identify the genetic programs that underlie the emergence of specialized cell types during limb development and their integration in space. We uncovered combinations of transcription factors whose expression patterns are predominantly associated with cell type specification or spatial position, enabling the deconvolution of cell fate and position identity. We demonstrate that the embryonic limb undergoes a complex multi-scale re-organization upon perturbation of one of its spatial organizing centers, including the loss of specific cell populations, specific alterations in the molecular identities of other pre-existing cell states and changes in their relative spatial distribution. Altogether, our study shows how multi-dimensional single-cell and spatially resolved molecular atlases could reveal the interconnected genetic networks that regulate the intricacies of organogenesis and its reorganization upon genetic alterations.

systems biology↗

bioRxiv2021

Effect of using a physical assistance device for movements involving trunk bending

Exoskeletons are a solution to physically relieve workers while allowing them to control the execution of their tasks and assist them (Baltrusch et al.2018). The study investigated in the search for elements able to quantify the action of a physical assistance device (PAD) on the human body for movements responsible for pathologies recognized as occupational diseases. The evaluation of a PAD allows to determine in which framework the exoskeleton can be useful for the realization of the movement. It is specified that a relevant way to insert exoskeletons in a company by always implementing a study or analysis beforehand to ensure its good integration. The objective of the study is to perform several tasks with and without the Posture Harness (HAPO) in order to analyze the kinematics of the movements and the electrical activity of erector muscles of the spine involved in carrying a load at work to understand its effects on the human body.

physiology↗

bioRxiv2020

Dissection of the Fgf8 regulatory landscape by in vivo CRISPR-editing reveals extensive inter- and intra-enhancer redundancy

Developmental genes are often regulated by multiple elements with overlapping activity. Yet, in most cases, the relative function of those elements and their contribution to endogenous gene expression remain uncharacterized. Illustrating this situation, distinct sets of enhancers have been proposed to direct Fgf8 in the limb apical ectodermal ridge (AER) and the midbrain-hindbrain boundary (MHB). Using in vivo CRISPR/Cas9 genome engineering, we functionally dissect this complex regulatory ensemble and demonstrate two distinct regulatory logics. In the AER, the control of Fgf8 expression appears extremely distributed between different enhancers. In contrast, in the MHB, one of the three active enhancers is essential while the other two are dispensable. Further dissection of the essential MHB enhancer revealed another layer of redundancy and identified two sub-parts required independently for Fgf8 expression and formation of midbrain and cerebellar structures. Interestingly, cross-species transgenic analysis of this enhancer suggests changes of the organisation of this essential regulatory node in the vertebrate lineage.

developmental biology↗

bioRxiv2017

Cell-nonautonomous local and systemic responses to cell arrest enable long-bone catch-up growth

Catch-up growth after insults to growing organs is paramount to achieving robust body proportions. In fly larvae, local injury is followed by local and systemic compensatory mechanisms that allow damaged tissues to regain proportions with other tissues. In vertebrates, local catch-up growth has been described after transient reduction of bone growth, but the underlying cellular responses are controversial. We developed an approach to study catch-up growth in foetal mice by inducing mosaic expression of the cell cycle suppressor p21 in the cartilage cells (chondrocytes) that drive long bone elongation. By specifically targeting the left hindlimb, the right limb served as an internal control. Strikingly, left-right limb symmetry was not altered, revealing deployment of compensatory mechanisms. Above a certain threshold of insult, an orchestrated response was triggered involving local enhancement of bone growth and systemic growth reduction that ensured body proportions were maintained. The local response entailed hyper-proliferation of spared left-limb chondrocytes that was associated with reduced chondrocyte density. The systemic effect involved impaired placental IGF signalling and function, revealing bone-placenta communication. Thus, vertebrates, much like invertebrates, can mount coordinated local and systemic responses to developmental insults to ensure normal body proportions are maintained.

developmental biology↗