Biology subjects

Baduel, L.

Publications and source records attributed to Baduel, L..

5 recordsLinked to original sources

bioRxiv2025

Regeneration of distinct complex structures in the annelid Platynereis is partially based on common morphological, cellular, and molecular events

Many metazoan species harbor fascinating regenerative capabilities, but the underlying mechanisms remain poorly understood. Whether the capacity to regenerate complex structures successfully relies on common or divergent features is still an open question. To identify the key molecular and cellular elements necessary for successful regeneration, we investigated the efficient regeneration of two distinct complex structures in the annelid worm Platynereis dumerilli. By combining classical morphological and developmental approaches, with state-of-the-art single-cell RNA sequencing and analysis, we conducted a comprehensive comparison of locomotory appendage and posterior part regeneration. We uncovered the rich cell type diversity of this Platynereis appendage, over a third of which are nerve-related populations, highlighting the importance of its sensory function. We also described its regenerative process at the morphological and cellular levels, defining stages that include the formation of a proliferative blastema. We then compared posterior part and appendage blastemas, specifically assessing their cell diversity and cell differentiation trajectories. We found transcriptionally similar epithelial and mesodermal progenitors at play during posterior and appendage regeneration, although their specific trajectories differed to some extent. Our work, revealing partial morphological, molecular and cellular parallels between these two efficient regenerations within a single species, sets the foundation for addressing the fundamental question of regeneration success in animals.

developmental biology↗

bioRxiv2025

Multifaceted conserved functions of Notch during post-embryonic neurogenesis in the annelid Platynereis

Notch signaling is an evolutionarily conserved pathway known to orchestrate neurogenesis by regulating the transition of progenitor cells to differentiated neurons and glia, as well as by directing neurite outgrowth and axon guidance in many species. Although extensively studied in vertebrates and ecdysozoans, the role of Notch in spiralians (including mollusks, annelids or flatworms) remains largely unexplored, limiting our understanding of its conserved functions across bilaterians. In this study, we focus on the segmented annelid Platynereis dumerilii, a model organism in neurobiology and regeneration, to investigate Notch signaling functions during post-embryonic developmental processes. We show that Notch pathway components are expressed in neurogenic territories during both posterior elongation and regeneration, two processes requiring sustained neurogenesis. Through chemical inhibitions of the pathway and RNA-seq profiling, we demonstrate that Notch signaling regulates neural progenitor specification, differentiation, and overall neurogenic balance in the regenerating and elongating posterior part. Moreover, disruption of Notch activity leads to severe defects in pygidial and central nervous system organization, including abnormal axon guidance and impaired neurite outgrowth. Altogether, our results support the hypothesis that Notch has multifaceted conserved functions in neurogenesis across bilaterians, shedding light on the ancestral functions of this critical pathway.

developmental biology↗

bioRxiv2024

The rich evolutionary history of the ROS metabolic arsenal shapes its mechanistic plasticity at the onset of metazoan regeneration

Regeneration, the ability to restore body parts after injury, is widespread in metazoans; however, the underlying molecular and cellular mechanisms involved in this process remain largely unknown, and its evolutionary history is consequently unresolved. In the last decade, ROS have emerged as shared actors that trigger apoptosis and cell proliferation to drive regenerative success in a few metazoan models. However, it is not known whether the contribution of ROS to regeneration relies on conserved mechanisms in animals. Here we performed a comparative genomic analysis of ROS metabolism actors across metazoans, and carried out a comparative study for the deployment and roles of ROS during regeneration in two different research models: the annelid Platynereis dumerilii and the cnidarian Nematostella vectensis. We established that the vast majority of metazoans possess a core redox kit allowing for the production and detoxification of ROS, and overall regulation of ROS levels. However, the precise composition of the redox arsenal can vary drastically from species to species, suggesting that evolutionary constraints apply to ROS metabolism functions rather than precise actors. We found that ROS are produced during and are necessary for regeneration in both Platynereis and Nematostella. However, we also uncovered different enzymatic activities underlying ROS dynamics, as well as distinct effects of ROS signalling on injury-induced apoptosis and cell proliferation in the two species. We conclude that, while ROS are a robust feature of metazoan regeneration, their production and contribution to this phenomenon may depend on plastic molecular mechanisms.

developmental biology↗

bioRxiv2023

Antero-posterior gradients of cell plasticity and proliferation modulate posterior regeneration in the annelid Platynereis

Regenerative abilities are extremely variable among animals and may be substantial in some phyla, such as the annelids. So far, the cellular mechanisms underlying regeneration in annelids remain elusive. To precisely determine the origin(s), plasticity and fate of the cells participating in the blastema formation during posterior regeneration in the annelid Platynereis dumerilii, we developed specific tools to track proliferative cells as well as gut epithelial cells. We showed that two populations of progenitors are at play during regeneration and that, among them, gut progenitors from differentiated tissues are lineage-restricted. Strikingly, gut progenitors from less differentiated and more proliferative tissues are much more plastic and can produce ectodermal and mesodermal derivatives, in addition to gut cells. However, their plasticity is de facto limited as exemplified by their inability to regenerate populations of stem cells responsible for the constant growth of the worms. We evidenced that those stem cells are from local origin (i.e. from the segment abutting the amputation plan) as most of the blastema cells. Our results are in favour of a hybrid and flexible cellular model for posterior regeneration in Platynereis relying on a gradient of cell plasticity along the antero-posterior axis of the animal.

developmental biology↗

bioRxiv2023

Transcriptomic landscape of posterior regeneration in the annelid Platynereis dumerilii

Background: Restorative regeneration, the capacity to reform a lost body part following amputation or injury, is an important and still poorly understood process in animals. Annelids, or segmented worms, show amazing regenerative capabilities, and as such are a crucial group to investigate. Elucidating the molecular mechanisms that underpin regeneration in this major group remains a key goal. Among annelids, the nereididae Platynereis dumerilii (re)emerged recently as a front-line regeneration model. Following amputation of its posterior part, Platynereis worms can regenerate both differentiated tissues of their terminal part as well as a growth zone that contains putative stem cells. While this regeneration process follows specific and reproducible stages that have been well characterized, the transcriptomic landscape of these stages remains to be uncovered. Results: We generated a high quality de novo Reference transcriptome for the annelid Platynereis dumerilii. To do so, we produced and analyzed three RNA-sequencing datasets, encompassing five stages of posterior regeneration, along with blastema stages and non-amputated tissues as controls. We included these regeneration RNA-seq datasets, as well as embryonic and tissue-specific datasets from the literature to produce a Reference transcriptome. We used this Reference transcriptome to perform in depth analyzes of RNA-seq data during the course of regeneration to reveal the important dynamics of the gene expression, process with thousands of genes differentially expressed between stages, as well as unique and specific genes expression at each regeneration stage. The study of these genes highlighted the importance of the nervous system at both early and late stages of regeneration, as well as the enrichment of RNA-binding proteins (RBPs) during almost the entire regeneration process. Conclusions: In this study, we provided a high-quality de novo Reference transcriptome for the annelid Platynereis that is useful for investigating various developmental processes, including regeneration. Our extensive stage-specific transcriptional analysis during the course of posterior regeneration shed light upon major molecular mechanisms and pathways, and will foster many specific studies in the future.

genomics↗