Biology subjects

Morell, C.

Publications and source records attributed to Morell, C..

4 recordsLinked to original sources

bioRxiv2025

Ecology of the exotic macroalga Batophora occidentalis in Posidonia oceanica meadows and other native benthic habitats

Marine invasive macroalgae can be particularly detrimental to native ecosystems. The exotic green macroalga B. occidentalis was first reported in 2020 in Estany des Peix lagoon in Formentera (Spain). In 2023 and 2024, our surveys revealed that B. occidentalis had spread to 100% of the surveyed locations within the lagoon. In 2024, B. occidentalis reached an average cover of 30% in Cymodocea nodosa meadows and 26% in Caulerpa prolifera meadows, with respective biomasses of 52 g m-1 and 44 g m-1, making it the most abundant macrophyte in these two native benthic habitats. We also found exotic B. occidentalis growing epiphytically on the leaves and rhizomes of Posidonia oceanica within the lagoon, with an average cover of 12% in 2023 and 16% in 2024, and a biomass of 3 g m-1 in 2024. Notably, it covered nearly 25% of the P. oceanica leaf surface and reached up to five times the weight of individual leaves. Alarmingly, we report the presence of a B. occidentalis specimen on a P. oceanica shoot in a nearby meadow outside the lagoon, signaling a potential spread beyond its current range. Additionally, B. occidentalis colonized various natural and hard substrates--including boat hulls, as it was found growing on 17 % of boats anchored in the only marina in the lagoon. With this study, we aim to encourage prompt action from local and regional governments. We may be witnessing the early stages of a broader B. occidentalis expansion, highlighting a critical moment for implementing early management measures such as monitoring, and, if possible, containment within the lagoon.

ecology↗

bioRxiv2022

Single-cell atlas of human liver development reveals pathways directing hepatic cell fates

The liver has been studied extensively due to the broad number of diseases affecting its vital functions. However, therapeutic advances, especially in regenerative medicine, are currently hampered by the lack of knowledge concerning human hepatic cell development. Here, we addressed this limitation by describing the developmental trajectories of different cell types comprising the human fetal liver at single-cell resolution. These transcriptomic analyses revealed that sequential cell-to-cell interactions direct functional maturation of hepatocytes, with non-parenchymal cells playing critical, supportive roles during organogenesis. We utilised this information to derive bipotential hepatoblast organoids and then exploited this novel model system to validate the importance of key signalling pathways and developmental cues. Furthermore, these insights into hepatic maturation enabled the identification of stage-specific transcription factors to improve the functionality of hepatocyte-like cells generated from human pluripotent stem cells. Thus, our study establishes a new platform to investigate the basic mechanisms of human liver development and to produce cell types for clinical applications.

developmental biology↗

bioRxiv2021

A dynamic view of histone tails interaction with clustered abasic sites in a nucleosome core particle

Apurinic/apyrimidinic sites are the most common DNA damage under physiological conditions. Yet, their structural and dynamical behavior within nucleosome core particles has just begun to be investigated, and show dramatic differences with the one of abasic sites in B-DNA. Clusters of two or more abasic sites are repaired even less efficiently and hence constitute hotspots of high mutagenicity notably due to enhanced double-strand breaks formation. Based on a X-ray structure of a 146-bp DNA wrapped onto a histone core, we investigate the structural behavior of two bistranded abasic sites positioned at mutational hotspots along microsecond-range molecular dynamics simulations. Our simulations allow us to probe histone tails interactions at clustered abasic sites locations, with a definitive assignment of the key residues in-volved in the NCP-catalyzed formation of DNA-protein cross-linking in line with recent experimental findings, and pave the way towards a systematic assessment of histone tails response to DNA lesions.

biochemistry↗

bioRxiv2020

Nucleosomal embedding reshapes the dynamics of abasic sites

Apurinic/apyrimidinic (AP) sites are the most common DNA lesions, which benefit from a most efficient repair by the base excision pathway. The impact of losing a nucleobase on the conformation and dynamics of B-DNA is well characterized. Yet AP sites seem to present an entirely different chemistry in nucleosomal DNA, with lifetimes reduced up to 100-fold, and the much increased formation of covalent DNA-protein cross-links, refractory to repair. We report microsecond range, all-atom molecular dynamics simulations that capture the conformational dynamics of AP sites and their tetrahydrofuran analogs at two symmetrical positions within a nucleosome core particle, starting from a recent crystal structure. Different behaviours between the deoxyribo-based and tetrahydrofuran-type abasic sites are evidenced. The two solvent-exposed lesion sites present contrasted extrahelicities, revealing the crucial role of the position of a defect around the histone core. Our all-atom simulations also identify and quantify the occurrence of several spontaneous, non-covalent interactions between AP and positively-charged residues from the histones H2A and H2B tails that prefigure DNA-protein cross-links. This study paves the way towards an in silico mapping of DNA-protein cross-links.

biochemistry↗