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Genome rearrangements induced by the stimulation of end-joining of DNA double strand breaks through multiple phosphorylation of MRE11 by the kinase PKB/AKT1.
No full textInternational audienceAbstract Genetic instability is a major hazard threatening the fate of cells and ultimately of organisms. DNA double-strand break (DSB) is a highly toxic lesion, jeopardizing genome stability. Using cytogenetic and differential exome sequencing, we show here that upregulation of the kinase PKB/AKT1 leads to genomic rearrangements and chromosome fusions. By combining various approaches, at the genome scale and at precise loci, we show that PKB/AKT1 stimulates DSB end-joining, leading to inter- and intrachromosomal genomic rearrangements. The MRE11–RAD50–NBS1 (MRN) complex plays an essential role in the early steps of DSB signaling/repair. We show here that PKB/AKT1 favors the assembly of MRN, leading to the stimulation of DSB signaling via the MRE11/ATM axis. We identify MRE11 as a phosphorylation effector of PKB/AKT1 and reveal several sites whose phosphorylation is required for PKB-mediated stimulation of DSB end-joining and chromosome fusions. These data reveal that PKB/AKT1 actively promotes genetic instability by increasing the efficiency of DSB end-joining through MRE11 phosphorylation on these sites. These results highlight that not only a defect of DSB signaling/repair but also its stimulation, can lead to genome rearrangements and underline the importance of a precise regulation of the DNA damage response to maintain genome stability
Impacts of Agricultural Intensification on Weed Floral and Competitive Traits: A Spatiotemporal Study in French Vineyards and Annual Crops
No full textWeeds play a dual role in agroecosystems, offering both ecosystem services and disservices. Agricultural intensification, particularly herbicide use, has reshaped weed communities, with distinct effects in annual and perennial systems. However, how intensification influences weed multifunctionality—especially in terms of competition and pollination—remains limited.This study explores how weed communities respond to agricultural intensification along spatial and temporal gradients, focusing on traits related to competition and pollination. We examine (1) variation in floral and competitive traits across cropping systems, (2) their responses to management practices, especially herbicides, using national weed surveys from annual crops and vineyards, and (3) long-term changes in floral functional diversity, using two diachronic weed survey datasets.Our results show that vineyards support weed communities more favourable to pollinators than annual crops. While herbicides reduce floral resources in annual systems, practices such as tillage and mowing in vineyards can help maintain floral diversity. In contrast, competitive traits showed no consistent response to herbicide use, highlighting context-dependent effects.Over time, we observed diverging trends in weed floral diversity: a decline in annual crops from the 1970s to 2020s, and an improvement in vineyards from the 1980s onward. These results underscore the importance of considering both functional roles of weeds and their management context. To fully grasp the contribution of weeds to agroecosystem multifunctionality, long-term monitoring of weed–pollinator interactions and farming practices is essential
The Impact of Virtual Object Interaction on Episodic Memory: The Role of Bodily-Self Consciousness and Presence
No full textInternational audienceEpisodic memory, key to reliving specific events [1], is often measured through standardized tests that do not always capture its nuances. Virtual reality (VR), with its immersive environment, offers a new approach to exploring this memory. This study examines the impact of interaction with virtual objects, Bodily-Self Consciousness (BSC), and the sense of presence on episodic memory in VR. Thirty-two participants were immersed in a virtual environment where they could manipulate certain objects. After the experience, they completed questionnaires about their BSC and sense of presence. Twenty-four hours later, a free recall task was used to assess their episodic memory, focusing on the objects, their details, and their location. Participants also rated their confidence in their memories. The results show that interaction with virtual objects improves memory for the objects and their details, highlighting the importance of motor interaction. However, this interaction did not influence participants' confidence in the location of the objects, suggesting that different types of information should be distinguished when evaluating memory. Although the effects of BSC and the sense of presence on memory were not observed, a link between BSC and presence was identified, showing that bodily awareness enhances the perception of presence in VR. These results suggest the need for further investigation into these relationships and the development of more precise assessment tools to better understand episodic memory in VR.</div
ACTES DU 14ème COLLOQUE DE GEOPHYSIQUE DES SOLS ET DES FORMATIONS SUPERFICIELLES (GEOFCAN 2025)
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Morphometric study of the bony labyrinth of the inner ear in the European moles <i>Talpa europaea</i>, <i>Talpa occidentalis</i>, and <i>Talpa aquitania</i>
No full textInternational audienceThe inner ear, particularly the semicircular canals system, plays a crucial role in balance and spatial navigation. It has previously been investigated to understand if its shape is related to the ecology: it is indeed known to be a good predictor for the extreme ecological niche of burrowing or arboreal organisms, although being strongly driven by the phylogeny. Recent phylogenetic studies of European moles have revealed the paraphyletic status of the species Talpa europaea and the description of new parapatric species in south-western Europe. Following the description of the new mole species Talpa aquitania, its forelimb morphology has been compared to those of its two sister species, Talpa europaea and Talpa occidentalis, revealing inter- and intra-specific morphological discrimination. The present study aims to compare the morphologies of the semicircular canal system in these three sister species of moles. Geometric morphometrics was used on 58 specimens representing the three species to analyze shape-related information and quantify the variability. The results demonstrate interspecific variability in the shape of the semicircular canals within the three species and intraspecific variability across sampling sites. Furthermore, no sexual dimorphism was observed for the bony labyrinth. The observed variability is likely influenced by the distinct ecological characteristics of the habitats housing the three Talpa species and their populations or by genetic differences resulting from their evolutionary history
The Accidental Capture of a Newborn Shortfin Mako Shark Isurus oxyrinchus (Rafinesque, 1810) in the Northwestern Mediterranean Sea off the Coast of Marseille, France
No full textInternational audienceA small-sized shark was accidentally caught in the coastal waters of southeastern France and abandoned in the port of L’Estaque (Marseille) in May 2024. An autopsy revealed that it was a young female shortfin mako, Isurus oxyrinchus (Rafinesque, 1810). Numerous superficial wounds on the head, back, and flanks, in the form of parallel striations resulting from heavy friction, indicate meshing in a gillnet that provoked the animal’s death by asphyxiation. Its very small size (64.77 cm TL) suggests that this is a newborn individual, leading to the hypothesis that the waters off Marseille could be a nursery area for this species. This observation alone is not enough to prove this point, but it does suggest the need for closer monitoring to validate it. Should the area be proven to play this key role for this critically endangered species, measures to limit fishing pressure would be essential, particularly during the parturition period between February and May
Pigment‐Macromolecule Complexes Isolation from Sea Urchin Biomineral Waste for Coloring Materials
No full textInternational audienceThe production and widespread use of synthetic pigments and dyes have significant environmental and health impacts. Despite this, synthetic colorants remain dominant due to their wide color range, high stability, strong tinting power, and lower cost compared to natural alternatives. Therefore, to offer sustainable and competitive substitutes, eco‐friendly methods for producing bio‐based pigments with similar performance are essential. Herein, a methodology has been developed to extract the entire colored organic fraction occluded within seashell biomineral waste, which comprises pigments and pigment‐macromolecule complexes. This process involves an optimized cleaning procedure of the biomineral soft tissues, a tailored biochemical extraction, and detailed characterization of the extracted fraction. Applied to sea urchin skeletons, this method successfully isolates polyhydroxylated naphthoquinone (PHNQ)‐macromolecule complexes. These complexes show superior pH stability in purple hues compared to free PHNQ, which shifts from red to purple in basic conditions. Notably, the approach enhances colorant yield by up to five times. These results, together with mineral pigment synthesis and fabric dyeing assays performed with the extracted colored organic fraction, contribute to a better understanding of the origin of color in biominerals and reveal the versatility of these natural pigments for environmentally friendly coloring of both organic and inorganic materials
