Biology subjects

Gascon, E.

Publications and source records attributed to Gascon, E..

4 recordsLinked to original sources

bioRxiv2025

Outer epidermal edges mediate cell-cell adhesion for tissue integrity in plants

Cell-cell adhesion in plants is generally thought to be primarily mediated by the middle lamella, a supposedly thin adhesive layer of the cell wall. Here, we challenge this view. Through computational simulation we found that outer edges of cellular interfaces of the epidermis are hotspot for cell separating tensile stress. Characterization of the ultrastructure of those edges in planta revealed that they are locally thickened regions that harbor cellulose lamellae and pectin-based structural continuity across adjacent cells. We confirmed their dominant role for adhesion by studying mutants where those edges are defective and through direct mechanical testing. This reveals the key role of outer epidermal cell edges, rather than the middle lamella, in mediating cell-cell adhesion for tissue integrity in plants.

plant biology↗

bioRxiv2023

Neurodevelopmental timing and socio-cognitive development in a prosocial cooperatively breeding primate (Callithrix jacchus)

Primate, and especially human, brain development is experience-dependent: it is shaped by the inputs received during critical periods. During early development, these inputs systematically differ between independently and cooperatively breeding species, because in cooperative breeders infants are interacting from birth with multiple caretakers and have to thrive in a richer and more challenging social environment. Here, we study the neurodevelopmental timing of the cooperatively breeding common marmoset and how it maps onto behavioral and developmental milestones. To obtain meaningful correlations of structure-function co-constructions, we combine behavioral, imaging (anatomical and functional) and neural tracing experiments. We focus on brain areas that are critically involved when observing conspecifics interacting with others and find that (i) these areas develop in clusters; (ii) these areas reach their maximum gray matter volume shortly after peak provisioning, when immatures are intensely provisioned by group members; (iii) the differentiation of these areas coincides with the period of intense negotiation between immatures and multiple adults over food, the birth of the next set of siblings, and the task of becoming a helper. Moreover, like in humans, differentiation is not fully completed at the age of first reproduction. In sum, we find that the developmental timing of social brain areas coincides with key social and developmental milestones in marmosets, and extends into early adulthood. This rich social input is likely critical for the emergence of the particularly strong prosociality and socio-cognitive skills of marmosets. Since humans are cooperative breeders too, these findings have strong implications for the evolution of human social cognition.

neuroscience↗

bioRxiv2022

The phosphoinositide signature guides the final step of plant cytokinesis

Plant cytokinesis, which fundamentally differs from that in animals, involves de novo assembly of a plasma membrane precursor named the cell plate. How the transition from the cell plate to a plasma membrane occurs at the end of the plant cytokinesis remains poorly understood. Here, we describe with unprecedented spatiotemporal precision, the acquisition of plasma membrane identity upon cytokinesis through the lateral patterning of phosphatidylinositol 4,5-bisphosphate PI(4,5)P2 at the newly formed cell plate membrane. We show that during late cytokinesis, opposing polarity domains are formed along the cell plate. Exclusion of PI(4,5)P2 from the leading edge of the cell plate is controlled by SAC9, a putative phosphoinositide phosphatase. SAC9 colocalizes with MAP65-3, a key regulator of the cytokinesis, at the cell plate leading zone and regulates its function. In the sac9-3 mutant, the polar distribution of PI(4,5)P2 at the cell plate is altered, leading to de-novo recruitment of the cytokinesis apparatus and to formation of an additional, ectopic cell plate insertion site. We proposed that PI(4,5)P2 acts as a polar cue to spatially separate the expansion and maturation domains of the forming cell plate during the final steps of cytokinesis. One Sentence SummaryThe phosphoinositide PI(4,5)P2 acts as an hallmark to guide the final step of plant cell division.

cell biology↗

bioRxiv2021

microRNA profiling uncovers region-specific molecular correlates of threat responses in a marmoset model of anxiety

Psychiatric diseases such as depression and anxiety are multifactorial conditions, highly prevalent in western societies. Human studies have identified a number of high-risk genetic variants for these diseases. Among them, polymorphisms in the promoter region of the serotonin transporter gene (SLC6A4) have attracted much attention. However, due to the paucity of experimental models, molecular alterations induced by these genetic variants and how they correlate to behavioral deficits have not been examined. Marmosets have emerged as a powerful model in translational neuroscience to investigate molecular underpinnings of complex behaviors. Here, we took advantage of naturally occurring genetic polymorphisms in marmoset SLC6A4 gene that have been linked to anxiety-like behaviors. Using FACS-sorted cells from different brain regions, we revealed that marmosets bearing different SLC6A4 variants exhibit distinct microRNAs signatures in a region of the prefrontal cortex whose activity has been consistently altered in patients with depression/anxiety. We also identified DCC, a gene previously linked to these diseases, as a downstream target of the dysregulated microRNAs. Significantly, we showed that levels of both microRNAs and DCC in this region were highly correlated to anxiety-like behaviors as well as to the response to citalopram, a selective serotonin re-uptake inhibitor and widely prescribed anti-depressant. Our findings establish links between genetic variants, molecular modifications in specific cortical regions and complex behavioral/pharmacological responses, providing new insights into gene-behavior relationships underlying human psychopathology.

neuroscience↗