Biology subjects

David, I.

Publications and source records attributed to David, I..

4 recordsLinked to original sources

bioRxiv2026

Dark-induced inactivation of the carbon assimilation process requires a water water cycle driven oxidative burst

Chloroplast metabolism is constantly fine-tuned by light availability through the perception and transmission of reductive and oxidative signals that activate or deactivate distinct metabolic enzymes. The reducing power originating from the photosynthetic electron transport chain has been shown to fuel the redox regulatory network, linking electron transport to the reductive activation of photosynthetic enzymes. However, the source of the oxidizing equivalents required to reverse photosynthetic enzyme activation and drive them toward an oxidized, inactive state has not yet been experimentally demonstrated. Here, we resolve redox dynamics associated with carbon assimilation inactivation by combining time-resolved redox imaging during the light-to-dark transition (LDT) with gas-exchange-based measurements. Dark-induced inactivation of carbon assimilation proved oxygen-dependent and coincided with an oxygen-dependent oxidative burst triggered during the LDT. This oxidative burst was suppressed under conditions that blocked electron transport to PSI or in plants in which PSI was photoinactivated. Notably, pgr5 and pgrl1ab mutants exhibited attenuated oxidative bursts and suppressed LDT-associated carbon assimilation inactivation, demonstrating that PGR5/PGRL1-dependent activity is required to generate the oxidative burst that drives CBC inactivation during LDT. These results establish a direct mechanistic link between oxygen- and PSI-dependent oxidative bursts and the inhibition of photosynthesis and mark the water-water cycle (WWC) as the primary source of the transient accumulation of oxidative equivalents that drive inactivation of Calvin-Benson cycle enzymes in darkness.

plant biology↗

bioRxiv2025

Transgenerational transmission of an environmental modification in quails: changes in phenotypic variance components across three generations

BackgroundWhile epigenetic variations can contribute to shaping phenotypic diversity, it can be challenging to isolate and quantify the portion of trait variability under non-genetic influence. In this study we compared the phenotypic responses for different traits of two epilines of Japanese quails (Coturnix japonica) across three generations, using a large sample size. These epilines were built in parallel following (epi +), or not (epi -), an initial genistein ingestion in the ancestors diet and were maintained to harbour a similar genetic structure. ResultsLinear models were fitted to extract the fraction of variance allocated to multiple factors such as family, sex and epiline. The latter was found to be significantly associated with body weight. The contribution of the epiline to phenotypic variability progressively increased from the first generation (G0) to the last (G2), leading - for example in body weight at slaughter - to an average difference for adult males and females in G2 of 9 grams and 14 grams respectively, between epi + offspring and controls (epi-). ConclusionsAlthough these findings suggest genetic drift, they could also reveal a possible transgenerational effect of the initial diet disruption. The analysis of other phenotypes displayed rare significant effects of the epiline. This innovative experimental design offered a unique opportunity to better understand the evolution of phenotypic variability and the parameters constituting it across three generations following or not an environmental change.

genetics↗

bioRxiv2022

Abscisic acid plays a key role in the regulation of date palm fruit ripening

The date palm (Phoenix dactylifera L.) fruit is of major importance for the nutrition of broad populations in the worlds desert strip; yet this crop is sorely understudied. Understanding the mechanisms regulating date fruit development and ripening is essential to customise this crop to the climatic change, which elaborates yield losses due to often too early occurring wet season. This study aimed to elucidate the mechanism regulating date fruit ripening. To that end, we followed the natural process of date fruit development and the effects of exogenous hormone application on fruit ripening in the elite cultivar Medjool. The results of the current study indicate that the onset of fruit ripening occurred once the seed had reached maximum dry weight. From this point until fruit harvest, the pulp endogenous abscisic acid (ABA) turned up and its levels consistently increased. The final stage in fruit ripening, the yellow-to-brown transition, was preceded by an arrest of xylem-mediated water transport into the fruit. Exogenous ABA application enhanced fruit ripening when applied just prior to the green-to-yellow fruit color transition. Repeated ABA applications hastened all fruit ripening processes, resulting in a significantly earlier harvest. The emerging pivotal role of ABA in the regulation of date fruit ripening is thoroughly discussed. HighlightsThe plant hormone abscisic acid (ABA) promotes date fruit ripening, as indicated by the enhanced change in fruit color, from green to yellow, and the enhanced rate of sugar accumulation.

plant biology↗

bioRxiv2021

Localizing Brain Function Based on Full Multivariate Activity Patterns: The Case of Visual Perception and Emotion Decoding

Multivariate statistics and machine learning methods have become a common tool to extract information represented in the brain. What is less recognized is that, in the process, it has become more difficult to perform data-driven discovery and functional localization. This is because multivariate pattern analysis (MVPA) studies tend to restrict themselves to a subset of the available data, or because sound inference to map model parameters back to brain anatomy is lacking. Here, we present a high-dimensional (including brain-wide) multivariate classification pipeline for the detection and localization of brain functions during tasks. In particular, we probe it at visual and socio-affective states in a task-oriented functional magnetic resonance imaging (fMRI) experiment. Classification models for a group of human participants and existing rigorous cluster inference methods are used to construct group anatomical-statistical parametric maps, which correspond to the most likely neural correlates of each psychological state. This led to the discovery of a multidimensional pattern of macroscale brain activity which reliably encodes for the perception of happiness in the visual cortex, lingual gyri and the posterior perivermian cerebellum. We failed to find similar evidence for sadness and anger. Anatomical consistency of discriminating features across subjects and contrasts despite the high number of dimensions suggests MVPA is a viable tool for a complete functional mapping pipeline, and not just the prediction of psychological states. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=134 SRC="FIGDIR/small/438425v3_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@1961forg.highwire.dtl.DTLVardef@26d25aorg.highwire.dtl.DTLVardef@bc4b35org.highwire.dtl.DTLVardef@1eda0a6_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗