Biology subjects

Truffault, V.

Publications and source records attributed to Truffault, V..

3 recordsLinked to original sources

bioRxiv2023

Photosynthesis is led by stomatal circadian rhythm and not by starch depletion after a long period of darkness

The circadian rhythm is an endogenous rhythm, defined by repeated metabolic oscillations every 24 hours under constant parameters. In plants, the circadian rhythm regulates the growth through photosynthesis and the management of carbohydrates. In indoor farming, the photoperiod is independent from the sunlight and is of interest to increase energy savings. In this work, we studied the effects of modifications of photoperiods on indoor-grown lettuces (L. sativa), which were then not tuned with the circadian rhythm. The pattern of photoperiods applied was: 16/12-16/8-16/8. A mutant-free study was carried out to avoid genes shutdown unintended side effects and to evaluate the impact of the circadian rhythm under marketable production conditions. We observed that the circadian regulation of the stomatal conductance was the main limiting factor of net photosynthesis when the photoperiod is exceptionally not tuned with the circadian rhythm. In our experiment, the disruption of the circadian rhythm decreased the photosynthetic activity by 6.2% throughout the light period, with no alteration of the yield, morphology or light and water use efficiencies. Furthermore, starch depletion induced by the changes in the photoperiod could not explain variations of the net photosynthetic activity during the following light period. Interestingly, disrupting the circadian rhythm saved 5% of lighting time compared to the control, which can be converted into energy savings. Consequently, the circadian rhythm can be defined as a limiting factor for reducing energy consumption in indoor farming. Further characterization of the links between the photosynthesis-carbohydrates-growth continuum and the circadian rhythm is thus required.

plant biology↗

bioRxiv2019

The human α-defensin-derived peptide HD5(1-9) inhibits cellular attachment and entry of human cytomegalovirus.

Human cytomegalovirus (HCMV) infection causes severe illness in newborns and immunocompromised patients. Since treatment options are limited there is an unmet need for new therapeutic approaches. Defensins are cationic peptides, produced by various human tissues, which serve as antimicrobial effectors of the immune system. Furthermore, some defensins are proteolytically cleaved, resulting in the generation of smaller fragments with increased activity. Together, this led us to hypothesize that defensin-derived peptides are natural human inhibitors of virus infection with low toxicity. We screened several human defensin HNP4- and HD5-derived peptides and found HD5(1-9) to be antiviral without toxicity at high concentrations. HD5(1-9) inhibited HCMV cellular attachment and thereby entry and was active against primary as well as a multiresistant HCMV isolate. Moreover, cysteine and arginine residues were identified to mediate the antiviral activity of HD5(1-9). Altogether, defensin-derived peptides, in particular HD5(1-9), qualify as promising candidates for further development as a novel class of HCMV entry inhibitors.\n\nAUTHOR SUMMARYDefensins are peptides produced by various human organs which take part in the natural defense against pathogens. Recently, it has been shown that defensins are further cleaved to smaller peptides that have high intrinsic anti-microbial activity. We here challenged the hypothesis that these peptides might have antiviral activity, and due to their presumably natural occurrence, low toxicity. Indeed, we found one peptide fragment that turned out to block the attachment of the human cytomegalovirus (HCMV) to cells. Furthermore, this peptide did not show toxicity in various cellular assays or impede the embryonic development of zebrafish at the concentrations used to block HCMV. This is important, since HCMV is one of the most important viral congenital infections. Altogether, our results hold promise for the development of a new class of antivirals against HCMV.

microbiology↗

bioRxiv2018

NMR Protein Structure Determination via Local Conformational Mapping

The ability of proteins to adopt multiple conformational states is essential to their function and elucidating the details of such diversity under physiological conditions has been a major challenge. Here we present a generalized method for mapping protein population landscapes by NMR spectroscopy. Experimental NOESY spectra are directly compared to a set of expectation spectra back-calculated across an arbitrary conformational space. Signal decomposition of the experimental spectrum then directly yields the relative populations of local conformational microstates. In this way, averaged descriptions of conformation can be eliminated. As the method quantitatively compares experimental and expectation spectra, it inherently delivers an R-factor expressing how well structural models explain the input data. We demonstrate that our method extracts sufficient information from a single 3D NOESY experiment to perform initial model building, refinement and validation, thus offering a complete de novo structure determination protocol.

biophysics↗