Impact of chlororespiration on non-photochemical quenching of chlorophyll fluorescence and on the regulation of the diadinoxanthin cycle in the diatom Thalassiosira pseudonana

In diatoms, metabolic activity during long dark periods leads to a chlororespiratory electron flow, which is accompanied by the build-up of a proton gradient strong enough to activate the diadinoxanthin (Ddx) de-epoxidation reaction of the Ddx cycle. In the present study, the impact of chlororespiration on non-photochemical quenching (NPQ) of chlorophyll fluorescence and the regulation of the Ddx cycle in the diatom Thalassiosira pseudonana was investigated by manipulation of the redox state of the photosynthetic electron transport chain during darkness. The response of a transfer of T. pseudonana cells from growth light conditions to 60 min darkness was found to depend on oxygen: in its presence there was no significant reduction of the PQ pool and no de-epoxidation of Ddx to diatoxanthin (Dtx). Under anaerobic conditions a high reduction state of the electron transport chain and a slow but steady de-epoxidation of Ddx was observed, which resulted in a significant accumulation of Dtx after 60 min of anaerobiosis. Unexpectedly, this high concentration of Dtx did not induce a correspondingly high NPQ as it would have been observed with Dtx formed under high light conditions. However, the sensitivity of NPQ to Dtx in cells kept under dark anaerobic conditions increased during reoxygenation and far-red (FR) light illumination. The results are discussed with respect to the activation of the de-epoxidation reaction and the formation of NPQ and their dependence on the extent of the proton gradient across the thylakoid membrane

Coordinations between gene modules control the operation of plant amino acid metabolic networks

<p>Abstract</p> <p>Background</p> <p>Being sessile organisms, plants should adjust their metabolism to dynamic changes in their environment. Such adjustments need particular coordination in branched metabolic networks in which a given metabolite can be converted into multiple other metabolites via different enzymatic chains. In the present report, we developed a novel "Gene Coordination" bioinformatics approach and use it to elucidate adjustable transcriptional interactions of two branched amino acid metabolic networks in plants in response to environmental stresses, using publicly available microarray results.</p> <p>Results</p> <p>Using our "Gene Coordination" approach, we have identified in Arabidopsis plants two oppositely regulated groups of "highly coordinated" genes within the branched Asp-family network of Arabidopsis plants, which metabolizes the amino acids Lys, Met, Thr, Ile and Gly, as well as a single group of "highly coordinated" genes within the branched aromatic amino acid metabolic network, which metabolizes the amino acids Trp, Phe and Tyr. These genes possess highly coordinated adjustable negative and positive expression responses to various stress cues, which apparently regulate adjustable metabolic shifts between competing branches of these networks. We also provide evidence implying that these highly coordinated genes are central to impose intra- and inter-network interactions between the Asp-family and aromatic amino acid metabolic networks as well as differential system interactions with other growth promoting and stress-associated genome-wide genes.</p> <p>Conclusion</p> <p>Our novel Gene Coordination elucidates that branched amino acid metabolic networks in plants are regulated by specific groups of highly coordinated genes that possess adjustable intra-network, inter-network and genome-wide transcriptional interactions. We also hypothesize that such transcriptional interactions enable regulatory metabolic adjustments needed for adaptation to the stresses.</p

Étude LyTONEPAL : cohorte nationale de nouveau-nés à terme ou proche du terme présentant une encéphalopathie anoxo-ischémique : évaluation de la prévalence et description de la population d’étude

The objective of this study was to present the first results of the French national cohort of late preterm and term newborns with Hypoxic Ischemic Encephalopathy (HIE) called LyTONEPAL - Long Term Outcome of Neonatal EncePhALopathy : prevalence of the disease and description of the study population. Data were collected through the database of the cohort. Maternals characteristics were compared to the data of 2016 French National Perinatal Survey. Neonatal characteristics were compared to 3 international cohorts of newborns with HIE. To assess the exhaustive recording of all HIE cases, LyTONEPAL database and a French medico-administrative database were linked. The total number of identified HIE was related to the number of live births in France during the same period. 1 039 586 children were born in France from September 2015 to March 2017. 791 children were included in LyTONEPAL. 20.6% died. Multiparious women and late preterm infants were more represented. The 5 minutes median Apgar score was of 4. The mean pH in umbilical cord blood was of 6.95. 59.1% presented moderate HIE and 30.1% severe HIE. 85% were treated with whole-body hypothermia. 582 children will be followed-up until the age of 3 years. The completeness check of the database is still in progress, therefore the prevalence cannot yet be calculated. The first results of LyTONEPAL find a gravity distribution comparable to that of the literature. The 3-year follow-up of these 582 children will make possible to estimate the frequency of neurological disability and its risk factors.L’objectif de l’étude était de présenter les premiers résultats de la cohorte nationale prospective LyTONEPAL - Long Term Outcome of Neonatal EncePhALopathy - d’enfants à terme ou proche du terme atteints d’encéphalopathie anoxo-ischémique (EAI) : prévalence de la maladie et description de la population d’étude. Les données étaient issues de la base de données LyTONEPAL. Les caractéristiques maternelles ont été comparées aux données de l’Enquête Nationale Périnatale de 2016 et les caractéristiques néonatales à 3 cohortes étrangères évaluant les EAI. Pour évaluer l’exhaustivité de la cohorte LyTONEPAL, la base de données a été appariée à la base de données nationale PMSI. Le nombre total d’EAI identifiées a été rapporté au nombre de naissances vivantes en France durant la même période. Entre septembre 2015 et mars 2017, 1 039 586 enfants sont nés en France. 791 enfants ont été inclus dans LyTONEPAL. 20.6 % sont décédés. Les mères étaient plus âgées et accouchaient plus par césarienne. De manière originale, il y avait plus de simples prématurés et les mères étaient plus multipares. Le score d’Apgar médian à 5 minutes était de 4. Le pH au cordon moyen de 6.95. 59.1 % présentaient une EAI modérée et 30.1% une EAI sévère. 85% ont bénéficié d’une hypothermie thérapeutique. 582 des enfants seront suivis jusqu’à l’âge de 3 ans. Le contrôle d’exhaustivité de la base de données étant en cours, la prévalence ne peut pas encore être calculée. Les premiers résultats de LyTONEPAL retrouvent une population de gravité comparable à celle de la littérature. Le suivi à 3 ans de 582 enfants permettra d’estimer la fréquence de l’invalidité neurologique et ses facteurs de risque

Lipids in Plants and Algae: From Fundamental Science to Industrial Applications Preface

International audienc

Lipids in Plants and Algae: From Fundamental Science to Industrial Applications Preface

International audienc