Modélisation des conditions d’environnement des bocaux de culture in vitro : bocaux avec agar et vitroplants

La présente étude traite de la modélisation des conditions des plantes en culture in vitro. Lorsque des vitroplants sont introduits dans les bocaux,l'humidité de l'air intérieur varie en fonction de leur stade de développementet ce en accord avec les courbes expérimentales. Les variations diurnes du déficit de pression de vapeur (DPV) présentent un maximum pendant laphotopériode et un minimum pendant la nyctipériode. Par ailleurs, grâce à la prise en compte des réservoirs de la plante, le modèle permet de décrire la déshydratation et la réhydratation des tissus, ce qui est potentiellement d'un intérêt pratique. Au cours du cycle diurne, la teneur en eau relative varie entre 75 et 90 %. Les flux d'eau dans la plante concordent bien avec les variations de la teneur en eau du réservoir plante et caractérisent bien les deux types de régimes de circulation de l'eau dans la plante : le régime de flux conservatif et le régime de flux non conservatif.Mots-clés : Modélisation, culture in vitro, humidité de l'air intérieur, réservoir-plante, déshydratation, réhydratatio

Enhanced prefrontal serotonin 5-HT1A currents in a mouse model of Williams-Beuren syndrome with low innate anxiety

Williams-Beuren syndrome (WBS) is a neurodevelopmental disorder caused by the hemizygous deletion of 28 genes on chromosome 7, including the general transcription factor GTF2IRD1. Mice either hemizygously (Gtf2ird1+/−) or homozygously (Gtf2ird1−/−) deleted for this transcription factor exhibit low innate anxiety, low aggression and increased social interaction, a phenotype that shares similarities to the high sociability and disinhibition seen in individuals with WBS. Here, we investigated the inhibitory effects of serotonin (5-HT) on the major output neurons of the prefrontal cortex in Gtf2ird1−/− mice and their wildtype (WT) siblings. Prefrontal 5-HT receptors are known to modulate anxiety-like behaviors, and the Gtf2ird1−/− mice have altered 5-HT metabolism in prefrontal cortex. Using whole cell recording from layer V neurons in acute brain slices of prefrontal cortex, we found that 5-HT elicited significantly larger inhibitory, outward currents in Gtf2ird1−/− mice than in WT controls. In both genotypes, these currents were resistant to action potential blockade with TTX and were suppressed by the selective 5-HT1A receptor antagonist WAY-100635, suggesting that they are mediated directly by 5-HT1A receptors on the recorded neurons. Control experiments suggest a degree of layer and receptor specificity in this enhancement since 5-HT1A receptor-mediated responses in layer II/III pyramidal neurons were unchanged as were responses mediated by two other inhibitory receptors in layer V pyramidal neurons. Furthermore, we demonstrate GTF2IRD1 protein expression by neurons in layer V of the prefrontal cortex. Our finding that 5-HT1A-mediated responses are selectively enhanced in layer V pyramidal neurons of Gtf2ird1−/− mice gives insight into the cellular mechanisms that underlie reduced innate anxiety and increased sociability in these mice, and may be relevant to the low social anxiety and disinhibition in patients with WBS and their sensitivity to serotonergic medicines

Circuit-based interrogation of sleep control.

Sleep is a fundamental biological process observed widely in the animal kingdom, but the neural circuits generating sleep remain poorly understood. Understanding the brain mechanisms controlling sleep requires the identification of key neurons in the control circuits and mapping of their synaptic connections. Technical innovations over the past decade have greatly facilitated dissection of the sleep circuits. This has set the stage for understanding how a variety of environmental and physiological factors influence sleep. The ability to initiate and terminate sleep on command will also help us to elucidate its functions within and beyond the brain

Liens entre croissance et paramètres hydriques chez les nœuds axillaires d'Hevea brasiliensis en phase d'introduction in vitro

L'augmentation du poids de matière sèche des vitroplants d'Hevea brasiliensis présente 3 phases distinctes : une phase de latence du 1er au 16 e j de culture, pendant laquelle l'atmosphère au-dessus des plants est proche de la saturation; puis une phase de croissance rapide, du 16e au 30e j de culture et une phase de croissance lente du 30e au 80e j pendant lesquelles l'atmosphère est plus sèche. Le suivi de l'évolution de l'état hydrique des plants et du milieu gélosé permet d'émettre l'hypothèse suivante : du 1 er au 16e j de culture, les plants ne peuvent pas prélever de l'eau dans le milieu gélosé; lorsque l'atmosphère est plus sèche, le flux d'eau entre plant et atmosphère favorise l'entrée d'eau du milieu gélosé dans les plants jusqu'au 30e j de culture. Au-delà, l'évaporation à l'intérieur du bocal a asséché suffisamment le milieu gélosé pour que les plants présentent les symptômes de plants hydriquement stressés.Relations between growth and water parameters in axillary nodes of in vitro cultures of Hevea brasiliensis. The increase in weight of dry matter in in vitro Hevea brasiliensis is divided into 3 stages: a latency stage from the first to the 16th d of culture, during which the atmosphere inside the growth vessels is near saturation; then a fast growth stage from the 6th to the 30th d of culture, and an irregular growth from the 30th to the 80th day during which the atmosphere is drier (fig 1). The plant and medium water status variation (figs 2 and 3) led us to propose the following hypothesis: from the first to the 16th day, plants could not take up water from the medium; as the atmosphere became drier, the water flux between plant and atmosphere favoured water uptake in the plants until the 30th day. Afterwards, evaporation inside the vessel dried out the medium and plants presented symptoms of water stress

Inhibition of wound-induced ethylene does not prevent red discoloration in fresh-cut endive (Cichorium intybus L.)

Contains fulltext : 76056.pdf (publisher's version ) (Closed access)7 p