Brainstem Respiratory Oscillators Develop Independently of Neuronal Migration Defects in the Wnt/PCP Mouse Mutant looptail

The proper development and maturation of neuronal circuits require precise migration of component neurons from their birthplace (germinal zone) to their final positions. Little is known about the effects of aberrant neuronal position on the functioning of organized neuronal groups, especially in mammals. Here, we investigated the formation and properties of brainstem respiratory neurons in looptail (Lp) mutant mice in which facial motor neurons closely apposed to some respiratory neurons fail to migrate due to loss of function of the Wnt/Planar Cell Polarity (PCP) protein Vangl2. Using calcium imaging and immunostaining on embryonic hindbrain preparations, we found that respiratory neurons constituting the embryonic parafacial oscillator (e-pF) settled at the ventral surface of the medulla in Vangl2Lp/+ and Vangl2Lp/Lp embryos despite the failure of tangential migration of its normally adjacent facial motor nucleus. Anatomically, the e-pF neurons were displaced medially in Lp/+ embryos and rostro-medially Lp/Lp embryos. Pharmacological treatments showed that the e-pF oscillator exhibited characteristic network properties in both Lp/+ and Lp/Lp embryos. Furthermore, using hindbrain slices, we found that the other respiratory oscillator, the preBötzinger complex, was also anatomically and functionally established in Lp mutants. Importantly, the displaced e-pF oscillator established functional connections with the preBötC oscillator in Lp/+ mutants. Our data highlight the robustness of the developmental processes that assemble the neuronal networks mediating an essential physiological function

Formation of steroids in human pregnancy.

In a first study, the rate of excretion of lbeta-hydroxyandrostenedione was investigated using two pools of human late pregnancy urine and was found to be 0.8 and 1.0 microgram per day. In the second part of the thesis the metabolism of 3H-dehydroisoandrosterone was investigated in human fetal adrenal maintained in monolayer culture and the factors regulating the growth of the cells and the formation of dehydroisoandrosterone sulfate were studied. Dehydroisoandrosterone was metabolized to androstenedione and androstenediol to a small extent in both primary and initial subcultures of human fetal adrenals. Dehydroisoandrosterone was extensively converted to its sulfate only in primary cell cultures but hot in initial subcultures. [...]Dans une première étape, nous avons mesuré à deux reprises chez la femme enceinte, au dernier trimestre de la grossesse, le taux d'excrétion urinaire de la l-hydroxyandrosteneioe et les résultats obtenus ont été: 0.8 et 1.0mcg par jour. Dans une deuxième phase, nous avons étudié d'une part, le métabolisme de la H3-déhydrodsoandrostérone par la surrénale de foetus humain maintenu en culture et d'autre part, les facteurs responsables de la croissance cellulaire et de la formation du sulfate de déhydroisoandrostérone. [...

Embryonic emergence of the respiratory rhythm generator.

International audienceBreathing is vital for life ex utero and therefore requires that the respiratory rhythm generator (RRG), the central neural network generating the continuous rhythmic motor command, be functional at birth. The RRG, located in the brainstem, appears to comprise two interacting respiratory oscillators: the parafacial respiratory group (pFRG), and the preBötzinger complex (preBötC). Data on the establishment of these respiratory oscillators during embryonic and foetal periods are beginning to be produced. The present paper provides a short review of the current knowledge regarding (i) the emergence of activity in the two respiratory oscillators and (ii) their functional coupling during prenatal development in rodents

Drought-adaptive mechanisms involved in the escape/tolerance strategies of Arabidopsis Landsberg erecta and Columbia ecotypes and their F1 reciprocal progeny

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Emergence of sigh rhythmogenesis in the embryonic mouse.

International audienceIn mammals, eupnoeic breathing is periodically interrupted by spontaneous augmented breaths (sighs) that include a larger-amplitude inspiratory effort, typically followed by a post-sigh apnoea. Previous in vitro studies in newborn rodents have demonstrated that the respiratory oscillator of the pre-Bötzinger complex (preBötC) can generate the distinct inspiratory motor patterns for both eupnoea- and sigh-related behaviour. During mouse embryonic development, the preBötC begins to generate eupnoeic rhythmicity at embryonic day (E) 15.5, but the network's ability to also generate sigh-like activity remains unexplored at prenatal stages. Using transverse brainstem slice preparations we monitored the neuronal population activity of the preBötC at different embryonic ages. Spontaneous sigh-like rhythmicity was found to emerge progressively, being expressed in 0/32 slices at E15.5, 7/30 at E16.5, 9/22 at E17.5 and 23/26 at E18.5. Calcium imaging showed that the preBötC cell population that participates in eupnoeic-like discharge was also active during fictive sighs. However, patch-clamp recordings revealed the existence of an additional small subset of neurons that fired exclusively during sigh activity. Changes in glycinergic inhibitory synaptic signalling, either by pharmacological blockade, functional perturbation or natural maturation of the chloride co-transporters KCC2 or NKCC1 selectively, and in an age-dependent manner, altered the bi-phasic nature of sigh bursts and their coordination with eupnoeic bursting, leading to the generation of an atypical monophasic sigh-related event. Together our results demonstrate that the developmental emergence of a sigh-generating capability occurs after the onset of eupnoeic rhythmogenesis and requires the proper maturation of chloride-mediated glycinergic synaptic transmission

Effect of Plant Species and Nutrient Loading Rates in Treatment Wetlands for Polluted River Water Under a Subtropical Climate

International audienceThe performance of 14 large pilot-scale horizontal flow wetlands (similar to 60 m(2)each) designed to treat polluted river water was tested in a 3-year study at the Chenshan Botanical Garden in Shanghai, China. Five local species,Arundo donax,Cyperus alternifolius,Phragmites australis,Thalia dealbataandTypha orientalis, were planted in monocultures and in a polyculture ofPhragmites,ThaliaandTypha.Total nitrogen (TN) removal was compared among species and to an unplanted bed.Each bed was replicated once, and the parallel setup received a TN inflow concentration of 16 mg L(-1)on average over each summer season, a level twice as high as for the beds receiving unspiked inflow. During the first 2 years of operation, the only significant differences in pollutant removal were between planted and unplanted systems. In the third year, significant differences appeared among planted beds in the high nutrient systems, withPhragmitesbeing the most efficient species in TN removal andArundothe least, suggesting that greater inflow and more maturity may be needed before differences can be detected. The polyculture was never significantly more efficient than the other planted systems. However, it ranked among the best systems in 2018. Yet, while a greater removal of the polyculture over the average TN removal of all monocultures taken together may develop over time, we found no evidence that the polyculture may get more efficient than the best monoculture. Observation over all phases of plant establishment made it possible to draw conclusions for future design and operation

Critères de dimensionnement pour des marais filtrants à flux horizontal sous-surfacique alimentés avec une eau faiblement chargée

International audience14 horizontal flow treatment wetlands for the removal of pollutants from stormwater in Shanghai Chenshan Botanical Garden in China were investigated in the second year of a long-term trial. One aimwas to compare the treatment efficiency of differently planted filter beds and unplanted ones. Despite the low nutrient concentrations, planted filters performed better than unplanted ones; e.g. for TN, the median removal efficiency for unplanted filters were 53% and 76% for planted filters. However, no correlations between dissolved oxygen and removal efficiency of oxygen depleting pollutants as well as between differently planted filters could be found. Regarding the targeted optimisation of the wetland design, for the investigated parameters COD, BOD5, NH3-N, TN and TP, the filter beds would perform almost as good if shortened by 1/3 of the length. However, it needs to be considered if further treatment goals such as reduction of pathogens should be achieved – here, the full filter passage might be necessary to achieve sufficient results. This should be subject to further research.Au Jardin botanique de Chenshan (Shanghai), une station expérimentale composée de 14 marais filtrants à flux horizontal sous-surfacique a été analysée lors de la seconde année après sa mise en opération. L’objectif de cette étude était d’évaluer la capacité épuratoire entre des bassins plantés par 5 espèces différentes de macrophytes et des bassins non-plantés. Malgré une eau faiblement chargée, représentative des eaux pluviales de la région de Shanghai, nous avons pu observer un meilleur pourcentage d’enlèvement dans les bassins plantés comparativement à ceux non-plantés et ce, pour l’ensemble des paramètres mesurés ; par exemple pour TN, l'efficacité médiane d'élimination des filtres non plantés était de 53% et de 76% pour les filtres plantés. Toutefois, aucune corrélation de performance épuratoire n’a été observée entre l’oxygène dissous (DO) et les paramètres qui y sont associés. Pour tous les paramètres mesurés (DCO, DBO5, NH3-N, TN et TP), la taille des bassins pourrait même être optimisée en considérant une surface totale correspondant au tiers de la superficie de départ (58 m2). Par contre, si d’autres objectifs de traitement étaient envisagés, tel que la réduction de pathogènes, la surface totale devrait possiblement être considérée et fait présentement l’objet de recherche

Neural tube patterning by Krox20 and emergence of a respiratory control.

International audienceRecent data begin to bridge the gap between developmental events controlling hindbrain neural tube regional patterning and the emergence of breathing behaviour in the fetus and its vital adaptive function after birth. In vertebrates, Hox paralogs and Hox-regulating genes orchestrate, in a conserved manner, the transient formation of developmental compartments in the hindbrain, the rhombomeres, in which rhythmic neuronal networks of the brainstem develop. Genetic inactivation of some of these genes in mice leads to pathological breathing at birth pointing to the vital importance of rhombomere 3 and 4 derived territories for maintenance of the breathing frequency. In chick embryo at E7, we investigated neuronal activities generated in neural tube islands deriving from combinations of rhombomeres isolated at embryonic day E1.5. Using a gain of function approach, we reveal a role of the transcription factor Krox20, specifying rhombomeres 3 and 5, in inducing a rhythm generator at the parafacial level of the hindbrain. The developmental genes selecting and regionally coordinating the fate of CNS progenitors may hold further clues to conserved aspects of neuronal network formation and function. However, the most immediate concern is to take advantage of early generated rhythmic activities in the hindbrain to pursue their downstream cellular and molecular targets, for it seems likely that it will be here that rhythmogenic properties will eventually take on a vital role at birth