Détermination et différenciation du sexe chez l'algue brune Ectocarpus

Genetic sex determination is usually controlled by sex chromosomes carrying a non-recombining sex-determining region (SDR). Despite the common origin of sex (meiosis) in Eukaryotes, the evolution of sex chromosomes has evolved repeatedly and independently. Our knowledge in sex chromosomes comes mainly from the analysis of diploid systems (XY and ZW sex chromosomes) in animals and land plants. However the recent genome sequencing of the brown alga Ectocarpus, not only opens up the possibility of studying sex chromosomes in a phylogenetic distant group but also of analysing a haploid sex chromosome system (UV sex chromosomes). Indeed in Ectocarpus sex is expressed during the haploid phase of the life cycle, where U and V sex chromosomes are restricted to female and male, respectively. The Ectocarpus sex chromosomes have some unusual evolutionary features such as the size of the non-recombining region, which is surprisingly small for a 70 million year old system. Also the evolutionary aspect of sexual dimorphism was studied by analyzing male and female transcriptomes and by identifying several subtle sexual dimorphic traits. Parthenogenetic capacity is a sexual dimorphic trait in some populations of Ectocarpus. The genetic link between parthenogenesis and sex was analysed and a locus that controls parthenogenetic was located to the Ectocarpus sex chromosome, in the recombining pseudoautosomal region. Fitness analysis strongly suggested that the parthenogenetic locus is a sexual antagonistic locusLe déterminisme génétique du sexe nécessite souvent l’évolution d’une région non-recombinante (NR) formant ainsi paire de chromosomes sexuels. Bien que la reproduction sexuée ait une origine commune à tous les eucaryotes, l’évolution des chromosomes sexuels s’est quant à elle effectuée de manière répétée et indépendante. Les chromosomes du sexe ont été particulièrement étudiés dans les systèmes diploïdes (chromosomes sexuels XY et ZW) des plantes et animaux. Le récent séquençage du génome d’Ectocarpus, modèle d’étude des algues brunes, donne non seulement une chance unique d’analyser les chromosomes sexuels dans un groupe phylogénétiquement distant des opisthocontes et de la lignée verte ; mais il donne aussi l’opportunité d’examiner un système haploïde de chromosomes sexuels (système UV). Chez Ectocarpus l’expression du sexe a lieu pendant la phase haploïde du cycle de vie, avec les chromosomes U et V, respectivement spécifiques aux femelles et aux mâles. L’analyse des chromosomes sexuels chez Ectocarpus a montré que la taille de la région NR est restée modeste pour un système vieux de plus de 70 millions d’années. Une analyse des dimorphismes sexuels a été effectuée ainsi que l’étude comparative des transcriptomes mâle et femelle d’Ectocarpus. Le développement parthénogénétique est, dans certaines populations d’Ectocarpus, un dimorphisme sexuel. Le lien génétique entre parthénogenèse et sexe a été analysé et suggère qu’un locus contrôlant la parthénogenèse est localisé au niveau de la partie recombinante du chromosome sexuel d’Ectocarpus. De plus, une analyse de fitness indique que le locus de la parthénogenèse est soumis à une sélection antagoniste entre les deux sexes

Sex determination and differentiation in the brown alga Ectocarpus

Le déterminisme génétique du sexe nécessite souvent l’évolution d’une région non-recombinante (NR) formant ainsi paire de chromosomes sexuels. Bien que la reproduction sexuée ait une origine commune à tous les eucaryotes, l’évolution des chromosomes sexuels s’est quant à elle effectuée de manière répétée et indépendante. Les chromosomes du sexe ont été particulièrement étudiés dans les systèmes diploïdes (chromosomes sexuels XY et ZW) des plantes et animaux. Le récent séquençage du génome d’Ectocarpus, modèle d’étude des algues brunes, donne non seulement une chance unique d’analyser les chromosomes sexuels dans un groupe phylogénétiquement distant des opisthocontes et de la lignée verte ; mais il donne aussi l’opportunité d’examiner un système haploïde de chromosomes sexuels (système UV). Chez Ectocarpus l’expression du sexe a lieu pendant la phase haploïde du cycle de vie, avec les chromosomes U et V, respectivement spécifiques aux femelles et aux mâles. L’analyse des chromosomes sexuels chez Ectocarpus a montré que la taille de la région NR est restée modeste pour un système vieux de plus de 70 millions d’années. Une analyse des dimorphismes sexuels a été effectuée ainsi que l’étude comparative des transcriptomes mâle et femelle d’Ectocarpus. Le développement parthénogénétique est, dans certaines populations d’Ectocarpus, un dimorphisme sexuel. Le lien génétique entre parthénogenèse et sexe a été analysé et suggère qu’un locus contrôlant la parthénogenèse est localisé au niveau de la partie recombinante du chromosome sexuel d’Ectocarpus. De plus, une analyse de fitness indique que le locus de la parthénogenèse est soumis à une sélection antagoniste entre les deux sexes.Genetic sex determination is usually controlled by sex chromosomes carrying a non-recombining sex-determining region (SDR). Despite the common origin of sex (meiosis) in Eukaryotes, the evolution of sex chromosomes has evolved repeatedly and independently. Our knowledge in sex chromosomes comes mainly from the analysis of diploid systems (XY and ZW sex chromosomes) in animals and land plants. However the recent genome sequencing of the brown alga Ectocarpus, not only opens up the possibility of studying sex chromosomes in a phylogenetic distant group but also of analysing a haploid sex chromosome system (UV sex chromosomes). Indeed in Ectocarpus sex is expressed during the haploid phase of the life cycle, where U and V sex chromosomes are restricted to female and male, respectively. The Ectocarpus sex chromosomes have some unusual evolutionary features such as the size of the non-recombining region, which is surprisingly small for a 70 million year old system. Also the evolutionary aspect of sexual dimorphism was studied by analyzing male and female transcriptomes and by identifying several subtle sexual dimorphic traits. Parthenogenetic capacity is a sexual dimorphic trait in some populations of Ectocarpus. The genetic link between parthenogenesis and sex was analysed and a locus that controls parthenogenetic was located to the Ectocarpus sex chromosome, in the recombining pseudoautosomal region. Fitness analysis strongly suggested that the parthenogenetic locus is a sexual antagonistic locu

Sleep disturbances in affective disorders

Sleep disturbances are an integral feature of affective disorders. Episodes of affective illness are often accompanied by marked changes in sleep. Insomnia frequently occurs in mania, and insomnia or hypersomnia often occurs in depression. The observation that sleep deprivation improves mood in about 50-60%of depressed subjects [1], and that it can even trigger mania in patients with bipolar disorder [2, 3], suggests a close relationship between the regulation of mood and the regulation of sleep. If we assume a neurobiological link between sleep and mood, the recent explosion of basic findings on the functional neuroanatomy of sleep-wake regulation and on the cellular basis of the different sleep rhythms [4-7] should open newways in our understanding of affective disorders. In the present review, we therefore propose to focus primarily on those findings that enable the integration of sleep-wake electrophysiological and neurobiological data observed in affective disorders with our present knowledge of the sleep-wake mechanisms.SCOPUS: ch.binfo:eu-repo/semantics/publishe

Statistical Decision Tree: A Tool for Studying Pharmaco-EEG Effects of CNS-Active Drugs

International audienceQuantitative pharmaco-EEG has become a useful technique for determing pharmacodynamic parameters after CNS-active drug administration. Nevertheless, one of the most important problems faced by practitioners of pharmaco-EEG is the difficulty in evaluating drug-specific effects. In this article, a methodology for comparing two time sequences of pharmacodynamic measurements, the Statistical Decision Tree (SDT), is proposed. This methodology, based on one- and multi-dimensional Wilcoxon signed-rank tests on EEG variables, takes into account vigilance fluctuations and placebo effects in order to pick out effects specifically due to the drug

Genetic and cellular characterization of parthenogenesis in the brown alga Ectocarpus

National audienc

Sleep microstructure around sleep onset differentiates major depressive insomnia from primary insomnia

In the present study we investigate whether alterations of sleep propensity or of wake propensity are implicated in sleep initiation disturbances encountered in major depressive insomnia and in primary insomnia. For this purpose, the time course of electroencephalogram (EEG) power density during the period preceding sleep onset and during the first non-rapid eye movement (REM) period was examined in three age and gender matched groups of 10 women and 11 men (healthy controls, primary insomniacs and depressive insomniacs). In contrast to healthy controls and depressive insomniacs, patients with primary insomnia did not experience a gradual decrease of their alpha and beta1 power during the sleep onset period and had a lower delta activity in the 5 min preceding sleep onset. Compared with the two other groups, depressive patients exhibit less dynamic changes in slow wave activity during the first non-REM period. The present results suggest that hyperarousal (high 'Process W') may mainly be implicated in the sleep initiation difficulties of primary insomniacs whereas the homeostatic sleep regulation process seems to be partially maintained. In our major depressed patients, the sleep initiation disturbances appeared to relate to a lower sleep pressure (low 'Process S') rather than to hyperarousal. This study supports the idea that different mechanisms are implicated in sleep disturbances experienced by primary insomniacs and major depressive insomniacs.SCOPUS: ar.jFLWINinfo:eu-repo/semantics/publishe

Origin and evolutionary trajectories of brown algal sex chromosomes

Sex chromosomes fall into three classes: XX/XY, ZW/ZZ and U/V systems. The rise, evolution and demise of U/V systems have remained enigmatic to date. Here, we analyze genomes spanning the entire brown algal phylogeny to decipher their sex-determination evolutionary history. The birth of U/V sex chromosomes evolved more than 250 million years ago, when a pivotal male-determinant located in a discrete region in proto-U and proto-V chromosomes ceased recombining. Over time, nested inversions led to step-wise expansions, accompanying increasing morphological complexity and sexual differentiation of brown seaweeds. Unlike XX/XY and ZW/ZZ, U/V evolve mainly by gene gain, showing minimal degeneration. They are structurally dynamic, and act as genomic ’cradles’ fostering the birth of new genes. Our analyses show that hermaphroditism arose from ancestral males that acquired U-specific genes by ectopic recombination, and that in the transition from a U/V to an XX/XY system, V-specific genes moved down the genetic hierarchy of sex determination. Both events lead to the demise of U and V and erosion of their specific genomic characteristics. Taken together, our findings offer a comprehensive model of U/V sex chromosome evolution. HIGHLIGHTS Sexes arose in brown algae due to ceased recombination of a male-determining gene-containing region U/V sex chromosomes evolve via gene gain and act as ‘cradles’ of genomic novelty Emergence of XX/XY chromosomes involved demotion of the V-master sex-determining gene Introgression of female-specific genes into a male background allowed hermaphroditism to aris

Assessing sleep architecture and continuity measures through the analysis of heart rate and wrist movement recordings in healthy subjects: comparison with results based on polysomnography

OBJECTIVE: The objective of the study was to evaluate the reliability of a new methodology for assessing sleep architecture descriptors based on heart rate and body movement recordings. METHODS: Twelve healthy male and female subjects between 18 and 40 years of age, without sleep disorders and not taking any drug or medication that could affect sleep, were recorded continuously during five consecutive nights. Together with the standard polysomnography, heart rate was recorded with a Holter and wrist movements by actimetry. Of the 60 recorded nights, 48 artifact-free nights were analyzed by two independent and well-trained visual scorers according to the rules of the American Academy of Sleep Medicine. Sleep stages were assigned to every 30-s epoch. In parallel, the same nights were analyzed by the new methodology using only heart rate and actimetry data, allowing a 1-s epoch sleep stage classification. Sleep architecture was measured for 48 nights, independently for the two manual scorings and the automatic analysis. RESULTS: Over 42 nights, the intra-class correlation coefficient, used to assess the consistency or reproducibility of quantitative measurements made by different observers, was classified as excellent when all 12 descriptors were combined. Analyses of the individual descriptors showed excellent interclass correlation for eight and good for four of the 12. CONCLUSION: The automatic analysis of heart rate and body movement during sleep allows for the evaluation of sleep architecture and continuity that is equivalent to those obtained by manual scoring of polysomnography. The technique used here is simple and robust to allow for home sleep monitoring