Microévolution des déterminismes sexuels chez le poisson Tétra Mexicain, Astyanax mexicanus

Sex determining (SD) mechanisms in teleost fishes have been investigated mainly at a macro-evolutionary scale highlighting a high turnover of master SD genes and their associated sex chromosomes. Interestingly, in addition to the A chromosomes, supernumerary B chromosomes (Bs) have been detected in a number of species and even associated as sex chromosomes in some of them. As such, my thesis project aimed to investigate SD mechanisms evolution with respect to these Bs in the Mexican tetra, Astyanax mexicanus, in which many blind cave populations (CF) are known to have evolved from a surface ancestral population (SF) less than 20,000 years. Our results provide functional evidences for the existence of an "unusual" SD system relying solely on male-dominant "B-sex" chromosomes with the gdf6b-B gene as a potential MSD gene in the Pachón CF. Furthermore, we also provide results suggesting a rapid evolutionary transition from a fixed male-dominant B-sex chromosome-type system in some populations toward a complex (probably polygenic) SD system relying only partly on the B-sex chromosome and their gdf6b-B loci in other populations.L’évolution des mécanismes de détermination du sexe (SD), qui a souvent été abordée principalement dans un contexte macro-évolutif chez les poissons, montre une variabilité saisissante des gènes SD et de leurs chromosomes sexuels associés. En plus des chromosomes de type A, certaines espèces de poissons téléostéens contiennent des chromosomes B (Bs), qui sont parfois considérés comme des chromosomes sexuels. À ce titre, mon projet de thèse avait pour objectif d’explorer l’évolution des systèmes SD en lien avec les Bs chez le tétra Mexicain, Astyanax mexicanus, qui comporte de nombreuses populations cavernicoles (CF) ayant évoluées à partir d'une population ancestrale de surface (SF) il y a moins de 20 000 ans. Nos travaux apportent des preuves fonctionnelles de l’existence d’un système de SD “original” reposant uniquement sur des chromosomes “B-sexuels” à dominance mâle avec gdf6b-B comme potentiel gène déterminant majeur du sexe chez les CF de la grotte Pachón. En parallèle, nous apportons des résultats qui suggèrent qu’il pourrait exister une transition évolutive rapide entre un système de type B-sex chromosome à dominance mâle fixe chez certaines populations vers un système plus complexe (probablement polygénique) ne reposant que partiellement sur le chromosome “B-sexuel” et ses loci gdf6b-B chez d’autres populations

Microevolution of sex determining mechanisms in the Mexican tetra, Astyanax mexicanus

L’évolution des mécanismes de détermination du sexe (SD), qui a souvent été abordée principalement dans un contexte macro-évolutif chez les poissons, montre une variabilité saisissante des gènes SD et de leurs chromosomes sexuels associés. En plus des chromosomes de type A, certaines espèces de poissons téléostéens contiennent des chromosomes B (Bs), qui sont parfois considérés comme des chromosomes sexuels. À ce titre, mon projet de thèse avait pour objectif d’explorer l’évolution des systèmes SD en lien avec les Bs chez le tétra Mexicain, Astyanax mexicanus, qui comporte de nombreuses populations cavernicoles (CF) ayant évoluées à partir d'une population ancestrale de surface (SF) il y a moins de 20 000 ans. Nos travaux apportent des preuves fonctionnelles de l’existence d’un système de SD “original” reposant uniquement sur des chromosomes “B-sexuels” à dominance mâle avec gdf6b-B comme potentiel gène déterminant majeur du sexe chez les CF de la grotte Pachón. En parallèle, nous apportons des résultats qui suggèrent qu’il pourrait exister une transition évolutive rapide entre un système de type B-sex chromosome à dominance mâle fixe chez certaines populations vers un système plus complexe (probablement polygénique) ne reposant que partiellement sur le chromosome “B-sexuel” et ses loci gdf6b-B chez d’autres populations.Sex determining (SD) mechanisms in teleost fishes have been investigated mainly at a macro-evolutionary scale highlighting a high turnover of master SD genes and their associated sex chromosomes. Interestingly, in addition to the A chromosomes, supernumerary B chromosomes (Bs) have been detected in a number of species and even associated as sex chromosomes in some of them. As such, my thesis project aimed to investigate SD mechanisms evolution with respect to these Bs in the Mexican tetra, Astyanax mexicanus, in which many blind cave populations (CF) are known to have evolved from a surface ancestral population (SF) less than 20,000 years. Our results provide functional evidences for the existence of an "unusual" SD system relying solely on male-dominant "B-sex" chromosomes with the gdf6b-B gene as a potential MSD gene in the Pachón CF. Furthermore, we also provide results suggesting a rapid evolutionary transition from a fixed male-dominant B-sex chromosome-type system in some populations toward a complex (probably polygenic) SD system relying only partly on the B-sex chromosome and their gdf6b-B loci in other populations

Implementation of third-order sliding mode for power control and maximum power point tracking in DFIG-based wind energy systems

In the field of generation systems, system performance, and power quality are greatly affected by traditional control techniques based on proportional-integral (PI) controllers, which are affected by internal and external factors. Wind power conversion systems based on doubly-fed induction generators are exposed to certain nonlinearities, uncertainties, and external disturbances. From another side, the extraction of the mechanical wind energy required a high-performance control system. This study proposes a robust nonlinear chattering-free third-order sliding mode control (TOSMC) based power control applied to fix its primary disadvantages which are the chattering phenomena and active and reactive power ripples. To show the potential of the proposed TOSMC control, a comparison study considering the TOSMC control, traditional sliding mode control, and the other existing controls is done in terms of power ripples, harmonic distortion of stator current, robustness, and response time. To ensure maximum power extractions and to protect the system, the maximum point power tracking technique based on TOSMC and the proposed control are also implemented. In addition, These techniques are used to control the stator powers. Finally, simulations (using Matlab software) are performed using different wind speeds with durability testing. The simulated results show that the proposed TOSMC control with the MPPT-TOSMC technique in this paper achieves satisfactory results in terms of reducing power ripples, response time, and harmonic distortion of stator current compared to the sliding mode control, where the harmonic distortion reduction ratio of the current was (50.24%) and the active power ripple reduction ratio (47.50%) and the reactive power (46.68%)

Eye Development in Sepia officinalis Embryo: What the Uncommon Gene Expression Profiles Tell Us about Eye Evolution

International audienceIn metazoans, there is a remarkable diversity of photosensitive structures; their shapes, physiology, optical properties, and development are different. To approach the evolution of photosensitive structures and visual function, cephalopods are particularly interesting organisms due to their most highly centralized nervous system and their camerular eyes which constitute a convergence with those of vertebrates. The eye morphogenesis in numerous metazoans is controlled mainly by a conserved Retinal Determination Gene Network (RDGN) including pax, six, eya, and dac playing also key developmental roles in non-retinal structures and tissues of vertebrates and Drosophila. Here we have identified and explored the role of Sof-dac, Sof-six1/2, Sof-eya in eye morphogenesis, and nervous structures controlling the visual function in Sepia officinalis. We compare that with the already shown expressions in eye development of Sof-otx and Sof-pax genes. Rhodopsin is the pigment responsible for light sensitivity in metazoan, which correlate to correlate visual function and eye development. We studied Sof-rhodopsin expression during retina differentiation. By in situ hybridization, we show that (1) all of the RDGN genes, including Sof-pax6, are expressed in the eye area during the early developmental stages but they are not expressed in the retina, unlike Sof-otx, which could have a role in retina differentiation; (2) Sof-rhodopsin is expressed in the retina just before vision gets functional, from stage 23 to hatching. Our results evidence a role of Sof-six1/2, Sof-eya, and Sof-dac in eye development. However, the gene network involved in the retinal photoreceptor differentiation remains to be determined. Moreover, for the first time, Sof-rhodopsin expression is shown in the embryonic retina of cuttlefish suggesting the evolutionary conservation of the role of rhodopsin in visual phototransduction within metazoans. These findings are correlated with the physiological and behavioral observations suggesting that S. officinalis is able to react to light stimuli from stage 25 of organogenesis on, as soon as the first retinal pigments appear

Micro-evolution of sex determination mechanisms and sex determining genes in the cavefish Astyanax mexicanus

Micro-evolution of sex determination mechanisms and sex determining genes in the cavefish Astyanax mexicanus. 1. European Symposium on Sex Determination in Vertebrate

Micro-evolution of sex determination mechanisms and sex determining genes in the cavefish, Astyanax mexicanus

Micro-evolution of sex determination mechanisms and sex determining genes in the cavefish, Astyanax mexicanus. Journées Scientifiques de l'Ecole Doctorale Ecologie Géosciences Agronomie Alimentation (ED EGAAL

Micro-evolution of sex determination mechanisms and sex determining genes in the cavefish, Astyanax mexicanus

Micro-evolution of sex determination mechanisms and sex determining genes in the cavefish, Astyanax mexicanus. 6. Annual Cavefish Meetin

Pre-hatching fluoxetine-induced neurochemical, neurodevelopmental, and immunological changes in newly hatched cuttlefish

WOS:000373609300007International audienceEmbryonic and early postembryonic development of the cuttlefish Sepia officinalis (a cephalopod mollusk) occurs in coastal waters, an environment subject to considerable pressure from xenobiotic pollutants such as pharmaceutical residues. Given the role of serotonin in brain development and its interaction with neurodevelopmental functions, this study focused on fluoxetine (FLX), a selective serotonin reuptake inhibitor (SSRI, antidepressant). The goal was to determine the effects of subchronic waterborne FLX exposure (1 and 10 mu g L-1) during the last 15 days of embryonic development on neurochemical, neurodevelopmental, behavioral, and immunological endpoints at hatching. Our results showed for the first time that organic contaminants, such as FLX, could pass through the eggshell during embryonic development, leading to a substantial accumulation of this molecule in hatchlings. We also found that FLX embryonic exposure (1 and 10 mu g L-1) (1) modulated dopaminergic but not serotonergic neurotransmission, (2) decreased cell proliferation in key brain structures for cognitive and visual processing, (3) did not induce a conspicuous change in camouflage quality, and (4) decreased lysozyme activity. In the long term, these alterations observed during a critical period of development may impair complex behaviors of the juvenile cuttlefish and thus lead to a decrease in their survival. Finally, we suggest a different mode of action by FLX between vertebrate and non-vertebrate species and raise questions regarding the vulnerability of early life stages of cuttlefish to the pharmaceutical contamination found in coastal waters

Micro-evolution of sex determination mechanisms and sex determining genes in the cavefish Astyanax mexicanus

In vertebrates, a remarkable diversity of sex determining mechanisms is observed, ranging from environmental to genetic sex determination (ESD and GSD). In teleosts, sex determination mechanisms include both environmental and genetic regulation and are extremely diverse, changeable, and labile. In addition, many sex-determining genes have been already found in this group of vertebrates showing that SD genes can be extremely variable even between closely related organisms. Hence, teleost fish have emerged as interesting models to study the macroevolution of sex determining (SD) mechanisms within vertebrates. The cavefish Astyanax mexicanus belongs to the Characiform group. Different populations of Astyanax have been described, including pigmented river-dwelling and several depigmented blind cave populations. These populations are still inter-fertile and cave populations are known to have evolved from a surface ancestral population around 100,000 years ago. In addition these Astyanax populations can be also reared under laboratory conditions quite easily and are amendable to genetic manipulations. Altogether this makes surface and cave populations a particularly interesting evolutionary genetic model system for comparative and microevolution studies. We thus initiated studies on the microevolution of SD and SD genes in the cavefish Astyanax mexicanus, and used restriction site-associated DNA (RAD) sequencing and pool-sequencing approaches to identify sex-biased molecular markers in both cave and surface populations. Our first results led to the identification of a candidate master sex-determining gene that potentially triggers SD in both cave and surface populations. Despite this conservation of a strict GSD and the same master sex-determining gene, our results also pin point that SD in Astyanax mexicanus has already evolved between surface and cave populations and suggest a quick evolutionary transition between an old polygenic SD system in surface population towards a more recent and simple monofactorial system in cave population