Contribution à la caractérisation des épilepsies canines et à son utilisation en tant que modèle des épilepsies humaines

LYON1-BU Santé (693882101) / SudocTOULOUSE-EN Vétérinaire (315552301) / SudocSudocFranceF

Meiotic recombination is confirmed to be unusually high in the fission yeast Schizosaccharomyces pombe

In most eukaryotes, meiotic crossovers (COs) are limited to 1–3 per chromosome, and are prevented from occurring close to one another by CO interference. The fission yeast Schizosaccharomyces pombe,an exception to these general rules, was reported to have the highest CO number per chromosome and no or weak interference. However, global CO frequency was indirectly estimated, calling for confirmation. Here, we used an innovative strategy to determine COs genome-wide in S. pombe. We confirmed weak CO interference, acting at physical distances compatible with the patterning of recombination precursors. We revealed a slight co-variation in CO number between chromosomes, suggesting that a limiting pro-CO factor varies between meiocytes. CO number per chromosome varies proportionally with chromosome size, with the three chromosomes having, on average, 15.9, 12.5, and 7.0 COs, respectively. This reinforces S. pombe’s status as the eukaryote with the highest CO number per chromosome described to date

Characterization of GnRH-related peptides from the Pacific oyster Crassostrea gigas.

International audienceGonadotropin-releasing hormone (GnRH), a key neuropeptide regulating reproduction in vertebrates has now been characterized in a number of non-vertebrate species. Despite the demonstration of its ancestral origin, the structure and the function of this family of peptides remain poorly known in species as distant as lophotrochozoans. In this study, two GnRH-related peptides (Cg-GnRH-a and CgGnRH-G) were characterized by mass spectrometry from extracts of the visceral ganglia of the Pacific oyster Crassostrea gigas. These peptides showed a high degree of sequence identity with GnRHs of other mollusks and annelids and to a lesser extent with those of vertebrates or with AKH and corazonins of insects. Both the mature peptides and the transcript encoding the precursor protein were exclusively expressed in the visceral ganglia. Significant differences in transcriptional activity of Cg-GnRH encoding gene were recorded in the ganglia along the reproductive cycle and according to trophic conditions with a higher level in fed animals compared to starved animals. This suggests the involvement of Cg-GnRHs as synchronizers of nutritional status with energy requirements during reproduction in oyster. Evidence for a role of Cg-GnRHs as neuroregulators and as neuroendocrine factors in bivalve is discussed

Inferring alteration conditions on Mars: Insights from near-infrared spectra of terrestrial basalts altered in cold and hot arid environments

International audienceCan information on the Martian environmental conditions prevailing during the alteration of its basaltic crust be inferred from near-infrared (NIR) spectra? In order to determine whether basalts altered under arid conditions but different temperatures have different spectral signatures, NIR spectra of basalts altered in cold (Udokan volcanic field, Siberia) and hot (Ogaden Basin, Ethiopia) environments were obtained. The NIR spectra of the alteration rind surface and the internal part of the studied samples are similar, suggesting that the NIR spectra of Martian bulk rocks may be of limited help in identifying paleoenvironment conditions. Bulk rock spectra analysis reveals, however, that spectra of the least altered rocks display clear absorption bands of smectites, suggesting that a distinction between clay minerals in weakly weathered basalts and clay-rich formations cannot be based solely on analysis of infrared spectra obtained from orbit. Additional compositional information can be retrieved from rock powder spectra – zeolites present in the Udokan basalt spectra might be used to infer composition and temperature of the fluids from which they precipitated. The presence of calcite and iddingsite is ascertained by other methods, but they are not apparent in bulk rock spectra and only weakly apparent in powder spectra. The basalt samples studied display alteration products that reflect their different alteration histories; nevertheless no criterion has been found that would help in identifying the origin of the weathering water – subsurface, rainfall, or snowfall

Interplay between boron doping and epitaxial relationships in VO 2 films grown by laser ablation

In this contribution, the effect of boron doping on the functional and structural properties of VO2 thin films is investigated. Temperature-dependent measurements were performed on pure and boron-doped (0.5 and 1.3 at.%) VO2 films grown on Al2O3(0001) by Reactive Pulsed Laser Deposition. Increasing the boron concentration leads to a noticeable decrease of the transition temperature (by ∼12°C), accompanied by a significant modification of the hysteresis loop shapes. The phase transition occurs at ca. 73 °C in the undoped film, while it drops down to ca. 60 °C in the film containing the highest boron amount. The undoped sample exhibits the best resistivity contrast (about 4 orders of magnitude) with a relatively narrow hysteresis cycle (∼ 6 °C). The most doped sample has a broad and significantly reduced resistivity contrast (less than 3 orders of magnitude). Raman spectroscopy and high-resolution X-ray diffraction were performed to elucidate the nature of the involved phases and their structure. A correlation was found between increasing the boron concentration and the formation of two peculiar in-plane epitaxial relationships; the VO2 films evolving from one to the other. We also evidenced the presence of the transient M2 phase in the most doped sample

Interplay between boron doping and epitaxial relationships in VO 2 films grown by laser ablation

In this contribution, the effect of boron doping on the functional and structural properties of VO2 thin films is investigated. Temperature-dependent measurements were performed on pure and boron-doped (0.5 and 1.3 at.%) VO2 films grown on Al2O3(0001) by Reactive Pulsed Laser Deposition. Increasing the boron concentration leads to a noticeable decrease of the transition temperature (by ∼12°C), accompanied by a significant modification of the hysteresis loop shapes. The phase transition occurs at ca. 73 °C in the undoped film, while it drops down to ca. 60 °C in the film containing the highest boron amount. The undoped sample exhibits the best resistivity contrast (about 4 orders of magnitude) with a relatively narrow hysteresis cycle (∼ 6 °C). The most doped sample has a broad and significantly reduced resistivity contrast (less than 3 orders of magnitude). Raman spectroscopy and high-resolution X-ray diffraction were performed to elucidate the nature of the involved phases and their structure. A correlation was found between increasing the boron concentration and the formation of two peculiar in-plane epitaxial relationships; the VO2 films evolving from one to the other. We also evidenced the presence of the transient M2 phase in the most doped sample

Beneficial micro-organisms for corals (BMC) health investigation within Porites astreoides dominant caribbean coral reef species microbiome

International audienc

Beneficial micro-organisms for corals (BMC) health investigation within Porites astreoides dominant caribbean coral reef species microbiome

International audienc

Beneficial micro-organisms for corals (BMC) health investigation within Porites astreoides dominant caribbean coral reef species microbiome

International audienc

Differential Effects of Bisphenol A and Diethylstilbestrol on Human, Rat and Mouse Fetal Leydig Cell Function

International audienceEndocrine disruptors (ED) have been incriminated in the current increase of male reproductive alterations. Bisphenol A (BPA) is a widely used weak estrogenic environmental ED and it is debated whether BPA concentrations within the average internal exposure are toxic. In the present study we investigated the effects of 10(-12) to 10(-5) M BPA concentrations on fetal Leydig cell function, as fetal life is a critical period of sensitivity to ED effects on male reproductive function. To this aim, fetal testes from human at 6.5-10.5 gestational weeks (GW) or from rat and mouse at a comparable critical period of development (14.5 days post-coitum (dpc) for rat and 12.5 dpc for mouse) were explanted and cultured using our validated organotypic culture system in the presence or absence of BPA for 1-3 days. BPA concentrations as low as 10(-8) M reduced testosterone secretion by human testes from day 1 of culture onwards, but not by mouse and rat testes where concentrations equal to 10(-5) M BPA were required. Similarly, 10(-8) M BPA reduced INSL3 mRNA levels only in human cultured testes. On the contrary, 10(-5) and 10(-6) M diethylstilbestrol (DES), a classical estrogenic compound, affected testosterone secretion only in rat and mouse testis cultures, but not in human testis cultures. Lastly, contrarily to the DES effect, the negative effect of BPA on testosterone produced by the mouse fetal testis was maintained after invalidation of estrogen receptor alpha (ER alpha). In conclusion, these results evidenced i) a deleterious effect of BPA on fetal Leydig cells function in human for concentrations from 10(-8) M upwards, ii) species-specific differences raising concerns about extrapolation of data from rodent studies to human risk assessment, iii) a specific signaling pathway for BPA which differs from the DES one and which does not involve ER alpha