Chromosomal control of pig populations in France: 2002-2006 survey

The chromosomal control of pig populations has been widely developed in France over the last ten years. By December 31st, 2006, 13 765 individuals had been karyotyped in our laboratory, 62% of these since 2002. Ninety percent were young purebred boars controlled before service in artificial insemination centres, and 3% were hypoprolific boars. So far, 102 constitutional structural chromosomal rearrangements (67 since 2002) have been described. Fifty-six were reciprocal translocations and 8 peri- or paracentric inversions. For the first time since the beginning of the programme and after more than 11 000 pigs had been karyotyped, one Robertsonian translocation was identified in 2005 and two others in 2006. The estimated prevalence of balanced structural chromosomal rearrangements in a sample of more than 7700 young boars controlled before service was 0.47%. Twenty-one of the 67 rearrangements described since 2002 were identified in hypoprolific boars. All were reciprocal translocations. Twelve mosaics (XX/XY in 11 individuals, XY/XXY in one individual) were also diagnosed. Two corresponded to hypoprolific boars, and three to intersexed animals. The results presented in this communication would justify an intensification of the chromosomal control of French and, on a broader scale, European and North-American pig populations

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Étude chromosomique et moléculaire de la sous-famille des Cervinae (application des résultats à la gestion des troupeaux en captivité d'espèces menacées)

La sous famille des Cervinae comporte 17 espèces et parmi ces espèces, plus de la moitié sont considérées comme menacées ou vulnérables suivant les critères de l'UICN. La systématique de cette sous-famille reste à discuter, notamment pour mieux définir les unités de conservation. Ce travail a pour objectifs : l'étude en cytogénétique classique et moléculaire des espèces de la sous famille des Cervinae, l'étude des relations phylogénétiques à l'aide des caractères chromosomiques et leur confrontation avec les données de génétique moléculaire, et l'étude génétique d'une population captive d'une espèce menacée Cervus Duvauceli dans la perspective d'un programme de réintroduction. Les travaux de cytogénétique classique et moléculaire ont permis de déterminer les homoéologies entre le caryotype de la vache et celui d'une sous-espèce de cerf sika (C. nippon pseudaxis). La différence entre les caryotypes des espèces de Cervinae consiste en une réduction du nombre de chromosomes par translocations robertsoniennes. La plupart des chromosomes impliqués ont pu être identifiés par rapport aux chromosomes bovins. Les caractères chromosomiques et moléculaires ont permis de confirmer que la sous famille des Cervinae est monophylétique. D'après les données moléculaires, le genre Cervus n'est pas monophylétique car Cervus duvauceli forme avec le genre Axis et Dama un groupe monophylétique séparé des autres espèces de Cervinae. L'étude de la population de cerfs de Duvaucel à l'aide de marqueurs microsatellites n'a pas permis de déterminer les liens exacts de parenté entre les individus. Le nombre d'individus fondateurs de cette population a été estimé. Cette population ne peut pour le moment pas être utilisée pour des actions de réintroduction car ni la sous-espèce ni l'absence d'hybrides n'ont pu être déterminées faute d'échantillons de référence.TOURS-BU Sciences Pharmacie (372612104) / SudocPARIS-Museum-Bib zoologie mam. (751052312) / SudocSudocFranceF

Exploring H3K27me3 dynamic at pericentromeric heterochromatin in mouse early embryo

International audienc

Histone remodeling reflects conserved mechanisms&nbsp;of bovine and human preimplantation&nbsp;development.

How histone modifications regulate changes in gene expression during preimplantation development in any species remains poorly understood. Using CUT&amp;Tag to overcome limiting amounts of biological material, we profiled two activating (H3K4me3 and H3K27ac) and two repressive (H3K9me3 and H3K27me3) marks in bovine oocytes, 2-, 4-, and 8-cell embryos, morula, blastocysts, inner cell mass, and trophectoderm. In oocytes, broad bivalent domains mark developmental genes, and prior to embryonic genome activation (EGA), H3K9me3 and H3K27me3 co-occupy gene bodies, suggesting a global mechanism for transcription repression. During EGA, chromatin accessibility is established before canonical H3K4me3 and H3K27ac signatures. Embryonic transcription is required for this remodeling, indicating that maternally provided products alone are insufficient for reprogramming. Last, H3K27me3 plays a major role in restriction of cellular potency, as blastocyst lineages are defined by differential polycomb repression and transcription factor activity. Notably, inferred regulators of EGA and blastocyst formation strongly resemble those described in humans, as opposed to mice. These similarities suggest that cattle are a better model than rodents to investigate the molecular basis of human preimplantation development

Histone remodeling reflects conserved mechanisms of bovine and human preimplantation development

International audienceHow histone modifications regulate changes in gene expression during preimplantation development in any species remains poorly understood. Using CUT&Tag to overcome limiting amounts of biological material, we profiled two activating (H3K4me3 and H3K27ac) and two repressive (H3K9me3 and H3K27me3) marks in bovine oocytes, 2-, 4-, and 8-cell embryos, morula, blastocysts, inner cell mass, and trophectoderm. In oocytes, broad bivalent domains mark developmental genes, and prior to embryonic genome activation (EGA), H3K9me3 and H3K27me3 co-occupy gene bodies, suggesting a global mechanism for transcription repression. During EGA, chromatin accessibility is established before canonical H3K4me3 and H3K27ac signatures. Embryonic transcription is required for this remodeling, indicating that maternally provided products alone are insufficient for reprogramming. Last, H3K27me3 plays a major role in restriction of cellular potency, as blastocyst lineages are defined by differential polycomb repression and transcription factor activity. Notably, inferred regulators of EGA and blastocyst formation strongly resemble those described in humans, as opposed to mice. These similarities suggest that cattle are a better model than rodents to investigate the molecular basis of human preimplantation development

Organisation du génome embryonnaire après la fécondation chez les mammifères

Chez les mammifères, le génome de l’embryon nouvellement fécondé est d’abord transcriptionnellement inactif. Le développement embryonnaire dépend alors strictement de l’héritage maternel en ARN et en protéines présents dans l’ovocyte et accumulés avant l’ovulation. La mise en route de l’expression des gènes embryonnaires se fait ultérieurement lors de la phase appelée « activation du génome embryonnaire (EGA) », à un moment de la période préimplantatoire variable selon les espèces. Cette phase d’activation est dépendante de la présence des composants de la machinerie transcriptionnelle de base mais aussi de l’évolution de l’organisation des génomes parentaux après la fécondation. En effet, au cours des premiers cycles embryonnaires, les noyaux subissent une réorganisation intense qui constituerait un élément clé dans la régulation du développement embryonnaire

Identification by R-banding and FISH of chromosome arms involved in Robertsonian translocations in several deer species

We constructed and analyzed the RBG-banded karyotype of five deer species: Chital (Axis axis), White-lipped deer (Cervus albirostris), Rusa deer (Cervus timorensis russa), Sambar deer (Cervus unicolor) and Eld's deer (Cervus eldi siamensis). Among these five species, only Eld's deer had been previously karyotyped using R-banding. In order to identify all the chromosome correspondences with cattle and precisely which chromosome arms are involved in Robertsonian translocations, we compared the karyotypes of these five species with those of the closely related and well-characterized species, cattle (Bos taurus) and Vietnamese Sika deer (Cervus nippon pseudaxis). Among these six deer species (the five above plus the Vietnamese Sika deer), we found thirteen different Robertsonian translocations involving nineteen different chromosome arms. Thirteen chromosome arms were identified by comparison of R-banding patterns only and the remaining six were either confirmed or identified by FISH-mapping of bovine or caprine probes previously localized in cattle. Finally, we observed that five of the thirteen Robertsonian translocations are shared by at least two species and that some chromosome arms are more frequently involved in Robertsonian translocations than others. (Résumé d'auteur

Antagonist Xist and Tsix co-transcription during mouse oogenesis and maternal Xist expression during pre-implantation development calls into question the nature of the maternal imprint on the X chromosome

International audienceDuring the first divisions of the female mouse embryo, the paternal X-chromosome is coated by Xist non-coding RNA and gradually silenced. This imprinted X-inactivation principally results from the apposition, during oocyte growth, of an imprint on the X-inactivation master control region: the X-inactivation center (Xic). This maternal imprint of yet unknown nature is thought to prevent Xist upregulation from the maternal X (XM) during early female development. In order to provide further insight into the XM imprinting mechanism, we applied single-cell approaches to oocytes and pre-implantation embryos at different stages of development to analyze the expression of candidate genes within the Xic. We show that, unlike the situation pertaining in most other cellular contexts, in early-growing oocytes, Xist and Tsix sense and antisense transcription occur simultaneously from the same chromosome. Additionally, during early development, Xist appears to be transiently transcribed from the XM in some blastomeres of late 2-cell embryos concomitant with the general activation of the genome indicating that XM imprinting does not completely suppress maternal Xist transcription during embryo cleavage stages. These unexpected transcriptional regulations of the Xist locus call for a re-evaluation of the early functioning of the maternal imprint on the X-chromosome and suggest that Xist/Tsix antagonist transcriptional activities may participate in imprinting the maternal locus as described at other loci subject to parental imprinting