Interpreting the genomic landscape of speciation: a road map for finding barriers to gene flow

Speciation, the evolution of reproductive isolation among populations, is continuous, complex, and involves multiple, interacting barriers. Until it is complete, the effects of this process vary along the genome and can lead to a heterogeneous genomic landscape with peaks and troughs of differentiation and divergence. When gene flow occurs during speciation, barriers restricting gene flow locally in the genome lead to patterns of heterogeneity. However, genomic heterogeneity can also be produced or modified by variation in factors such as background selection and selective sweeps, recombination and mutation rate variation, and heterogeneous gene density. Extracting the effects of gene flow, divergent selection and reproductive isolation from such modifying factors presents a major challenge to speciation genomics. We argue one of the principal aims of the field is to identify the barrier loci involved in limiting gene flow. We first summarize the expected signatures of selection at barrier loci, at the genomic regions linked to them and across the entire genome. We then discuss the modifying factors that complicate the interpretation of the observed genomic landscape. Finally, we end with a road map for future speciation research: a proposal for how to account for these modifying factors and to progress towards understanding the nature of barrier loci. Despite the difficulties of interpreting empirical data, we argue that the availability of promising technical and analytical methods will shed further light on the important roles that gene flow and divergent selection have in shaping the genomic landscape of speciation

L'huile essentielle de lavande pour induire la puberté chez la cochette ?

En élevage biologique, l'utilisation d'hormones de synthèse pour la gestion de la reproduction est interdite. Ainsi, des méthodes alternatives permettant de mieux organiser les périodes de mises-bas et donc le travail sur l'élevage sont envisageables, comme l'effet mâle. Toutefois, ce dernier est peu efficace en élevage porcin. Une équipe de recherche de l'Inra s'est penchée sur l'utilisation d'huile essentielle de lavande pour induire la puberté ou le premier œstrus chez des cochettes, avec ou sans présence d'un verrat. Les résultats montrent l'apparition d'œstrus plus précoces dans le lot de cochettes soumis à une pulvérisation d'huile essentielle de lavande à 170 jours d'âge. Ils devront être confirmés par des travaux complémentaires

Superior vena cava isolation using a pentaspline pulsed-field ablation catheter : feasibility and safety in patients undergoing atrial fibrillation catheter ablation

AIMS: Superior vena cava (SVC) isolation during atrial fibrillation catheter ablation is limited by the risk of collateral damage to the sinus node and/or the phrenic nerve. Due to its tissue-specificity, we hypothesized the feasibility and safety of pulsed-field ablation (PFA)-based SVC isolation.METHODS AND RESULTS: One hundred and five consecutive patients undergoing PFA-based AF catheter ablation were prospectively included. After pulmonary vein isolation (±posterior wall isolation and electrical cardioversion), SVC isolation was performed using a standardized workflow. Acute SVC isolation was achieved in 105/105 (100%) patients after 6 ± 1 applications. Transient phrenic nerve stunning occurred in 67/105 (64%) patients but without phrenic nerve palsy at the end of the procedure and at hospital discharge. Transient high-degree sinus node dysfunction occurred in 5/105 (4.7%) patients, with no recurrence at the end of the procedure and until discharge. At the 3-month follow-up visit, no complication occurred.CONCLUSION: SVC isolation using a pentaspline PFA catheter is feasible and safe.</p

Superior vena cava isolation using a pentaspline pulsed-field ablation catheter:feasibility and safety in patients undergoing atrial fibrillation catheter ablation

AIMS: Superior vena cava (SVC) isolation during atrial fibrillation catheter ablation is limited by the risk of collateral damage to the sinus node and/or the phrenic nerve. Due to its tissue-specificity, we hypothesized the feasibility and safety of pulsed-field ablation (PFA)-based SVC isolation.METHODS AND RESULTS: One hundred and five consecutive patients undergoing PFA-based AF catheter ablation were prospectively included. After pulmonary vein isolation (±posterior wall isolation and electrical cardioversion), SVC isolation was performed using a standardized workflow. Acute SVC isolation was achieved in 105/105 (100%) patients after 6 ± 1 applications. Transient phrenic nerve stunning occurred in 67/105 (64%) patients but without phrenic nerve palsy at the end of the procedure and at hospital discharge. Transient high-degree sinus node dysfunction occurred in 5/105 (4.7%) patients, with no recurrence at the end of the procedure and until discharge. At the 3-month follow-up visit, no complication occurred.CONCLUSION: SVC isolation using a pentaspline PFA catheter is feasible and safe.</p

Evaluation of an optimal preparation of human standardized fecal inocula for in vitro fermentation studies

This study investigated the optimal preservation approach to prepare human feces as inoculum for in vitro fermentations as an alternative to the use of fresh feces. The four treatments studied were: Treatment 1) fresh feces resuspended in dialysate solution + glycerol; Treatment 2) fresh feces resuspended in dialysate solution + glycerol and then stored at -80 degrees C; Treatment 3) fecal sample frozen with 15 g glycerol; and Treatment 4) fecal sample frozen. All the treatments contained 8.75 g of feces, 3.5 ml dialysate and 4.9 ml glycerol when inoculated in TIM-2 in vitro system. Treatment 1 (fresh fecal preparation) was used as a reference. The effects were evaluated in terms of i) metabolic activity and ii) composition of the microbiota using fermentation experiments in the TIM-2 in vitro system. In all treatments, high levels of acetate were produced followed by n-butyrate and propionate. However, the metabolic activity of the bacteria, in terms of short-chain fatty acid production, was affected by the different treatments. Microbiota composition was analyzed using the IS-pro profiling technique. Diversity in Actinobacteria, Firmicutes, Fusobacteria and Verrucomicrobia and Proteobacteria groups seemed to be preserved in all treatments whereas. it was observed to decline in the Bacteroidetes group. Preparing a human fecal inoculum resuspended in dialysate solution with glycerol and then stored at 80 degrees C showed high similarities to the results obtained with fresh feces, and is proposed as the optimal way to freeze fecal material as an alternative to fresh feces for in vitro fermentation studies