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Introduction The wood frog, Rana sylvatica (Boreorana sylvatica), is one of the freeze-tolerant model organisms that survive sub-zero temperatures for several months. During freezing, the wood frog employs multiple adaptation [...], Rana sylvatica (also known as Boreorana sylvatica) is one of the few vertebrates that spend extreme winters showing no physiological signs of life. Up to 70% of the total body water of the wood frog freezes as extracellular ice. Survival in extreme conditions requires regulation at transcriptional and translational levels to activate prosurvival pathways. N6-methyladenosine ([m.sup.6]A) methylation is one of the most common RNA modifications, regulating transcript processing and translation by executing important functions that affect regulatory pathways in stress conditions. In the study, regulation of [m.sup.6]A-related proteins in the liver of R. sylvatica was analyzed during 24 h frozen and 8 h thaw conditions. Decreases in the activity of demethylases of 28.44 [+ or -] 0.4% and 24.1 [+ or -] 0.9% of control values in frozen and thaw tissues, respectively, were observed. Total protein levels of [m.sup.6]A methyltransferase complex components methyltransferase-like 14 and Wilm's tumor associated protein were increased by 1.28-fold and 1.42-fold, respectively, during freezing. Demethylase fat mass and obesity, however, showed a decreasing trend, with a significant decrease in abundance during recovery from frozen conditions. Levels of mRNA degraders YTHDF2 and YTHDC2 also decreased under stress. Overall, increased levels of [m.sup.6]A methylation complex components, and suppressed levels of readers/erasers, provide evidence for the potential role of RNA methylation in freezing survival and its regulation in a hypometabolic state. Key words: epigenetics, freeze tolerance, RNA methylation, metabolic rate depression, Rana sylvatica (Boreorana sylvatica)

Cutting-edge DNA methylation-based epigenetic aging techniques were applied to Gulf of Mexico northern red snapper (Lutjanus campechanus; n = 10; 1-26 years old) and red grouper (Epinephelus morio; n = 10; 2-14 years old). Bisulfiteconverted restriction site-associated DNA sequencing was used to identify CpG sites (cytosines followed by guanines) that exhibit age-correlated DNA methylation, and species-specific epigenetic clocks developed from hundreds of CpG sites in each species showed strong agreement between predicted and otolith-derived age [r.sup.2] > 0.99 for both species). Results suggest epigenetic age estimation could provide an accurate and efficient approach to mass-aging fishes in a non-invasive manner. Des methodes epigenetiques de pointe de determination de l'age reposant sur la methylation de l'ADN ont ete appliquees au vivaneau campeche (Lutjanus campechanus; n = 10; 1-26 ans) et au merou rouge (Epinephelus morio; n = 10; 2-14 ans). Le sequencage avec conversion au bisulfite d'ADN associe a des sites de restriction a ete utilise pour cerner des sites CpG (cytosines suivies de guanines) qui presentent une methylation de l'ADN correlee a l'age, et des horloges epigenetiques propres a l'espece developpees a partir de centaines de sites CpG de chaque espece ont revele de fortes concordances entre les ages predits et les ages obtenus par analyse d'otolites [r.sup.2] > 0,99 pour les deux especes). Les resultats donnent a penser que l'estimation epigenetique de l'age pourrait constituer une approche non invasive exacte et efficiente de determination des ages de quantites massives de poissons., Introduction Age data are fundamental to determining life history parameters (e.g., age-at-length, age-at-maturity, age-related fecundity) and are thus critical for fisheries assessment and management, particularly when age-structured stock assessment models [...]

Introduction Revealing the action of alcohol at the molecular level means a better understanding of the effects of alcohol on behavior (Ceccanti et al. 2015a, 2018a, 2018b; Coriale et al. [...], This work highlights recent studies in epigenetic mechanisms that play a role in alcoholism, which is a complex multifactorial disorder. There is a large body of evidence showing that alcohol can modify gene expression through epigenetic processes, namely DNA methylation and nucleosomal remodeling via histone modifications. In that regard, chronic exposure to ethanol modifies DNA and histone methylation, histone acetylation, and microRNA expression. The alcohol-mediated chromatin remodeling in the brain promotes the transition from use to abuse and addiction. Unravelling the multiplex pattern of molecular modifications induced by ethanol could support the development of new therapies for alcoholism and drug addiction targeting epigenetic processes. Key words: epigenetics, alcohol metabolism, DNA methylation, histone modifications, chromatin remodeling. Ce travail met en lumiere les etudes recentes des mecanismes epigenetiques qui jouent un role dans l'alcoolisme, une maladie complexe multifactorielle. De nombreuses preuves ont montre que l'alcool peut modifier l'expression genique au moyen de processus epigenetiques, a savoir la methylation d'ADN et le remodelage nucleosomique par les modifications d'histones. Dans cette veine, l'exposition chronique a l'alcool modifie l'ADN et la methylation des histones, l'acetylation des histones et l'expression de microARN. Le remodelage de la chromatine medie par l'alcool dans le cerveau favorise la transition de l'usage vers l'abus et la dependance. La resolution du patron multiplexe des modifications moleculaires induites par l'alcool implique la capacite de developper de nouvelles therapies de l'alcoolisme et de la dependance aux drogues qui ciblent les processus epigenetiques. [Traduit par la Redaction] Mots-cles: epigenetique, metabolisme de l'alcool, methylation d'ADN, modifications d'histones, remodelage de la chromatine.

Introduction A fundamental process in biological control is the passage of regulatory information from parental to progeny cells, during mitosis, to support cell fate and lineage commitment. While the mitotic [...], Epigenetic control is required to maintain competency for the activation and suppression of genes during cell division. The association between regulatory proteins and target gene loci during mitosis is a parameter of the epigenetic control that sustains the transcriptional regulatory machinery that perpetuates gene-expression signatures in progeny cells. The mitotic retention of phenotypic regulatory factors with cell cycle, cell fate, and tissue-specific genes supports the coordinated control that governs the proliferation and differentiation of cell fate and lineage commitment. Key words: cell cycle, nuclear microenvironment, gene expression, chromatin, Runx, intranuclear trafficking. Un niveau de controle epigenetique est requis afin de maintenir l'etat d'activation ou de suppression des genes lors de la division cellulaire. L'association de proteines regulatrices a des loci cibles lors de la mitose est un parametre du controle epigenetique qui aide la machinerie regulatrice de la transcription a maintenir le profil d'expression genique chez les cellules filles. Le maintien, au cours de la mitose, des facteurs de regulation phenotypiques avec les genes specifiques du cycle cellulaire, de la destinee cellulaire et des tissus appuie un controle coordonne qui regit la proliferation et la differenciation en lien avec la destinee cellulaire et l'engagement vers une lignee. Mots-cles : cycle cellulaire, microenvironnement nucleaire, expression genique, chromatine, Runx, trafic intranucleaire. [Traduit par la Redaction]

Introduction H2A.Z is a highly conserved variant of the canonical histone H2A. Its importance in eukaryotic cells is highlighted by the fact that it is essential for viability in organisms [...], The chromatin organization of a genome ultimately dictates the gene expression profile of the cell. It is now well recognized that key mechanisms that regulate chromatin structure include post-translational modifications of histones and the incorporation of histone variants at strategic sites within the genome. H2A.Z is a variant of H2A that is localized to the 5' end of many genes and is required for proper regulation of gene expression. However, its precise function in the transcription process is not yet well defined. In this review, we discuss some of the recent findings related to this histone variant, how it associates with other histone epigenetic marks, and how post-translational modifications of H2A.Z further define its function. Key words: histone, H2A.Z, chromatin, transcription, epigenetics. L'organisation d'un genome en chromatine dicte ultimement le profil d'expression genique de la cellule. On reconnait maintenant que les mecanismes cles qui reglent la structure de la chromatine comprennent les modifications posttraductionnelles des histones ainsi que l'incorporation de variants d'histones a des points strategiques du genome. La H2A.Z est un variant de l'histone H2A localise a l'extremite 5' de plusieurs genes et qui est requis a la regulation adequate de l'expression genique. Cependant, sa fonction precise dans le processus de la transcription n'est pas encore bien definie. Dans cet article de synthese, nous discutons de quelques resultats recents en lien avec ce variant d'histone, de la facon dont il s'associe avec d'autres marques epigenetiques reliees aux histones, et comment les modifications post- traductionnelles de la H2A.Z definissent davantage sa fonction. Mots-cles : histone, H2A.Z, chromatine, transcription, epigenetique. [Traduit par la Redaction]