Proximity in chromatin : opportunities for innovations

Mammalian chromosomes extensively communicate with each other via long-range chromatin interactions. These interactions are mostly mediated by proteins, which work as teams to control genes in the cells. These interactions could also help to unravel the mechanisms of diseases such as cancer, from new perspectives. The packaging of the chromatin fiber and how it relates to epigenetic marks that regulate its accessibility to govern lineage-specific gene expression repertoires is currently the focus of immense efforts worldwide. Moreover, how chromosomes are hierarchically folded and how they relate to each other as well as to structural hallmarks of the nucleus is a largely unchartered territory in large cell populations not to mention in individual cells. This thesis has an emphasis on the analysis of pivotal chromatin features of single cells. Thus, interactions between a genome organizer termed CTCF and a factor involved in DNA repair, PARP1, could be demonstrated using the ISPLA technique. Such interactions likely underlie the formation of chromatin networks. Next, novel strategies/techniques were developed to visualize chromosomal structures and 3D networks by scoring for chromatin proximities within individual cells. One strategy included a novel method termed Chromatin In Situ Proximity (ChrISP) to visualize and identify proximities between chromatin fibers and other structural hallmarks in single cells at a resolution < 170 Å beyond that of the light microscope. Thus, large-scale changes in conformations of a single human chromosome upon the administration of reprogramming cues could be visualized. Finally, this innovation was further developed to explore differences in proximities of chromatin fibers that organize chromosome territories. The novel design, termed “rainbow ChrISP” translates physical distances in 3D, between chromatin fibres into different colors visualized with conventional microscope. This technique produced new insights into chromosome conformations and their regulation to enhance our understanding of their governing principles in single cells during development and disease

Multigeneration Effects of Chronic Exposure to Polycyclic Aromatic Hydrocarbons in Gulf Killifish (Fundulus grandis)

The goal of this study was to examine potential adaptation within two generations of Gulf killifish exposed to polycyclic aromatic hydrocarbons (PAH) while also investigating the use of mucus as an effective and non-lethal alternative to determine concentrations of 11-ketotestosterone (11-KT) and vitellogenin (VTG) of F. grandis. Multiple biomarkers were used to assess adaptation within these fish, such as lysozyme (enzyme critical in innate immunity), and 11-ketotestosterone and vitellogenin (endocrine hormones often affected by PAHs). Mucal concentrations of 11-KT and VTG were determined and evaluated for effectiveness through comparative assays with blood plasma. This method was then applied to evaluate potential endocrine disruptions in F. grandis undergoing chronic exposure to a water accommodated fraction (WAF) of crude oil. Both 11-KT and VTG showed significant positive relationships between their respective concentrations in the plasma and mucus. Four populations of F. grandis with different exposure histories were exposed to WAF for 60 days, and followed 40 additional days after WAF treatments. Concentrations of 11-KT in mucus decreased throughout the 40 day WAF exposure period when compared to responses within control treatment males. Exposure history of the populations also had a significant effect on observed 11-KT concentrations in mucus; exposed Gangs Bayou males (reference site) had a decrease in 11-KT concentrations, while concentrations of 11-KT of exposed males from Vince Bayou (superfund site) increased. Exposed females showed near null concentrations of mucosal VTG when exposed to WAF regardless of exposure history while control groups did not exhibit deceases in mucus VTG concentrations. The second portion of this thesis details the exposures of two successive generations of Gulf killifish first to WAF and the second to naphthalene. Sperm motility and oocyte cell wall thickness was significantly lower in adults exposed to WAF, while egg viability and survival activity index were not. For the resulting progeny, lysozyme assessed within the surface mucus of Gulf killifish with naphthalene exposure significantly decreasing the relative concentration of lysozyme regardless of parental history. Changes in concentrations of lysozyme were also significant with the linear relationship of time, treatment and parental history with individuals from exposed parents showing overall higher concentrations than individuals from control parents. EROD induction was significantly higher in fish exposed to naphthalene regardless of parental history. Results show potential alteration to PAH metabolism and immunology within two generations in Gulf killifish

L'Education à la Sexualité (ES) dans les établissements privés et publics au Liban

International audienceCe travail concerne une facette de l'état des lieux sur l'implémentation de l'éducation à la sexualité (ES) dans divers types d'établissements scolaires libanais : privés religieux, privés non confessionnels et publics. Il présente les résultats d'une enquête dans plus d'une centaine d'établissements pour savoir dans lesquels l'enseignement de ce thème est ou non, ou plus ou moins, mis en œuvre, et pour analyser les caractéristiques de cet enseignement quand il existe (classes et matières concernées, thèmes abordés,...). Des directeurs, des coordonnateurs et des enseignants de 104 établissements répartis selon les diverses zones géographiques du Liban ont répondu à un questionnaire. L'ensemble des analyses a montré, selon les établissements, certaines convergences et une diversité, sans corrélation significative avec le statut de l'établissement, portant sur le degré d'implémentation de l'ES, sur les cadres et les personnes les plus appropriés pour la mettre en œuvre. Les points de vue aussi bien convergents, que divergents, peuvent participer aux difficultés d'implémentation de l'ES dans le cadre scolaire libanais

Butterfly and skipper records from Lebanon (Lepidoptera: Papilionoidea)

Eighty-five specimens of 30 papilionoid species have been collected in Lebanon during entomological expeditions launched in 2015 and 2016 by the joint project of the Hungarian Natural History Museum and the Holy Spirit University of Kaslik. Th e collecting sites and events are listed, and the species annotated. With 23 figures

Etat des lieux de l'éducation à la sexualité dans les établissements privés et publics au Liban

Ce travail tente de tracer un état des lieux de l'éducation à la sexualité dans les divers établissements scolaires libanais : privés religieux, privés non confessionnels et publics. Il présente les résultats d'une enquête dans plus d'une centaine d'établissements divers pour savoir dans lesquels l'enseignement de ce thème est ou non, ou plus ou moins, mis en œuvre, et pour analyser les caractéristiques de cet enseignement quand il existe (classes et matières concernées, thèmes abordés,...). Des directeurs, des coordonnateurs et des enseignants de 104 établissements libanais répartis selon les diverses zones géographiques du Liban ont répondu à un questionnaire. L'ensemble des analyses a montré, selon les établissements, une diversité qui porte sur le degré d'implémentation de l'ES, sur sa définition, sur les cadres et les personnes les plus appropriés pour la mettre en œuvre. Cette diversité sans corrélation significative avec le statut de l'établissement peut constituer un obstacle à l'implémentation de l'ES dans le cadre scolaire libanais

Sex Education in Lebanon and France

International audienceThis work is a comparison between France and Lebanon. It analyzes the conceptions of Lebanese and French teachers on issues concerning human sexuality and its education. Our goal is to highlight the different conceptions of teachers in both countries and to identify the parameters to which these differences are correlated. All the multivariate analyses conducted show two very different systems of conceptions, very significantly differentiating Lebanese teachers' conceptions of French teachers ones. French teachers, unlike their Lebanese colleagues, are more conducive to early learning topics related to sexuality to students between 6 and 15 years old depending on the subject. They are more likely to accept abortion and homosexuality, to focus on safer sex as an attitude that can reduce the spread of AIDS, and to consider that the teaching of STIs is not only the issue of biology teachers. The differences between Lebanon and France are not reducible to religion: each country has its own identity rooted in its specific geographical, historical, economic and cultural context

Encapsulation of an antifungal agent within biodegradable polymers: composition effect

Polylactic acid and poly(lactic-co-glycolic acid) are two aliphatic polyesters commonly used in drug delivery systems. Having a hydrophobic nature, they could be used for the encapsulation of hydrophobic drugs such as Amphotericin B. Drug-loaded microspheres were prepared using solvent evaporation by changing the ratio of Polylactic acid to poly(lactic-co-glycolic acid) in the organic mixture. Results showed that higher drug encapsulation and drug loading values were seen for formulations having higher lactide content. This had also influenced the drug release rate which was slower at higher lactide percentage. Microspheres, which were spherical in shape and porous in structure, had homogeneous particles sizes ranging between 100 and 300 µm. At last, FT-IR spectra recorded in this study revealed a stable character of both polymer and drug after microencapsulation