Marqueur génétique | EPFL Graph Search

Le marqueur génétique est un gène ou une séquence polymorphe d'ADN aisément détectable grâce à un emplacement connu sur un chromosome. On peut l'utiliser en cartographie génétique pour « baliser » le génome et identifier des individus ou des espèces. Le marqueur génétique peut être décrit comme une variation (qui peut survenir en raison d'une mutation ou altération des loci génomiques) qui peut être observée. Un marqueur génétique peut être une séquence d'ADN courte, comme une séquence autour d'une seule paire de bases (single nucleotide polymorphism, SNP), ou de séquences répétées (VNTR), comme les minisatellites. Jusqu'en 1980, les marqueurs génétiques étaient morphologiques car basés uniquement sur des gènes polymorphes cartographiés à partir de l'analyse des phénotypes. Les nouvelles biotechnologies (PCR…) permettent une analyse directe du polymorphisme des séquences d'ADN pour dresser une carte génétique (marqueurs moléculaires -directement l'ADN - ou biochimiques). Typ

Tracking genes of ecological relevance using a genome scan in two independent regional population samples of Arabis alpina

Doris Herrmann, Pierre Taberlet

Understanding the genetic basis of adaptation in response to environmental variation is fundamental as adaptation plays a key role in the extension of ecological niches to marginal habitats and in ecological speciation. Based on the assumption that some genomic markers are correlated to environmental variables, we aimed to detect loci of ecological relevance in the alpine plant Arabis alpina L. sampled in two regions, the French (99 locations) and the Swiss (109 locations) Alps. We used an unusually large genome scan [825 amplified fragment length polymorphism loci (AFLPs)] and four environmental variables related to temperature, precipitation and topography. We detected linkage disequilibrium among only 3.5% of the considered AFLP loci. A population structure analysis identified no admixture in the study regions, and the French and Swiss Alps were differentiated and therefore could be considered as two independent regions. We applied generalized estimating equations (GEE) to detect ecologically relevant loci separately in the French and Swiss Alps. We identified 78 loci of ecological relevance (9%), which were mainly related to mean annual minimum temperature. Only four of these loci were common across the French and Swiss Alps. Finally, we discuss that the genomic characterization of these ecologically relevant loci, as identified in this study, opens up new perspectives for studying functional ecology in A. alpina, its relatives and other alpine plant species.

2010

Characterization of the Renin-Angiotensin System in Aged Cavernosal Tissue and its Role in Penile Fibrosis

Maiia Bragina, Babak Ebadi Shirmard, Fabiana Pereira Da Costa Fraga, Nikolaos Stergiopulos, Mikaël Nils Sturny

Background: The renin-angiotensin system (RAS) plays an important role in erectile function. The RAS contains 2 major axes: one deleterious, composed of ACE-Ang II-AT1 receptor, and another protective, composed of ACE2-Ang-(1-7)-Mas receptor. While aging is a well-known cause for development of male sexual disorders, little is known about local regulation of the RAS in age-related erectile dysfunction (ED). Aim: The present study aimed to assess regulation of the RAS in aging-associated ED rat model and evaluate possible options for disease management through pharmacological modulation of the RAS. Methods: Penile tissues were harvested from 3-, 12-, and 24-month-old Wistar rats. Local expression of major RAS components and ED markers was measured by RT-PCR. Protein expression of RAS components was assessed by western blot. Collagen deposition was measured by Sirius Red and immunohistochemical staining. Evaluation of collagen content was also performed in penile sections of Mas-knockout mice by Sirius Red and Masson's trichrome stainings. Finally, the effect of Ang-(1-7) pretreatment on TGF-beta-induced myofibroblast activation was studied in primary cavernosal and immortalized fibroblasts. Outcomes: Experimental results highlighted the essential role of the RAS in modulation of cavernosal fibrosis. Results: The present study demonstrates local expression of angiotensinogen mRNA alongside with major RAS components, which suggests local autonomous functioning of the RAS within penile tissue. Gene expression analysis revealed strong positive correlation between ACE-Ang II-AT1 axis with markers for inflammation and fibrosis. While corpus cavernosum from 24-month-old rats was characterized by increased collagen deposition, protein expression of ACE, AT1, and Mas was shown to be upregulated in the penile tissue of this group. At the same time, penile sections from Mas-knockout mice (FVB/N background) were also shown to have increased collagen deposition. Finally, it was demonstrated that Ang-(1-7) treatment of primary cavernosal and immor-talized fibroblasts was able to alleviate TGF-beta-induced fibroblast-to-myofibroblast transition. Clinical Translation: The present study suggests Ang-(1-7) treatment as a possible strategy for pharmacological management of fibrosis-associated ED in aging. Strengths & Limitations: The link between the RAS and penile fibrosis, indicated by a holistic screening of different ED markers, was confirmed by in vivo and in vitro data. However, results, presented in the manuscript, need to be further reinforced by human data. Important to note, the main goal of the study was to characterize RAS regulation in aging condition rather than state any causal relationships. Conclusion: Present study characterizes RAS regulation in aging-associated ED and indicates its important role in cavernosal fibrosis. Copyright (C) 2020, International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.

ELSEVIER SCI LTD2020

Microfluidic-assisted chromogenic in situ hybridization (MA-CISH) for fast and accurate breast cancer diagnosis

Léa Suzanne Bernier, Martinus Gijs, Huu Tuan Nguyen, Raphaël Etienne Jean Trouillon

Chromogenic in situ hybridization (CISH) is a common technique that is used for human epidermal growth factor receptor 2 (HER2) assessment in breast cancer diagnosis. CISH is based on the enzymatic amplification of DNA markers, generating a colorimetric image that can be visualized by a bright-field microscope and does not require a fluorescence detection setup. However, CISH is still characterized by a laborious and lengthy staining process, and is expensive due to the cost of the DNA probe solution. In this paper, we present a new technique named microfluidic-assisted chromogenic in situ hybridization (MA-CISH) in which hydrodynamic flow patterns in a microfluidic chip are used to improve hybridization efficiency between probe and target, thereby reducing the hybridization time and the consumption of probe solution. We optimized the MA-CISH protocol with a fractional factorial design of experiments using a SKBR3 breast cancer cell line. Optimized MA-CISH exploits discontinuous flow of DNA probe solution, enabling the reduction of the hybridization time from overnight down to 2 h and requiring 70% less probe solution, while achieving a better signal quality than the standard CISH technique. Optimized MA-CISH was successfully tested for several breast cancer tissue samples, showing a good correlation with standard CISH results as evaluated on adjacent slides. Finally, an automatic scoring software was developed to facilitate CISH signal evaluation, and showed good agreement with the traditional counting protocol.

Elsevier2017

Characterization of the Renin-Angiotensin System in Aged Cavernosal Tissue and its Role in Penile Fibrosis

Maiia Bragina, Babak Ebadi Shirmard, Fabiana Pereira Da Costa Fraga, Nikolaos Stergiopulos, Mikaël Nils Sturny

ELSEVIER SCI LTD2020