Molecular Brightness Approach for FRET Analysis of Donor-Linker-Acceptor Constructs at the Single Molecule Level: A Concept

In this report, we have developed a simple approach using single-detector fluorescence autocorrelation spectroscopy (FCS) to investigate the Förster resonance energy transfer (FRET) of genetically encoded, freely diffusing crTC2.1 (mTurquoise2.1-linker-mCitrine) at the single molecule level. We hypothesize that the molecular brightness of the freely diffusing donor (mTurquoise2.1) in the presence of the acceptor (mCitrine) is lower than that of the donor alone due to FRET. To test this hypothesis, the fluorescence fluctuation signal and number of molecules of freely diffusing construct were measured using FCS to calculate the molecular brightness of the donor, excited at 405 nm and detected at 475/50 nm, in the presence and absence of the acceptor. Our results indicate that the molecular brightness of cleaved crTC2.1 in a buffer is larger than that of the intact counterpart under 405-nm excitation. The energy transfer efficiency at the single molecule level is larger and more spread in values as compared with the ensemble-averaging time-resolved fluorescence measurements. In contrast, the molecular brightness of the intact crTC2.1, under 488 nm excitation of the acceptor (531/40 nm detection), is the same or slightly larger than that of the cleaved counterpart. These FCS-FRET measurements on freely diffusing donor-acceptor pairs are independent of the precise time constants associated with autocorrelation curves due to the presence of potential photophysical processes. Ultimately, when used in living cells, the proposed approach would only require a low expression level of these genetically encoded constructs, helping to limit potential interference with the cell machinery

Evaluation of polygenic risk scores for breast and ovarian cancer risk prediction in BRCA1 and BRCA2 mutation carriers

Background: Genome-wide association studies (GWAS) have identified 94 common single-nucleotide polymorphisms (SNPs) associated with breast cancer (BC) risk and 18 associated with ovarian cancer (OC) risk. Several of these are also associated with risk of BC or OC for women who carry a pathogenic mutation in the high-risk BC and OC genes BRCA1 or BRCA2. The combined effects of these variants on BC or OC risk for BRCA1 and BRCA2 mutation carriers have not yet been assessed while their clinical management could benefit from improved personalized risk estimates. Methods: We constructed polygenic risk scores (PRS) using BC and OC susceptibility SNPs identified through population-based GWAS: for BC (overall, estrogen receptor [ER]-positive, and ER-negative) and for OC. Using data from 15 252 female BRCA1 and 8211 BRCA2 carriers, the association of each PRS with BC or OC risk was evaluated using a weighted cohort approach, with time to diagnosis as the outcome and estimation of the hazard ratios (HRs) per standard deviation increase in the PRS. Results: The PRS for ER-negative BC displayed the strongest association with BC risk in BRCA1 carriers (HR = 1.27, 95% confidence interval [CI] = 1.23 to 1.31, P = 8.2 x 10(53)). In BRCA2 carriers, the strongest association with BC risk was seen for the overall BC PRS (HR = 1.22, 95% CI = 1.17 to 1.28, P = 7.2 x 10(-20)). The OC PRS was strongly associated with OC risk for both BRCA1 and BRCA2 carriers. These translate to differences in absolute risks (more than 10% in each case) between the top and bottom deciles of the PRS distribution; for example, the OC risk was 6% by age 80 years for BRCA2 carriers at the 10th percentile of the OC PRS compared with 19% risk for those at the 90th percentile of PRS. Conclusions: BC and OC PRS are predictive of cancer risk in BRCA1 and BRCA2 carriers. Incorporation of the PRS into risk prediction models has promise to better inform decisions on cancer risk management

Accessory gland as a site for prothoracicotropic hormone controlled ecdysone synthesis in adult male insects

Insect steroid hormones (ecdysteroids) are important for female reproduction in many insect species and are required for the initiation and coordination of vital developmental processes. Ecdysteroids are also important for adult male physiology and behavior, but their exact function and site of synthesis remains unclear, although previous studies suggest that the reproductive system may be their source. We have examined expression profiles of the ecdysteroidogenic Halloween genes, during development and in adults of the flour beetle Tribolium castaneum. Genes required for the biosynthesis of ecdysone (E), the precursor of the molting hormone 20-hydroxyecdysone (20E), are expressed in the tubular accessory glands (TAGs) of adult males. In contrast, expression of the gene encoding the enzyme mediating 20E synthesis was detected in the ovaries of females. Further, Spookiest (Spot), an enzyme presumably required for endowing tissues with competence to produce ecdysteroids, is male specific and predominantly expressed in the TAGs. We also show that prothoracicotropic hormone (PTTH), a regulator of E synthesis during larval development, regulates ecdysteroid levels in the adult stage in Drosophila melanogaster and the gene for its receptor Torso seems to be expressed specifically in the accessory glands of males. The composite results suggest strongly that the accessory glands of adult male insects are the main source of E, but not 20E. The finding of a possible male-specific source of E raises the possibility that E and 20E have sex-specific roles analogous to the vertebrate sex steroids, where males produce primarily testosterone, the precursor of estradiol. Furthermore this study provides the first evidence that PTTH regulates ecdysteroid synthesis in the adult stage and could explain the original finding that some adult insects are a rich source of PTTH

An original phylogenetic approach identified mitochondrial haplogroup T1a1 as inversely associated with breast cancer risk in BRCA2 mutation carriers

Introduction: Individuals carrying pathogenic mutations in the BRCA1 and BRCA2 genes have a high lifetime risk of breast cancer. BRCA1 and BRCA2 are involved in DNA double-strand break repair, DNA alterations that can be caused by exposure to reactive oxygen species, a main source of which are mitochondria. Mitochondrial genome variations affect electron transport chain efficiency and reactive oxygen species production. Individuals with different mitochondrial haplogroups differ in their metabolism and sensitivity to oxidative stress. Variability in mitochondrial genetic background can alter reactive oxygen species production, leading to cancer risk. In the present study, we tested the hypothesis that mitochondrial haplogroups modify breast cancer risk in BRCA1/2 mutation carriers. Methods: We genotyped 22,214 (11,421 affected, 10,793 unaffected) mutation carriers belonging to the Consortium of Investigators of Modifiers of BRCA1/2 for 129 mitochondrial polymorphisms using the iCOGS array. Haplogroup inference and association detection were performed using a phylogenetic approach. ALTree was applied to explore the reference mitochondrial evolutionary tree and detect subclades enriched in affected or unaffected individuals. Results: We discovered that subclade T1a1 was depleted in affected BRCA2 mutation carriers compared with the rest of clade T (hazard ratio (HR) = 0.55; 95% confidence interval (CI), 0.34 to 0.88; P = 0.01). Compared with the most frequent haplogroup in the general population (that is, H and T clades), the T1a1 haplogroup has a HR of 0.62 (95% CI, 0.40 to 0.95; P = 0.03). We also identified three potential susceptibility loci, including G13708A/rs28359178, which has demonstrated an inverse association with familial breast cancer risk. Conclusions: This study illustrates how original approaches such as the phylogeny-based method we used can empower classical molecular epidemiological studies aimed at identifying association or risk modification effects.Peer reviewe

Trajets épistolaires

Les contributions explorent le statut mobile des correspondances (des feuillets épars à l'objet éditorial, de la sphère privée à la sphère publique et médiatique, du document brut à l'élaboration littéraire) ; elles questionnent la porosité des frontières entre lettres et fiction ainsi que la fécondité des interférences entre l'épistolaire et le romanesque. Elles frayent aussi des chemins dans des corpus épistolaires inédits

Trajets épistolaires. Hommage à Brigitte Diaz

Titre de forme : Mélanges. Brigitte DiazInternational audienceLa lettre, voyageuse par nature, chemine sur les routes d'un lieu à l'autre, de l'expéditeur au destinataire ; chronique à deux plumes, ouverte à l'inconnu des jours à venir, la correspondance relie les êtres, raccorde les espaces, connecte les temps. Ce volume rend hommage à la chercheuse, Brigitte Diaz, qui a théorisé le nomadisme épistolaire et activement œuvré à la réhabilitation littéraire des correspondances. Traçant librement leurs itinéraires parmi des correspondances variées, les contributions explorent le statut mobile des correspondances (des feuillets épars à l'objet éditorial, de la sphère privée à la sphère publique et médiatique, du document brut à l'élaboration littéraire) ; elles questionnent la porosité des frontières entre lettres et fiction ainsi que la fécondité des interférences entre l'épistolaire et le romanesque. Elles frayent aussi des chemins dans des corpus épistolaires inédits ou très méconnus, ouvrant la voie à de nouveaux voyages et recherches

Interlude art public. Les métaphores inspirées de Philippe Decouflé

Nouvel Kevin, Ruby Christian, Simonet Julie. Interlude art public. Les métaphores inspirées de Philippe Decouflé. In: Raison présente, n°107, 3e trimestre 1993. Y-a-t-il un art contemporain ? pp. 105-107

Cahier Régional Occitanie sur les Changements Climatiques

Ce cahier régional complète l’état des lieux scientifique sur les changements climatiques du sud de la France, de l’Atlantique à la frontière italienne. C’est donc avec un décloisonnement régional qu’il doit se parcourir puisque complémentaire aux deux rapports régionaux de nos voisins, notamment pour les enjeux communs tels que ceux liés au littoral méditerranéen, aux Pyrénées ou à l’eau, compte tenu des bassins versants partagés

Cahier Régional Occitanie sur les Changements Climatiques

Ce cahier régional complète l’état des lieux scientifique sur les changements climatiques du sud de la France, de l’Atlantique à la frontière italienne. C’est donc avec un décloisonnement régional qu’il doit se parcourir puisque complémentaire aux deux rapports régionaux de nos voisins, notamment pour les enjeux communs tels que ceux liés au littoral méditerranéen, aux Pyrénées ou à l’eau, compte tenu des bassins versants partagés

Curbing deforestation among smallholders in the Amazon rainforest: impact evaluation of a REDD+ pilot project in the Transamazon highway

National audienceUsing original data collected from 181 small farmers in the State of Para in Brazil in 2010 and 2014, we show that REDD+ pilots using positive economic and agricultural incentives can slow down deforestation rates in areas dominated by smallholder properties, where command-and- control policies arise political and equity concerns. In the present paper we analyze, using an econometric approach based on DID-matching, the forest conservation impacts of a REDD+ pilot program in the Transamazon highway that combines Payments for Environmental Services (PES) with environmental sensitization and agricultural technical assistance. Although the program attracted farmers who do not depend on livestock and often have a higher wage income than non-participants, a potential limitation to maximizing the environmental additionality of the project, we find a significant conservation impact of the project. Yet at its early implementation stage, our results show that program participants devoted on average 66% of their land to forest in 2014 while it would have decreased to an estimated 61% without the project. We find that the forest conservation impact is even higher for the subset of farmerswho had previously participated in a similar program, suggesting a process of time-cumulative learning and confidence on external support that acts as a facilitator for reaching positive conservation outcomes. Moreover, our results show that the forest area has been preserved at the expense of pastures, not of croplands. Extending the average estimate to all participants, we conclude that the project avoided the emission of around 830 000 tCO2