Germline mutation in the RAD51B gene confers predisposition to breast cancer.

International audienceBACKGROUND: Most currently known breast cancer predisposition genes play a role in DNA repair by homologous recombination. Recent studies conducted on RAD51 paralogs, involved in the same DNA repair pathway, have identified rare germline mutations conferring breast and/or ovarian cancer predisposition in the RAD51C, RAD51D and XRCC2 genes. The present study analysed the five RAD51 paralogs (RAD51B, RAD51C, RAD51D, XRCC2, XRCC3) to estimate their contribution to breast and ovarian cancer predisposition. METHODS: The study was conducted on 142 unrelated patients with breast and/or ovarian cancer either with early onset or with a breast/ovarian cancer family history. Patients were referred to a French family cancer clinic and had been previously tested negative for a BRCA1/2 mutation. Coding sequences of the five genes were analysed by EMMA (Enhanced Mismatch Mutation Analysis). Detected variants were characterized by Sanger sequencing analysis. RESULTS: Three splicing mutations and two likely deleterious missense variants were identified: RAD51B c.452 + 3A > G, RAD51C c.706-2A > G, RAD51C c.1026 + 5_1026 + 7del, RAD51B c.475C > T/p.Arg159Cys and XRCC3 c.448C > T/p.Arg150Cys. No RAD51D and XRCC2 gene mutations were detected. These mutations and variants were detected in families with both breast and ovarian cancers, except for the RAD51B c.475C > T/p.Arg159Cys variant that occurred in a family with 3 breast cancer cases. CONCLUSIONS: This study identified the first RAD51B mutation in a breast and ovarian cancer family and is the first report of XRCC3 mutation analysis in breast and ovarian cancer. It confirms that RAD51 paralog mutations confer breast and ovarian cancer predisposition and are rare events. In view of the low frequency of RAD51 paralog mutations, international collaboration of family cancer clinics will be required to more accurately estimate their penetrance and establish clinical guidelines in carrier individuals

Quand les ergonomes sont sortis du laboratoire.... à propos du travail des femmes dans l’industrie électronique (1963 – 1973)

Cette réflexion collective sur la première recherche « de terrain » (il y a 40 ans !) des ergonomes du Conservatoire National des Arts et Métiers (Paris), associe des syndicalistes (« demandeurs ») et des ergonomes (« réalisateurs »). Elle vise à reconstituer le déroulement de cette expérience commune et à tirer des enseignements concernant action syndicale, production des connaissances ergonomiques et transformation du travail. Par le mode d’entrée des chercheurs dans l’entreprise, l’élaboration progressive de la démarche, la production de connaissances inattendues sur le travail réel et ses effets sur la santé, cette recherche sur le travail des femmes ouvrières de la production de masse marque un tournant épistémologique en ergonomie. Obligeant à inventer de nouvelles méthodes, de nouvelles postures de recherche en reconnaissant « l’expertise ouvrière », de nouveaux modèles de l’activité de travail, elle jette les bases d’une dynamique « tourbillonnaire » prolongée jusqu’aujourd’hui fondée sur la coopération entre acteurs et articulant recherche, formation et action. Développements et limites sont aussi soulignés.This collective reflection on the first field study (40 years ago!) conducted by ergonomists from Conservatoire National des Arts et Métiers (Paris) is produced jointly by union representatives who requested the research and by ergonomists who conducted it. The aim is to piece together the flow of events in this common experience and to draw lessons about union action, the production of ergonomic knowledge, and work transformation. This research project on the work of female mass production workers marked an epistemological turning point in ergonomics, due to a number of factors: how the researchers entered the workplace, the progressive development of the research process, and the production of unexpected knowledge on the « real » work and its effects on health. New methods, a new research position recognizing « workers’ expertise », and new models of the work activity had to be developed. The study then established the foundation for an ongoing dynamics based on cooperation between the different actors, and linking research, training and action. Developments and limitations are also discussed.Esta reflexión colectiva sobre la primera investigación « de terreno » (hace 40 años !) de los ergónomos del Conservatoire National des Arts et Métiers (Paris), asocia a los sindicalistas (« solicitantes ») y a los ergónomos (« realizadores »). La reflexión pretende reconstituir el desarrollo de esta experiencia común y obtener lecciones sobre la acción sindical, la producción de los conocimientos ergonómicos y la transformación del trabajo. Esta investigación sobre el trabajo de las obreras de la producción en masa marca un hito epistemológico en ergonomía por el modo de entrada de los investigadores en la empresa, la elaboración progresiva del proceso de investigación y la producción de conocimientos inesperados sobre el trabajo real y sus efectos sobre la salud. Obligando a inventar nuevos métodos, nuevas posturas en la investigación que reconocen el « conocimiento obrero », nuevos modelos de la actividad de trabajo, esta reflexión sienta las bases de una dinámica « en torbellino » que se prolonga hasta hoy fundada en la cooperación entre actores y articulando investigación, formación y acción. Se discuten también las perspectivas y los límites

Importance of pre-analytical steps for transcriptome and RT-qPCR analyses in the context of the phase II randomised multicentre trial REMAGUS02 of neoadjuvant chemotherapy in breast cancer patients

<p>Abstract</p> <p>Background</p> <p>Identification of predictive markers of response to treatment is a major objective in breast cancer. A major problem in clinical sampling is the variability of RNA templates, requiring accurate management of tumour material and subsequent analyses for future translation in clinical practice. Our aim was to establish the feasibility and reliability of high throughput RNA analysis in a prospective trial.</p> <p>Methods</p> <p>This study was conducted on RNA from initial biopsies, in a prospective trial of neoadjuvant chemotherapy in 327 patients with inoperable breast cancer. Four independent centres included patients and samples. Human U133 GeneChips plus 2.0 arrays for transcriptome analysis and quantitative RT-qPCR of 45 target genes and 6 reference genes were analysed on total RNA.</p> <p>Results</p> <p>Thirty seven samples were excluded because <it>i) </it>they contained less than 30% malignant cells, or <it>ii) </it>they provided RNA Integrity Number (RIN) of poor quality. Among the 290 remaining cases, taking into account strict quality control criteria initially defined to ensure good quality of sampling, 78% and 82% samples were eligible for transcriptome and RT-qPCR analyses, respectively. For RT-qPCR, efficiency was corrected by using standard curves for each gene and each plate. It was greater than 90% for all genes. Clustering analysis highlighted relevant breast cancer phenotypes for both techniques (ER+, PR+, HER2+, triple negative). Interestingly, clustering on trancriptome data also demonstrated a "centre effect", probably due to the sampling or extraction methods used in on of the centres. Conversely, the calibration of RT-qPCR analysis led to the centre effect withdrawing, allowing multicentre analysis of gene transcripts with high accuracy.</p> <p>Conclusions</p> <p>Our data showed that strict quality criteria for RNA integrity assessment and well calibrated and standardized RT-qPCR allows multicentre analysis of genes transcripts with high accuracy in the clinical context. More stringent criteria are needed for transcriptome analysis for clinical applications.</p

Variations in bulk leaf carbon isotope discrimination, growth and related leaf traits among three Populus nigra L. populations

The ongoing global change could be an additional threat to the establishment and the long-term survival of Populus nigra L., an emblematic European riparian species. With the general aim of gaining insights into the adaptive potential of this species, we (i) quantified variations within and among three French P. nigra populations for key physiological attributes, i.e., water-use efficiency (assessed from bulk leaf carbon isotope discrimination, Δ13C), growth performance and related leaf traits, (ii) examined genotype and population by environment interactions, and (iii) explored the relationship between Δ13C and growth. Thirty genotypes were sampled in each of three naturally established populations and grown in two different sites, Orléans (ORL) and Guémené-Penfao (GMN). In ORL, two similar plots were established and different watering regimes were applied in order to test for the drought response. Significant variations were observed for all traits within and among populations irrespective of site and watering. Trait variation was larger within than among populations. The effect of drought was neither genotype- nor population-dependent, contrary to the effect of site. The population ranking was maintained in all sites and watering regimes for the two most complex traits: Δ13C and growth. Moreover, these two traits were unrelated, which indicates that (i) water-use efficiency and growth are largely uncoupled in this species, and (ii) the environmental factors driving genetic structuration for Δ13C and growth act independently. The large variations found within populations combined with the consistent differences among populations suggest a large adaptive potential for P. nigra

Is the ranking of poplar genotypes for leaf carbon isotope discrimination stable across sites and years in two different full-sib families?

- Introduction Because of its vigorous growth, poplar can play an important role for sustainable production of woody biomass to cover renewable energy needs. Hence, the selection of suitable genotypes has to be based on relevant traits, among which intrinsic water use efficiency (Wi, estimated through leaf carbon isotope discrimination, Δ) may be a key trait. Besides a large genetic variation in Δ among the frequently planted poplar hybrids, the use of Δ in deployment or breeding programmes requires insights in the robustness of the genotype ranking for Δ across environments and years. - Methods Two F1 full-sib families of poplar (Populus deltoides × Populus nigra and Populus deltoides × Populus trichocarpa) were grown at two sites in Europe, i.e. northern Italy and central France. For each family, leaf samples from 31 F1 genotypes collected during different field studies were used (1) to assess the effect of genotype, site and year on Δ in leaves, as well as their mutual interactions, and (2) to elucidate the relationships between Δ, leaf morphology and tree dimensions. - Results Under the well-watered conditions of our study, a low to moderate genetic variability was observed in the two poplar families. Within-family broad-sense heritability values ranged from 0 to 0.49. The ranking of genotypes for Δ was more stable between years than between sites. - Conclusions The study confirmed the occurrence of some degree of genetic variability ofΔ in the studied poplar families and the possibility to identify genotypes with low, stable Δ values across years. However, the significant genotype-by-site interactions in our study suggest that selection for larger water use efficiency or lower Δ in these families has to consider specific responses in different environments

Populus nigra as keystone species able to cope with the ongoing climate change

International audiencePopulus nigra L. is one important species of the european alluvial forests, that are protected under Habitats directive 92/43/EEC in Europe. This species is often regarded as good indicator of geomorphological and biological quality of this ecosytem and is an active support of riparian biodiversity. This species is threatened by anthropogenic disturbances and gene introgression, justifying a french and european (EUFORGEN) programme on in situ and ex situ conservation of its genetic resources. In addition, riparian forest ecosystem and trees will face global and local climate modifications this century. Populus nigra, that establishes naturally within or along the active channel and that is strictly dependent of the morphodynamics of the river, will be exposed to three new threats : (i) enhancement of the frequency and severity of drought with summer decrease of the water table level, (ii) extreme heat waves, especially in summer (temperature is a key factor for survival and development of seedlings) and (iii) more intense flooding. The basis for the ability of trees to survive, adapt and evolve under changing environmental conditions is genetic diversity and the adaptive capacity to such changes involve three processes : (a) plasticity, i.e. the capacity of existing trees to respond differently to different environmental conditions ; (b) adaptation, which includes adaptive genetic diversity and the occurrence of natural selection in a dynamic system and (c) migration potential through natural dissemination of seeds to more suitable areas. This presentation will focuss on the two first responses in Populus nigra, as the third process is restricted, due to the limited capacity of this pionneer species to migrate in latitude or elevation along the constrained range of the fluvial corridors. Data on genetic diversity and phenotypic variability of adaptative traits in french populations (foliar characteristics, water relations, architecture, floral and foliar phenology…) and from in situ and ex situ experiments, testing drought and temperature in different genetic material (cuttings, seedlings) in various conditions (sandy banks, nursery, greenhouses, growth chambers) will be presented. This communication will demonstrate that Populus nigra has resources (genetic characteristics) and mechanisms (ecophysiological characteristics) to cope with the ongoing climate change. This research was mainly supported by regional, national and european funds and realized under the french Populus nigra genetic resource conservation programme