Broken replication forks trigger heritable DNA breaks in the terminus of a circular chromosome

<p><u>(A) Circular map of the <i>E</i>. <i>coli</i> chromosome</u>: <i>oriC</i>, <i>dif</i> and <i>terD</i> to <i>terB</i> sites are indicated. Numbers refer to the chromosome coordinates (in kb) of MG1655. (<u>B) Linear map of the terminus region:</u> chromosome coordinates are shown increasing from left to right, as in the marker frequency panels (see Figure 1C for example), therefore in the opposite direction to the circular map. In addition to <i>dif</i> and <i>ter</i> sites, the positions of the <i>parS</i>_pMT1 sites used for microscopy experiments are indicated. (<u>C) MFA analysis of terminus DNA loss in the <i>recB</i> mutant</u>: sequence read frequencies of exponential phase cells normalized to the total number of reads were calculated for each strain. Ratios of normalized reads in isogenic wild-type and <i>recB</i> mutant are plotted against chromosomal coordinates (in kb). The profile ratio of the terminus region is enlarged and the profile of the corresponding entire chromosomes is shown in inset. Original normalized profiles used to calculate ratios are shown in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1007256#pgen.1007256.s005" target="_blank">S1 Fig</a>. The position of <i>dif</i> is indicated by a red arrow. The <i>ter</i> sites that arrest clockwise forks (<i>terC</i>, <i>terB</i>, green arrow) and counter-clockwise forks (<i>terA</i>, <i>terD</i>, blue arrow) are shown. <u>(D) Schematic representation of focus loss in the <i>recB</i> mutant:</u> Time-lapse microscopy experiments showed that loss of a focus in the <i>recB</i> mutant occurs concomitantly with cell division in one of two daughter cells, and that the cell that keeps the focus then generates a focus-less cell at each generation. The percentage of initial events was calculated as the percentage of cell divisions that generate a focus-less cell, not counting the following generations. In this schematic representation, two initial events occurred (generations #2 and #7) out of 9 generations, and focus loss at generation #2 is heritable. Panels shown in this figure were previously published in [<a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1007256#pgen.1007256.ref019" target="_blank">19</a>] and are reproduced here to introduce the phenomenon.</p

Study of predictive genetic factors of postoperative natural history of Crohn's disease

La maladie de Crohn est présente principalement dans les pays industrialisés. En France, elle touche 1 personne sur 1000. L’incidence est de 5 pour 100000 habitants par an. A l’heure actuelle sa pathogénie reste mal expliquée et de nombreux facteurs interviennent (facteurs génétiques, immunologiques et environnementaux). Il semble donc essentiel de mieux comprendre la pathogénie de la maladie de Crohn afin d’identifier des cibles thérapeutiques permettant d’améliorer sa prise en charge et d’identifier des facteurs prédictifs de la récidive post-opératoire et des complications post-opératoires afin de personnaliser la prise en charge de chaque patient. Dans ce travail nous avons montré qu'un variant génétique de CARD8 (rs2043211) est un facteur de risque de récidive post-opératoire. Cette association n’est pas influencée par les autres facteurs de risque connus comme le tabagisme actif. L’identification de CARD8 comme un facteur de risque génétique de risque de récidive chirurgicale est d’un intérêt particulier puisqu’il pourrait devenir une nouvelle cible thérapeutique pour le traitement de la maladie de Crohn dans la période post-opératoire. Notre travail a également montré qu'un variant génétique de NOD2 (rs5743289) est un facteur de risque de complications intra-abdominales infectieuses post-opératoires (CIIP) après chirurgie dans la maladie de Crohn. L’identification de NOD2 comme un gène à risque pour la survenue de CIIP pourrait permettre d’établir une stratification précoce des patients à haut risque de CIIP chez qui la chirurgie devra être planifiée et prédire les patients à haut risque de CIIP. Des études sur larges effectifs avec cohorte de réplication restent encore nécessaires avant que les patients puissent bénéficier des retombées de ces outils en pratique couranteCrohn's disease occurs mainly in industrialized countries. In France it affects 1 person in 1000. The incidence is 5 per 100,000 persons per year. At present its pathogenesis remains poorly explained and many factors are involved (genetic, immunological and environmental). It seems essential to better understand Crohn's disease pathogenesis in order to identify therapeutic targets to improve its management and to identify predictors of postoperative recurrence and postoperative complications to customize the care of each patient. In this work we showed that a genetic variant of CARD8 (rs2043211) is a risk factor for postoperative recurrence. This combination is not influenced by the other known risk factors such as active smoking. Identifying CARD8 as a genetic risk factor for risk of surgical recurrence is of particular interest since it may become a novel therapeutic target for the treatment of Crohn's disease in the post-operative period. Our work has also shown that a genetic variant of NOD2 (rs5743289) is a risk factor for postoperative intraabdominal infectious complications (CIIP) after surgery in Crohn's disease. The identification of NOD2 gene as a risk factor for the occurrence of CIIP could establish an early stratification of patients at high risk for CIIP in whom surgery should be planned and predict patients at high risk for CIIP. Studies with large numbers replication cohort are still necessary before patients can enjoy the benefits of these tools in clinical practic

Étude des facteurs génétiques prédictifs de l’histoire naturelle postopératoire de la maladie de Crohn

Crohn's disease occurs mainly in industrialized countries. In France it affects 1 person in 1000. The incidence is 5 per 100,000 persons per year. At present its pathogenesis remains poorly explained and many factors are involved (genetic, immunological and environmental). It seems essential to better understand Crohn's disease pathogenesis in order to identify therapeutic targets to improve its management and to identify predictors of postoperative recurrence and postoperative complications to customize the care of each patient. In this work we showed that a genetic variant of CARD8 (rs2043211) is a risk factor for postoperative recurrence. This combination is not influenced by the other known risk factors such as active smoking. Identifying CARD8 as a genetic risk factor for risk of surgical recurrence is of particular interest since it may become a novel therapeutic target for the treatment of Crohn's disease in the post-operative period. Our work has also shown that a genetic variant of NOD2 (rs5743289) is a risk factor for postoperative intraabdominal infectious complications (CIIP) after surgery in Crohn's disease. The identification of NOD2 gene as a risk factor for the occurrence of CIIP could establish an early stratification of patients at high risk for CIIP in whom surgery should be planned and predict patients at high risk for CIIP. Studies with large numbers replication cohort are still necessary before patients can enjoy the benefits of these tools in clinical practiceLa maladie de Crohn est présente principalement dans les pays industrialisés. En France, elle touche 1 personne sur 1000. L’incidence est de 5 pour 100000 habitants par an. A l’heure actuelle sa pathogénie reste mal expliquée et de nombreux facteurs interviennent (facteurs génétiques, immunologiques et environnementaux). Il semble donc essentiel de mieux comprendre la pathogénie de la maladie de Crohn afin d’identifier des cibles thérapeutiques permettant d’améliorer sa prise en charge et d’identifier des facteurs prédictifs de la récidive post-opératoire et des complications post-opératoires afin de personnaliser la prise en charge de chaque patient. Dans ce travail nous avons montré qu'un variant génétique de CARD8 (rs2043211) est un facteur de risque de récidive post-opératoire. Cette association n’est pas influencée par les autres facteurs de risque connus comme le tabagisme actif. L’identification de CARD8 comme un facteur de risque génétique de risque de récidive chirurgicale est d’un intérêt particulier puisqu’il pourrait devenir une nouvelle cible thérapeutique pour le traitement de la maladie de Crohn dans la période post-opératoire. Notre travail a également montré qu'un variant génétique de NOD2 (rs5743289) est un facteur de risque de complications intra-abdominales infectieuses post-opératoires (CIIP) après chirurgie dans la maladie de Crohn. L’identification de NOD2 comme un gène à risque pour la survenue de CIIP pourrait permettre d’établir une stratification précoce des patients à haut risque de CIIP chez qui la chirurgie devra être planifiée et prédire les patients à haut risque de CIIP. Des études sur larges effectifs avec cohorte de réplication restent encore nécessaires avant que les patients puissent bénéficier des retombées de ces outils en pratique courant

Mate-choice copying in Drosophila melanogaster: Impact of demonstration conditions and male–male competition

International audienceIndividuals of many species, including invertebrates, have been shown to use social information in mate choice, notably by extracting information from the mating performance of opposite sex conspecifics, a process called “mate-choice copying” (MCC). Here, we performed four experiments with Drosophila melanogaster to investigate two aspects of MCC methodology: whether providing positive and negative social information simultaneously or sequentially during the demonstration phase of the protocol, and male–male competition during the mate-choice test, affect MCC. We found that the simultaneous provision of positive and negative information during demonstrations hampered female MCC performance, compared to the sequential provision of information. This can be interpreted in two alternative, yet not exclusive, ways: attentional mechanisms may restrict the focus of the brain to one source of information at a time, and/or the shorter duration of demonstrations in the simultaneous protocol may have not permit full social learning use and may explain the non-detection of MCC in that protocol. Moreover, we did not detect any significant effect of male–male competition on female choice. This study thus provides further evidence for MCC in D. melanogaster and expands on the necessary methodology for detailed studies

Is Hartmann’s Pouch an Option in the Management of Acute Severe Ulcerative Colitis?

Background: The surgical management of remnant rectosigmoid after subtotal colectomy with end ileostomy for acute severe ulcerative colitis remains controversial with respect to the need to perform sigmoidostomy or Hartmann’s pouch. The aim of this retrospective study was to investigate whether Hartmann’s pouch may be a safe option. Methods: Thirty-eight Hartmann’s pouches were performed between January 2003 and December 2015. We looked at morbidity (with a focus on the occurrence of pelvic sepsis and leakage of the rectal stump) and the rate of restored intestinal continuity. Results: Nineteen patients had surgical complications. Seven had an intra-abdominal collection, only one of which was in the pelvis, and the patient had to be reoperated. Only one patient had a reopening of the rectal stump, which was revealed by rectal bleeding. Twenty-six patients (68.4%) underwent further proctectomy with ileal J-pouch anal anastomosis with no difficulty in localizing or mobilizing the rectal stump and no major surgical complications. Conclusions: Hartmann’s pouch may be considered in patients with acute severe ulcerative colitis, with low rates of morbidity and pelvic sepsis. The restoration of intestinal continuity is possible after this procedure without any special difficulty

Simulator Practice Is Not Enough to Become a Robotic Surgeon: The Driving Lessons Model

International audienc

Long-term Outcomes of Robot-assisted Laparoscopic Rectopexy for Rectal Prolapse

International audienceBACKGROUND: Robot-assisted laparoscopic rectopexy for total rectal prolapse is safe and feasible. Small series proved clinical and functional short-term results comparable with conventional laparoscopy. No long-term results have been reported yet.OBJECTIVE: The primary objective of the study was to evaluate long-term functional and anatomic results of robot-assisted laparoscopic rectopexy. The secondary objective was to evaluate the learning curve of this procedure.DESIGN: Monocentric study data, both preoperative and perioperative, were collected prospectively, and follow-up data were assessed by a telephone questionnaire.SETTINGS: The study was performed in an academic center by 3 different surgeons.PATIENTS: We evaluated all of the consecutive patients who underwent a robot-assisted laparoscopic rectopexy between June 2002 and August 2010.INTERVENTION: Rectopexy was performed with 2 anterolateral meshes or with 1 ventral mesh, and in 9 patients a sigmoidectomy was associated with rectopexy.MAIN OUTCOME MEASURES: The actuarial recurrence rate was evaluated using the Kaplan-Meier method.RESULTS: During the study period, 77 patients underwent a robot-assisted laparoscopic rectopexy, and the mean age was 59.9 years (range, 23–90 y). Average operating time was 223 minutes (range, 100–390 min); the learning curve was completed after 18 patients were seen. Two patients died of causes unrelated to surgery at 5 and 24 months. There were 5 conversions (6%) to open procedure. Overall morbidity was low and concerned only 8 patients (10.4%). Mean follow-up time was 52.5 months (range, 12–115 mo). Recurrences have been observed in 9 patients (12.8%). Preoperatively, 24 (34%) of the patients had constipation. Postoperatively, constipation disappeared for 12 (50%) of 24 and constipation appeared for 11 (24%) of 46 patients. Fecal incontinence decreased after surgery from Wexner score 10.5 to 5.1 of 20.LIMITATIONS: There was a lack of standardization of the surgical procedure. The study was monocentric. Seven patients (9%) were lost to follow-up.CONCLUSIONS: Long-term results of robot-assisted laparoscopic rectopexy are satisfying. Further studies comparing robot-assisted and conventional laparoscopy, including cost-effectiveness, are needed

Whole-Exome Sequencing of Bronchial Epithelial Cells Reveals a Genetic Print of Airway Remodelling in COPD

International audienceThe remodelling of the airways is a hallmark of chronic obstructive pulmonary disease, but it is highly heterogeneous and erratically distributed in the airways. To assess the genetic print of remodelling in chronic obstructive pulmonary disease (COPD), we performed a comparative whole-exome sequencing analysis on microdissected bronchial epithelia. Lung resections from four non-COPD and three COPD subjects (ex-smokers and current smokers) were formalin-fixed paraffin-embedded (FFPE). Non-remodelled and remodelled bronchial epithelia were isolated by laser microdissection. Genomic DNA was captured and sequenced. The comparative quantitative analysis identified a list of 109 genes as having variants in remodelled epithelia and 160 genes as having copy number alterations in remodelled epithelia, mainly in COPD patients. The functional analysis highlighted cilia-associated processes. Therefore, bronchial-remodelled epithelia appeared genetically more altered than non-remodelled epithelia. Characterizing the unique molecular print of airway remodelling in respiratory diseases may help uncover additional factors contributing to epithelial dysfunctions, ultimately providing additional targetable proteins to correct epithelial remodelling and improve lung function

Impacts of land use change on biomass and diversity in the forest landscape of the Yangambi Biosphere Reserve in the Democratic Republic of Congo

peer reviewedThe tropical forests of the Democratic Republic of Congo are threatened by deforestation and forest degradation, which affect tree structure and diversity. This study aims to quantify biomass and diversity losses resulting from deforestation and degradation, with a focus on the Yangambi Biosphere Reserve. Invento-ries were conducted in four 50 m x 50 m plots in each of the eight land-use types identified: mixed mature forest, mature forest with Gilbertiodendron dewevrei, subsistence crop fields, fallows (5 to 10 years), secondary forests (20 to 40 years), and cacao, coffee and oil palm plantations. Biomass stocks in mature forests amounted to ~ 400 and 380 Mg/ha for G. dewevrei and mixed forest respec-tively. Our results show that mature forests lose 50, 70 and 90%, respectively, of their above-ground biomass when converted to cocoa, coffee and palm plantations, and almost all (99%) when converted to food crops. However, when a crop field is abandoned, above-ground biomass gradually recovers to 7.5% after 5-10 years and to 38.8% after 20-40 years. Conversion also has an impact on diversity, and although species rich-ness appears to recover faster than bio-mass, its composition is fundamentally altered. Although the approach needs to be scaled up, these results provide essential information for quantifying the impacts of “natural” solutions to climate change, i.e. protection of mature forests, improved forest management and refor-estation.Les forêts tropicales de la République démocratique du Congo sont menacées par la déforestation et la dégradation forestière, qui affectent la structure et la diversité arborée. Cette étude a pour objectif de quantifier les pertes de biomasse et de diversité liées à la déforestation et à la dégradation, en se concentrant sur la réserve de biosphère de Yangambi. Quatre parcelles de 50 m x 50 m ont été inventoriées dans chacun des huit types d’utilisation des terres identifiés : la forêt mature mixte, la forêt mature à Gilbertiodendron dewevrei, les champs des cultures vivrières, les jachères (5 à 10 ans), les forêts secondaires (20 à 40 ans), les plantations de cacaoyers, les plantations de caféiers et les plantations de palmiers à huile. Les stocks de biomasse dans les forêts matures s’élèvent à environ 400 et 380 Mg/ha respectivement pour la forêt à G. dewevrei et la forêt mixte. Les résultats montrent que la forêt mature perd 50, 70 et 90 % de sa biomasse aérienne quand elle est convertie en plantations de cacaoyers, caféiers et palmiers, respectivement, et la quasi-totalité (99 %) lorsqu’elle est convertie en champs de cultures vivrières ; mais quand le champ est abandonné, la biomasse se reconstitue progressivement à 7,5 % après 5 à 10 ans et à 38,8 % après 20 à 40 ans. La diversité est aussi impactée par la conversion, et, bien que la richesse spécifique semble se reconstituer plus rapidement que la biomasse, la composition est fondamentalement modifiée. Ces résultats fournissent des informations essentielles pour quantifier les impacts des solutions « naturelles » pour lutter contre le changement climatique : la protection des forêts matures, l’amélioration de la gestion forestière et le reboisement ; même si l’approche doit être étendue à plus grande échelle.Los bosques tropicales de la República Democrática del Congo están amenazados por la deforestación y la degradación forestal, que afectan a la estructura y la diversidad de los árboles. Este estudio preten e cuantificar la pérdida de biomasa y de diversidad debida a la defo estación y a la degradación, centrándose en la Reserva de la Biosfera de Yangambi. Se han estudiado cuatro parcelas de 50 m x 50 m en cada uno de los ocho tipos de uso de la tierra identificados: bosque maduro mixto, bosque maduro de Gilbertiodendron dewevrei, campos de cultivo alimentario, barbecho (5 a 10 años), bosque secundario (20 a 40 años), plantaciones de árboles del cacao, plantaciones de cafetos y plantaciones de palma aceitera. Las existencias de biomasa en los bosques maduros ascienden a ~400 y 380 Mg/ha para el bosque de G. dewevrei y el bosque mixto, respectivamente. Los resultados muestran que el bosque maduro pierde el 50, el 70 y el 90 % de su biomasa aérea cuando se convierte en plantaciones de cacao, café y palma, respectivamente, y casi toda (99 %) cuando se convierte en campos de cultivos alimentarios; pero cuando se abandona el campo, la biomasa se recupera gradualmente hasta el 7,5 % después de 5-10 años y hasta el 38,8 % después de 20-40 años. La diversidad también se ve afectada por la conversión, y aunque la riqueza de especies parece recuperarse más rápidamente que la biomasa, la composición se altera fundamentalmente. Estos resultados proporcionan información esencial para cuantificar los impactos de las soluciones “naturales” en la lucha contra el cambio climático: protección de los bosques maduros, mejora de la gestión forestal y reforestación; aunque el enfoque debe ampliarse a una escala superior