Assessing the efficiency of an elver ladder using a multi-state mark-recapture model

International audienceThe decline of the European eel (Anguilla anguilla) stock has led the European Commission to enforce a regulation (Council Regulation N°1100/2007), in which each member state was required to establish an eel management plan. Various measures in the French plan aim at restoring river connectivity by mitigating the impact of obstacles on the colonization of continental water by eels. Consequently, many obstacles are going to be equipped with elver ladder in the near future. In this context, a method to assess the passability of an obstacle seems essential. In this study, we developed a tag–recapture method, appropriate to glass eels and elvers, and an associated multi-state mark–recapture model (i) to assess the passability of a ladder and (ii) to quantify the effect of various environmental factors on this passability. An application to a specific obstacle is applied as an illustrative example that demonstrates the relevance of the assessment method, and how the results can be used to propose technical solution to improve the efficiency of the ladder. Nine tag–recapture campaigns were carried on this obstacle, and about 4400 young eels were tagged. The model demonstrates that the efficiency of the ladder was rather low, especially during low river flow periods, mainly because of accessibility problems. The model also demonstrates the major influence of the river flow on the probability for an eel to pass the ladder; consequently, managing river flow during the migration period can be a relevant measure to improve river connectivity and facilitate colonization of the watershed

Evaluation de l'efficacité d'une passe à anguilles à partir de données de marquage-recapture et d'un modèle Bayésien

International audienceThe decline of the European eel (Anguilla anguilla) stock has led the European Commission to initiate an Eel Recovery Plan (Council Regulation N0 1100/2007), in which each member state was required to establish Eel Management Plans. Various measures in the French plan aim at minimizing the impact of obstacles on the colonisation of continental water by glass eels. In this context, a method to assess the passability of an obstacle seems essential. Tag-recaptures methods are often used for analysis. In this study, we developed a specific tag-recaptures method appropriate to elvers and an associated Bayesian model to assess (i) the passability of a ladder and (ii) to quantify the effect of various environmental factors on the passability. Nine tag-recaptures campaigns were carried out from 2009 to 2011 on an obstacle named “Pas-du-Bouc” (France) equipped with an eel ladder and trap since 2008. The site is located about 3 kilometers upstream from the tidal limit. About 4400 young eels (total length between 55 and 240mm) were tagged by batch (a batch corresponding to a campaign and a release location) using coloured Visible Implant Elastomers (VIE), enabling the identification of the batches. Fishes were released in 50 batches either 100m downstream, or directly down the ladder. The trap was then visited every two days and the batch of trapped eels were identified thank to the VIE. A Bayesian model was then developed to analyse the results. This model aims at predicting the probability for an elver of climbing the ladder according to some batch characteristics (release location), eels characteristics (length and sanitary conditions) and environmental conditions (especially temperature and river flow). The probability of climbing was subdivided into two steps: first the probability for an eel in the river to find and climb the ladder and (ii) the probability for an elver that have found the ladder to climb it. About 50% of eels released in front of the ladder were recaptured, while only 22% were recaptured when released downstream. Moreover, it is generic and has already been applied to two other obstacles. Concerning the Bayesian model, it was able to predict well the probability for an elver to climb the ladder, and it especially demonstrates the major influence of the river flow on the probability for an eel to reach the ladder. The model will be applied to other sites in order to distinguish environmental factors that are site specific or more general

Analyse du niveau de transparence d'un ouvrage hydraulique vis-à-vis des civelles et jeunes anguilles jaunes

National audienceL'effondrement du stock d'anguilles européennes a poussé à la mise en oeuvre d'un plan européen de restauration (Règlement CE / n° 1100/2007 du 18/09/2007). Parmi l'ensemble des mesures préconisées, figurent celles visant à diminuer l’impact des ouvrages hydrauliques sur la phase de colonisation des eaux continentales. Pour accompagner ce type de démarche, il apparaît important de disposer de méthodes permettant d’évaluer le niveau de transparence d’un ouvrage avant et après son aménagement ou la modification de sa gestion. Parmi les méthodes envisageables, l’usage du marquage d’individus avec remise en aval de l’ouvrage est assez fréquemment cité. Afin de préciser l’intérêt mais aussi les limites d’une telle démarche, des suivis précis ont été mis en oeuvre sur deux sites, l’un au nord du Bassin d’Arcachon, l’autre sur le barrage des Enfreneaux sur la Sèvre niortaise.Le premier, l’ouvrage du Pas du Bouc, équipé depuis 2008, est situé sur le canal du Porge reliant le lac de Lacanau au bassin d'Arcachon, à 3-4 kilomètres en amont de la zone de marée dynamique. On notera la présence d’une pêcherie professionnelle civellière au tamis à main sur la zone estuarienne de ce canal. En lien avec le suivi très régulier et précis des passages sur la rampe, réalisé par la Fédération de Pêche de Gironde pendant la saison de migration, un certain nombre d’analyses et d’essais ont été mis en oeuvre par le Pôle Ecohydraulique. L’analyse de la cinétique de migration lors de trois saisons successives a ainsi été effectuée et l’influence respective de différents facteurs environnementaux a été testée. L’influence majeure de la température de l’eau du Bassin et du Canal sur la phase d’ouverture de la fenêtre de migration et du débit du canal au sein de cette fenêtre ressortent ainsi nettement. Neuf campagnes ont permis le marquage par élastomère de couleur (VIE) de près de 4500 individus. Lors de chaque campagne, quatre lots étaient identifiés, l’un étant remis au pied même de la rampe, deux étaient remis à l’eau dans le canal (rive droite et rive gauche) en aval des turbulences liées au barrage et enfin un lot était suivi sur 96 h en cage de survie. Les individus testés étaient majoritairement des migrants ayant déjà franchi la passe, mais différents tests ont également été effectués sur des individus prélevés en aval de l’ouvrage (engin passif ou pêche électrique). L’analyse bayésienne des résultats est en cours, mais il ressort dès à présent une bonne cohérence entre les lots marqués et remis en rivière et le comportement des migrants non marqués, notamment en ce qui concerne l’influence très positive du débit sur les niveaux de passage et/ou de recapture. L’importance de la prédation naturelle (perches, perches-soleil, écrevisses de Louisiane) est également fortement soupçonnée. Cette stratégie d’évaluation, lourde à mettre en oeuvre, apparaît surtout bien adaptée aux très jeunes individus à fort comportement migratoire observés sur des sites en aval des bassins versants. Au-dessus de 15-20 cm, les faibles probabilités de recapture remettent en effet fortement en cause ce type d’approche

Combined Reverse-Transcriptase Multiplex Ligation-Dependent Probe Amplification and Next-Generation Sequencing Analyses to Assign Unclassified BCL2−/BCL6− Nonrearranged Small B-Cell Lymphoid Neoplasms as Follicular or Nodal Marginal Zone Lymphoma.

Distinguishing between follicular lymphoma (FL) and nodal marginal zone lymphoma (NMZL) can be difficult when morphologic and phenotypic features are unusual and characteristic cytogenetic rearrangements are absent. We evaluated the diagnostic contribution of ancillary techniques-including fluorescence in situ hybridization (FISH)-detected 1p36 deletion; reverse-transcriptase, multiplex, ligation-dependent probe amplification (RT-MLPA); and next-generation sequencing (NGS)-for tumors that remain unclassified according to standard criteria. After review, 50 CD5-negative small B-cell lymphoid neoplasms without BCL2 and BCL6 FISH rearrangements were diagnosed as FLs (n = 27), NMZLs (n = 5), or unclassified (n = 18) based on the 2016 World Health Organization Classification of Tumours of Haematopoietic and Lymphoid Tissues. FISH helped identify the 1p36 deletion in 3 FLs and 1 unclassified tumor. Most classified FLs had an RT-MLPA germinal center B-cell (GCB) signature (93%) or were noncontributive (7%). Classified NMZLs had an RT-MLPA activated B-cell signature (20%), had an unassigned signature (40%), or were noncontributive (40%). Among unclassified tumors, the RT-MLPA GCB signature was associated with mutations most commonly found in FLs (CREBBP, EZH2, STAT6, and/or TNFRSF14) (90%). An RT-MLPA-detected GCB signature and/or NGS-detected gene mutations were considered as FL identifiers for 13 tumors. An activated B-cell signature or NOTCH2 mutation supported NMZL diagnosis in 3 tumors. Combining the RT-MLPA and NGS findings successfully discriminated 89% of unclassified tumors in favor of one or the other diagnosis. NGS-detected mutations may be of therapeutic interest. Herein, we detected 3 EZH2 and 8 CREBBP mutations that might be eligible for targeted therapies

"Double-hit" chronic lymphocytic leukemia: An aggressive subgroup with 17p deletion and 8q24 gain

Chronic lymphocytic leukemia (CLL) with 17p deletion (17p-) is associated with a lack of response to standard treatment and thus the worst possible clinical outcome. Various chromosomal abnormalities (including unbalanced translocations, deletions, ring chromosomes and isochromosomes) result in the loss of 17p and one copy of the TP53 gene. The objective of the present study was to determine whether the type of chromosomal abnormality leading to 17p- and the additional aberrations influenced the prognosis in a series of 195 patients with 17p-CLL. Loss of 17p resulted primarily from an unbalanced translocation (70%) with several chromosome partners (the most frequent being chromosome 18q), followed by deletion 17p (23%), monosomy 17 (8%), isochromosome 17q [i(17q)] (5%) and a ring chromosome 17 (2%). In a univariate analysis, monosomy 17, a highly complex karyotype (≥5 abnormalities), and 8q24 gain were associated with poor treatment-free survival, and i(17q) (p=0.04), unbalanced translocations (p=0.03) and 8q24 gain (p=0.001) were significantly associated with poor overall survival. In a multivariate analysis, 8q24 gain remained a significant predictor of poor overall survival. We conclude that 17p deletion and 8q24 gain have a synergistic impact on outcome, and so patients with this "double-hit" CLL have a particularly poor prognosis. Systematic, targeting screening for 8q24 gain should therefore be considered in cases of 17p- CLL. This article is protected by copyright. All rights reserved.status: publishe

Genomic profiling of Sézary syndrome identifies alterations of key T cell signaling and differentiation genes

Sézary Syndrome is a rare leukemic form of cutaneous T-cell lymphoma defined as erythroderma, adenopathy, and circulating atypical T-lymphocytes. It is rarely curable with poor prognosis. Here we present a multi-platform genomic analysis of 37 Sézary Syndrome patients that implicates dysregulation of the cell cycle checkpoint and T-cell signaling. Frequent somatic alterations were identified in TP53, CARD11, CCR4, PLCG1, CDKN2A, ARID1A, RPS6KA1, and ZEB1. Activating CCR4 and CARD11 mutations were detected in nearly a third of patients. ZEB1, a transcription repressor essential for T-cell differentiation, was deleted in over half of patients. IL32 and IL2RG were over-expressed in nearly all cases. Analysis of T-cell receptor Vβ and Vα expression revealed ongoing rearrangement of the receptors after the expansion of a malignant clone in one third of subjects. Our results demonstrate profound disruption of key signaling pathways in Sézary Syndrome and suggest potential targets for novel therapies