Variabilité génétique du nombre de cellules épidermiques de l’hypocotyle dans l’embryon et identification des QTL contrôlant ce caractère chez la Légumineuse modèle Medicago truncatula

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A Replica Inference Approach to Unsupervised Multi-Scale Image Segmentation

We apply a replica inference based Potts model method to unsupervised image segmentation on multiple scales. This approach was inspired by the statistical mechanics problem of "community detection" and its phase diagram. Specifically, the problem is cast as identifying tightly bound clusters ("communities" or "solutes") against a background or "solvent". Within our multiresolution approach, we compute information theory based correlations among multiple solutions ("replicas") of the same graph over a range of resolutions. Significant multiresolution structures are identified by replica correlations as manifest in information theory overlaps. With the aid of these correlations as well as thermodynamic measures, the phase diagram of the corresponding Potts model is analyzed both at zero and finite temperatures. Optimal parameters corresponding to a sensible unsupervised segmentation correspond to the "easy phase" of the Potts model. Our algorithm is fast and shown to be at least as accurate as the best algorithms to date and to be especially suited to the detection of camouflaged images.Comment: 26 pages, 22 figure

Deciphering the nitrate signaling pathway leading to a reduction of primary root growth in Medicago truncatula

In the model legume Medicago truncatula, nitrate has been shown to inhibit primary root growth through the reduction of root cell elongation. Nitrate, as an essential nutrient, also acts as a signal molecule that is sensed and transduced through a nitrate transporter MtNPF6.8, with RNAi mutants deficient in MtNPF6.8 being insensitive to nitrate [1, 2]. We tested here whether reactive oxygen species (ROS) could be downstream mediators of the nitrate signal since ROS are able to transduce ABA signal in other contexts and also govern the primary root growth. Thus, we analyzed the distribution of ROS (H2O2, O2•−, •OH) and peroxidase activity all along the primary root of seedlings sensitive or insensitive to nitrate using different genotypes of M. truncatula, three wild types and a npf6.8RNAi mutant grown with or without nitrate, to determine whether nitrate modifies ROS and peroxidase patterns. We found that nitrate modified the morphology of the root tip, induced an increase in H2O2, and a decrease in O2•− and •OH in seedlings sensitive to nitrate (R108, A17, and DZA315-16), but not in seedlings insensitive to nitrate (npf6.8RNAi mutant). These results suggest that ROS and peroxidases are downstream mediators in the nitrate signaling pathway. The origin of the change in ROS accumulation in response to nitrate was further investigated following the activity of major enzymes (peroxidase, SOD, Nox) able to interfere with ROS accumulation

Fecal coliform accumulation and depuration in the oyster Crassostrea gigas

Experiments on fecal coliform accumulation and depuration in the oyster Crassostrea gigas were performed under two seasons (winter, summer), under various conditions of bacterial concentration (from 101 to 103 CFU ml-1) and suspended matter (10 to 50 mg l-1). Contamination process in the bivalve is mainly influenced by the bacterial density in the seawater. Influence of suspended matter concentration was less effective. Maximal bacterial accumulation was reached within 30 min. in summer (18 °C) and 5 hours in winter (11 °C). Concerning depuration process a 10 fold decrease of initial contamination required 3 hours and a 100 fold decrease was achieved within 10 hours. Time required for depuration was mainly dependent on the initial bacterial concentration in the oyster

Systemic and immune manifestations in myelodysplasia: a multicenter retrospective study

OBJECTIVE: The presence of systemic and/or immune manifestations in myelodysplasia has been currently reported. The influence of these manifestations on the natural outcome of myelodysplastic syndrome has to be considered. We present a multicenter retrospective study (2002-2009) of patients with myelodysplastic syndrome disclosing systemic and/or immune manifestations. METHODS: Forty-six patients with myelodysplasia presenting with systemic and/or immune manifestations were compared in terms of survival with 189 patients with myelodysplasia lacking these features. RESULTS: The clinical picture in these cases consisted of fever (13%), arthralgia or arthritis (13%), and cutaneous manifestations (67%). Four cases of systemic vasculitis have been reported in our series, and they have a worse prognosis. Immune anomalies were recorded in 29% of the cases, and the presence of cryoglobulins was also associated with a worse prognosis. CONCLUSION: A difference in survival between patients with myelodysplastic syndrome with systemic manifestations and patients lacking these manifestations has been observed in the presence of systemic vasculitis and/or cryoglobulins

Cell elongation instead cell number becomes the predominant factor influencing genotypic differences in Medicago truncatula hypocotyl length under abiotic stress

International audienc