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Jean-jacques Drevon - One of the best experts on this subject based on the ideXlab platform.
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Synchrotron micro-X-ray fluorescence shows sulfur accumulation in the middle cortex of N2-fixing legume Nodules
Protoplasma, 2019Co-Authors: Camille Rivard, Laurie Amenc, Samia Benlahrech, Bouchra Makoudi, Mustapha Teffahi, Hiram A. Castillo-michel, Marine Cotte, Benedikt Lassalle-kaiser, Jean-jacques DrevonAbstract:Sulfur (S) and phosphorus (P) are essential elements for plant growth and physiological functioning. Their deficiency can limit N2 fixation and Nodule development in nodulated legumes. The location of S within Nodule tissues could provide insights into S metabolism and its little-known relationship with N2 fixation. Determinate and indeterminate Nodules were inoculated with specific rhizobia and grown hydroaeroponically under sufficient versus deficient P supplies. Cryogenic and freeze-dried thin sections of Nodules at the flowering stage were mapped using synchrotron micro-X-ray fluorescence to determine the S distribution within the Nodule tissues with a spatial resolution of 2 or 3 μm. A large accumulation of S was found in the middle cortex for both types of Nodules. S was also found in all of the other tissues but with a significantly lower signal. In the middle cortex, P deficiency decreased the S maximum fluorescence intensity by 20% and 25% for the determinate and indeterminate Nodules, respectively. In addition, Mg and Cl maps were also collected showing that Mg was mostly localized in the middle and inner cortex, forming a Mg-rich ring consisting of several cell layers for the determinate Nodules compared with only one cell layer for the indeterminate Nodules. Cl was mainly accumulated in the outer cortex. It is concluded that the accumulation of S in the middle cortex is consistent with its involvement in the ionic equilibrium of the Nodule, and in the osmotic variation of the inner cortex cell-size, which would regulate Nodule permeability to oxygen.
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The Nodule conductance to O2 diffusion increases with phytase activity in N2-fixing [i]Phaseolus vulgaris[/i] L
Plant Physiology and Biochemistry, 2014Co-Authors: Mohamed Lazali, Jean-jacques DrevonAbstract:To understand the relationship between phosphorus use efficiency (PUE) and respiration for symbiotic nitrogen fixation (SNF) in legume Nodules, six recombinant inbred lines of common bean (RIL Phaseolus vulgaris L.), contrasting in PUE for SNF, were inoculated with Rhizobium tropici CIAT899, and grown under hydroaeroponic culture with sufficient versus deficient P supply (250 versus 75 μmol P plant−1 week−1). At the flowering stage, the biomass of plants and phytase activity in Nodules were analyzed after measuring O2 uptake by nodulated roots. Our results show that the P-deficiency significantly increased the phytase activity in Nodules of all RILs though with highest extent for RILs 147, 29 and 83 (ca 45%). This increase in phytase activity was associated with an increase in Nodule respiration (ca 22%) and in use of the rhizobial symbiosis (ca 21%). A significant correlation was found under P-deficiency between Nodule O2 permeability and phytase activity in Nodules for RILs 104, 34 and 115. This observation is to our knowledge the first description of a correlation between O2 permeability and phytase activity of a legume Nodule. It is concluded that the variation of phytase activity in Nodules can increase the internal utilization of P and might be involved in the regulation of Nodule permeability for the respiration linked with SNF and the adaptation to P-deficiency.
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Phosphorus deficiency affected conductance to O2 and ascorbate peroxydase gene expression in Nodules of Phaseolus vulgaris-rhizobia symbiosis
2011Co-Authors: Adnane Bargaz, Jean-jacques Drevon, Mustapha Faghire, Btissam Mandri, Mohamed Farissi, Cherki GhoulamAbstract:Although recent studies have addressed the effects of phosphorus (P) deficiency on Nodule respiration and oxidative stress, little attention has been given to elucidate the relationships between Nodule permeability, Nodule P status, and antioxidative responses. To study these traits, two recombinant inbred lines, namely RILs L115 and L147 were inoculated with Rhizobium tropici CIAT899, and grown in hydroaeroponic culture under P-sufficiency (250) versus P-deficiency (75 μmol P plant-1 week-1) conditions. At the flowering stage, plants and Nodules biomasses, P contents and localization of Nodule ascorbate peroxidase (APX) transcripts were determined after measuring O2 uptake by nodulated roots and Nodule conductance to O2 diffusion (gn). The results showed that P deficiency significantly decreased plant growth and nodulation, with differences between bean genotypes. P deficiency also induced a decrease in Nodule P content (31%) in the sensitive L147 and tolerant line L115, a 42 and 27% reduction in shoots of sensitive and tolerant lines, respectively. Under P-deficiency, gn increased more for the sensitive (39%) than for the tolerant lines (27%). This increase was linked to a rise both in the P levels in Nodules and shoots, as well as in the efficiency of symbiotic nitrogen fixation as determined by Nodule-dependent biomass production for the sensitive lines. Furthermore, positive correlations were found between O2 permeability, gn and P content both in Nodules and shoots (r2 = 0.94** and r2 = 0.96**). Additionally, P-deficiency increased electrolyte leakage, the oxidative stress and the transcripts for ascorbate peroxidase gene in Nodules. The later was more abundant in the inner cortex and the infected cells close to inner cortex. We conclude that gn increased with increases in both Nodule P content and antioxidative responses.
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The Nodule conductance to O-2 diffusion increases with high phosphorus content in the Phaseolus vulgaris-rhizobia symbiosis
Symbiosis, 2011Co-Authors: Adnane Bargaz, - Ghoulam, C., - Faghire, M., H.a. Attar, Jean-jacques DrevonAbstract:Although recent studies have addressed the effects of phosphorus (P) deficiency on Nodule O-2 permeability, little attention has been given to the relationship between Nodule P status and Nodule permeability. To study these traits, four recombinant inbred lines, namely RILs 34, 83, 115, 147 and one local variety (Concesa) of common bean (Phaseolus vulgaris) were inoculated with RhM11 (a native rhizobial strain from Haouz area of Marrakesh), and grown in hydroaeroponic culture under P-sufficiency (250 mu mol P plant(-1) week(-1)) versus P-deficiency (75 mu mol P plant(-1) week(-1)) conditions. At the flowering stage, the biomass of plants and Nodules and their P contents was determined after measuring O-2 uptake by nodulated roots (Conr) and Nodule conductance to O-2 diffusion (g(n)). The results showed that P-deficiency significantly decreased plant growth and nodulation, though there were differences between bean genotypes. P-deficiency also induced a decrease in Nodule P content (31%) in both sensitive (83, 147) and tolerant lines (34, 115), a 42 and 27% reduction in shoots of sensitive and tolerant lines, respectively. These decreases were associated with significant variations in Nodule surface and O-2 permeability among bean genotypes and P-nutrition. Under P-deficiency, gn increased more for the sensitive (39%) than for the tolerant lines (27%). This increase was linked with a rise both in the P levels in Nodules and shoots, as well as in the efficiency of symbiotic nitrogen fixation as determined by Nodule-dependent biomass production for the sensitive lines. Furthermore, positive correlations were found between O-2 permeability, gn and P content both in Nodules and shoots (r(2)=0.94** and r(2)=0.96**). We conclude that Nodule variations in Conr and gn are related to Nodule P content, and may contribute to the adaptation of energy metabolism in N-2-fixing bean Nodules to P-deficiency.
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P-deficiency increases the O-2 uptake per N-2 reduced in alfalfa
Journal of Experimental Botany, 2005Co-Authors: Joachim Schulze, Jean-jacques DrevonAbstract:Nodulated alfalfa (Medicago sativa L. cv. Saranac) plants were grown in hydroponics at P-sufficient and P-deficient supply levels. After 5 weeks of growth, dry matter accumulation, nodulation, total N and P accumulation, as well as 15N2 uptake, were measured. Moreover, the response of Nodule O2-uptake to raising external pO2 was determined in an open-flow measurement system and Nodule permeability was calculated. Plants in the P-deficient supply treatment had a lower P concentration in all organs. In both treatments the highest P concentration was found in Nodules. In the P-deficient supply treatment plants formed less dry matter, had a lower shoot/root ratio, less nodulation, decreased total N accumulation, and lower 15N2 uptake per dry matter Nodule. Nodules in the P-deficient treatment were, on average, smaller and had a higher O2 uptake per N2 reduced, coinciding with increased Nodule permeability and conductance. Thus increased oxygen uptake appears to be a mechanism to adjust Nodule metabolism to P deficiency in indeterminate N2-fixing Nodules such as in alfalfa, as has previously been shown for determinate Nodule forms.
Xiaohui Xie - One of the best experts on this subject based on the ideXlab platform.
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deeplung deep 3d dual path nets for automated pulmonary Nodule detection and classification
Workshop on Applications of Computer Vision, 2018Co-Authors: Wentao Zhu, Chaochun Liu, Wei Fan, Xiaohui XieAbstract:In this work, we present a fully automated lung computed tomography (CT) cancer diagnosis system, DeepLung. DeepLung consists of two components, Nodule detection (identifying the locations of candidate Nodules) and classification (classifying candidate Nodules into benign or malignant). Considering the 3D nature of lung CT data and the compactness of dual path networks (DPN), two deep 3D DPN are designed for Nodule detection and classification respectively. Specifically, a 3D Faster Regions with Convolutional Neural Net (R-CNN) is designed for Nodule detection with 3D dual path blocks and a U-net-like encoder-decoder structure to effectively learn Nodule features. For Nodule classification, gradient boosting machine (GBM) with 3D dual path network features is proposed. The Nodule classification subnetwork was validated on a public dataset from LIDC-IDRI, on which it achieved better performance than state-of-the-art approaches and surpassed the performance of experienced doctors based on image modality. Within the DeepLung system, candidate Nodules are detected first by the Nodule detection subnetwork, and Nodule diagnosis is conducted by the classification subnetwork. Extensive experimental results demonstrate that DeepLung has performance comparable to experienced doctors both for the Nodule-level and patient-level diagnosis on the LIDC-IDRI dataset.
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deeplung deep 3d dual path nets for automated pulmonary Nodule detection and classification
arXiv: Computer Vision and Pattern Recognition, 2018Co-Authors: Wentao Zhu, Chaochun Liu, Wei Fan, Xiaohui XieAbstract:In this work, we present a fully automated lung computed tomography (CT) cancer diagnosis system, DeepLung. DeepLung consists of two components, Nodule detection (identifying the locations of candidate Nodules) and classification (classifying candidate Nodules into benign or malignant). Considering the 3D nature of lung CT data and the compactness of dual path networks (DPN), two deep 3D DPN are designed for Nodule detection and classification respectively. Specifically, a 3D Faster Regions with Convolutional Neural Net (R-CNN) is designed for Nodule detection with 3D dual path blocks and a U-net-like encoder-decoder structure to effectively learn Nodule features. For Nodule classification, gradient boosting machine (GBM) with 3D dual path network features is proposed. The Nodule classification subnetwork was validated on a public dataset from LIDC-IDRI, on which it achieved better performance than state-of-the-art approaches and surpassed the performance of experienced doctors based on image modality. Within the DeepLung system, candidate Nodules are detected first by the Nodule detection subnetwork, and Nodule diagnosis is conducted by the classification subnetwork. Extensive experimental results demonstrate that DeepLung has performance comparable to experienced doctors both for the Nodule-level and patient-level diagnosis on the LIDC-IDRI dataset.\footnote{this https URL}
Marcelle Holsters - One of the best experts on this subject based on the ideXlab platform.
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chalcone reductase homologous transcripts accumulate during development of stem borne Nodules on the tropical legume sesbania rostrata
Planta, 1999Co-Authors: Sofie Goormachtig, Sylvia Herman, Sam Lievens, Marc Van Montagu, Marcelle HolstersAbstract:During a search for genes with induced or enhanced expression in the early stages of development of stem-borne Nodules on Sesbania rostrata, a cDNA with homology to chalcone reductase (CHR) genes was isolated. Here, we describe the characterization of a full-length CHR cDNA (Srchr1) and the pattern of CHR transcript accumulation in stem-borne Nodules. Expression was correlated with both Nodule development and bacterial invasion. In young Nodules, CHR transcripts were observed in cells of the parenchyma, in cells around the Nodule vascular bundles, and in the uninfected cells of the central tissue.
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ethylene mediated phenotypic plasticity in root Nodule development on sesbania rostrata
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Manuel Fernandezlopez, Marc Van Montagu, Wim Dhaeze, Sofie Goormachtig, Marcelle HolstersAbstract:Leguminous plants in symbiosis with rhizobia form either indeterminate Nodules with a persistent meristem or determinate Nodules with a transient meristematic region. Sesbania rostrata was thought to possess determinate stem and root Nodules. However, the nature of Nodule development is hybrid, and the early stages resemble those of indeterminate Nodules. Here we show that, depending on the environmental conditions, mature root Nodules can be of the indeterminate type. In situ hybridizations with molecular markers for plant cell division, as well as the patterns of bacterial nod and nif gene expression, confirmed the indeterminate nature of 30-day-old functional root Nodules. Experimental data provide evidence that the switch in Nodule type is mediated by the plant hormone ethylene.
Wentao Zhu - One of the best experts on this subject based on the ideXlab platform.
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deeplung deep 3d dual path nets for automated pulmonary Nodule detection and classification
Workshop on Applications of Computer Vision, 2018Co-Authors: Wentao Zhu, Chaochun Liu, Wei Fan, Xiaohui XieAbstract:In this work, we present a fully automated lung computed tomography (CT) cancer diagnosis system, DeepLung. DeepLung consists of two components, Nodule detection (identifying the locations of candidate Nodules) and classification (classifying candidate Nodules into benign or malignant). Considering the 3D nature of lung CT data and the compactness of dual path networks (DPN), two deep 3D DPN are designed for Nodule detection and classification respectively. Specifically, a 3D Faster Regions with Convolutional Neural Net (R-CNN) is designed for Nodule detection with 3D dual path blocks and a U-net-like encoder-decoder structure to effectively learn Nodule features. For Nodule classification, gradient boosting machine (GBM) with 3D dual path network features is proposed. The Nodule classification subnetwork was validated on a public dataset from LIDC-IDRI, on which it achieved better performance than state-of-the-art approaches and surpassed the performance of experienced doctors based on image modality. Within the DeepLung system, candidate Nodules are detected first by the Nodule detection subnetwork, and Nodule diagnosis is conducted by the classification subnetwork. Extensive experimental results demonstrate that DeepLung has performance comparable to experienced doctors both for the Nodule-level and patient-level diagnosis on the LIDC-IDRI dataset.
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deeplung deep 3d dual path nets for automated pulmonary Nodule detection and classification
arXiv: Computer Vision and Pattern Recognition, 2018Co-Authors: Wentao Zhu, Chaochun Liu, Wei Fan, Xiaohui XieAbstract:In this work, we present a fully automated lung computed tomography (CT) cancer diagnosis system, DeepLung. DeepLung consists of two components, Nodule detection (identifying the locations of candidate Nodules) and classification (classifying candidate Nodules into benign or malignant). Considering the 3D nature of lung CT data and the compactness of dual path networks (DPN), two deep 3D DPN are designed for Nodule detection and classification respectively. Specifically, a 3D Faster Regions with Convolutional Neural Net (R-CNN) is designed for Nodule detection with 3D dual path blocks and a U-net-like encoder-decoder structure to effectively learn Nodule features. For Nodule classification, gradient boosting machine (GBM) with 3D dual path network features is proposed. The Nodule classification subnetwork was validated on a public dataset from LIDC-IDRI, on which it achieved better performance than state-of-the-art approaches and surpassed the performance of experienced doctors based on image modality. Within the DeepLung system, candidate Nodules are detected first by the Nodule detection subnetwork, and Nodule diagnosis is conducted by the classification subnetwork. Extensive experimental results demonstrate that DeepLung has performance comparable to experienced doctors both for the Nodule-level and patient-level diagnosis on the LIDC-IDRI dataset.\footnote{this https URL}
Carl C Reading - One of the best experts on this subject based on the ideXlab platform.
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the accuracy of thyroid Nodule ultrasound to predict thyroid cancer systematic review and meta analysis
The Journal of Clinical Endocrinology and Metabolism, 2014Co-Authors: Juan P Brito, Carl C Reading, Michael R Gionfriddo, Alaa Al Nofal, Kasey R Boehmer, Aaron L Leppin, Matthew R Callstrom, Tarig Elraiyah, Larry J Prokop, Marius N StanAbstract:Context: Significant uncertainty remains surrounding the diagnostic accuracy of sonographic features used to predict the malignant potential of thyroid Nodules. Objective: The objective of the study was to summarize the available literature related to the accuracy of thyroid Nodule ultrasound (US) in the prediction of thyroid cancer. Methods: We searched multiple databases and reference lists for cohort studies that enrolled adults with thyroid Nodules with reported diagnostic measures of sonography. A total of 14 relevant US features were analyzed. Results: We included 31 studies between 1985 and 2012 (number of Nodules studied 18 288; average size 15 mm). The frequency of thyroid cancer was 20%. The most common type of cancer was papillary thyroid cancer (84%). The US Nodule features with the highest diagnostic odds ratio for malignancy was being taller than wider [11.14 (95% confidence interval 6.6–18.9)]. Conversely, the US Nodule features with the highest diagnostic odds ratio for benign Nodules was ...
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solitary thyroid Nodule comparison between palpation and ultrasonography
JAMA Internal Medicine, 1995Co-Authors: Gerry H Tan, Hossein Gharib, Carl C ReadingAbstract:Objective: To determine the accuracy of clinical palpation in the diagnosis of solitary thyroid Nodule in comparison with ultrasonographic findings. Methods: From a computerized database of 1774 patients with the diagnosis of nodular thyroid disease made from January 1990 through December 1991 at our institution, we retrieved and reviewed the medical records of the 193 patients who underwent ultrasonography of the thyroid (42 patients with multinodular glands on palpation were excluded). Nodules were categorized as "solitary" or "dominant Nodule of a multinodular gland." Concordance rates were measured between results of palpation and ultrasonographic findings. Results: Of 151 patients included in the study, 78 had solitary Nodules on ultrasonography and 73 had multiple Nodules. Of those with multiple Nodules, 49 had two Nodules and 24 had three or more Nodules. Of clinically palpable Nodules, 89% were 1 cm or greater in diameter. In 72% of the patients with multiple Nodules, the other Nodules not identified on palpation were less than 1 cm in diameter. The overall concordance rate between the size of the solitary Nodule or the dominant Nodule in a multinodular gland estimated with clinical palpation and the actual size seen on ultrasonography was 72%. The relationship between multiple Nodules and malignancy was not statistically significant. Conclusions: Our results suggest that (1) a palpable solitary Nodule represents a multinodular gland in about 50% of patients, (2) clinical palpation is less sensitive than thyroid ultrasonography in identifying multiple Nodules, and (3) palpation is reliable only if a Nodule is at least 1 cm in diameter. We recommend that small, occult (impalpable) thyroid Nodules not be considered clinically important; they do not warrant further evaluation unless ultrasonographic features suggest malignancy or the Nodule increases in size. (Arch Intern Med. 1995;155:2418-2423)
