Geminivirus C2 protein represses genes involved in sulphur assimilation and this effect can be counteracted by jasmonate treatment

Geminiviruses are plant viruses that infect a broad range of crops and cause extensive losses worldwide, having an important economic impact. C2, a multifunctional pathogenicity factor encoded by geminiviruses, has been recently shown to suppress the responses to jasmonates in the host plant, which might at least partially explain its well-established role in pathogenicity. Sulphur is one of the essential macro-elements for plant life, and is considered to have a role in plant defence, in a phenomenon named sulphur-induced resistance (SIR) or sulphur-enhanced defence (SED). In this work, we show that geminivirus C2 protein represses the expression of genes involved in the sulphur assimilation pathway in Arabidopsis, but, interestingly, this effect can be neutralized by exogenous jasmonate treatment. These preliminary results may raise the idea that geminiviruses might be affecting sulphur metabolism, and maybe counteracting SIR/SED, through the manipulation of the jasmonate signalling pathway, which would define a novel strategy in plant-virus interactions and may unveil SIR/SED as an important player in the plant defence against viruses.Ministerio de Ciencia y Innovación/FEDER AGL2007-66062-C02-02/AGR AGL2010-22287-CO2European Regional Development Fund (ERDF) BIO2010-15201Junta de Andalucía BIO­27

Cd localisation and speciation in a contaminated sediment and in the Znand Cd hyperaccumulating plant Arabidopsis halleri

International audienceThe purpose of this work was to characterise the chemical speciation of Cd in a Zn- and Cd-contaminated dredged sediment subjected to a phytoremediation treatment with the hyperaccumulator plant Arabidopsis halleri

Fate of cadmium in the rhizosphere of Arabidopsis halleri grown in a contaminated dredged sediment

International audienceIn regions impacted by mining and smelting activities, dredged sediments are often contaminated with metals. Phytotechnologies could be used for their management, but more knowledge on the speciation of metals in the sediment and on their fate after colonization by plant roots is needed. This work was focused on a Zn, Cd-contaminated contaminated dredged sediment from the Scarpe river (North of France). Zn, Cd hyperaccumulating plants Arabidopsis halleri from metallicolous and non metallicolous origin were grown on the sediment for five months in a pot experiment. The nature and extent of the modifications in Cd speciation with or without plant were determined by electron microscopy, micro X-ray fluorescence and bulk and micro X-ray absorption spectroscopy. In addition, changes in Cd exchangeable and bioavailable pools were evaluated, and Cd content in leachates was measured. Finally, Cd plant uptake and plant growth parameters were monitored. In the original sediment, Cd was present as a mixed Zn, Cd, Fe sulfide. After five months, although pots still contained reduced sulfur, Cd-bearing sulfides were totally oxidized in vegetated pots, whereas a minor fraction (8%) was still present in non vegetated ones. Secondary species included Cd bound to O-containing groups of organic matter and Cd phosphates. Cd exchangeability and bioavailability were relatively low and did not increase during changes in Cd speciation, suggesting that Cd released by sulfide oxidation was readily taken up with strong interactions with organic matter and phosphate ligands. Thus, the composition of the sediment, the oxic conditions and the rhizospheric activity (regardless of the plant origin) created favourable conditions for Cd stabilization. However, it should be kept in mind that returning to anoxic conditions may change Cd speciation, so the species formed cannot be considered as stable on the long term

Is phytoextraction a suitable green treatment for metal-contaminated sediments ?

International audienceThe cleaning of waterways by regular dredging generates great volumes of sediments and, owing to human activities, these sediments often contain large amounts of metals. These materials are usually spread on landfill sites. Phytoremediation could be a stategy for the reclamation of these polluted sediments. To our knowledge, phytoextraction with hyperaccumulating plants has been few tested on contaminated sediment. This work focuses on the mechanisms of Cd accumulation in Arabidopsis halleri, a Cd and Zn hyperaccumulator, and the effects of this species on a metal polluted sediment

Coonrad-Morrey total elbow arthroplasty for patients with rheumatoid arthritis: 54 prostheses reviewed at 7 years' average follow-up (maximum, 16 years)

BACKGROUND: Total elbow arthroplasty is a therapeutic option for severe rheumatoid arthritis. We hypothesized that the semiconstrained characteristics of the Coonrad-Morrey prosthesis do not compromise the survival rate of the implant in a rheumatoid elbow. METHODS: Between 1997 and 2012, there were 54 Coonrad-Morrey total elbow prostheses performed for rheumatoid arthritis in 46 patients. Minimum follow-up was 2 years. There were 35 women and 11 men with a mean age of 60 years (29-83 years). According to the Mayo classification for rheumatoid elbow, there were 30 type IIIA, 21 type IIIB, and 3 type IV. The surgical procedure was the same for all patients. Survivorship was assessed with use of the Kaplan-Meier method, with revision surgery as the end point. RESULTS: The survival rate was 97% (95% confidence interval, 83.6-99.6) at 5 years and 85% (95% confidence interval, 68.3-93.7) at 10 years. At an average of 7 years of follow-up (2-16 years), the mean Mayo Elbow Performance Score was 91 points (55-100 points), and the shortened version of the Disabilities of the Arm, Shoulder, and Hand score was 34 points (0-75 points). There was a significant improvement in Mayo Elbow Performance Score and in all range of motion at latest follow-up in comparison to preoperative values (P < .0001). Radiolucencies were observed in 6 cases around the humeral component and in 6 cases around the ulnar component. Bushing wear was observed in 16 cases (29%). There were 14 complications (26%). Revisions were performed in 6 of them (11%). CONCLUSION: The Coonrad-Morrey prosthesis provides satisfactory results with follow-up. The rate of complications remains high even if the rate of implant revision stayed low

Comparative expression of cell wall related genes in four maize RILs and one parental line of variable lignin content and cell wall degradability

A comparison of gene expression in maize between the parental line F271 and four RILs derived from the cross F288 x F271 was investigated based on hybridization on the 17,555 probes Affymetrix micro-array, targeting nearly one third of the genes present in maize genomes. The parental line had unfavorable alleles for cell wall degradability traits at the major QTL position in bin 6.06, while the set of RILs had both the favorable allele and high cell wall degradability. 360 genes were differentially expressed in the four RIL in comparison to F271, including nine genes underlying the major QTL position and 36 underlying two other QTL positions. However, their proposed function (whenever is described) do not allow us to firmly consider their involvement in the observed variation of cell wall related traits. Only a few genes involved in monolignol biosynthesis or polymerization located elsewhere in the genome were differentially expressed between the four RILs and F271, corroborating with the fact that these genes are probably not involved in major determinants of cell wall degradability in the studied set of lines. Among the investigated regulation factors, three ZmMYB, one NAC and one C3HC4 zinc finger were differentially expressed between the four RILs and F271, but they were not located in bin 6.06. Notwithstanding, the obtained results especially strengthened the probable involvement of these genes in maize secondary wall assembly and/ or lignification

Adult Low-Hypodiploid Acute Lymphoblastic Leukemia Emerges from Preleukemic TP53-Mutant Clonal Hematopoiesis

UNLABELLED Low hypodiploidy defines a rare subtype of B-cell acute lymphoblastic leukemia (B-ALL) with a dismal outcome. To investigate the genomic basis of low-hypodiploid ALL (LH-ALL) in adults, we analyzed copy-number aberrations, loss of heterozygosity, mutations, and cytogenetics data in a prospective cohort of Philadelphia (Ph)-negative B-ALL patients (n = 591, ages 18-84 years), allowing us to identify 80 LH-ALL cases (14%). Genomic analysis was critical for evidencing low hypodiploidy in many cases missed by cytogenetics. The proportion of LH-ALL within Ph-negative B-ALL dramatically increased with age, from 3% in the youngest patients (under 40 years old) to 32% in the oldest (over 55 years old). Somatic TP53 biallelic inactivation was the hallmark of adult LH-ALL, present in virtually all cases (98%). Strikingly, we detected TP53 mutations in posttreatment remission samples in 34% of patients. Single-cell proteogenomics of diagnosis and remission bone marrow samples evidenced a preleukemic, multilineage, TP53-mutant clone, reminiscent of age-related clonal hematopoiesis. SIGNIFICANCE We show that low-hypodiploid ALL is a frequent entity within B-ALL in older adults, relying on somatic TP53 biallelic alteration. Our study unveils a link between aging and low-hypodiploid ALL, with TP53-mutant clonal hematopoiesis representing a preleukemic reservoir that can give rise to aneuploidy and B-ALL. See related commentary by Saiki and Ogawa, p. 102. This article is highlighted in the In This Issue feature, p. 101

The zinc finger protein PtaZFP2 negatively controls stem growth and gene expression responsiveness to external mechanical loads in poplar

Mechanical cues are essential signals regulating plant growth and development. In response to wind, trees develop a thigmomorphogenetic response characterized by a reduction in longitudinal growth, an increase in diameter growth, and changes in mechanical properties. The molecular mechanisms behind these processes are poorly understood. In poplar, PtaZFP2, a C2H2 transcription factor, is rapidly up-regulated after stem bending. To investigate the function of PtaZFP2, we analyzed PtaZFP2-overexpressing poplars (Populus tremula 9 Populus alba). To unravel the genes downstream PtaZFP2, a transcriptomic analysis was performed. PtaZFP2-overexpressing poplars showed longitudinal and cambial growth reductions together with an increase in the tangent and hardening plastic moduli. The regulation level of mechanoresponsive genes was much weaker after stem bending in PtaZFP2-overexpressing poplars than in wild-type plants, showing that PtaZFP2 negatively modulates plant responsiveness to mechanical stimulation. Microarray analysis revealed a high proportion of down-regulated genes in PtaZFP2-overexpressing poplars. Among these genes, several were also shown to be regulated by mechanical stimulation. Our results confirmed the important role of PtaZFP2 during plant acclimation to mechanical load, in particular through a negative control of plant molecular responsiveness. This desensitization process could modulate the amplitude and duration of the plant response during recurrent stimuli

Characterization of a cinnamoyl-CoA reductase 1 (CCR1) mutant in maize: effects on lignification, fibre development, and global gene expression

Cinnamoyl-CoA reductase (CCR), which catalyses the first committed step of the lignin-specific branch of monolignol biosynthesis, has been extensively characterized in dicot species, but few data are available in monocots. By screening a Mu insertional mutant collection in maize, a mutant in the CCR1 gene was isolated named Zmccr1–. In this mutant, CCR1 gene expression is reduced to 31% of the residual wild-type level. Zmccr1– exhibited enhanced digestibility without compromising plant growth and development. Lignin analysis revealed a slight decrease in lignin content and significant changes in lignin structure. p-Hydroxyphenyl units were strongly decreased and the syringyl/guaiacyl ratio was slightly increased. At the cellular level, alterations in lignin deposition were mainly observed in the walls of the sclerenchymatic fibre cells surrounding the vascular bundles. These cell walls showed little to no staining with phloroglucinol. These histochemical changes were accompanied by an increase in sclerenchyma surface area and an alteration in cell shape. In keeping with this cell type-specific phenotype, transcriptomics performed at an early stage of plant development revealed the down-regulation of genes specifically associated with fibre wall formation. To the present authors’ knowledge, this is the first functional characterization of CCR1 in a grass species

Etude du devenir du cadmium dans un sédiment de curage fortement contaminé et des mécanismes d'accumulation du cadmium chez Arabidopsis halleri

The cleaning of waterways by regular dredging generates great volumes of sediments which often contain large amounts of metals. For some of them, a treatment by phytoextraction could be considered. The first part of this work focuses on the fate of Cd present in a metal-polluted dredged sediment during the culture of Arabidopsis halleri, a Zn and Cd hyperaccumulating plant. In this purpose, a five month pot experiment was done. Cd contents in the sediment, in the aerial parts of plant and in the leachates were measured each month in planted and non planted pots. The presence of plants decreases the amount of leached Cd, but does not influence the Cd exchangeable fraction and the Cd phytoavailable pool. Cd speciation in the sediment was studied by EXAFS and µXANES spectroscopy, Cd localization by µXRF and SEM-EDX, and Cd bioavailability by DGT and Ca(NO3)2 extraction. Before culture, Cd is present as mixed Zn, Cd and Fe sulphide of. After 5 months of culture, this species is totally oxidized in presence of plants and almost totally in the control pot without plant. Secondary Cd species include Cd- organic acid complexes and Cd-phosphate. The second part of this work focuses on the mechanisms of Cd accumulation in the aerial parts of A. halleri. After hydroponic culture, the study of the aerial parts by autoradiography using 109Cd showed that Cd was stored both in young and mature leaves, the latter showing a metal enrichment in the peripheral parts. The EXAFS study of the leaves showed that Cd was predominantly bound to COOH/OH–type organic ligands, and to a minor extent to thiol ligands.La maintenance des voies navigables par dragage génère de grands volumes de sédiments, souvent contaminés en métaux. Pour certains d'entre eux, un traitement par phytoextraction pourrait être envisagé. Le premier volet de ce travail vise à étudier le devenir du Cd présent dans un sédiment de curage contaminé par des métaux lors de la culture d'A. halleri, plante hyperaccumulatrice de Zn et Cd. Pour cela, un suivi des teneurs en Cd a été réalisé dans le sédiment, les parties aériennes de la plante et les lixiviats lors de la culture en pot. La présence de plantes diminue la quantité de Cd lixivié, mais ne modifie ni la fraction échangeable ni le pool phytodisponible en Cd. La spéciation a été étudiée par spectroscopie EXAFS et µXANES, la localisation par µXRF et MEB-EDX, et la biodisponibilité par DGT et extraction au Ca(NO3)2. Avant culture, le Cd est présent sous forme d'un sulfure mixte de Zn, Cd et Fe. Après 5 mois de culture, cette espèce est totalement oxydée en présence de plantes et presque totalement dans les pots sans plante. Les espèces de Cd néoformées sont des complexes Cd-acides organiques et du Cd-phosphate. Le second volet de ce travail porte sur les mécanismes d'accumulation du Cd dans les parties aériennes d'A. halleri. Après culture en hydroponie, l'analyse des parties aériennes par autoradiographie en utilisant 109Cd montre que le métal est transféré aussi bien dans les feuilles jeunes que les matures, ces dernières montrant un enrichissement des tissus périphériques. L'analyse des feuilles par spectroscopie EXAFS a montré que le Cd était lié principalement à des ligands organiques de type COOH/OH, et de façon minoritaire à des ligands de type thiols