FiRe and microarrays: a fast answer to burning questions

FiRe is a user-friendly Excel® macro designed to survey microarray data rapidly. This software interactively assembles data from different experiments and produces lists of candidate genes according to patterns of gene expression. Furthermore, macros bundled with FiRe can compare lists of genes, merge information from different spreadsheets, link candidates to information available from web-based databases, and produce heat-maps for easy visualization of microarray data. FiRe is freely available at http://www.unifr.ch/plantbio/FiRe/main.html

Lipid Nanocapsules Loaded with Rhenium-188 Reduce Tumor Progression in a Rat Hepatocellular Carcinoma Model

International audienceBACKGROUND: Due to their nanometric scale (50 nm) along with their biomimetic properties, lipid nanocapsules loaded with Rhenium-188 (LNC(188)Re-SSS) constitute a promising radiopharmaceutical carrier for hepatocellular carcinoma treatment as its size may improve tumor penetration in comparison with microspheres devices. This study was conducted to confirm the feasibility and to assess the efficacy of internal radiation with LNC(188)Re-SSS in a chemically induced hepatocellular carcinoma rat model. METHODOLOGY/PRINCIPAL FINDINGS: Animals were treated with an injection of LNC(188)Re-SSS (80 MBq or 120 MBq). The treated animals (80 MBq, n = 12; 120 MBq, n = 11) were compared with sham (n = 12), blank LNC (n = 7) and (188)Re-perrhenate (n = 4) animals. The evaluation criteria included rat survival, tumor volume assessment, and vascular endothelial growth factor quantification. Following treatment with LNC(188)Re-SSS (80 MBq) therapeutic efficiency was demonstrated by an increase in the median survival from 54 to 107% compared with control groups with up to 7 long-term survivors in the LNC(188)Re-SSS group. Decreased vascular endothelial growth factor expression in the treated rats could indicate alterations in the angiogenesis process. CONCLUSIONS/SIGNIFICANCE: Overall, these results demonstrate that internal radiation with LNC(188)Re-SSS is a promising new strategy for hepatocellular carcinoma treatment

Etude de l'embryogenèse chez Arabidopsis thaliana (caractérisation fonctionnelle et moléculaire de EMB506 et AKR, deux gènes nucléaires codant pour des protéines plastidiales)

Le gène EMB506 code pour une protéine chloroplastique essentielle au développement de l'embryon chez Arabidopsis thaliana. Par complémentation de la mutation emb506 au cours de l'embryogenèse uniquement, un phénotype post-embryonnaire de chlorose des inflorescences a pu être observé. La protéine EMB506 contient un domaine ankyrine, ce qui suggère l'existence de partenaires spécifiques. Chez Arabidopsis seule la protéine AKRP, codée par le gène AKR, présente un domaine semblable. Afin d'identifier les partenaires reconnus par EMB506, une banque d'ADNc de siliques immatures a été criblée par la technique du double-hybride chez la levure. Un seul interactant a été isolé : AKRP. L'utilisation de délétions a montré que les deux partenaires s'associent via leurs domaines ankyrine respectifs.Dans l'optique de pouvoir comparer les rôles d'EMB506 et d'AKRP, et d'évaluer la possibilité que les deux protéines interagissent in vivo, plusieurs approches ont été suivies. Un mutant akr a été isolé. Il présente un phénotype d'arrêt au stade globulaire de l'embryogenèse, comme le mutant emb506. La complémentation du mutant akr pendant l'embryogenèse uniquement, grâce à la construction ABI3::AKR, a permis d'obtenir des plantes homozygotes akr/akr présentant des variégations, indiquant un effet d'AKRP sur le développement du plaste. Une fusion traductionnelle avec la GFP a démontré qu'AKRP était adressé au plaste, comme EMB506. La caractérisation de lignées EMB506::GUS et AKR::GUS, ainsi que du patron d'expression de AKRP par western-blot a également été entreprise. Au total, ces données suggèrent que EMB506 et AKRP sont impliqués dans les mêmes fonctions pendant et après l'embryogenèse,The EMB506 gene codes for a plastidial protein required for embryo development in Arabidopsis thaliana. Complementing the emb506 mutation only during embryogenesis resulted in a post-embryonic chlorotic phenotype of inflorescences. The EMB506 protein contains an ankyrin repeat domain which suggests the existence of specific interacting proteins. In Arabidopsis only AKRP coded by the AKR gene, displays a similar domain. In order to identify partners recognized by EMB506, a cDNA library from immature siliques was screened using the two-hybrid system in yeast. Only one interacting protein was discovered : AKRP. Using domain deletions it was shown that these two proteins bind each other via their respective ankyrin repeat domain.With the aim of comparing EMB506 and AKRP roles, and to assess the possibility that these two proteins may interact in vivo, several approaches were used. An akr mutant was isolated which exhibits a globular stage developmental arrest, like the emb506 mutant. Complementing this mutant during embryogenesis only, by the ABI3::AKR construct, yielded homozygous akr/akr plants displaying variegations, which suggests an effect of AKRP on plastid development. A translational fusion with GFP demonstrated that AKRP is targeted to the plastid, again like EMB506. Characterization of some EMB506::GUS and AKR::GUS lines, as well as the study of the AKRP protein expression profile, was undertaken. In conclusion, these data suggest that EMB506 and AKRP are involved in the same functions during and after embryogenesis, and underline the importance of the plastid in embryo development.PERPIGNAN-BU Sciences (661362101) / SudocSudocFranceF

Characterisation of the tolerance to the beet leafhopper transmitted virescence agent phytoplasma in the PI128655 accession of <em>Solanum peruvianum</em>

In 1992, Thomas and Hassan reported an apparent immunity and tolerance to the beet leafhopper transmitted virescence agent (BLTVA) phytoplasma in the PI128655 accession of Solanum peruvianum (Plant Disease 76: 139). We revisited this interaction in an effort to better characterize the bases of plant resistance and tolerance to phytoplasmas. After challenge with a BLTVA strain, plants of the PI128655 accession fell into two distinct symptom-based groups, termed class I and class II. Class II plants displayed symptoms on the vegetative parts and phloem hyperplasia, whereas class I plants showed symptoms only on the inflorescence parts, and no phloem hyperplasia. Plants of both classes hosted similar titres of BLTVA, demonstrating that the lower symptom severity in class I plants was due to tolerance rather than resistance. However, this tolerance was not effective against all phytoplasmas, as both classes of plants were equally susceptible to a stolbur phytoplasma strain. A genetic analysis suggested that the BLTVA tolerance of class I plants was monogenic. Finally, a reciprocal graft experiment showed that the virulence of the BLTVA strain seemed to increase after propagation through class II plants. These results provide valuable insights on the tolerance of plants to phytoplasma diseases, and highlight the usefulness of the S. peruvianum/BLTVA experimental pathosystem

Comparison of Current Methods for Signal Peptide Prediction in Phytoplasmas

Although phytoplasma studies are still hampered by the lack of axenic cultivation methods, the availability of genome sequences allowed dramatic advances in the characterization of the virulence mechanisms deployed by phytoplasmas, and highlighted the detection of signal peptides as a crucial step to identify effectors secreted by phytoplasmas. However, various signal peptide prediction methods have been used to mine phytoplasma genomes, and no general evaluation of these methods is available so far for phytoplasma sequences. In this work, we compared the prediction performance of SignalP versions 3.0, 4.0, 4.1, 5.0 and Phobius on several sequence datasets originating from all deposited phytoplasma sequences. SignalP 4.1 with specific parameters showed the most exhaustive and consistent prediction ability. However, the configuration of SignalP 4.1 for increased sensitivity induced a much higher rate of false positives on transmembrane domains located at N-terminus. Moreover, sensitive signal peptide predictions could similarly be achieved by the transmembrane domain prediction ability of TMHMM and Phobius, due to the relatedness between signal peptides and transmembrane regions. Beyond the results presented herein, the datasets assembled in this study form a valuable benchmark to compare and evaluate signal peptide predictors in a field where experimental evidence of secretion is scarce. Additionally, this study illustrates the utility of comparative genomics to strengthen confidence in bioinformatic predictions

Genetic control of the response to a 'Candidatus Phytoplasma trifolii' strain by Solanum peruvianum

A report describing the strong resistance and tolerance of the accession PI128655 of Solanum peruvianum to two BLTVA strains (beet leafhopper transmitted virescence agent; `Candidatus Phytoplasma trifolii') was published almost twenty years ago. This work was revisited using another BLTVA strain and the PI128655 plants. No resistance or tolerance was observed. Instead the plants showed either one of two different sets of symptoms. A genetic control of the response to the phytoplasma isolated by the PI128655 plants was demonstrated using clones of host plants. However we obtained experimental evidence that the BLTVA isolate lacked homogeneity or stability, which could also explain the occurrence of two sets of symptoms. A possible hypothesis is that the PI128655 plants, by interfering with the competition between the 'components' of the BLTVA isolate, can alter the final composition of the phytoplasma population and therefore influence the induced symptoms

Interaction entre le phytoplasme du stolbur et la tomate : recherche de lignées résistantes et effet de l'activation des voies de signalisation dépendantes du salicylate et du jasmonate

National audienc

Genetic control of the response to a 'Candidatus Phytoplasma trifolii' strain by Solanum peruvianum

International audienceA report describing the strong resistance and tolerance of the accession PI128655 of Solanum peruvianum to two BLTVA strains (beet leafhopper transmitted virescence agent; `Candidatus Phytoplasma trifolii') was published almost twenty years ago. This work was revisited using another BLTVA strain and the PI128655 plants. No resistance or tolerance was observed. Instead the plants showed either one of two different sets of symptoms. A genetic control of the response to the phytoplasma isolated by the PI128655 plants was demonstrated using clones of host plants. However we obtained experimental evidence that the BLTVA isolate lacked homogeneity or stability, which could also explain the occurrence of two sets of symptoms. A possible hypothesis is that the PI128655 plants, by interfering with the competition between the 'components' of the BLTVA isolate, can alter the final composition of the phytoplasma population and therefore influence the induced symptoms