Search

International audience; Interactions among plants have been long recognized as a major force driving plant community dynamics and crop yield. Surprisingly, our knowledge of the ecological genetics associated with variation of plant-plant interactions remains limited. In this opinion article by scientists from complementary disciplines, the international PLANTCOM network identified four timely questions to foster a better understanding of the mechanisms mediating plant assemblages. We propose that by identifying the key relationships among phenotypic traits involved in plant-plant interactions and the underlying adaptive genetic and molecular pathways, while considering environmental fluctuations at diverse spatial and time scales, we can improve predictions of genotype-by-genotype-by-environment interactions and modeling of productive and stable plant assemblages in wild habitats and crop fields.

Glycolipids are promising nonionic biosurfactants with a wide range of application. In contrast to the traditional surfactants from fossil origin, they are not only exhibiting excellent surfactant and emulsifying properties but are in addition biodegradable and non-toxic to the environment. Glycolipids can be produced by microbial fermentation, by chemical or enzymatical synthesis using renewable resources. In this review, strengths and weaknesses of each production method are compared and enzymatic synthesis is highlighted as the method of choice for the tailor-made synthesis of a wide range of novel glycolipids. As for enzymatical and chemical synthesis solvents with low water activity are needed to favor condensation instead of the hydrolysis reaction, organic solvents or ionic liquids are commonly used. However, the unusual deep eutectic solvent system might be a green alternative worth to consider. In terms of enzymatic catalysis, lipases are well known in literature and already widely used for the production of sugar-acyl-esters. However, β-glucosidases can be alternatively used for glycolipid synthesis which is far less studied. The abilities of both enzymes for glycolipid synthesis are therefore compared and discussed.

Ionic organometallic ruthenium(II) complexes, [η5-CpRu(PPh3) (1,10-phenanthroline)]+Cl− 1, [η5-CpRu(PPh3) (4,7-dimethyl, 1,10-phenanthroline)]+Cl− 2, and [η5-CpRu(PPh3) (1,10-phenanthroline-5-amine)]+Cl− 3 have been synthesized and characterized. The molecular structures of the complexes 1 and 2 were confirmed by single-crystal X-ray structure analysis. Cytotoxicity assays demonstrated that these compounds show significant toxicity against NIH3T3 and Raw 264 cancer cell lines at low concentration. These complexes have the property of DNA binding cleavage.

a b s t r a c t Mantle plumes have been increasingly studied in the past years, yet they remain not well understood. While geophysical approaches attempt to locate the depth of sources, petrological approaches characterize the nature of the materials that melt and geochemical approaches trace their history and origin. However, combined studies remain rare while they could provide strong constraints on the processes that give rise to mantle plumes. Here we present a new model that combines petrological and geochemical approaches to constrain the nature of source materials, their temperature of melting, their composition and their age. We focus on Gambier Island, Pitcairn chain in Polynesia because it has the advantage of combining two important features, (a) most lavas are tholeiites, a necessary feature to perform an accurate petrological modeling that can be compared to other plumes and (b) it belongs to the Pitcairn Chain, whose composition varies through time and samples today the extreme EM1-type source. We present geochemical analyses as well as Sr-Nd-Pb-Hf isotopes of lavas and high-precision olivine analyses. Using in situ olivine analyses and REE modeling, we constrain the composition of the mantle source (5% recycled oceanic crust - 95% peridotite), how both components melt (25-30% versus 0.5-1.5%) and we estimate the temperature of Gambier source at about 1400 ◦ C, a rather low temperature compared to Hawaii for example. We also constrain both the age and the nature of the recycled material using the isotopic data. They require the presence of about 3% sediment associated to recycled basalt in the pyroxenitic component and its age is about 1.5 Gyr. We also attribute the marked Nb-Ta positive anomalies and the elevated Ce/Pb ratios to the presence of recycled basalt in the mantle source. These features resemble typical HIMU lavas but the younger age of the recycled material together with the presence of sediment in the plume source explains the lower Pb isotopic ratios. The clear isotopic change between Gambier and Pitcairn Islands suggests that the plume source changed radically within 5 Ma. More generally, our new data and model suggest that the FOZO composition as sampled by Gambier lavas does not necessarily represent a large and rather primitive mantle source.

Branched broomrape ( Orobanche ramosa ) has displayed a worrying expansion in winter oilseed rape crops over the last decade in France. The efficacy of both plant defence activators, acibenzolar- S -methyl (ASM, 0.05 g a.i. L −1 ) and potassium phosphonate (1 g a.e. L −1 ) in the induction of oilseed rape resistance was evaluated under controlled conditions through repeated bi-weekly applications as foliar sprays or soil drenches. These activator concentrations did not affect the growth of the non-infected oilseed rape. ASM slightly reduced broomrape seed germination while no direct effect was observed for potassium phosphonate. Regardless of the application method, potassium phosphonate did not induce resistance, as shown by the high number of broomrape attachments per treated plant and the near 50% reduction in biomass observed in the infected oilseed rape, whether treated or not. On the contrary, both foliar and soil applications of ASM reduced broomrape attachment by 70% and prevented the loss of crop biomass.

Heavy infestation of faba bean fields by Orobanche foetida is an emerging problem in Tunisia. Field trials during three consecutive crop seasons demonstrated the resistance of three genotypes to O. foetida , including the cv. Baraca, selected for resistance to O. crenata , and two Tunisian breeding lines, Bader and XBJ90.03-16-1-1-1. Resistant genotypes displayed a parasitism index two-fold lower than that of the susceptible checks. They carried 2–8 times less of tubercle attachments and 2–3 times less of emerged parasite spikes at pod setting stage and at crop maturity, respectively. Seed-yield losses by parasitism reached 90% for the susceptible checks and were two-fold lower for the resistant genotypes. Parasitism affected negatively the protein/starch ratio of seeds of both susceptible and resistant genotypes. The line XBJ90.03-16-1-1-1 was the best candidate for registration because of better productivity in non-infested fields and production of high-weight seeds.

Background: Early identification of the biological activity of luteinizing hormone-releasing hormone (LHRH) paved the way for the synthesis of analogues with enhanced potency and biological properties. Early testing in animal models and humans provided insight into the potential clinical uses of these substances, and, within 10 years, LHRH-agonist therapy had become available for use in patients with advanced prostate cancer (PC). Over time, the role of LHRH-agonist therapy has expanded to include use as part of multimodal treatment regimens throughout the course of the disease. Objectives: This article reviews the discovery and development of LHRH agonists and summarizes the clinical evidence for their efficacy in PC. Methods: Relevant clinical studies were identified through searches of the English-language literature indexed on MEDLINE through May 2006. The main search terms were prostate cancer and LHRH agonist. Results: Results of the initial therapeutic trials of sustained-release depot formulations of LHRH agonists in patients with PC were reported in the mid-1980s, indicating that these agents were effective and well tolerated in improving clinical symptoms and producing medical castration. Longer-term studies and subsequent meta-analyses of randomized controlled trials in patients with advanced PC found no significant differences in overall survival when single-therapy androgen suppression was achieved through the use of LHRH-agonist therapy or orchiectomy. Randomized trials have reported significant improvements in diseasefree and overall survival in patients with locally advanced or high-grade PC treated with LHRH agonists in addition to radiotherapy. Several prospective randomized trials have reported decreases in rates of positive surgical margins with short-term (6 weeks to 4 months) neoadjuvant LHRH-agonist therapy in patients with stage T1 to T3a PC undergoing prostatectomy. Definitive comparisons of immediate and delayed treatment in patients with biochemical relapse have not been reported. However, the results of several studies suggest that immediate LHRH-agonist therapy (or orchiectomy) may improve the course of disease progression and survival. The risks of long-term treatment (eg, osteoporosis; fracture; anabolic loss of muscle mass, with a tendency toward weight gain) must be considered carefully in patients who are likely to receive chronic LHRH-agonist therapy. Intermittent schedules have been developed to reduce the adverse effects associated with LHRH-agonist therapy; some reports support sparing effects on bone and muscle mass and relative improvements in toxicities during off-therapy periods, whereas others have documented continuing decreases in bone mineral density (BMD), with the rate of bone loss highest during the early cycles of therapy. Bisphosphonate therapy has been shown to increase BMD in patients with PC and may therefore be beneficial when overt symptoms of osteopenia or osteoporosis are present. Conclusions: LHRH-agonist therapy has been the mainstay of treatment for advanced PC for >20 years. Clinical evidence supports expanding use of these agents at an earlier stage of disease and as part of multimodal regimens that include radiotherapy. There is a need for further study of the efficacy of adjuvant LHRH-agonist therapy along with prostatectomy, in patients with biochemical failure, in intermittent regimens, and in conjunction with cytotoxic therapies in late-stage disease.

The reported results demonstrate that Orobanche ramosa exudates, released over seed germination, are involved in the early tomato perception of this pathogen. For the first time, a 2642 bp cDNA displaying characteristic features of wall-associated kinase receptor was cloned and characterized in tomato. Expression studies revealed that transcript level of this Lycopersicon esculentum wall-associated kinase (LeWAK) increased early in tomato roots and in cell suspensions challenged with Orobanche ramosa. The involvement of LeWAK as a sensor of cell wall alterations during broomrape attack and the subsequent activation of defense reactions is discussed in this paper.

A suppression subtractive hybridization strategy was used to identify genes that were induced 2 h after infection of Arabidopsis thaliana by broomrape (Orobanche ramosa) seedlings. Among these genes, the expression of twelve was analysed from the first hour to the seventh day of this compatible interaction by cDNA blot analyses. The twelve genes showed a transient expression, which occurred in seven cases as early as the first or second hour of interaction and ended 2 or 3 h later. Most of the proteins encoded by these genes are already known to be involved in different A. thaliana response pathways to pathogen attack. The first two genes to be induced (Rc kinase and ACaM5) encoded a receptor and a calmodulin, and could be involved in signal transduction. The two following genes encoding a sucrose carrier (SUC1) and a protein with a pectin methylesterase inhibitor domain were found to be overexpressed; their roles are consistent with plant defence emergence. The gst1, gst11 and peptide methionine sulfoxide reductase genes, which were turned on early, are known to play a role in the detoxification of reactive oxygen species. The accumulation of mRNAs for lox1, a latex allergen and a myrosinase binding protein could be related to a jasmonate dependent pathway, while genes for a class III peroxidase and a caffeoyl-CoA 3-O-methyltransferase, both likely to be involved in cell wall reinforcement, were also upregulated.

Resume Cet essai comparatif multicentrique, ouvert, randomise a eu pour but de comparer l'efficacite et la tolerance du cefixime (CFM : 200 mg, deux fois par jour pendant 8 jours) a celles de l'association amoxicilline-acide clavulanique (AAC : 500 mg, trois fois par jour pendant 8 jours) dans le traitement des surinfections de bronchopathies chroniques chez des patients a risque. Soixante dix medecins generalistes ont ete recrutes pour cet essai, aux cotes de 4 pneumologues hospitaliers. Deux cent quarante cinq patients ont ete inclus dans cet essai, soit 120 dans le groupe CFM et 125 dans le groupe AAC. Cent cinquante et un examens cytobacteriologiques de l'expectoration valides selon les criteres de Murray-Washington ont pu etre obtenus. Pour 48/151 (32 %) prelevements, un inoculum d'au moins 107 UFC/ml etait retrouve, avec au total 42 germes isoles consideres pathogenes : Haemophilus influenzae (24; 57 %), Streptococcus pneumoniae (12; 29 %), Moraxella sp (5; 12 %), Staphylococcus aureus (1; 2 %). L'analyse de l'efficacite clinique realisee en intention de traiter pour le critere principal de jugement (efficacite clinique jugee a la visite de fin de traitement) ne retrouve pas de taux de succes significativement differents entre les groupes avec 111/120 (93 %) succes pour CFM vs 113/124 (91 %) pour AAC (p = 0, 69). Dans le groupe CFM, 2/109 (2 %) patients ont presente une rechute contre 4/111 (4 %) patients dans le groupe AAC (p = 0, 42). La retrocession des symptomes (volume de l'expectoration, purulence, dyspnee) a ete rapportee pour 66/104 (64 %) patients sous CFM et 72/107 (67 %) patients sous AAC. Les delais medians de retrocession des symptomes ont ete de 7 (CFM) et de 8 jours (AAC) (Log rank, p = 0,95). L'analyse de la tolerance a revele que 16/120 (13 %) patients du groupe CFM et 29/124 (23 %) patients du groupe AAC ont presente au moins un evenement intercurrent sur la periode globale de l'essai (p = 0,04). Les taux des patients ayant presente au moins un evenement intercurrent imputable au traitement (relation possible ou probable) etaient de 3 % (4/120) dans le groupe CFM et de 13 % (16/124) dans le groupe AAC (p = 0, 006). La majorite des evenements intercurrents recenses dans le groupe AAC etait d'origine digestive. Un arret premature du traitement pour evenement intercurrent a ete note pour 2 patients du groupe CFM et 5 patients du groupe AAC. En conclusion, le cefixime constitue un traitement efficace dans la prise en charge des surinfections de bronchopathies chroniques. Le meilleur profil de tolerance du cefixime et la commodite de son administration biquotidienne peuvent contribuer a l'observance du traitement.