An experimental system to study responses of Medicago truncatula roots to chitin oligomers of high degree of polymerization and other microbial elicitors.

KEY MESSAGE: A fully acetylated, soluble CO preparation of mean DP of ca. 7 was perceived with high sensitivity by M. truncatula in a newly designed versatile root elicitation assay. The root system of legume plants interacts with a large variety of microorganisms, either pathogenic or symbiotic. Understanding how legumes recognize and respond specifically to pathogen-associated or symbiotic signals requires the development of standardized bioassays using well-defined preparations of the corresponding signals. Here we describe the preparation of chitin oligosaccharide (CO) fractions from commercial chitin and their characterization by a combination of liquid-state and solid-state nuclear magnetic resonance spectroscopy. We show that the CO fraction with highest degree of polymerization (DP) became essentially insoluble after lyophilization. However, a fully soluble, fully acetylated fraction with a mean DP of ca. 7 was recovered and validated by showing its CERK1-dependent activity in Arabidopsis thaliana. In parallel, we developed a versatile root elicitation bioassay in the model legume Medicago truncatula, using a hydroponic culture system and the Phytophthora ß-glucan elicitor as a control elicitor. We then showed that M. truncatula responded with high sensitivity to the CO elicitor, which caused the production of extracellular reactive oxygen species and the transient induction of a variety of defense-associated genes. In addition, the bioassay allowed detection of elicitor activity in culture filtrates of the oomycete Aphanomyces euteiches, opening the way to the analysis of recognition of this important legume root pathogen by M. truncatula.

[Optimization of a haematopoietic stem cell freezing process using a qualification protocol applicable to a programmable freezer]. / Optimisation d'un processus de congélation des cellules souches hématopoïétique par l'application d'un protocole de qualification d'un congélateur programmable.

BACKGROUND: The freezing phase is a critical step of the freezing process of the hematopoietic stem cells. To standardize the decrease of the temperature, the use of a programmable freezer is recommended. There is no available protocol, neither to describe exactly the validation of a programmable freezer, nor to prove the performance of the freezing/thawing step of the grafts. METHOD: We describe a validation protocol with three phases: first a qualification of installation, then an operational qualification and finally, a qualification of performance. The validation is performed in tandem between the freezer which is routinely used (Nicool Plus) and a new one (Freezal). RESULTS: With this protocol, we demonstrate the efficacy of the freezing program and its ability to assure the quality of the grafts reinjected to the patients, particularly in terms of cellular efficiency on CD34+ hematopoietic stem cells. On these cells, we measured a significant increase of cellular efficiency (+10%) after freezing with the Freezal. CONCLUSION: Here, we propose a validation protocol which is able to qualify a programmable freezer. This protocol can optimize the capability of the freezer and is able to prove its performance.

Gustatory sensilla sensitive to protein kairomones trigger host acceptance by an endoparasitoid.

Proteins isolated from the host cocoon of Acrolepiopsis assectella (Lepidoptera: Yponomeutoidea) act as kairomones for host acceptance by the endoparasitoid wasp Diadromus pulchellus Wesmael (Hymenoptera: Ichneumonidae). In this study, morphological, ultrastructural and electrophysiological studies were carried out in order to identify the contact chemoreceptive sensilla on the parasitoid antennae that perceive the protein kairomones. Three types of sensillum on the antennae of the females were found to have a chemosensory function. The receptor cell(s) of one sensillar type were shown to give a positive electrophysiological response to protein kairomones. This sensillar type is apically multiporous and female specific. Consequently, this sensillum could be the one implicated in the perception of the protein kairomone that triggers the host-acceptance behaviour of D. pulchellus females.

An energetic correlation of ab initio and NMR studies of the 3'-gauche effect in 3'-substituted thymidines.

A straightforward correlation of our experimental NMR findings on 3'-substituted thymidine derivatives with that of the ab initio calculations shows that (i) the delta Go298kNRM of N reversible S equilibrium in nucleoside can be predicted from the ab initio calculated delta ES-N obtained from 6-311++G** level of theory; (ii) the substituent-dependent steric and stereoelectronic effects on the bias of the two-state N reversible S equilibrium in nucleosides can also be predicted from the ab initio calculations with sufficiently large basis functions, and (iii) the necessity of mimicking the solvation behaviour of the experimental NMR measurement condition in the ab initio calculations of biomolecules is also emphasized.

The Transmission of the Electronic Character of Guanin-9-yl Drives the Sugar-Phosphate Backbone Torsions in Guanosine 3',5'-Bisphosphate.

The intrinsic flexibility of the pentoses in RNA allows dynamic transmission of information on the electronic character of the nucleobase to modulate the sugar conformation by an interplay of gauche and anomeric effects. This modulation in turn steers the phosphate backbone conformation by tuning the 3'-O-P-O(ester) anomeric effect, as shown by conformational analysis of EtpGpMe as a function of pD. This tunable transmission is stereoelectronic in nature, and operates by appropriate overlap between donor and acceptor orbitals (see scheme), which causes single-stranded RNA to behave as a molecular wire.

Fast onset: an open study of the treatment of major depressive disorder with nefazodone and pindolol combination therapy.

Pindolol, a beta-adrenergic and presynaptic 5-HT1 vA antagonist, when added to specific serotonin reuptake inhibitors, potentiates the antidepressant action, leading to an earlier onset of effect. Following on from the suggestion that nefazodone, a specific serotonin reuptake inhibitor and antagonist of 5-HT2, improves 5-HT1A-mediated transmission, we used a pindolol and nefazodone combination treatment for major depressive disorder. Twenty outpatients underwent a 4-week trial. Patients were seen twice a week, and completed efficacy and safety measures including the 17-item Hamilton Depression Scale, the Montgomery-Asberg Depression Rating Scale and the Clinical Global Impression scales. Results demonstrated significant improvement in all efficacy measures after one visit (2-4 days of treatment), with decreasing depression scores on all measures continuing throughout the trial. After 1 week of treatment, 15 out of 20 patients had experienced a 50% or greater reduction in their 17-item Hamilton Depression Scale scores. Remission rates were dramatic, with 40% of patients in remission after 1 week of treatment and 90% after 4 weeks. This open study of nefazodone-pindolol combination therapy suggests that this may be a new treatment option for patients with major depressive disorder; however, it needs to be replicated in a double-blind trial before conclusions regarding efficacy and safety can be made.

A double-blind placebo-controlled trial comparing fluvoxamine and imipramine in the treatment of panic disorder with or without agoraphobia.

This study compared the efficacy, tolerability, and safety of fluvoxamine, imipramine, and placebo in the treatment of panic disorder with or without agoraphobia. Fifty-four outpatients participated in the randomized, double-blind trial as part of a multicenter trial. After meeting inclusion criteria and completing screening requirements (e.g., laboratory testing, electrocardiogram, physical examination), patients were entered in a single-blind placebo washout phase. They were then randomized to either fluvoxamine, imipramine, or placebo. Measurements completed at each visit included the number and severity of panic attacks per week, the Sheehan Panic and Anticipatory Anxiety Scale, and the Clinical Global Impressions, and others. Results show that fluvoxamine is more effective than placebo and as effective as imipramine in reducing spontaneous panic attacks in moderate to severe panic disorder. However, starting doses of fluvoxamine and imipramine should be low to minimize untoward side effects (such as insomnia and agitation) and maintain compliance.