Lipids as markers of induced resistance in wheat: a biochemical and molecular approach.

Our work aimed at a global investigation of the lipid metabolism during the induction of resistance in wheat (Triticum aestivum) against powdery mildew (Blumeria graminis f.sp. tritici). More specifically, the effect of salicylic acid, known as playing a key role in the activation of defence reactions against pathogens in plants, has been investigated. After salicylic acid infiltration, accumulation of phosphatidic acid was observed that could be due to the phospholipase C pathway since an up-regulation of a phospholipase C-encoding gene expression as well as an accumulation of diacylglycerol were observed. The phosphatidic acid accumulation could also result from the phospholipase D pathway since a reduction of phosphatidylethanolamine content occurred. The response to salicylic acid at the octadecanoid pathway level was also investigated: both a lipoxygenase-encoding gene expression and lipoxygenase enzymatic activity were induced by salicylic acid simultaneously with a decrease of the linolenic acid content. Finally, a lipid transfer protein-encoding gene expression was also up-regulated upon salicylic acid infiltration. These observations indicate that lipid metabolism could be considered as a marker of elicitation in wheat.

Induction of resistance in wheat by bacterial cyclic lipopeptides.

Three families of lipopeptides (LPs), surfactin, iturin (including mycosutilin) and fengycin, produced by the rhizabacterium Bacillus subtilis have received considerable attention for their antimicrobial, cytotoxic, antitumor, immunosuppressant and surfactant properties. Among them, iturins and fengycins generally display a strong in vitro antifungal activity. In addition, surfactins are powerful bio surfactants, and although they don't show any direct fungitoxicity, they exhibit some synergistic effect with the antifungal activity of iturins. The aim of our work is to characterize mycosubtilin, surfactin and fengycin, for their ability to protect wheat against two pathogens, Blumeria graminis f.sp. tritici (Bgt), an obligate parasitic fungus responsible for powdery mildew and Mycosphaerella graminicola (Mg), an hemibiotrophic fungus causing Septoria leaf blotch, two of the most important diseases of this crop. In a first step, we measured the protection efficacy of a preventive treatment with LPs against powdery mildew on wheat leaves. At least 41% and 44% protection levels were obtained when surfactin and mycosubtilin, respectively, were sprayed on wheat leaves at doses corresponding to 4g.ha(-1) in the field. We also tested in vitro the impact of LPs on germination of spores. No direct antifungal effect of LPs was observed on Bgt conidia germination, irrespective of the tested concentrations. However, fengycin strongly decreased the germination of Mg conidia and also considerably delayed its growth. Mycasubtilin completely inhibited conidial germination and therefore also its growth while surfactin did not remarkably affect either germination or growth of this fungus. In a second step, RT-qPCR was used to investigate elicitor and priming effects of surfactin and mycosubtilin on the expression levels of defence-related genes. In non-infectious conditions, both surfactin and mycosubtilin induced the expression of two peroxidase encoding genes (POX2, POX381), however, the expression of LOX (lipoxygenase), AOS (allene oxide synthase) genes involved in the octadecanoid pathway, as well as of the pathogenesis-related genes PR1 was only induced by mycosubtilin. In infectious conditions, only surfactin induced the expression of these genes in response to pBgt, mycosubtilin did not exhibit any priming effect. Depending on the targeted pathogen and on the type of LP, these molecules could exhibit direct antifungal effect and/or defence induction, through either elicitation or potentialisation.

Correlation of cytological and biochemical parameters with resistance and tolerance to Mycosphaerella graminicola in wheat.

This study investigated the infection process of Mycosphaerella graminicola and enzyme activities related to reactive oxygen species (ROS) or oxylipin biosynthesis in four French wheat cultivars with variable resistance to M. graminicola infection. At field level, cultivars Caphorn, Maxyl and Gen11 were susceptible, whereas Capnor showed high levels of quantitative resistance. Moreover, Capnor and Gen11 were tolerant, i.e., their yield was less affected by infection compared to non-tolerant Maxyl and Caphorn. These four cultivars were inoculated under laboratory conditions with the M. graminicola IPO323 reference strain. Cytological and biochemical responses were studied on collected first plantlet leaves and several features discriminated between cultivars. However, resistance and tolerance had no impact on the fungal infection process. Levels of lipoxygenase (LOX), peroxidase (PO) and glutathione-S-transferase (GST) activities were also compared with regard to cultivar resistance or tolerance to M. graminicola. LOX, PO and GST activities did not discriminate resistance and tolerance profiles, although a low level of PO in inoculated and non-inoculated plants could be associated with tolerance. In addition, cell necrosis correlated positively with LOX in non-tolerant cultivars, while mycelia surrounding stomata were positively correlated with PO in the resistant cultivar. GST activity presented correlations between cytological and biochemical parameters only for susceptible cultivars. Stomatal and direct penetration were positively correlated with GST activity in the susceptible non-tolerant cultivars, while these correlations were negative in the tolerant cultivar. When combining cytological and biochemical observations with resistance and tolerance profiles, for each cultivar and at each time point, cultivars could be classified in tight accordance with their previous field characterisation. Moreover, tolerance allowed us to distinguish susceptible cultivars when both biochemical and cytological parameters were considered together.

Induction of resistance in wheat against powdery mildew by bacterial cyclic lipopeptides.

In conventional agricultural practices, fungicides are extensively used to control the development of many fungal plant pathogens. However, the reduction of pesticide applications in the field, which is recommended by authorities and approved by public opinion, may lead to a re-emergence of diseases. Alternative strategies have therefore to be developed in order to control fungal infection; one of them is based on plants natural resistance reinforcement caused by elicitors. Our project aims at characterizing mycosubtilin, surfactin and fengycin, three bacterial cyclic non-ribosomal lipopeptides produced by the rhizobacterium Bacillus subtilis, for their ability to induce resistance in wheat against powdery mildew (Blumeria graminis f.sp. tritici). RT-qPCR approach was used to investigate effect of lipopeptides on expression pattern of defence-related genes, such as PR protein-encoding genes or genes involved in plant defence pathways (reactive oxygen species (ROS) metabolism, lipid peroxidation, phenylpropanoid and octadecanoid pathways) in response to fungus and revealed that expression of LOX and PR1 was strongly induced by surfactin at 24h and 18h after inoculation, respectively. Mycosubtilin seemed to be more efficace to induce expression of OXO and Ltp. Surfactin could also induce expression of chitinase encoding genes but neither surfactin nor mycosubtilin could induce the expression of GSTphi and PAL genes in response to the fungus.

In vitro activity of new antimicrobial agents against glycopeptide-resistant Enterococcus faecium clinical isolates from France between 2006 and 2008.

OBJECTIVE: The aim of this study was to determine the in vitro activity of six new antimicrobial agents against glycopeptide-resistant enterococci (GRE) strains from France. METHODS: Sixty epidemiologically unrelated clinical isolates of Enterococcus faecium (vanA or vanB), received at the National Reference Centre for Enterococci (CNR-Enc) between 2006 and 2008, were studied. The MICs of the following antibiotics were determined by broth microdilution according to Antibiogram Committee of the French Society for Microbiology (CA-SFM) guidelines: quinupristin-dalfopristin (Q-D), linezolid (LZD), daptomycin (DPT), tigecycline (TGC), ceftobiprole (CFT), and telavancin (TLV). Strains were classified using clinical breakpoints recommended by the CA-SFM (Q-D, LZD, TGC), or the Clinical and Laboratory Standards Institute (DPT). RESULTS: All strains were susceptible to LZD and DPT (MIC(90), 4 and 2µg/ml, respectively) and only a single strain presented intermediate susceptibility to tigecycline (MIC(90), 0.25µg/ml). Thirty percent of strains were resistant to Q-D (MIC(90), 4µg/ml), and CFT was constantly inactive (MIC(90), 64µg/ml). Finally, TLV showed low-level MICs (MIC(90), 0.5µg/ml) against vanB-positive isolates but not against vanA-positive isolates (MIC(90), 8µg/ml). CONCLUSION: Although several antibiotics are still active against GRE, it is essential to maintain an active antimicrobial resistance surveillance for these microorganisms considered as a model of multidrug resistance with a potential to transfer resistance to other bacterial species (e.g. Staphylococcus aureus).

Mechanisms of resistance and tolerance to Mycosphaerella graminicola in wheat.

The aim of this study was to investigate the infection process of M. graminicola and the defence mechanisms related to active oxygen species (AOS) in five French wheat cultivars. These cultivars exhibited various resistant levels to M. graminicola infection: Maxyl, Caphorn and Gen11 are susceptible cultivars, whereas Capnor and Gen23 show high levels of quantitative resistances. In addition, Capnor, Gen23 and Gen11 are tolerant cultivars, i.e., their yield performance was less affected by infection compared to non-tolerant cultivars. Cultivars were inoculated with the IPO323 reference M. graminicola strain. First wheat leaves were collected 3, 5, 7, 9, 11, 13, 15, 17, 19, and 21 days after inoculation. The cytological and antioxidant response of the cultivars were both studied over the whole time course. Although infection occurred mainly through stomata, direct penetration attempts were also scored. Moreover, papilla formation turned out to be very rare. Assays for changes in peroxydase (PO), glutathione-S-transferase (GST) and lipoxygenase (LOX) activities allowed us to compare their levels in the five French wheat cultivars regarding to their resistance and/or tolerance towards M. graminicola infection. PO and GST were correlated to necrosis probably as a consequence of detoxification and LOX was related to some of the germination process steps. We also showed that significant differences for several biochemical parameters exist between the studied cultivars in non inoculated conditions but these differences were less important in the presence of the fungus.

[Emergence of vancomycin-dependent enterococci following glycopeptide therapy: case report and review]. / Emergence d'entérocoque dépendant de la vancomycine à la suite d'un traitement par glycopeptide: cas clinique et revue.

INTRODUCTION: Outbreaks of vancomycin-resistant enterococci have been increasingly reported in France over the last three years. We report here, the emergence of a vancomycin-dependent enterococci isolate following glycopeptide therapy. PATIENTS AND METHODS: An Enterococcus faecium isolate that required vancomycin for growth was cultured from the stools of a liver transplant recipient who was colonised with vancomycin-resistant enterococci and who received vancomycin treatment for methicillin-resistant Staphylococcus aureus infection. The resistant isolate and the dependent isolate were typed by pulsed-field gel electrophoresis. The sequence of the ddl gene coding for the D-Ala: D-Ala ligase was analysed. RESULTS: The dependent isolate was primary cultured onto a vancomycin-containing screening medium and could not be subcultured in the absence of vancomycin. Both the resistant and dependent isolates harboured the vanA gene and they had the same DNA restriction pattern after pulsed-field gel electrophoresis. Dependence on vancomycin was associated with a 1-bp deletion in the D-Ala: D-Ala ligase gene leading to an early stop odon. CONCLUSION: Cultures onto vancomycin-containing media are warranted for clinical specimens from patients, who are known to carry vancomycin-resistant enterococci and receive vancomycin therapy.

Extraversion and the rebound effect after thought suppression.

83 participants thought about a white bear before or after trying to suppress the idea. There was no rebound effect (more expression of white-bear thoughts after than before suppression) for either introverts or extraverts.

Facial nerve: vascular-related anatomy at the stylomastoid foramen.

We dissected 30 facial nerves in fresh cadavers after arterial casting with red latex to provide specific information about the arterial-related anatomy of the trunk of the facial nerve from the stylomastoid foramen to its bifurcation. We found that a wide anatomic variability does exist. The trunk of the facial nerve was in proximity to the stylomastoid artery, which originated from the posterior auricular artery in 70% of the specimens (21/30), from the occipital artery in 20% (6/30), and directly from the external carotid artery in 10% (3/30). The stylomastoid artery passed medially to the trunk of the facial nerve in 63 of the specimens (19/30) and laterally in 37% (11/30). Among these 11 specimens, 8 were large-caliber stylomastoid arteries. During parotid surgery, the main trunk of the facial nerve may be difficult to identify, because a large-caliber stylomastoid artery can mask it. Therefore, it is important to dissect this artery with caution.

[Head and neck desmoid tumor in children: a case report and review of the literature]. / Tumeur desmoïde cervico-faciale de l'enfant. A propos d'un cas et revue de la littérature.

We report a case of desmoid tumor in the submandibular region in an 18-month-old girl. Head and neck desmoid tumors are uncommon in children and diagnosis is a difficult task because the tumors are often classified as different types of fibromatosis. This histologically benign affection is characterized by local expansion or destruction and tends to recur. Pathology gives the positive diagnosis, showing fibroblastic monoclonal proliferation between the cellular center and the collagen periphery. Electron microscopy evidences an abundant collagen network enclosing a polymorphous cellular proliferation. Immunohistochemistry defines vimentin and actin positive desmoid tumors. Surgery is usually the therapeutic choice. Chemotherapy and radiotherapy may be used in conjunction with surgery in situations of recurrence or unsatisfactory surgical margin. There is a risk of recurrence which can be detected with regular follow-up examinations.

Alagille syndrome with cavernous carotid artery aneurysm.

We present a case of right sided blindness caused by a cavernous carotid artery aneurysm in a 17-year-old patient presenting with an Alagille syndrome. The diagnosis was made by magnetic resonance imaging and confirmed by angiography. This aneurysm was treated successfully with endovascular placement of detachable balloons. Cerebral vascular malformations are rarely reported in association with this syndrome. We discuss the clinical presentation, diagnosis, treatment and detection of this type of abnormality.

[Temporal fibrous dysplasia with labyrinthine involvement. Apropos of a case and review of the literature]. / Dysplasie fibreuse temporale avec atteinte labyrinthique. A propos d'un cas et revue de la littérature.

Craniofacial fibrous dysplasia manifests clinically with dysmorphic syndrome, ophtalmologic or otologic signs. We report a case of temporal polyostotic fibrous dysplasia with vertigo and sensorineural hearing loss. Sensorineural hearing loss, with no cholesteatoma associated, as described in our case is rarely described. We review the literature concerning main clinical, diagnostic and therapeutic aspects of this disease.

[A case of Kikuchi disease. Review of the literature]. / A propos d'un cas de maladie de Kikuchi. Revue de la littérature.

We report a case of Kikuchi's disease in a young man. It is a rare entity, described for the first time in 1972. It manifests clinically with cervical adenopathy and fever, often associated with other non-specific clinical signs. Laboratory tests are often normal. The diagnosis is established on the basis of histologic of lymph node excisional biopsy. Kikuchi's disease is likely to be misinterpreted as malignant lymphoma or systemic lupus erythematosus. It generally needs no treatment because it runs a spontaneously benign course with complete resolution of the symptoms within 6 months. Secondary systemic lupus erythematosus may develop. For this reason, regular follow-up of patients is recommended. The etiopathogenesis of this disease is still unknown, perhaps due to an immunologic phenomenon. It could be a hyperimmune reaction induced by various antigenic agents (infectious, neoplasic), or an autoimmune process.