Paraburkholderia phytofirmans PsJN-Plants Interaction: From Perception to the Induced Mechanisms.

The use of plant-associated bacteria has received many scientific and economic attention as an effective and alternative method to reduce the chemical pesticides use in agriculture. The genus Burkholderia includes at least 90 species including pathogenic strains, plant pathogens, as well as plant beneficial species as those related to Paraburkholderia, which has been reported to be associated with plants and exerts a positive effect on plant growth and fitness. Paraburkholderia phytofirmans PsJN, a beneficial endophyte able to colonize a wide range of plants, is an established model for plant-associated endophytic bacteria. Indeed, in addition to its plant growth promoting ability, it can also induce plant resistance against biotic as well as abiotic stresses. Here, we summarized an inventory of knowledge on PsJN-plant interaction, from the perception to the resistance mechanisms induced in the plant by a way of the atypical colonization mode of this endophyte. We also have carried out an extensive genome analysis to identify all gene clusters which contribute to the adaptive mechanisms under different environments and partly explaining the high ecological competence of P. phytofirmans PsJN.

Osmotic Stress and ABA Affect Immune Response and Susceptibility of Grapevine Berries to Gray Mold by Priming Polyamine Accumulation.

Abiotic factors inducing osmotic stress can affect plant immunity and resistance against pathogen attack. Although a number of studies have characterized grapevine responses to various forms of biotic and abiotic stresses, the relationships between osmotic stress response and susceptibility of mature berries to Botrytis cinerea still remain unknown. In this study, we investigated the effects of osmotic stress and abscisic acid (ABA) on defense responses of mature grapevine berries before and after B. cinerea infection. We focused on the possible involvement of polyamines in the interaction between osmotic stress response and susceptibility to B. cinerea. We showed that osmotic stress induced by PEG or sucrose, and exogenous ABA induce transient but low defense responses, including weak expression of PR genes and phytoalexin synthesis in mature berries. This was accompanied by an upregulation of NCED2 involved in ABA biosynthesis and a large production of free polyamines. However, osmotic stress followed by B. cinerea infection primed berries for enhanced accumulation of polyamines, but slowed down the defense responses and increased susceptibility to the pathogen. A weak increase of diamine- and polyamine-oxidase activities was also recorded in stressed berries, but declined after pathogen infection. The pretreatment of stressed berries with appropriate inhibitors of diamine- and polyamine-oxidases further increased polyamine level and greatly lowered defense responses, leading to higher susceptibility to B. cinerea. These results suggest that increased polyamine titer through low activation of their oxidative degradation in grape berries may contribute at least in part to the weakening of defense responses and subsequent disease susceptibility.

Burkholderia phytofirmans PsJN Confers Grapevine Resistance against Botrytis cinerea via a Direct Antimicrobial Effect Combined with a Better Resource Mobilization.

Plant innate immunity serves as a surveillance system by providing the first line of powerful weapons to fight against pathogen attacks. Beneficial microorganisms and Microbial-Associated Molecular Patterns might act as signals to trigger this immunity. Burkholderia phytofirmans PsJN, a highly efficient plant beneficial endophytic bacterium, promotes growth in a wide variety of plants including grapevine. Further, the bacterium induces plant resistance against abiotic and biotic stresses. However, no study has deciphered triggered-mechanisms during the tripartite interaction between grapevine, B. phytofirmans PsJN and Botrytis cinerea. Herein, we showed that in contrast with classical rhizobacteria, which are restricted in the root system and act through ISR, B. phytofirmans PsJN is able to migrate until aerial part and forms at leaves surface a biofilm around B. cinerea mycelium to restrict the pathogen. Nevertheless, considering the endophytic level of PsJN in leaves, the plant protection efficacy of B. phytofirmans PsJN could not be explained solely by its direct antifungal effect. Deeper investigations showed a callose deposition, H2O2 production and primed expression of PR1, PR2, PR5, and JAZ only in bacterized-plantlets after pathogen challenge. The presence of PsJN modulated changes in leaf carbohydrate metabolism including gene expression, sugar levels, and chlorophyll fluorescence imaging after Botrytis challenge. Our findings indicated that protection induced by B. phytofirmans PsJN was multifaceted and relied on a direct antifungal effect, priming of defense mechanisms as well as the mobilization of carbon sources in grapevine leaf tissues.

Incidence and Clinical Features of Bleeding Peptic Ulcers in Acute Upper Gastrointestinal Bleeding: -Experience of Moroccan University Hospital Unit

Introduction: Peptic ulcer disease (PUD) has been recognized as the leading cause of acute upper gastrointestinal bleeding (AUGIB). This study aims to report general features of bleeding peptic ulcers in patients who benefit of urgent endoscopy in our department after an acute upper gastrointestinal hemorrhage. Results: A total of 1809 patients were explored for acute upper gastrointestinal bleeding in our unit since 2003 to 2008. Gastroduodenal peptic ulcers were the most frequent diagnosed etiology. They present 38% of all reported causes of bleeding (n=527) (table I). 25% were located at duodenal mucosa (n= 347) and 13% were gastric ulcers (n=180). No esophageal ulcers were reported. Incidence of both duodenal and gastric ulcers decreases during the last years. Conclusion: In our department; incidence of bleeding peptic ulcer disease is decreasing but they continue to be the first cause of AUGIB

Burkholderia phytofirmans PsJN reduces impact of freezing temperatures on photosynthesis in Arabidopsis thaliana.

Several plant growth-promoting rhizobacteria (PGPR) are known to improve plant tolerance to multiple stresses, including low temperatures. However, mechanisms underlying this protection are still poorly understood. The aim of this study was to evaluate the role of the endophytic PGPR, Burkholderia phytofirmans strain PsJN (Bp PsJN), on Arabidopsis thaliana cold tolerance using photosynthesis parameters as physiological markers. Under standard conditions, our results indicated that Bp PsJN inoculation led to growth promotion of Arabidopsis plants without significant modification on photosynthesis parameters and chloroplast organization. However, bacterial colonization induced a cell wall strengthening in the mesophyll. Impact of inoculation modes (either on seeds or by soil irrigation) and their effects overnight at 0, -1, or -3°C, were investigated by following photosystem II (PSII) activity and gas exchanges. Following low temperatures stress, a decrease of photosynthesis parameters was observed. In addition, during three consecutive nights or days at -1°C, PSII activity was monitored. Pigment contents, RuBisCO protein abundance, expression of several genes including RbcS, RbcL, CBF1, CBF2, CBF3, ICE1, COR15a, and COR78 were evaluated at the end of exposure. To assess the impact of the bacteria on cell ultrastructure under low temperatures, microscopic observations were achieved. Results indicated that freezing treatment induced significant changes in PSII activity as early as the first cold day, whereas the same impact on PSII activity was observed only during the third cold night. The significant effects conferred by PsJN were differential accumulation of pigments, and reduced expression of RbcL and COR78. Microscopical observations showed an alteration/disorganization in A. thaliana leaf mesophyll cells independently of the freezing treatments. The presence of bacteria during the three successive nights or days did not significantly improved A. thaliana responses but prevented the plasmalemma disruption under freezing stress.

Acute upper gastro-intestinal bleeding in morocco: what have changed?

Objective. In the present study, we aimed to investigate epidemiological, clinical, and etiological characteristics of acute upper gastro-intestinal bleeding. Materials and Methods. This retrospective study was conducted between January 2003 and December 2008. It concerned all cases of acute upper gastroduodenal bleeding benefited from an urgent gastro-intestinal endoscopy in our department in Morocco. Characteristics of patients were evaluated in terms of age, gender, medical history, presenting symptoms, results of rectal and clinical examinations, and endoscopy findings. Results. 1389 cases were registered. As 66% of the patients were male, 34% were female. Mean age was 49. 12% of patients had a history of previous hemorrhage, and 26% had a history of NSAID and aspirin use. Endoscopy was performed in 96%. The gastroduodenal ulcer was the main etiology in 38%, followed by gastritis and duodenitis in 32.5%. Conclusion. AUGIB is still a frequent pathology, threatening patients' life. NSAID and aspirin are still the major risk factors. Their impact due to peptic ulcer remains stable in our country.

[Massive rectorrhagia and acute intestinal occlusion revealing Peutz-Jeghers syndrome: apropos of 3 cases]. / Rectorragie massive et occlusion intestinale aigueë révélant un syndrome de Peutz-Jeghers: à propos de trois cas.

Peutz-Jeghers syndrome is a rare hereditary disorder involving digestive polyposis with hamartomatous gastrointestinal polyps and mucocutaneous lentiginosis. We report three cases in which this syndrome was detected by complications: a massive rectal hemorrhage requiring a blood transfusion in one case and acute impaction of the bowel requiring emergency surgery in the other two. This work demonstrates the importance of the complications that may indicate that the patient has this syndrome. We also discuss the cancers of the digestive system and other organs that may be associated with PJS and recent progress in genetic research into this disease.

Recognition of seed varieties using a temporal organisation map analysis of electrophoretic images.

This paper presents a method for seed varieties recognition using one-dimensional electrophoresis gels. It employs a neural network basically constituted of temporal organisation maps (TOM). The TOM model is a neural net which was initially developed for speech recognition. It can be trained to recognise words in speech by reference to the sound pattern over a sequence of time steps. Electrophoresis creates a set of bands in the gel, caused by migration of protein from the seed. Each seed variety generates a characteristic pattern. The bands are made visible by staining. They can then be imaged and digitised to create an input to a TOM, which treats the variation with distance along the lane in the same way as the time sequence for which it was originally employed. In this way the characteristic signature of a seed variety can be recognised. A set of 50 images--each containing 10 to 15 lanes--was used to train and test the performance of a neural network in recognising 75 cereal varieties. The network could achieve a recognition rate of 98%, provided that the gel was not distorted or cracked during heating or drying. Details of the design and training of the network are given.

[The pseudo-tumoral form of hepatic tuberculosis. Five case reports]. / La forme pseudo-tumorale de la tuberculose hépatique. A propos de cinq cas.

The authors report 5 cases of pseudotumoral tuberculosis of the liver. They essentially involved young men from disadvantaged socio-economic backgrounds. Clinically, poor general condition with massive weight loss was constant, while pyrexia and hepatomegaly were sometimes absent. Hepatobiliary ultrasonography revealed hypoechogenic or even anechogenic lesions between 1.5 and 3.5 cm in diameter. Diagnostic confirmation was histological after needle biopsy. The outcome after antibiotic treatment with or without drainage, was recovery, with ultrasonographic normalization of the liver, in all patients, with a mean follow-up of 22 months.

[Epidemiologic profile of colorectal cancers in a medical service at Rabat]. / Profil épidémiologique des cancers colo-rectaux dans un service de médecine à Rabat.

The authors report their clinical experience concerning carcinomas of the colon and rectum based upon 212 patients hospitalised in a Department of Medicine. The group consisted of 109 men and 101 women. The mean age was 46.4. Almost 50 per cent of the patients had first presented only 6 months after the onset of symptoms. The recto-sigmoid was the commonest site (81.6 per cent). From a histological standpoint, adenocarcinomas were commonest (93.86 per cent of carcinomas).