Evaluation of rice genotypes resistance to bacterial leaf blight in Togo

The present study aimed to evaluate rice genotypes for resistance to bacterial leaf blight caused by Xanthomonas oryzae pv. oryzae. Twenty-one genotypes including six genotypes grown in Togo, two improved genotypes from Africa Rice and thirteen isogenic lines from IRRI were tested. The results revealed differential reactions of genotypes in the expression of the disease. Additive main effect and multiplicative interaction analysis allowed identifying three groups of genotypes according to the level of the disease expression: resistant group made up of the genotype IR24 and all the twelve near isogenic lines tested except the line IRBB5, medium resistant group made up of three genotypes grown in Togo (NERICA4, NERICA8 and NERICA14), the genotype Giganté from AfricaRice, and susceptible group including five genotypes fromITRA (TGR203 and IR841), from AfricaRice (NERICA19 and TOG5681) and the near isogenic line IRBB5 from IRRI. The results provided useful information indicating that none of the grown varieties tested was resistant to BLB, thus revealing a potential risk of epidemics since these genotypes were only medium resistant to susceptible. However, experiments under field conditions in different environments of Togo are needed.© 2012 International Formulae Group. All rights reserved

Regulation status of quarantine pests of rice seeds in the Economic Community of West African States (ECOWAS)

Open Access JournalThe ever growing international trade has limited efforts towards the prevention of introduction, spread and establishment of invasive organisms. Non-native pests can cause severe loss of production and lead to restriction in exchange of genetic materials and seed marketing across regions. Regulating pests’ movement through quarantine measures and establishment of regional boards has been identified as a way to deal with introduction and expansion of invasive organisms. This review analyzes the different pest regulations in the West African sub-region with a specific focus on the implementation of quarantine measures in rice as a case study. The various regulations related to seed production, certification and marketing, and quarantine regulations in West Africa were analyzed and their enforcement and performance were assessed through comparison to international standards, especially the International Plant Protection Convention (IPPC). Although a regional regulation on seeds and phytosanitary measures has been elaborated, ECOWAS countries are still enforcing their national phytosanitary legislations, which are nearly the same in all West African countries - they all aim at ensuring plant health by applying preventive and curative measures to prevent the introduction and spread of pests in their territory by controlling the import and export of plant materials and disseminating appropriate pest management techniques to boost agricultural production. Most ECOWAS countries are yet to submit their phytosanitary legislation to IPPC to comply with Article VII.2i of the endorsed convention. In addition, the entry points are not well defined and provided to the IPPC according to the Article VII.2d of the convention. When the quarantine list is available, the organisms regulated for each crop species are not stated, posing a real problem not only for rice genetic resource exchanges for research purposes but also for rice seed trade. Efforts and resources should be devoted by each country to research on pests and regulatory mechanisms in order to define, among others, pest status in the region, and to update regularly the quarantine pests list in the West African region

Diversity of the Rice Blast Pathogen Populations in Ghana and Strategies for Resistance Management

The present study describes the outputs of a collaborative research programme funded by the UK`s Department for International Development-Crop Protection Program to investigate the genetic (lineages) and pathogenic (pathotypes) diversity of the blast fungus populations and characterize the key sites suitable for resistance screening. Seventy-one Magnaporthe grisae isolates were collected from seven regions where rice is grown, representing blast populations in Ghana. Following molecular characterization, these isolates were grouped into four distinct lineages designated as GH-1, GH-2, GH-3 and GH-4 and 25 pathotypes. GH-1 was the major lineage comprising 52% of all the isolates and was present across the country on up to 24 rice cultivars. GH-2 comprising of 30% of the isolates sampled was restricted in distribution mainly from Hohoe area on up to seven cultivars. GH-3 consisted of six isolates from Western, Eastern and Central Regions while GH-4 consisted of two isolates from Nyankpala in Northern Region. Occurrence of blast pathogen on wild rice and weed hosts has been observed and their potential impact needs to be considered in blast/weed management. Baseline data new to Ghana on the diversity and distribution pattern of the blast pathogen populations have been established and key sites identified. Adaptive research is continuing to develop technologies suitable for long-term pathogen monitoring, identify sources of resistance and develop appropriate blast management strategies

Endoplasmic reticulum-plasma membrane contact sites integrate sterol and phospholipid regulation

Tether proteins attach the endoplasmic reticulum (ER) to other cellular membranes, thereby creating contact sites that are proposed to form platforms for regulating lipid homeostasis and facilitating non-vesicular lipid exchange. Sterols are synthesized in the ER and transported by non-vesicular mechanisms to the plasma membrane (PM), where they represent almost half of all PM lipids and contribute critically to the barrier function of the PM. To determine whether contact sites are important for both sterol exchange between the ER and PM and intermembrane regulation of lipid metabolism, we generated Δ-super-tether (Δ-s-tether) yeast cells that lack six previously identified tethering proteins (yeast extended synatotagmin [E-Syt], vesicle-associated membrane protein [VAMP]-associated protein [VAP], and TMEM16-anoctamin homologues) as well as the presumptive tether Ice2. Despite the lack of ER-PM contacts in these cells, ER-PM sterol exchange is robust, indicating that the sterol transport machinery is either absent from or not uniquely located at contact sites. Unexpectedly, we found that the transport of exogenously supplied sterol to the ER occurs more slowly in Δ-s-tether cells than in wild-type (WT) cells. We pinpointed this defect to changes in sterol organization and transbilayer movement within the PM bilayer caused by phospholipid dysregulation, evinced by changes in the abundance and organization of PM lipids. Indeed, deletion of either OSH4, which encodes a sterol/phosphatidylinositol-4-phosphate (PI4P) exchange protein, or SAC1, which encodes a PI4P phosphatase, caused synthetic lethality in Δ-s-tether cells due to disruptions in redundant PI4P and phospholipid regulatory pathways. The growth defect of Δ-s-tether cells was rescued with an artificial "ER-PM staple," a tether assembled from unrelated non-yeast protein domains, indicating that endogenous tether proteins have nonspecific bridging functions. Finally, we discovered that sterols play a role in regulating ER-PM contact site formation. In sterol-depleted cells, levels of the yeast E-Syt tether Tcb3 were induced and ER-PM contact increased dramatically. These results support a model in which ER-PM contact sites provide a nexus for coordinating the complex interrelationship between sterols, sphingolipids, and phospholipids that maintain PM composition and integrity

Serum Deprivation of Mesenchymal Stem Cells Improves Exosome Activity and Alters Lipid and Protein Composition

Exosomes can serve as delivery vehicles for advanced therapeutics. The components necessary and sufficient to support exosomal delivery have not been established. Here we connect biochemical composition and activity of exosomes to optimize exosome-mediated delivery of small interfering RNAs (siRNAs). This information is used to create effective artificial exosomes. We show that serum-deprived mesenchymal stem cells produce exosomes up to 22-fold more effective at delivering siRNAs to neurons than exosomes derived from control cells. Proteinase treatment of exosomes stops siRNA transfer, indicating that surface proteins on exosomes are involved in trafficking. Proteomic and lipidomic analyses show that exosomes derived in serum-deprived conditions are enriched in six protein pathways and one lipid class, dilysocardiolipin. Inspired by these findings, we engineer an artificial exosome, in which the incorporation of one lipid (dilysocardiolipin) and three proteins (Rab7, Desmoplakin, and AHSG) into conventional neutral liposomes produces vesicles that mimic cargo delivering activity of natural exosomes

Randomized comparison of amodiaquine plus sulfadoxine-pyrimethamine, artemether-lumefantrine, and dihydroartemisinin-piperaquine for the treatment of uncomplicated Plasmodium falciparum malaria in Burkina Faso.

BACKGROUND: Combination antimalarial therapy is advocated to improve treatment efficacy and limit selection of drug-resistant parasites. We compared the efficacies of 3 combination regimens in Bobo-Dioulasso, Burkina Faso: amodiaquine plus sulfadoxine-pyrimethamine, which was recently shown to be highly efficacious at this site; artemether-lumefantrine, the new national first-line antimalarial regimen; and dihydroartemisinin-piperaquine (DP), a newer regimen. METHODS: We enrolled 559 patients >or=6 months of age with uncomplicated Plasmodium falciparum malaria and randomized them to the 3 regimens. We analyzed the risk of recurrent parasitemia by day 28 and day 42, both unadjusted and adjusted by PCR methods to distinguish recrudescence and new infection. RESULTS: Complete data were available for 517 (92.5%) of the enrolled subjects. Early treatment failures occurred in 5 patients treated with amodiaquine plus sulfadoxine-pyrimethamine and in 2 patients each treated with the other regimens. The day 28 risk of recurrent parasitemia, unadjusted by genotyping, was significantly higher for patients receiving artemether-lumefantrine than for patients receiving amodiaquine plus sulfadoxine-pyrimethamine (20.1% vs. 6.2%; risk difference, 13.8%; 95% confidence interval, 7.0%-20.7%) or dihydroartemisinin-piperaquine (20.1% vs. 2.2%; risk difference, 17.9%; 95% confidence interval, 11.6%-24.1%). Similar differences were seen for children <5 years of age (54% of the study population) and when outcomes were extended to 42 days. Significant differences were not seen between outcomes for patients receiving amodiaquine plus sulfadoxine-pyrimethamine and outcomes for those receiving dihydroartemisinin-piperaquine. Recrudescences were uncommon (occurring in <5% of patients) in all treatment groups. No serious adverse events were noted. CONCLUSIONS: All regimens were highly efficacious in clearing infection, but considering the risks of recurrent malaria after therapy, the amodiaquine plus sulfadoxine-pyrimethamine and dihydroartemisinin-piperaquine regimens were more efficacious than the artemether-lumefantrine regimen (the new national regimen in Burkina Faso) for the treatment of uncomplicated P. falciparum malaria

Control of mechanical pain hypersensitivity in mice through ligand-targeted photoablation of TrkB-positive sensory neurons

Mechanical allodynia is a major symptom of neuropathic pain whereby innocuous touch evokes severe pain. Here we identify a population of peripheral sensory neurons expressing TrkB that are both necessary and sufficient for producing pain from light touch after nerve injury in mice. Mice in which TrkB-Cre-expressing neurons are ablated are less sensitive to the lightest touch under basal conditions, and fail to develop mechanical allodynia in a model of neuropathic pain. Moreover, selective optogenetic activation of these neurons after nerve injury evokes marked nociceptive behavior. Using a phototherapeutic approach based upon BDNF, the ligand for TrkB, we perform molecule-guided laser ablation of these neurons and achieve long-term retraction of TrkB-positive neurons from the skin and pronounced reversal of mechanical allodynia across multiple types of neuropathic pain. Thus we identify the peripheral neurons which transmit pain from light touch and uncover a novel pharmacological strategy for its treatment

Derivation of Systolic Convolution Arrays

We show how the refinement calculus, combined with the action system formalism gives a stepwise refinement method for deriving parallel convolution algorithms that model systolic computation. We inspect how different architectural designs influence the derivation process. The action systems framework allows us to reuse the derivation to a large extent. We start from the definition of convolution and give an initial action system. Through a series of refinement steps we derive a parallel version of this system. The other designs are derived by merely reorganizing the variables of the system. Every transformation step is verified within the refinement calculus. 1 Introduction The paper presents an outline of a method for formal derivations of parallel convolution. The work has been carried out within the refinement calculus and the action system framework. An action system is a parallel or distributed program where parallel activity is described in terms of events, so called actions. Se..

Screening of rice varieties for resistance to bacterial leaf blight

Objectives: In order to find control measures against bacterial leaf blight (BLB), one of the most destructive diseases of rice, the present study aimed to evaluate rice varieties cultivated in Togo and some near isogenic lines from IRRI for resistance to BLB in screen house. Methodology and Results: The lesions after inoculation with 13 X. oryzae pv. oryzae strains from Togo were evaluated on 21 rice varieties and near isogenic lines under screen house. The results revealed differential reactions of these genotypes in disease expression. AMMI analysis identified three groups of genotypes: resistant group made up of 12 lines IRBB1, IRBB2, IRBB3, IRBB4, IRBB7, IRBB8, IRBB10, IRBB11, IRBB13, IRBB14, IRBB21 and IR24, medium resistant group made up of three cultivars grown in Togo, NERICA4, NERICA8 and NERICA14, and one cultivar from AfricaRice, Giganté, and susceptible group including five genotypes TGR203 and IR841 from ITRA, NERICA19 and TOG5681 from AfricaRice, and the line IRBB5. Conclusions and application of findings: The results provided useful information indicating that none of rice varieties grown in Togo was resistant to bacterial leaf blight, thus revealed a potential risk of epidemics in the growing areas since these varieties were only medium resistant (NERICA4, NERICA8 and NERICA14) to susceptible (TGR203, IR841 and NERICA19). Besides, the present results are prerequisite for further screening under field conditions across ecozones of Togo (forest zone, forest savanna transition zone, wet savanna zone and dry savanna zone) and years to find out stable resistant varieties for durable production of ric