309 research outputs found

    Effect of Temperature on in vitro Survival of some Bradyrhizobium Strains

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    Evaluating Rhizobium survival in inoculants exposed to high temperature may be considered the first stage in identifying potential inoculant strains that would withstand temperature stress on inoculated seeds in the field. High temperatures may adversely affect the survival of Rhizobium in packaged inoculants during storage and inoculation (Somasegaran et al., 1984), and the viability of rhizobia in inoculants may be lost in a few weeks at temperatures of 350C or higher (Smith, 1987). Low storage temperature, however, is not always better than room temperature, as some slow growing bradyrhizobia were found to survive better at 260C than at 40C (Vincent, 1982). Soil temperature is also an important environmental variable that affects general biological activity. Nodulation and N2-fixation were observed under a wide range of temperatures with an optimum range between 20 and 300C. Elevated temperatures affect nodule initiation and development in temperate legumes, whereas, in tropical legumes it is mainly N2 fixation efficiency that is affected (Somasegaran et al., 1984). Temperature changes affect the competitive ability of Rhizobium strains and there are also specific temperature-sensitive Rhizobium legume combinations e.g. R. Legumino- sarum biovar-trifolii that forms nodules with Trifolium subterranium (Lewis-Henderson and Djordjevic, 1991(

    Understanding and Managing Aflatoxin Contamination in the Groundnut Value Chain in Nigeria

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    This manual is conceived to support awareness raising campaigns of the groundnut value chain actors in and out of the States targeted for the implementation of the USAID funded Groundnut Technology Upscaling Project in Nigeria. It is a fall-out of two capacity development events of the project - Media Training and Training of Trainers Workshops organized by ICRISAT in Kano during the first six months of project implementation in Nigeria. In view of the focus of the groundnut technology upscaling project on ensuring that farmers produce and market groundnuts free of Aflatoxins, the manual provides the general and specific information on Aflatoxin contamination and its management at all stages of the groundnut value chain. Though considered to be a basic companion document for front-line officers of partner institutions of the groundnut technology project, it can also be used by other actors of the groundnut value chain. The Manual is laid out in two parts; while Part 1 provides general and specific information required for the understanding of Aflatoxin, Part 2 focuses on the management of Aflatoxins at all stages of the groundnut value chain

    Pre-empting aflatoxin contamination in legume and cereal farming systems in Northern Nigeria: Case study of the groundnut value chain

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    The current emphasis by the government of Nigeria on boosting . agricultural productivity requires actors of the agricultural sector to develop sustainable agro-allied technologies that could enhance the quality of crop-livestock products. Aflatoxin is reported to be a major challenge of many legume and cereal value chains with potentially negative impacts on product marketing, and the health of people and livestock. This study presents preliminary results of pre-emptive measures being undertaken by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and national partners on the management of Aflatoxin contamination in the Groundnut Value Chain in selected States of Northern Nigeria. A combination of complementary approaches is being used to pre-empt aflatoxin contamination in the groundnut value chain. These include, the organization of Training of Trainers (ToT) workshops, development of aptitudes in the detection of aflatoxin levels, demonstration of onfarm options for managing aflatoxin contamination, production of pedagogic materials to support awareness raising campaigns, engagement of media organs to sustain awareness on the challenges of aflatoxin contamination, and evaluation of aflatoxin groundnut resistant genotypes. Above all, a total of 250 samples of groundnut and groundnut-based products have been collected from 16 out of the 19 States in Northern Nigeria to determine the prevalence and distribution of aflatoxin contamination. This paper presents progress on the outcomes of these interventions

    Gene Expression Signature of DMBA-Induced Hamster Buccal Pouch Carcinomas: Modulation by Chlorophyllin and Ellagic Acid

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    Chlorophyllin (CHL), a water-soluble, semi-synthetic derivative of chlorophyll and ellagic acid (EA), a naturally occurring polyphenolic compound in berries, grapes, and nuts have been reported to exert anticancer effects in various human cancer cell lines and in animal tumour models. The present study was undertaken to examine the mechanism underlying chemoprevention and changes in gene expression pattern induced by dietary supplementation of chlorophyllin and ellagic acid in the 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis model by whole genome profiling using pangenomic microarrays. In hamsters painted with DMBA, the expression of 1,700 genes was found to be altered significantly relative to control. Dietary supplementation of chlorophyllin and ellagic acid modulated the expression profiles of 104 and 37 genes respectively. Microarray analysis also revealed changes in the expression of TGFβ receptors, NF-κB, cyclin D1, and matrix metalloproteinases (MMPs) that may play a crucial role in the transformation of the normal buccal pouch to a malignant phenotype. This gene expression signature was altered on treatment with chlorophyllin and ellagic acid. Our study has also revealed patterns of gene expression signature specific for chlorophyllin and ellagic acid exposure. Thus dietary chlorophyllin and ellagic acid that can reverse gene expression signature associated with carcinogenesis are novel candidates for cancer prevention and therapy

    Current status of the multinational Arabidopsis community

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    The multinational Arabidopsis research community is highly collaborative and over the past thirty years these activities have been documented by the Multinational Arabidopsis Steering Committee (MASC). Here, we (a) highlight recent research advances made with the reference plant Arabidopsis thaliana; (b) provide summaries from recent reports submitted by MASC subcommittees, projects and resources associated with MASC and from MASC country representatives; and (c) initiate a call for ideas and foci for the “fourth decadal roadmap,” which will advise and coordinate the global activities of the Arabidopsis research community

    Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

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    Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

    Functionally Redundant RXLR Effectors from <em>Phytophthora infestans</em> Act at Different Steps to Suppress Early flg22-Triggered Immunity

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    Genome sequences of several economically important phytopathogenic oomycetes have revealed the presence of large families of so-called RXLR effectors. Functional screens have identified RXLR effector repertoires that either compromise or induce plant defense responses. However, limited information is available about the molecular mechanisms underlying the modes of action of these effectors in planta. The perception of highly conserved pathogen- or microbe-associated molecular patterns (PAMPs/MAMPs), such as flg22, triggers converging signaling pathways recruiting MAP kinase cascades and inducing transcriptional re-programming, yielding a generic anti-microbial response. We used a highly synchronizable, pathogen-free protoplast-based assay to identify a set of RXLR effectors from Phytophthora infestans (PiRXLRs), the causal agent of potato and tomato light blight that manipulate early stages of flg22-triggered signaling. Of thirty-three tested PiRXLR effector candidates, eight, called Suppressor of early Flg22-induced Immune response (SFI), significantly suppressed flg22-dependent activation of a reporter gene under control of a typical MAMP-inducible promoter (pFRK1-Luc) in tomato protoplasts. We extended our analysis to Arabidopsis thaliana, a non-host plant species of P. infestans. From the aforementioned eight SFI effectors, three appeared to share similar functions in both Arabidopsis and tomato by suppressing transcriptional activation of flg22-induced marker genes downstream of post-translational MAP kinase activation. A further three effectors interfere with MAMP signaling at, or upstream of, the MAP kinase cascade in tomato, but not in Arabidopsis. Transient expression of the SFI effectors in Nicotiana benthamiana enhances susceptibility to P. infestans and, for the most potent effector, SFI1, nuclear localization is required for both suppression of MAMP signaling and virulence function. The present study provides a framework to decipher the molecular mechanisms underlying the manipulation of host MAMP-triggered immunity (MTI) by P. infestans and to understand the basis of host versus non-host resistance in plants towards P. infestans
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