Time-delayed model of immune response in plants

In the studies of plant infections, the plant immune response is known to play an essential role. In this paper we derive and analyse a new mathematical model of plant immune response with particular account for post-transcriptional gene silencing (PTGS). Besides biologically accurate representation of the PTGS dynamics, the model explicitly includes two time delays to represent the maturation time of the growing plant tissue and the non-instantaneous nature of the PTGS. Through analytical and numerical analysis of stability of the steady states of the model we identify parameter regions associated with recovery and resistant phenotypes, as well as possible chronic infections. Dynamics of the system in these regimes is illustrated by numerical simulations of the model

Mannitol transport and mannitol dehydrogenase activities are coordinated in olea europaea under salt and osmotic stresses

This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Plant and Cell Physiology following peer review. The definitive publisher-authenticated version is available online at http://pcp.oxfordjournals.org/cgi/content/abstract/pcr121? ijkey=6orgUM5fkIjedYn&keytype=refThe intracellular accumulation of organic compatible solutes functioning as osmoprotectants, such as polyols, is an important response mechanism of several plants to drought and salinity. In Olea europaea a mannitol transport system (OeMaT1) was previously characterised as a key player in plant response to salinity. In the present study, heterotrophic sink models, such as olive cell suspensions and fruit tissues, and source leaves were used for analytical, biochemical and molecular studies. The kinetic parameters of mannitol dehydrogenase (MTD) determined in mannitol-growing cells, at 25 °C and pH 9.0, were as follows: Km, 54.5 mM mannitol and Vmax, 0.47 μmol h-1 mg-1 protein. The corresponding cDNA was cloned and named OeMTD1. OeMTD1 expression was correlated with MTD activity, OeMaT1 expression and carrier-mediated mannitol transport, in mannitol- and sucrose-growing cells. Furthermore, sucrosegrowing cells displayed only residual OeMTD activity, even though high levels of OeMTD1 transcription were observed. There is evidence OeMTD is regulated at both transcriptional and post-transcriptional levels. MTD activity and OeMTD1 expression were repressed after Na+, K+ and PEG treatments, both in mannitol- and sucrose-growing cells. In contrast, salt and drought significantly increased mannitol transport activity and OeMaT1 expression. Altogether, these studies support that olive tree copes with salinity and drought by coordinating mannitol transport with intracellular metabolism.This work was supported by the Portuguese Foundation for Science and Technology (FCT) (research project ref. PTDC/AGR-ALI/100636/2008; to A. Conde, grant ref. SFRH/BD/47699/2008; to C. Conde, grant ref. SFRH/BPD/34998/2007; to P. Silvagrant ref. SFRH/BD/13460/2003)

Exogenously-sourced ethylene increases stomatal conductance, photosynthesis, and growth under optimal and deficient nitrogen fertilization in mustard

In order to ascertain the stomatal and photosynthetic responses of mustard to ethylene under varying N availability, photosynthetic characteristics of mustard grown with optimal (80 mg N kg−1 soil) or low (40 mg N kg−1 soil) N were studied after the application of an ethylene-releasing compound, ethephon (2-chloroethyl phosphonic acid) at 40 days after sowing (DAS). The availability of N influenced ethylene evolution and affected stomatal conductance and photosynthesis. The effect of ethylene was smaller under deficient N where plants contained higher glucose (Glc) sensitivity, despite high ethylene evolution even in the absence of ethephon, potentially because the plants were less sensitive to ethylene per se. Ethephon application at each level of N increased ethylene and decreased Glc sensitivity, which increased photosynthesis via its effect on the photosynthetic machinery and effects on stomatal conductance. Plants grown with sufficient-N and treated with 200 μl l−1 ethephon exhibited optimal ethylene, the greatest stomatal conductance and photosynthesis, and growth. These plants made maximum use of available N and exhibited the highest nitrogen-use efficiency (NUE)

Economic burden of resected (stage IB-IIIA) non-small cell lung cancer in France, Germany and the United Kingdom: A retrospective observational study (LuCaBIS)

OBJECTIVES: New adjuvant treatments are being developed for patients with resected non-small cell lung cancer (NSCLC). Due to scarcity of real-world data available for treatment costs and resource utilization, health technology and cost-effectiveness assessments can be limited. We estimated the burden and cost-of-illness associated with completely resected stage IB-IIIA NSCLC in France, Germany and the United Kingdom (UK). MATERIALS AND METHODS: Eligible patients were aged ≥18 years with completely resected stage IB-IIIA NSCLC between August 2009 and July 2012. Patients (living or deceased) were enrolled at clinical sites by a systematic sampling method. Data were obtained from medical records and patient surveys. Direct, indirect and patient out-of-pocket expenses were estimated by multiplying resource use by country-specific unit costs. National annual costs were estimated based on disease prevalence data available from published sources. RESULTS: 39 centers provided data from 831 patients of whom patient surveys were evaluable in 306 patients. Median follow-up was 26 months. The mean total direct costs per patient during follow-up were: €19,057 (France), €14,185 (Germany), and €8377 (UK). The largest cost drivers were associated with therapies received (€12,375 France; €3694 UK), and hospitalization/emergency costs (€7706 Germany). Monthly direct costs per patient were the highest during the distant metastasis/terminal illness phase in France (€15,562) and Germany (€6047) and during the adjuvant treatment period in the UK (€2790). Estimated mean total indirect costs per patient were: €696 (France), €2476 (Germany), and €1414 (UK). Estimates for the annual national direct cost were €478.4 million (France), €574.6 million (Germany) and €325.8 million (UK). CONCLUSION: To our knowledge, this is the first comprehensive study describing the burden of illness for patients with completely resected stage IB-IIIA NSCLC. The economic burden was substantial in all three countries. Treatment of NSCLC is associated with large annual national costs, mainly incurred during disease progression

Adjuvant treatment patterns and outcomes in patients with stage IB-IIIA non-small cell lung cancer in France, Germany, and the United Kingdom based on the LuCaBIS burden of illness study

OBJECTIVES: To inform health-technology assessments of new adjuvant treatments, we describe treatment patterns in patients with complete resection of stage IB-IIIA non-small cell lung cancer (NSCLC) in France, Germany, and the United Kingdom (UK). MATERIALS AND METHODS: Data were collected via medical record abstraction. Patients were aged ≥18 years with completely resected stage IB-IIIA NSCLC, diagnosed between 01 January 2009 and 31 December 2011. Median follow-up was 26 months. Adjuvant treatment patterns and clinical outcomes were summarized descriptively. RESULTS: Among the 831 patients studied, 239 (29%) had stage IB disease, 179 (22%) had stage IIA disease, 165 (20%) had stage IIB disease, and 248 (30%) had stage IIIA disease. Adjuvant systemic therapy was received by 402 patients (48.4%), (France, 61.8%; Germany, 51.9%; UK, 33.4%). Use of adjuvant therapy increased with increasing stage of disease. Cisplatin/vinorelbine and carboplatin/vinorelbine were the most frequently prescribed adjuvant regimens. Median disease-free survival was 48.0 months (95% confidence interval [CI] 42.3-not estimable); the 25th percentile was 13.2 months (95% CI, 11.0-15.3). 204 patients (24%) died during the follow-up period. The median overall survival was not reached, the 25th percentile was 31.2 months (95% CI 26.8-36.0 months). 272 patients (33%) had disease recurrence during the follow-up period. For 86 of those patients, the first recurrence was local or regional with no distant metastasis and 14 had further progression to metastatic disease during the follow-up time. For the other 186 patients, the first recurrence involved distant metastases. A total of 200 patients had metastatic disease at any time during study follow-up. CONCLUSIONS: Less than half the patients with stage IB-IIIA NSCLC in this observational study received adjuvant systemic therapy. A high rate of first recurrence with distant metastatic disease was observed, emphasising the need for more effective systemic adjuvant therapies in this population

A Novel High-Affinity Sucrose Transporter Is Required for Virulence of the Plant Pathogen Ustilago maydis

A novel, high-affinity sucrose transporter identified in the plasma membrane of the plant pathogen Ustilago maydis is essential for fungal virulence and successful infection of maize

Sugarcane genes associated with sucrose content

<p>Abstract</p> <p>Background -</p> <p>Sucrose content is a highly desirable trait in sugarcane as the worldwide demand for cost-effective biofuels surges. Sugarcane cultivars differ in their capacity to accumulate sucrose and breeding programs routinely perform crosses to identify genotypes able to produce more sucrose. Sucrose content in the mature internodes reach around 20% of the culms dry weight. Genotypes in the populations reflect their genetic program and may display contrasting growth, development, and physiology, all of which affect carbohydrate metabolism. Few studies have profiled gene expression related to sugarcane's sugar content. The identification of signal transduction components and transcription factors that might regulate sugar accumulation is highly desirable if we are to improve this characteristic of sugarcane plants.</p> <p>Results -</p> <p>We have evaluated thirty genotypes that have different Brix (sugar) levels and identified genes differentially expressed in internodes using cDNA microarrays. These genes were compared to existing gene expression data for sugarcane plants subjected to diverse stress and hormone treatments. The comparisons revealed a strong overlap between the drought and sucrose-content datasets and a limited overlap with ABA signaling. Genes associated with sucrose content were extensively validated by qRT-PCR, which highlighted several protein kinases and transcription factors that are likely to be regulators of sucrose accumulation. The data also indicate that aquaporins, as well as lignin biosynthesis and cell wall metabolism genes, are strongly related to sucrose accumulation. Moreover, sucrose-associated genes were shown to be directly responsive to short term sucrose stimuli, confirming their role in sugar-related pathways.</p> <p>Conclusion -</p> <p>Gene expression analysis of sugarcane populations contrasting for sucrose content indicated a possible overlap with drought and cell wall metabolism processes and suggested signaling and transcriptional regulators to be used as molecular markers in breeding programs. Transgenic research is necessary to further clarify the role of the genes and define targets useful for sugarcane improvement programs based on transgenic plants.</p