Identification of defence-related genes in banana against Fusarium Wilt

Bananas (Musa sp.) serve as a staple diet and source of income for millions of people worldwide. The crop, however, is vulnerable to several important diseases such as Fusarium wilt, caused by the soilborne fungus Fusarium oxysporum f.sp. cubense (Foc) . During the mid-20th century, thousands of acres of export banana plantations were lost in Central America due to Fusarium wilt. The epidemic was brought under control only by replacing the highly susceptible Gros Michel banana with Cavendish cultivars. Cavendish bananas, however, are susceptible to Foe race 4, a highly virulent variant of the pathogen that also causes disease to banana varieties susceptible to Foc races 1 and 2. Only this time, no resistant replacement varieties acceptable to the commercial market exist, while cultural and/or chemical control strategies proved to be ineffective for disease control. The only sustainable solution, thus, would be the improvement of existing banana varieties that are acceptable to consumers for resistance to Fusarium wilt. An understanding of how plants defend themselves against pathogens is an imperative first step towards the development of disease-resistant plants. Two broad defence mechanisms against pathogen attack exist in plants: Constitutive defence mechanisms that are pathogen non-specific and induced plant defence responses following recognition of specific pathogen features. A primary objective of this study was to elucidate induced banana defence responses. Induced defence responses may include the induction of regulator and antifungal proteins, the production of active-oxygen species or products from the phenylpropanoid pathway. A few studies have attempted to elucidate the genetic factors involved in the banana defence response but to date no clear answer has arisen. Forward and reverse genetics encompass approached by which plant defence responses can be studied; a particular technique of interest which can be classified under both forward and reverse genetics is cDNA-Amplified Fragment Length Polymorphism (AFLP) In a field trial conducted in an Foc-infested field in Kiepersol, South Africa, cultivars Rose and Calcutta IV proved resistant, and FHIA-17 tolerant to Foe 'subtropical' race 4 (VCG 0120) when compared to the highly susceptible Cavendish cultivar 'Williams'. The genetic basis of defence to Foc in FHIA-17, Rose and Calcutta IV was verified using quantitative real-time reverse transcriptase PCR (qRT-RT-PCR). Catalase, POX and PAE were strongly up-regulated in the tolerant and resistant banana varieties. These genes are involved in the oxidative burst and secondary metabolism leading to the phenylpropanoid pathway and cell wall strengthening. Resistance to Foc, 'subtropical' race 4, thus seems to depend on the early recognition of the pathogen and subsequent blocking of its progress into the plant's vascular system. The response of resistant and tolerant banana varieties to Foc was elucidated by analysing the banana transcriptome 6 and 72 hours post inoculation (hpi) using cDNA-AFLP. Seventy-six differentially expressed transcript derived fragments (TDFs) were isolated, sequenced and subjected to BLASTX and BLASTN searches. Many of the sequences were not significantly similar to any other sequences in the databases, but several genes fragments showed homology to defence-related genes. TDFs representing genes such as S-adenosylmethionine synthase (SAMS) and isoflavone reductase, which are potentially involved in the production of cell wall strengthening compounds such as lignin, were identified. Expression patterns of selected TDFs as seen on the cDNA-AFLP gels were confirmed using qRT -PCR. As additional endogenous controls, two TDFs which displayed constitutive expression on the cDNA-AFLP gels, were isolated, sequenced and were optimised for use as endogenous control genes for the normalisation of the qRT-PCR data. In most cases, the expression patterns seen on the cDNA-AFLP gels were replicated by qRT-PCR. This study concludes that the tolerant (FHIA-17) and resistant (Rose and Calcutta IV) banana varieties induced defence-related genes upon attack by Foc and that the cDNA-AFLP technique was further effective in identifying additional defence-related genes. Looking to the future, the greatest understanding of the defence responses induced during the banana/Foe interaction would be obtained by using additional molecular approaches or techniques. It is in some cases sufficient to look exclusively at transcriptomic i.e. cDNA-AFLP and microarray data to study the plant's response, however, a look at differential protein and metabolite expression would complement transcriptomic data and add insight into the fate of certain expressed genes. This would possibly speed up the identification of the defence pathways used by resistant bananas to resist infection by Foc, once identified these pathways can be manipulated in the susceptible plants and thus the generation of a Foc resistant banana could finally become a reality.Dissertation (MSc)--University of Pretoria, 2008.Microbiology and Plant Pathologyunrestricte

Understanding radionuclide migration from the D1225 Shaft, Dounreay, Caithness, UK

A 65 m vertical shaft was sunk at Dounreay in the 1950s to build a tunnel for the offshore discharge of radioactive effluent from the various nuclear facilities then under construction. In 1959, the Shaft was licensed as a disposal facility for radioactive wastes and was routinely used for the disposal of ILW until 1970. Despite the operation of a hydraulic containment scheme, some radioactivity is known to have leaked into the surrounding rocks. Detailed logging, together with mineralogical and radiochemical analysis of drillcore has revealed four distinct bedding-parallel zones of contamination. The data show that Sr-90 dominates the bulk beta/gamma contamination signal, whereas Cs-137 and Pu-248/249 are found only to be weakly mobile, leading to very low activities and distinct clustering around the Shaft. The data also suggest that all uranium seen in the geosphere is natural in origin. At the smaller scale, contamination adjacent to fracture surfaces is present within a zone of enhanced porosity created by the dissolution of carbonate cements from the Caithness flagstones during long-term rockwater interactions. Quantitative modelling of radionuclide migration, using the multiphysics computer code QPAC shows the importance of different sorption mechanisms and different mineralogical substrates in the Caithnesss flagstones in controlling radionuclide migration

Enlighten: Research Data terms and conditions for deposit of open research data

No abstract available

Combinatorics of compactified universal Jacobians

We use orientations on stable graphs to express the combinatorial structure of the compactified universal Jacobians in degrees g-1 and g over the moduli space of stable curves, \Mgb, and construct for them graded stratifications compatible with the one of \Mgb. In particular, for a stable curve we exhibit graded stratifications of the compactified Jacobians in terms of totally cyclic, respectively rooted, orientations on subgraphs of its dual graph.Comment: Final version, to appear in Advances in Mathematics. 41 page

'My teeth don't chew on shrapnel': an anthology of poetry by military veterans

This anthology, created by Oxford Brookes Poetry Centre, features poetry written by participants and associates of the Oxford Brookes Veterans' Poetry Workshop, 2019-20. Nine poets are represted here: Jo Young, Tom Laaser, Claire Hughes, Noel Harrower, John Thampi, Jamie Broady, Andrew Fassett, Stewart Hill, and Maggs Vibo. The anthology also includes an introduction by Niall Munro, an explanation of the workshop process by Susie Campbell, an essay about women veteran writers by Jane Potter, and reflections on her research into the perceptions of veterans in the UK and the US by Rita Phillips. Susie Campbell has also provided helpful writing prompts linked to the poems for those readers who are - or would like to be - writers. In addition to the four versions of the anthology, this package of files also includes transcripts of each of the interviews conducted by Dr Niall Munro with ten workshop participants, not all of whom appear in the anthology: Eugene Ratz, John Thampi, J. Robin Whitely, Jo Young (two interviews), Andrew Fassett, Tom Laaser, Stewart Hill, Claire Hughes, Maggs Vibo, and Jamie Broady. The transcriptions were completed by Dr Hester Bradley

Immune sensing of Candida albicans requires cooperative recognition of mannans and glucans by lectin and Toll-like receptors

Peer reviewedPublisher PD

RCT of the effect of berryfruit polyphenolic cultivar extract in mild steroid-naive asthma : a cross-over, placebo-controlled study

Objective: There is preclinical evidence that consumption of berryfruit extract may reduce chronic airways inflammation and modify airway remodelling in allergen-induced models of lung inflammation. We investigated the effect of berryfruit extract on the fractional expired nitric oxide (FeNO), a biomarker of eosinophilic airways inflammation, in adults with steroid-naïve asthma. Design: Randomised placebo-controlled cross-over double-blind trial. Setting: Single-centre community-based trial. Participants: 28 steroid-naïve mild asthmatics with FeNO >40 ppb, of whom 25 completed both study interventions. Interventions: Participants were randomised to receive, according to the cross-over design, 100 mg berryfruit polyphenolic extract (BFPE) or placebo for 4 weeks, with a 4-week washout period between the interventions. Primary outcome measure: The primary outcome variable was FeNO at 4 weeks, analysed by a mixed linear model, with a random effect for participant and baseline FeNo as a covariate. Results: The mean (SD) natural logarithm transformed (ln) FeNO after 4 weeks of treatment for the BFPE and placebo groups was 4.28 (0.47) and 4.22 (0.47), respectively. The paired change from baseline mean (SD) BFPE minus placebo ln FeNO was -0.03 (0.39), N=25. The mixed linear model estimate, with baseline covariate adjustment, difference in ln FeNO, was -0.002 (95% CI -0.15 to 0.14), p=0.98. This is equivalent to a ratio of geometric mean FeNO of 1.0 (95% CI 0.86 to 1.15). Conclusions: In steroid-naïve participants with mild asthma and elevated FeNO, there was no effect of BFPE on FeNO, a biomarker of eosinophilic airways inflammation. Caution is required in the extrapolation of apparent benefit in murine models of lung eosinophilia to clinical efficacy in patients with asthma