Use of a New Tetrazolium-Based Assay to Study the Production of Superoxide Radicals by Tobacco Cell Cultures Challenged with Avirulent Zoospores of Phytophthora parasitica var nicotianae1

The relationship between the production of reactive oxygen species and the hypersensitive response (HR) of tobacco (Nicotiana tabacum L.) toward an incompatible race of the Oomycete Phytophthora parasitica var nicotianae has been investigated. A new assay for superoxide radical (O2−) production based on reduction of the tetrazolium dye sodium,3′-(1-[phenylamino-carbonyl]-3,4-tetrazolium)-bis(4-methoxy-6-nitro) benzene-sulfonic acid hydrate (XTT) has enabled the quantitative estimation of perhydroxyl/superoxide radical acid-base pair (HO2·/O2−) production during the resistant response. Tobacco suspension cells were inoculated with zoospores from compatible or incompatible races of the pathogen. Subsequent HO2·/O2− production was monitored by following the formation of XTT formazan. In the incompatible interaction only, HO2·/O2− was produced in a minor burst between 0 and 2 h and then in a major burst between 8 and 10 h postinoculation. During this second burst, rates of XTT reduction equivalent to a radical flux of 9.9 × 10−15 mol min−1 cell−1 were observed. The HO2·/O2− scavengers O2− dismutase and Mn(III)desferal each inhibited dye reduction. An HR was observed in challenged, resistant cells immediately following the second burst of radical production. Both scavengers inhibited the HR when added prior to the occurrence of either radical burst, indicating that O2− production is a necessary precursor to the HR.

Notes on the crayfishes in the United States National museum and the Museum of comparative zoölogy : with descriptions of new species and subspecies, to which is appended a catalogue of the known species and subspecies / by Walter Faxon.

v.40:no.8 (1914)

Transactions of the New Hampshire State Agricultural Society ...

1856

Ireland gets the new Trio Presidency off to a propitious start. CEPS Commentary, 30 August 2013

The Irish Presidency of the Council of the EU (January-June 2013) faced numerous challenges, not least of which was to negotiate the financial framework for the period 2014-2020 and the reform of the Common Agricultural Policy with the European Parliament, as well as the pressure to advance the banking agenda. Moreover, the fact that it was the start of a new Trio Presidency, the small size of the Irish administration and its fragile financial situation gave rise to some doubts as to how much it could achieve. Nevertheless, this post mortem on the Irish presidency finds that the Irish government approached the task with realism and optimism, a firm focus on results and the strong conviction that a good performance would enhance its reputation at home and in the EU. It is now for Lithuania and subsequently Greece, in the first half of 2014, to continue to tackle the remaining formidable challenges.