Nitrotyrosine is widely used as a marker of post-translational modification by the nitric oxide ( ⅐ NO, nitrogen monoxide)-derived oxidant peroxynitrite (ONOO ؊ ). However, since the discovery that myeloperoxidase (MPO) and eosinophil peroxidase (EPO) can generate nitrotyrosine via oxidation of nitrite (NO 2 ؊ ), several questions have arisen. First, the relative contribution of peroxidases to nitrotyrosine formation in vivo is unknown. Further, although evidence suggests that the one-electron oxidation product, nitrogen dioxide ( ⅐ NO 2 ), is the primary species formed, neither a direct demonstration that peroxidases form this gas nor studies designed to test for the possible concomitant formation of the two-electron oxidation product, ONOO ؊ , have been reported. Using multiple distinct models of acute inflammation with EPO-and MPO-knockout mice, we now demonstrate that leukocyte peroxidases participate in nitrotyrosine formation in vivo. In some models, MPO and EPO played a dominant role, accounting for the majority of nitrotyrosine formed. However, in other leukocyte-rich acute inflammatory models, no contribution for either MPO or EPO to nitrotyrosine formation could be demonstrated. Head-space gas analysis of heliumswept reaction mixtures provides direct evidence that leukocyte peroxidases catalytically generate ⅐ NO 2 formation using H 2 O 2 and NO 2 ؊ as substrates. However, formation of an additional oxidant was suggested since both enzymes promote NO 2 ؊ -dependent hydroxylation of targets under acidic conditions, a chemical reactivity shared with ONOO ؊ but not ⅐ NO 2 . Collectively, our results demonstrate that: 1) MPO and EPO contribute to tyrosine nitration in vivo; 2) the major reactive nitrogen species formed by leukocyte peroxidase-catalyzed oxidation of NO 2 ؊ is the one-electron oxidation product, ⅐ NO 2 ; 3) as a minor reaction, peroxidases may also catalyze the two-electron oxidation of NO 2 ؊

-common reed, is a perennial, emergent aquatic plant with annual cane-like stems developed from an extensive rhizome system. It grows in low-lying wet areas such as fresh and salt-water marshes, drainage ditches, shallow lake edges, sandy banks, roadsides, woodlands and rocky places. Stems can reach up to 6.0 m in height, vary in diameter from 4 to10 mm and have 10 to 25 cm long hollow internodes. Clones are extended by perennial rhizomes with extensive aerenchymatous tissue that supplies oxygen. Roots develop from rhizomes and other submerged parts of shoots. Leaves are smooth, alternate with narrow-lanceolate laminae, 20 to 70 cm long and 1 to 5 cm broad, and tapering to long slender points. The inflorescence is a terminal panicle, often 30 cm long, dull purple to yellow, with main branches bearing many spikelets. Seed production and germination are extremely variable and comparatively rare in many populations. Phragmites australis carries out photosynthesis through the C 3 pathway (or a variation thereof). Studies of genetic variation through isozyme and other molecular methods suggest that the populations are very closely related, and that variation in the metapopulation is small. Chloroplast DNA sequences of two non-coding regions indicate that non-native introduced genotypes of P. australis have displaced native genotypes in parts of North America. Phragmites australis often forms extensive monocultures in North America. As a consequence, habitat quality and species diversity have been documented to decline. However, in roadside populations it is effective in taking up many typical heavy metals that originate from nearby highways and buildings. Phragmites australis is found in all Canadian provinces and the Northwest Territories, but not in the Yukon Territory or Nunavut. The infestation of P. australis is most severe in the Great Lakes region and its migration is primarily mediated through rivers, canals and waterways but roadways are increasingly becoming important. Changes in the water regime have been linked to its success and could ultimately result in changes to the floristic composition of a habitat. Rodeo™, an aqueous solution of the isopropylamine salt of glyphosate, is most frequently used to control P. australis populations. Other methods of control include cutting, burning, and drainage of the species' habitat. As P. australis is considered to be invasive in North America, introduction of biological control agents is now being investigated. Can. J. Plant Sci. 84: 365-396. Le roseau commun Phragmites australis (Cav.) Trin. ex Steud. est une vivace aquatique dont le vaste système de rhizomes donne chaque année des tiges ressemblant à des cannes. L'espèce pousse dans les dépressions humides comme les marais d'eau douce et salants, les fossés de drainage, la rive des lacs peu profonds, les berges sablonneuses, le bord des routes, les boisés et les endroits rocailleux. Les tiges atteignent parfois jusqu'à 6,0 m de hauteur et leur diamètre varie de 4 à 10 mm, avec de longues sections creuses de 10 à ...

Isolevuglandins (isoLGs) are a family of reactive gamma-ketoaldehydes generated by free radical oxidation of arachidonate-containing lipids through the isoprostane pathway. Elevated plasma levels of isoLG protein adducts are observed in subjects with atherosclerosis compared with age/gender-matched controls. However, mechanisms for the generation of isoLGs in vivo are not established. Here we show that free radical-induced peroxidation promoted by the myeloperoxidase (MPO)/H2O2 system of leukocytes serves as one mechanism for the generation of isoLGs in vivo. Using a Candida sepsis model of inflammation, we demonstrate 3.5- and 2.7-fold increases in iso[4]LGE2 and isoLGE2 adducts of plasma proteins after pathogen exposure in wild-type mice. Plasma levels of F2 isoprostanes were not significantly increased after pathogen challenge in this model. MPO knockout mice demonstrated significant reductions (34%, P=0.003) in plasma levels of iso[4]LGE2 protein adducts after pathogen challenge compared with wild-type mice. Mass spectrometry and immunochemical methods demonstrate MPO-dependent formation of iso[4]LGE2 and isoLGE2 phospholipids and their corresponding isoLG protein adducts in model systems. The present studies thus identify MPO as one pathway for generation of isoLGs in vivo. They also suggest that long-lived protein isoLG adducts may serve as an alternative integrated sensor of oxidant stress in vivo.