title: Effect of cadmium on diaphorase activity and nitric oxide production in barley root tips.
abstract: The effect of Cd on NADPH-diaphorase activity and nitric oxide (NO) production was investigated in barley root tips. The Cd-induced increase of NADPH-diaphorase activity occurred at the elongation zone and increased further in the differentiation zone of barley root tips. This activity was associated primarily with the microsomal membrane fraction of crude extract. In situ analysis revealed that the diaphorase activity was localized in the metaxylem and metaphloem elements and to some cells of the pericycle and parenchyma of root tips. Cd-induced NO generation was observed in pericycle, parenchymatic stelar cells and companion cells of protophloem. The results suggest that the Cd-induced generation of NO functions in Cd toxicity through the ectopic and accelerated differentiation of root tips, causing the shortening of the root elongation zone and a subsequent reduction in root growth.
authors.affiliation: Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 14, SK-84523 Bratislava, Slovak Republic. katarina.durcekova@savba.sk
authors.forename: Katarína
authors.initials: K
authors.lastname: Valentovicová
authors.forename: L'ubica
authors.initials: L
authors.lastname: Halusková
authors.forename: Jana
authors.initials: J
authors.lastname: Huttová
authors.forename: Igor
authors.initials: I
authors.lastname: Mistrík
authors.forename: Ladislav
authors.initials: L
authors.lastname: Tamás
mesh_terms: D002104:Cadmium / Q000633:toxicity*; D003593:Cytoplasm / Q000187:drug effects / Q000201:enzymology; D001467:Hordeum / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D018519:Meristem / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D008861:Microsomes / Q000187:drug effects / Q000201:enzymology; D009252:NADPH Dehydrogenase / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis*; D017830:Octoxynol / Q000494:pharmacology; D010936:Plant Extracts / Q000378:metabolism
chemical_list: D010936:Plant Extracts; D002104:Cadmium; D009569:Nitric Oxide; D017830:Octoxynol; D009252:NADPH Dehydrogenase; D019331:NG-Nitroarginine Methyl Ester