title: Nitric oxide suppresses growth and development in the unicellular green alga Micrasterias denticulata.
abstract: Nitric oxide (NO), a key molecule in inter- and intracellular signalling, is implicated in developmental processes, host defense, and apoptosis in higher plants. We investigated the effect of NO on development in the unicellular green alga, Micrasterias denticulata, using two different NO donors, S-nitroso-N-acetyl-dl-penicillamine (SNAP) and sodium nitroprusside (SNP). Investigations at the light microsopic level revealed that both NO donors suppressed cell growth. Ultrastructural analyses were performed with SNAP- as well as SNP-treated cells and, additionally, with the control compound N-acetyl-d-penicillamine (NAP). Cells incubated with NO donors lacked a secondary wall and dictyosomal function was impaired, whereas NAP-treated cells showed no difference in development and organelle structure compared to control cells. Moreover, cisternae of the Golgi stacks were slightly involute and no vesicles were pinched off after SNAP and SNP incubation. The NO scavenger cPTIO (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, potassium salt) abrogated the effect of SNP, thus confirming that inhibition of cell growth is due to nitric oxide. Addition of iodoacetic acid, an inhibitor of cysteine-containing enzymes, like glyceraldehyde-3-phosphate dehydrogenase (GAPDH), evoked similar effects on cell growth and secondary wall formation as obtained by treatment with NO donors. Therefore, we hypothesize that NO inhibits activity of enzymes involved in the secretory pathway, such as GAPDH, via S-nitrosylation of the cysteine residue and, consequently, modulates cell growth in M. denticulata.
authors.affiliation: Cell Biology Department, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria.
authors.forename: Christine
authors.initials: C
authors.lastname: Lehner
authors.forename: Hubert H
authors.initials: HH
authors.lastname: Kerschbaum
authors.forename: Ursula
authors.initials: U
authors.lastname: Lütz-Meindl
mesh_terms: D001565:Benzoates / Q000494:pharmacology; D001681:Biological Assay; D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism; D002480:Cellulase / Q000378:metabolism; D000460:Chlorophyta / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development* / Q000648:ultrastructure; D003497:Cyclic N-Oxides / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000037:antagonists & inhibitors; D007093:Imidazoles / Q000494:pharmacology; D019807:Iodoacetic Acid / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D015388:Organelles / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D013997:Time Factors
chemical_list: D001565:Benzoates; D003497:Cyclic N-Oxides; D016166:Free Radical Scavengers; D007093:Imidazoles; D020030:Nitric Oxide Donors; C079393:1,3-dihydroxy-4,4,5,5-tetramethyl-2-(4-carboxyphenyl)tetrahydroimidazole; D009599:Nitroprusside; C079391:2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; D009569:Nitric Oxide; D026423:S-Nitroso-N-Acetylpenicillamine; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D002480:Cellulase; D019807:Iodoacetic Acid