Cross Talk among Calcium, Hydrogen Peroxide, and Nitric Oxide and Activation of Gene Expression Involving Calmodulins and Calcium-Dependent Protein Kinases in Ulva compressa Exposed to Copper Excess      

Abstract

To analyze the copper-induced cross talk among calcium, nitric oxide (NO), and hydrogen peroxide (H2O2) and the calcium-dependent activation of gene expression, the marine alga Ulva compressa was treated with the inhibitors of calcium channels, ned-19, ryanodine, and xestospongin C, of chloroplasts and mitochondrial electron transport chains, 3-(3,4-dichlorophenyl)-1,1-dimethylurea and antimycin A, of pyruvate dehydrogenase, moniliformin, of calmodulins, N-(6-aminohexyl)-5-chloro-1-naphtalene sulfonamide, and of calcium-dependent protein kinases, staurosporine, as well as with the scavengers of NO, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, and of H2O2, ascorbate, and exposed to a sublethal concentration of copper (10 μm) for 24 h. The level of NO increased at 2 and 12 h. The first peak was inhibited by ned-19 and 3-(2,3-dichlorophenyl)-1,1-dimethylurea and the second peak by ned-19 and antimycin A, indicating that NO synthesis is dependent on calcium release and occurs in organelles. The level of H2O2 increased at 2, 3, and 12 h and was inhibited by ned-19, ryanodine, xestospongin C, and moniliformin, indicating that H2O2 accumulation is dependent on calcium release and Krebs cycle activity. In addition, pyruvate dehydrogenase, 2-oxoxglutarate dehydrogenase, and isocitrate dehydrogenase activities of the Krebs cycle increased at 2, 3, 12, and/or 14 h, and these increases were inhibited in vitro by EGTA, a calcium chelating agent. Calcium release at 2, 3, and 12 h was inhibited by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and ascorbate, indicating activation by NO and H2O2. In addition, the level of antioxidant protein gene transcripts decreased with N-(6-aminohexyl)-5-chloro-1-naphtalene sulfonamide and staurosporine. Thus, there is a copper-induced cross talk among calcium, H2O2, and NO and a calcium-dependent activation of gene expression involving calmodulins and calcium-dependent protein kinases.

Hydrogen Peroxide Acts Upstream of Nitric Oxide in the Heat Shock Pathway in Arabidopsis Seedlings

“…It has also been reported that the level of H 2 O 2 increases following exposure to elevated temperatures, leading to HSF activation and HSP accumulation in Arabidopsis, tobacco (Nicotiana tabacum), and bacteria (Clostridium acetobutylicum; Volkov et al, 2006;Königshofer et al, 2008;Banti et al, 2010). In contrast, peroxide scavengers and inhibitors of H 2 O 2 generation have been shown to reduce HSP expression in HS-exposed Arabidopsis and tobacco, respectively (Volkov et al, 2006;Königshofer et al, 2008 (Delledonne et al, 1998;Murgia et al, 2004;Zago et al, 2006;Wilkins et al, 2011), antioxidant reactions , heavy metal resistance (González et al, 2012), and adventitious root formation (Bai et al, 2012). Proteomic analysis uncovered cross talk between NO and H 2 O 2 in citrus plants (Tanou et al, 2010).…”

Signal mediators at induction of heat resistance of wheat plantlets by short-term heating

“…Under the action of copper ions on the culture of sea alga Ulva compressa, the rise of the content of nitric oxide, hydrogen peroxide and calcium ions in cells was registered after 2 and 12 hours [8]. Thus the treatment of cells with the NO scavenger levelled the increase of the concentration of endocellular calcium, and the antagonists of calcium removed the rise of NO content.…”

Phytohormones and Nitric Oxide Interactions During Abiotic Stress Responses

“…In the alga Ulva compressa, NO is produced in response to high levels of cadmium, leading to Ca 2+ release in the cytosol and activation of calcium-dependent protein kinases (CDPKs) and calmodulins that lead to gene regulation responses. H 2 O 2 is also involved in this event, stimulating both Ca 2+ and NO production (Gonzáles et al 2012). …”