Hypersalinity and Hydrogen Peroxide Upregulation of Gene Expression of Antioxidant Enzymes in Ulva fasciata Against Oxidative Stress

Abstract

The modulation of manganese superoxide dismutase (MnSOD), FeSOD, ascorbate peroxidase (APX), glutathione reductase (GR), and catalase (CAT) gene expression and activities and antioxidants in Ulva fasciata against hypersalinity (90 per thousand)-induced oxidative stress was studied. Increases in H(2)O(2) contents but no changes in lipid peroxidation and protein carbonyl group contents suggest oxidative damage did not occur in 90 per thousand condition. Antioxidants were consumed for reactive oxygen species (ROS) scavenging indicated by decreased ascorbate and glutathione contents by 90 per thousand. Antioxidant enzymes were differently expressed by 90 per thousand for ROS removal. MnSOD activity and transcript increased 1 h after 90 per thousand treatment with a peak at hour 3, while FeSOD activity increased fast to the plateau after 1 h and its transcript increased after 3 h. APX activity increased 1 h after 90 per thousand but its transcript rose till 3 h, and GR activity increased after 1 h with a peak at hour 3 but its transcript increased till 3 h. CAT activity and transcript increased after 12 h. Enzyme activity is transcriptionally regulated by 90 per thousand except a fast increase in FeSOD, APX, and GR activities during 1 h. APX is responsible for early H(2)O(2) decomposition while CAT scavenges H(2)O(2) in the later period. The inhibition of 90 per thousand induced increase of H(2)O(2) content and FeSOD activity and transcript by treatment of a H(2)O(2) scavenger, dimethylthiourea, and the increase of FeSOD transcript of 30 per thousand grown thalli by H(2)O(2) treatment suggest that H(2)O(2) mediates the upregulation of FeSOD by hypersalinity while other enzymes is modulated by factors other than H(2)O(2).

Gene expression and antioxidant enzymatic activity in passion fruit exposed to aluminum

“…Induction of gene transcription after exposure to stress factors has also been reported by Balestrasse et al (2008) where elevated levels of Cat transcripts occurred in soybean nodules under cadmium stress. For Ulva fasciata, Sung et al (2009) reported an increase in the amplification of Cat genes after imposed to salt stress.…”

Changes of photosynthetic performances in mature thalli of the red alga Gelidium amansii (Gelidiaceae) exposed to different salinities

“…•− ) and hydroxyl radicals (OH − ) in macroalgae (Dring 2005;Lu et al 2006;Sung et al 2009;Kumar et al 2010;Liu & Pang 2010). The PBPs can effectively resist oxidative stress because of their nucleophilic ability to neutralize reactive oxidants (Cano-Europa et al 2010).…”

Salinity and Desiccation Induced Oxidative Stress Acclimation in Seaweeds

“…Phenotypic plasticity in antioxidant defence system in response to a variety of stress inducers has been documented in many higher plants (Apel & Hirt, 2004). The up-regulation of antioxidant enzymes including Mn/FeSOD, APX, GR and CAT in shortterm hypersalinity (90 S A ) (Sung et al, 2009) and APX, CAT in long-term hypersalinity (Lu et al, 2006) suggested that SOD and GR are critical for Ulva fasciata against oxidative stress. In general, subtidal macroalgal species have shown more sensitive to environmental fluctuations and thus generate more ROS compared to high intertidal species.…”

“…There are many evidences wherein antioxidant enzyme activities in marine algae have been altered in response to changes in environmental conditions (Collen & Davison, 1999 a,b;Lu, Sung, & Lee, 2006;Sung, Hsu, Wu, & Lee, 2009;Kumar & Reddy, 2012, pp. 1-160 and references therein). Further, up-regulation of FeSOD gene expression and its activity in hypersalinity were mediated specifically by H 2 O 2 , but MnSOD, APX, GR and CAT gene expression and corresponding enzyme activity were regulated by factors other than H 2 O 2 suggesting a dynamic nature of algal regulatory system in response to short-term hypersalinity that were likely changed after the long-term hypersalinity treatment (Sung et al, 2009). Higher level of antioxidant enzyme activities in intertidal U. lactuca (experiencing more harsh environmental conditions such as salinity variations and desiccation) compared to subtidal U. lactuca suggests that intertidal individuals detoxify H 2 O 2 more efficiently and are better adapted physiologically in coping with environmental stresses than subtidal individuals (Ross & Van Alstyne, 2007).…”