Cca-miR398 increases copper sulfate stress sensitivity via the regulation of CSD mRNA transcription levels in transgenic Arabidopsis thaliana

MicroRNAs play crucial roles during the process of plant development under stress conditions. Copper is an essential micronutrient for most organisms and serves as an important redox-active cofactor for various functional proteins. In the present study, we investigated the effects of copper sulfate stress on hickory (Carya cathayensis) root development. We identified that hickory cca-miR398 was related to copper sulfate stress response, targeting Copper/Zinc superoxide dismutases (cytosolic (CSD1) and chloroplastic (CSD2)) and a 5b subunit of mitochondrial cytochrome C oxidase (COX5b.1) that are linked directly to stress regulatory networks. The sequence of hickory cca-miR398 is highly similar to that of Arabidopsis miR398b and miR398c, regardless of one nucleotide variation. Therefore, target genes of cca-miR398 were investigated by using 5′-Rapid-amplification of cDNA ends. An overexpression of cca-miR398 in Arabidopsis caused a reduction not only in root length and cotyledon greening, but also in the CSD1, CSD2, and CSD3 transcription levels. These reductions had greater significance in transgenic Arabidopsis than in wild-type Arabidopsis under copper sulfate stress. The level of physiological indicators also changed in transgenic Arabidopsis. In addition, the expressions of copper-responsive microRNAs, such as miR397 and miR408, were affected by the copper sulfate stress. These results showed that CSD possesses the ability to enhance copper sulfate stress response in both transgenic Arabidopsis and hickory roots by increasing the production of superoxide dismutase. Our results also demonstrated that cca-miR398 weakens hickory tolerance to copper sulfate by regulating CSD targets.

Myocardial Protection from Ischemia-Reperfusion Damage by the Antioxidant Effect ofHibiscus sabdariffa Linnaeuson Metabolic Syndrome Rats

Cardiovascular diseases (CVD) constitute one of the most prevalent health problems worldwide, being strongly associated with metabolic syndrome (MS). Oxidative stress (OS) is present in both CVD and MS. Infusions ofHibiscus sabdariffa Linnaeus(HSL) have antioxidant properties and could therefore decrease the presence of OS in these diseases. The aim of this study was to evaluate myocardial protection during ischemia/reperfusion due to the antioxidant effect of HSL infusion (3%) on a MS rat model induced by the administration of 30% sucrose in drinking water. We determined in control, MS, andMS+HSLrat hearts (n=6per group) cardiac mechanical performance (CMP), coronary vascular resistance (CVR), and activities of manganese and copper/zinc superoxide dismutases (Mn and Cu/Zn-SOD), peroxidases, glutathione peroxidase (GPx), catalase (CAT), glutathione s-transferase (GST), glutathione reductase (GR), and glutathione (GSH). We also determined lipoperoxidation (LPO), total antioxidant capacity (TAC), and the nitrate/nitrite ratio (NO3-/NO2-). The treatment with the HSL infusion restored the CMP (p=0.01) and CVR (p=0.04) and increased the Mn- (p=0.02), Cu/Zn-SOD (p=0.05), peroxidases (p=0.04), GST (p=0.02) activity, GHS (p=0.02), TAC (p=0.04), and NO3-/NO2-(p=0.01) and decreased the LPO (p=0.02) in the heart of MS rats undergoing ischemia/reperfusion. The results suggest that the treatment with an infusion from HSL calices protects the cardiac function from damage by ischemia and reperfusion through the antioxidant activities of the substances it possesses. It favors antioxidant enzymatic activities and nonenzymatic antioxidant capacity.