A Biostimulant Seed Treatment Improved Heat Stress Tolerance During Cucumber Seed Germination by Acting on the Antioxidant System and Glyoxylate Cycle

Seed enhancement technologies have the potential to improve germination and seedling growth under environmental stress. The effects of KIEM®, an innovative biostimulant based on lignin derivatives and containing plant-derived amino acids and molybdenum, were investigated on cucumber (Cucumis sativus L.) seed germination. To determine the metabolic targets of this product, biometric, transcriptional and biochemical analyses were carried out on both non-treated and KIEM®-treated seeds incubated for 24 and 48 h under standard (28°C) and heat stress (35°C) conditions. The application of the biostimulant as a seed treatment increased the percent germination (+6.54%) and fresh biomass (+13%) at 48 h, and decreased the content of H2O2 in treated seeds at 28°C (−70%) and at 35°C (−80%). These changes in biometric and biochemical properties were accompanied by changes in expression levels of the genes coding for ROS-producing (RBOH) and scavenging (SOD, CAT, GST) enzymes and their specific activity. In general, the treatment with KIEM® in heat-stress condition appeared to stimulate a higher accumulation of three scavenger gene transcripts: CuZnSOD (+1.78), MnSOD (+1.75), and CAT (+3.39), while the FeSOD isoform was dramatically downregulated (0.24). Moreover, the amount of non-protein thiols, important antioxidant molecules, was increased by the biostimulant after 48 h (+20%). Taken together these results suggest that KIEM® acts through mitigation of the effects of the oxidative stress. Moreover, after 48 h, the pre-sowing treatment with KIEM® increased the transcription levels (+1.5) and the activity of isocitrate lyase (+37%), a key enzyme of the glyoxylate cycle, suggesting a potential effect of this product in speeding up the germination process. Finally, the chemical characterization of KIEM® identified five essential and three non-essential amino acids, and others bioactive compounds, including five organic and inorganic acids that might be potentially involved in its activity. Based on these data, insights on the potential mechanism of action of the biostimulant, suggested that there are broader applications as a product able to increase seed tolerance to different abiotic stress typical of adverse environmental conditions.</p

Plan optimization for mediastinal radiotherapy: Estimation of coronary arteries motion with ECG-gated cardiac imaging and creation of compensatory expansion margins

BACKGROUND AND PURPOSE: Inadvertent heart and coronary arteries (CA) irradiation may increase the risk of coronary artery disease (CAD) in patients receiving thoracic irradiation. To date, the entity of cardiac-related CA displacement and the possible margins to be used for planning organs at risk volume (PRV) have been poorly described. Aim of this study was to quantify CA displacement and to estimate PRV through the use of ECG-gated computed tomography (CT) scans. MATERIAL AND METHODS: Eight patients received an ECG-gated intravenous contrast enhanced CT for non-cancer related reasons. Nine data sets were reconstructed over the entire R-R cycle with a dedicated retrospective algorithm and the following structures were delineated: Left main trunk (LM), left anterior descending (LAD), left circumflex (CX) and right coronary artery (RCA). CA displacements across the different cardiac phases were evaluated in left-right (X), cranio-caudal (Y) and anteroposterior (Z) directions using the McKenzie-van Herk formula (1.3 * Σ + 0.5 * σ). RESULTS: The following CA displacements were found in X, Y and Z coordinates: 3.6, 2.7 and 2.7 mm for LMT, respectively; 2.6, 5.0 and 6.8 mm for LAD, respectively; 3.5, 4.5 and 3.7 mm for CX, respectively; 3.6, 4.6 and 6.9 mm for RCA, respectively. Based on the mean displacements, we created a PRV of 3 mm for LM, 4 mm for CX and 5 mm for LAD and RCA. CONCLUSION: CA showed relevant displacements over the heart cycle, suggesting the need for a specific PRV margin to accurately estimate the dose received by these structures and optimize the planning process