Expression of death-related genes and reactive oxygen species production in Skeletonema tropicum upon exposure to the polyunsaturated aldehyde octadienal

Abstract

<p>The effects of 4<em>E</em>/<em>Z</em>-octadienal (OCTA) on <em>ScDSP-1 </em>and <em>ScDSP-2 </em>gene expression and reactive oxygen species (ROS) production were investigated in the marine diatom <em>Skeletonema tropicum</em> (formerly <em>costatum</em>) using qRTPCR and flow cytometry. <em>ScDSP-1 </em>and <em>ScDSP-2 </em>genes have been previously shown to be involved in cell death in ageing cells and in response to photosynthetic stress. OCTA induced a differential, concentration-dependent <em>DSP</em> gene expression associated to ROS production, 821.6 and 97.7 folds higher for <em>ScDSP-1</em> and <em>ScDSP-2</em>, respectively. Among the concentrations tested, only 8 μM OCTA, which caused a reduction of 50% in cell concentrations at 24 h, was able to elicit an expression pattern consistent with a signalling role. Interestingly, only intermediate levels of reactive oxygen species (ROS) (<em>i.e</em>., 1.5±0.1 increase) were observed to be elicited by such concentration. These results suggest that ROS are key components of the molecular cascade triggered by polyunsaturated aldehydes (PUA) and leading to cell death. This could have implications for bloom final stages at sea, where PUA may act as effectors of diatom population dynamics through ROS acting as modulators.</p>