Abstract
Solar-powered sea slugs (Gastropoda: Sacoglossa) capture widespread interest due to their ability to steal chloroplasts from algae and withstand extended starvation – a process termed kleptoplasty. Despite this interest and potential practical applications, the cellular mechanisms behind kleptoplasty remain unidentified. Recent studies suggest that kleptoplastic slugs modify metabolic processes to suppress digestion, allow for photosynthetic production, and delay autophagy. This research will investigate the metabolic tradeoffs associated with kleptoplasty in order to elucidate the evolution of this ability. While photosynthesis produces beneficial carbohydrates, it also produces Reactive Oxygen Species (ROS) that cause oxidative damage and induce autophagy. Therefore, the slug’s role in promoting ongoing photosynthesis and the subsequent formation of ROS will be examined via biochemical assays, pharmacological inhibition experiments and in situ fluorescent staining. The effective neutralization of chloroplast-derived ROS has been hypothesized as a necessary step in the evolution of kleptoplasty so the slug’s overall antioxidant potential will be assessed using immunohistochemistry, electron microscopy and bioassays. Surveying multiple sacoglossan species with different kleptoplastic abilities and under varying environmental conditions is needed to identify which adaptations kleptoplastic slugs have evolved to counteract the effects of oxidative stress produced by their chloroplasts and highlight how kleptoplasty can provide ecological advantages such as enhanced starvation resistance and increased tolerance for warmer, hypoxic conditions. This research will contribute to our understanding of the evolution of kleptoplasty within the sacoglossan clade and chloroplast physiology and function, while laying the foundation for potential applications in medicine and the biofuel industry. It will also highlight important challenges for solar-powered animals when dealing with the warmer, deoxygenated oceans of the future.
Netherlands