Estabelecimento de marcadores funcionais em oócitos dos corais mussismilia hartii e mussismilia braziliensis

Abstract

Corals have a symbiotic relationship with zooxanthellae, microalgae associated with the animal's tissue, responsible for most of its daily energy gain. Warming ocean water breaks symbiosis, a phenomenon known as bleaching. Without their main nutritional source, corals depend on heterotrophy to survive, which can lead to stagnation of the reproductive cycle. There are corals, however, that manage to maintain gametogenesis even when bleached, however the physiology of these gametes in such a situation is unknown. In this work, we quantify and evaluate the oxidative balance of oocytes released from healthy colonies of Mussismilia braziliensis; in addition to oocytes from three colonies of Mussismilia harttii with different health conditions: one bleached, one partially bleached and one healthy. We also compared the oxidative balance between healthy colonies of the two species. Oocytes were frozen along a post-spawning time curve (0, 5 and 10 h) to assess oxidative balance during cell life and cell effort to remain healthy. Total protein levels, the activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) and the levels of lipoperoxidation (TBARS), a marker of lipid damage, were measured. In M. braziliensis, SOD activity increased between 5 and 10h after spawning, as well as lipoperoxidation between 0 and 10h. When comparing the oocytes from corals with different health conditions in M. harttii, no difference was found between the parameters studied during the post-spawning time, except for SOD at 0h. These organisms seem to preserve the quality of female gametic cells even after 10 hours of spawning. This response may be related to the intensification of heterotrophy, ensuring nutritional support and thus reproductive effort and quality of gametes even in bleached corals. When comparing the parameters between the healthy colonies of the two species, we verified that they differed in all the parameters analyzed in the 5h post spawning and in the SOD at 10am, showing a species-specific pattern for these biomarkers.