Variação sazonal e preditores ambientais do balanço oxidativo em um peixe anual neotropical

Abstract

Oxidative stress occurs when there is an imbalance between pro-oxidants and antioxidants in favor of the pro-oxidants, leading to a rupture of signaling and oxidative balance and/or molecular damage. Oxidative stress has been related to trade-offs between the characteristics of the life history and self-maintenance. Trade-offs are characterized by conflicts between the allocation of energy in one characteristic over another. Organisms that present rapid growth and large investments in reproduction exhibit higher production of oxygen-reative species (ROS) and oxidative stress related to declines in the activity of antioxidant enzymes. Oxidative stress can be influenced by environmental conditions. Annual fish exhibit life history characteristics related to increased ROS production, such as rapid growth, intense reproductive process and accelerated aging, and inhabit temporary pools with large environmental variations. Thus, the objective of this work was to evaluate oxidative balance markers (superoxide dismutase, catalase, glutathione S-transferase, lipoperoxidation and total proteins) throughout the life cycle of the neotropical annual fish species Austrolebias minuano, collected in a natural environment. Our results showed that the species presents an efficient antioxidant system during most of its life cycle, mainly in the reproductive phase in the females and in the senile period of life in males. Increased lipoperoxidation was evidenced only in females in the period corresponding to the growth phase. Males showed reduction in all analyzed markers, except in proteins, throughout life. The expected trade-offs between life and self-maintenance characteristics were exclusive between growth and automanutanation in females. In addition, we showed that the environmental variables influence the variation of the biomarkers analyzed during the life cycle of the species. These results suggest that the annual fishes present a well developed oxidative balance system adapted to face the unpredictability of temporary pools.