Oxidative stress resistance in a short-lived Neotropical annual killifish.

Oxidative stress plays an important role in the evolution of aging and life history. High investments in life-history traits and environmental conditions can be associated with increased oxidative stress and aging process. However, to date, most studies that investigated variations in oxidative status were performed with long-lived vertebrates. Studies with short-lived vertebrates in wild are nonexistent. Annual killifishes have the shortest lifespans among vertebrates and inhabit temporary ponds subject to large variations in environmental conditions. In this sense, we investigated whether the high investment in growth and reproduction in a short-lived vertebrate and the large variations in environment has any cost in susceptibility to oxidative stress. We assessed the seasonal variation and the environmental correlates of four different oxidative status markers (lipid peroxidation and activity of the antioxidant enzymes Superoxide Dismutase, Catalase and Glutathione S-Transferase) along the life cycle of wild individuals of the Neotropical annual fish Austrolebias minuano. Males showed reduction in all biomarkers (except proteins) along their life cycle, while females showed increased oxidative stress only in the growth period. In addition, we showed that water physicochemical parameters, habitat structure and presence of co-occurring killifish species influenced the seasonal variation of the biomarkers. A. minuano showed an efficient antioxidant system for most part of their life cycle (mainly in males), suggesting a well-developed oxidative stress regulation system. We also show that annual fish mortality (mainly in males) apparently is not related to oxidative stress. Thus, environmental factors should drive annual fish aging and mortality.

Age-associated liver alterations in wild populations of Austrolebias minuano, a short-lived Neotropical annual killifish.

Aging processes have become an attractive field for researchers and annual fish have been used as biological models. However, the study on the changes in age-associated markers during the normal aging in wild populations of annual fish remains open. Austrolebias is a genus of Neotropical annual killifishes, distributed mainly in ephemeral pools across grassland floodplains of temperate South America and represent an emerging biological model for aging research, but studies investigating rapid aging and senescence in this genus of annual fish are almost non-existent. This study was undertaken to examine the changes in age-associated liver markers at the different developmental stages in wild populations of Austrolebias minuano. We demonstrate that A. minuano has a number of liver alterations of different severities throughout the life cycle, suggesting that these changes tend to increase with age. Our results revealed that > 70% of the analyzed livers presented alterations. Thus, our study should instigate new approaches on aging using Neotropical annual fish, and could be useful to improve the knowledge already provided by consecrated biological aging models as e.g. Nothobranchius killifishes.