Evaluation of stress responses to water molds in embryos of Physalaemus albonotatus (Anura: Leptodactylidae)

Abstract

Infections by water molds of the genus Saprolegnia (Oomycetes) have been associated with the death ofeggs and embryos in many anuran species; however, how water molds induce physiological responses in early andsusceptible developmental stages of anurans is poorly known. To assess whether or not embryos of Physalaemusalbonotatus (immobile and susceptible life stages) respond to Oomycetes infection, we performed a 4-d experimentexposing early stage embryos to the water mold Saprolegnia-like sp. We assessed mortality, hatching time, andoxidative stress (antioxidant enzyme activities and lipid peroxidation levels). Presence of water molds in infectedembryos was not evident to the naked eye until 1 to 1.5 d after inoculation. Mortality was significantly higher in thewater mold treatment than in the control treatment. Embryos exposed to Saprolegnia-like sp. hatched 24 h earlierthan those in control treatment. Among enzymatic activities, only catalase enzyme showed a significant depletionin embryos exposed to water molds compared to control groups. These results emphasize the need to exploreoxidative stress markers along with embryonic development at key stages, focusing on those early stages wherehatching is induced by water molds infection.