Water mould exposure induces enzymatic antioxidant defences in embryos of the Two-colored Oval Frog (Elachistocleis bicolor) (Anura: Microhylidae)

Abstract

Water moulds are pathogens of amphibian eggs and embryos. However, little is known about oxidant or antioxidant status of amphibians in response to stress caused by water moulds. We exposed embryo stages of Two-colored Oval Frogs (Elachistocleis bicolor (Guérin-Méneville, 1838)) to a Saprolegnia-like species of water mould to explore homeostatic adjustments by the shifting of oxidative stress markers. We also tested whether water mould infection affected survivorship, hatching time, and morphology of hatching embryos. We found that the Saprolegnia-like species is a genuine stressor and substantially altered the physiological state of E. bicolor embryos. Among antioxidant defences, superoxide dismutase (SOD) and glutathione S-transferase (GST) activities increased in embryos exposed to the Saprolegnia-like species. However, no difference in lipid peroxidation levels was found between treatments, which might indicate that SOD and GST activations could be enough to prevent oxidative damage. Finally, we found higher mortality and number of malformations in the water mould treatment. We showed the stressful effect of water moulds on amphibian embryos, evidenced by the activation of their antioxidant system, and reveal the importance of considering physiological stress markers as key information when studying the potential consequences of disease outbreaks in the ecology and conservation of amphibians.

The Taxonomic Status of Physalaemus cuqui Lobo, 1993, with the Description of a New Species of Physalaemus (Anura: Leptodactylidae) from Argentina and Paraguay

“…2, their Table 1); Adedara et al (2020: 6); Andrade et al (2020: their Table 1); Antoniazzi et al (2020: 3013, 3015, 3017–3019, 3021–3022, their Figs. 1–4, their Tables 1–3); Bruhl € et al (2020: their Table 3); Cabral et al (2020: 1127); Cajade et al (2020: 10); Fernández et al (2020: 7); Ghirardi et al (2020: 412). [Misidentifications.]…”

Saprolegniosis in Amphibians: An Integrated Overview of a Fluffy Killer Disease

“…Based on the existing scientific literature, it is perceivable that the occurrence of saprolegniosis in amphibians is often attributed to a generic “water mold” infection without proper identification being made as to the species responsible for the infection [ 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. In most cases, when researchers attempt to identify the most probable infectious agent, taxonomic identification is based only on the morphological features of the isolates.…”

“…However, no difference in LPO levels was found between treatments, which might indicate that SOD and GST activation could be sufficient to prevent oxidative damage. Finally, they found a higher mortality and number of malformations in the water mold treatment group [ 27 ].…”