Toxicity of Native and Invasive Apple Snail Egg Proteins on Developing Xenopus Laevis

Island Apple Snails (Pomacea maculata) are large aquatic snails in the family Ampularidae and considered one of the most detrimental invasive species in the world. Populations of P. maculata have been established on every continent except Antarctica where they disrupt the aquatic ecosystem. Once a population has infiltrated a suitable environment, they are difficult to remove due to their ability to aestivate, tolerance of low oxygen environments, and the toxicity of their eggs. P. maculata eggs contain an ovorubin protein that gives them a bright pink pigment, protects developing embryos from harsh environments, and has been proven to have neurotoxic effects on mice. To control P. maculata populations in the United States, egg masses are scraped into the water where developing snails die due to submersion. However, no previous studies have been done to evaluate the effects of P. maculata egg protein on developing aquatic organisms. In our studies we used standardized FETAX procedures to expose eggs of Xenopus laevis to varying concentrations of P. maculata egg proteins. In addition, we performed similar exposure procedures with egg proteins from the native Florida apple snail (Pomacea paludosa) to determine the novelty of this xenobiotic. Lastly, we experimented with methods of altering the protein, including filtration through a strong cation exchange column, and incubation of the protein at 24°C for varying amounts of time prior to exposure. Experiments using P. maculata egg extracts that were unaltered or slightly heat exposed had the lowest LC50s, while egg extracts that went through filtration or longer heat exposure had higher LC50s. The LC50 of P. paludosa egg extracts could not be determined due to low mortality at all concentrations. Results suggest that toxicity seen in our experiments is caused by P. maculata egg extract, which is novel to the invaded locations, and can persist in the environment for several days.https://digitalcommons.jsu.edu/ce_jsustudentsymp_2020/1012/thumbnail.jp