Meeting Abstract
Invasive species are a threat to biodiversity, and much research assessing the dispersal potential of invasive species has focused on immune responses. Immune responses can vary in energetic costs, and invaders are predicted to rely on less costly ones allowing for energy allocation to dispersal. Elevated stress from dispersal may also play a role. The cane toad (Rhinella marina) is a toxic amphibian that has been introduced to several parts of the world and is capable of rapid dispersal into new habitat. Previous studies have assessed immune parameters in these toads, but little research has evaluated responses at the gene expression level. RNA-sequencing (RNA-seq) of spleen tissue collected from cane toads 2hr post-subjection to an acute challenge of 2 µg*g body mass-1 lipopolysaccharide (LPS) revealed genes coding for multiple cytokines involved in innate immune responses such as phagocytic cell recruitment, extravasation, inflammation, and lymphocyte differentiation were significantly upregulated compared with sham-injected toads. Another group of toads were subjected to an acute stress response (via transdermal application of 15 µg of exogenous corticosterone (CORT) in peanut oil) both 1hr prior to and with LPS injection to maintain elevated CORT levels during the response, but this resulted in few differentially expressed genes compared with controls or the LPS treatment (which both received peanut oil application only). RNA-seq results were confirmed with qPCR. Although exogenous CORT did not alter the immune response to LPS 2hr post-injection, these results show the differentially expressed genes during a response to LPS, and give novel primers to assess immune investment among populations of this invasive toad.
