Presenter: Amanda Redmond
Mentor: William Cresko
Poster: 28
Major: Biology
Perchlorate is a known endocrine disruptor and a wide spread environmental contaminant that causes hypothyroidism in humans. Our previous work demonstrated that perchlorate results in a masculinizing effect in anadromous threespine stickleback (Gasterosteus aculeatus), but it is not known whether ecotypes of stickleback respond differently to this contaminant. Perchlorate has a known effect of suppressing thyroid hormone synthesis by competitively inhibiting the sodium-iodide symporter (slc5a5). The large slc5 gene family is associated with thyroid function and vitamin/mineral transport in all vertebrates. Using bioinformatic approaches we have identified that
there are several closely related genes to slc5a5 in stickleback including slc5a6a, slc5a6b, slc5a8a, and slc5a8b.
We investigate the effect of perchlorate on developmental gene expression in three genetically diverged populations of stickleback from Rabbit Slough (oceanic), Boot Lake (freshwater), and Riverbend (freshwater) ecosystems. We have developed RNA anti-sense probes for the NIS genes that we will be using for gene expression analysis using in situ hybridization to document the spatio-temporal expression of slc5a6a, slc5a6b, slc5a8a, and slc5a8b genes in each ecotype in response to perchlorate exposure. Because evolutionarily diverged populations of stickleback living in different habitats have different osmoregulatory and developmental nutrient needs, we hypothesize that a single chemical that affects solute transporters may have variable developmental effects among populations. In a preliminary study, we have mapped the temporal and spatial distribution of these genes in Rabbit slough (oceanic) fishes, and have found that they are expressed starting at 8-10 days in numerous tissues including the thyroid and the gonad. Our goal next is to identify gene expression patterns of the slc5 genes in the thyroid and gonad at 8, 14, and 30 days post fertilization (dpf) in the diverged populations, and to test for changes in spatial or temporal expression of the genes based on population, perchlorate treatement, and/or an interaction of both. We hypothesize that a gene by environment interaction (G-by-E) will lead to unique patterns of slc5a5 clade gene expression response to perchlorate in each of the three populations. Using cryosections of both control and 100ppm perchlorate treated fish we will determine the expression of these genes at 8, 14, and 30dpf. Our study will be relevant to understanding more about effects of toxin exposure between very genetically divergent populations of fish and other vertebrates, including humans.