Environmental signals (light, temperature, etc.) regulate a diverse array of biological processes. My research is involved in deciphering the cascade of events, beginning with environmental signals and ending with changes in gene expression, which regulate physiological processes. Further, we are interesting in understanding how environmental chemicals can disrupt these signaling processes. Our primary focus has been upon understanding the signaling cascade responsible for environmental sex determination using the water flea (Daphnia sp.) as a model organism. Our research has led to the discovery of environmental cues that signal the production of male offspring, the hormones that perpetuate the signal within the animals, and the identification of environmental chemicals that can mimic the hormones and disrupt normal sex ratios. Presently, we are evaluating the role of nuclear receptors as mediators of the hormonal signal leading to changes in gene transcription. Results from this research has increased our basic understanding of environmental signaling processes and has aided regulatory agencies in identifying environmental chemicals that can have profound effects on populations by disrupting these processes.
Research Areas: endocrine toxicology, mixtures toxicology, environmental signaling
Wang Y.H., Kwon G., Li H., and LeBlanc G.A. 2011. Tributyltin synergizes with 20-hydroxyecdysone to produce endocrine toxicity. Toxicol. Sci., 123: 71-79.
Hannas B.R., Wang Y.H., Thomson S., Kwon G., Li H., and LeBlanc G.A. 2010. Regulation and dysregulation of vitellogenin mRNA accumulation in daphnids (Daphnia magna). Aquatic Toxicol., 101:31-357.
Hannas, B.R., Das, P.C., Li, H. and LeBlanc, G.A. 2010. Intracellular conversion of environmental nitrate and nitrite to nitric oxide with resulting developmental toxicity to the crustacean Daphnia magna. PLoS ONE. 5:212453. Doi: 10.1371/journal.pone.0012453.
Hannas B.R., Wang Y.H., Baldwin W.S., Li Y., Wallace A.D., LeBlanc G.A. 2010. Interactions of the crustacean nuclear receptors HR3 and E75 in the regulation of gene transcription. Gen. Comp. Endocrin. 167: 268-278.
Thomson S., Baldwin W.S., Wang Y.H., Kwon G., LeBlanc G.A. 2009. Annotation, phylogenetics, and expression of the nuclear receptors in Daphnia pulex, BMC Genomics, 10:500.