The zebrafish is a small freshwater fish native to Southeast Asia. Zebrafish were originally developed as a model system by Dr George Streisinger to study the genetic basis of behavior in vertebrates. This species was chosen because it is easy to maintain in captivity, reproduces weekly with large clutches, the embryos are optically clear allowing for the visualization of development, they develop rapidly, and the genome is sequenced. These characteristics have now allowed us to visualize neuronal activity in an intact behaving animal by expressing genetically encoded calcium indicators in selected neurons.

My lab studies how the environment affects the development of the olfactory sensory system and the resulting olfactory driven behaviors (Stephenson et al., 2011, 2012). We have used the zebrafish as a model system to dissect mechanisms of olfactory imprinting originally described in Pacific Salmon. We have shown that zebrafish make and maintain long-term olfactory memories or olfactory imprinting and this olfactory imprinting is correlated with changes in gene expression in the olfactory sensory neurons (Harden et al., 2006; Whitlock, 2006), including changes in olfactory receptor expression that are PEA-isoform specific (Calfun et al., unpublished). Thus an animal’s olfactory behavior is biased toward early life experiences.

Experience dependent learning of odors is important in “real” fish: through a study of the impact of salmon on native Chilean species we have shown that the puye (Galaxias maculatus) must learn to avoid the odors of Brown Trout (Salmo trutta fario) and Atlantic Salmon (Salmo salar) (both invasive species).

Studies using zebrafish have led to the discovery of a genome-wide duplication event in teleosts, evidence for extreme lateralization of visual behaviors and their underlying circuits, and the effects of lab rearing on the sex determination mechanisms in this species. The ramifications of these discoveries will be discussed.

Support: NIH/NIDCD 050820 (KW); FONDECYT 1111046 (KW); Instituto Milenio ICM- P09-022.F (KW, IB).