Rapid light-induced shifts in opsin expression: finding new opsins, discerning mechanisms of change, and implications for visual sensitivity

Light induced shifts in cone frequency and opsin expression occur in many aquatic species. Yet little is known about how quickly animals can alter opsin expression and, thereby, track their visual environments. Similarly, little is known about whether adult animals can alter opsin expression or whether shifts in opsin expression are limited to critical developmental windows. We took adult wild caught bluefin killifish (Lucania goodei) from three different lighting environments (spring, swamp, variable), placed them under two different lighting treatments (clear vs. tea-stained water), and monitored opsin expression over four weeks. We measured opsin expression for five previously described opsins (SWS1, SWS2B, SWS2A, RH2-1, LWS) as well as RH2-2 which we discovered via 454 sequencing. We used two different metrics of opsin expression. We measured expression of each opsin relative to a housekeeping gene and the proportional expression of each opsin relative to the total pool of opsins. P...