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Matthew LeFauve, Victoria P Connaughton; Impacts of heavy metal exposure on visual behavior and anatomy in zebrafish (Danio rerio). Invest. Ophthalmol. Vis. Sci. 2016;57(12):2763.
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© ARVO (1962-2015); The Authors (2016-present)
To determine if there were negative consequences of heavy metal exposure within a freshwater ecosystem using the zebrafish (Danio rerio) vertebrate experimental model.
This study was conducted on 125 zebrafish larvae of both sexes. Larvae were obtained by in-house spawning of wildtype adult animals and kept socially in standard petri dishes and were kept at a 14:10 light:dark cycle for the duration of the experiment. Beginning at 6 hours postfertilization (hpf), larvae were randomly placed into 1 of 5 experimental treatments: Control (no metal exposure), Low Cadmium (0.05 PPB), High Cadmium (0.5 PPB), Low Nickel (0.5 PPB), or High Nickel (15 PPB). The exposure lasted 72 hours, after which the larvae were removed from treatment and placed into system water. At 7, 9, and 11 days pf, subgroups of larvae (n = 10) were tested behaviorally using a novel optomotor response stimulus, euthanized, and fixed in 2% paraformaldehyde for later anatomical analysis. OMR responses to a black-and-white rotating pinwheel stimulus projected under the test container were assessed a posteriori through video recording by all occurrence scan sample behavioral analysis by a single observer. Videos were coded so the observer was blind to the exposure treatment of the subjects. Fish were scored as number of animals demonstrating a positive OMR. Gross morphology was assessed for larvae at each timepoint using a dissection microscope and ImageJ.
At 7dpf, larvae within the cadmium low concentration treatment had the longest average notochord length (4.814 mm); while larvae from the nickel low concentration group had the shortest (3.804 mm). Preliminary results suggest that by 9 dpf and 11 dpf, the metal exposed fish have a reduced body size in comparison to the control fish. OMR responses tested in 7dpf fish were reduced, in both the cadmium and nickel treatment groups.
The concentrations of cadmium and nickel found in the United States drinking water alter fish visually guided behavior and overall gross morphology with ingestion and integumentary exposure routes.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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