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CHARACTERIZATION OF LOCOMOTOR ACTIVITY OF ZEBRAFISH LARVAE: TEMPORAL VARIABILITY AND PHOTORESPONSE.
Citation:
BROOKS, J., R. C. MACPHAIL, D. L. HUNTER, B. K. PADNOS, AND S. J. PADILLA. CHARACTERIZATION OF LOCOMOTOR ACTIVITY OF ZEBRAFISH LARVAE: TEMPORAL VARIABILITY AND PHOTORESPONSE. Presented at Society of Toxicology, Seattle, WA, March 16 - 20, 2008.
Impact/Purpose:
As part of EPA’s effort to develop a rapid, in vivo, vertebrate screen for toxic chemicals, we have begun research to characterize the locomotor activity of 6-day post-fertilization (dpf) zebrafish (Danio rerio) larvae.
Description:
As part of EPA’s effort to develop a rapid, in vivo, vertebrate screen for toxic chemicals, we have begun research to characterize the locomotor activity of 6-day post-fertilization (dpf) zebrafish (Danio rerio) larvae. Larvae were individually housed and tested in 96-well microtiter plates; animals were kept at 26°C using a 14:10 light:dark cycle with lights on at 0830 hr. We used the Noldus tracking system to record locomotor activity (measured as total distance traveled) under two different lighting conditions: light (visible light) and dark (infrared light). First, it was necessary to know the optimal time window for testing during the day (i.e., stable overall baseline levels of activity from hour to hour). This was done by testing larvae at different times during the day under either lighting condition. The most stable period for assessing activity was between 1330 and 1630 hr (or at least 5 hr after the beginning of the light period). Second, we wanted to track the pattern of activity under alternating lighting conditions. To do this, larvae were acclimated in the dark for 5-10 min. Data collection began in visible light, followed by dark (infrared), across several cycles. Locomotor activity was low initially during visible light and then increased over the 10-min period. Switching to dark (infrared) produced a large initial increase in locomotor activity, followed by a gradual reduction across 10-min. Repeated changes in lighting conditions slightly reduced the overall level of activity, but did not alter the patterns of activity in either visible light or dark. The changes in locomotor activity to shifts in lighting conditions are reproducible in larval zebrafish, and may be useful in testing the effects of developmental exposure to toxic chemicals on behavioral transitions and habituation.