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Effects of lighting and time of day on the locomotion of zebrafish larvae.
Citation:
MACPHAIL, R. C., J. Brooks, D. L. HUNTER, T. D. Irons, AND S. J. PADILLA. Effects of lighting and time of day on the locomotion of zebrafish larvae. Presented at Fourth Aquatic Animal Models of Human Disease Conference, Durham, NC, January 31 - February 03, 2008.
Impact/Purpose:
To support criteria of MYP
Description:
The increasing use of zebrafish in developmental research highlights the need for detailed behavioral investigations in this species. Behavior represents the unique interface between the intrinsic and extrinsic forces that determine an organism’s health and survival. We have studied the locomotion of individual zebrafish larvae (6 dpf) by manipulating time-of-day and lighting conditions. Movement in 96-well microtiter plates was sampled every 200 msec, in sessions lasting up to 70 min, using the Noldus video tracking system. Locomotion data were analyzed with EthoVision software, and summarized as distance moved in cm. Time-of-day results indicated locomotion in darkness decreased gradually from early morning to a stable level with low variability between 13:00 and 17:00 hr. All further experiments were conducted during this time window. Locomotion in darkness was first recorded for 10-20 min after transfer to the recording platform. Locomotion during this initial dark period increased to a maximum then decreased steadily. Switching next to visible light reduced activity initially, followed by a gradual increase. A return to darkness produced a substantial increase in activity that quickly reached a maximum, after which it declined steadily. Activity in this second dark period exceeded the level obtained in the initial dark period. Varying the duration of the initial dark period (10-20 min) did not affect subsequent activity in either light or dark. The activity increase in the second dark period depended on duration of the preceding light period, being greater following a longer duration (15 min) than a shorter (5-min) one. Activity patterns in light and dark were reproducible across repeated cycles of lighting change (see figure below). These results show that locomotion in larval zebrafish can be reliably measured over time, and is sensitive to both time-of-day and lighting conditions. The results further suggest visible light initially inhibits locomotion, and darkness initially releases locomotion from inhibition. The subsequent activity increases in visible light, and the decreases in darkness, may indicate both behavioral processes display habituation. This is an abstract of a proposed presentation; the information does not necessarily reflect Agency policy. T.D. Irons is supported by the NIH NIGMS Initiative for Maximizing Student Diversity Figure: Influence of lighting conditions on locomotion in larval zebrafish. Light onset decreased locomotion and dark onset increased locomotion. Recovery of activity is evident in both lighting conditions. Repeated cycles of alternating lighting did not greatly influence locomotion.