It is almost time for the 9th European Zebrafish Meeting in Oslo, Norway! So here are a couple of recent publications on zebrafish research to get you in the mood.
Early toxin exposure effects throughout zebrafish life
The first two studies, both conducted at Duke University in Durham (NC, USA), are great examples of investigations into the neurobehavioral effects of toxin exposure at a young age and throughout adolescence and adulthood. All the experiments in these studies incorporated the use of automated video tracking to measure parameters like distance travelled, velocity, and distance from the bottom or a tank wall. It was even used to control taps given by a solenoid in a startle-response test.
Insecticides and pollution
The first of these studies investigated the neurobehavioral effects of imidacloprid, a popular insecticide that has recently fallen under scrutiny and is already restricted for use in the European Union. Imidacloprid mimics the effect of nicotine, paralyzing and eventually causing death to insects. Although it is currently the most widely used insecticide in the world, the lack of literature on the subject did not escape Emily Crosby and her colleagues’ notice. They set out to investigate this neonicotinoid’s effects in zebrafish and recently published their results in the Neurotoxicology and Teratology Journal.
Effects throughout life
Zebrafish exposed to imidacloprid at the larval stage saw a negative effect on their motility during the dark phases of an activity test in DanioVision. Effects persisted during adolescence and adulthood. For example, there was hyperactivity and a lack of habituation to a tap-elicited startle response in the exposed adolescent fish. Similar results, although not reaching significancy, were found in adult fish. During a novel tank test and predator avoidance test, exposed fish also showed more anxiety behavior by staying closer to the bottom. Shoaling behavior seemed unaffected.
Flame retardant metabolites
Laura Macaulay, also at Duke University, conducted similar tests on larval and juvenile zebrafish to study the effects of a PBDE metabolite. PBDE was once widely used as a flame retardant in consumer goods, but its use was phased out. Although the effects of PBDE are studied intensively, the effects of certain metabolites, thought to be much more toxic, are not. This is what Macaulay intended to investigate.
Anxiety and hyperactivity
Zebrafish were exposed to low doses of 6-OH-BDE-47 during the embryonic stage, which caused significant hypoactivity during the light phases of the DanioVision test. When fish were tested as juveniles, the exposure’s long-term effects were evidenced by increased anxiety-like behavior and hyperactivity in a novel tank test and the tap-elicited startle reflex test.
Water motion and stereotyped response
A completely different zebrafish experiment comes from Antonia Groneberg of the Max Planck Institute for Medical Research in Heidelberg, Germany. Groneberg et al. showed that larval zebrafish are able to detect minute water motions and respond to it in a stereotyped way. Interestingly, the entire experiment was pre-programmed with EthoVision XT.
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- Automatically track zebrafish in any developmental stage
- Suitable for tracking in any arena, from multi-well plate to mazes for adult fish
- A range of parameters for individual swimming patterns to group behavior
Fully automated swimming chamber
Their set-up consisted of a custom swimming chamber with a video camera and equipment to cause gentle movement in the water, but only when the animal was detected within a center zone of the swimming chamber. As you can imagine, manual control of the equipment and sounds made by the experimenters might have caused unintentional motion in the water and biased the results, so EthoVision XT was used to detect the location of the larvae and control the connected hardware. In this way, delay in response by the experimenter was also eliminated.
Groneberg and her colleagues used several protocols to perform a very detailed study of zebrafish responses to water flow, which we will elaborate on in another post. So keep an eye on this blog! (Or if you can’t wait, you can access the publication here.)
That’s it for today! But if you want to read on, check out this blog post, also listing a bunch of interesting zebrafish studies!
- Crosby, E.B.; Bailey, J.M.; Oliveri, A.N.; Levin, E.D. (2015). Neurobehavioral impairments caused by developmental imidacloprid exposure in zebrafish. Neurotoxicology and Teratology 49, 81-90.
- Groneberg, A.H.; Herget, U.; Ryu, S.; De_Marco, R. (2015). Positive taxis and sustained responsiveness to water motions in larval zebrafish. Frontiers in Neural Circuits, doi: 10.3389/fncir.2015.00009.
- Macaulay, L.J.; Bailey, J.M.; Levin, E.D.; Stapleton, H.M. (2015). Persisting effects of a PBDE metabolite, 6-OH-BDE-47, on larval and juvenile zebrafish swimming behavior. Neurotoxicology and Teratology, doi:10.1016/j.ntt.2015.05.002.