New information and developments in the zebrafish lab

Hello all,

After a few weeks in the zebrafish lab, mixed results have been obtained. Results are results, though, so I will take this post to share with you what we have gathered so far about the zebrafish and where we are headed in the coming weeks.

My project’s full title is “Embryonic ethanol exposure in the zebrafish: Effects on learning and memory”. As amusing as it is to some to “get fish drunk”, we (Professor Hunt, Bailey Jordan, and I) are very interested in seeing how embryonic ethanol exposure in the zebrafish affects learning and memory when the fish are fully developed. This project seeks to extend the zebrafish model to the study of learning and memory impairments in Fetal Alcohol Spectrum Disorders (FASD) specifically. Deformities and impairments vary depending on factors like the amount of alcohol and the timing of exposure to alcohol.

To test for deficits in learning and memory, we have used two tests. The first is the novel object recognition task  and the second is the novel location recognition task. These procedures have been used with rats in the past. Below is an image which depicts the novel object task (from http://blog.cirm.ca.gov/2015/02/19/clearing-up-chemobrain-cancer-therapy-induced-memory-problems-reversed-by-stem-cells/)
novel-object-recog-test1 (1)

The core of this test is that the rat is allowed to learn about the objects in the first stage but then the objects are taken away for some period of time. In the second stage, the objects are returned to their original locations, except one object is different. One would expect that a rat with normal learning and memory capability would investigate the new object more than the old since it is unfamiliar. There is also a novel location task in which the objects remain the same but one of them is in a different location in the test phase. Likewise, one would expect a rat with normal learning and memory ability to investigate the new location object more than the object with the same location.

Using a fish tank, we devised a way to perform these tests with the same basic idea. The hypothesis was that, in general, the fish would show a preference for exploring the new location or new object in the tank. We recorded the fish during these tasks and found mixed results upon analysis of the videos. Sometimes the fish would explore the new object or new location object more than the one which was the same. Although we have yet to statistically analyze the data (we measured time in seconds that the fish spent around each object), it seems as though most of the fish actually showed a preference for the more familiar object or location. Although this conflicts with some preliminary data Professor Hunt collected last semester, it is totally possible that the fish would prefer familiarity with this kind of test.

One qualm that we had about the procedure was its aversiveness. Whoever was testing the fish had to place the objects in the tank, that is, reach down and place the objects in the necessary locations. It was clear from the analysis of the videos that this caused the fish much stress. For some fish, it could take 15-20 seconds for them to stop swimming around the tank rapidly and return to focus on the objects. In the test phase, especially if the fish are still uneasy or rattled, the new object may represent something they are more likely to fear than to explore whereas in the learning phase, both objects have the same scare effect.

This type of behavioral research pertaining to zebrafish is new territory. At this point it is calling for new ways of testing and scoring data. Recently, we finished a new set of tests on the fish which we believe completely takes away the role aversiveness had in the previous tests. In my next blog post I will discuss this new test along with another innovative idea we plan to use in the near future based on a variation of Edward Levin’s research (http://www.ncbi.nlm.nih.gov/books/NBK5216/).

Please leave questions below if anything I mentioned raises them.