Cait, Entry #2, Massacring Fish

This past week I learned how to fin clip fish. This procedure is done by using a razor blade in order to remove the tail from the back of the fish. Keys to fin clipping are to make sure the fish is fully anesthetized (using a solution of a chemical called Tricane which the fish swim in until they fall asleep), because if they are not completely knocked out they will squirm and jump as you attempt the first part of the cut. I learned this the hard way when my first fish began to wriggle after I had only chopped half of his tail. Another key to fin clipping, is to make sure the fish do not die, either by sleeping for too long in the Tricane or by chopping to far up the tail to where you cause the fish to bleed out. I felt morally wrong chopping of the tails of fish who had done no wrong to me, but I learned that a zebra-fish tail has the ability to grow back, and many compare fin clipping to clipping your nails. Also, the results of fin clipping provide a great amount of information in the project my grad student and I are working on.

These fin clips contain DNA from the adult fish. We extracted the DNA by placing the fins in ethanol and then using an enzyme called proteinase to break down the fins. After we extracted the DNA, we performed an HRM analysis on it. HRM stands for High Melt Resolution, and it works by having two different fluorescent binding proteins. One protein when bound to Wild Type DNA shines red, while the other protein binds to mutant DNA and shines green. When the fish are Heterozygous a mixture of the proteins bind causing a fluorescent yellow. The HRM machine looks to see when these fluorescence tags stop shining, and that allows the machine to identify when the DNA has begun to denature. These results allow us to figure out which fish are carrying for mutant alleles.

Another skill I learned in the lab this week was that zebra-fish must die twice in order for it to be humane. Fish are killed for many reasons, they are sick, taking up too much space, or are too old. Ben and I had to clear out tank space in order to raise new fish and this caused me to become very familiar with the fish death method. The first death is done by placing the fish in ice cold water, causing them to freeze. The second death is then placing those fish into bags and putting them in the freezer to freeze more.

Death #1Death #2