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Michael Goldrich (Molecular and Cell Biology and Public Health major)
"Targeted Genome Modification Using Zinc Finger Nucleases"
Sponsor: Sharon Amacher, Molecular and Cell Biology: Genetics, Genomics and Development
Project Description
Genetic work with model organisms, such as fruit flies, mice, and zebrafish, has provided invaluable insights into the mechanisms behind human disease and development. One tool for creating these models is direct modification of the genome. Michael is optimizing the use of reagents, called zinc finger nucleases (ZFNs), in order to create specific and targeted modifications in the DNA sequence of a very genetically tractable system, the zebrafish. Using ZFNs, genes can possibly be directly targeted to express desired proteins, incorporate molecular tags, or can even be repaired by a corrected template. He will develop assays to quantify ZFN-mediated targeting and optimize conditions to improve targeting efficiency, with the goal of making this technology broadly accessible to and widely used within the scientific community.
Scholar's Photo
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Michael adjusting the microinjector that he uses to inject zebrafish embryos at the one-celled stage. |
Scholar's Journal
The Haas program allowed me to become a full-time scientist for the summer of 2009. I have worked in the Amacher lab every semester since I began college at UC Berkeley three years ago, but it all seems like a sweet (albeit long) prelude to the intellectual and personal growth that I underwent this past summer. I was able to focus on nothing but science. That experience itself was exhilarating. I didn’t have to forgo an experiment due to a class stuck in the middle of my day or a midterm the next week. I could design, work on, and complete experiments, seeing them all the way through in a matter of days rather than weeks.
I came to love just “talking science.” Passing ideas past my mentors and colleagues turned from a dreaded encounter to an enjoyable dialogue. I could actually hold my own in the world of developmental genetics. I was able to introduce my own experiments, explain an unexpected result, and discuss the future of my project with an understanding and raw excitement that I previously had only had passing tastes of.
Every week I came bounding into the lab, hopeful to see dark spots littering the eyes of my previously injected zebrafish embryos. Time after time I was let down to be greeted by hundreds of unpigmented pairs of eyes. However, I was still encouraged by one of my earlier results: a lone pigment clone (or patch of identical cells) in the eye of one of my many embryos. Hopefully, that result showed that although homology-directed repair (the process behind those spotted eyes) is not favored, it is biologically possible.
I was also encouraged by the bevy of tricks that I was able to apply to my problem, in hopes of pushing the mechanisms of DNA double strand break repair in my favor. When zinc finger nucleases and a wild-type donor weren’t enough, I was able to add new elements to the injection cocktail. First, I tried adding in a RecQ dominant negative construct, which was suppressing a suppressor, or in other words a promoter, of homology-directed repair. Those colorless eyes still stared back at me, almost mockingly. To no apparent avail, I also used a ligaseIV dominant negative construct, which also should bias the DNA repair pathway towards my desired result. At least with this experiment, even if I didn’t get my pigmented islands of retinal cells, I still saw beautiful red fluorescence whenever there was a successfully injected embryo due to a fluorescent red protein that was translated from the injected RNA. I think the fact that I am injecting properly is an important victory because it’s the little confirmations and successes in science that keep me going. Sometimes I take a small step back to realize how the procedures and experiments that have sometimes become so mundane to me are actually quite miraculous. And now, I have a living organism that is fluorescing red and possibly carrying a rescued copy of a mutation that I could have fixed in its germline. That is yet to be tested, but the promise and potential of this project still keeps me captivated.
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