the eye of the embryo. With repeated trials, you observe that any embryo marked in that same starting cell always gives rise to a labeled eye, and so you conclude this starting cell to be ‘ the eye progenitor ’. 3. You performed this fate mapping study by injecting the eye progenitor cell with a fluorescent dye. What is one potential criticism of your fate map data? 4. From these data, can you infer whether the eye progenitor in the early embryo was either specified or determined to become an eye? In your answer, provide clear reasoning as to whether the term specified or determined could or could not be used to describe the eye progenitor. You surgically remove the eye progenitor at the early cleavage stage, expecting that an eye-less embryo will develop. However, you are surprised to find that all embryos with this surgery develop a normal pair of eyes. 5. What does this experiment suggest about the mechanism of development that is operative with regard to the eye? In your answer, clearly define the difference between mosaic and regulative mechanisms of development. Next, to learn more about the eye progenitor, you make a cDNA library from the embryo so that you can search for genes transcripts that are unique to the eye progenitor. You perform a whole mount in situ hybridization screen using the cDNA collection and find several transcripts that are specific to just the eye progenitor. One cDNA is particularly intriguing to you because it looks like a gene that has not been discovered in other species yet, so you decide to study it further. 6. What technology could you use to test if your chosen eye progenitor gene is necessary for eye formation? Assume that all technologies that work in non-mammalian models can be successfully performed in your critter. In your answer, clearly state one possible phenotype you would predict to see if your gene is necessary, and one possible phenotype if your gene is not necessary.
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