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Unformatted text preview: 12/7/07 Lecture 44 ASUC Lecture Notes Online (formerly Black Lightning) is the only authorized note-taking service at UC Berkeley. Please do not share, copy or illegally distribute these notes. Our non-profit, student-run program depends on your individual subscription for its continued existence. These notes are copyrighted by the University of California and are for your personal use only. ANNOUNCEMENTS : Final exam: Dec 19, 8-11am Blue Gym (RSF) DSP rooms: 2032 VLSB Office hours next week: yes Review session: Sat, Dec 15, 9-11am Location TBA. What I'm trying to present in the book are basic principles using genetic analysis. If you're wondering about things like Gal4/Gal80, try to understand it like the lac operon example, as an example of gene regulation. REVIEW You'll see today how important understanding the processes for Drosophila is for mammalian development. We covered maternal genes in the mother that are important for embryonic development. Then there are zygotic genes, or genes in the embryo necessary for development. Then we talked about how this whole system of development was a hierarchy. We talked about Gap genes, the first genes regulated in the embryo by maternal effect genes and by each other. Then we talked about the next level: pair-rule genes. We're going down in "size". On the first level we have maternal effect genes, then we start narrowing down to specific areas of the embryo. So there are Gap genes in the middle chunk of the embryo, that is, so Gap gene mutants are missing a big chunk in the middle. So there's a hierarchy of regulation and each level defines more and more the precise areas of the embryo. The pair-rule genes separate in 7 bands that cover all bands in the embryo. Now we're looking at specific regions of the pair-rule regions. And lastly, we need to consider the segment polarity genes and then we'll consider these questions. SEGMENTATION HIERARCHY Here are the Gap genes and the area they are influencing. Here are the areas that the pair-rule genes are influencing. Finally, the segment polarity genes are expressed in stripes that correspond to 14 segments of embryo. SEGMENT POLARITY GENES This is the last level of zygotic effect regulation. Segment polarity genes are expressed in stripes and they are repeated in each of the 14 segments of embryo. Regulation of segment polarity gene expression is started off by transcription factors encoded by pair- rule genes. This step of development is the interface between nuclei that cellularize. It's not just a gradient of transcription factors that will affect gene expression, but now you'll start having interaction between cells in the form of signal transduction in order to maintain the pattern of development that's been set up....
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- Fall '08