T ask 3: Zebrafish forward genetic screens [8 marks] Genome-wide genetic scr...
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Task 3: Zebrafish forward genetic screens [8 marks]
Genome-wide genetic screens for phenotypes can identify new gene candidates and reveal novel mechanistic pathways that control development of tissues and organs. So-called “forward genetics screens” employ ENU-induced mutagenesis to produce random mutations in the genome. Phenotypes are observed and through breeding and mapping the affected gene can be identified. Two large scale ENU-mutagenesis zebrafish genetic screens performed in the mid-1990s produced thousands of mutations affecting development and organogenesis.
One of the first classes of mutants that were detected from these screens were the pigment mutants. Today you will examine the mutants nacre, roy orbison and casper, compared to a wild type adult fish. Which one is wild type?Question 3: Zebrafish pigment mutants.
3a) Take a photograph of the wild type fish to compare your mutants. (1 mark)
3b) Take a photograph of the nacre mutant zebrafish and identify the defect/s compared to the wild type fish. (2 marks; one mark for the image and one for the labelling of defect.)
3c) Take a photograph of the casper mutant zebrafish and identify the defect/s compared to wild type fish. (3 marks; one mark for each correct drawing and correct labelling of defects - note, plural!)
3d) Take a photograph of the leopard mutant zebrafish and identify the defect/s compared to wild type fish. ( 2 marks; one mark for the image and one for labelling of defect.)
Combine your images for Q3 into a single figure together with labels indicating each zebrafish (ppt is a good place to do this). Upload the (as a jpeg or pdf) to Moodle. Please ensure that you clearly label which type of mutant/wild type is which and identify the defect(s) in each mutant.