MCDB Corefly development

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MCDB Core-fly development patterning and genetic
techniques
Bob Boswell Lecture 1 4-24-07
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How is body plan determined?
(Wieschaus Nusslein-Volhard 1980s)
fertilized egg
head
tail
older embryo
Find mutants that cannot make correct body
plan. -gtmutants in genes that normally determine
body plan. segmentation genes
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T1
A1 2 3 4
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2 3
larva
T1 2 3 A1 2 3 4 5 6 7 8
adult
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gap genes
Data Kr is present in the middle region of
embryos Kr mutants lack the middle
region Conclusion Kr is needed to specify the
middle region
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Gap mutants
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gap gene proteins
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pair rule genes
Data ftz is transcribed in every other
segment ftz mutants lack every other
segment Conclusionftz specifies the identity of
alternate segments
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Distribution of pair rule proteins
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segment polarity genes
Data En is present in the posterior half of
each segment en mutants lack the posterior half
of each segment Conclusion en specifies the
posterior half of each segment
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Cascade of embryonic gene expression
(transcription) gap-gt pair-rule -gt segment
polarity
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P-elements
Transposase
1. Naturally occurring transposable elements 2.
Encode transposase and thus catalyze their own
transposition 3. Insertional mutagenesis 5
end of genes Preference for specific sequence
motifs Hot spots
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Utility of P-elements

• Construction of transgenic flies
• 2. Enhancer trap (identification of genes based
• on pattern of expression)
• 3. Generation of additional mutations
• 4. Generation of deletions with defined endpoints

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Gal4 UAS System
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Genetic Mosaics
Mosaic the presence within one individual of
cells differing with respect to their genotype
FRT-Mediated Mitotic Recombination Flipase
recombination target (FRT) FLP (Flipase)
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DAPI
GFP
Cut
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Flipout Method