Drosophila melanogaster

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Drosophila melanogaster
Source Zdenék Berger
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Mating
adult
Egg-laying
Life Cycle (10 days)
pupa
Embryo
larva
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Drosophila natural history

• Originated in Africa
• Probably spread by human activity
• Now found most places where we live
• Likes compost, rotting fruit, yeast
• Some features conserved, others a reflection of
  its life strategy
• Harmless (mostly)
• Most lab strains derived from isolates collected
  before 1940s
• Strains collected subsequently have P
  transposable elements and cant easily be used

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Model Organisms - a trainspotters guide
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Where our pet flies live Mice -
75c/day 150k/yr Flies 20k/yr (consumables
and labour) Cant be stored frozen -(
Source John Roote
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What are flies useful for?
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Fly pushing
Early 1900s - Drosophila contributes to our
understanding of heredity Mid 1900s - Grows in
popularity among developmental biologists
Homozygous lethal mutations can be kept
indefinitely as heterozygous balanced
stocks 1970s - 1980s - Molecular biology,
cloning of Hsp, Hox 1970s - 1980s - Large
screens for developmental mutants 1982 -
Transformation by injection of marked P
transposable element into syncytial embryos
transgenic flies identified by marker in F1 1988
- Easy mobilisation of P made possible by stable
transposase-producing strains
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Recent articles from PubMed
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C.J. OKane (2003). Seminars in Cell and
Developmental Biology 143-10. Source Claude
Everaerts
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Whats different?

• More gene redundancy in humans mammals
• Some organisation of tissues and organs
• Cardiovascular system
• Acquired immunity (antibody response)
• Were studying them, instead of them studying us

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(No Transcript)
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Insertional mutagenesis many ways to kill a gene
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Fly Gene Disruption Projects

• Based on transposable element insertion
• Allows further local mutagenesis
• Non-directed - like Venters sequencing strategy
• Not random
• 15000 target genes
• include 4000 vital genes
• Requires 1 insertion per 8 kb
• Coverage perhaps 25 of that, more on their way
  into public domain

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FlyBasewww.flybase.org
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Other ways to make mutants

• EMS - still has its attractions
• Targeted knockouts for reverse genetics
• Imprecise excisions for reverse genetics
• RNAi for reverse or forward genetics
• Deletion kits in defined backgrounds
• Ask a fellow flypusher

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Getting round early lethality

• GAL4 x UAS-X for targeted expressionCan be
  used for regulated RNAi expression

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GAL4 enhancer traps
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Getting round early lethality

• GAL4 x UAS-X for targeted expression
• Enhancer/suppressor screens

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Identifying genes in receptor tyrosine kinase
signalling - screening for enhancers of
sevenlessts
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Getting round early lethality

• GAL4 x UAS-X for targeted expression
• Enhancer/suppressor screens
• Mitotic clones (using FLP recombinase)

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Mutant screens using mitotic clones
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Getting round early lethality

• GAL4 x UAS-X for targeted expression
• Enhancer/suppressor screens
• Mitotic clones (using FLP recombinase)
• Temperature-sensitive point mutations
• RNAi screens in cultured cells

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Shared biology - shared diseases

• Cancer
• Ageing
• Neurodegeneration
• Infectious disease
• Models for disease vectors
• Behaviour

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Flies and your disease

• Do flies have disease-gene homologs?
• Do flies have basic cellular processes related to
  the disease?
• Be nice to a friendly fly geneticist

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The future?

• More insertions
• UAS-RNAi collections
• SNPs, better mapping of point mutations
• Temperature-sensitive alleles for cell biology
• Screens take more work in flies than in worms
• Some things only possible in flies and not worms
  - physiology, some development, some cell
  biology
• Hopping in takes about 20k investment, or a
  friendly fly lab to drop in on