1. Drosophila melanogaster
Source: Zdenék Berger

2. Mating
adult
Egg-laying
Life Cycle
(10 days)
pupa
Embryo
larva

3. 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 1940’s
Strains collected subsequently have P transposable elements and can’t easily be used

4. Model Organisms - a trainspotter’s guide
E. coli
Yeast
Worm
Fly
Mouse
Human
Genome (Mb)
4.6
150
3000
100 12
# Genes
4000
6000
19000
15000
30000?
# Neurons
(1)
302 10 5 11

5. Where our pet flies live…
Mice - 75c/day
150k$/yr
Flies ~ 20k$/yr
(consumables and labour)
Can’t be stored frozen :-(
Source: John Roote

6. What are flies useful for?

7. Fly pushing
Early 1900’s - Drosophila contributes to our understanding of heredity
Mid 1900’s - Grows in popularity among developmental biologists
Homozygous lethal mutations can be kept indefinitely as heterozygous balanced stocks
1970’s ’s - Molecular biology, cloning of Hsp, Hox
1970’s ’s - Large screens for developmental mutants
Transformation by injection of marked P transposable element into syncytial embryos; transgenic flies identified by marker in F1
Easy mobilisation of P made possible by stable transposase-producing strains

8. Recent articles from PubMed

9. C.J. O’Kane (2003). Seminars in Cell and Developmental Biology 14:3-10. Source: Claude Everaerts

10. What’s different? More gene redundancy in humans & mammals
Some organisation of tissues and organs
Cardiovascular system
Acquired immunity (antibody response)
We’re studying them, instead of them studying us

12. Insertional mutagenesis: many ways to kill a gene…

13. Fly Gene Disruption Projects
Based on transposable element insertion
Allows further local mutagenesis
Non-directed - like Venter’s sequencing strategy
Not random
~ target genes
include ~ 4000 vital genes
Requires ~ 1 insertion per 8 kb
Coverage perhaps 25% of that, more on their way into public domain

14. FlyBase www.flybase.org

15. 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

16. Getting round early lethality
GAL4 x UAS-X for targeted expression Can be used for regulated RNAi expression

17. GAL4 enhancer traps

18. Getting round early lethality
GAL4 x UAS-X for targeted expression
Enhancer/suppressor screens

19. Identifying genes in receptor tyrosine kinase signalling - screening for enhancers of sevenlessts

20. Getting round early lethality
GAL4 x UAS-X for targeted expression
Enhancer/suppressor screens
Mitotic clones (using FLP recombinase)

21. Mutant screens using mitotic clones

22. 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

23. Shared biology - shared diseases
Cancer
Ageing
Neurodegeneration
Infectious disease
Models for disease vectors
Behaviour

24. 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

25. 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