Drosophila behaviour Flashcards

1
Q

Name advantages of the use of Drosophila as an animal model

A
  • short generation time
  • easy to maintain
  • 4 large chromosomes
  • cheap to maintain
  • easily identifiable markers (mutant phenotypes)
  • transposons
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2
Q

What are reasons to be aggressive?

A
  • access to mates
  • access to food
  • access to territory to gain mates and foot
  • maintain social hierarchy
  • defence against predation
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3
Q

How can p-elements be used in mutagenesis?

A

When they excise from the genome, they sometimes remove pieces of the DNA, making a mutant gene. In about 90% perfect excision, in 10% they take out more. The big advantage of that: control and mutant are genetically identic; good to reduce background noise

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4
Q

Drosophila life cycle

A

egg/embryo - 1st instar larva - 2nd instar larva - 3rd instar larva - prepupa - pupa - adult

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5
Q

Why is Drosophila a good model for the study of human disease?

A

1) Rapid construction of transgenic models of human disease
2) Well established easy systems to drive kd/ko our over expression of gene expression in tissue or temporal specific patterns
3) able to rapidly identify modifier/bypass gene pathways via genetic screens for enhancers or suppressors of phenotypes
4) easy to culture cell lines - very-easy to dsRNA treat genes of interest
5) rapid determination of the molecular basis of disease mechanisms
6) rapid forward genetics - isolate mutants through transposons or chemical mutagenesis

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6
Q

Lenght of Drosophile life cycle

A

10-12 days at RT

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7
Q

mutagenic effect of p-elements

A

DNA insertions (mostly hypomorphic)

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8
Q

P-element

A

a DNA-dependent transposon (no RNA intermediate; genomic DNA at original insertion site) flanked by inverted repeats (IRs)

transposase will cut out the transposon and insert it to another place in the genome

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9
Q

Using GAL4/UAS to get rid of a gene/ knock down a gene

A

Insert an inverted repeat of your targeted gene after UAS –> when it is transcribed, it will form dsRNA –> this will lead to RNAi –> inhibition of protein expression, because mRNA of the targeted gene is destroyed

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10
Q

Why is drosophila a valuable model system?

A
    • It’s an animal; can be used to study development, physiology, and behaviour -
  • over 100 years of genetics -
  • 70% of human “disease” genes have an homologue in Drosophila
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11
Q

GAL4/UAS binary transgenic expression system

A

most used nowadays

  1. one fly with tissue specific promoter followed by GAL4 in p-element (i.e. flanked by IR) -
  2. one fly with UAS (upstream activating sequence that is the GAL4 target) followed by transgene in p-element -
  3. mate them -
  4. the progeny will express the transgene in cells also expressing GAL4 –> GAL4 expression activates UAS and transgene is turned on
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12
Q

How to make a transgenic fly using transposons

A
  1. -Add a plasmid carrying the transposon/detective p-element and a donor plasmid with your desired transgene and a marker flanked by IR into D. embryo before the germline forms -
  2. Hope that your transgene wil jump into the fly genome, mediated by p-element -
  3. screen/select for marker -
  4. at the excision site, either repair using a sister choromatid/homologous chromosome containing a P-element –> transposon remains in original position OR repair of gap using a homologous chromosome lacking a P element –> transposon no longer at original position
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13
Q

advantage of P-elements

A
  • fast gene identification
  • flexible scale
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14
Q

Features shared by Drosophila and other animals

A
    • obligate diploid -
  • sexually dimorphic gametes -
  • some genetic redundancy
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15
Q

What are transposons?

A
  • Small pieces of DNA that can move from one site in the genome to another -
  • All organisms have them (about 45% of our genome: transposon remnants) -
  • jumping genes, selfish DNA -
  • mechanism for evolutionary change
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16
Q

How many chromosomes does D. melanogaster have?

A

4

17
Q

disadvantages of P-elements

A
  • no saturation
  • non-random (hotspots)
18
Q

Three types of transposable genetic elements

A
    • DNA-dependent (prokaryotes & eukaryotes; DNA intermediates) -
  • retroviruses (eukaryotes only, RNA intermediates) -
  • retrotransposons (eukaryotes only, RNA intermediates)
19
Q

Name behaviours of male flies

A

ignore

mate

attack

flee

20
Q

How do males behave when the external cue is female?

A
  • virgin –> mate
  • mated –> ignore
21
Q

How do males behave when the external cue is male?

A
  • dominant –> flee
  • submissive –> attack or ignore
  • unknown –> attack
22
Q

How do males behave when the internal cue is satiated?

A
  • female –> mate
  • male –> ignore or attack
23
Q

How do males behave when the internal cue is hungry?

A
  • female –> ignore
  • male –> attack
24
Q

Name some molecules that affect aggression in flies

A
  • ocotopamine (noradrenaline)
  • dopamine
  • serotonin
  • NPF (NPY)
  • 11 cis-vaccenyl acetate (cVA)
25
Q

What does CREB regulate in flies?

A
  • inhibits mating
  • induces aggression
  • induces lipid storage
  • induces feeding

it mediates the starvation genotype

26
Q

Which GTPase signals in the cVA pathway?

A

Rac2

27
Q

Why do males put cVA on females?

A
  • makes males more aggressive –> they are not interested in mating anymore
  • when it builds up, the males will leave, so the females end up having all the food they need for the offspring
28
Q

When is Rac2 active/inactive?

A
  • active: bound GTP
  • inactive: bound GDP
29
Q

Name characteristics of Rac2 mutants

A
  • hyperactive
  • mating behaviour defect (they want to mate NOW)
  • not aggressive
  • lean phenotype
  • lower lipid content
30
Q

Or67d mutants

A
  • upstream of Rac2
  • lipid storage defect
  • more susceptible to infection as they age
31
Q

How does diet influence the behaviour of flies?

A
  • high protein/high sugar –> kills them very fast
  • high protein –> less aggressive
  • high sugar –> less low intensity fighting
  • low sugar –> active
  • low sugar –> more interaction
  • low protein –> much more aggressive
  • Atkins diet –> heart attack