Drosophila behaviour Flashcards Preview

Laboratory Animal Science > Drosophila behaviour > Flashcards

Flashcards in Drosophila behaviour Deck (31):
1

Name advantages of the use of Drosophila as an animal model

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

2

What are reasons to be aggressive?

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

3

How can p-elements be used in mutagenesis?

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

4

Drosophila life cycle

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

5

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

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

6

Lenght of Drosophile life cycle

10-12 days at RT

7

mutagenic effect of p-elements

DNA insertions (mostly hypomorphic)

8

P-element

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

9

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

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

10

Why is drosophila a valuable model system?

  • - 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

11

GAL4/UAS binary transgenic expression system

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

12

How to make a transgenic fly using transposons

  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

13

advantage of P-elements

  • fast gene identification
  • flexible scale

14

Features shared by Drosophila and other animals

  • - obligate diploid -
  • sexually dimorphic gametes -
  • some genetic redundancy

15

What are transposons?

  • 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

16

How many chromosomes does D. melanogaster have?

4

17

disadvantages of P-elements

  • no saturation
  • non-random (hotspots)

18

Three types of transposable genetic elements

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

19

Name behaviours of male flies

ignore

mate

attack

flee

20

How do males behave when the external cue is female?

  • virgin --> mate
  • mated --> ignore

21

How do males behave when the external cue is male?

  • dominant --> flee
  • submissive --> attack or ignore
  • unknown --> attack

22

How do males behave when the internal cue is satiated?

  • female --> mate
  • male --> ignore or attack

23

How do males behave when the internal cue is hungry?

  • female --> ignore
  • male --> attack

24

Name some molecules that affect aggression in flies

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

25

What does CREB regulate in flies?

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

it mediates the starvation genotype

26

Which GTPase signals in the cVA pathway?

Rac2

27

Why do males put cVA on females?

  • 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

When is Rac2 active/inactive?

  • active: bound GTP
  • inactive: bound GDP

29

Name characteristics of Rac2 mutants

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

30

Or67d mutants

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

31

How does diet influence the behaviour of flies?

  • 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