Drosophila Pheremones Flashcards
(12 cards)
Describe the pheremone profile of drosophila flies and simulans flies?
cVA only volatile pheremone.
Males - cocktail of 7-T and 7-P (cis7-tricosene and cis7-pentacosene)
Females - 7,11HD and 7,11ND (cis cis7 heptacosadiene and cis cis7 nonacosadiene)
Simulans males and female have same profile as melanogaster male but varying proportions of each.
Nerd mutant has half the normal titre of 7-T and will court but is rejected.
How does the proportion of male and female pheremones influence courtship behaviour?
Use GAL4 UAS-tra to show that an increase in male pheremones decreases courting from males and an increase in female pheremones increases courting from males.
What do each pheremone do in the courtship display?
7,11ND and 7,11HD both determine the wing vibration whilst 9P decides copulation. 5-T prevents tapping whilst 7T, 7P and 5,9HD prevent vibrations.
Interestingly the proportion of 7,11HD varies geographically and can be seen where flies came over from africa to the carribean in the slave trade due to lower titres.
How can we alter pheremone levels at different times and places and what does this show us?
Use hsp-GAL4 - UAS-tra. Sensetive period is late pupal early adult phase. If tra is over expressed in females is removes all pheremones.
These females are still courted, if they’re dead they are still courted but if they are killed, washed and then using the run off to re-coat them they are no longer courted.
How does washing in simulans, sechellia or mauritiania change the courtship of pheremone-less females by normal males?
Washing in simulans or mauritiania results in no courting - these are both monomorphic for male DM pheremones.
Washing in sechellia = courtship. DM and secellia are dimorphic for their pheromones.
So 7,11HD and 7,11ND both prevent interspecific courtship.
What are oenocytes and how can we use them to study drosophila pheremones genetically?
Oenocytes produce pheremones. Desaturase enzyme is involved in the production of all pheremones.
Express Gal4 under Desat promoter and we can visualise where all the oenocytes are and also kill off all the oenocytes. This creates a pheremoneless (except cVA) female.
How do Oe- males and females court?
Oe- males court slowly and Oe- females are courted faster. So Male pheromones act as an attractant to females and female pheromones repress courting in males slightly.
Also Oe- males are courted by other males. 7T is used to repress homosezual courtship.
How does Oe- DM females courted by other species males?
Oe- DM female courted by all males. So Female specific (7,11HD) pheromones act as inter-specific repressors of courtship. If you corss wash an Oe- female DM with the female pheremones of another species, that species male will then court it. e.g. 7-T for simulans and 7,11HD for melanogaster.
How did melanogaster males exploit a male bias to increase their mate guarding?
CH503 - pheremones produced by the male ejaculatory bulb and rubbed off onto the female during copulation. - makes her unattractive to other males.
DM only fly with this but it has a more potent effect when rubbed onto other species females.
How are Gr68 and Gr32 used to detect pheremones and stimulate the right courtship?
Gr68 found on male legs and labial palps - also expressed in tra- pseudo-males. When mutated only effects male female courtship so must be involved in detecting female pheromones.
Gr32 co-localises to the same locations as Gr68 but only effects male-male courtship so must be detecting male pheromones. Originally thought to not have any effect on male-female courtship but was later shown that there is more SWEI in mutants.
What other genes can effect SWEI?
Gr66 phenocopies Gr32 and is co expressed. Odp57 d and e are the same except only Odp57d causes SWEI.
Gr32 neurons run to the SOG and then to the mAL - sex specific region fru-m. If we use shibire and MARC we can kill off these neurons which increases SWEI.
Model: Gr32 detects female pheremones - inputs from tarsi to SOG and this inhibits the ispilateral mAL but stimulate the contralateral mAL. This results in one wing extending. When the circuit is broken = SWEI.
How do the PPK23 and PPK29 genes influence courtship?
PPK23 is a taste receptor and is co expressed with fru-m giving it sex specific neurons. PPK29 is co expressed with PPK23 but is not sex specific.
PPK23 mutants court other males whilst PPK29 mutants don’t. Both mutants decrease male-female courtship.
Both PPK mutants don’t respond to male pheromones (PPK29 does still a little) indicating that normally these taste receptors detect male pheromones and prevent courtship. Also both mutants don’t respond to female pheromones, again indicating that normally they respond to female pheremones to stimulate courtship.
We can use Ca imaging to show their neurons responding in a sex specific manner to male and female pheromones in a specific manner. PPKs are contact gustatory chemo-receptors.
