Courtship Circuits
What do vAB3 neurons do in the courtship circuit?
Relay excitatory pheromone signals to P1 neurons
How did optogenetics help prove the sufficiency of P1 neurons for courtship?
Activating P1 neurons with light triggered courtship behavior.
What is the main pheromone that differentiates courtship behaviors in D. melanogaster and D. simulans?
7,11-heptacosadiene
Which receptor detects 7-tricosene (pheromone from D. Simulans)
Gr32a
What happens to D. simulans courtship behavior when mAL neurons are severed?
Courtship increases due to reduced inhibition of P1 neurons.
What is GCaMP6s, and what does it measure?
A calcium indicator used to measure neuronal activity.
True or False: vAB3 and mAL pathways are similarly activated by the 7,11-HD pheromone, so the difference in suppression versus promotion of courtship may be due to P1 excitation?
True
How many years ago did D. melanogaster and D. simulans diverge?
Why does activation of P1 neurons result in different behaviors in D. melanogaster and D. simulans?
Differences in excitatory/inhibitory input to P1 neurons drive species-specific behaviors.
What does iontophoresis of acetylcholine do?
Delivers acetylcholine to dendrites to mimic natural activation
What is the neural circuit that makes D. simulans males avoid females with 7,11-HD?
Inhibition from mAL neurons overcomes vAB3 excitation and suppresses courtship.
What technique was used to map the projection patterns of P1 neurons?
GFP labeling
What type of neuron is responsible for detecting pheromones like 7,11-HD?
ppk23+ neurons
How did the researchers use the GFP and Gal4 system to demonstrate the conservation of Fru+ neurons between D. melanogaster and D. simulans?
They inserted GFP or Gal4 into the Fru gene locus to map neuron projections and showed that Fru+ neurons had similar distributions and projection patterns in both species
What is conserved between D. melanogaster and D. simulans in their courtship circuits?
The anatomy and function of vAB3, mAL, and P1 neurons.
Imagine ppk23+ neurons were knocked out in both D. melanogaster and D. simulans. How would each species respond to 7,11-HD, and what behavioral differences would still remain?
Possible response: Neither species would detect 7,11-HD, eliminating species-specific responses to this pheromone. However, D. melanogaster males might still exhibit generalized courtship due to other cues, while D. simulans males might not initiate courtship as easily.
Draw the Fru+ circuit that proces 7,11-Hd (include 7,11-HD input, ppk23, vAB3, mAL, and P1)
7,11-HD --> ppk23 --> vAB3 --> P1 & mAL --| P1
To generate mutant alleles of ppk23 and Gr32a, the researchers designed sgRNAs targeting three regions spanning 200 bp of the first exon for each gene. These sgRNAs were combined into a single cocktail and injected into...
D. simulans eggs
Hypothesize: if 7,11-HD detection is conserved, why might D. simulans males not develop a "neutral" response instead of active repulsion?
possible response: Active repulsion may provide an evolutionary advantage by ensuring males focus only on conspecific females, increasing mating efficiency and reproductive success.
Come up with a future study and explain a few techniques you would use!
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