Courtship + Mating in Drosophila Flashcards
What are the 4 stages of courtship?
Orientation.
Wing Extension.
Licking.
Copulation.
What are the (4) measurable courtship parameters?
Total time courting during observation period.
Latency to initiate courtship.
Latency to copulation.
Courtship steps performed (order, latency and total duration).
What are the courtship signals / senses?
(and how were they discovered)?
Visual
(measure under red light - removes visual stimuli)
Olfactory
(measure using mutant flies lacking olfaction / cut off antenni)
Auditory
(measure using mutant flies lacking audition)
Gustatory
(measure using mutants lacking gustation)
Which senses are used in which stages of courtship?
Orientation = Olfaction + Vision
Tapping = Taste (-ve signal = sex peptide = female unreceptive)
Wing Vibration = Olfaction + Audition
Licking = Audition + Taste
What is the courtship index (CI)?
= time spent courting ÷ observation period
What are the specific class of visual projection neurons dedicated to courtship? (+what do they do?)
= LC10 visual projection neurons
= required to track fly-sized object
= sense moving visual objects
= activation of LC10 elicits courtship that is enhanced by courtship arousal
What are the chemosensory signals (pheromones) in male and female fruit flies?
Male:
= secrete cVA, 7-T, 7-P on surface cuticle
= are attractive to females (+ young males)
= inhibit / elicit aggression in other males
Female:
= secrete 7,11-HD + 7,11-D on surface cuticle
= attractive to males
= allow males to identify females of same species
What are the auditory signals involved in courtship?
= Male love song
= allows females to recognise males (species-specific)
= makes female receptive to copulation
= female ‘hears’ song through antennae
What are some structural elements of acoustic communication?
Antenna = a2 + a3
Also Arista = base has Johnstons’s organ = increases speed to become receptive
Transduction module = responds to sound waves, opens channel, action potential
AMMC = antennal mechanosensory + motor centre = has different zones, neurons project here
What are the genes involved in controlling male and female behaviours?
Male = fruitless (fru)
= default splicing
Female = fruitless (fru) + doublesex (dsx)
= regulated splicing
= male and female versions of each
How do genetic mutants behave? (phenotypes?)
dsx null mutant males
= normal except one part of courtship song
male dsx in females
= transformed into males but did not court
fru null mutant males
= phenotypically male but no courtship
less severe fru mutant alleles
= males with defects in different stages of courtship
Where is FRU male-specific protein expressed?
The CNS
Sensory neurons
(also in peripheral neurons)
How to neuroanatomically dissect courtship behaviour? (experimentation)
- Genetically modify brain region / cell type
- Measure effect on behaviour
= change seen = region involved in behaviour
= no change seen = region not involved in behaviour - Visualise / identify the modified cells / neurons
- Repeat with many discrete and overlapping patterns of brain modification to identify regions / cells involved in behaviour
Examples of neuroanatomical experiments done?
- Male / female mosaics (gynandropmorphs)
= used to identify broad sexually dimorphic regions of CNS involved in male courtship - GAL4/UAS system
= used to refine location of sexually dimorphic brain circuitry using UAS-traF driven by GAL4 lines with distinct patterns of expression in CNS - UAS transgenes
(UAS-shits, UAS-eag(delta), UAS-Ttx)
= used to alter activity of neurons
= to identify non-sexually dimorphic circuitry
Proposed model for perception / integration of orosensory (a) + taste (b) information in male CNS?
Proposed model for controlling initiation of male courtship / male song in CNS
Proposed model for sex peptide signal in female?
= to regulate post mating response
