3. Courtship in Drosophila

Question 1

what courtship parameters can we study? (4)

Answer 1

• total time courting during the observation period
• latency to initiate courtship
• latency to copulate
• order of courtship steps

Question 2

what does the female receive that allows them to make a decision as to whether they want to copulate

Answer 2

volatile pheromones and vibrations

Question 3

what type of receptor is the sex peptide receptor

Answer 3

a GPCR

Question 4

what does sex peptide contain

Answer 4

two anti-aphrodisiac pheromones
cVa
7-T

Question 5

how does sex peptide regulate female receptivity

Answer 5

modulates the properties of fruitless neurons via a monophosphate signalling pathway

Question 6

what is sex peptide released alongside

Answer 6

the sperm

Question 7

what is the action of sex peptide

Answer 7

sex peptide receptors in the uterus which activate uterine neurons that project to the abdominal ganglia and SOG. this pathway alters the pheromones and behaviours the female produces to warn other males that the y do not wish to mate.

Question 8

describe the order of the courtship ritual

Answer 8

1. orientation
2. wing extension
3. licking
4. copulation

• repetitive process that continues until the female becomes receptive.

Question 9

what neuron is responsible for the courtship song production in males

Answer 9

the mesothoracic ganglion

Question 10

what happens when fragments of the D. simulans period gene are expressed in D. melanogaster?

Answer 10

D. melanogaster produces the species specific song of D. simulans

Question 11

the courtship song is species specific, what gene controls it?

Answer 11

period gene

Question 12

where is the SOG located

Answer 12

in the protocerebrum

Question 13

describe the process of licking in the courtship ritual

Answer 13

gustatory receptor neurons on the foreleg tarsi and mouthparts detect non-volatile pheromones which enter the sensilla via single cuticle pore.

the female pheromone info is then relayed via a single axon to the SOG, and the male decides whether or not to act

Question 14

what wing produces a series of species-specific vibrations = courtship song

Answer 14

the ipsilateral wing

Question 15

a specific class of visual projection neurons are dedicated to courtship, what are these called?

Answer 15

LC10 visual projection neurons

Question 16

what are LC10 visual projection neurons required for

Answer 16

tracking a fly size object

Question 17

where do flies secrete pheremones?
what does this allow?

Answer 17

the cuticle
allows species recognition

Question 18

name a female fly pheremone

Answer 18

7,11-HD and 7,11-ND

Question 19

what can happen when males secrete cVa?

Answer 19

elicits aggression in other males

in some cases, young males respond to these pheromones and attempt to court elder males

Question 20

name a male pheromone

Answer 20

cVA and 7-t and 7-p

Question 21

name the receptor responsible for detecting these auditory vibrations

Answer 21

stretch receptors

Question 22

what receptor is involved in the female perception of male pheromones?

Answer 22

Or83b: Or67d receptor

Question 23

what OBP is involved in detection of male pheremones

Answer 23

Lush

Question 24

how does the female fly receive the courtship song

Answer 24

through her antennae - Johnstons organ in the Artista

Question 25

describe the evidence showing how Or67d was implicated in courtship behaviour

Answer 25

Jallon et al., 1981 = males lacking or67d display increased courtship toward males compared to wild-type controls.

Question 26

describe the process of how males receive non-volatile pheromones

Answer 26

non-volatile pheromones are detected by gustatory receptor neurons of the foreleg tarsi and mouthparts gustatory information is relayed from the SOG to a region of the lateral protocerebrum

Question 27

describe the process of how females receive volatile pheromones:

Answer 27

1. cVa enters the sensillar lymph via cuticle pores 2. cVa binds to Lush (OBP) to create a conformational change 3. activated lush binds to Or83b:0r67d receptor of olfactory sensory neurons 4. OSNs project to the Da1 or Va1m glomerulus of the antennal lobe 5. spatial info is conveyed to mushroom bodies via olfactory projection neurons

Question 28

describe how the LC10 visual input is integrated to initiate courtship

Answer 28

LC10 input is integrated into the higher order brain centre called the command centre - these project to the P1 cluster of neurons if the higher order brain centre decides to initiate courtship: - descending neurons project to the ventral ganglia to initiate song production.

Question 29

how does Johnstons organ trigger motor action

Answer 29

via the antennal mechanosensory and motor cortex

Question 30

where does Fruitless transcripts work

Answer 30

in the nervous system

Question 31

where does doublesex transcripts work

Answer 31

in neural and non-neuronal tissues

Question 32

what is sex lethal protein

Answer 32

an RNA binding protein that regulates the splicing of itself and downstream transformer genes mRNA

Question 33

what does action of sex lethal protein result in

Answer 33

translation of transformer

Question 34

what does transformer do?

Answer 34

regulates the splicing of two downstream genes in females : doublesex and fruitless

Question 35

how is sex lethal protein activated

Answer 35

the additional female X chromosome regulates splicing to produce sex lethal protein

Question 36

what happens in the absence of the female XX genotype

Answer 36

in males, the presence of only one X chromosome results in default splicing patterns - this means sex Lethal protein is not produced

Question 37

what happens in default splicing in males

Answer 37

yields functional Dsx male protein and Fru male protein

Question 38

how were the functions of fruitless and doubles assessed?

Answer 38

using mutants

Question 39

what happens in Dsx KO mutants

Answer 39

produce most aspects of courtship - except one part of the courtship song

Question 40

what happens if male Dsx is expressed in females

Answer 40

somatic differentiation - they transformed into males, but they could not perform courtship (Dsx not required for courtship behaviour)

Question 41

what happens to fru KO flies

Answer 41

phenotypically male but show no courtship behaviour

Question 42

what produces sex specific transcripts

Answer 42

P1 promoter

Question 43

what happens if these promoters are knocked out

Answer 43

it can be lethal

Question 44

how have fruitless proteins been studied in the CNS

Answer 44

using antibodies tagged with a fluorescent dye

Question 45

where has male fruitless been identified

Answer 45

brain, ventral ganglia, antennal lobe, SOG, lateral regions sensory neurons

Question 46

what were first used to identify sexually dimorphic CNS regions involved in male courtship

Answer 46

gynandromorphs

Question 47

how has the GAL4/UAS system been used to study sexually dimorphic brain circuitry?

Answer 47

using UAS-traF (female transformer) driven by GAL4 lines with distinct patterns in the CNS

Question 48

ER! What have gynandromorph studies revealed about the male courtship song?

Answer 48

only a single region in the dorsal protcerebrum must be genetically male for a fly to sing (this being a region rich in fruitless neurons if a small set of approx 20 fruitless neurons from a normal female are masculinised, then the female will sing

Question 49

what happens when the male GR32a receptor is mutated, and what does GR32a do and what happens to the wing

Answer 49

males with this mutation show increases courtship towards males and mated females the wings simultaneously extend during the courtship ritual

Question 50

name the OBP used in detecting female pheremones

Answer 50

OBP57d