Pheromones

Question 1

What is a pheromone?

Answer 1

A chemical released by one individual that triggers a specific behavioural or developmental response in another of the same species.

Question 2

What is an example of an extremely potent pheromone?

Answer 2

Bombykol (silk moth sex attractant), detectable over ~2 km.

Question 3

What is the rabbit mammary pheromone and its effect?

Answer 3

2-methylbut-2-enal; triggers nipple-search behaviour in pups.

Question 4

Which pheromones attract female pigs?

Answer 4

Androstenone and androstenol from boar saliva (foaming aids dispersion).

Question 5

What is the mouse alarm pheromone, and where is it detected?

Answer 5

2-sec-butyl-4,5-dihydrothiazole; detected by the Grueneberg ganglion.

Question 6

What is the function of the Grueneberg ganglion?

Answer 6

Specialized danger cue detector; removal abolishes alarm freezing behaviour.

Question 7

What are the major mammalian chemosensory subsystems?

Answer 7

MOE, VNO, Grueneberg ganglion, septal organ, guanylyl cyclase-dependent OSNs.

Question 8

What ligands do V1Rs, V2Rs, and FPRs detect in the VNO?

Answer 8

V1Rs: small volatiles; V2Rs: peptides/MHC; FPRs: pathogen-related cues.

Question 9

How do stimuli access the VNO?

Answer 9

Via Flehmen in many mammals or vascular pumping in rodents.

Question 10

What behavioural changes occur in TRPC2 knockout mice?

Answer 10

Loss of aggression and sex discrimination; males mount both sexes.

Question 11

What are major urinary proteins (MUPs)?

Answer 11

Long-lasting, non-volatile urine proteins that bind volatiles and encode individual identity.

Question 12

What is countermarking?

Answer 12

A male urinates over another male’s scent mark to assert territory and identity.

Question 13

What is ESP1, and what does it do?

Answer 13

A male tear peptide pheromone detected by V2Rp5; enhances lordosis in females.

Question 14

What is the canonical VNO transduction pathway?

Answer 14

Ligand → V1R/V2R → G-protein → PLC → IP₃ + DAG → TRPC2 opens → Na⁺/Ca²⁺ influx.

Question 15

What distinguishes V1R vs V2R VSNs?

Answer 15

V1R neurons detect specific small volatiles; V2R neurons detect MHC peptides giving genotype/kinship info.

Question 16

Do humans have sex pheromones?

Answer 16

No clear evidence; humans rely more on learned signature mixtures than true pheromones.