things I don't understand (1-4) Flashcards
what are the 4 principles of door discrimination
- approx 1000 odorant receptor genes dedicated to olfaction in mammals
- each OSN expresses a single OR (which has a distinct odor ligand profile)
- OSNs expressing the same receptor converge on the same glomerulus in the brain
- each door is encoded combinatorial = one odor can activate multiple ORs and each OR can respond to multiple odors
what percentage of ORNs co-expres
10-25%
what is the receptor for sugar
GR5A
what is the receptor for caffeine (bitter)
GR66A
where do male flies perceive non-volatile pheremones
on the foreleg tarsi
what cranial nerves innervate the taste buds
7, 9 and 10
what is found in the walls of papilla
sensory cells with microvilli arranged in pit-like invaginations
what is attracted to CO2
mosquitos
where are internal sensilla found
in the pharyngeal portion of the proboscis
what degrades period
how
double-time - by hyperphosphorylation and degradation by proteolysis
how does light reach clock neurons
via photoreceptive organs containing rhodopsin (e.g ocelli and HB-eyelets)
how many OBPs are currently known, where are they secreted from
52 currently known
secreted from support cells
what does a mutation to OR67d cause in male flies
inadequate pheromone detection
= they court mated females and male flies
describe the activity of DN1 neurons
in the evening, output of DN1 is weak in high light, but strongly increases in low light
what is the function of PDF neurons
synchronise clock neurons in the absence of light
what happens in flies with null alleles of clock and cycle
less overall sleep than wild-type flies
describe the process of arousal in neurons
light activates I-VLN
this releases PDF onto S-VLNs that project onto ellipsoid bodies to increase motor activity
how do neurons control sleep
GABAergic sleep promoting neurons inhibit the arousal of I-VLN and S-VLNs
what does VLN stand for
ventral lateral neurons
temperature cycles are able to entrain the clock under constant light or dark cycles, what does this mean
there is an override of the light dependent degradation of timeless
describe the evidence suggesting temperature reception is a tissue-autonomous process
isolated body parts are able to perceive temperature unlike isolated brains
what gene is implicated in temperature reception
norpA gene
what happens to animals carrying mutated norpA
they are unable to synchronise to temperature cycles
what other gene is said to be implicated in temperature reception
Nocte gene
describe the Siffre study
in 1962, Siffre spent 6 months with no exposure to light
his circadian rhythm remained consistent at 24 hours and 30 minutes
supporting evidence for the fact that circadian rhythms free run under constant conditions
what higher order brain centre perceives sex peptide
SOG
what centre of the female brain responds to auditory information
antennal mechanosensory and motor cortex
in which sex is sex lethal protein only produced
in females
what does the absence of sex lethal protein in males mean
transformer mRNA is spliced in the default pattern
what happens in Fruitless null male flies
phenotypically male but they cannot court
where are the sex specific transcripts of Dsx and Fruitless produced
P1 promoter (KO of these promoters is lethal)
what does command centre visual info project to? what happens next
P1 cluster of neurons
- they activate descending neurons that project down to the ventral ganglia
what is the evidence for sex peptide in making females unreceptive
virgin females injected with sex peptide become unreceptive to mating
what have gynandromorph studies revealed about the male courtship
only a single region in the dorsal protocerebrum needs to be genetically male for the fly to sing
(this region is rich in fruitless neurons)
what OBP is used to detect female pheremones
OBP57d
what receptor is involved in perceiving female pheromones (gustatorily)
GR32A
what do mutations to GR32A mean
males show increased courtship towards males and mated females
the wings simultaneously extend during the courtship ritual.
