Sensory Encoding of Smell in the Olfactory System of Drosophila
Taste & Smell. Smell vs. Taste? Nose Sensors in the Olfactory Epithelium Many uses, including food...
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Transcript of Taste & Smell. Smell vs. Taste? Nose Sensors in the Olfactory Epithelium Many uses, including food...
Taste & Smell
Smell vs. Taste?
• Nose
• Sensors in the Olfactory Epithelium
• Many uses, including food location
• Nose
• Sensors in the Olfactory Epithelium
• Many uses, including food location
• Mouth, & many places
• Taste buds SCC
• Primarily for feeding
• Mouth, & many places
• Taste buds SCC
• Primarily for feeding
WaterFlow
OlfactoryEpithelium
Flaps
Flaps direct water through the nares and over the
olfactory epithelium
Water Flow
ReliesHeavilyOn Smell
Smell not important
Olfactory Epithelium Ciliated Cells
Molecules Whooshing by in the Water
Nerves to the brain
Every Odor Molecule is a Little Bit Different
Molecule “ keys” fit in olfactory cell “locks” and the fish perceives the smell of red squares, yellow circles, and purple triangles. This fish
can’t smell or .
Nerves to the brain
0 50 500
• Amino acids: The building blocks of protein. Some amino acids are more stimulatory than others.
• Steroids: Some fish are highly sensitive to hormones especially those related to reproductive activities– Prostaglandins: Hormones released
by female fish upon ovulation.
Amino acids at concentrations of 1
part in 200,000,000,000
steroid hormones at 1 in
30,000,000,000,000
1 in 200 billion = 6 mg/acre-ft
1 in 30 Trillion =0.04mg/ acre ft
800,000,000,000,000 molecules/tsp800,000,000,000,000 molecules/tsp
5,600,000,000 molecules/tsp5,600,000,000 molecules/tsp
Taste Bud
NerveDermis
Epidermis
Water
What Can They Taste ?
What Can They Taste ?
• sweet, sour, bitter, salty, uma • Amino acids• Steroids: Sex hormones• Organic acids and nucleotides: • Carbon Dioxide: ??• Peptide toxins: Like marine puffer
toxin
Solitary Chemoreceptor Cells:
SCC• Dispersed on external surface of fish
as well as on gills and in the oral cavity.
• These cells are sensitive to amino acids in some species but not others.
• They are especially adept at detecting fish mucus and some organic acids.
Rockling
•6 million SCC
•dorsal fin•Prey detection
Dorsal fin-Mucus and bile-Predator avoidance
100 per square millimeter on
minnows and carp!
Smell in Action
Smell in Action
SalmonMigration
2,300 miles
Yukon River
Yukon River
Snake River
Headwaters
Pacifi
c
Life Cycles
• Eggs: found in a redd
• Alevin: fry with yolk
• Parr: Fingerlings in fresh water, black bars
• Smolt: Fingerling ready for the sea, silver
• Adult: In the sea
Spawns and then dies
Parr
Does not die, returns to the sea
Alevin
Alevin
Parr
Parr
Parr
Parr
Smolt
Imprinting Theory
• Each stream has a unique chemical signature
• Young salmon learn the smell of their river
• Later as adults they home in on that smell and return home
• Each stream has a unique chemical signature
• Young salmon learn the smell of their river
• Later as adults they home in on that smell and return home
Imprinting
Pheromone Theory
• Young salmon live in the river for 2-5 years before migrating
• Young salmon are genetically similar to the adult salmon in the sea
• Young salmon release pheromones specific to their population
• Mature salmon smell the young and find the stream
• Young salmon live in the river for 2-5 years before migrating
• Young salmon are genetically similar to the adult salmon in the sea
• Young salmon release pheromones specific to their population
• Mature salmon smell the young and find the stream
Pheromone
Homing Theories
•Imprinting: Salmon smell the stream
•Pheromone: Salmon smell their kin
•Which is right?
Stream Odorant Stream Odorant ExperimentsExperiments
Pheromone: Pheromone: Kin recognitionKin recognition
Adult Ranges of Pacific Salmon
S
N
QUIZ•Difference between taste
and smell•Lock and Key •Functions of taste and smell•Salmon life cycle (egg,
alevin, parr, smolt adult)•Salmon migration
Smell•Nares and SSC•Lock and key
Taste•Barbles, lips, mouth, skin
•Mostly for food•Also lock and key
Taste and
Smell
• Safety– Fright Reaction– Toxin detection
• Feeding– Finding Food– Testing food
• Reproduction– Kin recognition– Homing– Reproductive Hormones
• Eggs: found in a redd
• Alevin: fry with yolk
• Parr: Fingerlings in fresh water, black bars
• Smolt: Fingerling ready for the sea, silver
• Adult: In the sea