Transcript Genomics of sensory systems - University of Maryland

Lecture 24 : Sensory trade
offs
11/30/09
Opportunities at Shady Grove
Adventist Hospital
 Student
scribes to work in emergency
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 If interested, contact
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Scribes America
[email protected]
Final projects next week
 NO
assignment due this week
 Next
week presentations
Monday and Wednesday
 Send
me your powerpoint by noon on
the day of your talk
 Final projects due on Wednesday
M
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Who
Aminah
Chloe
Sohan
Libby
Uzair
Jamie
Karen
Shewa*
Robin*
Samiha*
Topic
Ion transporter
Olfaction
Bat echolocation
Electroreception
Sweet taste
Autism and senses
FPR receptors
Bat vision
Bitter taste
Nocturnal color vision
W
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Who
Bobak
Sonal
Zan
Nadia
John
Laurene
Chris
Nidal
Eric*
Jessica*
Naomi*
Topic
Pheromones
Umami taste
Bat vision
Sweet taste
UV vision in birds
Barn owl hearing
Spicy taste
Cat taste
Insect hearing
Deep sea vision
Umami taste
Questions
1. What are the trade off between
senses?
2. When are senses lost? Is this related
to gain in other senses?
Vision
 Can
have independent gain and
loss of spectral sensitivities
Lose if no longer need
Gain if new need arises
AnoleR
ChickR
AtigrinumR
LWS
GaustralisLWS
Lamprey
LWS
HumanG
HumanR
AnoleRH2
ChickG
TilapiaG1
RH2
ZebrafishG1
ZebrafishG2
GaustralisRhB
Lamprey RHB
AnoleRH
ChickRh
HumanRh
RH1
XlaevisRH
ZebrafishRh
GaustralisRHA
Lamprey RHA
AnoleS2
SWS2
ChickB
ZebrafishB
GaustralisSWS2
Lamprey S2
AnoleS1
ChickUV
SWS1
HumanB
GaustralisS1
Lamprey S1
ZebrafishUV
Trezise and Collin 2005
RH2
SWS
1
Davies et al 2007 Platypus
SWS2
SWS2
Monotreme
Marine mammals
Evolved from land
mammals
 Land mammals
have two cone
opsins

SWS1
M/LWS
Placental mammals
X = loss SWS1
X
X X
Marine mammals
Unique gene losses in each lineage - separate events
New world vs Old world
OW
NW
Multiple
LWS opsin
genes in
OW and
NW
monkeys
Human red and green opsins
A
FA
530 nm
560 nm
S
A164S=+2 nm
YT
F261Y=+10 nm
A269T=+14 nm
LWS opsin sequences in
primates
Human560
Human530
Capuchin563
Capuchin550
Capuchin535
Marmoset563
Marmoset556
Marmoset543
+2
164
S
A
S
A
A
S
A
A
+10
261
Y
F
Y
F
F
Y
Y
Y
+14
269
T
A
T
T
A
T
T
A
Combos of same
sites in MWS and
LWS of all OW
monkeys
LWS opsin sequences
Human560
Human530
Capuchin563
Capuchin550
Capuchin535
Marmoset563
Marmoset556
Marmoset543
+2
164
S
A
S
A
A
S
A
A
+10
261
Y
F
Y
F
F
Y
Y
Y
+14
269
T
A
T
T
A
T
T
A
Alleles
Allele = different form
of a gene which can
vary in a group /
population
Duplication event
which caused tandem
array of red and green
genes to form
OW
NW
Duplicated about 30 MYa
Tandem array in OW
Human
OW
Gorilla
Chimpanzee
NW monkeys - alleles
Marmoset
NW
Capuchin
Howler
Most NW monkeys
LWS
Males XY
3 possible
dichromats
Females XX
3 possible
dichromats
(R/R, O/O or
G/G) and
3 possible
trichromats
(R/O, R/G or
O/G)
SWS1
Allele tree
Old world gene
duplication occurred 30
Mya
5-8% divergent
Howler monkey
duplication is more
recent
2.7% different
Why need trichromacy
 Following
slides from talk by Jim
Bowmaker, University College London
Why trichromacy? Why two ‘LWS’ cone types?
Dichromacy with a single LWS and an SWS1
cone type gives no red-green discrimination.
Trichromacy with two ‘LWS’ cone types and an SWS1 cone
gives red-green discrimination.
Ripe fruit and young, more reddish leaves can be detected
against the dappled green foliage.
Trichromacy enables new color signaling in primates.
Relative absorbance
1.0
Vervet monkey,
East Africa
Cercopithecus
aethiops
Gelada, Ethiopia
Theropithecus
gelada
0.5
0.0
300
400
500
600
Wavelength, nm
700
Zhang and Webb 2003
Vomeronasal receptor
pathway
V1R, V2R
G protein
Phospholipase C
Trp2
Humans, great apes and OW monkeys do not have
functioning VNO. Why?
Trp2 is knocked out in OW
primates
+ = open reading frame
s = stop
Many V1R genes are also
pseudogenes
Vomeronasal receptor
pathway
V1R, V2R
G protein
Phospholipase C
Trp2
Humans, great apes and OW monkeys do not have
functioning VNO. Why?
Coincidence in time
Trp2 gene lost 23-35 Mya
 Lost V1R gene about 24 MY


Opsin gene duplication was <35 MY

Primates use sexual skin swelling to indicate
ovulatory status
If can use vision to determine ovulatory status then
don’t need pheromones to communicate
Webb et al 2004
Relationship between vision
and VNO?
Human
Trichromat No VNO
OW primates
Trichromat No VNO
NW primates
Dichromat
VNO
Howler
Trichromat
??
Mammals
Dichromat
Birds
Tetrachromat No VNO
VNO
If vision displaces VNO
 Expect
howler to also have lost VNO
pathway
However, they find TRP2 gene is intact in
howlers
 Howlers
also show behavioral evidence
that use VNO
Scent marking
Webb’s explanation
Gilad et al 2004: Does it
happen in olfaction?
Method
 Used
degenerate primers to amplify
suite of OR genes
Examine 18 primate species
Sequence 100 genes
Calc % pseudo
 Test
method on human and mouse OR
genes to see if identify diverse set
Test in human and mouse
Human
Actual #
Mouse
This
method
% OR pseudogenes
Results comparison
Before
New
Apes
33%
36%
OWM
29.3%
32%
NWM
18.4%
18%
Howler
31%
31%
% OR pseudogenes
Gains and losses
 Do
seem to be some trade offs
 Will
any of you find evidence for this in
the species you are examining?