Lecture 24 : Sensory Lecture 24 : Sensory trade offstrade offs

11/30/09

Opportunities at Shady Opportunities at Shady Grove Adventist HospitalGrove Adventist Hospital

Student scribes to work in emergency room

If interested, contactMichele LiscumScribes Americamichellel@scribeamerica.com

Final projects next weekFinal projects next week

NO assignment due this week

Next week presentationsMonday and Wednesday

Send me your powerpoint by noon on the day of your talk

Final projects due on Wednesday

MMoonnddaayy

# Who Topic

1 Aminah Ion transporter

2 Chloe Olfaction

3 Sohan Bat echolocation

4 Libby Electroreception

5 Uzair Sweet taste

6 Jamie Autism and senses

7 Karen FPR receptors

8 Shewa* Bat vision

9 Robin* Bitter taste

10 Samiha* Nocturnal color vision

WWeenneessddaayy

# Who Topic

1 Bobak Pheromones

2 Sonal Umami taste

3 Zan Bat vision

4 Nadia Sweet taste

5 John UV vision in birds

6 Laurene Barn owl hearing

7 Chris Spicy taste

8 Nidal Cat taste

9 Eric* Insect hearing

10 Jessica* Deep sea vision

11 Naomi* Umami taste

QuestionsQuestions

1. What are the trade off between senses?

2. When are senses lost? Is this related to gain in other senses?

VisionVision

Can have independent gain and loss of spectral sensitivitiesLose if no longer need Gain if new need arises

AnoleR

ChickR

AtigrinumR

GaustralisLWS

HumanG

HumanR

AnoleRH2

ChickG

TilapiaG1

ZebrafishG1

ZebrafishG2

GaustralisRhB

AnoleRH

ChickRh

HumanRh

XlaevisRH

ZebrafishRh

GaustralisRHA

AnoleS2

ChickB

ZebrafishB

GaustralisSWS2

AnoleS1

ChickUV

HumanB

GaustralisS1

ZebrafishUV

0.05 changes

LWS

RH2

SWS2

SWS1

RH1

Lamprey LWS

Lamprey RHB

Lamprey RHA

Lamprey S2

Lamprey S1

Trezise and Collin 2005

SWS2MonotremeSWS

1

RH2

SWS2

Davies et al 2007 Platypus

Marine mammalsMarine mammals

Evolved from land mammals

Land mammals have two cone opsins

SWS1M/LWS

Placental mammalsPlacental mammals

X

X X

X = loss SWS1

Marine mammalsMarine mammals

Unique gene losses in each lineage - separate events

New world vs Old worldNew world vs Old world

Multiple Multiple LWS LWS opsin opsin

genes in genes in OW and OW and

NW NW monkeysmonkeys

OW

NW

Human red and green Human red and green opsinsopsins

530 nm

560 nm

A

S

A

A164S=+2 nm

Y

F

T

F261Y=+10 nmA269T=+14 nm

LWS opsin sequences in LWS opsin sequences in primatesprimates

+2 +10 +14164 261 269

Human560 S Y THuman530 A F ACapuchin563 S Y TCapuchin550 A F TCapuchin535 A F AMarmoset563 S Y TMarmoset556 A Y TMarmoset543 A Y A

Combos of same sites in MWS and LWS of all OW monkeys

LWS opsin sequencesLWS opsin sequences

+2 +10 +14164 261 269

Human560 S Y THuman530 A F ACapuchin563 S Y TCapuchin550 A F TCapuchin535 A F AMarmoset563 S Y TMarmoset556 A Y TMarmoset543 A Y A

Alleles

Allele = different form of a gene which can vary in a group / population

OW

NW

Duplication event which caused tandem array of red and green genes to form

Duplicated about 30 MYa

OW

NW

Human

Gorilla

Chimpanzee

Marmoset

Capuchin

Howler

Tandem array in OW

NW monkeys - alleles

Most NW monkeysMost NW monkeys

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)

LWS SWS1

Allele Allele treetree

Old world gene duplication occurred 30 Mya

5-8% divergent

Howler monkey duplication is more recent

2.7% different

Why need trichromacyWhy 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.

Gelada, Ethiopia Theropithecus

gelada

Vervet monkey, East Africa

Cercopithecus aethiops 300 400 500 600 700

Wavelength, nm

0.0

0.5

1.0

Trichromacy enables new color signaling in primates.

Zhang and Webb 2003Zhang and Webb 2003

Vomeronasal receptor Vomeronasal receptor pathwaypathway

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 Trp2 is knocked out in OW primatesprimates

+ = open reading frame s = stop codon

Many V1R genes are also Many V1R genes are also pseudogenespseudogenes

Vomeronasal receptor Vomeronasal receptor pathwaypathway

V1R, V2R G protein

Phospholipase C

Trp2

Humans, great apes and OW monkeys do not have functioning VNO. Why?

Coincidence in timeCoincidence 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 statusIf can use vision to determine ovulatory status

then don’t need pheromones to communicate

Webb et al 2004Webb et al 2004

Relationship between Relationship between vision and VNO?vision and VNO?

Human Trichromat No VNO

OW primates Trichromat No VNO

NW primates Dichromat VNO

Howler Trichromat ??

Mammals Dichromat VNO

Birds Tetrachromat No VNO

If vision displaces VNOIf vision displaces VNO

Expect howler to also have lost VNO pathwayHowever, they find TRP2 gene is intact

in howlers Howlers also show behavioral

evidence that use VNOScent marking

Webb’s explanationWebb’s explanation

Gilad et al 2004: Does it Gilad et al 2004: Does it happen in olfaction?happen in olfaction?

MethodMethod

Used degenerate primers to amplify suite of OR genesExamine 18 primate speciesSequence 100 genesCalc % pseudo

Test method on human and mouse OR genes to see if identify diverse set

Test in human and mouseTest in human and mouse

Human

Mouse

Actual #

This method

% OR pseudogenes% OR pseudogenes

Results comparisonResults comparison

Before New

Apes 33% 36%

OWM 29.3% 32%

NWM 18.4% 18%

Howler 31% 31%

% OR pseudogenes% OR pseudogenes

Gains and lossesGains and losses

Do seem to be some trade offs

Will any of you find evidence for this in the species you are examining?