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Lecture 24 : Sensory trade offs

Lecture 24 : Sensory trade offs. 11/30/09. Opportunities at Shady Grove Adventist Hospital. Student scribes to work in emergency room If interested, contact Michele Liscum Scribes America michellel@scribeamerica.com. Final projects next week. NO assignment due this week

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Lecture 24 : Sensory trade offs

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  1. Lecture 24 : Sensory trade offs 11/30/09

  2. Opportunities at Shady Grove Adventist Hospital • Student scribes to work in emergency room • If interested, contact • Michele Liscum • Scribes America • michellel@scribeamerica.com

  3. 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

  4. Monday

  5. Wenesday

  6. Questions • What are the trade off between senses? • When are senses lost? Is this related to gain in other senses?

  7. Vision • Can have independent gain and loss of spectral sensitivities • Lose if no longer need • Gain if new need arises

  8. LWS Lamprey LWS RH2 Lamprey RHB RH1 Lamprey RHA SWS2 Lamprey S2 SWS1 Lamprey S1

  9. Trezise and Collin 2005

  10. RH2 SWS1 Monotreme SWS2 Davies et al 2007 Platypus SWS2

  11. Marine mammals • Evolved from land mammals • Land mammals have two cone opsins • SWS1 • M/LWS

  12. Placental mammals X = loss SWS1 X X X

  13. Marine mammals Unique gene losses in each lineage - separate events

  14. New world vs Old world

  15. Multiple LWS opsin genes in OW and NW monkeys OW NW

  16. A F A 530 nm 560 nm S Y T F261Y=+10 nm A269T=+14 nm A164S=+2 nm Human red and green opsins

  17. LWS opsin sequences in primates +2 +10 +14 164 261 269 Human560 S Y T Human530 A F A Capuchin563 S Y T Capuchin550 A F T Capuchin535 A F A Marmoset563 S Y T Marmoset556 AY T Marmoset543 AYA Combos of same sites in MWS and LWS of all OW monkeys

  18. LWS opsin sequences +2 +10 +14 164 261 269 Human560 S Y T Human530 A F A Capuchin563 S Y T Capuchin550 A F T Capuchin535 A F A Marmoset563 S Y T Marmoset556 AY T Marmoset543 AYA Alleles Allele = different form of a gene which can vary in a group / population

  19. Duplication event which caused tandem array of red and green genes to form OW NW Duplicated about 30 MYa

  20. Tandem array in OW Human Gorilla Chimpanzee Marmoset Capuchin Howler OW NW monkeys - alleles NW

  21. Most NW monkeys LWS SWS1 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)

  22. Allele tree Old world gene duplication occurred 30 Mya 5-8% divergent Howler monkey duplication is more recent 2.7% different

  23. Why need trichromacy • Following slides from talk by Jim Bowmaker, University College London

  24. Why trichromacy? Why two ‘LWS’ cone types? Dichromacy with a single LWS and an SWS1 cone type gives no red-green discrimination.

  25. 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.

  26. Gelada, Ethiopia Theropithecus gelada Vervet monkey, East Africa Cercopithecus aethiops Trichromacy enables new color signaling in primates.

  27. Zhang and Webb 2003

  28. Vomeronasal receptor pathway G protein V1R, V2R Phospholipase C Trp2 Humans, great apes and OW monkeys do not have functioning VNO. Why?

  29. Trp2 is knocked out in OW primates + = open reading frame s = stop codon

  30. Many V1R genes are also pseudogenes

  31. Vomeronasal receptor pathway G protein V1R, V2R Phospholipase C Trp2 Humans, great apes and OW monkeys do not have functioning VNO. Why?

  32. 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

  33. Webb et al 2004

  34. Relationship between 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

  35. 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

  36. Webb’s explanation

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

  38. 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

  39. Test in human and mouse Human Mouse Actual # This method

  40. % OR pseudogenes

  41. Results comparison

  42. % OR pseudogenes

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