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Lecture #11. Invertebrate visual pigments 3 /5/13. Homework comments. If you send it in word, I have put comments on it You may have to track changes to see those comments Is that working??. Mathematical relationships. Sensitivity ≈D 2 If D doubles sensitivity increases x4

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Lecture #11


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    1. Lecture #11 Invertebrate visual pigments 3/5/13

    2. Homework comments • If you send it in word, I have put comments on it • You may have to track changes to see those comments • Is that working??

    3. Mathematical relationships • Sensitivity ≈D2 • If D doubles sensitivity increases x4 • This is a quadratic increase - not an exponential increase • Sensitivity ≈ exp (D) This would increase exponentially

    4. Quadratic and exponential are both steeper than linear

    5. Check out equation sheet for exam

    6. Today • Visual pigments in invertebrates • Behavioral determination • Diurnal and nocturnal color vision

    7. Invertebrate visual pigments

    8. Karl von Frisch • Nobel prize in physiology, 1973 • Studied the sensory system of bees • Determined visual sensitivities from behavioral experiments

    9. Eyes of a bee

    10. Von Frisch bee training experiment Trained bees to come to a blue card by rewarding them with sugar water. Sugar water

    11. Do bees come back to blue card?

    12. Doesn’t mean they can detect colors Might only be sensing brightness

    13. Bee color discrimination • “Asked” bees if they could tell blue apart from many shades of gray • If they can discriminate blue, they will visit only the blue card and not any gray ones Color vision Monochromatic vision

    14. Color discrimination

    15. Try to train bee to different colors

    16. If test the bees to different colors Can see blue but confuse it with purple Can distinguish blue from blue-green Can see yellow but can’t tell apart from orange Can tell blue apart from blue with UV light shining on it UV

    17. Questions? • What experimental controls are needed? • What visual pigments does a bee have?

    18. What is the bee’s visual system?? /Yellow Briscoe and Chittka 2001

    19. Human visual pigments λmax = 420, 535, 565 nm Normal

    20. Spectral flowers More sophisticated testing by creating flowers with narrow band light Daumer 1956 Lotto et al 2005

    21. Set up test grid to see if can train bees to go to middle flowers

    22. The data Bees can correctly learn to feed at the middle flowers Note: Some bees prefer one color

    23. Were they trained to position or just color?

    24. Once add 3rd color – bees choose by chance

    25. Can they be trained to go to the corners?

    26. Results

    27. Conclusions

    28. Ted talk

    29. Bee training

    30. Color discrimination is best if pigments overlap some but not too much Human visual pigments Cone pigments Rod pigment

    31. Color wheel • This color wheel is based on three primary colors: • R Y B • These are primaries for pigment colors. • The secondary colors are mixtures of primaries • O=R+Y • G=Y+B • V=R+B

    32. Primary Green/ Yellow Blue- green Bee purple UV Blue Secondary Bee violet Bee color system • Put bee color vision on color wheel

    33. Flower light reflectance UV • Flowers appear yellow to us • Often have central portion which has UV reflectance UV Nectar guide

    34. Flowers in visible and UV light

    35. Most diverse invertebrates are insects • Live in many different habitats • Under ground • Cave • Aquatic • Forest • Field • Live in different light conditions • Diurnal to nocturnal

    36. Insect visual pigments • Opsin protein bound to the chromophore • Insects have two chromophores • A1 11-cis retinal vitamin A1 carotene • A3 11-cis 3-hydroxyretinal xanthophylls • In combination with same opsin, each chromophore makes a visual pigment which absorb at slightly different wavelengths

    37. Compound eye = many ommatidia Visual pigments are in rhabdoms

    38. Photoreceptors Ciliary Microvillar Rod Cone Octopus Insect

    39. Rhabdoms • Each visual cell has a microvillar part • The microvilli of all the visual cells project into the center to make the rhabdom

    40. Rhabdoms • The microvilli contain the visual pigment • Absorption of light excites the visual cells

    41. Bee ommatidium UV B G

    42. Spaethe and Briscoe 2005

    43. Bees have compound eyes and ocelli Ocelli are used for navigation and also contain UV opsins

    44. Drosophila eyes WT cinnabar sepia white 800 ommatidia per eye

    45. Drosophila ommatidium • There are 8 rhabdomeres that make up rhabdom • 6 are around center • 2 in center - one on top of the other • Cells are numbered • R1-6 • R7, R8

    46. Drosophila visual pigments Pigments are numbered Rh1-Rh6

    47. Visual pigment arrangements Light The six outer rhabdomeres (R1-R6) surround the two inner ones. Inner ones are one on top of other, R7 and R8 The same visual pigment is in R1-R6 Rh1 - green R1-R6 used for motion detection

    48. Drosophila visual pigment Rh1 is in most of rhabdomeres (R1-6)

    49. Two combinations for R7/R8 cells