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A generalized receptor law governs
phototaxis in the phytoplankton
Euglena gracilis
Giometto, Altermatt, Maritan, Stocker,...
Phytoplankton
• Primary producers in aquatic habitats
• Major sink for atmospheric carbon dioxide
• Inhabit the photic zon...
Active movement
Cilia / flagella
Buoyancy control
Response to environmental cues
Chemotaxis
Gravitaxis
Phototaxis
Phytopla...
Phototactic algae: typical features
• Photopigments
• Stigma
• Spiral swimming
Euglena and Chlamydomonas sketches from:
Jé...
Volvox carteri
Drescher, K., Goldstein, R. E., & Tuval, I. (2010). PNAS, 107, 11171–11176
Population-level dynamics
• Keller-Segel model for chemotaxis
• Advection velocity
• Chemotactic potential f[s] determines...
Tindall, M. J., Maini, P. K., Porter, S. L., & Armitage, J. P. (2008). Bulletin of Mathematical Biology 70, 1570–1607
Tindall, M. J., Maini, P. K., Porter, S. L., & Armitage, J. P. (2008). Bulletin of Mathematical Biology 70, 1570–1607
© Micronaut, Martin Oeggerli
Phototactic potential?
Euglena gracilis
Eyespot absorption spectrum
B R
Strother, G., and Wol...
Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050
Red LED Red LED
Red light
Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-705...
Blue light
Blue LED
Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050
Alga...
Blue light
Blue LED
Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050
Alga...
Blue light
Blue LED
Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050
Alga...
Blue light
Blue LED
Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050
Alga...
Blue light
Blue LED
Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050
Alga...
Blue light
Blue LED
Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050
Alga...
Blue light
Blue LED
Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050
Alga...
Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050
r(x) =
r(x)
r(-L)
= exp
f[I(x)]
D
é
ëê
ù
ûú
Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015)...
Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050
Phototactic potential
Me...
Generalized Receptor Law
f(I) = aI
Ic - I
Ir + I
Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (...
Phototactic potential
Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050
r(...
Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050
Temporal dynamics
• Modeling vertical distribution of phytoplankton
• Harvesting in photobioreactors
• Transport of colloidal particles
Giom...
Coauthors
Amos Maritan, Roman Stocker, Florian Altermatt, Andrea Rinaldo
Funding
Eawag Discretionary Funds
Swiss National ...
Euglena picture: http://www.dr-ralf-wagner.de/
Absorption spectra:
Strother, G., and Wolken, J. (1961) J. Protozool. 8
Eye...
A generalized receptor law governs phototaxis in the phytoplankton Euglena gracilis - Giometto, Altermatt, Maritan, Stock...
A generalized receptor law governs phototaxis in the phytoplankton Euglena gracilis - Giometto, Altermatt, Maritan, Stock...
A generalized receptor law governs phototaxis in the phytoplankton Euglena gracilis - Giometto, Altermatt, Maritan, Stock...
A generalized receptor law governs phototaxis in the phytoplankton Euglena gracilis - Giometto, Altermatt, Maritan, Stock...
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A generalized receptor law governs phototaxis in the phytoplankton Euglena gracilis - Giometto, Altermatt, Maritan, Stocker, Rinaldo

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A generalized receptor law governs phototaxis in the phytoplankton Euglena gracilis - Giometto, Altermatt, Maritan, Stocker, Rinaldo

  1. 1. A generalized receptor law governs phototaxis in the phytoplankton Euglena gracilis Giometto, Altermatt, Maritan, Stocker, Rinaldo © Micronaut, Martin Oeggerli
  2. 2. Phytoplankton • Primary producers in aquatic habitats • Major sink for atmospheric carbon dioxide • Inhabit the photic zone of the water column © ESA, 2012
  3. 3. Active movement Cilia / flagella Buoyancy control Response to environmental cues Chemotaxis Gravitaxis Phototaxis Phytoplankton movement Donat P. Häder
  4. 4. Phototactic algae: typical features • Photopigments • Stigma • Spiral swimming Euglena and Chlamydomonas sketches from: Jékely, G. (2009). Phil Trans R Soc B 364, 2795-2808 Video from: J. Vidyadharan and K. Foster, http://fosterlab.syr.edu
  5. 5. Volvox carteri Drescher, K., Goldstein, R. E., & Tuval, I. (2010). PNAS, 107, 11171–11176
  6. 6. Population-level dynamics • Keller-Segel model for chemotaxis • Advection velocity • Chemotactic potential f[s] determines response to attractant concentration s • Keller-Segel (1971) f[s]=log[s] • Lapidus-Schiller (1976) Receptor law f[s]=s/(s+k), k constant v(x) = c[s(x)] ds(x) dx º df[s(x)] dx Rhodobacter sphaeroides in oxygen gradient Bacterial band E. Coli chemotactic rings ¶r(x,t) ¶t = D ¶2 r(x,t) ¶x2 - ¶ ¶x c[s(x)] ds(x) dx r(x,t) é ëê ù ûú Tindall, M. J., Maini, P. K., Porter, S. L., & Armitage, J. P. (2008). Bulletin of Mathematical Biology 70, 1570–1607 v(x)
  7. 7. Tindall, M. J., Maini, P. K., Porter, S. L., & Armitage, J. P. (2008). Bulletin of Mathematical Biology 70, 1570–1607
  8. 8. Tindall, M. J., Maini, P. K., Porter, S. L., & Armitage, J. P. (2008). Bulletin of Mathematical Biology 70, 1570–1607
  9. 9. © Micronaut, Martin Oeggerli Phototactic potential? Euglena gracilis Eyespot absorption spectrum B R Strother, G., and Wolken, J. (1961) J. Protozool. 8
  10. 10. Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050
  11. 11. Red LED Red LED Red light Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050 Algaldensity (re-normalized)
  12. 12. Blue light Blue LED Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050 Algaldensity (re-normalized)
  13. 13. Blue light Blue LED Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050 Algaldensity (re-normalized)
  14. 14. Blue light Blue LED Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050 Algaldensity (re-normalized)
  15. 15. Blue light Blue LED Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050 Algaldensity (re-normalized)
  16. 16. Blue light Blue LED Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050 Algaldensity (re-normalized)
  17. 17. Blue light Blue LED Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050 Algaldensity (re-normalized)
  18. 18. Blue light Blue LED Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050 Algaldensity (re-normalized)
  19. 19. Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050
  20. 20. r(x) = r(x) r(-L) = exp f[I(x)] D é ëê ù ûú Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050 Stationary algal distribution Keller-Segel-like phototaxis model ¶r(x,t) ¶t = D ¶2 r(x,t) ¶x2 - ¶ ¶x df[I(x)] dx r(x,t) é ëê ù ûú Population-level dynamics f(I) = Dlog r[x(I)][ ] Phototactic potential v(x) Measured Measured
  21. 21. Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050 Phototactic potential Measured in the experimentsTypical irradiance at sea level f(I) = Dlog r[x(I)][ ] Lightintensity r(x) = r(x) r(-L) = exp f[I(x)] D é ëê ù ûú Infer f from dataStationary algal distributions
  22. 22. Generalized Receptor Law f(I) = aI Ic - I Ir + I Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050 Phototactic potential r(x) = r(x) r(-L) = exp f[I(x)] D é ëê ù ûú v(x) = c[s(x)] ds(x) dx º df[s(x)] dx f(I) = Dlog r[x(I)][ ]
  23. 23. Phototactic potential Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050 r(x) = r(x) r(-L) = exp f[I(x)] D é ëê ù ûú Generalized Receptor Law f(I) = aI Ic - I Ir + I
  24. 24. Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050 Temporal dynamics
  25. 25. • Modeling vertical distribution of phytoplankton • Harvesting in photobioreactors • Transport of colloidal particles Giometto, A., Altermatt, F., Maritan, A., Stocker, R., and Rinaldo, A., (2015) PNAS 112:7045-7050 Possible applications
  26. 26. Coauthors Amos Maritan, Roman Stocker, Florian Altermatt, Andrea Rinaldo Funding Eawag Discretionary Funds Swiss National Science Foundation Thank you!
  27. 27. Euglena picture: http://www.dr-ralf-wagner.de/ Absorption spectra: Strother, G., and Wolken, J. (1961) J. Protozool. 8 Eyespot absorption spectrum Chloroplast absorption spectrum B B R R Study species: Euglena gracilis 30

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