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Diurnal and circadian rhythms

Diurnal and circadian rhythms. Eva Farre. Objectives for today: Students will be able to: Distinguish between circadian vs. diurnal rhythms

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Diurnal and circadian rhythms

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  1. Diurnal and circadian rhythms Eva Farre

  2. Objectives for today: • Students will be able to: • Distinguish between circadian vs. diurnal rhythms • Create a diurnal model that illustrates normal time of physiological and metabolic processes in plants, then predict the changes the model in response to specific environmental perturbations. • Apply the concept of entrainment by designing an experiment and interpreting the results. • Explain the concepts of “gating” that is illustrated in several different models. • Interpet the role of the circadian clock in photoperiodism • Predict the evolutionary advantage of circadian rhythms

  3. Daylight saving time Q1. What is the difference between circadian and diurnal rhythms in animals? Talk to you neighbor. Prepare to report out.

  4. Endogenous rhythms: for example circadian Q2. What are other examples of endogenous rhythms in living organisms? Brainstorm in your group. Report out. http://www.dartmouth.edu/~rmcclung/NiceMovie.html

  5. Circadian vs. diurnal rhythms

  6. Daylight saving time: Entrainment How do we design experiments to test endogenous rhythms of metabolic processes in plants?

  7. Entrainment experiment Q3. Predict the growth pattern of the seedling in frame 3. What is the rationale for your prediction? Individuals write on carbonless paper.

  8. CAB2:LUC Thain et al., Curr Biol 2000 Entrainability of circadian clocks http://millar.bio.ed.ac.uk/video.html

  9. Basic structure of an eukaryotic circadian clock

  10. Q4: In pairs, place these physiological and metabolic processes at the appropriate time of day when the activity occurs. Draw and label the model on your carbonless. Heat adaptation genes Anthocyanin production Drought acclimation genes Respiration Photosynthesis Respiration Growth Carbon assimilation Carbon assimilation Starch synthesis Stomatal opening Starch degradation Stomatal opening Cold acclimation genes Convington et al. 2008 Michael et al., 2008 Nozue et al., 2007

  11. Q5. What happens to circadian processes under constant conditions?

  12. Q6. Interpret the patterns of CO2 assimilation represented in this figure. Base on this evidence, what conclusion can you draw about this metabolic process on constant conditions? Mutant Wild-type Time in continuous light Dodd et al., 2005

  13. Q7. Examine the next three figures: Circadian clocks: light Circadian clocks: cold Circadian clocks: flowering Based on the evidence provided in each figure, what does “gates” mean in each case. Remember, gates is a process in each of these models. Write in your carbonless.

  14. The circadian clock “gates” signaling pathways: light CAB2:LUC McWatters et al., 2000

  15. The circadian clock “gates” signaling pathways: cold Fowler et al., 2005

  16. The circadian clock “gates” signaling pathways: flowering Imaizumi and Kay, 2006

  17. The right circadian clock represents a competitive advantage Mutant P28= 30 hr Wild type = 25 hr Q8. Explain the results of this experiment in terms of the evolutionary advantage to one of the populations (which one? And why?) Ouyang et al, 1998

  18. Period 28 h 20 h The circadian clock is essential for optimal growth of plants T24 T20 T28 Dodd et al. Science (2005)

  19. Concepts: • Circadian vs. diurnal rhythms • Entrainment • Gating • Role of the circadian clock in photoperiodism • Evolutionary advantage of circadian rhythms

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