1. MCB 186 CIRCADIAN BIOLOGY Week 1 Biological rhythms & Circadian Clocks Free running period & environmental effects September 19, 2007 J. W. Hastings

2. THERE ARE MANY DIFFERENT BIOLOGICAL RHYTHMS WITH PERIODS RANGING FROM MILLISECONDS TO YEARS

3. BIOLOGICAL CYCLES SHORTER (ULTRA) & LONGER(INFRA) THAN CIRCADIAN

4. YEAST ULTRADIAN OSCILLATION of DISSOLVED OXYGEN 2001 Murray et al. J. Bacteriol. ~44 min/cycle

5. GOLDEN MANTLED SQUIRRELS - CIRCANNUAL RHYTHMS OF HIBERNATION

6. ANNUAL RHYTHM: DINOFLAGELLATE CYST GERMINATION Alexandrium fundyense PATRICIA MATRAI,

7. MENSTRUAL PERIODS (FOUR BIRTHS; WINFREE, 1980)

8. MOST ORGANISMS also EXHIBIT CIRCADIAN RHYTHMS in MANY DIFFERENT PROCESSES SUCH RHYTHMS CONTINUE in CONSTANT CONDITIONS = FREE RUNNING RHYTHM PERIOD NOT EXACTLY 24 HOURS CIRCA = ABOUT DIAN = ONE DAY

9. FREE RUNNING RHYTHMS HUMAN IN CONSTANT CONDITIONS FOR 24 DAYS

10. How can we more easily measure or visualize the period (tau)? RASTER PLOTS Double, triple etc. raster plots Modulo tau raster plots

11. SLEEP-WAKE RHYTHM IN HUMAN: LD & LL Variability in sleep onset has meaning

12. CIRCADIAN LEAF MOVEMENT RHYTHM

13. BACTERIAL COLONIES EXPRESSING BIOLUMINESCENCE NIGHT PHASE DAY PHASE

14. BACTERIAL LUCIFERASE as a REPORTER of a CIRCADIAN RHYTHM of GENE EXPRESSION in BACTERIA KONDO, STRAYER,KULKARNI, TAYLOR, ISHIURA, GOLDEN & JOHNSON, 1993

15. CIRCADIAN PHOTOACCUMULATION IN PARAMECIUM Hasegawa et al.

16. The clock controls an overt developmental rhythm in Neurospora. movie courtesy of Van Gooch

17. DROSOPHILA PERIOD GENE: FIRST CLOCK MUTANTS WILD TYPE per + ARHYTHMIC per o SHORT PERIOD per S LONG PERIOD per L NOTE: SLOPE is a MEASURE of PERIOD (tau)

18. CIRCADIAN CLOCKS TIMING MAY BE VERY PRECISE DECOURSEY, 1961

19. SLEEP-WAKE RHYTHM IN HUMAN: LD & LL Variability in sleep onset has meaning

20. NIGHT HAULING by ANDREW WYETH showing BIOLUMINESCENCE

21. DINOFLAGELLATE BIOLUMINESCENCE (Hastings’Lab)

22. GONYAULAX CELL AT DAY (LEFT) AND NIGHT PHASE FLUORESCENCE OF LUCIFERIN IN SCINTILLONS

23. DINOFLAGELLATE FLASH & GLOW BIOLUMINESCENCE and its CIRCADIAN EXPRESSION scale: ~ 24 hours peak to peak

24. CIRCADIAN RHYTHM of LUMINESCENCE: top, LD; below, LL LD DD

25. GONYAULAX PEAK TIMES OF GLOW UNDER ENTRAINED AND FREE RUNNING CONDITIONS

26. Academic Press, New York, 1970 View 1: Environmental signals detected by organisms Provide information on time of day View 2: Organisms have internal biological clocks

27. THE BIOLOGICAL CLOCK POSTULATED CELLULAR MECHANISM RESPONSIBLE FOR DAILY RHYTHMS CIRCADIAN RHYTHMS CIRCADIAN CLOCK To be called circadian the organism must be kept under constant conditions CIRCA-: ABOUT -DIAN: ONE DAY Other circa- periodicities CIRCALUNAR: ~MONTHLY CIRCANNUAL: ~YEARLY

28. FUNCTIONS OF THE CIRCADIAN CLOCK Origin and Evolution of Circadian Rhythms TIME ACTIVITIES TO CERTAIN TIMES OF DAY OR NIGHT - Insect eclosion, Drosophila (temperature compensation) - Plant rhythms, flower openings, bee visitations - Cyanobacteria, photosynthesis by day, nitrogen fixation by night CELESTIAL NAVIGATION - Animal migration, sun compass; knowledge of time of day required PHOTOPERIODISM: MEASURE DURATION OF DAY AND NIGHT - Plant rhythms: seasonal flowering, spring summer or fall - Animal seasonal reproduction; hamster only once per year

29. CIRCADIAN RHYTHMS - KEY PROPERTIES (1)RHYTHMS CONTINUE IN THE ABSENCE OF LIGHT/DARK CYCLES WITH PERIODS CLOSE TO BUT NOT EXACTLY 24H exact period length is a function of environmental conditions (2)TEMPERATURE ALSO AFFECTS CIRCADIAN PERIOD BUT MUCH LESS SO THAN FOR TYPICAL BIOCHEMICAL REACTIONS. Cellular compensation is postulated to be responsible (3)PHASE can be RESET by LIGHT: ENTRAINED or SYNCHRONIZED to DAILY LIGHT / DARK or OTHER ENVIRONMENTAL CYCLES resetting does not need cycles: single exposures or pulses suffice

30. CIRCADIAN CLOCKS TIMING MAY BE VERY PRECISE DECOURSEY, 1961

31. BUT PERIOD VALUES VARY WITHIN & ACROSS SPECIES

32. PERIOD (Tau) DEPENDS on LIGHT INTENSITY

33. EFFECT of LIGHT INTENSITY on Tau in SPARROWS MENAKER, 1969

34. EFFECT of INTENSITY of WHITE LIGHT on PERIOD in DIFFERENT SPECIES

35. EFFECT of INTENSITY on TAU DEPENDS on COLOR of INCIDENT LIGHT Gonyaulax polyedra

36. PERIOD (Tau) of CIRCADIAN RHYTHM DEPENDS on PRIOR L/D CYCLE PERIOD (T=20) MOUSE PITTENDRIGH & DAAN ENTRAINMENT to 20 hr CYCLE MUST be DONE GRADUALLY

37. PERIOD (Tau) of CIRCADIAN RHYTHM DEPENDS on PERIOD (T=28) OF PRIOR L/D CYCLE MOUSE PITTENDRIGH & DAAN ENTRAINMENT to 28 hr CYCLE MUST be DONE GRADUALLY

38. MOUSE: AFTER EFFECTS ON PERIOD PITTENDRIGH & DAAN

39. DRUGS MAY ALSO HAVE an EFFECT ON PERIOD e.g., PROTEIN PHOSPHATASE INHIBITORS

40. PROTEIN KINASE INHIBITORS AFFECT PERIOD

41. CIRCADIAN RHYTHMS - KEY PROPERTIES (1)RHYTHMS CONTINUE IN ABSENCE OF LIGHT / DARK CYCLES WITH PERIODS CLOSE TO BUT NOT EXACTLY 24 HOURS exact period length is a function of environmental conditions (2)TEMPERATURE ALSO AFFECTS CIRCADIAN PERIOD BUT MUCH LESS SO THAN FOR TYPICAL BIOCHEMICAL REACTIONS. Cellular compensation is postulated to be responsible. THIS GAVE RISE TO THE CLOCK IDEA (3)PHASE can be RESET by LIGHT: ENTRAINED or SYNCHRONIZED to DAILY LIGHT / DARK or OTHER ENVIRONMENTAL CYCLES resetting does not need cycles: single exposures or pulses suffice

42. TEMPERATURE HAS ONLY SMALL EFFECT ON PERIOD

43. PHOTOACCUMULATION IN EUGLENA Bruce & PIttendrigh,1956

44. GONYAULAX TEMPERATURE COMPENSATION Hastings and Sweeney, 1957

45. TEMPERATURE EFFECT on TAU in GONYAULAX

46. TEMPERATURE-COMPENSATED CIRCADIAN PERIOD IN VARIOUS ORGANISMS

47. LOSS OF RHYTHMICITY Several environmental conditions, notably low temperature and bright light, lead to the loss of rhythm; has it stopped or simply not seen? Return to initial conditions results in the rhythm reappearance of at a fixed phase, CT12, no matter when the return occurs

48. LOSS OF RHYTHMICITY BELOW 12 O C

49. LOW TEMPERATURE for 12 hr “ STOPS” the CLOCK for 12 hr

50. “STOPPED” Gonyaulax CLOCK RESTARTS with PHASE at CT12

51. LOSS OF RHYTHMICITY Bright light also leads to the loss of rhythmicity and return to initial conditions causes rhythm to return at a fixed phase, no matter when. Occurs in many different organisms

52. EFFECT of WHITE LIGHT INTENSITY on PERIOD and AMPLITUDE in Gonyaulax 680 fc 380 fc 120 fc

53. JCCP 1957 Fig 3 After an extended period in bright LL, with no detectable bioluminescence rhythm, transfer to DD re-initiates a rhythm. Phase is determined by the time of transfer, as if a stopped clock had restarted

54. RHYTHM in Gonyaulax INITIATED by SHIFT from LL to DD is PHASED STARTING at CT 12

55. ANOTHER EXAMPLE of a CLOCK “STOPPED” in BRIGHT WHITE LIGHT Peterson and Saunders J. Theor Biol 1980 Eclosion rhythm of flesh-fly Sarcophaga argyrostoma. White triangle represents time of light exposure. Each point is the median eclosion time for the culture from the end of the light exposure. Note that the duration between end of light exposure and eclosion is constant (11.5 hrs, dotted line), as if the clock is stopped and restarts when the stimulus ends. Note the slight ~24 hr oscillation around the dotted line.