Biological Rhythms

1. Biological Rhythms

2. Biological Rhythms – terms and characteristics Rate of activity Time Amplitude – magnitude of change in the activity Period – time required to complete an entire cycle Phase – any recognizable part of the cycle (e.g. active phase)

3. Biological Rhythms – terms and characteristics 1. Rhythms are temperature-compensated. 2. Unaffected by metabolic poisons or inhibitors 3. Occur with approximately the same frequency as some environmental feature 4. Self-sustaining – maintain cyclicity in absence of cues 5. Can be entrained by environmental cues

4. Types of Rhythms i) Epicycles (Ultradian) Rhythms - cycles of repeated activity that are less than 24 hours Arenicola marina - feed on surface every 6 -8 mins

5. Types of Rhythms i) Epicycles (Ultradian) Rhythms

6. Types of Rhythms ii) Tidal Rhythms - cycles of repeated activity that are synchronized with tidal flow -fiddler crab - times activity cycles to match tidal flow High tide Foraging area

7. Types of Rhythms ii) Tidal Rhythms

8. Types of Rhythms ii) Tidal Rhythms

9. Types of Rhythms iii) Lunar Rhythms - cycles of repeated activity that are synchronized with lunar cycles Emergence is geared to lowest tide Clunio marinus

10. Types of Rhythms iii) Lunar Rhythms - cycles of repeated activity that are synchronized with lunar cycles -spawn between 10 pm and 4 am on the night before a full or new moon California grunion (Leuresthes tenuis)

11. Types of Rhythms iv) Circadian Rhythms - cycles of activity that are repeated approximately every 24 hours

12. Types of Rhythms iv) Circadian Rhythms - cycles of activity that are repeated approximately every 24 hours Crepuscular A c t i v i t y Nocturnal Diurnal Dawn Noon Dusk Midnight Dawn

13. Types of Rhythms v) Circannual Rhythms -rhythms that are approximately 1 year long - hibernation Year 2 Year 3 Year 4

14. Controls of Rhythms Calling by Male Crickets Hypothesis 1: Male cricket possesses an internal timer that measures time since last singing bout. Hypothesis 2: Male cricket is cued to sing by the effect of changing light levels on some control centre in the brain.

15. Controls of Rhythms light dark Calling by Male Crickets Begin at same time light Shift start time light dark Begin at same time

16. Controls of Rhythms light dark Calling by Male Crickets ENTRAINED light FREE-RUNNING light dark ENTRAINED

17. Cricket Calling Rhythm Optic lobe  separate ganglion Subesophageal ganglion Rhythm maintained Rhythm lost

18. In Mammals Suprachiasmatic nucleus

19. In Mammals Suprachiasmatic nucleus Arrhythmic patterns of locomotion, feeding, hormone secretion Remove SCN Implant donor SCN tissue Return rhythms of donor hamster

20. In Mammals Suprachiasmatic nucleus Not the only pacemaker In Rhesus monkeys Loss of activity cycle Maintain body temperature cycle Ablate SCN Ablate Ventromedial hypothalamus Ablate Ventromedial hypothalamus Loss of body temperature cycle

21. General Functioning of Biological Clocks locomotion hormone release Pace-maker Sensory receptors Environmental cues feeding others Clock-setting pathway Clock mechanism Observed behaviour

22. Gonyaulax – Circadian Bioluminescence Night Day

23. Arrhythmic behaviour Day 1 Day 2 Day 3 Naked Mole Rat

24. What is responsible for circadian rhythms in mammals? Pineal gland Pineal eye Regulates rhythms based on photoperiod

25. CIRCADIAN ‘CLOCK’ IN Drosophila CLK CYC per mRNA PER protein tim mRNA TIM protein Effector gene mRNA Effector protein PROMOTER http://www.hhmi.org/biointeractive/clocks/drosophila_clock.html

26. CIRCADIAN ‘CLOCK’ IN Drosophila CLK CYC per mRNA PER protein tim mRNA TIM protein Effector gene mRNA Effector protein PER/TIM dimers PROMOTER move to nucleus dissociate

27. CIRCADIAN ‘CLOCK’ IN Drosophila CLK CYC per mRNA PER protein tim mRNA TIM protein Effector gene mRNA Effector protein PER/TIM dimers PROMOTER move to nucleus dissociate per GENES TURNED OFF tim Effector gene PROMOTER

29. Setting the Clock Light (blue) absorbed by cryptochromes Allosteric change Can bind PER and TIM Breakdown of PER and TIM End of inhibition of transcription

30. CIRCADIAN ‘CLOCK’ IN MAMMALS CLK BMAL1 per mRNA PER protein cry mRNA CRY protein Effector gene mRNA Effector protein PROMOTER per GENES TURNED OFF cry Effector gene PROMOTER

31. Genetic Control of Daily Cycle - per gene mutations 24 hrs Wild type Long-period per gene Arrhythmic Short-period After Baylies et al, 1987

32. Rhythmic Changes in Colour Uca panacea – fiddler crab Light Phase Dark Phase Darnell. 2012 J.Exp.Mar. Biol. Ecol. 427:39

33. Rhythmic Changes in Colour Uca panacea – fiddler crab Light Phase Conflicting demands Communication Dark Phase Thermoregulation Camouflage Darnell. 2012 J.Exp.Mar. Biol. Ecol. 427:39

34. Rhythmic Changes in COlour Uca panacea – fiddler crab Dark Phase Black background, low temperatures Takes precedence Light Phase White background, high temperatures Darnell. 2012 J.Exp.Mar. Biol. Ecol. 427:39

35. Rhythmic Changes in Colour Colour changes via melanophores

36. Rhythmic Changes in Colour Light phase Dark phase Fully concentrated Fully dispersed Darnell. 2012 J.Exp.Mar. Biol. Ecol. 427:39

37. Rhythmic Changes in Colour Darnell. 2012 J.Exp.Mar. Biol. Ecol. 427:39

38. Natural L:D cycle Reversed L:D cycle Reversed L:D cycle (+ 3 days) Darnell. 2012 J.Exp.Mar. Biol. Ecol. 427:39

39. Rhythms in Arctic Breeding Birds Steiger et al. 2013. Proc.Roy,Soc.Lond. 280:

40. Rhythms in Arctic Breeding Birds Semipalmated sandpiper Pectoral sandpiper Red phalarope Lapland longspur Steiger et al. 2013. Proc.Roy,Soc.Lond. 280:

41. Rhythms in Arctic Breeding Birds Semipalmated sandpiper Pectoral sandpiper Red phalarope Lapland longspur Steiger et al. 2013. Proc.Roy,Soc.Lond. 280:

42. Rhythms in Arctic Breeding Birds