MCB 186CIRCADIAN BIOLOGY

CIRCADIAN PHOTORECEPTION USES DIFFERENT RECEPTORS and PATHWAYS FROM VISION

October 26, 2005J. W. Hastings

HOW DOES LIGHT ENTRAIN THE CIRCADIAN CLOCK?

Action spectra should reveal the photoreceptor molecules involved

What is the “action”?

Phase shifts; Tau; Amplitude of Rhythms

DOES CIRCADIAN PHOTORECEPTION USE THE SAME MOLECULES AS FOR

OTHER PHOTORESPONSES?

e.g.,PHOTOTAXIS, PHOTOMOVEMENT, VISION

OKAZAKI LARGE SPECTROGRAPH: placing samples

OKAZAKI LARGE SPECTROGRAPH: 1 cm= 1 nm

GONYAULAX ACTION SPECTRUM FOR PHASE SHIFTING BY 3 HOUR LIGHT EXPOSURES

The HORSESHOE CRAB Limulus polyphemus

SEVERAL PAIRS of EYES; ALL PARTICIPATE in CLOCK

PHOTORECEPTION but TELSON (TAIL) RECEPTORS are DOMINANT

THE SEVERAL EYES and MANY

PHOTORECEPTORS of the HORSESHOE CRAB

Limulus

Barlow, Scientific American, April 1990

All receptors have phase shifting effects on circadian rhythm; most effective are those in the tail

Renniger et al.1988 J. Comp.Physiol 162: 127-140

PHASE SHIFTING by LIGHT ONLY to the TAILRenniger et al.1988 J. Comp.Physiol 162: 127-140

Horseshoe Crab Limulus

PHASE RESPONSE CURVE for LIGHT PULSES TO TAIL

Limulus Renniger et al.1988 J. Comp.Physiol 162: 127-140

Chlamydomonas PHOTOTAXIS RHYTHM in constant light KONDO

Replace Vitamin A in Rhodopsin with an analog in Chlamydomonas Foster et al 1984 Nature 311: 756-759

Since the absorption spectra are different the action spectra should differ

CHLAMY ACTION SPECTRA for PHOTOTAXIS with DIFFERENT ANALOGS

Foster et al 1984 Nature 311:756-750

ACTION SPECTRA FOR PHASE SHIFTING IN CHLAMY

KONDO ET AL, 1989

PHASE SHIFTS with DIFFERENT COLORS of LIGHT-CHLAMY

PHASE SHIFTS DIFFER with COLOR of LIGHT in CHLAMY

Drosophila NO EFFECT of NO beta CAROTENE on CIRCADIAN PHOTORECEPTION Zimmerman & Goldsmith Science 1980

EFFECT of LIGHT INTENSITY on TAU in a BLINDED SPARROWM. MENAKER, 1968 PNAS 59: 414-421

BLIND SPARROW IS ENTRAINED BY LIGHT (DIM)

M. Menaker

EYES REMOVED; LIGHT ENTRAINMENT VIA BRAIN (Menaker,1970)

feathers plucked

1. from back

2. from head

3. feathers growing back; replucked

4. India ink under skin on head

5. ink removed

Chlamydomonas PHASE RESPONSE CURVE