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SUMMARY:Forward and reverse genetic identification of mutants linking [Ca2
 +]cyt to the Arabidopsis thaliana circadian clock - Timothy Hearn
DTSTART:20140619T153000Z
DTEND:20140619T160000Z
UID:TALK51416@talks.cam.ac.uk
CONTACT:Megan Cooper
DESCRIPTION:The plant circadian system consists of a network of input sign
 als\, output rhythms and a molecular clock\, which interact to create a ro
 bust oscillator. This oscillator fine tunes biological processes to maximi
 se plant fitness\, and is therefore of great interest to modify to create 
 stress tolerant crops. Previous work has shown that circadian oscillations
  of cytosolic calcium ([Ca2+]cyt) form both an output and an input into th
 e oscillator\, and are inhibited by the small metabolite nicotinamide. Thi
 s is likely to be due to inhibition of an ADP-ribosyl cyclase\, which prod
 uces the calcium mobilising agent cyclic adenosine diphosphate ribose (cAD
 PR). Nicotinamide has also been shown to inhibit poly-ADP ribose polymeras
 es (PARPs)\, and SIRTUINs\, a class of NAD-dependent histone deacetlyases.
  In mammals both PARPS and SIRTUINs have been shown to regulate the amplit
 ude of the circadian clock\, whereas mutation of the mammalian ADPRcyclase
  CD38 lengthens clock period. In addition to abolition of [Ca2+]cyt oscill
 ations nicotinamide also causes both period lengthening and amplitude damp
 ening of other circadian outputs in Arabidopsis. This period effect is tho
 ught to represent the role of [Ca2+]cyt in entraining the circadian clock.
  In this talk I will present the results from a forward genetic screen sho
 wing that we have been able to genetically dissect the period and amplitud
 e effects of nicotinamide from one another. Further we find that only peri
 od mutants have disrupted circadian [Ca2+]cyt oscillations and cADPR media
 ted signalling. These results provide the first genetic tools for investig
 ating the relationship between cADPR mediated [Ca2+]cyt signalling and the
  circadian clock.
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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