biological clock an innate mechanism in living organisms that controls the periodicity or rhythm of...
TRANSCRIPT
Biological clockAn innate mechanism in living organisms that controls the periodicity or rhythm of various physiological functions or activities.
– Circadian rhythm• Circadian: circa(around)+dies(day)
– Ultradian rhythm– Infradian rhythm
Internal biological clock+ change of environment
Reset / entrainment mechanism
Clock-associated genes
• CCA1• LHY• FKF1• ZTL
Environments
• Temperature
• Light– Period– wave
Relationship clock-associated genes and the photoreceptors
ELF3 Encodes a Circadian Clock-Regulated Nuclear Protein That
Functions in an Arabidopsis PHYB Signal Transduction Pathway
elf3
• Defective in light perception or light-mediated signal transduction
• Defective in circadian rhythm responses
wild(C)
elf3-1
elf3-1:cosmid B8
elf3-1:cosmid E11
SD
LDLD
SD
Two types of photoreceptor
• Five red/far-red light-absorbing phytochromes– Phytochrome A[PHYA], PHYB, PHYC,
PHYD, and PHYE
• Two blue/UV-A light-absorbing cryptochromes– CRY1 and CRY2
ELF3
• novel 695 amino acid protein• without any significant homology to
proteins of known function• glutamine/threonine-rich sequence
and nuclear localization signal in the C-terminal region
transcription factor
Fig 1-A. Sequence comparison of ELF3 and putative ELF3 homologs
Cardamine
Arabidopsis
tomatoricemaize
ELF3 function may be conserved between dicots and monocots.
Fig 1-B. ELF3 is a novel nuclear protein.
Fig 2. Accumulation of the ELF3 protein is regulated by light and the circadian clock.
Fig 3-1. ELF3 and PHYB proteins interaction in the Yeast Tow-Hybrid System
Fig 3-2. ELF3 and PHYB proteins interaction in Vitro
PHYB-ELF3 interaction in vivo could regulate aspects of PHYB-mediated photomorphogenesis
Fig 4-A. Hypocotyl length of seedlings grown under dark, white, red, and far-red light condition.
Fig 4-B Flowering time for wild type and mutant plants under LD or SD growth conditions.
Fig 5. Genetic interactions of the ELF3 overexpression(ELF3-OX) line with the phyB mutation