Cryptochromes plants

NiNU L, AHMAD M, MiARELLi c, CASHMORE A R and GiULiANO G (1999) Cryptochrome 1 controls tomato development in response to blue light , Plant J, 18, 551-6. 

Folate and FAD are also components of cryptochromes, proteins widespread in living organisms. Cryptochromes are considered photolyase sequence homologues with no DNA repair activities but with blue light-activated factors. Cryptochromes regulate growth and development in plants and seem to be responsible for the synchronization of circadian rhythms in animals and human. ... 

Partch, C. L. et al., Postranslational regulation of mammalian circadian clock by cryptochrome and proteinphosphatase 5, Proc Aarf Acad. Sci. USA, 103, 10467, 2006. Briggs, W.R., Christie, J.M., and Salomon, M., Phototropins a new family of flavinbinding blue light receptors in plants, Antioxid. Redox Signal, 3, 775, 2001. Briggs,W.R. et al.. The phototropin family of photoreceptors. Plant Cell, 13, 993, 2001. 

WADE, H.K., BIBIKOVA, T.N., VALENTINE, W.J., JENKINS, G.I., Interactions within a network of phytochrome, cryptochrome and UV-B phototransduction pathways regulate chalcone synthase gene expression in Arabidopsis leaf tissue, Plant J., 2001, 25, 675-685. 

Ahmad M, Grancher N, Heil M et al 2002 Action spectrum for cryptochrome-dependent hypocotyl growth inhibition in A-rabidopsis. Plant Physiol 129 774—785 Baldwin JM, Schertler GF, Unger VM 1997 An alpha-carbon template for the transmembrane helices in the rhodopsin family of G-protein-coupled receptors. J Mol Biol 272 144—164 Batni S, Scalzetti L, Moody S A, Knox BE 1996 Characterization of the Xenopus rhodopsin gene. J Biol Chem 271 3179-3186... 

Bridges C 1959 The visual pigments of some common laboratory animals. Nature 184 727-728 Burns ME, Baylor DA 2001 Activation, deactivation, and adaptation in vertebrate photoreceptor cells. Annu Rev Neurosci 24 779-805 Cashmore AR, Jarillo JA, Wu Y-J, Liu D 1999 Cryptochromes blue light receptors for plants and animals. Science 284 760-765... 

Sargent ML, Briggs WR, Woodward DO 1966 Circadian nature of a rhythm expressed by an invertaseless strain of Neurospora crassa. Plant Physiol 41 1343—1349 Selby CP, Thompson C, Schmitz TM, Van Gelder RN, Sancar A 2000 Functional redundancy of cryptochromes and classical photoreceptors for nonvisual ocular photoreception in mice. Proc Natl Acad Sci USA 97 14697-14702... 

Kay It is external coincidence. Both are required. If you activate phytochrome A (phjA) and cryptochrome 2 cry 2) in wild-type plants at the end of the day in short days this has no effect on flowering because the phase of CO expression is such that it is at too low a level. It really seems to be entrainment regulating CO waveform. This is where Bunning in the 1940s was brilliant in proposing how this could work. This story will get even prettier when we fulfil the prediction that this light is leading to some post-translational modulation of CO protein or potentially a CO partner. 

Egan ES, Franklin TM, Hilderbrand-Chae MJ et al 1999 An extraretinally expressed insect cryptochrome with similarity to the blue light photoreceptors of mammals and plants. J Neurosci 19 3665-3673... 

Certain flavoproteins act in a quite different role as light receptors. Cryptochromes are a family of flavoproteins, widely distributed in the eukaryotic phyla, that mediate the effects of blue light on plant development and the effects of light on mammalian circadian rhythms (oscillations in physiology and biochemistry, with a 24-hour period). The cryptochromes are homologs of another family of flavoproteins, the photolyases. Found in both prokaryotes and eukaryotes, photolyases use the energy of absorbed light to repair chemical defects inDNA. 

Redox reactions have been proposed to play a key role in light-responsive activities of cryptochromes [98, 99], blue-light photoreceptors in plants, animals, and bacteria with widespread functions ranging from the regulation of circadian rhythms of plants and animals [13] to the sensing of magnetic fields in a number of species... 

In contrast to the paucity of biochemical data on the photosensory functions of cryptochromes, there are extensive genetic and cell biology data on the roles of cryptochromes in blue light, photoreception in plants and animals, and circadian clock regulation in animals (Gashmore, 2003 Lin and Shalitin, 2003 Sancar, 2003). In Arabidopsis, blue light inhibits elongation of hypocotyls in a cryptochrome-dependent manner. In animals. 

Cashmore, A. R. (2003). Cryptochromes enabling plants and animals to determine circadian time. Cell 114, 537-543. 

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