
	Where results make sense

Topic: Cryptochrome

	Clock Photoreceptor Shared By Plants and Animals
		Because cryptochrome is a light-responsive protein in plants, Stanewsky and Hall thought the clock in the fly mutants may be unable to respond to light.
		He and postdoc Yasuhide Miyamoto found cryptochrome in mice in two telling places: the suprachiasmatic nucleus, the brain area that is the seat of the clock in mammals, and in a layer of cells in the retina that is necessary for circadian light responses.
		What's more, Sancar has localized cryptochrome to the cell's nucleus, where other key clock components such as PER and TIM go to regulate their own genes, a function that is at the heart of the clock's oscillating mechanism.
	cas.bellarmine.edu /tietjen/images/clock_photoreceptor_shared_by_pl.htm (1975 words)

	Two Brandeis Scientists Shed Light On The First Photoreceptor Known To Set Circadian Rhythms
		There are two known cryptochromes in humans, Rosbash says; it's possible that these may work in concert with other photoreceptors to reset our biological clocks and those of our closest evolutionary brethren.
		Cryptochrome's penchant for blue light suggests it resets biological clocks at dawn and dusk's dimmest hours, when blue light is most abundant.
		Cryptochrome evidently works on the front lines of circadian rhythms, which operate somewhat like a genetic chain letter linking a plethora of genes that are cyclical in their activity.
	www.eurekalert.org /pub_releases/1998-11/BU-TBSS-231198.php (618 words)

	Cryptochrome (Site not responding. Last check: 2007-11-02)
		Cryptochromes are flavoproteins that share sequence similarities to DNA photolyase (a blue light-dependent DNA repairing enzyme) but show no detectable photolyase activity.
		Cryptochromes have been demonstrated to regulate the circadian clock in both plants and animals.
		We have previously demonstrated that cry2 is a major photoreceptor regulating photoperiodic flowering, that cryptochromes and phytochromes act in three genetic pathways in response to different wavelength of light to regulate floral initiation, and that blue light-dependent cryptochrome phosphorylation is an important reaction associated with cryptochrome function and regulation (link to publications).
	www.mcdb.ucla.edu /Research/Lin/cryptochrome/cryptochrome.html (283 words)

	Presentation #2, Plant Molecular Genetics, Ahad Baghery
		The phytochrome (phy) family, absorbing in the red region of the spectrum, and the cryptochrome (cry) family, absorbing in the blue, both mediate light input to the clock.
		Because cryptochromes show no absorption peak in the red region of the spectrum, cry1 and cry2 may be acting as signal transduction components downstream of phytochrome.
		This indicates that cryptochrome is not essential for the phyA signaling in red light that controls inhibition of hypocotyl elongation.
	home.cc.umanitoba.ca /~umbagher/39.768/P2/P2.html (1414 words)

	HHMI News: Shedding Light on Circadian Rhythms
		Cryptochromes are light-reactive pigments found in the eye and in plants.
		Cryptochrome proteins 1 and 2 (CRY1 and CRY2), which were first discovered in plants, trigger plant growth by responding to light in the blue to ultraviolet part of the spectrum.
		According to Rosbash, these studies show that the role of cryptochrome in circadian function in fruit flies "is simple and uncomplicated, and it lies at the top of the pathway." If cryptochrome does not get light, says Rosbash, the circadian system simply does not work correctly.
	www.hhmi.org /news/takahashi.html (924 words)

	Interactive Fly, Drosophila
		Cryptochromes are members of a large protein family that includes blue light photoreceptors, 6-4 photolyases (DNA photoreactivating enzymes), and microbial Class I CPD (cyclobutane pyrimidine dimers) photolyases.
		Similar to other cryptochromes, DCry has conserved domains that include residues known to be important for the noncovalent binding of the cofactors pterin (folate) and flavin adenine dinucleotide.
		Also like other cryptochromes, the DCry protein has a nonconserved C terminus (of 41 residues) that is completely unrelated to photolyases, cryptochromes, or any other sequence in the protein databases.
	www.sdbonline.org /fly/hjmuller/crypto1.htm (3130 words)

	3 Cryptochromes and Phototropin (Site not responding. Last check: 2007-11-02)
		Cryptochrome was also found to differ from phytochrome in that it shows no photoreversibility and is unable to compare the relative magnitude of two wavelengths, thus being useful only in detecting the quantity and not the quality of light (Morgan and Smith 1981).
		The widely accepted view that plants contain only two forms of cryptochrome was altered in 2001 when Perrotta et al, produced evidence that tomato and barley contain a third cryptochrome gene, thought to have arisen from independent duplications of CRY 1, and consequently named CRY 1b.
		From cryptochrome homology with DNA photolyase it has been suggested that signal transduction could be initiated by an electron transfer to a specific redox sensitive partner (Christie and Briggs 2001), although no interacting protein has been found.
	www.shef.ac.uk /aps/apsrtp/thomas/3-0.htm (1001 words)

	Dr. Aziz Sancar
		We have discovered that a flavoprotein called cryptochrome, closely related to the light-dependent DNA repair enzyme photolyase, regulates the mammalian circadian clock by light-independent and light-dependent mechanisms.
		Currently, we are investigating the action mechanism of cryptochrome using biophysical methods including femtochemistry, biochemical methods, and neurobiological methods including mice activity profiles.
		In addition, we are investigating the connection between the circadian cycle and the cell cycle checkpoints and how disruption of the circadian cycle might affect the susceptibility of mice and humans to cancers.
	www.med.unc.edu /biochem/sancara.htm (512 words)

	CEA - Life Science Division -
		Cryptochrome – a blue light photoreceptor with strong sequence homology to photolyase
		A closely related subject is the study of the photoreactions of cryptochrome blue light photoreceptors in plants and animals.
		Cryptochromes are flavoproteins with an amino acid sequence similar to photolyases, but without DNA repair activity.
	www-dsv.cea.fr /content/cea_eng/d_dep/d_dbjc/d_sbe/d_lpp/brettel_an.htm (836 words)

	UPenn - SAS - Biology - People - Faculty
		Interest in this photoreceptor has recently been heightened by the finding that related cryptochrome photoreceptors are responsible for the entrainment of circadian rhythms in animals, including humans.
		Ahmad, M. and Cashmore, A. The blue-light receptor cryptochrome 1 shows functional dependence on phytochrome A or phytochrome B in Arabidopsis thaliana.
		Lin, C., Ahmad, M. and Cashmore, A. Arabidopsis cryptochrome 1 is a soluble protein mediating blue light-dependent regulation of plant growth and development.
	www.bio.upenn.edu /faculty/cashmore (473 words)

	Researchers identify 'light meter' that controls pupil constriction
		In that nonvisual pathway, melanopsin is thought to play the dominant role in synchronizing the mouse's internal circadian clock to external light and dark cycles.
		In these experiments, however, Van Gelder, and his research team demonstrated that the constriction of the pupil in the chick eye seems to be regulated by cryptochrome rather than melanopsin, Melanopsin is part of the family of proteins, called opsins, that mediate normal visual function.
		When cryptochrome protein production was blocked by 50 percent, the researchers observed a corresponding 50 percent loss of sensitivity to light.
	www.eurekalert.org /pub_releases/2004-09/wuso-ri092904.php (764 words)

	Circadian Control of the Cell Cy (Site not responding. Last check: 2007-11-02)
		Cryptochromes are blue-light receptors found in bacteria, plants and animals.
		Phylogenetic analysis of the photolyase/blue light receptor gene family shows that the K.brevis cryptochrome falls within the cryptochrome DASH clade and not the photolyase, cryptochrome 1 or cryptochrome 2 clades.
		Other classes of cryptochromes have been shown to be under circadian control, with rhythmic oscillations in gene expression.
	www.musc.edu /mbes/SROH05/abstracts/brunelle.html (405 words)

	CRYPTOCHROME BLUE LIGHT RECEPTORS: FUNCTION AND SIGNAL TRANSDUCTION
		Cryptochrome is the photolyase-like blue/UV-A light receptors found in plants and animals.
		Guo, H., Duong, H., Ma, N., and Lin, C. (1999) The Arabidopsis blue-light receptor cryptochrome 2 is a nuclear protein regulated by a blue light-dependent post-transcriptional mechanism.
		Mockler, T. C., Guo, H., Yang, H., Duong, H., and Lin, C. (1999) Antagonistic actions of the Arabidopsis cryptochromes and phytochrome B in the regulation of floral induction.
	ag.arizona.edu /pls/seminars/linabs.htm (215 words)

	Direct Interaction of Arabidopsis Cryptochromes with COP1 in Mediation of Photomorphogenic Development -- Wang et al., ... (Site not responding. Last check: 2007-11-02)
		Here we show that both photo-activated cryptochromes repress COP1 activity through a direct protein-protein contact, and that this direct regulation is primarily responsible for the cryptochrome-mediated blue light regulation of seedling photomorphogenic development and genome expression profile.
		Cryptochrome 1 Contributes to Blue-Light Sensing in Pea.
		Cryptochrome Light Signals Control Development to Suppress Auxin Sensitivity in the Moss Physcomitrella patens.
	intl.sciencemag.org /cgi/content/abstract/1063630v1 (1022 words)

	Functional redundancy of cryptochromes and classical photoreceptors for nonvisual ocular photoreception in mice -- ...
		The response of the mutant mouse to photic input was
		and mCry2 genes in the mouse retina, it was proposed that cryptochromes
		that the cryptochromes are not necessary for behavioral masking.
	www.pnas.org /cgi/content/full/97/26/14697 (4580 words)

	DOCUMENT LISTING FOR:
		The cryptochrome family of flavoproteins function in photic entrainment of insects and plants.
		When compounded with the rd/rd mutation, loss of cryptochrome function leads to marked loss of photic sensitivity for behavioral masking.
		These results suggest a pleotropic role for cryptochromes in the mammalian circadian timekeeping system, functioning both within the clock mechanism, and on the photic input pathway.
	www.kumc.edu /POL/ASP_Home/Meetings/Annual2002/Sunday/D1.html (1795 words)

	ScienceDaily: Scientists Find Eye Pigment Controls Circadian Rhythm
		Discovered in 1877, pigments known as opsins, which are linked to vitamin A and located in the retina, enable mammals to see by absorbing light and transferring visual signals through the optic nerve to the brain, Sancar explained.
		The newly discovered cryptochromes, which come in two forms called CRY 1 and CRY 2, are linked to vitamin B-2 and located in a different part of the retina.
		Cryptochromes enable animals and humans to synchronize their circadian clock by absorbing blue light and transferring the light signal through the optic nerve to a different part of the brain from the center for vision.
	www.sciencedaily.com /releases/1998/05/980528065651.htm (2073 words)

	Washington University Neuroscience
		Now investigators at Washington University School of Medicine in St. Louis have demonstrated in chickens that a protein called cryptochrome plays a key role in that reflex.
		In the mouse, the meter is located in the retina and primarily uses melanopsin to do its work with cryptochrome proteins amplifying the signal.
		“If we could learn how cryptochrome is making the pupil respond to light, we might be able to make other cells respond to light, even in systems that are not visual.
	thalamus.wustl.edu /neuroweb/home/whatsnew11.html (627 words)

	HHMI News: Researchers Identify Unique Circadian Rhythm Photoreceptor
		Michael Rosbash and Jeffrey Hall at Brandeis University, however, there is a strain of mutant flies that maintains a steady clock when barraged with intense light.
		Experiments by Rosbash and his colleagues now indicate that the fly cryptochrome dCRY is perhaps the only photoreceptor molecule through which light regulates the fly's circadian rhythm, the near-universal 24-hour biological clock that governs sleep and wakefulness, rest and activity, body temperature, cardiac output, and many other functions.
		Mammalian cryptochrome molecules appear to be involved in the central clockwork mechanism, rather than in light-detection, he said.
	www.hhmi.org /news/rosbash.html (694 words)

	Regulation of the Mammalian Circadian Clock by Cryptochrome -- Sancar 279 (33): 34079 -- Journal of Biological Chemistry
		and hence it was assumed to be the elusive "cryptochrome" and
		Effect of cryptochrome mutation on the circadian behavior of mice (35, 37).
		The light signal received by both the rods and cones in the outer retina and by the cryptochromes and melanopsin in the inner retina (front) is transmitted to the master circadian clock, the SCN, by a specialized group of retinal ganglion cells constituting the retinohypothalamic tract (red) (4, 5).
	www.jbc.org /cgi/content/full/279/33/34079 (3718 words)

	Regulation of Flowering Time by Arabidopsis Photoreceptors -- Guo et al. 279 (5355): 1360 -- Science
		Antagonistic actions of Arabidopsis cryptochromes and phytochrome B in the regulation of floral induction.
		Cryptochrome Nucleocytoplasmic Distribution and Gene Expression Are Regulated by Light Quality in the Fern Adiantum capillus-veneris.
		Phytochromes and Cryptochromes in the Entrainment of the Arabidopsis Circadian Clock.
	www.sciencemag.org /cgi/content/abstract/279/5355/1360 (1626 words)

	Phytochrome and Cryptochrome Functions in Crop Plants (Site not responding. Last check: 2007-11-02)
		Light is perceived and its developmental effects mediated by two important families of photoreceptor proteins: the phytochromes, which predominantly absorb red (R) and far-red light (FR), and the cryptochromes, which primarily absorb blue light (B).
		Most recent progress in understanding the roles of these photoreceptors in plant development has come from studies in Arabidopsis thaliana, although phytochrome and cryptochrome functions are also being explored by a genetic approach in other model species including tomato, pea, and rice.
		However, the fact that these species differ in growth habit, physiology, and photoreceptor complement means that they offer a broader perspective on photoreceptor function and how genes controlling photoreceptor function might be useful for modifying specific traits in a diverse range of crop plants.
	www.dekker.com /sdek/22091738-10361607/abstract~db=enc~content=a713575945~words= (316 words)

	Steve's place - Photomorphogenesis
		Much of the current work on photomorphogenesis is done on Arabidopsis thaliana (thale-cress), the 'botanists' fruit-fly, particularly in the analysis of mutants that re unable to respond to light such as nph (non-phototropic hypocotyl).
		The second main blue light receptor in plants is cryptochrome, which modulates the phytochrome response.
		the mechanism of the HIR appears to be mediated by phytochrome and cryptochrome acting together.
	www.steve.gb.com /science/photomorphogenesis.html (1605 words)

	Circadian Photoreception in Humans and Mice -- Kavakli and Sancar 2 (8): 484 -- Molecular Interventions
		The cryptochromes CRY1 and CRY2 are expressed in the INL and GCL, and melanopsin is expressed in a small fraction of ganglion cells.
		analogous to the cryptochromes of Arabidopsis (28, 37, 44).
		Differential regulation of mammalian period genes and circadian rhythmicity by cryptochromes 1 and 2.
	molinterv.aspetjournals.org /cgi/content/full/2/8/484 (4907 words)

	Cryptochrome Light Signals Control Development to Suppress Auxin Sensitivity in the Moss Physcomitrella patens -- ...
		Cryptochrome Light Signals Control Development to Suppress Auxin Sensitivity in the Moss Physcomitrella patens -- Imaizumi et al.
		Devlin, P.F., and Kay, S.A. Cryptochromes are required for phytochrome signaling to the circadian clock but not for rhythmicity.
		Somers, D.E., Devlin, P.F., and Kay, S.A. Phytochromes and cryptochromes in the entrainment of the Arabidopsis circadian clock.
	www.plantcell.org /cgi/content/full/14/2/373 (7274 words)

	Plant Gene Register PGR99-110 (Site not responding. Last check: 2007-11-02)
		Surprisingly, it has also been shown very recently that the cryptochromes identified in fruit flies and mice are photoreceptors for circadian rhythms and play important roles in maintaining their internal clocks (Stanewsky et al., 1998; van der Horst et al., 1999).
		These findings lead us to conclude that cryptochromes, which were first identified in plants, are a diverse family of photoreceptors throughout the plant and animal kingdoms.
		Isolation of cryptochromes from various species will be necessary if we are to understand the evolutionary history of this ubiquitous photoreceptor.
	www.tarweed.com /pgr/PGR99-110.html (1148 words)

	A blue light receptor cryptochrome 2 and plant development. (Site not responding. Last check: 2007-11-02)
		Plant red/far red-light receptors phytochromes and blue/UV-A light receptors cryptochromes are photoreceptors that mediate light-regulated growth and development of plants.
		It is known that both phytochromes and cryptochromes are required for seedling development.
		Further analysis of different mutations defective in genes encoding different photoreceptors suggests a model to explain the functional interactions of the phytochromes and cryptochromes in the regulation of floral initiation of plants.
	abstracts.aspb.org /pb1998/04/0923.shtml (359 words)

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