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	Phytochrome - Wikipedia, the free encyclopedia
		The phytochrome chromophore is usually called phytochromobilin, and is closely related to phycobilin (the chromophore of the phycobiliproteins used by cyanobacteria and red algae to capture light for photosynthesis) and to the bile pigment bilirubin (whose structure is also affected by light exposure, a fact exploited in the phototherapy of jaundiced newborns).
		The phytochrome pigment was identified using a spectrophotometer in 1959 by biophysicist Warren Butler and biochemist Harold Siegelman.
		Presumably plant phytochromes are derived from an ancestral cyanobacterial phytochrome, perhaps by gene migration from the chloroplast to the nucleus.
	en.wikipedia.org /wiki/Phytochrome (1036 words)

	Phytochrome
		Phytochrome proteins occur as a dimer of two 124 kDa polypeptides, each with a covalently-attached pigment molecule.
		Phytochrome B (PhyB) is probably the photoreceptor involved in shade detection and avoidance.
		Phytochrome C (phyC) is a low-abundance member of the five-membered phytochrome family of photoreceptors in Arabidopsis.
	www.mobot.org /jwcross/duckweed/phytochrome.htm (1393 words)

	Botany online: Plant Responses - Light - Photomorphogenesis, Phytochrome (Site not responding. Last check: 2007-10-13)
		Since the phytochrome type I is encoded by phyA genes is it also termed phytochrome A. In contrast is the type II phytochrome rather heterogeneous.
		Phytochrome has been localized within the cell plasma, the nucleus and the plastids by indirect immunofluorescence.
		He could thus show that the phytochrome of the cells he studied was localized at the cell’s periphery (most likely within the plasmalemma) and was oriented in a certain way.
	www.biologie.uni-hamburg.de /b-online/e30/30b.htm (1765 words)

	Phytochrome: Facts and details from Encyclopedia Topic (Site not responding. Last check: 2007-10-13)
		Phytochrome is a plant pigment pigment quick summary:
		Phytochrome is involved in many other plant responses besides flowering of the plant.
		Phytochrome was isolated in 1959 by a group of scientists working at ARS’s Pioneering Research Laboratories.
	www.absoluteastronomy.com /encyclopedia/p/ph/phytochrome.htm (1248 words)

	ARS Research Timeline - Story on Phytochrome, Other Light Research (Site not responding. Last check: 2007-10-13)
		Skeptics, who reasonably believed phytochrome an illusion, dubbed it a pigment of the imagination.” Ironically, imagination was the key to unveiling phytochrome.
		Continuing phytochrome studies at the Beltsville (Maryland) Agricultural Research Center, plant physiologist Steve Britz measures horizontal light flux in a soybean canopy with a quantum sensor to assess the effects of shading.
		Phytochrome, which had once referred to all visible plant pigments, now named a dual-form protein—green in its red-sensitive form, blue when sensitive to far-red.
	www.ars.usda.gov /is/timeline/light.htm (2652 words)

	Ceratodon phytochrome
		Phytochrome is synthesised in its Pr form, which photoconverts with red light around 660 nm into the thermostable, physiologically-active Pfr form.
		Phytochrome controlled phototropism is now known for protonemata of other ferns including Adiantum capillus-veneris and for protonemata of mosses including Physcomitrella patens and Ceratodon purpureus.
		According to this model phytochrome molecules are located in close vicinity to the plasmalemma with transition dipole moments at a particular orientation with respect to the cell surface.
	www.biologie.fu-berlin.de /lampart/cerpu.html (754 words)

	Ultrafast Dynamics of Phytochrome from the Cyanobacterium Synechocystis, Reconstituted with Phycocyanobilin and ...
		Raman spectroscopic and light-induced kinetic characterization of a recombinant phytochrome of the cyanobacterium Synechocystis.
		Fluorescence and photochemistry of recombinant phytochrome from the cyanobacterium Synechocystis.
		Light-induced proton release and proton uptake reactions in the cyanobacterial phytochrome Cph1.
	www.biophysj.org /cgi/content/full/82/2/1004 (6512 words)

	Phytochrome A overexpression in transgenic tobacco. Correlation of dwarf phenotype with high concentrations of ... (Site not responding. Last check: 2007-10-13)
		Phytochromes are a family of related chromoproteins that regulate photomorphogenesis in plants.
		Ectopic overexpression of the phytochrome A in several plant species has pleiotropic effects, including substantial dwarfing, increased pigmentation, and delayed leaf senescence.
		In transgenic seedlings, high concentrations of oat phytochrome A were detected in stem and petiole vascular tissue (consistent with the activity of the CaMV 35S promoter), implicating vascular tissue as a potential site of phytochrome A action.
	www.biotech-info.net /phytochromeA_tobacco.html (264 words)

	Brazilian Archives of Biology and Technology - Phytochrome controls achene germination in Bidens pilosa L. (Asteraceae) ... (Site not responding. Last check: 2007-10-13)
		Phytochrome controls germination by three distinct mechanisms: very low fluence response (VLFR) characterized by high sensitivity of seeds due to the several environmental factors; low fluence response (LFR) with characteristical photoreversibility and high irradiance response (HIR) where white light can both promote or inhibit germination depending on the fluences (Mancinelli, 1994).
		Fenner (1980) observed that the light requirement is dependent on the conditions of achenes maturation and drying, indicating that because shade light induced light requirement, phytochrome was present and control germination.
		Because the processes controlled by phytochrome under VLFR were very sensitive, dim green safe light currently used to monitor germinated seeds had light fluence enough to sature phytochrome controlled germination (Kendrick and Cone, 1985).
	www.scielo.br /scielo.php?script=sci_arttext&pid=S1516-89132001000200002&lng=en&nrm=iso (1197 words)

	Plant Physiology Online: Phytochrome Effects on Ion Fluxes
		Although the effect is rapid, it is not instantaneous, and it is therefore unlikely to be due to a direct effect of phytochrome on the membrane.
		Instead, phytochrome acts indirectly via one or more signal transduction pathways, as in the case of the regulation of gene expression by phytochrome.
		These findings led some workers to suggest that membrane-bound phytochrome represents the physiologically active fraction, and that all the effects of phytochrome on gene expression are initiated by changes in membrane permeability.
	www.plantphys.net /article.php?ch=t&id=60 (944 words)

	Phytochrome Bot 415 (Site not responding. Last check: 2007-10-13)
		Phytochromes are soluble chromo-proteins (molecular mass: 120 to 127 kD polypeptide).
		Phytochrome distribution within tissues and cells: highest in growing regions.
		Phy B, C, D and E: are light-stable and are the primary phytochromes for red-light responses in light-grown plants.
	www.msu.edu /~janoudi/Phytochrome.htm (266 words)

	NDPK2 as a Signal Transducer in the Phytochrome-mediated Light Signaling -- Shen et al. 280 (7): 5740 -- Journal of ...
		with phytochromes, the biochemical mechanisms remain to be elucidated.
		Phytochrome absorbance at 730 nm was recorded as Pfr components of the phytochrome mixture.
		The phytochrome-binding region affected by the interaction with phytochrome is shown with arrows (modified from Ref. 36).
	www.jbc.org /cgi/content/full/280/7/5740 (5816 words)

	Phytochrome
		Phytochrome is the photoreceptor that activates the de-etiolation (and many other) responses to red light
		Phytochrome is a protein with a pigment molecule covalently bound
		Phytochrome allows the plant to detect properties of light "color" related to growth conditions
	www.esf.edu /efb/course/EFB530/lectures/phytochr.htm (605 words)

	Photoperiodism in Hostas
		Photoreceptors know as phytochromes (of which two types exist in cells of plant) are blue-green proteinaceous pigments which have the capacity to either inhibit flowering or help initiate flowering.
		In the mixture of phytochrome red and phytochrome far-red within plant cells, the relative amounts of each substance, though minute, determine whether the plant will flower or not.
		During the short night phytochrome far-red is changed to phytochrome red, but because the night is short, there is little time with no phytochrome far-red present, therefor the plant flowers rather than being inhibited from flowering.
	www.perennialweb.com /pwarticles/pwphoto-a.html (1771 words)

	Research Page
		Members of the phytochrome family of plant photoreceptors, which can exist in two photochemically interconversible forms (Pr and Pfr) and are involved in regulation of plant development and growth, play important roles in regulating clock activities.
		Therefore, CCA1 appears to be a key element in the functioning of the phytochrome signal transduction pathway leading to increased transcription of this Lhcb gene in Arabidopsis.
		CCA1 is a Myb-related transcription factor that is important for the phytochrome regulation of light-harvesting chlorophyll protein genes (Lhcb or CAB genes) [Wang ZY, Kenigsbuch D, Sun L, Harel E, Ong MS, Tobin EM.
	www.mcdb.ucla.edu /Research/Tobin/research.html (880 words)

	Quail Lab Research
		The photoreceptor molecule functions as a biological switch that, upon perception of the light signal, triggers changes in transcription which are detectable within 5 minutes of the stimulus.
		to examine the phytochrome molecule for clues to its photosensory function and mechanism of action using structural analysis, phytochrome-defective mutants and overexpression of mutagenized phytochromes in transgenic Arabidopsis.
		The discovery of a potentially direct signaling pathway from phytochrome molecules to photoresponsive nuclear genes, by virtue of the molecular cloning of a phytochrome binding protein, PIF3, and its identification as a member of the basic helix-loop-helix superfamily of transcriptional regulators.
	www.pgec.usda.gov /Quail/PQlab.html (236 words)

	Feedback Inhibition of Chlorophyll Synthesis in the Phytochrome Chromophore-Deficient aurea and yellow-green-2 Mutants ...
		Sharma R, Lopez-Juez E, Nagatani A, Furuya M (1993) Identification of photo-inactive phytochrome A in etiolated seedlings and photo-active phytochrome B in green leaves of the aurea mutant of tomato.
		Terry MJ, Kendrick RE (1996) The aurea and yellow-green-2 mutants of tomato are deficient in phytochrome chromophore synthesis.
		Terry MJ, McDowell MD, Lagarias JC (1995) (3Z)- and (3E)-Phytochromobilin are intermediates in the biosynthesis of the phytochrome chromophore.
	www.plantphysiol.org /cgi/content/full/119/1/143 (6283 words)

	Matthew Terry - Research
		Ryberg, M. and Terry, M.J. (2002) Analysis of protochlorophyllide reaccumulation in the phytochrome chromophore-deficient aurea and yg-2 mutants of tomato by in vivo fluorescence spectroscopy.
		Plant J. Terry, M.J. and Kendrick, R.E. The aurea and yellow-green-2 mutants of tomato are deficient in phytochrome chromophore synthesis.
		Terry, M.J., McDowell, M.T. and Lagarias, J.C.)- and (3E)-phytochromobilin are intermediates in the biosynthesis of the phytochrome chromophore.
	www.soton.ac.uk /%7Emjt/refns.html (672 words)

	Phytochrome photoreceptors mediate plasticity to light quality in flowers of the Brassicaceae -- Weinig 89 (2): 230 -- ...
		Casal J. Smith 1988 The loci of perception for phytochrome control of internode growth in light-grown mustard: promotion by low phytochrome photoequilibria in the internode is enhanced by blue light reaching the leaves.
		Clack T. Mathews R. Sharrock 1994 The phytochrome apoprotein family in Arabidopsis is encoded by five genes: the sequences and expression of PHYD and PHYE.
		Johnson E. Bradley N. Harberd G. Whitelam 1994 Photoresponses of light-grown phyA mutants of Arabidopsis: phytochrome A is required for the perception of daylength extensions.
	www.amjbot.org /cgi/content/full/89/2/230 (3650 words)

	Tilman Lamparter Berlin Phytochrome Internet Site
		Phytochromes are photoreceptors that were originally discovered in plants, but are now known to be wider distributed.
		Phytochromes are different from most other photoreceptors, because they exist in two light-interconvertible stable forms (other photoreceptors usually have one stable form).
		This soil bacterium is well known among plant scientists because it can be used as shuttle for transforming DNA into plants (try this movie).
	www.biologie.fu-berlin.de /lampart (421 words)

	Light-induced global structural changes in phytochrome A regulating photomorphogenesis in plants -- Nakasako et al. 272 ... (Site not responding. Last check: 2007-10-13)
		Yeh K-C and Lagarias JC (1998) Eukaryotic phytochromes: light-regulated serine/threonine protein kinases with histidine kinase ancestry.
		Nakazawa M, Yoshida Y and Manabe K (1991) Differences between the surface properties of the Pr and the Pfr forms of native pea phytochrome, and their application to a simplified procedure for purification of the phytochrome.
		Remberg A, Ruddat A, Braslavsky SE, Gärtner W and Schaffner K (1998) Chromophore incorporation, Pr to Pfr kinetics, and Pfr thermal reversion of recombinant N-terminal fragments of phytochrome A and B chromoproteins.
	content.febsjournal.org /cgi/content/full/272/2/603 (4435 words)

	SPA1, a WD-Repeat Protein Specific to Phytochrome A Signal Transduction -- Hoecker et al. 284 (5413): 496 -- Science
		Phytochrome B binds with greater apparent affinity than phytochrome A to the basic helix-loop-helix factor PIF3 in a reaction requiring the PAS domain of PIF3.
		GIGANTEA is a nuclear protein involved in phytochrome signaling in Arabidopsis.
		Sequential and coordinated action of phytochromes A and B during Arabidopsis stem growth revealed by kinetic analysis.
	www.sciencemag.org /cgi/content/abstract/284/5413/496 (1320 words)

	Plant Gene Register PGR96-067 (Site not responding. Last check: 2007-10-13)
		Phytochrome, a family of photochromic photoreceptors probably ubiquitous in green plants, exists in vivo as a cytosolic dimer of two ca.
		The paradox possibly masks critical information regarding the mechanism of phytochrome action: we are therefore investigating the phytochrome system in protonemata of the leafy moss Ceratodon purpureus, a species well-suited to photobiological studies.
		Conservation at the nucleotide level between Physcomitrella phytochrome and the CP2 CDS is 85% once gaps are inserted for two codon deletions in the N- terminus of the Ceratodon gene: two apparently recent local frame-shifts are apparent (475..489 and 3648..3657 in CP2).
	www.tarweed.com /pgr/PGR96-067.html (1253 words)

	Seed Germination Part 2 (Site not responding. Last check: 2007-10-13)
		Phytochrome is a pigment that absorbs light energy.
		On the other hand, if we shine far-red light on imbibing seeds, then virtually all of the phytochrome in the seeds is converted to the Pr form and none of the seeds will germinate.
		Thus phytochrome and light tell lettuce seeds when they are exposed to sunlight and can begin to germinate.
	koning.ecsu.ctstateu.edu /seedg/seed10.html (495 words)

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