Photocontrol of phycoerythrin formation in the blue-green alga Tolypothrix tenuis growing in the dark

Phycoerythrin (PE) formation induced by short fluorescent illumination(15 min, day-light type) was studied with the blue-green algaTolypothrix tenuis growing heterotrophically in the dark. Tolypothrix tenuis grown in the dark contains phycocyanin (PC)and allophycocyanin (APC) but not PE (9, 16). When cells growingexponentially in the dark were illuminated for a short period,PE was formed in the subsequent dark period. PE formation hada 3- to 5-hr lag period then occurred almost linearly for 15to 20 hr until the formation slowed down and the PE contentreached a maximum level. Further incubation generally causeda very slow decrease in PE content. Kinetic analysis indicated that the amount of PE formed afterone short illumination was as large as 35% of the amount ofPE plus PC present in the cells just after illumination. Undera previously proposed hypothesis that PE/PC formation is controlledby the photochemical conversion between PE and PC precursors(10), the present result indicates that the photoreactive precursorshould be present in algal cells in an amount more than 30%of the total phycobilin content, and thus a marked absorptionchange would be expected to occur upon photoconversion of theprecursor. However, the size of spectral changes occurring underthe conditions for photoconversion was only 5% of the expectedvalue. This discrepancy excludes the feasibility of the hypothesisof a photoreactive precursor. (Received June 22, 1977; )     

On the Relationship between Photocontrol of Phycoerythrin Formation and Photoreversible Pigment of Scheibe

Dose-response of photocontrolled phycobiliprotein formationwas studied with two types of Tolypothrix tenuis cells havingdifferent content of photoreversible pigment (PRP) of Scheibe[cf. Scheibe (1972) Science 176: 1037]. PRP was not detectablein cells grown in a medium rich in nitrogen source under weakred light (normal cells) while the content was much larger (morethan 10 times) in cells incubated in light under nitrogen-deficientconditions [nitrogen-deficient cells, cf. Ohki and Fujita (1979)Plant & Cell Physiol. 20: 1341]. Both cells were found toform phycoerythrin (PE) in the dark after a short green illumination,while red illumination suppressed its formation. The amount of PE formation depended on the dose of green orred preillumination. Despite a large difference in content ofPRP of Scheibe, the dose-response of PE formation induced bygreen light was almost the same in both types of cells. Suppressionby red light in normal cells required a dose larger than thatin nitrogen-deficient cells. The results indicate that PRP ofScheibe formed during the incubation under nitrogen-deficientconditions does not act as the photoreceptor in photocontrolof PE formation. (Received September 29, 1980; Accepted January 6, 1981)     

Action spectra for chromatic adaptation in the blue-green alga Fremyella diplosiphon

Action spectra for chromatic adaptation in Fremyella diplosiphon Drouet have been determined using techniques previously described. Action maxima are at 540 nm, with a half-band width of 80 nm, for induction of phycoerythrin synthesis (green action) and at 650 nm, with a half-band width of 90 nm, for reversal of induction of phycoerythrin synthesis (red action). The red-action spectrum includes a secondary action band centered at ca. 360 nm. Red and green action overlap from 570 to 590 nm with an isosbestic point in the vicinity of 580 nm. Shoulders are present at 520 and 630 nm. Red light is more active than green light. The 540:650-nm quantum effectiveness ratio is 1:7. There is relatively little action of either kind in the blue. The 387:540 nm and 460:650-nm quantum effectiveness ratios are zero. These results contrast strongly with previous determinations in the same organism, with major activity indicated in the blue; they are consistent with the control of photomorphogenesis in the Cyanophyta by a master pigment, analogous to phytochrome.Abbreviations APC allophycocyanin - PC physocyanin - PE phycoerythrin     

Blue Light Induction of Carbonic Anhydrase Activity in Chlamydomonas reinhardtii

Blue light was specifically required for the induction of carbonicanhydrase (CA) activity in Chlamydomonas reinhardtii. The enhancingeffect of blue light (460 nm) was saturated at energy fluencerate as low as 0.6-0.8 W/m². The wavelength dependency curvehad a peak at 460 nm with no effect at wavelengths above 510nm, thus showing the strong similarities to other blue lightresponses in microalgae. CA induction was strongly inhibitedby UV irradiation at 280 nm. Experiments with the flavin quencher,potassium iodide, suggested that flavin is somehow involvedin CA induction. ¹On leave from the Institute of Biological Sciences, Collegeof Arts and Sciences, University of the Philippines at Los Banos,4031 College, Laguna, Philippines. (Received August 29, 1988; Accepted November 26, 1988)     

Blue and near ultraviolet reversible photoreaction with intracellular particulate fraction of the fungus, Alternaria tomato

In studies of the fungus, Alternaria tomato, we found the blueand near ultraviolet reversible photoreaction, which plays animportant role in photocontrol of conidial development, in thelight-minus-dark difference spectrum of the intracellular particulatefraction isolated from dark-grown mycelia. That is, after irradiationwith near ultraviolet, the difference spectrum of the particulatefraction showed a dip at 300 nm and a peak at 400 nm. When irradiatedwith blue light after exposure to near ultraviolet, both thepeak at 400 nm and the dip at 300 nm partially disappeared.This change was reversibly repeated by alternating doses ofblue and near ultraviolet. Action spectra for the light-mediatedchanges in the difference spectrum showed the peaks at 300 nmand 410 nm. (Received March 19, 1973; )     

Complementary Chromatic Adaptation in the Cyanobacterium, Tolypothrix tenuis: Location of Phycoerythrin Newly Synthesized by Green Illumination

Phycoerythrin (PE) formation in the dark induced by green preilluminationwas studied with the cyanobacterium Tolypothrix tenuis (IAMM29) with special attention to the localization of newly synthesizedPE. The initial synthesis of PE in the dark after preilluminationwas much faster than the formation of thylakoids indicated byChi increase. However, the amount of PE synthesized in thedark was far less than that needed for a complete change ofall phycobilisomes (PBS's) to the PBS containing PE at the maximumamount. These features give rise to questions as to whetherthe PE synthesized in the dark is located uniformly in everyPBS of every cell, or het-erogeneously in limited number ofcells, or PBS's newly divided or formed during the initial periodof the dark incubation. To solve the question, PE formationin individual cells was followed by a microscopic fluorometry,and at the same time, PE content in fractionated PBS was determined.Results indicated that (1) PE synthesis was induced uniformlyin every cell even by a limited dose of green light, and (2)PE was found in almost all PBS's. These results are interpretedas that newly synthesized PE is assembled in existing PBS, andthus, formation of PE-PBS induced by green light does not necessarilyrequire a new assembly of PBS. However exchange between PE andphycocyanin in peripheral rods of existing PBS probably occursat least in the initial phase of PE synthesis induced by greenlight. (Received August 16, 1990; Accepted February 27, 1991)     

Energy transfer processes in Gloeobacter violaceus PCC 7421 that possesses phycobilisomes with a unique morphology

We examined energy transfer dynamics in phycobilisomes (PBSs) of cyanobacteria in relation to the morphology and pigment compositions of PBSs. We used Gloeobacter violaceus PCC 7421 and measured time-resolved fluorescence spectra in three types of samples, i.e., intact cells, PBSs, and rod assemblies separated from cores. Fremyella diplosiphon, a cyanobacterial species well known for its complementary chromatic adaptation, was used for comparison after growing under red or green light. Spectral data were analyzed by the fluorescence decay-associated spectra with components common in lifetimes with a time resolution of 3 ps/channel and a spectral resolution of 2 nm/channel. This ensured a higher resolution of the energy transfer kinetics than those obtained by global analysis with fewer sampling intervals. We resolved four spectral components in phycoerythrin (PE), three in phycocyanin (PC), two in allophycocyanin, and two in photosystem II. The bundle-like PBSs of G. violaceus showed multiple energy transfer pathways; fast (≈ 10 ps) and slow (≈ 100 ps and ≈ 500 ps) pathways were found in rods consisting of PE and PC. Energy transfer time from PE to PC was two times slower in G. violaceus than in F. diplosiphon grown under green light.     

Effect of blue light on the photonastic reaction of rice leaves

Effect of blue light on the epinastic reaction of rice plantleaves (Oryza saliva L.) was studied. The inclination angleof intact leaves, when the plants were grown either in the lightor in the dark, was greatly increased by blue light irradiationbut not much increased by green, yellow, orange, red or whitelight. The effect of blue light on the epinastic reaction was,however, obscure in excised leaves, especially when they wereplaced on the horizontal. The photonastic reaction requireda prolonged irradiation of high intensity. The photosensitivesite localized at the leaf-nodal part. Response spectra forthe photonastic reaction were characterized by 2 distinct peaksat 420–440 mµ and 460–480 mµ and a fairlystrong response in the near ultra-violet region. (Received April 17, 1969; )     

In vivo transformation of phycobiliproteins during photobleaching of Tolypothrix tenuis to forms active in photoreversible absorption changes

The in vivo presence of the photoreversible pigment found byScheibe was examined with Tolypothrix tenuis before and afterphotobleaching. Crude protein extracts obtained from the cellsbefore photobleaching showed no photoreversible absorption changes.However, distinct photoreversible absorption changes were observedin crude protein extracts obtained from the cells after photobleaching.Results indicate that photobleaching caused the formation ofphotoreversible pigment(s) in vivo. Fractionation by brushitecolumn chromatography revealed that two photoreversible chromoproteinswere present in the latter extracts. One was eluted at the samefraction as allophycocyanin and showed a green minus red differencespectrum identical with that of Scheibe's photoreversible pigment(5), that of phycochrome c of Bj?rn and Bj?rn (2), and thatof our guanidine-HCl-treated allophycocyanin (7). The otherchromoprotein was found in the phycocyanin fraction and showeda green minus red difference spectrum resembling that of ourguanidine-HCl-treated phycocyanin (7) and that of the phycochromea of Bj?rn and Bj?rn (2). Results indicate that the photoreversiblechromoproteins present in cells after photobleaching were transformedin vivo from phycobiliproteins during the treatment. Re-evaluationof the photobiological role of these chromoproteins is necessary. (Received June 5, 1979; )     

Action Spectra for Phycobiliprotein Synthesis in a Chromatically Adapting Cyanophyte, Fremyella diplosiphon

The action spectra for phycocyanin production by the cyanophyte Fremyella diplosiphon shows maxima at 463 and 641 nm. The action spectrum for phycoerythrin production includes maxima at 387 and 550 nm. The maxima are based on a relative response rate well within the linear ascending portion of the dose response curves; the positions of the maxima are independent of the relative response rates chosen for reference over a 3-fold range although the comparative effectiveness of light at pairs of wavelengths varies with the standard used for comparison. These action spectra differ from those reported previously for Tolypothrix tenuis by Fujita and Hattori (Plant Cell Physiol. 3: 209-220) and by Diakoff and Scheibe (Plant Physiol. 51: 382-385) in that blue light strongly promotes phycobiliprotein synthesis in F. diphosiphon but has been reported to have little or no effect on T. tenuis.     

Phytochrome-mediated effects of near-ultraviolet radiation in the induction of flowering in etiolated Lemna paucicostata T-101, a short-day plant

Induction of flowering of etiolated Lemna paucicostata Hegelm. T-101, a short-day plant, was inhibited by far-red (FR) or blue light (BL) applied at the beginning of a 72-h inductive dark period which was followed by two short days. In either case the inhibition was reversed by a subsequent exposure of the plants to near-ultraviolet radiation (NUV), with a peak of effectiveness near 380 nm. Inhibition by BL or FR and its reversion by NUV are repeatable, i.e., NUV is acting in these photoresponses like red light although with much lower effectiveness. Thus, it is considered that NUV acts through phytochrome and no specific BL and NUV photoreceptor is involved in photocontrol of floral induction on this plant.Abbreviations BL blue light - FR far-red light - NUV near ultraviolet radiation - P red-absorbing form of phytochrome - P_fr far-red absorbing form of phytochrome - R red light     

Photo-Inhibition of Red-Light-Induced Spore Germination in Pteris vittata: Cyanide, Azide and Ethanol Counteracts Restorable Inhibitory Action of Near UV and Blue-light but not That of Far UV

In Pteris vittata, red-light-induction of spore germinationwas completely inhibited by subsequent irradiation with farUV (260 nm), near UV (380 nm) or blue (440 nm) monochromaticlight produced at the Okazaki Large Spectrograph. Germinationbut recovered from these photo-inhibition after less than 48h of darkness. Near UV- and blue-light-induced inhibition werestrongly counteracted by addition of 1 mM KCN, 1 RIM NaN₃ or100 mM ethanol. Far UV- and far red light-induced inhibition,however, was not influenced by these chemicals. Consequentlythe heights of peaks of action spectrum for this photo-inhibitionof spore germination was changed by addition of these chemicalsin the blue and near UV region but not at 260 nm. The resultssuggest that either or both of the photoreceptor system andthe signal transduction chain of the photo-inhibition are qualitativelydifferent between the shorter (i.e. far UV) and the longer (i.e.near UV and blue) wavelength regions. (Received August 31, 1989; Accepted February 19, 1990)     

Action Spectrum in the Ultraviolet Region for Phototropism of Bryopsis Rhizoids

The phototropic response of the rhizoid of the marine coenocyticgreen alga Bryopsis plumosa to ultraviolet light (250–350nm) was investigated. The rhizoid exhibited negative bendingthat was due to bulging upon absorption of light in the UV region,as well as in the visible region, of the spectrum. The negativebending might not be a result of the inhibition of growth onthe irradiated side of the apical hemisphere by UV irradiationbecause growth inhibition was observed after bending had reacheda maximum within one to two hours. The action spectrum obtainedfrom fluence rate-response curves had a pronounced peak at 260nm and a small peak at 310 nm. The quantum effectiveness at260 nm was about five times that in the visible region. Phenylaceticacid (PAA), a potent inhibitor of flavin photoreactions, inhibitedthe phototropic response to both UV light and blue light withoutany obvious effect on tip growth. The inhibition of the phototropicresponse to blue light by PAA was partially overcome by rinsingthe alga with riboflavin-containing medium, which result suggeststhe involvement of flavins in the phototropism of Bryopsis rhizoids. (Received February 6, 1995; Accepted June 19, 1995)     

Effects of Light Quality on Formation of 5-Aminolevulinic Acid, Phycoerythrin and Chlorophyll in Cryptomonas sp. Cells Collected from the Subsurface Chlorophyll Layer

Phycoerythrin obtained from the cells of Cryptomonas sp. (Cryptophyceae)which had been isolated from the subsurface chlorophyll layerin the western Pacific Ocean showed peaks in absorption andfluorescence spectra at 545 and 586 nm, respectively. The rateof photosynthetic O₂ evolution under green light was higherthan those under blue and red light. The rate of 5-aminolevulinic acid (ALA) accumulation in thepresence of levulinic acid was higher under green light thanunder blue and red light. The effects of light quality on therates of O₂ evolution and ALA formation closely resembled eachother. On the other hand, the formation of phycoerythrin andALA was suppressed during growth under blue light. Possible effects of light quality on the formation of photosyntheticpigments in Cryptomonas sp. were discussed. (Received January 31, 1984; Accepted May 14, 1984)     

Effects of blue light on respiration and carbon dioxide fixation in colorless Chlorella mutant cells

A colorless mutant of Chlorella vulgaris (Mutant #125) starvedin darkness, showed suppressed rates of respiration and darkCO₂ fixation, which were significantly recovered by illuminationwith blue light. The main CO₂ fixation product under blue lightwas aspartate. Such enhancements did not take place in cellsactively growing in the glucose medium. Both enhancing effectsof blue light (456 nm) were saturated at light intensities aslow as 400–800 erg.cm^-2.sec^-1. The action spectra forthese enhancing effects were similar to each other; both showedpeaks at 460 nm and 380 nm, which correspond to the absorptionmaxima of flavin. All these findings indicate that the samemechanism underlies the observed effects of blue light on CO₂fixation and respiration. The role of blue light which bringsabout the enhancements in CO₂ fixation and respiration is discussed. (Received June 1, 1974; )     

Fire Effects on Bud Viability and Growth of Stipa tenuis in Semiarid Argentina

Numbers of total, metabolically active, dormant or dead axillarybuds, and growth characteristics were determined before andafter controlled burnings in Stipa tenuis Phil., a native foragegrass of the Caldén District in central Argentina. One-hectareplots were burned on 25 Mar. (Burn 1) or 4 Apr. 1991 (Burn 2),or remained unburned (control). Bud metabolic activity was examinedusing the tetrazolium test and the vital stain Evans' blue. Before fire, more than 83% of the axillary buds on previous-seasonstems of S. tenuis were metabolically active in all treatments.After fire, previous-season stems that produced tiller in thecontrol and Burn 2 plots had more than 75% of the axillary budsalive, but those that did not produce them had more than 82%of their axillary buds dead in the burned areas. This high budmortality was associated with direct fire effects on the fateof buds; most dead buds showed visible signs of dehydration.Since more than 97% of the plant stem bases did not producetillers after fire, tiller number per plant was reduced (P <0·05) in the burned plots to fewer than 22% of valuesof controls. Plant mortality was 50% higher at the Burn 1 thanat the Burn 2 site probably because the first site had a 43%lower soil moisture content (P < 0·05). At the endof the growing season, however, a different set of S. tenuisplants at both burned sites had a similar tiller number anddry weight to controls. These plants were probably in areasof lighter fuel loads and exposed to a less intense fire.Copyright1993, 1999 Academic Press Stipa tenuis Phil., thin needlegrass, controlled burning, bud viability, axillary meristems, regrowth     

Convergence and divergence of the photoregulation of pigmentation and cellular morphology in Fremyella diplosiphon

Photosynthetic pigment accumulation and cellular and filament morphology are regulated reversibly by green light (GL) and red light (RL) in the cyanobacterium Fremyella diplosiphon during complementary chromatic adaptation (CCA). The photoreceptor RcaE (regulator of chromatic adaptation), which appears to function as a light-responsive sensor kinase, controls both of these responses. Recent findings indicate that downstream of RcaE, the signaling pathways leading to light-dependent changes in morphology or pigment synthesis and/or accumulation branch, and utilize distinct molecular components. We recently reported that the regulation of the accumulation of the GL-absorbing photosynthetic accessory protein phycoerythrin (PE) and photoregulation of cellular morphology are largely independent, as many mutants with severe PE accumulation defects do not have major disruptions in the regulation of cellular morphology. Furthermore, morphology can be disrupted under GL without impacting GL-dependent PE accumulation. Most recently, however, we determined that the disruption of the cpeR gene, which encodes a protein that is known to function as an activator of PE synthesis under GL, results in disruption of cellular morphology under GL and RL. Thus, apart from RcaE, CpeR is only the second known regulator to impact morphology under both light conditions in F. diplosiphon.     

Effects of disalicylidenepropandiamine and near far-red light on 14CO2-fixation in Chlorella cells

1) With Chlorella ellipsoidea cells, in the presence of 5x10^–6M DSPD, or in its absence, the amounts of ¹⁴CO₂ incorporatedin P-esters, serine-plus-glycine and alanine were larger underred light than under blue light, whereas blue light specificallyincreased ¹⁴CO₂-incorporation in aspartate, glutamate, malateand fumarate (blue light effect). The amount of total ¹⁴C fixedunder blue or red light was greatly decreased by the additionof DSPD. When the concentration of DSPD was raised to 5x10^–4M, practically no radioactivity was found, under blue or redlight, in aspartate, glutamate and fumarate. Radioactivity inalanine was greatly increased. Effects of higher concentrationof DSPD are explained as due to the inhibition of PEP carboxylaseactivity in Chlorella cells. 2) The percentage incorporation of ¹⁴C into aspartate and theother compounds mentioned above, under near infra-red illuminationwas significantly smaller than that under blue light and wasalmost equal to that under red light. These results along withthe effect of 5x10^–6 M DSPD, exclude the possibility thatcyclic photophosphorylation is involved in the "blue light effect"mechanism. (Received December 12, 1969; )