ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb07573.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractNon‐stationary photoconversions of the two forms of the photochromic sensory plant pigment phytochrome are theoretically analyzed. It is shown that from actualin situmeasurements of changes of absorbances caused by these photoconversions in a sequence of exposures to actinic light, one can calculate the spatial distribution of phytochrome along the path of the actinic beam.The necessary condition of such a calculation is the existence of a screen with a known spatial distribution, which must be obtained in an independent experiment. Thus, the possibility is proved to measure, instead of phytochrome spatial distribution, that of the screen which is a much larger chemical and optical body inside the object.Expressions to calculate the spatial distribution of phytochrome and to estimate the errors involved are presented in the present pape

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb07574.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractAn approach to determine the photomorphogenic effect of light (white or continuous far‐red) on the development of rhythmic enzyme activity inChenopodium rubrumL. is described. Previous results, obtained from mature seedlings grown in white light, demonstrated stable oscillations with periods ranging between 12 and 15 h for all of the enzymes tested. The present results, obtained during deetiolation, were complicated by the presence of a higher frequency component with a period of about 6 h. When the various oscillating components were defined, the analysis showed: (1) the enzymes of the Krebs cycle (malate and isocitrate dehydrogenase), the closely associated glutamate dehydrogen‐ase, and the glycolytic pathway ((NAD) glyceraldehyde‐3‐phosphate dehydrogenase) had a dominant period in the range of 12–15 h, (2) those of the oxidative pentose phosphate pathway were either weakly circadian (glucose‐6‐phosphate dehydrogenase) or apparently arhythmic (6‐phosphogluconate dehydrogenase), (3) the (NADP) glyceraldehyde‐3‐phosphate dehydrogenase from the Calvin cycle was circadian when kept in continuous darkness but becomes 15 h when placed in light, and (4) only the Calvin cycle enzyme is affected by light in the level of its activity and in its o

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb07575.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractPhytochrome conversion shifts the developmental pattern of dark‐grown bean (Phaseolus vulgaris) seedlings. Red light was found to initiate rapid oscillations in a system that links illumination with subsequent growth. A single 8 s flash of red light increased the average leaf weight measured 24 h later by 8%. When total illumination was kept constant but the interval between two 4 s flashes was varied, the resulting leaf weight increase was not uniform but depended on the length of the interval between flashes and showed a series of deep minima followed by sharp maxima. Weight increase at the maximum was 60% greater than at the minimum. The minimum‐maximum transitions recurred every 45 s for at least 22 min. Four s of far red light interposed between the two red flashes abolished the oscillation. Temperature between 15 and 30°C had no significant influence on the period of the oscillation but the period varied directly with the duration of the initial red flash. A 2 s initial flash resulted in a 35 s period, while 40 s of red light caused a 2 min period. Oat (Avena sativa) and radish (Raphanus sativus) seedlings were found to possess similar oscillating mechanisms of growth regulation. The lack of pronounced temperature effects as well as our other findings, suggest that this oscillating system may participate in the time measuring as well as growth regulating mechanisms by which phytochrome controls circadian periodicity and develop

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb07576.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe flat, ribbon‐shaped chloroplast in the filamentous green algaMougeotiasp. undergoes light‐induced orientational movement controlled by an intracellular tetrapolar gradient of the active form of phytochrome, Pfr. Some substructural and physiological aspects of this reaction were studied. An intracellular pattern of microfilaments (diameter: 5–10nm), presumably related to chloroplast movement, was identifiedin situ. In addition, it could be shown that chloroplast movement decreases parallel to a nitric acid soluble fraction of intracellular calcium. These results might indicate that phytochrome governs chloroplast movement inMougeotiavia control of the binding state of ca

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb07577.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe unfolding of etiolated barley leaves was induced by two short pulses of light separated by a dark interval. For certain wavelengths of light the effect of the “second light pulse was enhanced when the pulse was given after a 300–2000 s dark interval as compared with its effect when the two light pulses were given simultaneously. We investigated the spectral dependence of the effect of the first, inducing light flash and of the effect of the second Light flash given after a 500 s dark interval. The spectral actinity for the effect of the first flash showed phytochrome involvement. The spectral actinity for the effect of the second light flash, however, was shifted towards shorter wavelengths and the inductive action of red and far red light was attenua

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb07578.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe enhanced phytochrome pelletability that results fromin vivoirradiation ofAvenashoots may be divided into two operationally defined sequential stages: thein vivodevelopment of a “potential to pellet” and the “expression” of this potentialin vitro. Kinetic studies confirm previous findings that the generation of this “potential to pellet” is a very rapid (complete in<10 s, 25°C), genuinely intracellular process, itself photoreversibly induced by Pfr. In addition, it is shown that the sustained development of the “potential to pellet”, that proceeds in the dark at 0°C following a red pulse, requires Pfrcontinually in the cell over the entire development period. Far red light immediately terminates further development of the red‐induced “potential” at any point during the development phase. No immediate reduction is observed, however, in that level of “potential pelletability” already attained at the time of the far red pulse. This indicates that the level of “potential pelletability” establishedin vivois insensitive to the form of the pigment at extraction regardless of the level reached. “Expression” of the “potential to pellet” refers to the actual detection in homogenates of an enhanced physical association of phytochrome with pelletable material. Maximum “expression” requires the presence of a divalent cation in the medium during homogenization. Rapid posthomogenization addition of Mg2+to Mg2+‐free extracts sustains enhanced pelletability but with rapidly declining effectiveness over the fmt 1–2 min after extraction. The rate of decline is faster if the phytochrome is present as Pfrthan as Prin the homogenate. Neither these nor previous data permit a distinction to be made between (a) preservation by the cation of a pre‐existing intracellular interaction, and (b) a Mg2+‐mediated induction of an artifactual,in vitroassociation predetermined in the cell by a genuine phyto‐chrome‐controlled process. Various formalistic mode

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb07579.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractExcised roots of pea seedlings (Pisum sativumvar. “Alaska”) cultured in a synthetic medium under sterile conditions exhibit differentiation of functional chloroplasts from leucoplasts when irradiated with blue light (350–550 nm). This transition is a relatively slow process; nevertheless, the chloroplasts formed in blue light compare very well to leaf chloroplasts as far as microstructure and photosyn‐thetic activities are concerned.Apparently certain activities of the apical meristem are mandatory in bringing about a transition from leucoplasts to chloroplasts in blue light. After short‐time labelling with [jH]uridine the synthesis of plastid ribosomal RNA (rRNA) was studied either during irradiation with blue and red light (600–700 nm), respectively, or in darkness. Polyacrylamide gel electrophoresis revealed that in blue light the synthesis of specific chloroplast rRNA species with molecular weights of 1.1 × 106and 0.56 × 106daltons is markedly stimulated. In contrast, in dark cultured roots these RNA species were synthesized to a limited extent only whereas the cytoplasmic rRNA species of 1.3 × 106and 0.7 × 106daltons molecular weight were preferentially formed. The same holds true for roots irradiated

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb07580.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe kinetics of35S methionine incorporation into soluble and membrane proteins during the transition from steady state dark growth to greening was studied inSpirodela. A sharp increase in the rate of incorporation occurred at 3 h, which was several h before major increases in chlorophyll were apparent. Part of this enhanced incorporation was due to enhanced synthesis of a32,000 dalton membrane protein. This synthesis was paralleled by a temporal increase inin uitrotemplate capacity for this protein and an increase in 0.5 × 106dalton plastid messenger RNA

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb07581.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractA plastid mRNA (5 × 105mol wt) appears as a burst 3 h after white light greening of steady state dark grown plants ofSpirodela oligorrhiza. In this species, chlorophyll synthesis begins after 12 h. The light requirement is different from the pulse of far‐red reversible red light required to abolish the lag of chlorophyll synthesis in many species, includingSpirodela. Continuous high energy far‐red is not stimulatory. When the illumination is not continued throughout the time of incorporation, the stimulation is minimal. Low energy blue and red light are stimulatory, and green and far‐red light are ineffectual. Blue light was>5 times as effective as red light at many dose levels. Illumination with 3 × 1017quanta/m2/s (50pEm/cm2/s) blue light at 476 nm gave about half maximum stim

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb07582.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY