scholarly journals THE FINE STRUCTURE OF RHODOSPIRILLUM RUBRUM

1963 ◽  
Vol 16 (2) ◽  
pp. 401-419 ◽  
Author(s):  
Germaine Cohen-Bazire ◽  
Riyo Kunisawa
Keyword(s):  
Fine Structure ◽  
Light Intensity ◽  
Chlorophyll Content ◽  
Rhodospirillum Rubrum ◽  
Photosynthetic Pigment ◽  
Photosynthetic Apparatus ◽  
High Light Intensity ◽  
Thin Sections ◽  
Lead Hydroxide ◽  
In Cells

The fine structure of Rhodospirillum rubrum grown under a series of defined conditions has been examined in thin sections prepared by the methods of Ryter and Kellenberger. In cells grown anaerobically at different light intensities, the abundance of 500 A membrane-bounded vesicles in the cytoplasm is inversely related to light intensity, and directly related to cellular chlorophyll content. When the chlorophyll content of the cell is low, the vesicles are exclusively peripheral in location; they extend more deeply into the cytoplasm when the chlorophyll content is high. Typical vesicles also occur, though rarely, in cells grown aerobically in the dark, which have a negligible chlorophyll content. When synthesis of the photosynthetic pigment system is induced in a population of aerobically grown cells by incubation under semianaerobic conditions in the dark, the vesicles become increasingly abundant with increasing cellular chlorophyll content, and the cells eventually acquire the cytoplasmic structure that is characteristic of cells growing anaerobically at a high light intensity. Poststaining with lead hydroxide reveals that the membranes surrounding the 500 A vesicles are indistinguishable in structure from the cytoplasmic membrane, and continuous with it in some areas of the sections. The bearing of these observations on current notions concerning the organization of the bacterial photosynthetic apparatus is discussed.

scholarly journals THE EFFECT OF LIGHT INTENSITY AND SUCROSE FEEDING ON THE FINE STRUCTURE IN CHLOROPLASTS AND ON THE CHLOROPHYLL CONTENT OF ETIOLATED LEAVES

1962 ◽  
Vol 14 (2) ◽  
pp. 169-182 ◽  
Author(s):  
Yael Eilam ◽  
S. Klein
Keyword(s):  
Fine Structure ◽  
Light Intensity ◽  
Chlorophyll Content ◽  
Sucrose Solution ◽  
Tap Water ◽  
High Light Intensity ◽  
Plastid Development ◽  
Low Light ◽  
Etiolated Leaves

Changes in the fine structure of proplastids of etiolated leaves exposed to various conditions of light and darkness for 24 and 48 hours were investigated, and the chlorophyll content of the leaves so treated was determined in vivo. The light treatments were given while the leaves were floated on tap water or on a 0.2 M sucrose solution. Leaves floated on water under low light intensity (2 foot-candles) were low in chlorophyll and contained plastids with concentric rows of vesicles. Transferring the leaves back to darkness resulted in the disappearance of the concentric rigs and re-formation of vesicular centers together with straight rows of vesicles and tubules, evenly spaced throughout the stroma. Chloroplasts of leaves floated on a sucrose solution under low light showed large vesicular centers together with stacks of rows of elongated tubules. The same chloroplast structure was found in leaves floated on a sucrose solution in the dark, after having been exposed to weak light for 24 hours. Chlorophyll content in these leaves was the same as in leaves floated on water under high light intensity, where the chloroplasts had normal grana and lamellae. The effect of the investigated factors on plastid development is discussed.

Differential Changes in the Photosynthetic Pigments and Polyamine Content during Photoadaptation and Photoinhibition in the Unicellular Green Alga Scenedesmus obliquus

1998 ◽  
Vol 53 (9-10) ◽  
pp. 833-840 ◽  
Author(s):  
Kiriakos Kotzabasis ◽  
Dieter Dörnem
Keyword(s):  
Light Intensity ◽  
Green Alga ◽  
Scenedesmus Obliquus ◽  
Photosynthetic Pigment ◽  
Photosynthetic Apparatus ◽  
High Light Intensity ◽  
High Light ◽  
Light Conditions ◽  
Unicellular Green Alga ◽  
Polyamine Level

In the unicellular green alga Scenedesmus obliquus the level of photoinhibition and the recovery of the cells after reversal to the initial light conditions in relation to the pre-photoadaptation of the culture to low, medium and high light intensity was determined. The changes in the photosynthetic pigment content and in the intracellular polyamine concentration allowed to distinguish between photoadaptation and photoinhibition. In particular, the level of chlorophylls, xanthophylls and carotenoids decreased inversely proportional to the light intensity applied during photoadaptation, whereas their concentrations remained constant during photoinhibition. The violaxanthin/zeaxanthin and the loroxanthin/lutein cycle work only under photoinhibitory conditions, but not under photoadaptive premises. Changes in the level of these carotenoids in relation to the changes in the photosynthetic apparatus during photoadaptation are discussed. In addition, it was found that the intracellular polyamine level increased only under stress conditions, i. e. during photoinhibition, and decreased during recovery of the cells after reversal to the initial light conditions. The increase of the putrescine level during photoinhibition is inversely proportional to the light intensity used for pre-adaptation. This rise of the polyamine level in the cells photoadapted to high light conditions is an additional indication for the finding that photoadaptation and photoinhibition are different phenomena which are clearly distinguishable from each other. Finally, the changes of the chlorophyll, violaxanthin, zeaxanthin, loroxanthin, lutein and polyamine levels under photoadaptation in high light intensity (50 W m -2) in relation to the range of photoadaptation in Scenedesmus obliquus are discussed.

High light intensity protects photosynthetic apparatus of pea plants against exposure to lead

2006 ◽  
Vol 44 (5-6) ◽  
pp. 387-394 ◽  
Author(s):  
E. Romanowska ◽  
B. Wróblewska ◽  
A. Droƶak ◽  
M. Siedlecka
Keyword(s):  
Light Intensity ◽  
Photosynthetic Apparatus ◽  
High Light Intensity ◽  
High Light

Influence of Fluridone on Chlorophyll Content of Wheat (Triticum aestivum) and Corn (Zea mays)

Weed Science ◽  
1978 ◽  
Vol 26 (5) ◽  
pp. 432-433 ◽  
Author(s):  
R. M. Devlin ◽  
C. N. Saras ◽  
M. J. Kisiel ◽  
A. S. Kostusiak
Keyword(s):  
Triticum Aestivum ◽  
Zea Mays ◽  
Light Intensity ◽  
Chlorophyll Content ◽  
High Light Intensity ◽  
Carotenoid Content ◽  
Low Light ◽  
Low Light Intensity ◽  
Chlorophyll Production ◽  
Effect Of Light

Chlorophyll content of wheat (Triticum aestivum L. ‘Mericopa’) and corn (Zea mays L. ‘Merit’) treated with the herbicide fluridone {1-methyl-3-phenyl-5-[3-(trifluoromethyl)-phenyl]-4(1H)-pyridinone} and grown under high light intensity (10.8 klux), was markedly reduced. Corn and wheat germinated from seeds treated with 10 uM fluridone and grown for 6 days were almost completely bleached. Under low light intensity (108 lux) the influence of fluridone on chlorophyll production was greatly reduced. Under very low light intensity (21.5 lux) this influence was almost completely lost. The effect of light on the activity of fluridone suggests that the inhibition of carotenoid production may represent the mode of action of this herbicide. This study shows that the carotenoid content of wheat or corn drops dramatically when these plants are treated with fluridone.

La photorespiration se déroulant dans un air sans CO2 a-t-elle une fonction?

1978 ◽  
Vol 56 (17) ◽  
pp. 2128-2137 ◽  
Author(s):  
Gabriel Cornic
Keyword(s):  
Light Intensity ◽  
Photosynthetic Apparatus ◽  
Qualitative Change ◽  
Sinapis Alba ◽  
Inhibitory Effect ◽  
High Light Intensity ◽  
Long Term Effects ◽  
Net Assimilation ◽  
The Warburg Effect

Long-term effects of a low O2 and CO2, atmosphere on photosynthesis were studied on Sinapis alba L. It was shown that this could induce strong and durable changes on the subsequent photosynthesis measured at different CO2 and O2 concentrations. Two mains effects were observed: (1) an inhibition of net assimilation measured at 21% or 0.1% O2; (2) a qualitative change of the Warburg effect. After the treatment, high CO2 concentrations did not reverse the inhibitory effect of O2 on photosynthesis.The effect of the low O2 and CO2 atmosphere, characterized by the inhibition of net assimilation, was analyzed by varying the following factors during plants treatment: light intensity, temperature, and CO2 and O2 concentrations. The inhibition was higher under high light intensity, increased with temperature, and was apparent within the following limits of CO2 and O2 concentration, respectively, 0 to 0.018% CO2 and 0.1 to 4% O2.The results are discussed to determine if they showed that an inhibition of photorespiration in a low CO2 atmosphere has a function in the photosynthetic apparatus.

scholarly journals THE FINE STRUCTURE OF GREEN BACTERIA

1964 ◽  
Vol 22 (1) ◽  
pp. 207-225 ◽  
Author(s):  
Germaine Cohen-Bazire ◽  
Norbert Pfennig ◽  
Riyo Kunisawa
Keyword(s):  
Fine Structure ◽  
Cytoplasmic Membrane ◽  
Photosynthetic Apparatus ◽  
Gram Negative Bacteria ◽  
Green Bacteria ◽  
Thin Sections ◽  
Cytological Features ◽  
Cortical Vesicles ◽  
Chlorobium Vesicles ◽  
Very High

The fine structure of several strains of green bacteria belonging to the genus Chlorobium has been studied in thin sections with the electron microscope. In addition to having general cytological features typical of Gram-negative bacteria, the cells of these organisms always contain membranous mesosomal elements, connected with the cytoplasmic membrane, and an elaborate system of isolated cortical vesicles, some 300 to 400 A wide and 1000 to 1500 A long. The latter structures, chlorobium vesicles, have been isolated in a partly purified state by differential centrifugation of cell-free extracts. They are associated with a centrifugal fraction that has a very high specific chlorophyll content. In all probability, therefore, the chlorobium vesicles are the site of the photosynthetic apparatus of green bacteria.

scholarly journals Badania możliwości stosowania norflurazonu do zwalczania Agropyron repens L. Część I. Wpływ norflurazonu na zawartość chlorofilu i karotenu w perzu rozgłogowym [Effect of Norflurazon in weed control. P. I. Influence of Narflurazon on pigment's content in Agropyrcn repens L.]

2015 ◽  
Vol 30 (1) ◽  
pp. 135-150
Author(s):  
Stanisław Karczmarczyk ◽  
Irena Zbieć
Keyword(s):  
Light Intensity ◽  
Chlorophyll Content ◽  
Weed Control ◽  
High Light Intensity ◽  
High Light ◽  
Low Light ◽  
Content Development ◽  
Higher Doses ◽  
Agropyron Repens

The influence of Narflurazon on chlorophyll content, development of <i>Agropron repens</i> L. plants grown under high and low light intensites was studied. Under high light intensity (10 000 lx) both chlorophyll and carotenoides production was markedly reduced, 0.5 ppm and more of Norflurazon bleac ed the platns almost competely. Higher doses of Norflurazon (0.025 ppm and more) significantly inhibited growth and respiration of <i>Agropyron repens</i>.

Sign in / Sign up

Export Citation Format

Share Document