Search results for "Chlorophyll"
showing 10 items of 453 documents
The Variability of the Photosynthetic Unit in Chlorella Fusca
1984
The concept of the photosynthetic unit (PSIT) was introduced by Gaffron and Wohl (1936) on the basis of Emerson and Arnold’s flash light experiments (1932). The PSU was defined as the minimum of chlorophyll molecules required for the evolution of one O2. Later on, the PSU was considered to be the complex of one reaction center and its appropriate antenna of light harvesting chlorophyll molecules. Assuming that there is an equal number of the PS I and PS II reaction centers the PSU was mostly expressed as Chl/P-700. However, recently it could be shown that the ratio of PS II/PS I is variable depending on the light conditions during growth (Kawamura et al., 1979; Myers, Graham, 1982). Further…
The concentration of Cytochrome f and P700 in chlorophyll-deficient mutants of Chlorella fusca
1977
The ratio of Chlorophyll: Cytochrome f and of Chlorophyll: P700 (reaction center pigment in photosystem I) is essentially lower in chlorophyll-deficient mutants than in the normal green strain. On a dry weight basis, the mutants have the same or a higher content of redox enzymes than the normal form. The size of the photosynthetic unit of the mutants is 4 to 7 times smaller than that of the normal strains, due mainly to a deficiency of the light-harvesting chlorophyll-protein complex.
Comparative Investigations on the Photosynthetic Electron Transport Chain of Spruce (Picea Abies) with Different Degrees of Damage in the Open Air
1988
Several components of the photosynthetic electron transport chain (P-700, cytochrome f, QB-protein) as well as the rate of electron transport and the chlorophyll content of the needles of spruce trees with different degrees of damage were investigated. The investigations were carried out in pair comparison at a location in the Hunsruck (West Germany). The rate of electron transport was determined as photoreduction of 2,6-dichlorophenolindophenol. Significant damage to the electron transport system is shown in the thylakoids of the damaged trees compared to the less severely damaged trees. In the spruce trees with more damage, the rates of electron transport are significantly lower. The inve…
Changes in the Content of Chlorophyll and Redox Components of the Thylakoid Membrane during Development and Senescence of Beech (Fagus sylvatica) Lea…
1995
Abstract Leaves from 145-year-old and 44-year-old beech trees were harvested during 1991-1993. Chlorophyll (Chl) and redox components of the thylakoid membrane, including P-700, cytochrome f (Cyt f) and D1 protein, were determined with the following results. Chl a + b, P-700 and Cyt f per unit of fresh weight (FW), dry weight (DW) and leaf area (LA) increase significantly during leaf development. This can be attributed to a massive membrane synthesis and new thylakoid formation in the cells. The Chl a/Chl b ratio decreases with the synthesis of Chl during the development of beech leaves and is reduced further with Chl breakdown in the stage of senescence. When expressed on the basis of Chl…
The Effect of Blue and Red Light on the Content of Chlorophyll, Cytochrome f, Soluble Reducing Sugars, Soluble Proteins and the Nitrate Reductase Act…
1980
The photosynthetic characteristics of many species of plants are influenced by the light intensity under which the plant is grown. This is shown by the light saturation curves for CO2 uptake. Both the light intensity required for saturation and the light-saturated rate of CO2 uptake increase with the light intensity under which the plant is grown. Photosynthetic adaptation to different light levels involves balanced changes of many leaf factors. Low-light and high-light plants differ in a number of component steps of photosynthesis as well as in the structure and composition of the photosynthetic apparatus and in the leaf anatomy (see reviews by Boardman 1977; Wild 1979).
Measurements of manganese in thylakoids of Sinapis alba grown under high-light and low-light conditions.
1981
The manganese content of thylakoids and tissues was measured in leaves grown under high- and low-light conditions. Especially when grown in a nutrient medium enriched in manganese (20 μM), the thylakoids contained large amounts of manganese, which could be removed by EDTA washing without impairment of the Hill reaction. The unremovable content of manganese was almost the same in thylakoids from plants grown in nutrient media of normal (2 μM) and reduced (0.2 μM) manganese content. Up to this limit of manganese content, Hill activity did not seem to be impaired. 1.2 atoms Mn per 100 molecules chlorophyll were found in low-light thylakoids and 1.6 atoms Mn in high-light thylakoids. This is si…
Cyclic and noncyclic photophosphorylation during the ontogenesis of high-light and low-light leaves of Sinapis alba.
1981
Noncyclic electron transport to ferricyanide and photophosphorylation as well as the methylviologen mediated aerobic and anaerobic photophosphorylation with dichlorophenolindophenol-ascorbate as the electron donor of photosystem I were measured during the development of high-light and low-light adapted leaves of Sinapis alba. Anaerobic methylviologen-catalyzed phosphorylation is more than twice as high as aerobic phosphorylation. The difference between the rates of aerobic and anaerobic phosphorylation is sensitive to dibromothymoquinone. Thus, under anaerobic conditions, methylviologen mediates a cyclic phosphorylation including plastoquinone. All photochemical activities of high-light chl…
PREDICTION OF HARVEST TIME IN PEACH [PRUNUS PERSICA (L.) BATSCH] FRUIT USING THE DA-METER
2015
The aim of this work was to define the most appropriate time of harvesting early ripening peach fruit using destructive and non-destructive quality indexes such as the index of absorbance (IAD), measured with the DA-Meter, a portable equipment able to measure the degradation of chlorophyll in the pericarp. In this context our research was carried out in 2009 and 2010 on several peach cultivars. Total soluble solid content increased while flesh firmness and total acidity decreased with IAD values, but no significant correlation was found between destructive and non-destructive parameters.
KOSMOS 2018 Gran Canaria mesocosm study: water column biogeochemistry
2021
The data set compiles biogeochemical water column collected during a KOSMOS mesocosm experiment carried out in the frame work of the Ocean Artificial Upwelling project. The experiment was performed in the North-East Atlantic Ocean off the coast of Gran Canaria in autumn 2018 and lasted for 39 days. In this study we investigated the effect of different intensities of artificial upwelling combined with two upwelling modes (recurring additions versus one singular addition) on POC export and its potential transfer efficiency to depth. The data set includes the amounts of surface water that were exchanged with nutrient-rich deep water (from ~300 m depth), primary production and chlorophyll a, el…
Thalassobacter stenotrophicus Macián et al. 2005 is a later synonym of Jannaschia cystaugens Adachi et al. 2004, with emended description of the genu…
2005
The type strains of Jannaschia cystaugens (LMG 22015T) and Thalassobacter stenotrophicus (CECT 5294T) were analysed by means of genomic DNA–DNA hybridization, comparison of 16S rRNA gene sequences and phenotypic properties determined under the same methodological conditions. J. cystaugens LMG 22015T showed DNA–DNA relatedness levels of 72 % when hybridized with the genomic DNA of T. stenotrophicus CECT 5294T. Sequence comparisons revealed that the 16S rRNA genes of the two strains had a similarity of 99·8 %. The cellular fatty acid and polar lipid compositions of the two strains and their DNA mol% G+C contents were almost identical. Bacteriochlorophyll a (Bchl a) and polyhydroxybutyrate wer…