Search results for "synthesis"
showing 10 items of 2844 documents
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.
Measurements of cytochrome f and P-700 in intact leaves of Sinapis alba grown under high-light and low-light conditions
1978
The oxidation and reduction of cytochrome f and P-700 is measured spectrophotometrically in leaves of low-light and high-light plants. After illumination with red light, an induction phenomenon for cytochrome f oxidation is observed which indicates a regulation of photosystem I activity through energy distribution between the pigment systems by the energy state of the membrane. After far-red excitation the reduction of cytochrome f in the dark is much slower in low-light leaves. This shows that cyclic electron transport is not improved in low-light plants under these conditions. P-700 is oxidized on excitation with far-red light. However, with high intensities of far-red light, P-700 is par…
Studies on the Content of P 700 and Cytochromes in Sinapis alba During Growth Under Two Different Light Intensities
1975
Sinapis alba was grown under two extremely different light intensities. We obtained two different modifications which hold several physiological and biochemical characteristics comparable to the relations in light- and shade plants. In the strong light the maximum rate of CO2-uptake increases within five days to a three-fold rate. At the same time the content of several redox systems of photosynthetic electron transport increases while the content of P 700 remains equivalent in both types of plants. In the high-light plants we find a ratio P 700: Cytochrome f of 1 but a ratio of 3 in the low-light plants. These ratios could be probably essential features of various sun- and rainforest speci…
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).
Cytochrome c is released in a single step during apoptosis
2005
Release of cytochrome c from mitochondria is a central event in apoptotic signaling. In this study, we utilized a cytochrome c fusion that binds fluorescent biarsenical ligands (cytochrome c-4CYS (cyt. c-4CYS)) as well as cytochrome c-green fluorescent protein (cyt. c-GFP) to measure its release from mitochondria in different cell types during apoptosis. In single cells, the kinetics of cyt. c-4CYS release was indistinguishable from that of cyt. c-GFP in apoptotic cells expressing both molecules. Lowering the temperature by 7 degrees C did not affect this corelease, but further separated cytochrome c release from the subsequent decrease in mitochondrial membrane potential (DeltaPsi(m)). Cyt…
Subcellular localization of pentachlorophenol 4-monooxygenase in Sphingobium chlorophenolicum ATCC 39723.
2002
Abstract We have studied the subcellular localization of pentachlorophenol 4-monooxygenase (PCP4MO) in Sphingobium chlorophenolicum ATCC 39723 during induction by pentachlorophenol (PCP). Using a monoclonal antibody CL6 specific to the native and recombinant PCP4MO, the enzyme was primarily found soluble as determined by immunoblot and ELISA analyses of cellular fractions. However, the enzyme was observed both in the soluble and membrane-bound forms during induction for 2–4 h, suggesting its translocation out from the cytoplasm. Electron microscopy confirmed that PCP4MO was predominantly present in the cytoplasm at 1 h, whereas at 4 h significant amount was detected also in the membrane and…
Deciliation: A stressful event for Paracentrotus lividus embryos.
1998
In this report, by using mono- and two-dimensional electrophoretic analysis, we demonstrate that deciliation on sea urchin embryos induces a stress response. Deciliation indeed causes not only the activation of ciliary subroutine, but also a transient decrease of bulk protein synthesis. This decrease is in agreement with our previous results on heat shock response in sea urchin, although deciliation does not induce the expression of the same main hsp set. We were able to characterize one main deciliation-stress protein of 40 kDa whose expression is transiently induced by deciliation and whose localisation is likely to be nuclear.
Regulation of ribonucleotide reductase in response to iron deficiency
2011
Ribonucleotide reductase (RNR) is an essential enzyme required for DNA synthesis and repair. Although iron is necessary for class Ia RNR activity, little is known about the mechanisms that control RNR in response to iron deficiency. In this work, we demonstrate that yeast cells control RNR function during iron deficiency by redistributing the Rnr2–Rnr4 small subunit from the nucleus to the cytoplasm. Our data support a Mec1/Rad53-independent mechanism in which the iron-regulated Cth1/Cth2 mRNA-binding proteins specifically interact with the WTM1 mRNA in response to iron scarcity, and promote its degradation. The resulting decrease in the nuclear-anchoring Wtm1 protein levels leads to the re…
Selective targeting of avidin/mannose 6-phosphate receptor chimeras to early or late endosomes
2000
Summary In this study we have used the Semliki forest virus expression system to transiently express chimeric proteins that contain transmembrane and cytoplasmic domains of the cation-independent mannose 6-phosphate receptor (CI-MPR) fused to chicken avidin. Immunofluorescence and electron microscopy studies showed that the chimeric protein with the entire cytoplasmic domain of CI-MPR was transported to late endosomes, where it accumulated. We made use of the biotin-binding capacity of lumenal avidin, and found that, in agreement with this distribution, the chimeric protein could be labelled with biotinylated HRP endocytosed for a long, but not a brief, period of time. However, truncation o…