The Relationship between the Energy Dependent Quenching of Chlorophyll Fluorescence and the Capacity of O2 Evolution at PS II in Vivo

1995 ◽  
pp. 3247-3250
Author(s):  
Bernard Genty ◽  
Fulvia Rizza ◽  
Denise Ruelle
Keyword(s):  
Chlorophyll Fluorescence ◽  
O2 Evolution ◽  
Ps Ii ◽  
Energy Dependent ◽  
The Relationship

Mechanism of Non-Photochemical Chlorophyll Fluorescence Quenching. II. Resolution of Rapidly Reversible Absorbance Changes at 530 Nm and Fluorescence Quenching by the Effects of Antimycin, Dibucaine and Cation Exchanger, A23187

1995 ◽  
Vol 22 (2) ◽  
pp. 239 ◽  
Author(s):  
N Mohanty ◽  
AM Gilmore ◽  
HY Yamamoto
Keyword(s):  
Chlorophyll Fluorescence ◽  
Fluorescence Quenching ◽  
Cation Exchanger ◽  
Thylakoid Membranes ◽  
Chlorophyll Fluorescence Quenching ◽  
Absorbance Changes ◽  
Energy Dependent ◽  
The Relationship ◽  
Effect Of Inhibitors ◽  
Exchange Properties

The putative relationship between the light-induced absorbance increase at 530 nm (ΔA530), the so-called light-scattering change, and non-photochemical chlorophyll fluorescence quenching (NPQ) was examined by the effect of inhibitors. Antimycin at a low concentration (350 nM) completely inhibited fluorescence quenching while only partially inhibiting A530. This effect was independent of the mode of thylakoid energisation and preinduction of violaxanthin de-epoxidation. Dibucaine at 20 FM abolished NPQ but had little effect on ΔA530. Moreover, the light-induced ΔA530 signal was present even in the absence of de-epoxidised xanthophylls. The cation exchanger A23187 blocked the development of NPQ as well as relaxed fluorescence quenching at steady state without involving a major portion of ΔA530. Thus, the relationship between energy-dependent A530 changes and fluorescence quenching was non-linear under all conditions tested. The light-induced absorbance increase at 530 nm, therefore, is insufficient for NPQ. The differential effects of inhibitors are explained schematically, depicting three phases for NPQ: (a) formation of zeaxanthin and antheraxanthin by the xanthophyll cycle; (b) formation of a state reflected by A530 that is induced by the transthylakoid ApH, possibly involving aggregation of LHCII; and (c) fluorescence quenching by the combined effect of both steps and by the H+-cation exchange properties of thylakoid membranes.

Sites of Action of Copper in the Photosynthetic Apparatus of Maize Leaves: Kinetic Analysis of Chlorophyll Fluorescence, Oxygen Evolution, Absorption Changes and Thermal Dissipation as Monitored by Photoacoustic Signals

1997 ◽  
Vol 24 (1) ◽  
pp. 81 ◽  
Author(s):  
Georgia Ouzounidou ◽  
Michael Moustakas ◽  
Reto J. Strasser
Keyword(s):  
Chlorophyll Fluorescence ◽  
Red Light ◽  
Photosynthetic Apparatus ◽  
Thermal Dissipation ◽  
Chlorophyll Fluorescence Induction ◽  
O2 Evolution ◽  
Reaction Centre ◽  
Maize Leaves ◽  
Sites Of Action

Fluorescence, absorbance and photoacoustic methods were used to examine in vivo various functional aspects of the photochemical apparatus of maize leaves exposed to different Cu concentrations. The primary photochemistry of a dark adapted leaf was less affected in the presence of Cu, while in a light-adapted leaf the photochemical events were severely impaired by Cu. Analysis of the characteristics of chlorophyll fluorescence induction revealed that the primary target of Cu stress involved the PSII reaction centre in its ability to adapt to high light conditions. Denaturation of PSII occured at 80 µM Cu resulting in a significant loss of PSII-mediated electron transport under continuous light and a strong inhibition of O2 evolution. It was also observed that PSI photochemistry, as probed by the photochemical energy storage in far-red light and the kinetics of P700 photooxidation by strong far- red light, was more tolerant to Cu compared to the PSII activity. Moreover, in Cu-exposed leaves irradiated with high intensity light, the in vivo heat emission yield increased due to the Cu deactivation of photosynthetic energy conservation. Heat release was well correlated with changes in non- photochemical quenching. Copper gradually prevents the adaptation process from a dark-adapted to a light-adapted state with the consequence that all observed photosynthetic activity criteria under steady state conditions in the light become more inefficient.

Growth and Photosynthetic Responses to Manganese and Copper Deficiencies in Wheat (Triticum aestivum) and Barley Grass (Hordeum glaucum and H. leporinum)

1988 ◽  
Vol 15 (3) ◽  
pp. 429 ◽  
Author(s):  
PE Kriedemann ◽  
JE Anderson
Keyword(s):  
Chlorophyll Fluorescence ◽  
Leaf Gas Exchange ◽  
Control Level ◽  
Co2 Exchange ◽  
Initial Slope ◽  
O2 Evolution ◽  
Mn Deficiency ◽  
Co2 Partial Pressure ◽  
In Vivo Chlorophyll Fluorescence

Wheat and barley grass were raised as seedlings in aerated solution cultures under high-pressure sodium vapour lamps in a growth cabinet. Manganese and copper were provided over a wide span of concentrations to induce a range in deficiency symptom expression. Plant response was documented in terms of biomass gain, in vivo chlorophyll fluorescence, CO2-saturated O2 evolution by leaf slices, single leaf H2O/CO2 exchange and A(pI) curves (assimilation as a function of intercellular CO2 partial pressure) at saturating light. Photosynthetic dysfunction due to trace element deficiency lowered O2 evolution (both area and chlorophyll basis) and slowed down leaf gas exchange. Both initial slope and CO2-saturated phases of A(pi) curves were similarly affected in the two species under either Cu or Mn deficiency. Induction kinetics of in vivo chlorophyll fluorescence proved distinctive for both species. Mn deficiency was often manifest as increased constant-yield (Fo) in combination with much reduced variable fluorescence (Fv). Increased ratio of Fo/ Fv was confirmed as a useful index for early diagnosis of Mn deficiency regardless of leaf Cu status. Barley grass (both H. glaucum Steud. and H. leporinum Link) was more tolerant of low Mn and Cu status than wheat, especially in terms of growth and photosynthetic response to Mn deficiency. Wheat plants made little growth once Mn supply was reduced to 10% of control level whereas barley grass was only moderately constrained.

Ultrastructural Correlations between Clonal Human Tumor Colonies and in Vivo Neoplasms

1982 ◽  
Vol 40 ◽  
pp. 210-211
Author(s):  
M.J. Murphy ◽  
R.R. Price ◽  
J.C. Sloman
Keyword(s):  
Cultured Cells ◽  
Human Tumor ◽  
Cell Type ◽  
Tumor Mass ◽  
Initial Cell ◽  
Cloning Assay ◽  
Human Tumor Cloning ◽  
The Relationship

The in vitro human tumor cloning assay originally described by Salmon and Hamburger has been applied recently to the investigation of differential anti-tumor drug sensitivities over a broad range of human neoplasms. A major problem in the acceptance of this technique has been the question of the relationship between the cultured cells and the original patient tumor, i.e., whether the colonies that develop derive from the neoplasm or from some other cell type within the initial cell population. A study of the ultrastructural morphology of the cultured cells vs. patient tumor has therefore been undertaken to resolve this question. Direct correlation was assured by division of a common tumor mass at surgical resection, one biopsy being fixed for TEM studies, the second being rapidly transported to the laboratory for culture.

Do Extra-Platelet Sources Contribute to the Plasma Level of Thrombospondin?

1988 ◽  
Vol 59 (02) ◽  
pp. 273-276 ◽  
Author(s):  
J Dawes ◽  
D A Pratt ◽  
M S Dewar ◽  
F E Preston
Keyword(s):  
Platelet Count ◽  
Background Concentration ◽  
Serum Concentrations ◽  
Bone Marrow Depression ◽  
Serial Sampling ◽  
Control Serum ◽  
Platelet Release ◽  
Highly Correlated ◽  
The Relationship

SummaryThrombospondin, a trimeric glycoprotein contained in the platelet α-granules, has been proposed as a marker of in vivo platelet activation. However, it is also synthesised by a range of other cells. The extraplatelet contribution to plasma levels of thrombospondin was therefore estimated by investigating the relationship between plasma thrombospondin levels and platelet count in samples from profoundly thrombocytopenic patients with marrow hypoplasia, using the platelet-specific α-granule protein β-thromboglobulin as control. Serum concentrations of both proteins were highly correlated with platelet count, but while plasma β-thromboglobulin levels and platelet count also correlated, there was no relationship between the number of platelets and thrombospondin concentrations in plasma. Serial sampling of patients recovering from bone marrow depression indicated that the plasma thrombospondin contributed by platelets is superimposed on a background concentration of at least 50 ng/ml probably derived from a non-platelet source, and plasma thrombospondin levels do not simply reflect platelet release.

Dose Requirement for Replacement Therapy in Hemophilia A

1979 ◽  
Vol 42 (03) ◽  
pp. 825-831 ◽  
Author(s):  
Jean-Pierre Allain
Keyword(s):  
Clinical Effect ◽  
Hemophilia A ◽  
Clinical Results ◽  
Severe Hemophilia ◽  
Dose Requirement ◽  
Viii Level ◽  
The Relationship ◽  
In Vivo Recovery ◽  
Different Doses

SummaryIn order to determine the correlation between different doses of F. VIII and their clinical effect,. 70 children with severe hemophilia A were studied after treatment with single doses of cryoprecipitate. The relationship between plasma F. VIII levels or doses calculated in u/ kg of body weight and clinical results followed an exponential curve. Plasma F. VIII levels of 0.35 and 0.53 u/ml corresponded to 95 and 99% satisfactory treatment, respectively. Similar clinical results were obtained with 20 and 31 u/kg. When the in vivo recovery of F. VIII after lyophilized cryoprecipitate was 0.015 u/ml for each u/kg injected, plasma F. VIII levels of 0.30 and 0.47 u/ml respectively were achieved. Since home treatment is largely based on single infusions of F. VIII, it is suggested that moderate and severe hemorrhages be treated with a dose which will provide a plasma F. VIII level of 0.5 u/ml.

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