Differences in the capacity for radiationless energy dissipation in the photochemical apparatus of green and blue-green algal lichens associated with differences in carotenoid composition.
Summary of "Differences in the capacity for radiationless energy dissipation in the photochemical apparatus of green and blue-green algal lichens associated with differences in carotenoid composition."
Green algal lichens, which were able to form zeaxanthin rapidly via the de-epoxidation of violaxanthin, exhibited a high capacity to dissipate excess excitation energy nonradiatively in the antenna chlorophyll as indicated by the development of strong nonphotochemical quenching of chlorophyll fluorescence (FM, the maximum yield of fluorescence induced by pulses of saturating light) and, to a lesser extent, FO (the yield of instantaneous fluorescence). Blue-green algal lichens which did not contain any zeaxanthin were incapable of such radiationless energy dissipation and were unable to maintain the acceptor of photosystem II in a low reduction state upon exposure to excessive photon flux densities (PFD). Furthermore, following treatment of the thalli with an inhibitor of the violaxanthin de-epoxidase, dithiothreitol, the response of green algal lichens to light became very similar to that of the blue-green algal lichens. Conversely, blue-green algal lichens which had accumulated some zeaxanthin following long-term exposure to higher PFDs exhibited a response to light which was intermediate between that of zeaxanthin-free blue-green algal lichens and zeaxanthin-containing green algal lichens. Zeaxanthin can apparently be formed in blue-green algal lichens (which lack the xanthophyll epoxides, i.e. violaxanthin and antheraxanthin) as part of the normal biosynthetic pathway which leads to a variety of oxygenated derivatives of β-carotene during exposure to high light over several days. We conclude that the pronounced difference in the capacity for photoprotective energy dissipation in the antenna chlorophyll between (zeaxanthin-containing0 green algal lichens and (zeaxanthin-free) blue-green algal lichens is related to the presence or absence of zeaxanthin, and that this difference can explain the greater susceptibility to high-light stress in lichens with blue-green phycobionts.
Institut für Botanik und Pharmazeutische Biologie, Universität Würzburg, Mittlerer Dallenbergweg 64, D-8700, Würzburg, Germany.
This article was published in the following journal.
The possibility that zeaxanthin mediates the dissipation of an excess of excitation energy in the antenna chlorophyll of the photochemical apparatus has been tested through the use of an inhibitor of ...
It has been suggested previously that non-photochemical quenching of chlorophyll fluorescence is associated with a decrease in the rate of photosystem 2 (PS 2) photochemistry. In this study analyses o...
The relaxation of the non-photochemical quenching of chlorophyll fluorescence has been investigated in cells of the green alga Dunaliella following illumination. The relaxation after the addition of D...
The fluorescence kinetics of both intact needles and isolated chloroplasts of summer active and winter stressed Pinus sylvestris were measured at both room temperature and 77 K. It was confirmed that ...
The light-harvesting antenna of higher plant photosystem II has an intrinsic capability for self-defence against intense sunlight. The thermal dissipation of excess energy can be measured as the non-p...
To demonstrate differences in response of subjects with a high, low or medium predisposition for weight regain after weight reduction in terms of: body composition; energy expenditure; phy...
The purpose of this study is to determine whether green tea may lower the risk of certain cancers.
Dysmenorrhoea (menstrual pain) is a common complaint among women, leading to use of analgesics, reduced quality of life, and interference with daily activities such as going to work or sch...
The broad aim of this study is to evaluate the efficacy of photochemical tissue bonding (PTB) for the closure of skin excisions. We will test the hypothesis that full thickness skin excisi...
The investigators aim to study the effects of green tea and maté consumption on lipid and inflammatory profiles in dyslipidemic and overweight subjects.
Medical and Biotech [MESH] Definitions
Rate of energy dissipation along the path of charged particles. In radiobiology and health physics, exposure is measured in kiloelectron volts per micrometer of tissue (keV/micrometer T).
Processes by which phototrophic organisms use sunlight as their primary energy source. Contrasts with chemotrophic processes which do not depend on light and function in deriving energy from exogenous chemical sources. Photoautotrophy (or photolithotrophy) is the ability to use sunlight as energy to fix inorganic nutrients to be used for other organic requirements. Photoautotrophs include all green plants, GREEN ALGAE; CYANOBACTERIA, and green and PURPLE SULFUR BACTERIA. Photoheterotrophs or photoorganotrophs require a supply of organic nutrients for their organic requirements but use sunlight as their primary energy source; examples include certain PURPLE NONSULFUR BACTERIA. Depending on environmental conditions some organisms can switch between different nutritional modes (AUTOTROPHY; HETEROTROPHY; chemotrophy; or phototrophy) to utilize different sources to meet their nutrients and energy requirements.
A copper-containing plant protein that is a fundamental link in the electron transport chain of green plants during the photosynthetic conversion of light energy by photophosphorylation into the potential energy of chemical bonds.
Polyunsaturated side-chain quinone derivative which is an important link in the electron transport chain of green plants during the photosynthetic conversion of light energy by photophosphorylation into the potential energy of chemical bonds.
Electric power supply devices which convert biological energy, such as chemical energy of metabolism or mechanical energy of periodic movements, into electrical energy.