Search results for "Chlorophyll"

Effects of UVB radiation exposure from the molecular to the organism level in macrophytes from shallow Mediterranean habitats

2015

Abstract The available data on the effects of UVB radiation (UVBR) are scarce for submerged macrophytes, particularly charophytes. We studied the effects of UVBR on Chara baltica, Chara hispida, Chara vulgaris, Nitella hyalina and Myriophyllum spicatum, collected from shallow Mediterranean waterbodies. In a short-term laboratory experiment, we subjected these species to three different UVBR treatments corresponding to daily biologically effective integrated doses of 0, 1 and 6 kJ m−2. The analysed response variables were DNA damage, UV-absorbing compounds (both the methanol-soluble–SUVACs- and, for the first time in charophytes, the methanol-insoluble cell wall-bound fraction–WUVACs-), the …

Pigment ligation to proteins of the photosynthetic apparatus in higher plants

1997

Ligation of pigments to proteins of the thylakoid membrane is a central step in the assembly of the photosynthetic apparatus in higher plants. Because of the potentially damaging photooxidative activity of chlorophylls, it is likely that between their biosynthesis and final assembly, chlorophylls will always be bound to protein complexes in which photooxidation is prevented by quenchers such as carotenoids. Such complexes may include chlorophyll carriers and/or membrane receptors involved in protein insertion into the membrane. Many if not all pigment-protein complexes of the thylakoid are stabilised towards protease attack by bound pigments. The major light-harvesting chlorophyll a/b prote…

2019

Water-soluble chlorophyll proteins (WSCP) from Brassicaceae form homotetrameric chlorophyll (Chl)–protein complexes binding one Chl per apoprotein and no carotenoids. Despite the lack of photoprotecting pigments, the complex-bound Chls displays a remarkable stability toward photodynamic damage. On the basis of a mutational study, we show that not only the presence of the phytyls is necessary for photoprotection in WSCPs, as we previously demonstrated, but also is their correct conformation and localization. The extreme heat stability of WSCP also depends on the presence of the phytyl chains, confirming their relevance for the unusual stability of WSCP.

Effect of Ti(IY) on some indicators of physiological activity inCapsicum annuum, L.

1994

SummaryPaprika pepper (Capsicum annuum, L., cv. Negral) plants grown in a greenhouse were supplied Ti(IV) ascorbate through the roots or through leaves. Biomass production, peroxidase (donor: H2O, oxidoreductase; EC 1.11.1.7) activity, and malic acid, starch and chlorophyll concentrations were determined in different plant organs. It was observed that Ti increased the concentration of some of the metabolites studied and promoted both peroxidase activity and biomass production. The profitable effect of the Ti treatments could occur because they enhance the availability of other nutrients. This effect could be due to the low redox potential of the Ti+3/Ti+4 system that catalyzes the activity …

Iodine containing species in the remote marine boundary layer: A link to oceanic phytoplankton

2011

[1] Iodine containing species have been measured in the particle phase (PM2.5) and the gas phase during a ship campaign between January and February 2007 in the South Atlantic marine boundary layer (MBL). Methyl iodide (CH3I) in the gas phase and soluble iodine species, i.e. iodide, iodate and an unidentified organic iodine species (UOI), in PM2.5 were measured. Temporal variations of gaseous and particulate iodine species were investigated. The exposure of the sampled air masses to phytoplankton along the back-trajectories was studied using a lagrangian transport model and satellite observations of oceanic chlorophyll-a concentration. Significant correlations were found between the concent…

Analysis and Reconstitution of Chlorophyll-Proteins

2003

Retrieval of chlorophyll content and LAI of crops using hyperspectral techniques: application to PROBA/CHRIS data

2008

Hyperspectral/multiangular data allow the retrieval of important vegetation properties at canopy level, such as the Leaf Area Index (LAI) and Leaf Chlorophyll Content. Current methods are based on the relationship between biophysical properties and retrievals from those spectral bands (from the complete hyperspectral/multiangular information) where specific absorption features are present within the considered spectral range. Furthermore, new sensors such as PROBA/CHRIS provide continuous hyperspectral reflectance measurements that can be considered as a continuous function of wavelength. The mathematical analysis of these continuous functions allows a new way of exploiting the relationship…

The Interaction of State Transitions and Chlororespiration in the Xanthophycean Alga Pleurochloris Meiringensis

1990

Wavelength dependent State I-State II-transitions have been shown to exist in chlorophytes and red algae. Little is known about the regulation of energy distribution between the photosystems of chlorophyll c-containing plants. Previously it was shown that in the xanthophycean alga Pleurochloris meiringensis two states of energy distribution could be established [l]: In state “D” light is preferentially transferred to PS II, whereas in state “L” PS I is favoured. These state regulations strictly depend on the intensity and not on the wavelength of prei1lumination. In this paper we give new evidence that chlororespiration is involved in the mechanism of state “L”-state “D”-transitions.

Diagnosis of Damage to Norway Spruce (Picea Abies) through Ethylene and Other Biochemical Criteria

1998

Forest damage normally is characterized by loss and yellowing of leaves or needles. The results of this ocular damage diagnosis can be confirmed and stated more precisely through biochemical criteria, e.g. the plant hormone ethylene, the activity of the enzyme phosphoenolpyruvate-carboxylase (PEP-C), the content of chlorophyll and other biochemical parameters. Therefore we investigated the interrelation between visible damage and 13 biochemical parameters in six trees each from eleven permanent observed sites in the south-west of Germany. The results indicate that damaged trees can be separated clearly from undamaged trees by these biochemical criteria. Furthermore, statistical evaluation o…

Evaluation of remote sensing of vegetation fluorescence by the analysis of diurnal cycles

2008

Chlorophyll fluorescence (ChF) emission is a direct indicator of the photosynthetic activity of vegetation, which is a key parameter of the carbon cycle. This paper analyses chlorophyll fluorescence evolution at leaf level during a complete diurnal cycle in simulated and natural conditions, for two species under different stress conditions. Absolute spectral radiance of the ChF emission is obtained allowing a quantitative derivation of the fluorescence yield of the ChF, which correlates well with established fluorescence instruments. The studied cases show that the ChF emission is mainly driven by the photosynthetic active radiation during the whole cycle, but the fluorescence yield is seve…