Search results for "Chlorophyll"
showing 10 items of 453 documents
Chlorophyll a fluorescence in transplants of Parmelia sulcata Taylor near a power station (La Robla, León, Spain)
2006
Healthy thalli of Parmelia sulcata Taylor were transplanted to 8 localities in the surroundings of a power station (La Robla, León, Spain), the sole pollution source in the region. Changes in chlorophyll a fluorescence were monitored in the transplants 12 months, 18 months and 24 months after transplantation. Statistically significant differences were observed in the ratio of variable to maximal fluorescence, non-photochemical fluorescence quenching and vitality index. The decrease in fluorescence parameters was higher in the localities of Cuadros and Rabanal de Fenar, which are situated a few kilometres away from the power station and in the same direction as the prevailing winds.
Oxidative stress induces distinct physiological responses in the two Trebouxia phycobionts of the lichen Ramalina farinacea
2010
† Background and Aims Most lichens form associations with Trebouxia phycobionts and some of them simultaneously include genetically different algal lineages. In other symbiotic systems involving algae (e.g. reef corals), the relative abundances of different endosymbiotic algal clades may change over time. This process seems to provide a mechanism allowing the organism to respond to environmental stress. A similar mechanism may operate in lichens with more than one algal lineage, likewise protecting them against environmental stresses. Here, the physiological responses to oxidative stress of two distinct Trebouxia phycobionts (provisionally named TR1 and TR9) that coexist within the lichen R…
The organic air pollutant cumene hydroperoxide interferes with NOantioxidant role in rehydrating lichen
2013
Organic pollutants effects on lichens have not been addressed. Rehydration is critical for lichens, a burst of free radicals involving NO occurs. Repeated dehydrations with organic pollutants could increase oxidative damage. Our aim is to learn the effects of cumene hydroperoxide (CP) during lichen rehydration using Ramalina farinacea (L.) Ach., its photobiont Trebouxia spp. and Asterochloris erici. Confocal imaging shows intracellular ROS and NO production within myco and phycobionts, being the chloroplast the main source of free radicals. CP increases ROS, NO and lipid peroxidation and reduces chlorophyll autofluorescence, although photosynthesis remains unaffected. Concomitant NO inhibit…
Different strategies to achieve Pb-tolerance by the two Trebouxia algae coexisting in the lichen Ramalina farinacea.
2012
Lichen thalli are permeable to airborne substances, including heavy metals, which are harmful to cell metabolism. Ramalina farinacea shows a moderate tolerance to Pb. This lichen comprises two Trebouxia phycobionts, provisionally referred to as TR1 and TR9, with distinct physiological responses to acute oxidative stress. Thus, there is a more severe decay in photosynthesis and photosynthetic pigments in TR1 than in TR9. Similarly, under oxidative stress, antioxidant enzymes and HSP70 protein decrease in TR1 but increase in TR9. Since Pb toxicity is associated with increased ROS formation, we hypothesized greater Pb tolerance in this phycobiont. Accordingly, the aim of the present study was …
Preliminary assessment of terrestrial microalgae isolated from lichens as testing species for environmental monitoring: Lichen phycobionts present hi…
2013
Bioassays constitute a tool for pollution analysis providing a holistic approach and high-quality indication of the toxicity. Microbioassays allow evaluating the toxicity of many samples, implying lower costs and enabling routine monitoring and pollution control. But tests conducted so far are limited to the use of a small number of taxa. Lichens are excellent bioindicators of pollution with great ecological significance. Studies show that the phycobiont is more sensitive to pollutants than the mycobiont. Phycobiont have features such as adaptation to anhydrobiosis and relatively rapid growth in vitro, making them suitable for microbioassays. Our aim is to determine the sensitivity of phyco…
Multitemporal water quality study in Sitjar (Castelló, Spain) reservoir using Sentinel-2 images
2020
[EN] Water quality is a subject of intense scientific inquiry because of its repercussion in human’s life, agriculture or even energy generation. Remote sensing can be used to control water masses by analyzing biophysical variables. Chlorophyll-a (Chl-a) and Total Suspended Solids (SS) are a well-known feature of water quality. These variables have been measured in Sitjar reservoir (Castelló, Spain) as a part of the project Ecological Status of Aquatic Systems with Sentinel Satellites (ESAQS), in order to compare the results with satellite reflectance data. Two processes were compared to correct atmospherically the level 1C Sentinel 2 (S2) images. The results show that Case 2 Regional Coast…
Interference of tributyltin(IV)chloride on the vascular plant cells
2007
In the recent past years, interest in the environmental impact of organotin(IV) compounds has risen markedly. Considering that most data in the scientific literature refers to the animal kingdom and not to higher plants cells, we tested the effects of organotin compounds on vascular plant cells, by studying the interaction of tributyltin chloride (TBTCl) with Allium cepa, Solanun tuberosum and Solanum melongena, vascular plants that are directly involved in the human food chain. The TBTCl effects on mitotic metaphase plates, on pollen grains and on both microtubers and adult tuber parenchymatic cells were investigated and the concentrations of TBTCl inside the treated parenchymatic cells we…
TRACE ELEMENT BEHAVIOUR IN SEAWATER DURING PYROCLASTIC ETNA'S ACTIVITY IN 2001. CONCURRENT EFFECTS OF NUTRIENTS AND FORMATION OF ALTERATION MINERALS
2010
From July 13 2001 began the most intense Etna's eruptive activity in the last 300 years. While this phenomenon occurred the oceanographic cruise ANSIC 01 was carrying out. Therefore the unique opportunity is arisen to investigate the chemical effects on marine system of delivery of large amount of pyroclastic particles (about 1 g m-2) into seawater. Comparing collected trace element data with those analysed during the oceanographic cruise JUVENILE 99, carried out two years before, large enrichments in V, Cr, Mn, Fe, Co, Cu and Pb contents have been recognised and attributed to leaching of freshly-erupted volcanic ash. Further comparison between to-day and previous collected trace element da…
Simulation d'images d'un futur imageur multispectral géostationaire dédié à la couleur de l'eau : étude de l'influence des angles d'observation et d'…
2011
Improvements of optical sensors now make it possible to launch medium spatial and high spectral resolution sensors on the Geostationary Earth Orbit (GEO). The GEO allows sensors to observe the Earth with high temporal resolution, unlike Low Earth Orbit (LEO) satellites. The objective of this thesis is to simulate radiance images that would be provided by a theoretical ocean color sensor, on a geostationary orbit, in order to characterize the images to be acquired, to specify the future instruments and to validate the image processing algorithms. For this purpose, we have combined a radiative transfer model for ocean waters (Hydrolight) and a radiative transfer model for the atmosphere (MODT…
Oxidation Processes in Sicilian Olive Oils Investigated by a Combination of Optical and EPR Spectroscopy
2012
: Extra virgin olive oil (EVOO) is recognized as one of the healthiest foods for its high content of antioxidants, which forestall and slow down radical formation. Free radical-initiated oxidation is considered one of the main causes of rancidity in fats and oils. As a consequence, reliable protocols for the investigation of oil oxidation based on selective, noninvasive, and fast methods are highly desirable. Here we report an experimental approach based on UV-Vis absorbance, steady-state fluorescence, and electron paramagnetic resonance (EPR) spectroscopy for studying oxidation processes induced by temperature for a period up to 35 d on Sicilian EVOO samples. We followed the decrease in β…