Entity

Time filter

Source Type

Brno, Czech Republic

Alami M.,University of British Columbia | Lazar D.,Palacky University | Lazar D.,Global Change Research Center | Green B.R.,University of British Columbia
Biochimica et Biophysica Acta - Bioenergetics | Year: 2012

Aureococcus anophagefferens is a picoplanktonic microalga that is very well adapted to growth at low nutrient and low light levels, causing devastating blooms (brown tides) in estuarine waters. To study the factors involved in long-term acclimation to different light intensities, cells were acclimated for a number of generations to growth under low light (20 μmol photons m - 2 s- 1), medium light (60 or 90 μmol photons m - 2 s- 1) and high light (200 μmol photons m - 2 s- 1), and were analyzed for their contents of xanthophyll cycle carotenoids (the D pool), fucoxanthin and its derivatives (the F pool), Chls c2 and c3, and fucoxanthin Chl a/c polypeptides (FCPs). Higher growth light intensities resulted in increased steady state levels of both diadinoxanthin and diatoxanthin. However, it also resulted in the conversion of a significant fraction of fucoxanthin to 19′-butanoyloxyfucoxanthin without a change in the total F pool. The increase in 19′-butanoyloxyfucoxanthin was paralleled by a decrease in the effective antenna size, determined from the slope of the change in F 0 as a function of increasing light intensity. Transfer of acclimated cultures to a higher light intensity showed that the conversion of fucoxanthin to its derivative was a relatively slow process (time-frame of hours). We suggest the replacement of fucoxanthin with the bulkier 19′- butanoyloxyfucoxanthin results in a decrease in the light-harvesting efficiency of the FCP antenna and is part of the long-term acclimative response to growth at higher light intensities. © 2012 Elsevier Ltd. All rights reserved. Source


Guidolotti G.,CNR Institute of Agro-environmental and Forest Biology | Salviato M.,University of Padua | Calfapietra C.,CNR Institute of Agro-environmental and Forest Biology | Calfapietra C.,Global Change Research Center
Environmental Science and Pollution Research | Year: 2016

There is a growing interest to identify and quantify the benefits provided by the presence of trees in urban environment in order to improve the environmental quality in cities. However, the evaluation and estimate of plant efficiency in removing atmospheric pollutants is rather complicated, because of the high number of factors involved and the difficulty of estimating the effect of the interactions between the different components. In this study, the EMEP MSC-W model was implemented to scale-down to tree-level and allows its application to an industrial-urban green area in Northern Italy. Moreover, the annual outputs were compared with the outputs of UFORE (nowadays i-Tree), a leading model for urban forest applications. Although, EMEP/MSC-W model and UFORE are semi-empirical models designed for different applications, the comparison, based on O3, NO2 and PM10 removal, showed a good agreement in the estimates and highlights how the down-scaling methodology presented in this study may have significant opportunities for further developments. © 2016 Springer-Verlag Berlin Heidelberg Source


Fares S.,Italian Agricultural Research Council | Matteucci G.,National Research Council Italy | Matteucci G.,Institute for Agriculture and Forestry Systems in the Mediterranean | Scarascia Mugnozza G.,Italian Agricultural Research Council | And 7 more authors.
Atmospheric Environment | Year: 2013

Mediterranean forests close to urban areas are exposed to polluted plumes loaded with tropospheric ozone. This is the case of Castelporziano Estate, a 6000 ha Mediterranean forest 25 km from Rome downtown on the coast of the Mediterranean Sea. In September 2011 we started an intensive field campaign aimed at investigating ozone deposition from a mixed Mediterranean forest, mainly composed by Quercus suber, Quercus ilex, Pinus pinea. Measurements at canopy level with the eddy covariance technique were supported by a vegetation survey and the measurement of all environmental parameters which allowed to calculate stomatal ozone fluxes. Leaf-level measurements were used to parameterize models to calculate stomatal conductance based on a Jarvis-type and Ball-Berry approach. We show changes in magnitude of ozone fluxes from a warm (September) to a cold period (October-December). Stomatal component explained almost the totality of ozone fluxes during the cold days, but contributed only up to 50% to total ozone deposition during warm days, suggesting that other sinks (e.g. chemistry in the gas-phase) play a major role. Modeled stomatal ozone fluxes based on a Jarvis-type approach (DO3SE) correlated with measured fluxes better than using a Ball-Berry approach. A third model based on a modified Ball-Berry equation was proposed to account for the non-linear dependency of stomatal conductance on relative humidity. This research will help the development of metrics for ozone-risk assessment and advance our understanding of mixed Mediterranean forests in biosphere-atmosphere exchange. © 2012 Elsevier Ltd. Source


Calfapietra C.,CNR Institute of Agro-environmental and Forest Biology | Calfapietra C.,Global Change Research Center | Fares S.,Italian Agricultural Research Council | Manes F.,University of Rome La Sapienza | And 4 more authors.
Environmental Pollution | Year: 2013

Biogenic Volatile Organic Compounds (BVOC) play a critical role in biosphere-atmosphere interactions and are key factors of the physical and chemical properties of the atmosphere and climate. However, few studies have been carried out at urban level to investigate the interactions between BVOC emissions and ozone (O3) concentration. The contribution of urban vegetation to the load of BVOCs in the air and the interactions between biogenic emissions and urban pollution, including the likely formation of O3, needs to be investigated, but also the effects of O3 on the biochemical reactions and physiological conditions leading to BVOC emissions are largely unknown. The effect of BVOC emission on the O3 uptake by the trees is further complicating the interactions BVOC-O3, thus making challenging the estimation of the calculation of BVOC effect on O3 concentration at urban level. © 2013 Elsevier Ltd. All rights reserved. Source


Urban O.,Global Change Research Center | Hrstka M.,Brno University of Technology | Zitova M.,Global Change Research Center | Holisova P.,Global Change Research Center | And 7 more authors.
Plant Physiology and Biochemistry | Year: 2012

While downward photosynthetic acclimation in response to elevated CO2 (EC) is frequently accompanied by reduction in Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase), the exact mechanism behind this decrease and its dynamics are not well understood. We comprehensively studied Rubisco adjustment to EC in coniferous Picea abies using an electrophoretic (protein content), spectrophotometric (initial (RAinitial) and total (RAtotal) in vitro Rubisco activities), and gas-exchange (maximum carboxylation activity in vivo (VCmax)) techniques. With respect to differing carbon sink strength and nitrogen remobilization, we hypothesized greater acclimation of photosynthesis in one-year-old as compared to current-year needles and at the end than at the beginning of the vegetation season. EC treatment led to a decrease in VCmax values in current-year needles, but the ribulose-1,5-bisphosphate (RuBP)-limited rate of photosynthesis (Jmax) remained unaffected. Indeed, both VCmax and Jmax were reduced by the EC treatment in one-year-old needles. The extent of photosynthetic acclimation in EC plants did not increase, however, during the vegetation season. EC decreased the activation state of Rubisco (RAinitial/RAtotal) by 16% and 5% in current-year and one-year-old needles, respectively (averaged over the growing season). While during spring (short-term effect) EC treatment did not influence the Rubisco content per unit leaf area and decreased its specific activity (activity per unit Rubisco mass) in both needle age classes studied, exposure to EC during the entire vegetation season tended to reduce the Rubisco content while increasing its specific activity. Irrespective of CO2 treatment and needle age, a hyperbolic-decay relationship was observed between Rubisco-specific activity and its content. © 2012 Elsevier Masson SAS. Source

Discover hidden collaborations