carbon allocation Dotaz Zobrazit nápovědu
Stem respiration is an important component of an ecosystem's carbon budget. Beside environmental factors, it depends highly on tree energy demands for stem growth. Determination of the relationship between stem growth and stem respiration would help to reveal the response of stem respiration to changing climate, which is expected to substantially affect tree growth. Common measurement of stem radial increment does not record all aspects of stem growth processes, especially those connected with cell wall thickening; therefore, the relationship between stem respiration and stem radial increment may vary depending on the wood cell growth differentiation phase. This study presents results from measurements of stem respiration and increment carried out for seven growing seasons in a young Norway spruce forest. Moreover, rates of carbon allocation to stems were modeled for these years. Stem respiration was divided into maintenance (Rm) and growth respiration (Rg) based upon the mature tissue method. There was a close relationship between Rg and daily stem radial increment (dSRI), and this relationship differed before and after dSRI seasonal maximum, which was around 19 June. Before this date, Rg increased exponentially with dSRI, while after this date logarithmically. This is a result of later maxima of Rg and its slower decrease when compared with dSRI, which is connected with energy demands for cell wall thickening. Rg reached a maxima at the end of June or in July. The maximum of carbon allocation to stem peaked in late summer, when Rg mostly tended to decrease. The overall contribution of Rg to stem CO2 efflux amounted to 46.9% for the growing period from May to September and 38.2% for the year as a whole. This study shows that further deeper analysis of in situ stem growth and stem respiration dynamics is greatly needed, especially with a focus on wood formation on a cell level.
- MeSH
- alokace zdrojů MeSH
- ekosystém MeSH
- oxid uhličitý MeSH
- roční období MeSH
- smrk * MeSH
- stonky rostlin MeSH
- stromy MeSH
- uhlík MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Norsko MeSH
Carbon allocation plays a key role in ecosystem dynamics and plant adaptation to changing environmental conditions. Hence, proper description of this process in vegetation models is crucial for the simulations of the impact of climate change on carbon cycling in forests. Here we review how carbon allocation modelling is currently implemented in 31 contrasting models to identify the main gaps compared with our theoretical and empirical understanding of carbon allocation. A hybrid approach based on combining several principles and/or types of carbon allocation modelling prevailed in the examined models, while physiologically more sophisticated approaches were used less often than empirical ones. The analysis revealed that, although the number of carbon allocation studies over the past 10 years has substantially increased, some background processes are still insufficiently understood and some issues in models are frequently poorly represented, oversimplified or even omitted. Hence, current challenges for carbon allocation modelling in forest ecosystems are (i) to overcome remaining limits in process understanding, particularly regarding the impact of disturbances on carbon allocation, accumulation and utilization of nonstructural carbohydrates, and carbon use by symbionts, and (ii) to implement existing knowledge of carbon allocation into defence, regeneration and improved resource uptake in order to better account for changing environmental conditions.
- MeSH
- ekosystém * MeSH
- klimatické změny * MeSH
- koloběh uhlíku MeSH
- lesy MeSH
- uhlík MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
Chromera velia is a marine photosynthetic relative of human apicomplexan parasites. It has been isolated from coral reefs and is indicted for being involved in symbioses with hermatypic corals. C. velia has been subject to intensive research, but still very little is known of its response to light quality and quantity. Here, we have studied the growth and compositional responses of C. velia to culture under monochromatic light (blue, green or red), at two photon flux densities (PFD, 20 and 100 μmol photons m-2 s-1). Our results show that C. velia growth rate is unaffected by the quality of light, whereas it responds to PFD. However, light quality influenced cell size, which was smaller for cells exposed to blue monochromatic light, regardless of PFD. PFD strongly influenced carbon allocation: at 20 μmol photons m-2 s-1, carbon was mainly allocated into proteins while at 100 μmol photons m-2 s-1, carbon was allocated mainly into carbohydrate and lipid pools. The blue light treatment caused a decrease in the lipids and carbohydrates to proteins and thus suggested to affect nitrogen metabolism in acclimated cells. Whole-cell absorption spectra revealed the existence of red-shifted chlorophyll a antenna not only under red light but in all low PFD treatments. These findings show the ability of C. velia to successfully adapt and thrive in spectrally very different environments of coral reefs.
Quantification of carbon (C) fluxes in mycorrhizal plants is one of the important yet little explored tasks of mycorrhizal physiology and ecology. (13)CO2 pulse-chase labelling experiments are increasingly being used to track the fate of C in these plant-microbial symbioses. Nevertheless, continuous monitoring of both the below- and aboveground CO2 emissions remains a challenge, although it is necessary to establish the full C budget of mycorrhizal plants. Here, a novel CO2 collection system is presented which allows assessment of gaseous CO2 emissions (including isotopic composition of their C) from both belowground and shoot compartments. This system then is used to quantify the allocation of recently fixed C in mycorrhizal versus nonmycorrhizal Medicago truncatula plants with comparable biomass and mineral nutrition. Using this system, we confirmed substantially greater belowground C drain in mycorrhizal versus nonmycorrhizal plants, with the belowground CO2 emissions showing large variation because of fluctuating environmental conditions in the glasshouse. Based on the assembled (13)C budget, the C allocation to the mycorrhizal fungus was between 2.3% (increased (13)C allocation to mycorrhizal substrate) and 2.9% (reduction of (13)C allocation to mycorrhizal shoots) of the plant gross photosynthetic production. Although the C allocation to shoot respiration (measured during one night only) did not differ between the mycorrhizal and nonmycorrhizal plants under our experimental conditions, it presented a substantial part (∼10%) of the plant C budget, comparable to the amount of CO2 released belowground. These results advocate quantification of both above- and belowground CO2 emissions in future studies.
- MeSH
- fotosyntéza fyziologie MeSH
- Glomeromycota fyziologie MeSH
- kořeny rostlin metabolismus MeSH
- Medicago truncatula metabolismus mikrobiologie MeSH
- mykorhiza metabolismus MeSH
- oxid uhličitý chemie metabolismus MeSH
- uhlík metabolismus MeSH
- výhonky rostlin metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
Endosymbioses necessitate functional cooperation of cellular compartments to avoid pathway redundancy and streamline the control of biological processes. To gain insight into the metabolic compartmentation in chromerids, phototrophic relatives to apicomplexan parasites, we prepared a reference set of proteins probably localized to mitochondria, cytosol, and the plastid, taking advantage of available genomic and transcriptomic data. Training of prediction algorithms with the reference set now allows a genome-wide analysis of protein localization in Chromera velia and Vitrella brassicaformis. We confirm that the chromerid plastids house enzymatic pathways needed for their maintenance and photosynthetic activity, but for carbon and nitrogen allocation, metabolite exchange is necessary with the cytosol and mitochondria. This indeed suggests that the regulatory mechanisms operate in the cytosol to control carbon metabolism based on the availability of both light and nutrients. We discuss that this arrangement is largely shared with apicomplexans and dinoflagellates, possibly stemming from a common ancestral metabolic architecture, and supports the mixotrophy of the chromerid algae.
- MeSH
- algoritmy MeSH
- Alveolata metabolismus MeSH
- cytosol metabolismus MeSH
- dusík metabolismus MeSH
- fotosyntéza genetika fyziologie MeSH
- fylogeneze MeSH
- molekulární evoluce MeSH
- symbióza genetika fyziologie MeSH
- uhlík metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
We studied cell properties including carbon allocation dynamics in the globally abundant and important cyanobacterium Prochlorococcus marinus strain PCC 9511 grown at three different growth rates in nitrogen-limited continuous cultures. With increasing nitrogen limitation, cellular divinyl chlorophyll a and the functional absorption cross section of Photosystem II decreased, although maximal photosynthetic efficiency of PSII remained unaltered across all N-limited growth rates. Chl-specific gross and net carbon primary production were also invariant with nutrient-limited growth rate, but only 20% of Chl-specific gross carbon primary production was retained in the biomass across all growth rates. In nitrogen-replete cells, 60% of the assimilated carbon was incorporated into the protein pool while only 30% was incorporated into carbohydrates. As N limitation increased, new carbon became evenly distributed between these two pools. While many of these physiological traits are similar to those measured in other algae, there are also distinct differences, particularly the lower overall efficiency of carbon utilization. The latter provides new information needed for understanding and estimating primary production, particularly in the nutrient-limited tropical oceans where P. marinus dominates phytoplankton community composition.
- MeSH
- dusík metabolismus MeSH
- Prochlorococcus metabolismus MeSH
- sinice metabolismus MeSH
- uhlík metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
Cities utilize and manipulate an immense amount of global carbon flows through their economic and technical activities. Here, we establish the carbon networks of eight global cities by tracking the carbon exchanges between various natural and economic components. The metabolic properties of these carbon networks are compared by combining flow-based and interpretative network metrics. We further assess the relations of these carbon metabolic properties of cities with their socioeconomic attributes that are deemed important in urban development and planning. We find that, although there is a large difference in city-level carbon balance and flow pattern, a similarity in intercomponent relationships and metabolic characteristicsdoes exist. Cities with lower per capita carbon emissions tend to have healthier metabolic systems with more cooperative resource allocation among various industries, which indicates that there may be synergy between urban decarbonization and carbon-containing resource system optimization. A combination of indicators from flow balance and network models is a promising scheme for linking sector-based carbon inventories to system-based simulations of carbon management efforts. With this done, we may be able to reduce the knowledge gap with respect to how various carbon flows in cities can be concertedly managed considering both the restraint from their climate mitigation goals as well as the impact on urban social and economic development.
- MeSH
- ekonomický rozvoj MeSH
- obnova měst * MeSH
- oxid uhličitý analýza MeSH
- uhlík * MeSH
- velkoměsta MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- velkoměsta MeSH
Photoautotrophic growth depends upon an optimal allocation of finite cellular resources to diverse intracellular processes. Commitment of a certain mass fraction of the proteome to a specific cellular function typically reduces the proteome available for other cellular functions. Here, we develop a semi-quantitative kinetic model of cyanobacterial phototrophic growth to describe such trade-offs of cellular protein allocation. The model is based on coarse-grained descriptions of key cellular processes, in particular carbon uptake, metabolism, photosynthesis, and protein translation. The model is parameterized using literature data and experimentally obtained growth curves. Of particular interest are the resulting cyanobacterial growth laws as fundamental characteristics of cellular growth. We show that the model gives rise to similar growth laws as observed for heterotrophic organisms, with several important differences due to the distinction between light energy and carbon uptake. We discuss recent experimental data supporting the model results and show that coarse-grained growth models have implications for our understanding of the limits of phototrophic growth and bridge a gap between molecular physiology and ecology.
The assimilation of N-NO3- requires more energy than that of N-NH4+ . This becomes relevant when energy is limiting and may impinge differently on cell energy budget depending on depth, time of the day and season. We hypothesize that N-limited and energy-limited cells of the oceanic cyanobacterium Synechococcus sp. differ in their response to the N source with respect to growth, elemental stoichiometry and carbon allocation. Under N limitation, cells retained almost absolute homeostasis of elemental and organic composition, and the use of NH4+ did not stimulate growth. When energy was limiting, however, Synechococcus grew faster in NH4+ than in NO3- and had higher C (20%), N (38%) and S (30%) cell quotas. Furthermore, more C was allocated to protein, whereas the carbohydrate and lipid pool size did not change appreciably. Energy limitation also led to a higher photosynthetic rate relative to N limitation. We interpret these results as an indication that, under energy limitation, the use of the least expensive N source allowed a spillover of the energy saved from N assimilation to the assimilation of other nutrients. The change in elemental stoichiometry influenced C allocation, inducing an increase in cell protein, which resulted in a stimulation of photosynthesis and growth.
- MeSH
- adenosintrifosfát metabolismus MeSH
- amoniové sloučeniny farmakologie MeSH
- bakteriální proteiny metabolismus MeSH
- biomasa MeSH
- dusičnany farmakologie MeSH
- dusík metabolismus MeSH
- energetický metabolismus * účinky léků MeSH
- fosfor metabolismus MeSH
- fotosyntéza účinky léků MeSH
- kyslík metabolismus MeSH
- lipidy analýza MeSH
- sacharidy analýza MeSH
- síra metabolismus MeSH
- Synechococcus cytologie účinky léků růst a vývoj metabolismus MeSH
- uhlík metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
This research deals with the removal of Cr(VI), one of the most toxic heavy metal in biological systems, from wastewater by using activated carbon produced via pyrolysis and chemical activation of "Posidonia oceanica". That is the most important and well-studied seagrass species of the Mediterranean Sea. The as produced activated carbon exhibited high specific surface area up to 1563 m2/g and a cumulative pore volume of 0.74 cm3/g, allocated to 74% micro-pores and 26% to meso-macro- pores. The adsorption capacity of Cr(VI) into Posidonia oceanica activated carbon was studied via batch experiments considering the contact time, the initial concentration and the pH parameters. The results were interpreted using four different adsorption kinetic models. The activated carbon material seems to exhibit excellent sorption properties with rapid removal capability for Cr(VI). The estimated maximum uptake capacity at equilibrium stage was ~120 mg/g. Also, the initial adsorption rate ri was dependent on the initial Cr(VI) concentration in aqueous solution and it was from 77 mg/(g*h) to 264 mg/(g*h). The best fitted kinetic model seems to be the Diffusion-Chemisorption model with the rate constant KDC of the Cr(VI) ions transfer from liquid to solid particles extend from 52 to 78 mg/(g*h0.5).
- MeSH
- adsorpce MeSH
- Alismatales * MeSH
- chemické látky znečišťující vodu * analýza MeSH
- chrom analýza MeSH
- dřevěné a živočišné uhlí MeSH
- kinetika MeSH
- koncentrace vodíkových iontů MeSH
- pyrolýza MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Středozemní moře MeSH
