| 1. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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| 2. |
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| 3. |
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| 4. |
- Peters, W., et al.
(författare)
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Seven years of recent European net terrestrial carbon dioxide exchange constrained by atmospheric observations
- 2010
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 16:4, s. 1317-1337
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Tidskriftsartikel (refereegranskat)abstract
- We present an estimate of net ecosystem exchange (NEE) of CO2 in Europe for the years 2001-2007. It is derived with a data assimilation that uses a large set of atmospheric CO2 mole fraction observations (similar to 70 000) to guide relatively simple descriptions of terrestrial and oceanic net exchange, while fossil fuel and fire emissions are prescribed. Weekly terrestrial sources and sinks are optimized (i.e., a flux inversion) for a set of 18 large ecosystems across Europe in which prescribed climate, weather, and surface characteristics introduce finer scale gradients. We find that the terrestrial biosphere in Europe absorbed a net average of -165 Tg C yr-1 over the period considered. This uptake is predominantly in non-EU countries, and is found in the northern coniferous (-94 Tg C yr-1) and mixed forests (-30 Tg C yr-1) as well as the forest/field complexes of eastern Europe (-85 Tg C yr-1). An optimistic uncertainty estimate derived using three biosphere models suggests the uptake to be in a range of -122 to -258 Tg C yr-1, while a more conservative estimate derived from the a-posteriori covariance estimates is -165 +/- 437 Tg C yr-1. Note, however, that uncertainties are hard to estimate given the nature of the system and are likely to be significantly larger than this. Interannual variability in NEE includes a reduction in uptake due to the 2003 drought followed by 3 years of more than average uptake. The largest anomaly of NEE occurred in 2005 concurrent with increased seasonal cycles of observed CO2. We speculate these changes to result from the strong negative phase of the North Atlantic Oscillation in 2005 that lead to favorable summer growth conditions, and altered horizontal and vertical mixing in the atmosphere. All our results are available through http://www.carbontracker.eu.
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| 5. |
- Cassetta, L, et al.
(författare)
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Differential expansion of circulating human MDSC subsets in patients with cancer, infection and inflammation
- 2020
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Ingår i: Journal for immunotherapy of cancer. - : BMJ. - 2051-1426. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- Myeloid-derived suppressor cells (MDSC) are a functional myeloid cell subset that includes myeloid cells with immune suppressive properties. The presence of MDSC has been reported in the peripheral blood of patients with several malignant and non-malignant diseases. So far, direct comparison of MDSC across different diseases and Centers is hindered by technical pitfalls and a lack of standardized methodology. To overcome this issue, we formed a network through the COST Action Mye-EUNITER (www.mye-euniter.eu) with the goal to standardize and facilitate the comparative analysis of human circulating MDSC in cancer, inflammation and infection. In this manuscript, we present the results of the multicenter study Mye-EUNITER MDSC Monitoring Initiative, that involved 13 laboratories and compared circulating MDSC subsets across multiple diseases, using a common protocol for the isolation, identification and characterization of these cells.MethodsWe developed, tested, executed and optimized a standard operating procedure for the isolation and immunophenotyping of MDSC using blood from healthy donors. We applied this procedure to the blood of almost 400 patients and controls with different solid tumors and non-malignant diseases. The latter included viral infections such as HIV and hepatitis B virus, but also psoriasis and cardiovascular disorders.ResultsWe observed that the frequency of MDSC in healthy donors varied substantially between centers and was influenced by technical aspects such as the anticoagulant and separation method used. Expansion of polymorphonuclear (PMN)-MDSC exceeded the expansion of monocytic MDSC (M-MDSC) in five out of six solid tumors. PMN-MDSC expansion was more pronounced in cancer compared with infection and inflammation. Programmed death-ligand 1 was primarily expressed in M-MDSC and e-MDSC and was not upregulated as a consequence of disease. LOX-1 expression was confined to PMN-MDSC.ConclusionsThis study provides improved technical protocols and workflows for the multi-center analysis of circulating human MDSC subsets. Application of these workflows revealed a predominant expansion of PMN-MDSC in solid tumors that exceeds expansion in chronic infection and inflammation.
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| 6. |
- Gladyshev, VN, et al.
(författare)
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Selenoprotein Gene Nomenclature
- 2016
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Ingår i: The Journal of biological chemistry. - 1083-351X. ; 291:46, s. 24036-24040
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Tidskriftsartikel (refereegranskat)
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| 7. |
- Hofer, M., et al.
(författare)
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International periodic fever, aphthous stomatitis, pharyngitis, cervical adenitis syndrome cohort: description of distinct phenotypes in 301 patients
- 2014
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Ingår i: Rheumatology. - : Oxford University Press (OUP). - 1462-0324 .- 1462-0332. ; 53:6, s. 1125-1129
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. The aims of this study were to describe the clinical features of periodic fever, aphthous stomatitis, pharyngitis and cervical adenitis (PFAPA) and identify distinct phenotypes in a large cohort of patients from different countries. Methods. We established a web-based multicentre cohort through an international collaboration within the periodic fevers working party of the Pediatric Rheumatology European Society (PReS). The inclusion criterion was a diagnosis of PFAPA given by an experienced paediatric rheumatologist participating in an international working group on periodic fever syndromes. Results. Of the 301 patients included from the 15 centres, 271 had pharyngitis, 236 cervical adenitis, 171 oral aphthosis and 132 with all three clinical features. A total of 228 patients presented with additional symptoms (131 gastrointestinal symptoms, 86 arthralgias and/or myalgias, 36 skin rashes, 8 neurological symptoms). Thirty-one patients had disease onset after 5 years and they reported more additional symptoms. A positive family history for recurrent fever or recurrent tonsillitis was found in 81 patients (26.9%). Genetic testing for monogenic periodic fever syndromes was performed on 111 patients, who reported fewer occurrences of oral aphthosis or additional symptoms. Twenty-four patients reported symptoms (oral aphthosis and malaise) outside the flares. The CRP was >50 mg/l in the majority (131/190) of the patients tested during the fever. Conclusion. We describe the largest cohort of PFAPA patients presented so far. We confirm that PFAPA may present with varied clinical manifestations and we show the limitations of the commonly used diagnostic criteria. Based on detailed analysis of this cohort, a consensus definition of PFAPA with better-defined criteria should be proposed.
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| 8. |
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| 9. |
- Rybicka, M., et al.
(författare)
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Late Tripolye Culture Settlement Spatial Pattering : Case study from the Gordineşti II-Stînca goală site, Northern Moldova
- 2023
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Ingår i: Praehistoriche Zeitschrift. - 0079-4848 .- 1613-0804. ; 98:2, s. 538-556
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Tidskriftsartikel (refereegranskat)abstract
- The Gordineşti II-Stînca goală is an archaeological site located in the northern part of the Moldavian Plateau in Edineț Region. Chronologically this settlement is linked to the later phase of the Tripolye Culture. Currently, in archaeological literature, the problems of human occupation, land management, and spatial arrangement of settlements in Moldova during the Eneolithic are highly understudied. In this paper, we present the results of recent archaeological works focusing on the spatial patterning of housing structures, Ground Penetrating Radar (GPR) survey, and desk-based Kernel Density Estimation (KDE) analysis, that has been undertaken to further the understanding of the spatial organisation of the Gordineşti II-Stînca goală settlement. The results indicate the high archaeological potential of this site, with the likely presence of multiple housing structures arranged in a planned and functional manner.
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| 10. |
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| 11. |
- Dirks-Mulder, Anita, et al.
(författare)
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Exploring the evolutionary origin of floral organs of Erycina pusilla, an emerging orchid model system
- 2017
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Ingår i: BMC Evolutionary Biology. - : BIOMED CENTRAL LTD. - 1471-2148. ; 17
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Tidskriftsartikel (refereegranskat)abstract
- Background: Thousands of flowering plant species attract pollinators without offering rewards, but the evolution of this deceit is poorly understood. Rewardless flowers of the orchid Erycina pusilla have an enlarged median sepal and incised median petal ('lip') to attract oil-collecting bees. These bees also forage on similar looking but rewarding Malpighiaceae flowers that have five unequally sized petals and gland-carrying sepals. The lip of E. pusilla has a 'callus' that, together with winged 'stelidia', mimics these glands. Different hypotheses exist about the evolutionary origin of the median sepal, callus and stelidia of orchid flowers. Results: The evolutionary origin of these organs was investigated using a combination of morphological, molecular and phylogenetic techniques to a developmental series of floral buds of E. pusilla. The vascular bundle of the median sepal indicates it is a first whorl organ but its convex epidermal cells reflect convergence of petaloid features. Expression of AGL6 EpMADS4 and APETALA3 EpMADS14 is low in the median sepal, possibly correlating with its petaloid appearance. A vascular bundle indicating second whorl derivation leads to the lip. AGL6 EpMADS5 and APETALA3 EpMADS13 are most highly expressed in lip and callus, consistent with current models for lip identity. Six vascular bundles, indicating a stamen-derived origin, lead to the callus, stelidia and stamen. AGAMOUS is not expressed in the callus, consistent with its sterilization. Out of three copies of AGAMOUS and four copies of SEPALLATA, EpMADS22 and EpMADS6 are most highly expressed in the stamen. Another copy of AGAMOUS, EpMADS20, and the single copy of SEEDSTICK, EpMADS23, are most highly expressed in the stelidia, suggesting EpMADS22 may be required for fertile stamens. Conclusions: The median sepal, callus and stelidia of E. pusilla appear to be derived from a sepal, a stamen that gained petal identity, and stamens, respectively. Duplications, diversifying selection and changes in spatial expression of different MADS-box genes shaped these organs, enabling the rewardless flowers of E. pusilla to mimic an unrelated rewarding flower for pollinator attraction. These genetic changes are not incorporated in current models and urge for a rethinking of the evolution of deceptive flowers.
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| 12. |
- HUNER, NPA, et al.
(författare)
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PHOTOSYNTHESIS, PHOTOINHIBITION AND LOW-TEMPERATURE ACCLIMATION IN COLD TOLERANT PLANTS
- 1993
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Ingår i: Photosynthesis Research. - 0166-8595 .- 1573-5079. ; 37:1, s. 19-39
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Tidskriftsartikel (refereegranskat)abstract
- Cold acclimation requires adjustment to a combination of light and low temperature, conditions which are potentially photoinhibitory. The photosynthetic response of plants to low temperature is dependent upon time of exposure and the developmental history of the leaves. Exposure of fully expanded leaves of winter cereals to short-term, low temperature shifts inhibits whereas low temperature growth stimulates electron transport capacity and carbon assimilation. However, the photosynthetic response to low temperature is clearly species and cultivar dependent. Winter annuals and algae which actively grow and develop at low temperature and moderate irradiance acquire a resistance to irradiance 5- to 6-fold higher than their growth irradiance. Resistance to short-term photoinhibition (hours) in winter cereals is a reflection of the increased capacity to keep Q(A) oxidized under high light conditions and low temperature. This is due to an increased capacity for photosynthesis. These characteristics reflect photosynthetic acclimation to low growth temperature and can be used to predict the freezing tolerance of cereals. It is proposed that the enhanced photosynthetic capacity reflects an increased flux of fixed carbon through to sucrose in source tissue as a consequence of the combined effects of increased storage of carbohydrate as fructans in the vacuole of leaf mesophyll cells and an enhanced export to the crown due to its increased sink activity. Long-term exposure (months) of cereals to low temperature photoinhibition indicates that this reduction of photochemical efficiency of PS II represents a stable, long-term down regulation of PS II to match the energy requirements for CO2 fixation. Thus, photoinhibition in vivo should be viewed as the capacity of plants to adjust photosynthetically to the prevailing environmental conditions rather than a process which necessarily results in damage or injury to plants. Not all cold tolerant, herbaceous annuals use the same mechanism to acquire resistance to photoinhibition. In contrast to annuals and algae, overwintering evergreens become dormant during the cold hardening period and generally remain susceptible to photoinhibition. It is concluded that the photosynthetic response to low temperatures and susceptibility to photoinhibition are consequences of the overwintering strategy of the plant species.
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| 13. |
- Hurry, V.M., et al.
(författare)
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Effects of growth at cold hardening temperatures and temperature shifts on resistance to photoinhibition
- 1993
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Ingår i: Advances in plant cold hardiness. - Boca Raton : CRC Press. - 9781351069526 - 0849349508 ; , s. 103-112
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Bokkapitel (refereegranskat)abstract
- This chapter presents a summary of results that illustrate the photosynthetic responses of cold-tolerant cereals, spinach, and pine to low temperature-induced photoinhibition. Pre Exposure to a low temperature regime induces a cold-hardened state that imparts a certain level of freezing resistance and enhances the winter survival of the seedlings under natural conditions. Photosynthesis provides the energy for this cold hardening process. The phenomenon of resistance to photoinhibition was examined at several levels of cellular organization in winter rye: isolated thylakoids; isolated, intact mesophyll cells; and leaf segments. In contrast to the herbaceous cold-tolerant plants, Scots pine exposed to cold hardening conditions exhibited the same susceptibility to low temperature-induced photoinhibition as nonhardened Scots pine. To attain maximum cold hardiness, the herbaceous plants grow and develop at low temperatures and, as a consequence, develop a resistance to low temperature photoinhibition. The capacity to down-regulate PSII through photoinhibition may be an important characteristic that separates cold-tolerant from chilling-sensitive plant species.
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| 14. |
- Morgan-Kiss, R M, et al.
(författare)
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The Antarctic psychrophile, Chlamydomonas raudensis Ettl (UWO241) (Chlorophyceae, Chlorophyta), exhibits a limited capacity to photoacclimate to red light
- 2005
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Ingår i: Journal of Phycology. - : Wiley. - 0022-3646 .- 1529-8817. ; 41:4, s. 791-800
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Tidskriftsartikel (refereegranskat)abstract
- The psychrophilic Antarctic alga, Chlamydomonas raudensis Ettl (UWO241), grows under an extreme environment of low temperature and low irradiance of a limited spectral quality (blue-green). We investigated the ability of C. raudensis to acclimate to long-term imbalances in excitation caused by light quality through adjustments in photosystem stoichiometry. Log-phase cultures of C. raudensis and C. reinhardtii grown under white light were shifted to either blue or red light for 12 h. Previously, we reported that C. raudensis lacks the ability to redistribute light energy via the short-term mechanism of state transitions. However, similar to the model of mesophilic alga, C. reinhardtii, the psychrophile retained the capacity for long-term adjustment in energy distribution between PSI and PSII by modulating the levels of PSI reaction center polypeptides, PsaA/PsaB, with minimal changes in the content of the PSII polypeptide, D1, in response to changes in light quality. The functional consequences of the modulation in PSI/PSII stoichiometry in the psychrophile were distinct from those observed in C. reinhardtii. Exposure of C. raudensis to red light caused 1) an inhibition of growth and photosynthetic rates, 2) an increased reduction state of the intersystem plastoquinone pool with concomitant increases in nonphotochemical quenching, 3) an uncoupling of the major light-harvesting complex from the PSII core, and 4) differential thylakoid protein phosphorylation profiles compared with C. reinhardtii. We conclude that the characteristic low levels of PSI relative to PSII set the limit in the capacity of C. raudensis to photoacclimate to an environment enriched in red light.
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| 15. |
- Segev, Gideon, et al.
(författare)
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The 2022 solar fuels roadmap
- 2022
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Ingår i: Journal of Physics D. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 55:32
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Tidskriftsartikel (refereegranskat)abstract
- Renewable fuel generation is essential for a low carbon footprint economy. Thus, over the last five decades, a significant effort has been dedicated towards increasing the performance of solar fuels generating devices. Specifically, the solar to hydrogen efficiency of photoelectrochemical cells has progressed steadily towards its fundamental limit, and the faradaic efficiency towards valuable products in CO2 reduction systems has increased dramatically. However, there are still numerous scientific and engineering challenges that must be overcame in order to turn solar fuels into a viable technology. At the electrode and device level, the conversion efficiency, stability and products selectivity must be increased significantly. Meanwhile, these performance metrics must be maintained when scaling up devices and systems while maintaining an acceptable cost and carbon footprint. This roadmap surveys different aspects of this endeavor: system benchmarking, device scaling, various approaches for photoelectrodes design, materials discovery, and catalysis. Each of the sections in the roadmap focuses on a single topic, discussing the state of the art, the key challenges and advancements required to meet them. The roadmap can be used as a guide for researchers and funding agencies highlighting the most pressing needs of the field.
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| 16. |
- Stachura, A, et al.
(författare)
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Transfusion of intra-operative autologous whole blood: influence on complement activation and interleukin formation.
- 2011
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Ingår i: Vox sanguinis. - : Wiley. - 1423-0410 .- 0042-9007. ; 100:2, s. 239-46
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Tidskriftsartikel (refereegranskat)abstract
- Transfusion of autologous whole blood is one available method to reduce the need for allogenic blood transfusion. The objective of this study was to investigate the safety of transfusion of intra-operative autologous whole blood by monitoring plasma concentration of laboratory variables and adverse events after transfusion with the Sangvia(®) system.
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| 17. |
- Vautard, R., et al.
(författare)
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Skill and uncertainty of a regional air quality model ensemble
- 2009
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 43:31, s. 4822-4832
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Tidskriftsartikel (refereegranskat)abstract
- Recently several regional air quality projects were carried out to support the negotiation under the Clean Air For Europe (CAFE) programme by predicting the impact of emission control policies with an ensemble of models. Within these projects, CITYDELTA and EURODELTA, the fate of air quality at the scale of European cities or that of the European continent was studied using several models. In this article we focus on the results of EURODELTA. The predictive skill of the ensemble of models is described for ozone, nitrogen dioxide and secondary inorganic compounds, and the uncertainty in air quality modelling is examined through the model ensemble spread of concentrations. For ozone daily maxima the ensemble spread origin differs from one region to another. In the neighbourhood of cities or in mountainous areas the spread of predicted values does not span the range of observed data, due to poorly resolved emissions or complex-terrain meteorology. By contrast in Atlantic and North Sea coastal areas the spread of predicted values is found to be larger than the observations. This is attributed to large differences in the boundary conditions used in the different models. For NO2 daily averages the ensemble spread is generally too small compared with observations. This is because models miss highest values occurring in stagnant meteorology in stable boundary layers near cities. For secondary particulate matter compounds the simulated concentration spread is more balanced, observations falling nearly equiprobably within the ensemble, and the spread originates both from meteorology and aerosol chemistry and thermodynamics. © 2008.
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| 18. |
- HURRY, VM, 1960-, et al.
(författare)
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EFFECT OF LONG-TERM PHOTOINHIBITION ON GROWTH AND PHOTOSYNTHESIS OF COLD-HARDENED SPRING AND WINTER-WHEAT
- 1992
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Ingår i: Planta. - 0032-0935 .- 1432-2048. ; 188:3, s. 369-375
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Tidskriftsartikel (refereegranskat)abstract
- The effect of repeated exposure to high light (1200 mumol . m-2 . s-1 photosynthetic photon flux density, PPFD) at 5-degrees-C was examined in attached leaves of cold-grown spring (cv. Katepwa) and winter (cv. Kharkov) wheat (Triticum aestivum L.) over an eight-week period. Under these conditions, Kharkov winter wheat exhibited a daily reduction of 24% in F(V)/F(M) (the ratio of variable to maximal fluorescence in the dark-adapted state), in contrast to 41% for cold-grown Katepwa spring wheat. Both cultivars were able to recover from this daily suppression of F(V)/F(M) such that the leaves exhibited an average morning F(V)/F(M) of 0.651 +/- 0.004. Fluorescence measurements made under steady-state conditions as a function of irradiance from 60 to 2000 mumol . m-2 . s-1 indicated that the yield of photosystem II (PSII) electron transport under light-saturating conditions was the same for photoinhibited and control cold-grown plants, regardless of cultivar. Repeated daily exposure to high light at low temperature did not increase resistance to short-term photoinhibition, although zeaxanthin levels increased by three- to fourfold. In addition, both cultivars increased the rate of dry-matter accumulation, relative to control plants maintained at 5-degrees-C and 250 mumol . m-2 . s-1 PPFD (10% and 28% for Katepwa and Kharkov, respectively), despite exhibiting suppressed F(V)/F(M) and reduced photon yields for O2 evolution following daily high-light treatments. Thus, although photosynthetic efficiency is suppressed by a long-term, photoinhibitory treatment, light-saturated rates of photosynthesis are sufficiently high during the high-light treatment to offset any reduction in photochemical efficiency of PSII. We suggest that in these cold-tolerant plants, photoinhibition of PSII may represent a long-term, stable, down-regulation of photochemistry to match the overall photosynthetic demand for ATP and reducing equivalents.
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| 19. |
- Ivanov, A G, et al.
(författare)
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Low-temperature modulation of the redox properties of the acceptor side of photosystem II : photoprotection through reaction centre quenching of excess energy
- 2003
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Ingår i: Physiologia Plantarum. - 0031-9317 .- 1399-3054. ; 119:3, s. 376-383
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Tidskriftsartikel (refereegranskat)abstract
- Although it has been well established that acclimation to low growth temperatures is strongly correlated with an increased proportion of reduced Q(A) in all photosynthetic groups, the precise mechanism controlling the redox state of Q(A) and its physiological significance in developing cold tolerance in photoautotrophs has not been fully elucidated. Our recent thermoluminescence (TL) measurements of the acceptor site of PSII have revealed that short-term exposure of the cyanobacterium Synechococcus sp. PCC 7942 to cold stress, overwintering of Scots pine (Pinus sylvestris L.), and acclimation of Arabidopsis plants to low growth temperatures, all caused a substantial shift in the characteristic T-M of S(2)Q(B)(-) recombination to lower temperatures. These changes were accompanied by much lower overall TL emission, restricted electron transfer between Q(A) and Q(B), and in Arabidopsis by a shift of the S(2)Q(A)(-)-related peak to higher temperatures. The shifts in recombination temperatures are indicative of a lower activation energy for the S(2)Q(B)(-) redox pair and a higher activation energy for the S(2)Q(A)(-) redox pair. This results in an increase in the free-energy gap between P680(+)Q(A)(-) and P680(+)Pheo(-) and a narrowing of the free energy gap between Q(A) and Q(B) electron acceptors. We propose that these effects result in an increased population of reduced Q(A) (Q(A)(-)), facilitating non-radiative P680(+)Q(A)(-) radical pair recombination within the PSII reaction centre. The proposed reaction centre quenching could be an important protective mechanism in cyanobacteria in which antenna and zeaxanthin cycle-dependent quenching are not present. In herbaceous plants, the enhanced capacity for dissipation of excess light energy via PSII reaction centre quenching following cold acclimation may complement their capacity for increased utilization of absorbed light through CO2 assimilation and carbon metabolism. During overwintering of evergreens, when photosynthesis is inhibited, PSII reaction centre quenching may complement non-photochemical quenching within the light-harvesting antenna when zeaxanthin cycle-dependent energy quenching is thermodynamically restricted by low temperatures. We suggest that PSII reaction centre quenching is a significant mechanism enabling cold-acclimated organisms to acquire increased resistance to high light.
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| 20. |
- Ivanov, Alexander G., et al.
(författare)
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The decreased PG content of pgp1 inhibits PSI photochemistry and limits reaction center and light-harvesting polypeptide accumulation in response to cold acclimation
- 2022
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Ingår i: Planta. - : Springer. - 0032-0935 .- 1432-2048. ; 255:2
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Tidskriftsartikel (refereegranskat)abstract
- Main conclusion: Decreased PG constrains PSI activity due to inhibition of transcript and polypeptide abundance of light-harvesting and reaction center polypeptides generating a reversible, yellow phenotype during cold acclimation of pgp1.Cold acclimation of the Arabidopsis pgp1 mutant at 5 °C resulted in a pale-yellow phenotype with abnormal chloroplast ultrastructure compared to its green phenotype upon growth at 20 °C despite a normal cold-acclimation response at the transcript level. In contrast, wild type maintained its normal green phenotype and chloroplast ultrastructure irrespective of growth temperature. In contrast to cold acclimation of WT, growth of pgp1 at 5 °C limited the accumulation of Lhcbs and Lhcas assessed by immunoblotting. However, a novel 43 kD polypeptide of Lhcb1 as well as a 29 kD polypeptide of Lhcb3 accumulated in the soluble fraction which was absent in the thylakoid membrane fraction of cold-acclimated pgp1 which was not observed in WT. Cold acclimation of pgp1 destabilized the Chl–protein complexes associated with PSI and predisposed energy distribution in favor of PSII rather than PSI compared to the WT. Functionally, in vivo PSI versus PSII photochemistry was inhibited in cold-acclimated pgp1 to a greater extent than in WT relative to controls. Greening of the pale-yellow pgp1 was induced when cold-acclimated pgp1 was shifted from 5 to 20 °C which resulted in a marked decrease in excitation pressure to a level comparable to WT. Concomitantly, Lhcbs and Lhcas accumulated with a simultaneous decrease in the novel 43 and 29kD polypeptides. We conclude that the reduced levels of phosphatidyldiacylglycerol in the pgp1 limit the capacity of the mutant to maintain the structure and function of its photosynthetic apparatus during cold acclimation. Thus, maintenance of normal thylakoid phosphatidyldiacylglycerol levels is essential to stabilize the photosynthetic apparatus during cold acclimation.
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| 21. |
- Kocur, Chris, et al.
(författare)
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Characterization of nZVI mobility in a field scale test
- 2014
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 48:5, s. 2862-2869
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Tidskriftsartikel (refereegranskat)abstract
- Nanoscale zero valent iron (nZVI) particles were injected into a contaminated sandy subsurface area in Sarnia, Ontario. The nZVI was synthesized on site, creating a slurry of 1 g/L nanoparticles using the chemical precipitation method with sodium borohydride (NaBH4) as the reductant in the presence of 0.8% wt. sodium carboxymethylcellulose (CMC) polymer to form a stable suspension. Individual nZVI particles formed during synthesis had a transmission electron microscopy (TEM) quantified particle size of 86.0 nm and dynamic light scattering (DLS) quantified hydrodynamic diameter for the CMC and nZVI of 624.8 nm. The nZVI was delivered to the subsurface via gravity injection. Peak normalized total Fe breakthrough of 71% was observed 1m from the injection well and remained above 50% for the 24 hour injection period. Samples collected from a monitoring well 1 m from the injection contained nanoparticles with TEM-measured particle diameter of 80.2 nm and hydrodynamic diameter of 562.9 nm. No morphological changes were discernible between the injected nanoparticles and nanoparticles recovered from the monitoring well. Energy dispersive X-ray spectroscopy (EDS) was used to confirm the elemental composition of the iron nanoparticles sampled from the downstream monitoring well, verifying the successful transport of nZVI particles. This study suggests that CMC stabilized nZVI can be transported at least 1 m to the contaminated source zone at significant Fe0 concentrations for reaction with target contaminants.
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| 22. |
- KROL, M, et al.
(författare)
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CHLOROPHYLL A/B-BINDING PROTEINS, PIGMENT CONVERSIONS, AND EARLY LIGHT-INDUCED PROTEINS IN A CHLOROPHYLL B-LESS BARLEY MUTANT
- 1995
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Ingår i: Plant Physiology. - 0032-0889 .- 1532-2548. ; 107:3, s. 873-883
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Tidskriftsartikel (refereegranskat)abstract
- Monospecific polyclonal antibodies have been raised against synthetic peptides derived from the primary sequences from different plant light-harvesting Chl a/b-binding (LHC) proteins. Together with other monospecific antibodies, these were used to quantify the levels of the 10 different LHC proteins in wild-type and chlorina 12 barley (Hordeum vulgare L.), grown under normal and intermittent light (ImL). Chlorina 12, grown under normal light, lacked Lhcb1 (type I LHC II) and Lhcb6 (CP24) and had reduced amounts of Lhcb2, Lhcb3 (types II and III LHC II), and Lhcb4 (CP 29). Chlorina f2 grown under ImL lacked all LHC proteins, whereas wild-type ImL plants contained Lhcb5 (CP 26) and a small amount of Lhcb2. The chlorina f2 ImL thylakoids were organized in large parallel arrays, but wild-type ImL thylakoids had appressed regions, indicating a possible role for Lhcb5 in grana stacking. Chlorina f2 grown under ImL contained considerable amounts of violaxanthin (2-3/reaction center), representing a pool of phototransformable xanthophyll cycle pigments not associated with LHC proteins. Chlorina f2 and the plants grown under ImL also contained early light-induced proteins (ELIPs) as monitored by western blotting. The levels of both ELIPs and xanthophyll cycle pigments increased during a 1 h of high light treatment, without accumulation of LHC proteins. These data are consistent with the hypothesis that ELIPs are pigment-binding proteins, and we suggest that ELIPs bind photoconvertible xanthophylls and replace ''normal'' LHC proteins under conditions of light stress.
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| 23. |
- Krol, M, et al.
(författare)
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Greening under high light or cold temperature affects the level of xanthophyll-cycle pigments, early light-inducible proteins, and light-harvesting polypeptides in wild-type barley and the chlorina f2 mutant
- 1999
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Ingår i: Plant Physiology. - 0032-0889 .- 1532-2548. ; 120:1, s. 193-203
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Tidskriftsartikel (refereegranskat)abstract
- Etiolated seedlings of wild type and the chlorina f2 mutant of barley (Hordeum vulgare) were exposed to greening at either 5 degrees C or 20 degrees C and continuous illumination varying from 50 to 800 mu mol m(-2) s(-1). Exposure to either moderate temperature and high light or low temperature and moderate light inhibited chlorophyll a and b accumulation in the wild type and in the f2 mutant. Continuous illumination under these greening conditions resulted in transient accumulations of zeaxanthin, concomitant transient decreases in violaxanthin, and fluctuations in the epoxidation state of the xanthophyll pool, Photoinhibition-induced xanthophyll-cycle activity was detectable after only 3 h of greening at 20 degrees C and 250 mu mol m(-2) s(-1). Immunoblot analyses of the accumulation of the 14-kD early light-inducible protein but not the major (Lhcb2) or minor (Lhcb5) light-harvesting polypeptides demonstrated transient kinetics similar to those observed for zeaxanthin accumulation during greening at either 5 degrees C or 20 degrees C for both the wild type and the f2 mutant. Furthermore, greening of the f2 mutant at either 5 degrees C or 20 degrees C indicated that Lhcb2 is not essential for the regulation of the xanthophyll cycle in barley. These results are consistent with the thesis that early light-inducible proteins may bind zeaxanthin as well as other xanthophylls and dissipate excess light energy to protect the developing photosynthetic apparatus from excess excitation. We discuss the role of energy balance and photosystem II excitation pressure in the regulation of the xanthophyll cycle during chloroplast biogenesis in wild-type barley and the f2 mutant.
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| 24. |
- Krol, M, et al.
(författare)
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Low growth temperature inhibition of photosynthesis in cotyledons of jack pine seedlings (Pinus banksiana) is due to impaired chloroplast development
- 2002
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Ingår i: Canadian Journal of Botany. - 0008-4026 .- 1480-3305. ; 80:10, s. 1042-1051
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Tidskriftsartikel (refereegranskat)abstract
- Cotyledons of jack pine seedlings (Pinus banksiana Lamb.) grown from seeds were expanded at low temperature (5degreesC), and total Chl content per unit area of cotyledons in these seedlings was only 57% of that observed for cotyledons on 20degreesC-grown controls. Chl a/b ratio of 5degreesC-grown jack pine was about 20% lower (2.3 +/- 0.1) than 20degreesC controls (2.8 +/- 0.3). Separation of Chl-protein complexes and SDS-PAGE indicated a significant reduction in the major Chl a containing complex of PSI (CP1) and PSII (CPa) relative to LHCII1 in 5degreesC compared to 20degreesC-grown seedlings. In addition, LHCII1/LHCII3 ratio increased from 3.8 in control (20degreesC) to 5.5 in 5degreesC-grown cotyledons. Ultrastructurally, 5degreesC-grown cotyledons had chloroplasts with swollen thylakoids as well as etiochloroplasts with distinct prolamellar bodies. Based on CO2-saturated O-2 evolution and in vivo Chl a fluorescence, cotyledons of 5degreesC jack pine exhibited an apparent photosynthetic efficiency that was 40% lower than 20degreesC controls. Seedlings grown at 5degreesC were photoinhibited more rapidly at 5degreesC and 1200 mumol.m(-2).s(-1) than controls grown at 20degreesC, although the final extent of photoinhibition was similar. Exposure to high light at 5degreesC stimulated the xanthophyll cycle in cotyledons of both controls and 5degreesC-grown seedlings. In contrast to winter cereals, we conclude that growth of jack pine at 5degreesC impairs normal chloroplast biogenesis, which leads to an inhibition of photosynthetic efficiency.
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| 25. |
- KROL, M, et al.
(författare)
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LOW-TEMPERATURE STRESS AND PHOTOPERIOD AFFECT AN INCREASED TOLERANCE TO PHOTOINHIBITION IN PINUS-BANKSIANA SEEDLINGS
- 1995
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Ingår i: Canadian Journal of Botany. - 0008-4026 .- 1480-3305. ; 73:8, s. 1119-1127
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Tidskriftsartikel (refereegranskat)abstract
- The capacity to develop tolerance to photoinhibition of photosynthesis was assessed in jack pine seedlings (Pinus banksiana Lamb.). Photoinhibition induced at 5 degrees C in control jack pine seedlings grown at 20 degrees C was saturated above an irradiance of 1000 mu mol . m(-2). s(-1) but was detectable at an irradiance as low as 25 mu mol . m(-2). s(-1). However, 20 degrees C seedlings shifted to 5 degrees C were 2-fold more tolerant to photoinhibition than 20 degrees C unshifted control seedlings, as detected by either the light-dependent decrease in photochemical efficiency or the apparent quantum yield of O-2 evolution. The extent of this tolerance of photoinhibition was dependent upon time, photoperiod, and irradiance during exposure to the low-temperature shift. Furthermore, the tolerance of photoinhibition was correlated with anthocyanin accumulation in 20 degrees C grown seedlings shifted to 5 degrees C. In addition, seedlings shifted to 5 degrees C and an 8-h photoperiod exhibited a 2-fold higher yield of photosystem II electron transport, which was associated with an increased capacity to keep Q(A), the first stable quinone electron acceptor of photosystem II, oxidized at high irradiance. This was consistent with a 2-fold higher rate of photosynthesis on a chlorophyll basis. We propose that the combination of light attenuation by anthocyanin in the epidermis and enhanced rates of photosynthesis may, in part, account for the reduced sensitivity of jack pine to photoinhibition at low temperature.
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