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- Andersson, Jenny, et al.
(author)
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Absence of the Lhcb1 and Lhcb2 proteins of the light-harvesting complex of photosystem II - effects on photosynthesis, grana stacking and fitness
- 2003
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In: The Plant Journal. - : Wiley. - 0960-7412 .- 1365-313X. ; 35:3, s. 350-361
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Journal article (peer-reviewed)abstract
- We have constructed Arabidopsis thaliana plants that are virtually devoid of the major light-harvesting complex, LHC II. This was accomplished by introducing the Lhcb2.1 coding region in the antisense orientation into the genome by Agrobacterium-mediated transformation. Lhcb1 and Lhcb2 were absent, while Lhcb3, a protein present in LHC II associated with photosystem (PS) II, was retained. Plants had a pale green appearance and showed reduced chlorophyll content and an elevated chlorophyll a/b ratio. The content of PS II reaction centres was unchanged on a leaf area basis, but there was evidence for increases in the relative levels of other light harvesting proteins, notably CP26, associated with PS II, and Lhca4, associated with PS I. Electron microscopy showed the presence of grana. Photosynthetic rates at saturating irradiance were the same in wild-type and antisense plants, but there was a 10-15% reduction in quantum yield that reflected the decrease in light absorption by the leaf. The antisense plants were not able to perform state transitions, and their capacity for non-photochemical quenching was reduced. There was no difference in growth between wild-type and antisense plants under controlled climate conditions, but the antisense plants performed worse compared to the wild type in the field, with decreases in seed production of up to 70%.
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- Gromov, Sergey P, et al.
(author)
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Synthesis, Structure, Spectroscopic Studies, and Complexation of Novel Crown Ether Butadienyl Dyes
- 2002
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In: Helvetica Chimica Acta. ; 85:1, s. 60-81
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Journal article (peer-reviewed)abstract
- Butadienyl dyes of the benzothiazole series with various fragments of benzocrown ethers 1a-c were synthesized for the first time. The structures and spectral properties of crown-containing butadienyl dyes and their complexes with alkali and alkaline-earth metal cations were studied by X-ray diffraction analysis and 1H-NMR, UV/VIS, and resonance Raman spectroscopy. To interpret the experimental results, quantum-chemical calculations were performed. In the case of Sr2+ and Ba2+ ions, the formation of strong sandwich complexes [M(1b)2]2+ of an unusual structure involving stacking interactions was established; the dye molecules are arranged one above another in the complex according to the head-to-head' pattern.
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- Moralejo, Daniel H, et al.
(author)
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Genetic dissection of lymphopenia from autoimmunity by introgression of mutated Ian5 gene onto the F344 rat.
- 2003
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In: Journal of Autoimmunity. - 0896-8411. ; 21:4, s. 315-324
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Journal article (peer-reviewed)abstract
- Peripheral T cell lymphopenia (lyp) in the BioBreeding (BB) rat is linked to a frameshift mutation in Ian5, a member of the Immune Associated Nucleotide (Ian) gene family on rat chromosome 4. This lymphopenia leads to type 1 (insulin-dependent) diabetes mellitus (T1DM) at rates up to 100% when combined with the BB rat MHC RT1 u/u genotype. In order, to better study the lymphopenia phenotype without possible confounding effects of diabetes or other autoimmune disease, we generated congenic F344.lyp rats by introgression of lyp on diabetes-resistant MHC RT1 lv1/lv1 F344 rats. Analysis of thymic CD4 and CD8 T lymphocytes revealed no difference in the percentage of CD4(-)CD8(+)and CD4(+)CD8(-)subsets in lyp/lyp compared to +/+ F344 rats. The same subsets was however dramatically reduced in blood (P=0.005), spleen (P=0.019) and mesenteric lymph nodes (MLN) (P<0.0001). Compared to F344 +/+ rats double positive CD4(+)CD8(+)T cells were increased only in lyp/lyp spleen (P=0.034) while double n
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- Westblad, C., et al.
(author)
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A study on toxic organic emissions from batch combustion of styrene
- 2002
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In: Chemosphere. - 0045-6535 .- 1879-1298. ; 49:4, s. 395-412
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Journal article (peer-reviewed)abstract
- Results from a laboratory-scale investigation on batch combustion of styrene are reported herein. Limited quantities of waste styrene monomer are incinerated, however this monomer is, also, the primary pyrolyzate during combustion of waste polystyrene, the second most abundant polymer produced worldwide. Thus, its combustion-generated emissions are of importance to the operation of hazardous waste incinerators and municipal waste-to-energy powerplants. This work focuses on emissions of polycyclic aromatic hydrocarbons (PAHs), particulates, as well as carbon monoxide. To investigate methods for minimizing such emissions, batch combustion of the monomer was conducted in a two-stage muffle furnace. An additional air mixing chamber was installed between the two stages. Small quantities of the liquid monomer were inserted in the primary furnace which served as a gasifier/burner. The furnace temperature was in the range of 300-1000 °C and diffusion flames were formed under most conditions. Upon mixing with additional air, combustion of unburned gaseous fuel and primary reaction products continued in the secondary furnace (afterburner), which was kept at a constant temperature of either 1000 or 800 °C. Using this technique, conditions that minimize emissions were explored and theoretical investigations on the fate of pollutants in the secondary furnace were undertaken. Results revealed that combustion of styrene, which is a highly volatile fuel, occurred with the formation of flames that were often non-anchored, unsteady and unstable. Emissions of organic pollutants, soot and CO were more intense than in the case of the polystyrene combustion, studied previously under identical conditions, due to the additional depolymerization/pyrolysis steps therein. The emissions from the secondary furnace exceeded those of the primary furnace, consistent with the fact that a very significant fraction of the fuel conversion occurred in the secondary chamber. Clear trends in the emissions of PAHs and soot, products of incomplete combustion, with the temperature of the primary furnace (gasifier) were observed. Emissions were drastically reduced with lowering the gasifier temperature. While final cumulative emissions of PAHs and soot accounted for more than one third of the mass of the fuel at high temperatures, their concentrations at the exit of the afterburner were negligible when the primary furnace was operated at 300 °C under pyrolytic conditions. In the latter case air was added to the afterburner. Numerical modeling based on a complex reaction network was used for the description of the primary furnace as well as of the afterburner. Kinetic analysis showed acetylene and benzene to be key species in the growth of PAHs. Formation of PAHs in the afterburner, found experimentally, was reproduced by the model using a plug-flow assumption. © 2002 Elsevier Science Ltd. All rights reserved.
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