| 1. |
- Andersson, Jenny, et al.
(författare)
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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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Ingår i: The Plant Journal. - : Wiley. - 0960-7412 .- 1365-313X. ; 35:3, s. 350-361
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Andersson, Jenny, et al.
(författare)
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Antisense inhibition of the photosynthetic antenna proteins CP29 and CP26 : implications for the mechanism of protective energy dissipation
- 2001
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Ingår i: The Plant Cell. - : American Society of Plant Biologists. - 1040-4651 .- 1532-298X. ; 13:5, s. 1193-1204
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Tidskriftsartikel (refereegranskat)abstract
- The specific roles of the chlorophyll a/b binding proteins CP29 and CP26 in light harvesting and energy dissipation within the photosynthetic apparatus have been investigated. Arabidopsis was transformed with antisense constructs against the genes encoding the CP29 or CP26 apoprotein, which gave rise to several transgenic lines with remarkably low amounts of the antisense target proteins. The decrease in the level of CP24 protein in the CP29 antisense lines indicates a physical interaction between these complexes. Analysis of chlorophyll fluorescence showed that removal of the proteins affected photosystem II function, probably as a result of changes in the organization of the light-harvesting antenna. However, whole plant measurements showed that overall photosynthetic rates were similar to those in the wild type. Both antisense lines were capable of the qE type of nonphotochemical fluorescence quenching, although there were minor changes in the capacity for quenching and in its induction kinetics. High-light-induced violaxanthin deepoxidation to zeaxanthin was not affected, although the pool size of these pigments was decreased slightly. We conclude that CP29 and CP26 are unlikely to be sites for nonphotochemical quenching.
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| 3. |
- Fäldt, Jenny, 1971, et al.
(författare)
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Reduced exercise endurance in interleukin-6-deficient mice
- 2004
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Ingår i: Endocrinology. - 0013-7227. ; 145:6, s. 2680-6
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Tidskriftsartikel (refereegranskat)abstract
- IL-6 is produced and released in large amounts from skeletal muscle during prolonged exercise in both mice and humans, but there are few data indicating the biological significance of this. IL-6 exerts metabolic effects such as stimulating energy expenditure and reducing body fat mass. We have now investigated the effects of IL-6 deficiency on exercise endurance and energy expenditure in preobese and obese IL-6-deficient (IL-6(-/-)) mice. Four-month-old preobese and 7-month-old obese IL-6(-/-) male mice backcrossed to C57BL/6 and their littermate controls were exercised on a treadmill, and energy expenditure was measured as oxygen consumption with the use of indirect calorimetry. The preobese IL-6(-/-) mice were significantly leaner than the control mice, whereas the older IL-6(-/-) mice, as expected, had developed obesity. Resting young, but not older, IL-6(-/-) mice had an elevated respiratory exchange ratio (RER), indicating that they oxidize carbohydrates rather than fat for energy utilization. During exercise, the young and older IL-6(-/-) mice had a reduced endurance and a progressive decrease in oxygen consumption compared with control mice. There was no difference in RER in young IL-6(-/-) mice, whereas RER was enhanced in older IL-6(-/-), mice during exercise. In summary, IL-6(-/-) mice have reduced endurance and energy expenditure during exercise, suggesting that IL-6 is necessary for normal exercise capacity.
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| 4. |
- Ganeteg, Ulrika, et al.
(författare)
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Is each light-harvesting complex protein important for plant fitness?
- 2004
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Ingår i: Plant Physiology. - Rockville, Md. : American Society of Plant Physiologists. - 0032-0889 .- 1532-2548. ; 134:1, s. 502-509
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Tidskriftsartikel (refereegranskat)abstract
- Many of the photosynthetic genes are conserved among all higher plants, indicating that there is strong selective pressure to maintain the genes of each protein. However, mutants of these genes often lack visible growth phenotypes, suggesting that they are important only under certain conditions or have overlapping functions. To assess the importance of specific genes encoding the light-harvesting complex (LHC) proteins for the survival of the plant in the natural environment, we have combined two different scientific traditions by using an ecological fitness assay on a set of genetically modified Arabidopsis plants with differing LHC protein contents. The fitness of all of the LHC-deficient plants was reduced in some of the growth environments, supporting the hypothesis that each of the genes has been conserved because they provide ecological flexibility, which is of great adaptive value given the highly variable conditions encountered in nature.
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| 5. |
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| 6. |
- Vikgren, Jenny, 1957, et al.
(författare)
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High-resolution computed tomography in healthy smokers and never-smokers: a 6-year follow-up study of men born in 1933
- 2004
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Ingår i: Acta Radiol. ; 45:1
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To elucidate whether emphysematous lesions and other high-resolution computed tomography (HRCT) findings considered associated with smoking are part of a progressive process, and to measure the extent to which similar changes are found in never-smokers. MATERIAL AND METHODS: Healthy smokers and never-smokers were recruited from a randomized epidemiological study and investigated with a 6-year interval. Emphysema, parenchymal and subpleural nodules, ground-glass opacities, bronchial alterations, and septal lines were evaluated in 66 subjects (40 smokers, 11 of whom had stopped smoking in the interval, and 26 never-smokers). Lung function was tested. RESULTS: All except emphysematous lesions were present to some extent in never-smokers. Emphysema, parenchymal nodules, and septal lines occurred significantly more in current smokers, and a progression in extent of emphysema, ground-glass opacities, bronchial alterations and septal lines was seen. There was no significant change among those who stopped and never-smokers except for bronchial alterations, which progressed in never-smokers. CONCLUSION: In healthy, elderly never-smokers a low extent of various HRCT findings has to be considered normal. Emphysema, parenchymal nodules, and ground-glass opacities are indicative of smoking-induced disease. Further progress may cease if smoking is stopped.
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| 7. |
- Vikgren, Jenny, 1957, et al.
(författare)
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Value of air trapping in detection of small airways disease in smokers
- 2003
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Ingår i: Acta Radiol. ; 44:5
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To test the hypothesis that diffuse and/or focal air trapping are sensitive indicators of airflow obstruction in smoker's small airways disease, when age, gender and presence of emphysematous lesions were allowed for. MATERIAL AND METHODS: Fifty-eight smokers and 34 never smokers, recruited from a randomized population study of men born in 1933, were investigated by HRCT and by extended pulmonary function tests, including a sensitive test for small airways disease (N2 slope). Diffuse air trapping was evaluated by calculating a quotient of mean lung density at expiration and inspiration. Focal air trapping was scored visually by consensus. RESULTS: Diffuse air trapping did not differ between non-emphysematous smokers and never smokers. Furthermore, diffuse air trapping correlated well to the quotient between the residual volume and total lung capacity (RV/TLC, p = 0.01) and was consequently higher in emphysematous smokers than in never smokers. Focal air trapping was found as frequently in smokers without emphysema as in never smokers. Smokers with emphysema showed significantly less focal air trapping. Neither the N2 slope nor any of the other lung function variables differed between those with and without focal air trapping among non-emphysematous smokers. CONCLUSION: Neither diffuse nor focal air trapping are sensitive indicators of smoker's small airways disease.
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| 8. |
- Yakushevska, A. E., et al.
(författare)
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The structure of photosystem II in Arabidopsis : localization of the CP26 and CP29 antenna complexes
- 2003
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 42:3, s. 608-613
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Tidskriftsartikel (refereegranskat)abstract
- A genetic approach has been adopted to investigate the organization of the light-harvesting proteins in the photosystem II (PSII) complex in plants. PSII membrane fragments were prepared from wild-type Arabidopis thaliana and plants expressing antisense constructs to Lhcb4 and Lhcb5 genes, lacking CP29 and CP26, respectively (Andersson et al. (2001) Plant Cell 13, 1193-1204). Ordered PSII arrays and PSII supercomplexes were isolated from the membranes of plants lacking CP26 but could not be prepared from those lacking CP29. Membranes and supercomplexes lacking CP26 were less stable than those prepared from the wild type. Transmission electron microscopy aided by single-particle image analysis was applied to the ordered arrays and the isolated PSII complexes. The difference between the images obtained from wild type and antisense plants showed the location of CP26 to be near CP43 and one of the light-harvesting complex trimers. Therefore, the location of the CP26 within PSII was directly established for the first time, and the location of the CP29 complex was determined by elimination. Alterations in the packing of the PSII complexes in the thylakoid membrane also resulted from the absence of CP26. The minor light-harvesting complexes each have a unique location and important roles in the stabilization of the oligomeric PSII structure.
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