| 1. |
- Sjögren, Marie, et al.
(författare)
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Leptin deficiency reverses high metabolic state and weight loss without affecting central pathology in the R6/2 mouse model of Huntington's disease
- 2019
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Ingår i: Neurobiology of Disease. - : Elsevier BV. - 0969-9961 .- 1095-953X. ; 132
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 Body weight has been shown to be a predictor of clinical progression in Huntington's disease (HD). Alongside widespread neuronal pathology, both HD patients and the R6/2 mouse model of HD exhibit weight loss and increased energy expenditure, providing a rationale for targeting whole-body energy metabolism in HD. Leptin-deficient mice display low energy expenditure and increased body weight. We therefore hypothesized that normalizing energy metabolism in R6/2 mice, utilizing leptin- deficiency, would lead to a slower disease progression in the R6/2 mouse. In this study, we show that R6/2 mice on a leptin-deficient genetic background display increased body weight and increased fat mass compared to R6/2 mice, as well as wild type littermates. The increased body weight was accompanied by low energy expenditure, illustrated by a reduction in respiratory exchange rate. Leptin-deficient R6/2 mice had large white adipocytes with white adipocyte gene expression characteristics, in contrast to white adipose tissue in R6/2 mice, where white adipose tissue showed signs of browning. Leptin-deficient R6/2 mice did not exhibit improved neuropathological measures. Our results indicate that lowering energy metabolism in HD, by increasing fat mass and reducing respiratory exchange rate, is not sufficient to affect neuropathology. Further studies targeting energy metabolism in HD are warranted.
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| 2. |
- Aidemark, Mari, et al.
(författare)
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Trichoderma viride cellulase induces resistance to the antibiotic pore-forming peptide alamethicin associated with changes in the plasma membrane lipid composition of tobacco BY-2 cells
- 2010
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Ingår i: Bmc Plant Biology. - : Springer Science and Business Media LLC. - 1471-2229. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Background: Alamethicin is a membrane-active peptide isolated from the beneficial root-colonising fungus Trichoderma viride. This peptide can insert into membranes to form voltage-dependent pores. We have previously shown that alamethicin efficiently permeabilises the plasma membrane, mitochondria and plastids of cultured plant cells. In the present investigation, tobacco cells (Nicotiana tabacum L. cv Bright Yellow-2) were pre-treated with elicitors of defence responses to study whether this would affect permeabilisation. Results: Oxygen consumption experiments showed that added cellulase, already upon a limited cell wall digestion, induced a cellular resistance to alamethicin permeabilisation. This effect could not be elicited by xylanase or bacterial elicitors such as flg22 or elf18. The induction of alamethicin resistance was independent of novel protein synthesis. Also, the permeabilisation was unaffected by the membrane-depolarising agent FCCP. As judged by lipid analyses, isolated plasma membranes from cellulase-pretreated tobacco cells contained less negatively charged phospholipids ( PS and PI), yet higher ratios of membrane lipid fatty acid to sterol and to protein, as compared to control membranes. Conclusion: We suggest that altered membrane lipid composition as induced by cellulase activity may render the cells resistant to alamethicin. This induced resistance could reflect a natural process where the plant cells alter their sensitivity to membrane pore-forming agents secreted by Trichoderma spp. to attack other microorganisms, and thus adding to the beneficial effect that Trichoderma has for plant root growth. Furthermore, our data extends previous reports on artificial membranes on the importance of lipid packing and charge for alamethicin permeabilisation to in vivo conditions.
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| 3. |
- Andersson, Mats X., 1977, et al.
(författare)
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A chloroplast-localized vesicular transport system: a bio-informatics approach
- 2004
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 5:40
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Tidskriftsartikel (refereegranskat)abstract
- Background: The thylakoid membrane of higher plant chloroplasts is made of membrane lipids synthesized in the chloroplast envelope. As the inner envelope membrane and the thylakoid are separated by the aqueous stroma, a system for transporting newly synthesized lipids from the inner envelope membrane to the thylakoid is required. Ultrastructural as well as biochemical studies have indicated that lipid transport inside the chloroplast could be mediated by a system similar in characteristics to vesicular trafficking in the cytosol. If indeed the chloroplast system is related to cytosolic vesicular trafficking systems, a certain degree of sequence conservation between components of the chloroplast and the cytosolic systems could be expected. We used the Arabidopsis thaliana genome and web-based subcellular localization prediction tools to search for chloroplast-localized homologues of cytosolic vesicular trafficking components. Results: Out of the 28952 hypothetical proteins in the A. thaliana genome sequence, 1947 were predicted to be chloroplast-localized by two different subcellular localization predictors. In this chloroplast protein dataset, strong homologues for the main coat proteins of COPII coated cytosolic vesicles were found. Homologues of the small GTPases ARF1 and Sar1 were also found in the chloroplast protein dataset. Conclusion: Our database search approach gives further support to that a system similar to cytosolic vesicular trafficking is operational inside the chloroplast. However, solid biochemical data is needed to support the chloroplast localization of the identified proteins as well as their involvment in intra-chloroplast lipid trafficking.
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| 4. |
- Andersson, Mats X., 1977, et al.
(författare)
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Chloroplast biogenesis. Regulation of lipid transport to the thylakoid in chloroplasts isolated from expanding and fully expanded leaves of pea.
- 2001
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Ingår i: Plant physiology. - 0032-0889. ; 127:1, s. 184-93
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Tidskriftsartikel (refereegranskat)abstract
- To study the regulation of lipid transport from the chloroplast envelope to the thylakoid, intact chloroplasts, isolated from fully expanded or still-expanding pea (Pisum sativum) leaves, were incubated with radiolabeled lipid precursors and thylakoid membranes subsequently were isolated. Incubation with UDP[(3)H]Gal labeled monogalactosyldiacylglycerol in both envelope membranes and digalactosyldiacylglycerol in the outer chloroplast envelope. Galactolipid synthesis increased with incubation temperature. Transport to the thylakoid was slow below 12 degrees C, and exhibited a temperature dependency closely resembling that for the previously reported appearance and disappearance of vesicles in the stroma (D.J. Morré, G. Selldén, C. Sundqvist, A.S. Sandelius [1991] Plant Physiol 97: 1558-1564). In mature chloroplasts, monogalactosyldiacylglycerol transport to the thylakoid was up to three times higher than digalactosyldiacylglycerol transport, whereas the difference was markedly lower in developing chloroplasts. Incubation of chloroplasts with [(14)C]acyl-coenzyme A labeled phosphatidylcholine (PC) and free fatty acids in the inner envelope membrane and phosphatidylglycerol at the chloroplast surface. PC and phosphatidylglycerol were preferentially transported to the thylakoid. Analysis of lipid composition revealed that the thylakoid contained approximately 20% of the chloroplast PC. Our results demonstrate that lipids synthesized at the chloroplast surface as well as in the inner envelope membrane are transported to the thylakoid and that lipid sorting is involved in the process. Furthermore, the results also indicate that more than one pathway exists for galactolipid transfer from the chloroplast envelope to the thylakoid.
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| 5. |
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| 6. |
- Andersson, Mats X., 1977, et al.
(författare)
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Optical manipulation reveals strong attracting forces at membrane contact sites between endoplasmic reticulum and chloroplasts
- 2007
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Ingår i: Journal of Biological Chemistry. - 0021-9258. ; 282:2, s. 1170-1174
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Tidskriftsartikel (refereegranskat)abstract
- Eukaryote cells depend on membrane lipid trafficking from biogenic membranes, like the endoplasmic reticulum (ER), to other membranes in the cell. Two major routes for membrane lipid transport are recognized: vesicular trafficking and lipid transfer at zones of close contact between membranes. Specific ER regions involved in such membrane contact sites (MCSs) have been isolated, and lipid transfer at MCSs as well as protein-protein interactions between the partaking membranes have been demonstrated (reviewed by Holthuis, J. C. M., and Levine, T. P. (2005) Nat. Rev. 6, 209–220). Here we present the first demonstration of the physical association between membranes involved in MCSs: by using optical imaging and manipulation, strong attracting forces between ER and chloroplasts are revealed. We used Arabidopsis thaliana expressing green fluorescent protein in the ER lumen and observed leaf protoplasts by confocal microscopy. The ER network was evident, with ER branch end points apparently localized at chloroplast surfaces. After rupture of a protoplast using a laser scalpel, the cell content was released. ER fragments remained attached to the released chloroplasts and could be stretched out by optical tweezers. The applied force, 400 pN, could not drag a chloroplast free from its attached ER, which could reflect protein-protein interactions at the ER-chloroplast MCSs. As chloroplasts rely on import of ER-synthesized lipids, we propose that lipid transfer occurs at these MCSs. We suggest that lipid transfer at the MCSs also occurs in the opposite direction, for example to channel plastid-synthesized acyl groups to supply substrates for ER-localized synthesis of membrane and storage lipids.
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| 7. |
- Andersson, Mats X., 1977, et al.
(författare)
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Phosphate-deficient oat replaces a major portion of the plasma membrane phospholipids with the galactolipid digalactosyldiacylglycerol.
- 2003
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Ingår i: FEBS letters. - 0014-5793. ; 537:1-3, s. 128-32
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Tidskriftsartikel (refereegranskat)abstract
- The plasma membranes of oat normally resemble those of other eukaryotes in containing mainly phospholipids and sterols. We here report the novel finding that the galactolipid digalactosyldiacylglycerol (DGDG) can constitute a substantial proportion of oat plasma membrane lipids, in both shoots and roots. When oat was cultivated under severe phosphate limitation, up to 70% of the plasma membrane phosphoglycerolipids were replaced by DGDG. Our finding not only reflects a far more developed potential for plasticity in plasma membrane lipid composition than often assumed, but also merits interest in the context of the limited phosphate availability in many soils.
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| 8. |
- Andersson, Mats X., 1977, et al.
(författare)
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The involvement of cytosolic lipases in converting phosphatidyl choline to substrate for galactolipid synthesis in the chloroplast envelope :
- 2004
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Ingår i: Biochimica et Biophysica Acta-Molecular and Cell Biology of Lipids. - : Elsevier BV. - 1388-1981. ; 1684:1-3, s. 46-53
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Tidskriftsartikel (refereegranskat)abstract
- Here we report that cytosolic phospholipases are involved in the utilization of phosphatidylcholine (PC) as substrate for chloroplast-localized synthesis of monogalactosyldiacylglycerol (MGDG). Isolated chloroplasts were pre-incubated with lysoPC and [C-14]18:0-CoA to form [C-14]PC. When soluble plant proteins (cytosol) and UDP-galactose were added, [C-14] MGDG was formed. An inhibitor of phospholipase D markedly lowered the formation of [C-14]MGDG, whereas thermolysin pretreatment of the chloroplasts was without effect. The cytosolic activity resided in the >100-kDa fraction. In a second approach, [C-14]PC-containing lipid mixtures were incubated with cytosol. Degradation of [C-14]PC to [C-14]diacylglycerol was highest when the lipid composition of the mixture mimicked that of the outer chloroplast envelope. We also investigated whether PC of extraplastidic origin could function as substrate for MGDG synthesis. Isolated chloroplasts were incubated with enriched endoplasmic reticulum containing radiolabelled acyl lipids. In the presence of cytosol and UDPgalactose, there was a time-dependent transfer of [C-14]PC from this fraction to chloroplasts, where [C-14]MGDG was formed. We conclude that chloroplasts recruit cytosolic phospholipase D and phosphatidic acid phosphatase to convert PC to diacylglycerol. Apparently, these lipases do not interact with chloroplast surface proteins, but rather with outer membrane lipids, either for association to the envelope or for substrate presentation. (C) 2004 Elsevier B.V. All rights reserved.
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| 9. |
- Andersson, Mats X., 1977, et al.
(författare)
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The plasma membrane and the tonoplast as major targets for phospholipid- to-glycolipid replacement and stimulation of phospholipases in the plasma membrane
- 2005
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Ingår i: Journal of Biological Chemistry. ; 280:30, s. 27578-27586
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Tidskriftsartikel (refereegranskat)abstract
- We recently reported that cultivation of oat (Avena sativa L.) without phosphate resulted in plasma membrane phosphoglycerolipids being replaced to a large extent by digalactosyldiacylglycerol (DGDG) (Andersson, M. X., Stridh, M. H., Larsson, K. E., Liljenberg, C., and Sandelius, A. S. ( 2003) FEBS Lett. 537, 128-132). We report here that DGDG is not the only non-phosphorous-containing lipid that replaces phospholipids but that also the content of glucosylceramides and sterolglycosides increased in plasma membranes as a response to phosphate starvation. In addition, phosphate deficiency induced similar changes in lipid composition in the tonoplast. The phospholipid-to-glycolipid replacement apparently did not occur to any greater extent in endoplasmic reticulum, Golgi apparatus, or mitochondrial inner membranes. In contrast to the marked effects on lipid composition, the polypeptide patterns were largely similar between root plasma membranes from well-fertilized and phosphate-limited oat, although the latter condition induced at least four polypeptides, including a chaperone of the HSP80 or HSP90 family, a phosphate transporter, and a bacterial-type phosphoesterase. The latter polypeptide reacted with an antibody raised against a phosphate deficiency-induced phospholipase C from Arabidopsis thaliana (Nakamura, Y., Awai, K., Masuda, T., Yoshioka, Y., Takamiya, K., and Ohta, H. ( 2005) J. Biol. Chem. 280, 7469-7476). In plasma membranes from oat, however, a phospholipase D-type activity and a phosphatidic acid phosphatase were the dominant lipase activities induced by phosphate deficiency. Our results reflect a highly developed plasticity in the lipid composition of the plasma membrane and the tonoplast. In addition, phosphate deficiency-induced alterations in plasma membrane lipid composition may involve different sets of lipid-metabolizing enzymes in different plant tissues or species, at different stages of plant development and/or at different stages of stress adjustments.
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| 10. |
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| 11. |
- Kjellberg, J. Magnus, 1972, et al.
(författare)
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Acyl-CoA dependent acylation of phospholipids in the chloroplast envelope.
- 2000
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Ingår i: Biochimica et biophysica acta. - 0006-3002. ; 1485:2-3, s. 100-10
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Tidskriftsartikel (refereegranskat)abstract
- Acyl-CoAs are substrates for acyl lipid synthesis in the endoplasmic reticulum. In addition, they may also be substrates for lipid acylation in other membranes. In order to assess whether lipid acylation may have a role in plastid lipid metabolism, we have studied the incorporation of radiolabelled fatty acids from acyl-CoAs into lipids in isolated, intact pea chloroplasts. The labelled lipids were phosphatidylcholine (PC), phosphatidylglycerol (PG), phosphatidylinositol and free fatty acids. With oleoyl-CoA, the fatty acid was incorporated preferably into the sn-2 position of PC and the acylation activity mainly occurred in fractions enriched in inner chloroplast envelope. Added lysoPC stimulated the activity. With palmitoyl-CoA, the fatty acid was incorporated primarily into the sn-1 position of PG and the reaction occurred at the surface of the chloroplasts. As chloroplast-synthesized PG generally contains 16C fatty acids in the sn-2 position, we propose that the acylation of PG studied represents activities present in a domain of the endoplasmic reticulum or an endoplasmic reticulum-derived fraction that is associated with chloroplasts and maintains this association during isolation. This domain or fraction contains a discreet population of lipid metabolizing activities, different from that of bulk endoplasmic reticulum, as shown by that with isolated endoplasmic reticulum, acyl-CoAs strongly labelled phosphatidic acid and phosphatidylethanolamine, lipids that were never labelled in the isolated chloroplasts.
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| 12. |
- Kjellberg, J. Magnus, 1972, et al.
(författare)
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GTP-dependent phosphorylation and GTPγS-dependent thiophosphorylation of proteins and lipids in chloroplasts isolated from leaves of spinach (Spinacia oleracea)
- 2004
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Ingår i: Plant Science. - : Elsevier BV. - 0168-9452. ; 166:3, s. 601-607
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the interaction of GTP and its slowly-hydrolysable analogue, GTPγS, with isolated chloroplast envelope, stroma and thylakoids from spinach (Spinacia oleracea). We used a filter assay to monitor [35S]GTPγS-dependent labelling of the chloroplast fractions. All fractions were labelled by [35S]GTPγS and the labelling was competed by unlabelled GTPγS, GTP and GDP over ATP and GMP. The label associated with the chloroplast fractions was, at least partly, covalent thiophosphate labelling of proteins as well as traces of lipid labelling. The pattern of [35S]GTPγS-dependent protein thiophosphorylation differed from [35S]ATPγS dependent thiophosphorylation as well as from [γ-32P]GTP and [γ-32P]ATP dependent protein phosphorylation. Incubation of chloroplast fractions with [γ-32P]GTP also resulted in heavy labelling of several lipids and lipid phosphorylation was markedly more prominent than lipid thiophosphorylation. The results are discussed in relation to the possible roles of guanine nucleotides in the regulation of thylakoid biogenesis
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| 13. |
- Larsson, Karin E., 1958, et al.
(författare)
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LysoPC acyltransferase/PC transacylase activities in plant plasma membrane and plasma membrane-associated endoplasmic reticulum
- 2007
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Ingår i: BMC Plant Biology. - 1471-2229.
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Tidskriftsartikel (refereegranskat)abstract
- Background The phospholipids of the plant plasma membrane are synthesized in the endoplasmic reticulum (ER). The majority of these lipids reach the plasma membrane independently of the secretory vesicular pathway. Phospholipid delivery to the mitochondria and chloroplasts of plant cells also bypasses the secretory pathway and here it has been proposed that lysophospholipids are transported at contact sites between specific regions of the ER and the respective organelle, followed by lysophospholipid acylation in the target organelle. To test the hypothesis that a corresponding mechanism operates to transport phospholipids to the plasma membrane outside the secretory pathway, we investigated whether lysolipid acylation occurs also in the plant plasma membrane and whether this membrane, like the chloroplasts and mitochondria, is in close contact with the ER. Results The plant plasma membrane readily incorporated the acyl chain of acyl-CoA into phospholipids. Oleic acid was preferred over palmitic acid as substrate and acyl incorporation occurred predominantly into phosphatidylcholine (PC). Phospholipase A2 stimulated the reaction, as did exogenous lysoPC when administered in above critical micellar concentrations. AgNO3 was inhibitory. The lysophospholipid acylation reaction was higher in a membrane fraction that could be washed off the isolated plasma membranes after repeated freezing and thawing cycles in a medium with lowered pH. This fraction exhibited several ER-like characteristics. When plasma membranes isolated from transgenic Arabidopsis expressing green fluorescent protein in the ER lumen were observed by confocal microscopy, membranes of ER origin were associated with the isolated plasma membranes. Conclusions We conclude that a lysoPC acylation activity is associated with plant plasma membranes and cannot exclude a PC transacylase activity. It is highly plausible that the enzyme(s) resides in a fraction of the ER, closely associated with the plasma membrane, or in both. We suggest that this fraction might be the equivalent of the mitochondria associated membrane of ER origin that delivers phospholipids to the mitochondria, and to the recently isolated ER-derived membrane fraction that is in close contact with chloroplasts. The in situ function of the lysoPC acylation/PC transacylase activity is unknown, but involvement in lipid delivery from the ER to the plasma membrane is suggested.
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| 14. |
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| 15. |
- Sandelius, Anna Stina, 1952, et al.
(författare)
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Transient increase in CSF GAP-43 concentration after ischemic stroke.
- 2018
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Ingår i: BMC neurology. - : Springer Science and Business Media LLC. - 1471-2377. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- Cerebrospinal fluid (CSF) biomarkers reflect ongoing processes in the brain. Growth-associated protein 43 (GAP-43) is highly upregulated in brain tissue shortly after experimental ischemia suggesting the CSF GAP-43 concentration may be altered in ischemic brain disorders. CSF GAP-43 concentration is elevated in Alzheimer's disease patients; however, patients suffering from stroke have not been studied previously.The concentration of GAP-43 was measured in longitudinal CSF samples from 28 stroke patients prospectively collected on days 0-1, 2-4, 7-9, 3weeks, and 3-5months after ischemia and cross-sectionally in 19 controls. The stroke patients were clinically evaluated using a stroke severity score system. The extent of the brain lesion, including injury size and degrees of white matter lesions and atrophy were evaluated by CT and magnetic resonance imaging.Increased GAP-43 concentration was detected from day 7-9 to 3weeks after stroke, compared to day 1-4 and to levels in the control group (P=0.02 and P=0.007). At 3-5months after stroke GAP-43 returned to admission levels. The initial increase in GAP-43 during the nine first days was associated to stroke severity, the degree of white matter lesions and atrophy and correlated positively with infarct size (rs=0.65, P=0.001).The transient increase of CSF GAP-43 is important to take into account when used as a biomarker for other neurodegenerative diseases such as Alzheimer's disease. Furthermore, GAP-43 may be a marker of neuronal responses after stroke and additional studies confirming the potential of CSF GAP-43 to reflect severity and outcome of stroke in larger cohorts are warranted.
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| 16. |
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The Chloroplast - Interactions with the Environment
- 2009
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Chloroplasts are vital for life as we know it. At the leaf cell level, it is common knowledge that a chloroplast interacts with its surroundings – but this knowledge is often limited to the benefits of oxygenic photosynthesis and that chloroplasts provide reduced carbon, nitrogen and sulphur. This book presents the intricate interplay between chloroplasts and their immediate and more distant environments. The topic is explored in chapters covering aspects of evolution, the chloroplast/cytoplasm barrier, transport, division, motility and bidirectional signalling. Taken together, the contributed chapters provide an exciting insight into the complexity of how chloroplast functions are related to cellular and plant-level functions. The recent rapid advances in the presented research areas, largely made possible by the development of molecular techniques and genetic screens of an increasing number of plant model systems, make this interaction a topical issue.
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| 17. |
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| 18. |
- Tjellström, Henrik, 1974, et al.
(författare)
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Lipid asymmetry in plant plasma membranes : phosphate deficiency-induced phospholipid replacement is restricted to the cytosolic leaflet
- 2010
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Ingår i: The FASEB Journal. - : Wiley. - 0892-6638 .- 1530-6860. ; 24:4, s. 1128-1138
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Tidskriftsartikel (refereegranskat)abstract
- As in other eukaryotes, plant plasma membranes contain sphingolipids, phospholipids, and free sterols. In addition, plant plasma membranes also contain sterol derivatives and usually <5 mol% of a galactolipid, digalactosyldiacylglycerol (DGDG). We earlier reported that compared to fully fertilized oats (Avena sativa), oats cultivated without phosphate replaced up to 70 mol% of the root plasma membrane phospholipids with DGDG. Here, we investigated the implications of a high DGDG content on membrane properties. The phospholipid-to-DGDG replacement almost exclusively occurred in the cytosolic leaflet, where DGDG constituted up to one-third of the lipids. In the apoplastic (exoplasmic) leaflet, as well as in rafts, phospholipids were not replaced by DGDG, but by acylated sterol glycosides. Liposome studies revealed that the chain ordering in free sterol/phospholipid mixtures clearly decreased when > 5mol% DGDG was included. As both the apoplastic plasma membrane leaflet (probably the major water permeability barrier) and rafts both contain only trace amounts of DGDG, we conclude that this lipid class is not compatible with membrane functions requiring a high degree of lipid order. By not replacing phospholipids site specifically with DGDG, negative functional effects of this lipid in the plasma membrane are avoided.
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| 19. |
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| 20. |
- Tjellström, Henrik, 1974, et al.
(författare)
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Membrane phospholipids as a phosphate reserve: the dynamic nature of phospholipid-to-digalactosyl diacylglycerol exchange in higher plants.
- 2008
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Ingår i: Plant Cell & Environment. ; 31:10, s. 1388-1398
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT It is well established that phosphate deficiency induces the replacement of membrane phospholipid with non-phosphorous lipids in extra-plastidial membranes (e.g. plasma membrane, tonoplast, mitochondria). The predominant replacement lipid is digalactosyl diacylglycerol (DGDG). This paper reports that the phospholipid-to-DGDG replacement is reversible, and that when oat seedlings are re-supplied with radio-labelled phosphate, it is initially recovered primarily in phosphatidylcholine (PC). Within 2 d, the shoot contains more than half of the lipid-associated radiolabel, reflecting phosphate translocation. Oat was also cultivated in different concentrations of phosphate and the DGDG/PC ratio in roots and phospholipase activities in isolated plasma membranes was assayed after different times of cultivation. The DGDG/PC ratio in root tissue correlated more closely with plasma membrane-localized phospholipase D, yielding phosphatidic acid (PA), than with plasma membrane-localized PA phosphatase, the activity that results in a decreased proportion of phospolipids. The lipid degradation data did not reflect a significant involvement of phospholipase C, although a putative phospholipase C analogue, non-specific phospholipase C4 (NPC4), was present in oat roots. The correlation between increased phospholipase D activity and DGDG/PC ratio is consistent with a model where phospholipid-to-DGDG replacement involves formation of PA that readily is removed from the plasma membrane for further degradation elsewhere.
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