| 1. |
- Alexandersson, Erik, et al.
(författare)
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Whole gene family expression and drought stress regulation of aquaporins
- 2005
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Ingår i: Plant Molecular Biology. - : Springer Science and Business Media LLC. - 1573-5028 .- 0167-4412. ; 59:3, s. 469-484
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Tidskriftsartikel (refereegranskat)abstract
- Since many aquaporins (AQPs) act as water channels, they are thought to play an important role in plant water relations. It is therefore of interest to study the expression patterns of AQP isoforms in order to further elucidate their involvement in plant water transport. We have monitored the expression patterns of all 35 Arabidopsis AQPs in leaves, roots and flowers by cDNA microarrays, specially designed for AQPs, and by quantitative real-time reverse transcriptase PCR (Q-RT-PCR). This showed that many AQPs are pre-dominantly expressed in either root or flower organs, whereas no AQP isoform seem to be leaf specific. Looking at the AQP subfamilies, most plasma membrane intrinsic proteins (PIPs) and some tonoplast intrinsic proteins (TIPs) have a high level of expression, while NOD26-like proteins (NIPs) are present at a much lower level. In addition, we show that PIP transcripts are generally down-regulated upon gradual drought stress in leaves, with the exception of AtPIP1;4 and AtPIP2;5, which are up-regulated. AtPIP2;6 and AtSIP1;1 are constitutively expressed and not significantly affected by the drought stress. The transcriptional down-regulation of PIP genes upon drought stress could also be observed on the protein level.
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| 2. |
- Gustavsson, Sofia, et al.
(författare)
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A novel plant major intrinsic protein in Physcomitrella patens most similar to bacterial glycerol channels
- 2005
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 1532-2548 .- 0032-0889. ; 139:1, s. 287-295
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Tidskriftsartikel (refereegranskat)abstract
- A gene encoding a novel fifth type of major intrinsic protein (MIP) in plants has been identified in the moss Physcomitrella patens. Phylogenetic analyses show that this protein, GlpF-like intrinsic protein (GIP1;1), is closely related to a subclass of glycerol transporters in bacteria that in addition to glycerol are highly permeable to water. A likely explanation of the occurrence of this bacterial-like MIP in P. patens is horizontal gene transfer. The expressed P. patens GIP1;1 gene contains five introns and encodes a unique C-loop extension of approximately 110 amino acid residues that has no obvious similarity with any other known protein. Based on alignments and structural comparisons with other MIPs, GIP1;1 is suggested to have retained the permeability for glycerol but not for water. Studies on heterologously expressed GIP1;1 in Xenopus laevis oocytes confirm the predicted substrate specificity. Interestingly, proteins of one of the plant-specific subgroups of MIPs, the NOD26-like intrinsic proteins, are also facilitating the transport of glycerol and have previously been suggested to have evolved from a horizontally transferred bacterial gene. Further studies on localization and searches for GIP1;1 homologs in other plants will clarify the function and significance of this new plant MIP.
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| 3. |
- Gustavsson, Sofia
(författare)
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Plant major intrinsic proteins. Identification and characterization of novel water channel-like protiens.
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Major Intrinsic Proteins, MIPs, constitute a large, ancient superfamily of membrane proteins that are found in all kingdoms of life. Most MIPs facilitate passive diffusion of water across biological membranes (aquaporins), although many channels are also permeable for glycerol and other small uncharged solutes, (aquaglyceroporins). Other substrates reported for specific MIPs are anions, carbon dioxide, arsenic and boric acid. MIPs are predominantly important in processes involving water regulation and osmoregulation, but have also been suggested to be involved in carbohydrate metabolism. In the genome of the model plant Arabidopsis thaliana, 35 MIP-encoding genes were identified. By sequence homology and phylogenetic analyses, these genes were divided into four subfamilies, Plasma membrane Intrinsic Proteins, PIPs, Tonoplast Intrinsic Proteins, TIPs, Nod26-like Intrinsic Proteins, NIPs, and Small basic Intrinsic proteins, SIPs. Based on the phylogenetic analyses and the already commonly used names, a new nomenclature, which now is widely accepted, was proposed. The SIPs form the most recently identified subfamily, and this divergent family is also the poorest characterized. The constriction region of SIPs is unlike filters of both aguaglyceroporins and aquaporins, suggesting different substrates than glycerol or water. Expression studies by promoter::GUS fusions imply that SIP1;1 is expressed in roots, trichomes, stigma, style and stamen. Vascular root localization of SIP1;1 was also observed on the protein level by immunogold labeling, which also labeled guard cells in leaves. SIP2;1 was also localized in guard cells in addition to roots, predominantly in the center of the vasculature. The subcellular localization was investigated by aqueous two-phase partitioning and immunoblotting. Both SIP1;1 and SIP2;1 appear in the plasma membrane fraction when isolated from leaves, but mainly in the fraction containing internal membranes when isolated from roots. Water and glycerol permeability for SIP1;1 and SIP2;1 was investigated by heterologous expression in Xenopus laevis oocytes, but no permeability for either molecule could be observed. In the moss Physcomitrella patens a MIP more similar to bacterial aquaglyceroporins than to any other known plant MIP was identified. Most likely, this protein, GIP1;1, was recruited by plants from bacteria by horizontal gene transfer. GIP1;1 (GIP for GlpF-like Intrinsic Protein) was predicted to be a glycerol selective channel, which subsequently was confirmed after heterologous expression in Xenopus oocytes.
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| 4. |
- Maurice, Christian, et al.
(författare)
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Stabilization of CCA-contaminated soil with iron products : a field experiment
- 2005
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Ingår i: Kalmar ECO-TECH '05. - : Högskolan i Kalmar.
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Konferensbidrag (refereegranskat)abstract
- Chemical stabilization of metals is lately considered as a possible pretreatment for soil contaminated with average levels of trace elements. The element mobility in soil can be altered by adding soil amendments that can adsorb, complex, or co-precipitate trace elements. As a consequence, pollutant spreading from the contaminated soil and effect on the recipient can be reduced. The different contaminants originating from wood impregnation chemicals, e.g. Cu, Cr, and As limit the choice of amendments because e.g. large pH fluctuations and consequent mobilization of Cu or As should be avoided. The results show that the leaching of arsenic is lowest in the lysimeter with 15% Fe3O4. In both lysimeters with untreated soil and with 1% Fe0, the arsenic leaching seems to decrease with the sampling depth. The leaching of copper is generally low. Further the addition of iron seems to increase the leaching of manganese and nickel but to reduce the leaching of zinc. Results from the laboratory experiment show that the arsenic content in the leachate is lowest with the highest mixture of magnetite. Mixing is one of the key issues when discussing the treatment efficiency and possible use of the treated soil. The results so far indicate that magnetite can be used for treatment of CCA contaminated soil also at a large scale. Reduction of both arsenic and copper using a single amendment is challenging as they behave opposite. Magnetite seems to be a promising amendment even though a high amount of amendment needs to be added. Moreover, the potential establishment of reducing conditions at larger depths in the soil is of concern since this might lead to a rapid increase in arsenic leaching.
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| 5. |
- Maurice, Christian, et al.
(författare)
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Techniques for the stabilization and assessment of treated copper- chromium- and arsenic-contaminated soil
- 2007
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Ingår i: Ambio. - 0044-7447 .- 1654-7209. ; 36:6, s. 430–6-
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Tidskriftsartikel (refereegranskat)abstract
- Remediation mainly based on excavation and burial of the contaminated soil is impractical with regard to the large numbers of sites identified as being in need of remediation. Therefore alternative methods are needed for brownfield remediation. This study was conducted to assess a chemical stabilisation procedure of CCA-contaminated soil using iron-containing blaster sand or oxygen scarfing granulate. The stabilisation technique was assessed with regard to the feasibility of mixing ameliorants at an industrial scale and the efficiency of the stabilisation under different redox conditions. The stability was investigated under natural conditions in 1-m3 lysimeters in a field experiment and the effect of redox conditions was assessed in a laboratory experiment (10 l). The treatments with high additions of ameliorant (8 and 17%) were more successful in both the laboratory and field experiments, even though there was enough iron on a stochiometric basis even at the lowest addition rates (0.1 and 1%). The particle size of the iron and the mixing influenced the stabilisation efficiency. The development of anaerobic conditions, simulated by water saturation, increases the fraction of AsIII and, consequently, arsenic mobility. The use of high concentrations of OSG under aerobic conditions increased the concentrations of Ni and Cu in the pore water. However, under anaerobic conditions, it decreased the arsenic leaching compared to the untreated soil and Ni and Cu leaching was not critical. The final destination of the treated soil should govern the amendment choice, e.g. an OSG concentration around 10% may be suitable if the soil is to be landfilled under anaerobic conditions. Alternatively, the soil mixed with 1% BS could be kept under aerobic conditions in a landfill cover or in situ at brownfield site. In addition, the treatment with BS appeared to produce better effects in the long term than with OSG.
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| 6. |
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| 7. |
- Noren, Håkan, 1948, et al.
(författare)
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STAN in clinical practice--the outcome of 2 years of regular use in the city of Gothenburg
- 2006
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Ingår i: Am J Obstet Gynecol. ; 195:1, s. 7-15
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The purpose of this study was to monitor the introduction of the STAN-methodology (Noventa Medical, Moelndal, Sweden). STUDY DESIGN: This was a prospective observational study covering the total population of deliveries at term during 2 years. Four thousand eight hundred and thirty out of 14,687 term pregnancies were monitored using the STAN S 21 fetal heart monitor and the associated clinical guidelines. Cord artery metabolic acidosis, neonatal outcome, and rates of operative deliveries for fetal distress were assessed. RESULTS: The annual rate of STAN usage increased from 28.1% to 37.7% and was associated with a significant reduction in metabolic acidosis rate in the total population from 0.76% to 0.44% (P < .05). The compliance with the clinical guidelines increased in cases requiring intervention. The rates for moderate/severe hypoxic neonatal encephalopathy were consistently low, 0.55 and 0.68 per 1000 deliveries, respectively, and corresponding to previous findings. The rate of operative delivery did not change during the 2 years in the total population. CONCLUSION: Increasing STAN usage provided consistent improvements in fetal outcome equalling those noted in the Swedish randomized controlled trial (RCT) without increasing operative interventions for fetal distress.
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