| 1. |
- Cañas, Rafael A, et al.
(författare)
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Molecular and functional analyses support a role of Ornithine-{delta}-aminotransferase in the provision of glutamate for glutamine biosynthesis during pine germination
- 2008
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 148:1, s. 77-88
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Tidskriftsartikel (refereegranskat)abstract
- We report the molecular characterization and functional analysis of a gene (PsdeltaOAT) from Scots pine (Pinus sylvestris) encoding Orn-delta-aminotransferase (delta-OAT; EC 2.6.1.13), an enzyme of arginine metabolism. The deduced amino acid sequence contains a putative N-terminal signal peptide for mitochondrial targeting. The polypeptide is similar to other delta-OATs from plants, yeast, and mammals and encoded by a single-copy gene in pine. PsdeltaOAT encodes a functional delta-OAT as determined by expression of the recombinant protein in Escherichia coli and analysis of the active enzyme. The expression of PsdeltaOAT was undetectable in the embryo, but highly induced at early stages of germination and seedling development in all different organs. Transcript levels decreased in later developmental stages, although an increase was observed in lignified stems of 90-d-old plants. An increase of delta-OAT activity was observed in germinating embryos and seedlings and appears to mirror the observed alterations in PsdeltaOAT transcript levels. Similar expression patterns were also observed for genes encoding arginase and isocitrate dehydrogenase. Transcripts of PsdeltaOAT and the arginase gene were found widely distributed in different cell types of pine organs. Consistent with these results a metabolic pathway is proposed for the nitrogen flow from the megagametophyte to the developing seedling, which is also supported by the relative abundance of free amino acids in embryos and seedlings. Taken together, our data support that delta-OAT plays an important role in this process providing glutamate for glutamine biosynthesis during early pine growth.
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| 2. |
- Karim, Sazzad, et al.
(författare)
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Improved drought tolerance without undesired side effects in transgenic plants producing trehalose
- 2007
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Ingår i: Plant Molecular Biology. - : Springer Science and Business Media LLC. - 0167-4412 .- 1573-5028. ; 64:4, s. 371-386
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Tidskriftsartikel (refereegranskat)abstract
- Most organisms naturally accumulating trehalose upon stress produce the sugar in a two-step process by the action of the enzymes trehalose-6-phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP). Transgenic plants overexpressing TPS have shown enhanced drought tolerance in spite of minute accumulation of trehalose, amounts believed to be too small to provide a protective function. However, overproduction of TPS in plants has also been found combined with pleiotropic growth aberrations. This paper describes three successful strategies to circumvent such growth defects without loosing the improved stress tolerance. First, we introduced into tobacco a double construct carrying the genes TPS1 and TPS2 (encoding TPP) from Saccharomyces cerevisiae. Both genes are regulated by an Arabidopsis RuBisCO promoter from gene AtRbcS1A giving constitutive production of both enzymes. The second strategy involved stress-induced expression by fusing the coding region of ScTPS1 downstream of the drought-inducible Arabidopsis AtRAB18 promoter. In transgenic tobacco plants harbouring genetic constructs with either ScTPS1 alone, or with ScTPS1 and ScTPS2 combined, trehalose biosynthesis was turned on only when the plants experienced stress. The third strategy involved the use of AtRbcS]A promoter together with a transit peptide in front of the coding sequence of ScTPS1, which directed the enzyme to the chloroplasts. This paper confirms that the enhanced drought tolerance depends on unknown ameliorated water retention as the initial water status is the same in control and transgenic plants and demonstrates the influence of expression of heterologous trehalose biosynthesis genes on Arabidopsis root development.
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| 3. |
- Råberg, Ulrika, et al.
(författare)
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Early soft rot colonization of Scots sapwood pine in above-ground exposure
- 2009
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Ingår i: International Biodeterioration & Biodegradation. - : Elsevier BV. - 0964-8305 .- 1879-0208. ; 63:2, s. 236-240
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Tidskriftsartikel (refereegranskat)abstract
- The early colonization of Scots pine (Pinus sylvestris L) sapwood exposed above ground (staple bed) was studied. Two different types of exposures were used, one in an open field and the other in a shaded field. Decay type and degree of degradation due to soft rot and mass and strength loss of wood were correlated. Fungal species in Scots pine sapwood were identified by sequencing, using the fungal nuclear ribosomal DNA (nrDNA) after 24 months. The most abundant decay type found was soft rot, which also agreed with the mass loss (7-8%). Pine sapwood did not differ significantly between the two sites regarding the average mass loss during the time of exposure. The early colonization of wood by soft rot fungi together with mass loss indicates that this fungal type might be more common in above-ground conditions than recognized earlier.
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| 4. |
- Yin, Xiao-Jun, et al.
(författare)
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Ubiquitin lysine 63 chain forming ligases regulate apical dominance in Arabidopsis
- 2007
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Ingår i: The Plant Cell. - Rockville : American society of plant biologists. - 1040-4651 .- 1532-298X. ; 19:6, s. 1898-1911
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Tidskriftsartikel (refereegranskat)abstract
- Lys-63-linked multiubiquitin chains play important roles in signal transduction in yeast and in mammals, but the functions for this type of chain in plants remain to be defined. The RING domain protein RGLG2 (for RING domain Ligase2) from Arabidopsis thaliana can be N-terminally myristoylated and localizes to the plasma membrane. It can form Lys-63-linked multiubiquitin chains in an in vitro reaction. RGLG2 has overlapping functions with its closest sequelog, RGLG1, and single mutants in either gene are inconspicuous. rglg1 rglg2 double mutant plants exhibit loss of apical dominance and altered phyllotaxy, two traits critically influenced by the plant hormone auxin. Auxin and cytokinin levels are changed, and the plants show a decreased response to exogenously added auxin. Changes in the abundance of PIN family auxin transport proteins and synthetic lethality with a mutation in the auxin transport regulator BIG suggest that the directional flow of auxin is modulated by RGLG activity. Modification of proteins by Lys-63-linked multiubiquitin chains is thus important for hormone-regulated, basic plant architecture.
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| 5. |
- Bautista, Rocío, et al.
(författare)
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Toward a Pinus pinaster bacterial artificial chromosome library
- 2007
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Ingår i: Annals of Forest Science. - : Springer Science and Business Media LLC. - 1286-4560 .- 1297-966X. ; 64:8, s. 855-864
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Tidskriftsartikel (refereegranskat)abstract
- Conifers are of great economic and ecological importance, but little is known concerning their genomic organization. This study is an attempt to obtain high-quality high-molecular-weight DNA from Pinus pinaster cotyledons and the construction of a pine BAC library. The preparation incorporates modifications like low centrifugation speeds, increase of EDTA concentration for plug maintenance, use of DNase inhibitors to reduce DNA degradation, use of polyvinylpyrrolidone and ascorbate to avoid secondary metabolites, and a brief electrophoresis of the plugs prior to their use. A total of 72 192 clones with an average insert size of 107 kb, which represents an equivalent of 11X pine haploid genomes, were obtained. The proportions of clones lacking inserts or containing chloroplast DNA are both approximately 1.6%. The library was screened with cDNA probes for seven genes, and two clones containing Fd-GOGAT sequences were found, one of them seemingly functional. Ongoing projects aimed at constructing a pinebacterial artificial chromosome library may benefit from the methods described here.
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| 6. |
- Andreazza, N, et al.
(författare)
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Production of imidazole alkaloids in cell cultures of jaborandi as affected by the medium pH
- 2009
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Ingår i: Biotechnology letters. - : Springer. - 0141-5492 .- 1573-6776. ; 31:4, s. 607-614
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Tidskriftsartikel (refereegranskat)abstract
- The effect of pH (from 4.8 to 9.8) on the production of pilosine and pilocarpine and on their partition between cell and medium was studied in two lineages (P and PP) of Pilocarpus microphyllus cell suspension cultures. Highest mass accumulation was observed at high pHs and both lineages produced pilocarpine while only lineage PP produced pilosine. Both alkaloids were released in the medium but higher accumulation occurred in the cells. The highest production of pilocarpine was at pH 8.8-9.8 in both cell lineages. Other imidazole alkaloids were also identified in both lineages. At all pHs tested, the pH in the media cultures tended to stabilize around 6 after 10-15 days of cultivation. NO(3) (-) and NH(4) (+) variation in the media might partially explain the pH stabilization.
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| 7. |
- Bergqvist, AS, et al.
(författare)
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Detection of the hyaluronan receptor CD44 in the bovine oviductal epithelium
- 2005
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Ingår i: Journal of reproduction and development. - Ibaraki , Japan : Society for Reproduction and Development. - 0916-8818 .- 1348-4400. ; 51:4, s. 445-453
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Tidskriftsartikel (refereegranskat)abstract
- Hyaluronan is involved in fundamental reproductive events such as sperm storage in the female reproductive tract, fertilization, and early embryo development, these functions are presumably mediated by its major cell surface receptor, CD44. The present study was conducted to investigate the presence and localization of CD44 in the bovine oviductal epithelium, using immunohistochemical and Western blot methods on tissue sections and epithelial cell extracts collected from the uterotubal junction (UTJ), isthmus, and ampulla of animals in the oestrus or luteal phase of the oestrous cycle. While positive immunolabelling for CD44 was found on the ad-luminal surface and supra-nuclear region of epithelial cells in all tubal segments investigated, in the UTJ, there were epithelial cells in which the entire cytoplasm positively stained. We found no differences in terms of CD44-positive staining between the different stages of the oestrous cycle. Presence of CD44 was detected by Western blotting in the tubal epithelium as a single band at 200 kDa. Although it appeared in all tubal segments, the expression of CD44 protein was more accentuated in the sperm reservoir (UTJ) than in the other segments. This is the first time CD44 has been detected in the epithelium of the tubal sperm reservoir in cattle, suggesting a pathway for the action of hyaluronan in this segment.
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| 8. |
- Crutsinger, G M, et al.
(författare)
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Ecosystem retrogression leads to increased insect abundance and herbivory across an island chronosequence
- 2008
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Ingår i: Functional Ecology. - : John Wiley & Sons. - 0269-8463 .- 1365-2435. ; 22:5, s. 816-823
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Tidskriftsartikel (refereegranskat)abstract
- 1. Ecosystem retrogression, the decline-phase of ecosystem development, occurs during the long-term absence of catastrophic disturbance. It usually involves increased nutrient limitation over time, and leads to reductions in primary productivity, decomposition, and nutrient cycling.2. As a consequence, retrogression can alter the quality and abundance of host plants as food resources, but little is known about how these changes influence herbivore densities and foliage consumption.3. In this study, we used a 5000-year-old chronosequence of forested islands in northern Sweden on which retrogression occurs in the absence of lightning-induced wildfire. We asked whether retrogression affected the abundance and herbivory of a dominant herbivorous weevil (Deporaus betulae) and the quality and productivity of a dominant host-tree, mountain birch (Betula pubescens).4. Betula pubescens trees on retrogressed islands were less productive and produced smaller, tougher leaves that were lower in nutrients and higher in secondary metabolites than did those trees on earlier-successional islands.5. Despite the lower density and what ecologists might perceive as poorer quality of host plants, we observed several-fold higher weevil abundance and damage on retrogressed islands. This suggests that weevils might prefer the poorer quality leaves with higher secondary metabolites that occur on nutrient stressed host trees.6. Our results show that ecosystem retrogression increases susceptibility of B. pubescens trees to attack by herbivorous weevils.7. Our study provides evidence that ecosystem retrogression and associated shifts in the quantity and quality of available resources can operate as an important driver of abundance of a dominant insect herbivore.
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| 9. |
- Geibler, Justus von, et al.
(författare)
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Accounting for the social dimension of sustainability: experiences from the biotechnology industry
- 2006
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Ingår i: Business Strategy and the Environment. - : Wiley. - 1099-0836 .- 0964-4733. ; 15:5, s. 334-346
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Tidskriftsartikel (refereegranskat)abstract
- Accounting for the social dimension of sustainability proves to be a challenge for corporate practitioners, due to its intangible, qualitative nature and lack of consensus on relevant criteria. We suggest a semi-quantitative approach based on stakeholder involvement to identify relevant aspects for a sector specific assessment of the social dimension. Our case study on biotechnology illustrates that the dialogue with internal and external stakeholders enabled the creation of a key performance indicator (KPI) set to account for social sustainability in the early design stages of biotechnological processes and product development. Indicators for eight aspects are identified for the social assessment: health and safety, quality of working conditions, impact on employment, education and training, knowledge management, innovation potential, customer acceptance and societal product benefit, and social dialogue. We describe the integration of the KPI set in a software application, tailor made for practitioners of the sector, and highlight first user experiences. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment.
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| 10. |
- Olivain, C, et al.
(författare)
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Colonization of tomato root by pathogenic and nonpathogenic Fusarium oxysporum strains inoculated together and separately into the soil
- 2006
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 72:2, s. 1523-1531
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Tidskriftsartikel (refereegranskat)abstract
- In soil, fungal colonization of plant roots has been traditionally studied by indirect methods such as microbial isolation that do not enable direct observation of infection sites or of interactions between fungal pathogens and their antagonists. Confocal laser scanning microscopy was used to visualize the colonization of tomato roots in heat-treated soil and to observe the interactions between a nonpathogenic strain, Fo47, and a pathogenic strain, Fo18, inoculated onto tomato roots in soil. When inoculated separately, both fungi colonized the entire root surface, with the exception of the apical zone. When both strains were introduced together, they both colonized the root surface and were observed at the same locations. When Fo47 was introduced at a higher concentration than Fo18, it colonized much of the root surface, but hyphae of Fo18 could still be observed at the same location on the root. There was no exclusion of the pathogenic strain by the presence of the nonpathogenic strain. These results are not consistent with the hypothesis that specific infection sites exist on the root for Fusarium oxysporum and instead support the hypothesis that competition occurs for nutrients rather than for infection sites.
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