| 1. |
- Boerjan, W., et al.
(författare)
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Superroot, a recessive mutation in Arabidopsis, confers auxin overproduction
- 1995
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Ingår i: The Plant Cell. - : JSTOR. - 1040-4651 .- 1532-298X. ; 7:9, s. 1405-1419
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Tidskriftsartikel (refereegranskat)abstract
- We have isolated seven allelic recessive Arabidopsis mutants, designated superroot (sur1-1 to sur1-7), displaying several abnormalities reminiscent of auxin effects. These characteristics include small and epinastic cotyledons, an elongated hypocotyl in which the connection between the stele and cortical and epidermal cells disintegrates, the development of excess adventitious and lateral roots, a reduced number of leaves, and the absence of an inflorescence. When germinated in the dark, sur1 mutants did not develop the apical hook characteristic of etiolated seedlings, We were able to phenocopy the Sur1(-) phenotype by supplying auxin to wild-type seedlings, to propagate sur7 explants on phytohormone-deficient medium, and to regenerate shoots from these explants by the addition of cytokinins alone to the culture medium. Analysis by gas chromatography coupled to mass spectrometry indicated increased levels of both free and conjugated indole-3-acetic acid. sur1 was crossed to the mutant axr2 and the altered-auxin response mutant ctr1. The phenotype of both double mutants was additive. The sur1 gene was mapped on chromosome 2 at 0.5 centimorgans from the gene encoding phytochrome B.
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| 2. |
- Creusot, F., et al.
(författare)
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The CIC YAC library: Sizing of the clones and determination of clones carrying repeated DNA sequences.
- 1995
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Ingår i: The Plant Journal. - 0960-7412 .- 1365-313X. ; 8:5, s. 763-770
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Tidskriftsartikel (refereegranskat)abstract
- A new Arabidopsis thaliana (ecotype Columbia) genomic library has been constructed in Yeast Artificial Chromosomes: the CIC library (for CEPH, INRA and CNRS). Optimization of plant culture conditions and protoplast preparation allowed the recovery of large amounts of viable protoplasts. Mechanical shearing of DNA was minimized by isolation of DNA from protoplasts embedded in agarose. Cloning of large inserts was favored by including two successive size fractionation steps (after partial EcoRI digestion and after ligation with the vector arms), which selected DNA fragments larger than 350 kb. The library consists of 1152 clones with an average insert size of 420 kb. Clones carrying chloroplast DNA and various nuclear repeated sequences have been identified. Twenty-one per cent of the clones are found to contain chloroplast DNA. Therefore, the library represents around four nuclear genome equivalents. The clones containing 5S rDNA genes, 18S-25S rDNA sequences and the 180 bp paracentromeric repeated element account for 3.6%, 8.9% and 5.8%, respectively. Only one clone was found to carry the 160 bp paracentromeric repeated element. Given the smaller size of clones carrying Arabidopsis repeated DNA, the average size of remaining clones is around 480 kb. The library was screened by PCR amplification using pairs of primers corresponding to sequences dispersed in the genome. Seventy out of 76 pairs of primers identified from one to seven YAC clones. Thus at least 92% of the genome is represented in the CIC library. The survey of the library for clones containing unlinked DNA sequences indicates that the proportion of chimeric clones is lower than 10%.
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| 3. |
- Seo, M., et al.
(författare)
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Higher activity of an aldehyde oxidase in the auxin-overproducing superroot1 mutant of Arabidopsis thaliana
- 1998
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 116:2, s. 687-693
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Tidskriftsartikel (refereegranskat)abstract
- Aldehyde oxidase (AO; EC 1.2.3.1) activity was measured in seedlings of wild type or an auxin-overproducing mutant, superroot1 (sur1), of Arabidopsis thaliana. Activity staining for AO after native polyacrylamide gel electrophoresis separation of seedling extracts revealed that there were three major bands with AO activity (AO1-3) in wild-type and mutant seedlings. One of them (AO1) had a higher substrate preference for indole-3-aldehyde. This AO activity was significantly higher in sur1 mutant seedlings than in the wild type. The difference in activity was most apparent 7 d after germination, the same time required for the appearance of the remarkable sur1 phenotype, which includes epinastic cotyledons, elongated hypocotyls, and enhanced root development. Higher activity was observed in the root and hypocotyl region of the mutant seedlings. We also assayed the indole-3-acetaldehyde oxidase activity in extracts by high-performance liquid chromatography detection of indole-3-acetic acid (IAA). The activity was about 5 times higher in the extract of the sur1 seedlings, indicating that AO1 also has a substrate preference for abscisic aldehyde. Treatment of the wild-type seedlings with picloram or IAA caused no significant increase in AO1 activity. This result suggested that the higher activity of AO1 in sur1 mutant seedlings was not induced by IAA accumulation and, thus, strongly supports the possible role of AO1 in IAA biosynthesis in Arabidopsis seedlings.
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| 4. |
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| 5. |
- Bellini, M, et al.
(författare)
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Temporal coherence of ultrashort high-order harmonic pulses
- 1998
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Ingår i: Physical Review Letters. - 1079-7114. ; 81:2, s. 297-300
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the temporal coherence of high-order harmonics (up to the 15th order) produced by focusing 100 fs laser pulses into an argon gas jet. We measure the visibility of the interference fringes, produced when two spatially separated harmonic sources interfere in the far field, as a function of the time delay between the two sources. In general, we find long coherence times, comparable to the expected pulse durations of the harmonics. For some of the harmonics, the interference pattern exhibits two regions, with significantly different coherence times. These results are interpreted in terms of different electronic trajectories contributing to harmonic generation. [S0031-9007(98)05569-7].
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| 6. |
- Berg, M, et al.
(författare)
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A compact range telescope for K+ measurements
- 1996
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Ingår i: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT. - 0168-9002. ; 381:2-3, s. 267-274
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Tidskriftsartikel (refereegranskat)abstract
- We present range telescopes for measurements of low energy K+ mesons together with first in-beam results. The hardware trigger, based on the observation of the mu(+) from the K+ --> mu(-) + nu(mu) decay channel, is designed for subthreshold hadron-nucleus
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| 7. |
- Delarue, M., et al.
(författare)
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cristal mutations in Arabidopsis confer a genetically heritable, recessive, hyperhydric phenotype
- 1997
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Ingår i: Planta. - : Springer Science and Business Media LLC. - 0032-0935 .- 1432-2048. ; 202:1, s. 51-61
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Tidskriftsartikel (refereegranskat)abstract
- A new class of recessive Arabidopsis mutants, designated cristal (cii) has been isolated which display several abnormalities reminiscent of hyperhydric symptoms. These characteristics include translucent and wrinkled cotyledons and leaves, abnormal chloroplast organization, a reduced amount of chlorophyll, a reduced dry weight and a decreased number of palisade cells in the leaves accompanied by an increase of intercellular space, and therefore give a vitreous appearance to the aerial part. The phenotype is also dependent on the culture medium water potential. The cril gene was mapped on chromosome 4 close to the DHS1 marker.
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| 8. |
- Delarue, M., et al.
(författare)
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Sur2 mutations of Arabidopsis thaliana define a new locus involved in the control of auxin homeostasis
- 1998
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Ingår i: The Plant Journal. - 0960-7412 .- 1365-313X. ; 14:5, s. 603-611
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Tidskriftsartikel (refereegranskat)abstract
- A new auxin homeostasis gene in Arabidopsis called SUR2 has been identified. This gene, mapped to the bottom of chromosome 4, is defined by two recessive nuclear mutants designated superroot2 (sur2), which display several abnormalities reminiscent of auxin effects. A number of these characteristics are similar to the phenotype of the previously described auxin-overproducing mutant superroot1 (sur1); however, several lines of evidences reveal that the SUR2 gene defines a new key point in the regulation of endogenous auxin concentrations. The phenotype of the sur1 sur2 double mutant is additive. Analysis by gas chromatography coupled to mass spectrometry indicated increased levels of free indole-3-acetic acid correlated with a decreased level of bound auxin in the sur2 mutant. These results suggest that SUR2 may be involved in the control of auxin conjugation.
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| 9. |
- Elmer, R, et al.
(författare)
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K+ emission in symmetric heavy ion reactions at subthreshold energies
- 1996
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Ingår i: PHYSICAL REVIEW LETTERS. - : AMER INST PHYSICS. ; 77:24, s. 4884-4886
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Tidskriftsartikel (refereegranskat)abstract
- Subthreshold K+ production cross sections have been measured in symmetric Ne + NaF, Ni + Ni, and Au + Au collisions at 1.0A GeV. The mass dependence is strong, close to A(2). The angular distributions are nonisotropic in the center-of-mass system. Introdu
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| 10. |
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