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  • 1
    Electronic Resource
    Electronic Resource
    Interaction of gibberellins and phytochrome in the control of cowpea epicotyl elongation (1992)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 86 (1992), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The physiological response of cowpea (Vigna sinensis L.) epicotyl explants to far-red light (FR) and its interaction with gibberellins (GAs) have been investigated. The effect of FR and GA1 varied with the age of the seedlings from which the explants were made: for FR, it decreased progressively with age (though the sensitivity of the epicotyls to FR did not change significantly until at least day 11), whereas it remained essentially constant for applied GA1 between days 5 and 9 after sowing. This indicates that the loss of response to FR may be due to a decrease in endogenous GA levels in the epicotyl. For a range of GA1 and GA20 (0.01–1 µg explant−1), both hormones were more active in FR than in R irradiated epicotyls, suggesting that phytochrome may affect GA sensitivity besides GA metabolism. The location of the epicotyl region most sensitive to FR (between 5 and 20 mm below the apex) was different from that to GAs (the upper 10 mm). Nevertheless, FR extended the region responsive to applied GAs, even in paclobutrazol-treated epicotyls where elongation was due entirely to exogenous GAs. This means that modulation of epicotyl elongation by phytochrome, that occurs in a zone different from though overlapping with the GA-sensitive subapical zone, is also mediated by GAs. Growth in the most FR-sensitive region of the epicotyl stimulated by FR or GA1 was due to cell elongation, and in the most GA-sensitive region to both cell division and elongation. The effect of FR and GA1 was negated by colchicine, indicating that microtubules may be involved in the response to both factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1992.860208.x
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  • 2
    Electronic Resource
    Electronic Resource
    Gene expression during two alternative pathways of ovary development in Pisum sativum: fruit development and ovary senescence (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 85 (1992), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Pea ovaries are induced to enter a fruit development pathway involving physiological and morphological changes by pollination or application of plant growth regulators. In the absence of these stimuli, overies stop growing and enter an alternative pathway of senesecence that leads to their degeneration. We have used two dimensional polyacrylamide gel electrophoresis in search of molecular changes underlying fruit development and ovary senescence at the level of total accumulated proteins, newly synthesized proteins, and translatable, RNA populations. We have found changes in gene expression during the processes of ovary formation and ovary senescence. Stimuli that induce fruit set do not appreciably alter the overall patterns of synthesized proteins or translatable RNAs, indicating that fruit development is apparently a natural continuation of ovary formation. However, ovary senescence is an alternative pathway that involves the presence of new RNA messengers and proteins as well as the disappearance of others. These changes were detected earlier than any morphological or structural changes could be observed in the ovary.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1992.tb05265.x
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  • 3
    Electronic Resource
    Electronic Resource
    Development of fertilized ovules and their role in the growth of the pea pod (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 83 (1991), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The histological development of fertilized ovules during fruit-set and development in pea (Pisum sativum L. cv. Alaska) has been investigated. Killing the ovules on day 0 (anthesis) or day 1 prevented fruit-set and resulted in ovary degeneration. When the ovules were destroyed at later stages the ovaries developed, though the rate of growth of the pod was reduced significantly. Pollination in pea occurs normally the day before anthesis, and fertilization of the egg cell 32 to 48 h later. The first divisions of the zygote and endosperm nuclei started simultaneously (ca 48 h after pollination) but the endosperm developed more rapidly than the embryo; the embryo sac cavity was lined with free endosperm nuclei at the time of beginning suspensor elongation. Extracts of endosperm and ovule coats from ovules at day 7 after anthesis showed fruit-set activity in pea, the latter material having about 3 times more activity than the former per ovule basis. These results indicate that fertilization of the ovule is necessary for fruit-set in pea, and that compounds which induce fruit-set are probably synthesized in the ovules following fertilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1991.tb00113.x
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  • 4
    Electronic Resource
    Electronic Resource
    Thermochemistry of molecular complexes. 3. Molecular complexes of iodine with halogenated benzene derivatives (1990)
    s.l. : American Chemical Society
    The @journal of organic chemistry 55 (1990), S. 1122-1125 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00290a063
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  • 5
    Electronic Resource
    Electronic Resource
    Transcriptional regulation of mexR, the repressor of Pseudomonas aeruginosa mexAB-oprM multidrug efflux pump (2002)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 207 (2002), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The transcription start site of mexR, encoding the repressor of the Pseudomonas aeruginosa mexAB-oprM multidrug efflux pump, has been determined by S1 mapping. One signal corresponding to a single promoter has been found, whereas three major signals were observed for the mexA messenger. Further analysis demonstrated that mexA has just one promoter that overlaps with the mexR promoter, with the other two signals observed by S1 probably being the consequence of RNA processing. Transcription of mexR and mexA from the aforementioned promoters is regulated by MexR. We show that bacterial growth phase affects expression of these promoters as well. mexR expression was higher at the exponential growth phase and declined afterwards, whereas mexA expression was triggered at the onset of the stationary growth phase. A model for the regulation of mexR and mexA expression, which includes an analysis of the interplay between both promoters, is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2002.tb11029.x
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  • 6
    Electronic Resource
    Electronic Resource
    Growth of Escherichia coli in acetate as a sole carbon source is inhibited by ankyrin-like repeats present in the 2′,5′-linked oligoadenylate-dependent human RNase L enzyme (1997)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 149 (1997), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Expression of low levels of the 2′,5′-linked oligoadenylate-dependent human RNase L, an enzyme induced by interferons, is highly toxic in Escherichia coli. This protein contains an ankyrin domain responsible for RNase L toxicity. The only known ORF in E. coli containing ankyrin repeats is yjaC in the acetate metabolic cluster. We have investigated if expression of mutant forms of RNase L interfere with metabolism of acetate in E. coli. Our findings demonstrate that E. coli expressing RNase L ankyrin repeats is unable to grow in medium containing acetate as the sole carbon source, while it can grow when expressing other domains of the protein. This defect correlates with a severe decrease in the levels of induction of enzymes in the glyoxylate bypass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1997.tb10316.x
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  • 7
    Electronic Resource
    Electronic Resource
    The end-of-day far-red irradiation increases gibberellin A1 content in cowpea (Vigna sinensis) epicotyls by reducing its inactivation (2000)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 108 (2000), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: It has been shown previously that gibberellins (GAs) mediate the phytochrome (Phy) control of cowpea (Vigna sinensis L.) epicotyl elongation induced by end-of-day (EOD)-far-red light (FR). In the present work, the EOD-FR effect on GA metabolism and GA levels in cowpea has been investigated. GA1, GA8, GA19 and GA20 were identified in epicotyls, and GA1, GA19, GA20 and GA29-catabolite in leaves of 6-day-old cowpea seedlings. The content of GA1 in the epicotyl paralleled the decrease of its growth rate, supporting the hypothesis that this is the GA bioactive in controlling cowpea epicotyl elongation. FR enhanced both the amount of [3H]GA1 in the epicotyl produced from applied [3H]GA20, and that of applied [3H]GA1 that remained unmetabolized in epicotyl explants, suggesting that Phy may regulate the inactivation of GA1. In agreement with this effect of light on GA1 metabolism, the contents of GA1 in the epicotyl remained higher in FR-treated than in R-treated explants. Moreover, in intact seedlings EOD-FR treatment increased both epicotyl elongation and GA1 content in the responsive epicotyl, whereas it was not altered in the leaves. These results show, for the first time, that photostable Phys modulate the stem elongation in light-grown plants by locally controlling the GA1 levels through regulation of its inactivation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2000.t01-1-100413.x
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  • 8
    Electronic Resource
    Electronic Resource
    The ectopic overexpression of a citrus gibberellin 20-oxidase enhances the non-13-hydroxylation pathway of gibberellin biosynthesis and induces an extremely elongated phenotype in tobacco (2001)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 112 (2001), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Transgenic plants of Nicotiana tabacum overexpressing a gibberellin (GA) 20-oxidase cDNA (CcGA20ox1) from citrus, under the control of the 35S promoter, were taller (up to twice) and had larger inflorescences and longer flower peduncles than those of control plants. Hypocotyls of transgenic seedlings were also longer (up to 4 times), and neither the seedlings nor the growing plants elongated further after application of GA3. Hypocotyl and stem lengths were reduced by application of paclobutrazol, and this inhibition was reversed by exogenous GA3. The ectopic overexpression of CcGA20ox1 enhanced the non-13-hydroxylation pathway of GA biosynthesis leading to GA4, apparently at the expense of the early-13-hydroxylation pathway. The level of GA4 (the active GA from the non-13-hydroxylation pathway) in the shoot of transgenic plants was 3–4 times higher than in control plants, whereas that of GA1, formed via the early-13-hydroxylation pathway (the main GA biosynthesis pathway in tobacco), decreased or was not affected. GA4 applied to the culture medium or to the expanding leaves was found to be at least equally active as GA1 on stimulating hypocotyl and stem elongation of tobacco plants. The results suggest that the tall phenotype of tobacco transgenic plants was due to their higher content of GA4, and that the GA response was saturated by the presence of the transgene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2001.1120214.x
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  • 9
    Electronic Resource
    Electronic Resource
    Role of gibberellins in parthenocarpic fruit development induced by the genetic system pat-3/pat-4 in tomato (2001)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 111 (2001), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The role of gibberellins (GAs) in the induction of parthenocarpic fruit-set and growth by the pat-3/pat-4 genetic system in tomato (Lycopersicon esculentum Mill.) was investigated using wild type (WT; Cuarenteno) and a near-isogenic line derived from the German line RP75/59 (the source of pat-3/pat-4 parthenocarpy). Unpollinated WT ovaries degenerated but GA3 application induced parthenocarpic fruit growth. On the contrary, parthenocarpic growth of pat-3/pat-4 fruits, which occurs in the absence of pollination and hormone treatment, was not affected by applied GA3. Unpollinated pat-3/pat-4 fruit growth was negated by paclobutrazol, an inhibitor of ent-kaurene oxidase, and this inhibitory effect was negated by GA3. The quantification of the main GAs of the early 13-hydroxylation pathway (GA1, GA8, GA19, GA20, GA29 and GA44) in unpollinated ovaries at 3 developmental stages (flower bud, FB; pre-anthesis, PR; and anthesis, AN), by gas chromatography-selected ion monitoring, showed that the concentration of most of them was higher in pat-3/pat-4 than in WT ovaries at PR and AN stages. The concentration of GA1, suggested previously to be the active GA in tomate, was 2–4 times higher. Unpollinated pat-3/pat-4 ovaries at FB, PR and AN stages also contained relatively high amounts (5–12 ng g−1) of GA3, a GA found at less than 0.5 ng g−1 in WT ovaries. It is concluded that the mutations pat-3/pat-4 may induce natural facultative parthenocarpy capacity in tomato by increasing the concentration of GA1 and GA3 in the ovaries before pollination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2001.1110416.x
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  • 10
    Electronic Resource
    Electronic Resource
    Light regulation of gibberellin A1 content and expression of genes coding for GA 20-oxidase and GA 3β-hydroxylase in etiolated pea seedlings (2000)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 108 (2000), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: White light (WL) inhibited the stem elongation of etiolated pea (Pisum sativum L.) seedlings and the inhibition was partially reversed by the application of gibberellin A1 (GA1), the active GA in shoot growth. The amount of GA1 in the apical shoot was reduced to about 25% after 2 h of WL, and to a trace level after 4 h. The effect of light on GA1 content was reversed when the plants were transferred again to the dark after 6 h of WL. The effect of light on the expression of GA 20-oxidase and GA 3β-hydroxylase genes, coding for the last steps of GA1 biosynthesis, was also investigated. Contrary to expectations, the amounts of GA 20-oxidase and GA 3β-hydroxylase transcripts increased in the entire apical shoot of WL-irradiated seedlings, and this increase was negated in seedlings treated with GA1 before WL irradiation, probably as a result of negative feed-back regulation. The effect of WL on GA 20-oxidase transcripts was mainly localized in the apex (hook) whereas the effect on GA 3β-hydroxylase transcripts was mainly localized in the subapical tissues. Red and far-red light also enhanced the GA 20-oxidase transcript level, but not that of GA 3β-hydroxylase, suggesting that different photoreceptors are involved in the regulation of these genes by WL. The results presented indicate that the inhibition of stem elongation by light is due, at least partially, to a decrease of GA1 content by a still unknown mechanism. The increase of GA8 upon WL irradiation raises the possibility that an inactivation activity may be involved in the control of the content of GA1 by light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2000.100216.x
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