Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Gibberellin metabolism in excised lettuce hypocotyls: Response to GA9 and the conversion of [3H]GA9 (1978)
    Springer
    Planta 140 (1978), S. 143-150 
    Details
    ISSN: 1432-2048
    Keywords: Cell elongation ; Gibberellins ; Lactuca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Elongation growth and gibberellin (GA9) metabolism in excised hypocotyls of lettuce (Lactuca sativa L. cv. Arctic) were investigated. Exogenously supplied GA9 stimulates elongation of hypocotyl sections and this response is intermediate between that elicited by GA1 or GA20 and GA4/7 mixture. Although uptake of radioactivity from [3H]GA9 increases with time, this gibberellin does not accumulate in the tissue but is rapidly converted to a compound with HPLC properties resembling those of [3H]GA20. After 2 h incubation in [3H]GA9, the presumptive GA20 represents 90% of the acidic ethyl acetate-soluble radioactivity in the tissue. Radioactivity is also associated with an acidic butanol-soluble fraction containing two components resolvable by HVE. The major component is similar in electrophoretic properties to a GA-glucosyl ether while the other compares to a GA-glucosyl ester. Conversion of [3H]GA9 to its [3H]GA20-like metabolite is reduced by addition of carrier GA9 or GA4/7 at concentrations as low as 1 μM, while GA1, GA3 and L-proline are without effect. Formation of the GA20-like compound can be blocked by the addition of 2,2′-dipyridyl, and this inhibitory effect of dipyridyl can be reversed by addition of Fe2+. At 200 μM dipyridyl, elongation growth as well as [3H]GA9 metabolism are reduced by 80%. The relationship of the metabolism of GA9 to the growth response is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384913
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The role of the endoplasmic reticulum in the synthesis and transport of α-amylase in barley aleurone layers (1982)
    Springer
    Planta 156 (1982), S. 421-432 
    Details
    ISSN: 1432-2048
    Keywords: Aleurone ; α-Amylase ; Endoplasmic reticulum ; Gibberellin and enzyme formation ; Hordeum (α-amylase in aleurone)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The subcellular site of α-amylase (EC 1.6.2.1) synthesis and transport was studied in barley aleurone layers incubated in the presence or absence of gibberellic acid (GA3). Using [35S]methionine as a marker, the site of amino-acid incorporation into organelles isolated from aleurone layers incubated with and without GA3 was determined following purification by isopycnic sucrose-density-gradient centrifugation. Incorporation of radioactivity into trichloroacetic-acid-insoluble proteins was greatest in those fractions exhibiting activity of an endoplasmic reticulum (ER) marker enzyme. Further fractionation of densitygradient fractions by sodium-dodecyl-sulfate polyacrylamide-gel electrophoresis showed that a major portion of the radioactivity in the ER fractions was present in a protein co-migrating with marker α-amylase. This protein was identified as authentic α-amylase by immunoadsorbent chromatography and affinity chromatography. The newly synthesized α-amylase associated with the ER was shown to be sequenstered within the lumen of the ER by experiments which showed that the enzyme was resistant to proteolytic degradation. The labelled α-amylase sequestered in the ER can be chased from this organelle when tissue is incubated in unlabelled methionine following a 1-h pulse of labelled methionine. The isoenzymic forms of α-amylase found in tissue homogenates and incubation media of aleurone layers incubated with and without GA3 were characterized after chromatography on diethylaminoethyl cellulose. In homogenates of GA3-treated aleurone layers, five peaks of α-amylase activity were detected, while in homogenates of aleurone layers incubated with-out GA3 only three peaks of activity were found. In incubation media, four isoenzymes were found after GA3 treatment and two were found after incubation without GA3. We conclude that at least five α-amylase isoenzymes are synthesized by the ER of barley aleurone layers and that this membrane system is involved in the sequestration and transport of four of these isoenzymes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393313
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    The role of acidification in gibberellic acid- and fusicoccin-induced elongation growth of lettuce hypocotyl sections (1978)
    Springer
    Planta 142 (1978), S. 135-145 
    Details
    ISSN: 1432-2048
    Keywords: Acid growth ; Cell elongation ; Gibberellin ; Fusicoccin ; Lactuca ; Hordeum ; Potasium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The roles of gibberellic acid (GA3) and fusicoccin (FC) in the elongation growth and acidification of the medium by excised hypocotyl sections of lettuce (Lactuca sativa L.) were investigated. Hypocotyl sections incubated in buffer without GA3 elongate optimally at pH 4.0–4.25 while sections incubated with GA3 show the same growth between pH 4.25 and 6.0. Preincubation of sections at pH 6.0 for 6 h does not affect the subsequent elongation response to acidic medium (pH 4.25); however, the sections become refractory to further acid treatment after their initial burst of growth in response to pH 4.25. Sections made refractory to acid are responsive to GA3 application, however, and the rate of growth in response to GA3 of sections pretreated for 6 h at pH 4.25 is 85% of that of sections pretreated at pH 6.0. Although preincubation of sections for 48 h in medium at pH 6.0 abolishes the GA3 response, it does not affect the response to buffer at pH 4.25. FC stimulates elongation growth in letuce hypocotyls at an optimal concentration of 1 μM, and pretreatment of sections at pH 4.25 does not affect this elongation response. Although both GA3 and FC increase elongation of the section, neither causes appreciable acidification of the medium. Addition of KCl or NaCl to FC-treated sections causes rapid medium acidification but addition of salts to GA3-treated tissue does not cause acidification. Abrasion of the hypocotyl to remove the cuticle does not enhance acidification of the medium by the sections nor deos it affect elongation of the sections in response to GA3 or FC. Medium acidification by the sections is not a passive process since it is abolished both by low temperature (2° C) and metabolic inhibitors (carbonyl cyanide-m-chlorophenyl-hydrazone, azide). The acidification of the medium by barley (Hordeum vulgare L.) roots in response to FC is also dependent on the presence of KCl. We conclude that the acid-growth hypothesis does not explain GA3- or FC-induced elongation in lettuce hypocotyls.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388204
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The isolation of endoplasmic reticulum from barley aleurone layers (1980)
    Springer
    Planta 150 (1980), S. 58-69 
    Details
    ISSN: 1432-2048
    Keywords: Aleurone ; α-Amylase ; Endoplasmic reticulum ; Hordeum ; Organelle isolation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Techniques for the isolation and purification of endoplasmic reticulum (ER) from aleurone layers of barley (Hordeum vulgare L.) were assessed. Neither differential centrifugation nor density gradient centrifugation of a homogenate separate the ER or other organelles of this tissue from the lipidcontaining spherosomes. Isopycnic sucrose gradient centrifugation of organelles first purified by molecular sieve chromatography on Sepharose 4B, however, results in separation of the organelles based on their differing buoyant densities. Manipulation of the magnesium concentration of the isolation media and density-gradient solutions affords isolation of ER at a density of 1.13–1.14 g cc-1 and 1.17–1.18 g cc-1. Electron microscopy shows that the membranes sedimenting at 1.13–1.14 g cc-1 are devoid of ribosomes and are characteristic of smooth ER, while those sedimenting at 1.17–1.18 g cc-1 are studded with ribosomes and have the features of rough ER. Endoplasmic reticulum isolated by isopycnic density gradient centrifugation can be further purified by rate-zonal centrifugation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385616
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Quantitative and qualitative changes in the endoplasmic reticulum of barley aleurone layers (1980)
    Springer
    Planta 150 (1980), S. 70-81 
    Details
    ISSN: 1432-2048
    Keywords: Aleurone ; α-Amylase ; Endoplasmic reticulum ; Gibberellin ; Hordeum ; Organelle isolation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in the level of the endoplasmicreticulum (ER) marker enzyme cytochrome-c reductase (EC 1.6.2.1) were followed with time of imbibition of de-embryonated half-seeds of barley (Hordeum vulgare L.) and the subsequent incubation of their aleurone layers in gibberellic acid (GA3) and H2O. During imbibition there is an increase in the level of cytochrome-c-reductase activity and in the amount of 280-nm absorbance associated with this enzyme. When aleurone layers are incubated for a further 42 h in water, there is a doubling of the cytochrome-c-reductase activity. In GA3, the activity of cytochrome-c reductase reaches a maximum at 24 h of incubation and thereafter falls to below 70% of its level at the beginning of the incubation period. Changes in the cytochrome-c-reductase activity correlate with changes in the fine structure of the aleurone cell. The ER isolated in low Mg2+ from aleurone layers incubated in buffer for up to 18 h has buoyant density of 1.13–1.14 g cc-1 while that from layers incubated in GA3 for 7.5–18 h has a density of 1.11–1.12 g cc-1. The α-amylase (EC3.2.1.1) isolated with the organelle fraction by Sepharose gel filtration is associated with the ER on isopycnic and rate-zonal density gradients, and its activity can be enhanced by Triton X-100. The soluble α-amylase fraction from Separose-4B columns, on the other hand, is not Triton-activated but is acid-labile. Acid phosphatase (EC3.1.3.2) is distributed in at least three peaks on isopycnic gradients. In low Mg2+ the second peak of activity has a density of 1.12 g cc-1 in GA3-treated tissue and 1.13–1.14 g cc-1 in H2O-treated tissue. With high-Mg2+ buffers, this peak of phosphatase activity disappears. Acid-phosphatase activity is not enhanced by Triton X-100 nor is it acid-labile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385617
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Calcium and gibberellin-induced elongation of lettuce hypocotyl sections (1981)
    Springer
    Planta 152 (1981), S. 450-456 
    Details
    ISSN: 1432-2048
    Keywords: Calcium ; Cell elongation ; Gibberellin ; Lactuca ; pH and growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between calcium ions and gibberellic acid (GA3)-induced growth in the excised hypocotyl of lettuce (Lactuca sativa L.) was investigated. The short-term kinetics of growth responses were measured using a linear displacement transducer. Test solutions were added either as drops to the filter paper on which the hypocotyl stood (“non-flow-past”) or by switching solution flowing past the base of hypocotyl (“flow-past”), resulting in differences in growth behavior. Drops of CaCl2 added at a high concentration (10 mM) inhibited growth within a few minutes. This inhibition was reversed by ethylenediaminetetraacetic acid (EDTA). Drops of EDTA or ethyleneglycol-bis(2-aminoethylether)-tetraacetic acid caused a rapid increase in growth rate. Growth induced by EDTA was not further promoted by GA3. A continuous H2O flow resulted in growth rates comparable to those in response to GA3. Addition of CaCl2 to the flow-past medium inhibited growth and this inhibition was reversed by a decrease in CaCl2 concentration. The growth rate was found to be a function of CaCl2 concentration. When a constant CaCl2 concentration was maintained by the flow-past medium, a shift in pH from 5.5 to 4.25 had no obvious effect on hypocotyl elongation. Gibberellic acid was found to reverse the inhibitory effect of CaCl2, causing an increase in growth rate similar to that found previously when GA3 was added to hypocotyls grown in H2O under non-flow-past conditions. We propose that gibberellin controls extension growth in lettuce hypocotyl sections by regulating the uptake of Ca2+ by the hypocotyl cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385362
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Cell elongation and cell division in elongating lettuce hypocotyl sections (1977)
    Springer
    Planta 135 (1977), S. 249-255 
    Details
    ISSN: 1432-2048
    Keywords: Cell division ; Cell elongation ; Gibberellin ; Lactuca ; Potassium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The roles of cell division and cell elongation in the growth of sections excised from hypocotyls of lettuce (Lactuca sativa L. cv. Arctic) were investigated. Elongation of sections incubated in the light is inhibited compared to dark-grown sections and this inhibition is reversed by gibberellic acid (GA3). The elongation of both dark-grown and GA3-treated, light-grown sections can be enhanced by 10mM KCl. Under all conditions of incubation, elongation growth is greatest in the uppermost quarter of the hypocotyl section while the basal quarter does not elongate. In darkness the two apical segments of sections marked into four equal parts grow at the same rate, while in light, growth of the apical segment exceeds that of the second segment. Cell division in cortical or epidermal cells, as measured by mitotic index or cell number, is not affected by illumination conditions nor by GA3 or KCl treatments. Although γ-irradiation and FUDR pretreatment eliminate or cause a marked reduction in cell division in the excised hypocotyl, sections from seeds irradiated with γ-rays or incubated in 5-fluorodeoxyuridine elongate in response to GA3 and KCl treatment as do sections from non-pretreated controls. Therefore, since neither GA3 nor darkness affect celldivision activity and since treatments which eliminate or significantly reduce cell division do not affect growth, we conclude that the effect of GA3 and darkness in this material is to increase cell elongation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384897
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Calcium regulation of the secretion of α-amylase isoenzymes and other proteins from barley aleurone layers (1983)
    Springer
    Planta 158 (1983), S. 1-9 
    Details
    ISSN: 1432-2048
    Keywords: Aleurone ; α-Amylase ; Calcium and enzyme secretion ; Enzyme secretion ; Gibberellin ; Hordeum (enzyme secretion)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of calcium on the secretion of α-amylase (EC 3.2.1.1) and other hydrolases from aleurone layers of barley (Hordeum vulgare L. cv. Himalaya) was studied. Withdrawal of Ca2+ from the incubation medium of aleurone layers preincubated in 5 μM gibberellic acid (GA3) and 5 mM CaCl2 results in a 70–80% reduction in the secretion of α-amylase activity to the incubation medium. Agar-gel electrophoresis shows that the reduction in α-amylase activity following Ca2+ withdrawal is correlated with the disappearance of group B isoenzymes from the incubation medium. The secretion of isoenzymes of group A is unaffected by Ca2+. The addition of Ca2+ stimulates the secretion of group-B isoenzymes but has no measurable effect on either the α-amylase activity or the isoenzyme pattern of aleurone-layer extracts. Pulse-labelling experiments with [35S]methionine show that Ca2+ withdrawal results in a reduction in the secretion of labelled polypeptides into the incubation medium. Immunochemical studies also show that, in the absence of Ca2+, α-amylase isoenzymes of group B are not secreted into the incubation medium. In addition to its effect on α-amylase, Ca2+ influences the secretion of other proteins including several acid hydrolases. The secretion of these other proteins shows the same dependence on Ca2+ concentration as does that of α-amylase. Other cations can promote the secretion of α-amylase to less and varying extents. Strontium is 85% as effective as Ca2+ while Ba2+ is only 10% as effective. We conclude that Ca2+ regulates the secretion of enzymes and other proteins from the aleurone layer of barley.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00395396
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...