Gibberellic Acid and Rna Synthesis in Barley Aleurone Layers: Metabolism of rRNA and tRNA and of RNA Containing Polyadenylic Acid Sequences

1974 ◽  
Vol 1 (3) ◽  
pp. 343 ◽  
Author(s):  
JV Jacobsen ◽  
JA Zwar
Keyword(s):  
Gibberellic Acid ◽  
Rrna Synthesis ◽  
Molecular Weights ◽  
Polyadenylic Acid ◽  
Major Species ◽  
Wide Range ◽  
Trna Species ◽  
Barley Aleurone ◽  
Regulation Of Synthesis ◽  
Amylase Induction

RNA containing polyadenylic acid sequences [poly(A)-RNA] was detected in and isolated from barley aleurone layers. Gibberellic acid (GA3) stimulated the synthesis of this RNA by about 70% over a 16-h period during which amylase induction occurred. The poly(A)-RNA was polydisperse on polyacrylamide gels and the effect of GA3 was to enhance synthesis of poly(A)-RNA species with a wide range of molecular weights. GA3 had no major effects on the synthesis of rRNA, 5 S RNA and tRNA species, and since it also had no effect on levels of total RNA in aleurone, it probably had no effect on RNA breakdown. Furthermore, rRNA synthesis could be essentially stopped with 5-fluorouracil with no effect on amylase synthesis, indicating that synthesis of new ribosomes was unnecessary for normal amylase induction. These results indicate that for amylase synthesis to occur in response to GA3, regulation of synthesis of mRNA but not that of the major species would appear to be necessary.

Gibberellic Acid-Induced Alpha -Amylase Synthesis in Wheat Aleurone Layers: a Distinction Between Site Saturation and Lag Times.

1982 ◽  
Vol 9 (6) ◽  
pp. 623 ◽  
Author(s):  
RA Gibson ◽  
LG Paleg
Keyword(s):  
Gibberellic Acid ◽  
Early Period ◽  
Sensitive Period ◽  
Saturation Time ◽  
Site Saturation ◽  
Wide Range ◽  
Lag Times ◽  
Amylase Induction ◽  
Aleurone Tissue ◽  
Time Required

We have examined a number of parameters relating to the gibberellic acid (GA3) requirement for the induction process which leads to the formation of �-amylase in wheat aleurone tissue. (1) Over a wide range of hormone concentrations, aleurone tissue was found to produce less �-amylase after hormone withdrawal by washing at a time soon after GA*3 application. (2) The approximate length of this washing-sensitive period was found to vary inversely to the applied GA*3 concentration. (3) Following this early period, a time was found when the response could not be lowered by this same washing procedure which had earlier lowered the response. (4) Separate experiments determined that these results could not be accounted for by variation in the lag/latent period, since the lag period was about the same for a wide range of GA*3 concentrations. To help explain these results we have suggested the term 'site saturation time' which is separate from but intimately involved with the lagllatent period. This term is defined as the time required for the saturation and activation of all sites which ultimately lead to the production of �-amylase. It is suggested that site saturation time must be taken into account when the early events of �-amylase induction are examined.

scholarly journals Recent Advancements in Polymer/Liposome Assembly for Drug Delivery: From Surface Modifications to Hybrid Vesicles

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1027
Author(s):  
Vincenzo De Leo ◽  
Francesco Milano ◽  
Angela Agostiano ◽  
Lucia Catucci
Keyword(s):  
Drug Delivery ◽  
First Generation ◽  
Phospholipid Bilayer ◽  
Bioactive Molecules ◽  
Systemic Delivery ◽  
Molecular Weights ◽  
Liposome Preparation ◽  
Wide Range ◽  
Liposome Surface

Liposomes are consolidated and attractive biomimetic nanocarriers widely used in the field of drug delivery. The structural versatility of liposomes has been exploited for the development of various carriers for the topical or systemic delivery of drugs and bioactive molecules, with the possibility of increasing their bioavailability and stability, and modulating and directing their release, while limiting the side effects at the same time. Nevertheless, first-generation vesicles suffer from some limitations including physical instability, short in vivo circulation lifetime, reduced payload, uncontrolled release properties, and low targeting abilities. Therefore, liposome preparation technology soon took advantage of the possibility of improving vesicle performance using both natural and synthetic polymers. Polymers can easily be synthesized in a controlled manner over a wide range of molecular weights and in a low dispersity range. Their properties are widely tunable and therefore allow the low chemical versatility typical of lipids to be overcome. Moreover, depending on their structure, polymers can be used to create a simple covering on the liposome surface or to intercalate in the phospholipid bilayer to give rise to real hybrid structures. This review illustrates the main strategies implemented in the field of polymer/liposome assembly for drug delivery, with a look at the most recent publications without neglecting basic concepts for a simple and complete understanding by the reader.

scholarly journals Sustainable Myrcene-Based Elastomers via a Convenient Anionic Polymerization

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 838
Author(s):  
David Hermann Lamparelli ◽  
Magdalena Maria Kleybolte ◽  
Malte Winnacker ◽  
Carmine Capacchione
Keyword(s):  
Anionic Polymerization ◽  
Sodium Hydride ◽  
Reactivity Ratios ◽  
Molecular Weights ◽  
Styrene Copolymers ◽  
Wide Range ◽  
Elastomeric Materials ◽  
Complete Study ◽  
Anionic Copolymerization ◽  
Trialkylaluminum Derivatives

Soluble heterocomplexes consisting of sodium hydride in combination with trialkylaluminum derivatives have been used as anionic initiating systems at 100 °C in toluene for convenient homo-, co- and ter-polymerization of myrcene with styrene and isoprene. In this way it has been possible to obtain elastomeric materials in a wide range of compositions with interesting thermal profiles and different polymeric architectures by simply modulating the alimentation feed and the (monomers)/(initiator systems) ratio. Especially, a complete study of the myrcene-styrene copolymers (PMS) was carried out, highlighting their tapered microstructures with high molecular weights (up to 159.8 KDa) and a single glass transition temperature. For PMS copolymer reactivity ratios, rmyr = 0.12 ± 0.003 and rsty = 3.18 ± 0.65 and rmyr = 0.10 ± 0.004 and rsty = 3.32 ± 0.68 were determined according to the Kelen–Tudos (KT) and extended Kelen–Tudos (exKT) methods, respectively. Finally, this study showed an easy accessible approach for the production of various elastomers by anionic copolymerization of renewable terpenes, such as myrcene, with commodities.

scholarly journals Analysis of the Impact on the Mechanical Properties of Modification of Oligohydroxyethers in Organic Solvent Solution with Rubbers

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 519
Author(s):  
Vitalii Bezgin ◽  
Agata Dudek ◽  
Adam Gnatowski
Keyword(s):  
Mechanical Properties ◽  
Scientific Paper ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Molecular Weights ◽  
Wide Range ◽  
Strength Tests ◽  
Materials Used ◽  
Styrene Butadiene ◽  
The Impact

This paper proposes and presents the chemical modification of linear hydroxyethers (LHE) with different molecular weights (380, 640, and 1830 g/mol) with the addition of three types of rubbers (polysulfide rubber (PSR), polychloroprene rubber (PCR), and styrene-butadiene rubber (SBR)). The main purpose of choosing this type of modification and the materials used was the possibility to use it in industrial settings. The modification process was conducted for a very wide range of modifier additions (rubber) per 100 g LHE. The materials obtained in the study were subjected to strength tests in order to determine the effect of the modification on functional properties. Mechanical properties of the modified materials were improved after the application of the modifier (rubber) to polyhydroxyether (up to certain modifier content). The most favorable changes in the tested materials were registered in the modification of LHE-1830 with PSR. In the case of LHE-380 and LHE-640 modified in cyclohexanol (CH) and chloroform (CF) solutions, an increase in the values of the tested properties was also obtained, but to a lesser extent than for LHE-1830. The largest changes were registered for LHE-1830 with PSR in CH solution: from 12.1 to 15.3 MPa for compressive strength tests, from 0.8 to 1.5 MPa for tensile testing, from 0.8 to 14.7 MPa for shear strength, and from 1% to 6.5% for the maximum elongation. The analysis of the available literature showed that the modification proposed by the authors has not yet been presented in any previous scientific paper.

Stress mRNA metabolism in canavanine-treated chicken embryo cells

1984 ◽  
Vol 4 (8) ◽  
pp. 1534-1541
Author(s):  
C N White ◽  
L E Hightower
Keyword(s):  
Steady State ◽  
Stress Proteins ◽  
Animal Cell ◽  
Stress Protein ◽  
High Rate ◽  
Rrna Synthesis ◽  
28S Rrna ◽  
Mrna Levels ◽  
Molecular Weights

Four major chicken stress mRNAs with apparent molecular weights of 1.2 X 10(6), 0.88 X 10(6), 0.59 X 10(6), and 0.25 X 10(6) to 0.28 X 10(6) were separated on acidic agarose-urea gels. Using cell-free translation, the coding assignments of these mRNAs were determined to be stress proteins with apparent molecular weights of 88,000, 71,000, 35,000, and 23,000. Despite high levels of translational activity in vivo and in vitro, no newly synthesized mRNA for the 23-kilodalton stress protein was detected on gels under conditions which readily allowed detection of other stress mRNAs, suggesting activation of a stored or incompletely processed mRNA. Cloned Drosophila heat shock genes were used to identify and measure changes in cellular levels of the two largest stress mRNAs. Synthesis of these mRNAs increased rapidly during the first hour of canavanine treatment and continued at a high rate for at least 7 h, with the mRNAs attaining new steady-state levels by ca. 3 h. Both of these inducible stress mRNAs had very short half-lives compared with other animal cell mRNAs. Using an approach-to-steady-state analysis, the half-lives were calculated to be 89 min for the mRNA encoding the 88-kilodalton stress protein and 46 min for the mRNA encoding the 71-kilodalton stress protein. Chicken 18S and 28S rRNA synthesis was inhibited, and actin mRNA levels measured with cloned cDNA encoding chicken beta-actin slowly declined in canavanine-treated cells.

Subunit studies of coupling factor 1 of bean chloroplasts

1976 ◽  
Vol 54 (5) ◽  
pp. 481-487 ◽  
Author(s):  
M. P. Silvanovich ◽  
R. D. Hill
Keyword(s):  
Amino Acid ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Coupling Factor ◽  
Leaf Extracts ◽  
Molecular Weights ◽  
Major Species ◽  
Chloroplast Coupling Factor ◽  
Coupling Factors

A bean chloroplast coupling factor (CF1) with latent Ca2+-dependent ATPase activity was studied. Immunodiffusion of bean (Phaseolus vulgaris) chloroplast and etioplast coupling factors and spinach coupling factor against antiserum to spinach coupling factor showed partial identity of the bean coupling factor with that of spinach. An immunoelectrophoretic comparison, under dissociating conditions, of bean leaf extracts and spinach extracts containing CF1 subunits (as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis) gave identical results for both extracts. At least six distinct polypeptide species were found. The major species had molecular weights of 42 000, 59 000 and 63 000 daltons. Amino acid analysis of electrophoretically purified bean CF1 gave results similar to those published for spinach CF1.

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