STUDIES ON WHEAT PLANTS USING C14 COMPOUNDS: VIII. FORMATION OF AMYLOSE AND AMYLOPECTIN IN THE WHEAT KERNEL

1958 ◽  
Vol 36 (9) ◽  
pp. 985-991 ◽  
Author(s):  
W. B. McConnell ◽  
A. K. Mitra ◽  
A. S. Perlin
Keyword(s):  
Specific Activity ◽  
Wheat Starch ◽  
Field Conditions ◽  
Conversion Process ◽  
Straight Chain ◽  
Active Growth ◽  
Carbon 14 ◽  
Wheat Kernel ◽  
Tracer Techniques ◽  
A Minor

Tracer techniques have been used to examine the pattern by which the straight-chain and branched components of wheat starch are laid down in the maturing kernel. The starches were isolated from kernels of wheat plants to which had been administered glucose-1-C14, acetate-1-C14, or acetate-2-C14 at different periods of active growth under field conditions. Fractionation of the starches gave amylose and amylopectin and, in addition, a minor fraction of amylopectin, all labelled with carbon-14. Notable differences were found in the specific activity of these starch fractions, and in the distribution of carbon-14 within the monomeric units of samples labelled via glucose-1-C14. These findings indicate that the process of starch deposition in the kernel is not extensively reversible. Amylopectin appears to be formed from amylose, in agreement with current views, and it is suggested that the minor amylopectin component is an intermediate in this conversion process.

STUDIES ON WHEAT PLANTS USING C14 COMPOUNDS: VIII. FORMATION OF AMYLOSE AND AMYLOPECTIN IN THE WHEAT KERNEL

1958 ◽  
Vol 36 (1) ◽  
pp. 985-991 ◽  
Author(s):  
W. B. McConnell ◽  
A. K. Mitra ◽  
A. S. Perlin
Keyword(s):  
Specific Activity ◽  
Wheat Starch ◽  
Field Conditions ◽  
Conversion Process ◽  
Straight Chain ◽  
Active Growth ◽  
Carbon 14 ◽  
Wheat Kernel ◽  
Tracer Techniques ◽  
A Minor

Tracer techniques have been used to examine the pattern by which the straight-chain and branched components of wheat starch are laid down in the maturing kernel. The starches were isolated from kernels of wheat plants to which had been administered glucose-1-C14, acetate-1-C14, or acetate-2-C14 at different periods of active growth under field conditions. Fractionation of the starches gave amylose and amylopectin and, in addition, a minor fraction of amylopectin, all labelled with carbon-14. Notable differences were found in the specific activity of these starch fractions, and in the distribution of carbon-14 within the monomeric units of samples labelled via glucose-1-C14. These findings indicate that the process of starch deposition in the kernel is not extensively reversible. Amylopectin appears to be formed from amylose, in agreement with current views, and it is suggested that the minor amylopectin component is an intermediate in this conversion process.

RADIOCHEMICAL EVIDENCE FOR HETEROGENEITY IN WHEAT STARCH

1958 ◽  
Vol 36 (5) ◽  
pp. 810-813 ◽  
Author(s):  
A. S. Perlin
Keyword(s):  
Specific Activity ◽  
Wheat Starch ◽  
Carbon 14 ◽  
Minor Fraction ◽  
Wheat Starches ◽  
Leaching Procedure

Wheat starches labeled with carbon-14 have been fractionated by a novel leaching procedure to give amylose, amylopectin, and a highly-branched minor fraction designated "amylopectin C". Marked differences in the specific activity of the fractions are found. Subfractionation of amylopectin also gives products of varying specific activity. These findings provide radiochemical evidence for heterogeneity in wheat starch.

The persistent Toxicity under standardised field Conditions of Pyrethrum, DDT and “Gammexane” against Pests of stored Food

1949 ◽  
Vol 40 (1) ◽  
pp. 135-148 ◽  
Author(s):  
A. F. O'Farrell ◽  
B. M. Jones ◽  
G. A. Brett
Keyword(s):  
Field Conditions ◽  
Minor Factor ◽  
A Minor

The persistent toxicity of films of pyrethrum in P31 oil may endure on suitable surfaces under warehouse conditions for much longer periods than hitherto supposed, but unexplained fluctuations in toxicity may occur.Within the range 0·8 per cent. to 1·3 per cent. total pyrethrins, the pyrethrum content appears to be only a minor factor in determining the persistent toxicity of such films.The nature of the surface sprayed is of great importance in determining the persistent toxicity of pyrethrum films in P31 oil, which is negligible on concrete and increases steadily through the following list of surfaces—brick, heavy hessian, light hessian, jute, cotton, and wood; the last-mentioned two being particularly good substrates.Residual deposits of DDT or “ Gammexane ” derived from kerosene sprays are of little use on concrete, but appear otherwise little affected by the nature of the surface treated; they give a uniform degree of persistent toxicity on the various surfaces listed.

RyR1 exhibits lower gain of CICR activity than RyR3 in the SR: evidence for selective stabilization of RyR1 channel

2004 ◽  
Vol 287 (1) ◽  
pp. C36-C45 ◽  
Author(s):  
Takashi Murayama ◽  
Yasuo Ogawa
Keyword(s):  
Binding Sites ◽  
Skeletal Muscles ◽  
Specific Activity ◽  
Adenine Nucleotides ◽  
Minor Effect ◽  
Mammalian Skeletal Muscle ◽  
Selective Stabilization ◽  
Underlying Mechanisms ◽  
A Minor

We showed that frog α-ryanodine receptor (α-RyR) had a lower gain of Ca2+-induced Ca2+ release (CICR) activity than β-RyR in sarcoplasmic reticulum (SR) vesicles, indicating selective “stabilization” of the former isoform (Murayama T and Ogawa Y. J Biol Chem 276: 2953–2960, 2001). To know whether this is also the case with mammalian RyR1, we determined [3H]ryanodine binding of RyR1 and RyR3 in bovine diaphragm SR vesicles. The value of [3H]ryanodine binding (B) was normalized by the number of maximal binding sites (Bmax), whereby the specific activity of each isoform was expressed. This B/Bmax expression demonstrated that ryanodine binding of individual channels for RyR1 was <15% that for RyR3. Responses to Ca2+, Mg2+, adenine nucleotides, and caffeine were not substantially different between in situ and purified isoforms. These results suggest that the gain of CICR activity of RyR1 is markedly lower than that of RyR3 in mammalian skeletal muscle, indicating selective stabilization of RyR1 as is true of frog α-RyR. The stabilization was partly eliminated by FK506 and partly by solubilization of the vesicles with CHAPS, each of which was additive to the other. In contrast, high salt, which greatly enhances [3H]ryanodine binding, caused only a minor effect on the stabilization of RyR1. None of the T-tubule components, coexisting RyR3, or calmodulin was the cause. The CHAPS-sensitive intra- and intermolecular interactions that are common between mammalian and frog skeletal muscles and the isoform-specific inhibition by FKBP12, which is characteristic of mammals, are likely to be the underlying mechanisms.

Role of glucose in corneal metabolism

1985 ◽  
Vol 249 (5) ◽  
pp. C409-C416 ◽  
Author(s):  
R. S. Thies ◽  
L. J. Mandel
Keyword(s):  
Oxygen Consumption ◽  
Steady State ◽  
Specific Activity ◽  
Krebs Cycle ◽  
Lactate Production ◽  
Minor Component ◽  
Acid Oxidation ◽  
Endogenous Fatty Acid ◽  
Nonsteady State ◽  
A Minor

Glucose catabolism by glycolysis and the Krebs cycle was examined in the isolated rabbit cornea incubated with [6-14C]glucose. The production of [14C]lactate and 14CO2 from this substrate provided minimal values for the fluxes through these pathways since the tissue was in metabolic steady state but not isotopic steady state during the 40-min incubation. The specific activity of lactate under these conditions was one-third of that for [6-14C]glucose, and label dilution by exchange with unlabeled alanine was minimal, suggesting that glycogen degradation was primarily responsible for this dilution of label in the Embden-Meyerhof pathway. In addition, considerable label accumulation was found in glutamate and aspartate. Calculations revealed that these endogenous amino acid pools were not isotopically equilibrated after the incubation period, suggesting that they were responsible for the isotopic nonsteady state by exchange dilution through transaminase reactions with labeled intermediates. An estimate of glucose oxidation by the Krebs cycle, which was corrected for label dilution by exchange, indicated that glucose could account for most of the measured corneal oxygen consumption that was coupled to oxidative phosphorylation. A minor component of this respiration could not be accounted for by glucose or glycogen oxidation. Additional experiments suggested that endogenous fatty acid oxidation was probably also active under these conditions. Finally, reciprocal changes in plasma membrane Na+-K+-ATPase activity induced by ouabain and nystatin were found to concomitantly alter oxygen consumption rates and [14C]lactate production from [6-14C]glucose. These results demonstrated the capacity for regulating glycolysis and the Krebs cycle in response to changing energy demands in the cornea.

Wind-Evoked Escape Running of the cricket Gryllus Bimaculatus: I. Behavioural Analysis

1992 ◽  
Vol 171 (1) ◽  
pp. 189-214 ◽  
Author(s):  
HERIBERT GRAS ◽  
MICHAEL HÖRNER
Keyword(s):  
Action Potentials ◽  
Specific Activity ◽  
Angular Speed ◽  
Continuous Sequence ◽  
Behavioural Analysis ◽  
Prothoracic Ganglion ◽  
Short Run ◽  
Stimulus Source ◽  
A Minor ◽  
Spontaneous Walking

Spontaneous walking and escape running in response to wind puffs directed to the abdominal cerci were quantitatively studied in tethered walking crickets. 1. An apparatus for optically recording rotations of an air-supported sphere was developed to measure the intended locomotion of insects with high linear and temporal resolution but without mechanically imposed bias. 2. During spontaneous locomotion without sensory cues for orientation, alternate pauses of 0.35–2.2s and walking phases of 0.5–6s resulted in a highly variable pattern of locomotion on a meandering path. 3. A single air puff to one or both of the wind-sensitive cerci evoked a short run, whereas a continuous sequence of puffs caused sustained escape running with a tendency to turn away from the stimulus source. Escape running was characterized by a series of stereotyped running bouts and pauses, both significantly shorter than those recorded during spontaneous locomotion. 4. Forward speed and angular speed of escape running correlated linearly with the wind puff frequency between 5 and 10Hz. This was caused by a shortening of the standing phases, while the durations of the running bouts were constant. The reflex-like running bouts and the pattern of escape running were largely independent of the duty cycle of the wind puff series and the wind speed. Neither individual steps nor running bouts were synchronized with the stimulus pattern. 5. The behavioural modes of spontaneous walking and escape running were maintained with a minor reduction in general activity in partly dissected specimens during intracellular recording in the prothoracic ganglion. Each impaled local interneurone with locomotion-related activity generated action potentials in the actual step rhythm of walking and running bouts, but did not show specific activity during escape running. Some of these local neurones, however, showed modulations of spike frequency before or during intended turns and may participate in the coordination of the prothoracic legs.

High Performance Liquid Chromatography Coupled with Radioactivity Detection: A Powerful Tool for Determining Drug Metabolite Profiles in Biological Fluids

1986 ◽  
Vol 41 (1-2) ◽  
pp. 115-125 ◽  
Author(s):  
K.-O. Vollmer ◽  
W. Klemisch ◽  
A. von Hodenberg
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Biological Fluids ◽  
Gradient Elution ◽  
Reversed Phase ◽  
Isolation And Purification ◽  
Carbon 14 ◽  
Tracer Techniques ◽  
Metabolite Profiles

Abstract High performance liquid chromatography coupled with continuous radioactivity detection rep­resents an advancement in drug metabolism research. Using radioactive substances labelled in biologically stable positions, all metabolites can be specifically detected by radioactivity measure­ment. Thus no clean-up of biological fluids is required prior to HPLC. This can prevent artefact formation from unstable metabolites, reduces recovery problems and facilitates quantitation. Separation of highly polar and unpolar metabolites is possible in a single chromatographic run using gradient elution and reversed phase materials. This technique is also well-suited for prepara­tive isolation and purification of metabolites for subsequent structure elucidation. Various metabolite profiles of drugs labelled with carbon-14 or tritium are shown. Metabolites of the following drugs are presented: norfenefrine, etozolin, thymoxamine, naloxone, and levobunolol. We review the general methodology and report our experience with this technique. In principle, this technique may be useful for all biological systems in which tracer techniques are applied.

THE METABOLISM OF VALERATE-2-C14 BY UREDOSPORES OF WHEAT STEM RUST

1963 ◽  
Vol 41 (1) ◽  
pp. 1-7 ◽  
Author(s):  
H. Reisener ◽  
A. J. Finlayson ◽  
W. B. McConnell
Keyword(s):  
Carbon Dioxide ◽  
Glutamic Acid ◽  
Specific Activity ◽  
Tricarboxylic Acid Cycle ◽  
High Specific Activity ◽  
Water Soluble ◽  
Buffer Solution ◽  
Wheat Stem Rust ◽  
Carbon 14 ◽  
Water Soluble Extract

When uredospores of Puccinia graminis var. tritici race 15B were shaken in a medium containing M/30 phosphate buffer, pH 6.2, and valerate-2-C14, about 88% of the radioactivity was removed from the buffer solution in a period of 3 hours. About 40% of the carbon-14 taken from the buffer was found in a water-soluble extract of the spores and about 15% was respired as carbon dioxide. The result is compared with an earlier report that carbon 1 of valerate is more extensively released as carbon dioxide and less extensively incorporated into spore components. Glutamic acid, glutamine, γ-aminobutyric acid, and alanine of high specific activity were isolated. It was estimated from partial degradation that more than one-half of the carbon-14 of glutamic acid occurred in position 4 and that carbon 5 was very weakly labelled. Citric acid was also of high specific activity and was labelled predominantly in the internal carbons.It is concluded that respiring rust spores utilize externally supplied valerate by β-oxidation, which releases carbons 1 and 2 in a form which is metabolized as acetate by the tricarboxylic acid cycle.

scholarly journals Enhanced expression of glucose-6-phosphate dehydrogenase in human cells sustaining oxidative stress

1997 ◽  
Vol 323 (3) ◽  
pp. 801-806 ◽  
Author(s):  
Matilde V. URSINI ◽  
Angelina PARRELLA ◽  
Graziella ROSA ◽  
Salvatore SALZANO ◽  
Giuseppe MARTINI
Keyword(s):  
Oxidative Stress ◽  
Mammalian Cells ◽  
Specific Activity ◽  
Redox Status ◽  
Enzyme Synthesis ◽  
Oxygen Intermediates ◽  
New Information ◽  
Enhanced Expression ◽  
A Minor ◽  
Glucose 6 Phosphate Dehydrogenase

Recent reports have demonstrated that glucose-6-phosphate dehydrogenase (G6PD) activity in mammalian cells is necessary in order to ensure cell survival when damage is produced by reactive oxygen intermediates. In this paper we demonstrate that oxidative stress, caused by agents acting at different steps in the biochemical pathway controlling the intracellular redox status, determines the increase in G6PD-specific activity in human cell lines of different tissue origins. The intracellular level of G6PD-specific mRNA also increases, with kinetics compatible with the induction of new enzyme synthesis. We carried out experiments in which cells were exposed to oxidative stress in the presence of inhibitors of protein or RNA synthesis. These demonstrated that increased G6PD expression is mainly due to an increased rate of transcription, with a minor but significant contribution of regulatory mechanisms acting at post-transcriptional levels. These results provide new information on the defence systems that eukaryotic cells possess in order to prevent damage caused by potentially harmful oxygen derivatives.

STUDIES ON WHEAT PLANTS USING CARBON-14 LABELLED COMPOUNDS: X. THE INCORPORATION OF GLUTAMIC ACID-l-C14

1959 ◽  
Vol 37 (1) ◽  
pp. 933-936 ◽  
Author(s):  
W. B. McConnell
Keyword(s):  
Amino Acids ◽  
Glutamic Acid ◽  
Specific Activity ◽  
Wheat Plant ◽  
Protein Fractions ◽  
Appreciable Amount ◽  
Kernel Development ◽  
Carbon 14

Glutamic acid-1-C14 was injected into the top internode of wheat stems at a stage of growth when kernel development was rapid (71 days after seeding). The plants were harvested 31 days later when they had matured and the incorporation of carbon-14 studied. About one-third of the carbon-14 administered was found in the upper portions of the mature plants, much of the remaining radioactivity having apparently been respired. About 85% of the carbon-14 recovered was found in the kernel. The protein fractions of these were most radioactive, but an appreciable amount of carbon-14 also appeared in the starch. Glutamic acid had the highest specific activity of the amino acids isolated from the gluten, but proline and arginine were also strongly labelled. Since these three amino acids were labelled predominantly in carbon-1 their close metabolic relationship in the wheat plant seems probable.

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