Nectar secretion in excised flowers. VI. Relationship of secretion to protein metabolism

1978 ◽  
Vol 56 (7) ◽  
pp. 833-842 ◽  
Author(s):  
R. W. Shuel ◽  
W. Tsao
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Indoleacetic Acid ◽  
Sugar Transport ◽  
Adsorptive Capacity ◽  
Total Protein Content ◽  
Nectar Secretion ◽  
Protein Gel ◽  
Relationship Of ◽  
Stimulation Of

The relationship of nectar secretion in snapdragon to protein metabolism, and the influence on both processes of indoleacetic acid (IAA) and to a lesser extent pollination, were both studied. Indoleacetic acid at 5 × 10−4 M appeared to initiate a reorganization in the nectary which led to the stimulation of growth and an early termination of secretion. Two hours after treatment began, incorporation of [14C]uracil into RNA was 60% higher than in controls. A twofold to threefold increase in protein synthesis from [14C]sucrose followed but with no increase and usually a reduction in total nectary protein, despite considerable enlargement of the nectary. These effects suggested a differential action of IAA on protein synthesis and an enhanced degradation of existing protein. Changes in RNA and protein gel electropherograms, and a lowering of the adsorptive capacity of protein in nectary homogenate for [14C]sucrose, were also noted. Actinomycin C, puromycin, and chloramphenicol, like IAA, strongly inhibited secretion but differed from IAA with respect to other effects. None stimulated nectary growth. Actinomycin inhibited synthesis of protein from [14C]sucrose. Puromycin and chloramphenicol increased the amount of protein synthesized from [14C]sucrose but reduced the total protein content. Changes in the nectary following pollination resembled those caused by IAA with respect to RNA and protein gel patterns, stimulation of growth, reduction in tissue protein concentration, and cessation of nectar secretion. It is possible, though not demonstrated, that termination of secretion by IAA and pollination was mediated by changes in proteins associated with sugar transport.

Stimulation of C14-histidine incorporation into protein of isolated diaphragm by nonutilized sugars

1960 ◽  
Vol 198 (1) ◽  
pp. 57-59 ◽  
Author(s):  
Ira G. Wool
Keyword(s):  
Protein Synthesis ◽  
Glucose Concentration ◽  
Protein Metabolism ◽  
Incubation Medium ◽  
Muscle Protein ◽  
Positive Influence ◽  
Effect Of Glucose ◽  
Stimulation Of

The effect of various sugars on protein synthesis was studied by measuring the incorporation of C14-histidine into the protein of the isolated diaphragm. In diaphragms from rats fasted 48 hours, histidine-2-C14 incorporation into muscle protein is directly proportional to the glucose concentration in the incubation medium over the range 0–600 mg %. The ability of other sugars to reproduce this effect of glucose on C14-histidine incorporation into diaphragm protein was tested. The following were found to be as effective as glucose: d-mannose; d-xylose; d-ribose; l-sorbose. The following were without effect: d-galactose; d-fructose; 3-methyl glucose; d-arabinose; l-arabinose; l-xylose. Only 2-deoxy-d-glucose was inhibitory. The results indicate that sugars not appreciably utilized by muscle (i.e. d-xylose, d-ribose and l-sorbose) can increase protein synthesis. The findings do not support the theory that the positive influence of carbohydrate on protein metabolism derives solely from its ability to increase the energy available for protein synthesis.

scholarly journals Regulation of protein metabolism by a physiological concentration of insulin in mouse soleus and extensor digitorum longus muscles. Effects of starvation and scald injury

1979 ◽  
Vol 184 (2) ◽  
pp. 323-330 ◽  
Author(s):  
K N Frayn ◽  
P F Maycock
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Extensor Digitorum Longus ◽  
Muscle Protein ◽  
Extensor Digitorum ◽  
Total Protein Content ◽  
Skin Thickness ◽  
Physiological Concentration ◽  
Scald Injury

1. Although high concentrations of insulin affect both synthesis and degradation of skeletal-muscle protein, it is not known to what extent these effects occur with physiological concentrations. The effects of a physiological concentration of insulin (100 mu units/ml) on muscle protein synthesis, measured with [3H]tyrosine, and on muscle protein degradation, measured by tyrosine release in the presence of cycloheximide, were studied in mouse soleus and extensor digitorum longus muscles in vitro. 2. Insulin significantly stimualated protein synthesis in both muscles, but an inhibition of degradation was seen only in the extensor digitorum longus. 3. Starvation for 24 h decreased the rate of protein synthesis and increased the rate of breakdown in the extensor digitorum longus. Sensitivity to insulin-stimulation of proteins synthesis in the soleus was increased by starvation. 4.;a 20%-surface-area full-skin-thickness dorsal scald injury produced a fall in total protein content in soleus and extensor digitorum muscles, maximal on the third day after injury. Soleus muscles 2 days after injury showed an impairment of protein synthesis; degradation was unaffected and neither synthesis nor degradation in vitro was significantly affected in the extensor digitorum longus. 5. The advantages and limitations of studies of protein metabolism in vitro are discussed.

scholarly journals Selectivity of the insulin-like actions of vanadate on glucose and protein metabolism in skeletal muscle

1985 ◽  
Vol 232 (1) ◽  
pp. 273-276 ◽  
Author(s):  
A S Clark ◽  
J M Fagan ◽  
W E Mitch
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Insulin Receptor ◽  
Glucose Uptake ◽  
Protein Metabolism ◽  
Glucose Oxidation ◽  
Glycogen Synthesis ◽  
Metabolic Responses ◽  
Receptor Phosphorylation ◽  
Stimulation Of

To determine if vanadate has insulin-like actions in skeletal muscle, we measured its effects on glucose and protein metabolism in epitrochlearis muscles of rats. Compared with insulin, vanadate increased glucose uptake, glycogen synthesis and glycolysis to a lesser degree, but caused a greater stimulation of lactate and glucose oxidation. Unlike insulin, vanadate did not change either protein synthesis or degradation. These different metabolic responses could be related to the different pattern of insulin-receptor phosphorylation caused by insulin and vanadate.

Nectar secretion in excised flowers. V. Effects of indoleacetic acid and sugar supply on distribution of [14C]sucrose in flower tissues and nectar

1978 ◽  
Vol 56 (6) ◽  
pp. 565-571 ◽  
Author(s):  
R. W. Shuel
Keyword(s):  
Indoleacetic Acid ◽  
Sugar Transport ◽  
Reducing Sugar ◽  
Secretory Process ◽  
Percentage Reduction ◽  
Nectar Secretion ◽  
Minimal Growth ◽  
Transport Distance ◽  
Sucrose Solutions ◽  
Secretory Tissue

Movement and distribution of [14C]sucrose was studied in snapdragon flowers cultured on sucrose solutions in relation to the timing and extent of the characteristic reduction of nectar yield by 1AA, the question of whether IAA acts in the nectary cells or by reducing sugar movement to the nectary, and competition for sugar between nectaries and other tissues.There was a 50% reduction in accumulated nectar yield in flowers treated with IAA within 18 h; thereafter, the capacity to secrete nectar was virtually abolished. Within 6 h, IAA caused a significant increase in the incorporation of 14C into protein. Most of the 14C activity lost to nectar in flowers treated with IAA was recovered in the ethanol-soluble materials and protein of the flowers. Radioactivity continued to accumulate in the secretory tissue after secretion had stopped. The percentage reduction in nectar by IAA was not diminished under conditions of minimal growth and sugar transport distance. It was concluded that IAA acts on the secretory process in the nectary cells rather than on movement of sugar to the nectary.The influence of differences in sugar supply appeared mainly in the distribution of 14C activity between peduncles and nectar: as sugar supply was increased, a smaller percentage remained in the peduncles and a larger percentage was secreted. The secretory process competed strongly with floral tissues for sugar even when the latter were undersupplied.

scholarly journals Protein metabolism in the mouse during pregnancy and lactation

1987 ◽  
Vol 248 (1) ◽  
pp. 251-257 ◽  
Author(s):  
P E Millican ◽  
R G Vernon ◽  
V M Pain
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Gastrocnemius Muscle ◽  
Mammary Glands ◽  
Whole Body ◽  
Absolute Rate ◽  
Pregnancy And Lactation ◽  
Day By Day ◽  
Stimulation Of

Protein synthesis was measured in vivo in the whole body and in a number of individual tissues in mice at various stages of pregnancy and lactation. The absolute rate of protein synthesis in the whole body increased from 640 mg/day in virgin mice to 1590 mg/day by day 18 of pregnancy, and to 2100 mg/day by day 15 of lactation. Large proportions of these increments were contributed by the rapidly growing foetuses and placentae in the pregnant animals and by protein synthesis in the mammary glands during lactation. In addition, a substantial stimulation of growth and protein synthesis was also observed in the liver and the gastrointestinal tract. Gastrocnemius muscle showed no changes in protein metabolism, indicating that in the well-fed mouse this tissue is not required to play a role as a protein reserve during pregnancy and lactation.

EFFECT OF ACTINOMYCIN D ON TSH-INDUCED STIMULATION OF THYROIDAL PROTEIN SYNTHESIS IN THE RAT

1974 ◽  
Vol 77 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Gustav Wägar
Keyword(s):  
Protein Synthesis ◽  
Actinomycin D ◽  
The Other ◽  
Leucine Incorporation ◽  
Short Term ◽  
Other Hand ◽  
Thyroid Glands ◽  
Translational Level ◽  
Stimulation Of

ABSTRACT Whether the short-term regulation of thyroidal protein synthesis by TSH occurs at the transcriptional or the translational level was tested by measuring the effect of actinomycin D (act D) on the TSH-induced stimulation of L-14C-leucine incorporation into the thyroidal proteins of rats. TSH was injected 6 h before the rats were killed. The thyroid glands were then removed and incubated in vitro in the presence of L-14C-leucine for 2 h. The pronounced stimulation of leucine incorporation in the TSH-treated animals was depressed as compared with controls but still significant even when the animals had been pre-treated with 100 μg act D 24 and 7 h before sacrifice. On the other hand, act D strongly decreased incorporation of 3H-uridine into RNA. Short-term regulation of thyroidal protein synthesis by TSH appears to be partly but not wholly dependent on neosynthesis of RNA. Hence regulation may partly occur at the translation level of protein synthesis.

The history of anabolic steroids and a review of clinical experience with anabolic steroids

1985 ◽  
Vol 110 (3_Suppla) ◽  
pp. S11-S18 ◽  
Author(s):  
H. Kopera
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Anabolic Steroids ◽  
Muscular Activity ◽  
Living Cells ◽  
Cellular Protein ◽  
Complex Compounds ◽  
The Body ◽  
Anabolic Effect ◽  
Vital Functions

Metabolism is the term employed to embrace the various physical and chemical processes occurring within the tissues upon which the growth and heat production of the body depend and from which the energy for muscular activity, for the maintenance of vital activity and for the maintenance of vital functions is derived (Best & Taylor 1950). The destructive processes by which complex substances are converted by living cells into more simple compounds are called catabolism. Anabolism denotes the constructive processes by which simple substances are converted by living cells into more complex compounds, especially into living matter. Catabolism and anabolism are part of all metabolic processes, the carbohydrate, fat and protein metabolism. The term anabolic refers only to substances that exert an anabolic effect on protein metabolism and are unlikely to cause adverse androgenic effects. They shift the equilibrium between protein synthesis and degradation in the body as a whole in the direction of synthesis, either by promoting protein synthesis or reducing its breakdown. The protein anabolic effect of anabolic steroids is not restricted to single organs but is the result of stimulated biosynthesis of cellular protein in the whole organism.

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