The occurrence of a soluble glucose 6-phosphatase in cotyledon tissue of Phaseolus vulgaris during germination

1969 ◽  
Vol 47 (7) ◽  
pp. 685-689 ◽  
Author(s):  
J. E. Thompson
Keyword(s):  
Endoplasmic Reticulum ◽  
Phaseolus Vulgaris ◽  
De Novo ◽  
Specific Activity ◽  
Soluble Fraction ◽  
Soluble Form ◽  
Soluble Enzyme ◽  
De Novo Synthesis ◽  
Soluble Enzymes ◽  
Ph Profiles

Cotyledon tissue from seedlings of Phaseolus vulgaris at various stages of germination was homogenized and fractionated under isotonic conditions. Measurement of glucose 6-phosphatase (D-glucose 6-phosphate phosphohydrolase, EC 3.1.3.9) activity in the isolated fractions showed an increase in the level of soluble enzyme with advancing age of the cotyledons, such that by late senescence (10 days of age) approximately 90% of the recovered glucose 6-phosphatase was present in the soluble fraction, and its specific activity was about twofold greater than that of the homogenate. The pH profiles of the bound and soluble enzymes were found to be closely similar. The presence of a soluble glucose 6-phosphatase has been interpreted as indicating either de novo synthesis of the soluble form of the enzyme with advancing senescence, or solubilization of normally bound enzyme which may in turn reflect a partial breakdown in the structure of endoplasmic reticulum in senescent cells.

Rates of de novo Synthesis of Malate Synthase and Albumins during the Very Early Phase of Germination

1979 ◽  
Vol 34 (12) ◽  
pp. 1237-1242 ◽  
Author(s):  
Wolfram Köller ◽  
Helmut Kindl
Keyword(s):  
Early Phase ◽  
De Novo ◽  
Specific Activity ◽  
Specific Radioactivity ◽  
Malate Synthase ◽  
Polyacrylamide Gel ◽  
De Novo Synthesis ◽  
Albumin Fraction ◽  
Average Value ◽  
Large Pool

Abstract Malate synthase is synthesized de novo in the very early phase of germination. Its molecular and immunological properties do not differ from those of malate synthase from fully developed cotyledons. Radioactive leucine was administered to dry seeds of cucumber, and its incorporation into proteins of cotyledons was examined after 2 days of germination. The specific radioactivity of malate synthase, purified by immunoprecipitation and electrophoresis on polyacrylamide gel, was only 1/20 the average value of the total albumin fraction. The minimal incorporation documented by the comparatively low specific activity of isolated malate synthase is discussed in relation to the large pool of malate synthase already present in dry seeds.

scholarly journals Sphingolipid Profiling Reveals Different Extent of Ceramide Accumulation in Bovine Retroperitoneal and Subcutaneous Adipose Tissues

Metabolites ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 473
Author(s):  
Yue Hei Leung ◽  
Sonja Christiane Bäßler ◽  
Christian Koch ◽  
Theresa Scheu ◽  
Ulrich Meyer ◽  
...  
Keyword(s):  
Insulin Sensitivity ◽  
De Novo ◽  
Specific Activity ◽  
Multiple Reaction Monitoring ◽  
De Novo Synthesis ◽  
Bioactive Lipids ◽  
Tissue Specific ◽  
Sphingosine 1 Phosphate ◽  
Ceramide Accumulation ◽  
Subcutaneous Adipose

Sphingolipids are bioactive lipids that can modulate insulin sensitivity, cellular differentiation, and apoptosis in a tissue-specific manner. However, their comparative profiles in bovine retroperitoneal (RPAT) and subcutaneous adipose tissue (SCAT) are currently unknown. We aimed to characterize the sphingolipid profiles using a targeted lipidomics approach and to assess whether potentially related sphingolipid pathways are different between SCAT and RPAT. Holstein bulls (n = 6) were slaughtered, and SCAT and RPAT samples were collected for sphingolipid profiling. A total of 70 sphingolipid species were detected and quantified by UPLC-MS/MS in multiple reaction monitoring (MRM) mode, including ceramide (Cer), dihydroceramide (DHCer), sphingomyelin (SM), dihydrosphingomyelin (DHSM), ceramide-1-phosphate (C1P), sphingosine-1-phosphate (S1P), galactosylceramide (GalCer), glucosylceramide (GluCer), lactosylceramide (LacCer), sphinganine (DHSph), and sphingosine (Sph). Our results showed that sphingolipids of the de novo synthesis pathway, such as DHSph, DHCer, and Cer, were more concentrated in RPAT than in SCAT. Sphingolipids of the salvage pathway and the sphingomyelinase pathway, such as Sph, S1P, C1P, glycosphingolipid, and SM, were more concentrated in SCAT. Our results indicate that RPAT had a greater extent of ceramide accumulation, thereby increasing the concentration of further sphingolipid intermediates in the de novo synthesis pathway. This distinctive sphingolipid distribution pattern in RPAT and SCAT can potentially explain the tissue-specific activity in insulin sensitivity, proinflammation, and oxidative stress in RPAT and SCAT.

scholarly journals Properties and developmental regulation of an α-d-galactosidase from Dictyostelium discoideum

1976 ◽  
Vol 158 (2) ◽  
pp. 409-417 ◽  
Author(s):  
D C Kilpatrick ◽  
J L Stirling
Keyword(s):  
Protein Synthesis ◽  
Dictyostelium Discoideum ◽  
Early Development ◽  
Subcellular Distribution ◽  
De Novo ◽  
Specific Activity ◽  
Soluble Fraction ◽  
Developmental Regulation ◽  
Cellular Slime Mould ◽  
Cellular Slime

An alpha-D-galactosidase was detected in cells of the cellular slime mould, Dictyostelium discoideum, at all stages of development. Its specific activity was highest during early development (interphase), and this accumulation of enzyme appears to require protein synthesis de novo. Its subcellular distribution differs from that of other D. discoideum glycosidases, since most activity was recovered in the soluble fraction. No evidence was obtained for more than one isoenzymic form after subjection of extracts to electrophoresis and various chromatographic procedures. It is excreted from the cell during development, but no evidence was found for an extracellular function for the enzyme.

Leptin biosynthetic pathway in white adipocytes

2006 ◽  
Vol 84 (2) ◽  
pp. 207-214 ◽  
Author(s):  
Philippe G Cammisotto ◽  
Ludwik J Bukowiecki ◽  
Yves Deshaies ◽  
Moise Bendayan
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Secretory Pathway ◽  
De Novo ◽  
Brefeldin A ◽  
Mrna Levels ◽  
De Novo Synthesis ◽  
Cellular Content ◽  
Constitutive Secretion

The aim of this study was to determine through morphological and biochemical means the biosynthetic and secretory pathway followed by leptin in adipocytes. Immunocytochemistry revealed the presence of leptin in the rough endoplasmic reticulum, the Golgi apparatus, and in numerous small vesicles along the plasma membrane of white adipo cytes. In vitro, isolated adipocytes under nonstimulated conditions (basal) continuously secreted leptin while their intra cellular content remained unchanged. When adipocytes were stimulated with insulin, leptin cellular content and secretion increased in parallel and were significantly different from basal secretion only after 45 min. L-leucine and L-glutamate also strongly stimulated leptin synthesis and secretion. These stimulating effects were abolished by cycloheximide and brefeldin A. The transcriptional inhibitor actinomycin D did not have any effects in either basal or stimulated conditions. Leptin mRNA levels were not affected by any stimulating or inhibiting agents. Finally, norepinephrine, isoproterenol, CL316243, and palmitate inhibited the effects of insulin, L-leucine, and L-glutamate on leptin synthesis. We thus conclude that (i) adipocytes continuously synthesize and secrete leptin along a rough endoplasmic reticulum–Golgi secretory vesicles pathway, (ii) an increase in leptin secretion requires increased de novo synthesis, and (iii) short-term leptin secretion does not involve changes in mRNA levels.Key words: leptin, vesicles, constitutive secretion, de novo synthesis, transcription.

Enhanced RNA and protein synthesis in adipose tissue of rats adapted to periodic hyperphagia

1968 ◽  
Vol 46 (6) ◽  
pp. 903-906 ◽  
Author(s):  
L. Kazdová ◽  
T. Braun ◽  
P. Fábry ◽  
R. Poledne
Keyword(s):  
Protein Synthesis ◽  
Adipose Tissue ◽  
Rna Synthesis ◽  
De Novo ◽  
Specific Activity ◽  
De Novo Synthesis ◽  
Experimental Conditions ◽  
Rna And Protein Synthesis ◽  
Meal Feeding ◽  
The Difference

RNA synthesis measured by the incorporation of orotic acid-6-14C into RNA was investigated in isolated adipose tissue of control rats and of rats adapted to periodic hyperphagia, evoked by meal-feeding (a single 2-h meal per day). Both groups were fasted for 22 h and subsequently fed a measured test meal for another 2 h. It was revealed that 2 and 4 h after feeding there was no significant change in comparison with values during fasting, whereas in tissue of meal-fed rats the specific activity of RNA gradually increased by 22% and 41% respectively. The difference between controls and meal-fed rats was even much more marked if the specific activity of RNA in fat cells, isolated after incubation of the tissue, was measured. A significantly greater response of meal-fed rats was found when protein synthesis and lipogenesis in adipose tissue were assessed under the same experimental conditions. The possibility is discussed that the enhanced RNA and protein synthesis in adipose tissue of meal-fed rats is associated with de novo synthesis of enzymes involved in adaptive hyperlipogenesis.

scholarly journals Glucosamine metabolism in regenerating rat liver

1976 ◽  
Vol 158 (3) ◽  
pp. 589-592 ◽  
Author(s):  
N Akamatsu ◽  
H Nakajima ◽  
S Miyata
Keyword(s):  
Partial Hepatectomy ◽  
Rat Liver ◽  
De Novo ◽  
Specific Activity ◽  
Soluble Fraction ◽  
Amino Sugar ◽  
Insoluble Fraction ◽  
Regenerating Liver ◽  
Glycoprotein Synthesis

1. Glycoprotein synthesis was investigated with [1-14C]glucosamine in vivo. [14C]Glucosamine was administered intravenously 24h after hepatectomy to rats. 2. Incorporation into the acid-soluble fraction was maximum at 15 min after injection both in sham-operated and hepatectomized rats. 3. Enhancement of incorporation into UDP-N-acetylhexosamine in regenerating liver was observed. However, its specific activity was lower, because of a greater enhancement of synthesis de novo of the amino sugar. 4. In the liver acid-insoluble fraction, maximum incorporation of [14C]glucosamine was at 30 min in sham-operated rats and 2 h in hepatectomized rats respectively. 5. In sham-operated rats, incorporation into the plasma acid-insoluble fraction followed that of the liver acid-insoluble fraction, but hepatectomy resulted in a rapid enchancement of incorporation into plasma. 6. It is concluded that synthesis of liver glycoproteins is stimulated after partial hepatectomy and that glycoproteins synthesized are released rapidly into the plasma.

scholarly journals DRES-09. REGULATORY EFFECTS OF THE CILIARY GTPASE ARL13B ON PURINE METABOLISM IN GBM

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi73-vi73
Author(s):  
Miranda Saathoff ◽  
Jack Shireman ◽  
Eunus Ali ◽  
Cheol Park ◽  
Issam Ben-Sahra ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
De Novo ◽  
Specific Activity ◽  
Purine Metabolism ◽  
P Value ◽  
Salvage Pathway ◽  
De Novo Synthesis ◽  
Dna Double Strand Breaks ◽  
Purine Nucleotides ◽  
Regulatory Effects

Abstract Glioblastoma (GBM) is the most common form of adult primary brain cancer. Despite an aggressive treatment regimen – surgical resection, irradiation, and temozolomide (TMZ) chemotherapy – patients’ prognosis is still grim. TMZ acts by methylating purines, specifically at the O6 and N7 positions of guanine, to induce cytotoxic DNA double-strand breaks. We thus wanted to explore how purine metabolism may contribute to TMZ-resistance. In mammalian cells, purine nucleotides can be recycled by the salvage pathway or generated via de novo synthesis. The salvage pathway is energetically inexpensive relative to de novo thus, highly proliferative GBM cells preferentially utilize the salvage pathway. We have shown that salvage synthesis is reduced in response to TMZ (p-value=0.0021), hinting that the cells may utilize de novo to evade therapy induced alkylation of purines. Using immunoprecipitation-mass spectroscopy analysis, we found a novel interaction between the ciliary GTPase ARL13B and IMPDH2, the rate-limiting enzyme in de novo synthesis. We have shown that this interaction, occurring at the C-terminal domain of ARL13B, plays a significant role in the regulation of purine biosynthesis as abolishing it through ARL13B knockdown reduced flux through de novo (p-value< 0.0001) synthesis as measured by the specific activity of IMPDH2. Further, the lentiviral-mediated rescue of ARL13B brings IMPDH2 activity back to basal levels (p< 0.0001). Given its canonical function as a GTPase, we hypothesize that ARL13B acts as a novel regulator of de novo synthesis by sequestering GDP, allowing IMPDH2 to sense and respond to the cytosolic levels of guanine nucleotides. Without ARL13B the de novo pathway is halted, forcing the cells to rely on salvage to replenish nucleotide pools. Reliance on this pathway in the presence of TMZ causes cells to incorporate damaged nucleotides as a result of the drug’s alkylating action leading to the increased therapeutic efficacy of TMZ.

Structural and Metabolic Interrelationships Among Glycerophosphatides of Rat Liver In Vivo

1971 ◽  
Vol 49 (12) ◽  
pp. 1347-1356 ◽  
Author(s):  
B. J. Holub ◽  
A. Kuksis
Keyword(s):  
Rat Liver ◽  
De Novo ◽  
Specific Activity ◽  
Acyl Transfer ◽  
De Novo Synthesis ◽  
Individual Molecular Species ◽  
Relative Specific Activity ◽  
Proportional Contribution ◽  
Specific Activities

The specific activities of individual molecular species of rat liver diacylglycerylphosphorocholine (PC), diacylglycerylphosphoroethanolamine (PE), and diacylglycerophosphorylinositol (MPI) were determined and compared following intravenous injection of glycerol-14C. PC, PE, and MPI contained 41, 51, and 83%, respectively, tetraenoic species, and 40,17, and 9% combined mono-, di-, and trienoic species. The rest of the phosphatide mass of PC, PE, and MPI was contributed by 18, 32, and 8% penta- and hexaenoic species, respectively. The proportions of chemical classes of the glycerophosphatides differed by 1.1- to 18-fold while the fatty acid associations within the unsaturation classes common to these phosphatides varied 2.2- to 17-fold. After 5 min exposure to radioactive glycerol, the mono-, di-, and trienoic species of the PC, PE, and MPI possessed 13–18, 15–50, and 6–42 times, respectively, the specific activity of the tetraenes of the corresponding phosphatide classes. While the pentaenoic and hexaenoic species of PC and MPI had specific activities three to five times those of the respective tetraenes, the higher polyenes of PE were considerably more radioactive and approached the specific activity of the dienoic species of this phosphatide. With progressing time up to 60 min, the tetraenoic species of PC, PE, and MPI showed increases in relative specific activity of 50, 64, and 109%, respectively, in the three phosphatides. These results are consistent with an effective de novo synthesis of the oligoenoic species and a transacylation of the tetraenoic species of all liver glycerophosphatides tested. The proportional contribution of de novo synthesis in comparison to acyl transfer is apparently greater to the formation of PC and PE than to that of MPI.

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