Accumulation of Proline and Sucrose during the First Hours after Transfer of Chlorella emevsonii to High NaCl

1979 ◽  
Vol 6 (1) ◽  
pp. 69 ◽  
Author(s):  
H Greenway ◽  
T.L Setter
Keyword(s):  
Steady State ◽  
Osmotic Potential ◽  
De Novo ◽  
Lag Phase ◽  
Sucrose Synthesis ◽  
De Novo Synthesis ◽  
Subsequent Period ◽  
Osmotic Solutes ◽  
Steady State Levels ◽  
Osmotic Solute

Net synthesis of proline, the main osmotic solute in C. emersonii, showed a lag of at least 15 min following transfer of cells from 1 m~ NaCl to concentrations ranging between 25 and 335 m~ NaCl. During the subsequent period of rapid net proline synthesis, the maximum rates were approximately linearly related to the decreases in external osmotic potential (YJ until the cells plasmolysed. Beyond the point of incipient plasmolysis, further large decreases in Y* did not change the maximum rates of proline synthesis. The steady-state levels of proline were lower, and were reached faster, the smaller the decreases in external Ys. Overall these results support the notion that turgor potential has a regulating role in the synthesis of osmotic solutes. Sucrose synthesis showed no lag and was rapid even in plasmolysed cells. Cycloheximide inhibited formation of proline but not of sucrose. This, together with the lag phase of 15 min in proline synthesis, indicated that transfer of C. emersonii to high NaCl induced de novo synthesis of enzymes involved in proline formation. Effects of DCMU and darkness were also measured. Cells transferred to 125 m~ NaCl still showed substantial net synthesis of sucrose, but not of proline. Supply of glucose in the dark did not lead to proline formation, but it did stimulate proline synthesis which occurred when glutamate was supplied.

Divergent effects of intravenous GSH and cysteine on renal and hepatic GSH

1992 ◽  
Vol 263 (2) ◽  
pp. R348-R352 ◽  
Author(s):  
S. Aebi ◽  
B. H. Lauterburg
Keyword(s):  
Steady State ◽  
De Novo ◽  
Feedback Inhibition ◽  
Therapeutic Use ◽  
Steady State Concentration ◽  
De Novo Synthesis ◽  
State Concentration ◽  
Cellular Thiol

There is a growing interest in the therapeutic use of sulfhydryls. To assess the effect of glutathione (GSH) and cysteine on the cellular thiol status, thiols were administered intravenously to rats in doses ranging from 1.67 to 8.35 mmol/kg with and without pretreatment with 4 mmol/kg buthionine-[S,R]-sulfoximine (BSO), an inhibitor of GSH synthesis. One hour after administration of 1.67 mmol/kg GSH, the concentration of GSH rose from 5.2 +/- 1.0 to 8.4 +/- 0.9 mumol/g and from 2.5 +/- 0.5 to 3.7 +/- 0.7 mumol/g in liver and kidneys, respectively. After 8.35 mmol/kg, hepatic GSH did not increase further, but renal GSH rose to 6.7 +/- 1.8 mumol/g. Infusion of cysteine increased hepatic GSH to the same extent as intravenous GSH, but renal GSH did not increase after 1.67 mmol/kg and even significantly decreased to 0.6 +/- 0.2 mumol/g after 8.35 mmol/kg. In the presence of BSO, GSH resulted in a significant increase in renal but not hepatic GSH, suggesting that the kidneys take up intact GSH and indicating that the increment in hepatic GSH was due to de novo synthesis. The present data show that hepatic GSH can be markedly increased in vivo by increasing the supply of cysteine. Measurements of hepatic cysteine indicate that up to a concentration of approximately 0.5 mumol/g cysteine is a key determinant of hepatic GSH, such that the physiological steady-state concentration of GSH in the liver appears to be mainly determined by the availability of cysteine. At higher concentrations GSH does not increase further, possibly due to feedback inhibition of GSH synthesis or increased efflux.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Changes in the expression of alpha-fodrin during embryonic development of Xenopus laevis.

1987 ◽  
Vol 105 (2) ◽  
pp. 843-853 ◽  
Author(s):  
D H Giebelhaus ◽  
B D Zelus ◽  
S K Henchman ◽  
R T Moon
Keyword(s):  
Steady State ◽  
Embryonic Development ◽  
Xenopus Laevis ◽  
De Novo ◽  
Single Gene ◽  
Predicted Amino Acid Sequence ◽  
Cdna Clones ◽  
De Novo Synthesis ◽  
S1 Nuclease ◽  
Stage Of Development

Fodrin (nonerythroid spectrin) and its associated proteins have been previously implicated in the establishment of specialized membrane-cytoskeletal domains in differentiating cells. Using antiserum which is monospecific for the alpha-subunit of fodrin, we demonstrate that alpha-fodrin is present in oocytes and adult tissues of Xenopus laevis. Analyses of the de novo synthesis of alpha-fodrin during embryonic development reveal that alpha-fodrin is synthesized in oocytes, but not during early development. To investigate the level of control of alpha-fodrin expression, we isolated two cDNA clones for oocyte alpha-fodrin. The oocyte cDNA clones were identified as encoding portions of alpha-fodrin based on DNA sequence analysis and on the comparison of the predicted amino acid sequence of the cDNAs with the known sequence of human erythrocyte alpha-spectrin. The Xenopus alpha-fodrin cDNAs hybridize to a transcript of approximately 9 kb on RNA blots, and probably to a single gene type on genomic DNA blots. Both RNA blot analyses and S1 nuclease protection assays with the Xenopus alpha-fodrin cDNAs demonstrate that the observed decline in the de novo synthesis of alpha-fodrin polypeptides is controlled by a dramatic decrease in the abundance of alpha-fodrin transcripts after fertilization. In contrast, levels of actin transcripts do not decrease during this period. Inasmuch as steady-state levels of alpha-fodrin transcripts rise by the neurula stage of development, these results suggest that the synthesis of alpha-fodrin polypeptides during embryonic development of Xenopus is regulated, rather than constitutive, and that the primary level of control is the steady-state abundance of mRNA.

scholarly journals Arabidopsis REI-LIKE proteins activate ribosome biogenesis during cold acclimation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bo Eng Cheong ◽  
Olga Beine-Golovchuk ◽  
Michal Gorka ◽  
William Wing Ho Ho ◽  
Federico Martinez-Seidel ◽  
...  
Keyword(s):  
Steady State ◽  
Feedback Control ◽  
Cold Acclimation ◽  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Transcriptional Control ◽  
De Novo ◽  
De Novo Synthesis ◽  
Steady State Temperature

AbstractArabidopsis REIL proteins are cytosolic ribosomal 60S-biogenesis factors. After shift to 10 °C, reil mutants deplete and slowly replenish non-translating eukaryotic ribosome complexes of root tissue, while controlling the balance of non-translating 40S- and 60S-subunits. Reil mutations respond by hyper-accumulation of non-translating subunits at steady-state temperature; after cold-shift, a KCl-sensitive 80S sub-fraction remains depleted. We infer that Arabidopsis may buffer fluctuating translation by pre-existing non-translating ribosomes before de novo synthesis meets temperature-induced demands. Reil1 reil2 double mutants accumulate 43S-preinitiation and pre-60S-maturation complexes and alter paralog composition of ribosomal proteins in non-translating complexes. With few exceptions, e.g. RPL3B and RPL24C, these changes are not under transcriptional control. Our study suggests requirement of de novo synthesis of eukaryotic ribosomes for long-term cold acclimation, feedback control of NUC2 and eIF3C2 transcription and links new proteins, AT1G03250, AT5G60530, to plant ribosome biogenesis. We propose that Arabidopsis requires biosynthesis of specialized ribosomes for cold acclimation.

scholarly journals Effects of meal ingestion on intramyocellular ceramide concentrations and fractional de novo synthesis in humans

2018 ◽  
Vol 314 (2) ◽  
pp. E105-E114 ◽  
Author(s):  
Jin Ook Chung ◽  
Christina Koutsari ◽  
Agnieszka Urszula Blachnio-Zablieska ◽  
Kazanna C. Hames ◽  
Michael D. Jensen
Keyword(s):  
Insulin Resistance ◽  
Steady State ◽  
De Novo ◽  
De Novo Synthesis ◽  
Overweight Status ◽  
Fractional Contribution ◽  
Meal Ingestion ◽  
Muscle Biopsies

We investigated the effects of meal ingestion on intramyofibrillar (IMF) and subsarcolemmal (SS) ceramide metabolism in volunteers ranging from lean to obese. Thirty-eight women and men underwent a steady-state meal ingestion protocol that included a 6.5-h infusion of [U-13C]palmitate and muscle biopsies 1.5 and 6.5 h after starting the tracer infusion. We measured IMF and SS sphingolipid concentrations and the contribution of plasma palmitate to intramyocellular C16:0 ceramide by use of LC-MS-MS. In response to meal ingestion SS C24 ceramide concentrations, but not C14-C20 concentrations, increased significantly. IMF ceramide concentrations did not change. The increases in SS C24 ceramides were negatively related to parameters of insulin resistance. The fractional contribution of plasma palmitate to intramyocellular C16:0 ceramides in both IMF and SS fractions was inversely related to overweight status (β = –0.432, P = 0.0095 and β = –0.443, P = 0.0058, respectively). These data indicate that meal ingestion has differing effects on SS ceramide subspecies and suggest that the fractional de novo synthesis of intramyocellular ceramide from plasma palmitate in the postprandial condition is reduced in those who are overweight.

Induction of the xylitol dehydrogenase of Pullularia pullulans

1988 ◽  
Vol 34 (2) ◽  
pp. 107-111 ◽  
Author(s):  
Juliet K. Sugai ◽  
L. A. Veiga
Keyword(s):  
Enzyme Induction ◽  
De Novo ◽  
Specific Activity ◽  
Kinetic Studies ◽  
Xylitol Dehydrogenase ◽  
Lag Phase ◽  
Differential Rate ◽  
De Novo Synthesis ◽  
Induction Study ◽  
Glycerol Medium

Pullularia pullulans, a yeastlike fungus, metabolizes xylitol via an intracellular xylitol dehydrogenase. Formation of the enzyme was induced by D-xylose and inhibited by cycloheximide, suggesting de novo synthesis. The induction study was carried out with noninduced cells of P. pullulans harvested from a glycerol medium. The cells initiated synthesis of xylitol dehydrogenase without a detectable lag phase when 1.5% xylose was added. The differential rate of xylitol dehydrogenase synthesis was 1.4 units per mg of synthesized protein. Kinetic studies of enzyme induction in a growing culture showed that the highest level of specific activity was reached at 25 to 27 h of growth, with an increase of 200 times over the basal level in the glycerol medium.

Hypoxia suppresses elastin repair by rat lung fibroblasts

2005 ◽  
Vol 289 (6) ◽  
pp. L931-L936 ◽  
Author(s):  
John L. Berk ◽  
Christine A. Hatch ◽  
Shirley M. Morris ◽  
Phillip J. Stone ◽  
Ronald H. Goldstein
Keyword(s):  
Gene Expression ◽  
De Novo ◽  
Alveolar Epithelium ◽  
Lung Fibroblasts ◽  
Rat Lung ◽  
De Novo Synthesis ◽  
Low Oxygen ◽  
Alveolar Collapse ◽  
Steady State Levels ◽  
Elastin Gene

Macrophage and neutrophil proteinases damage lung elastin, disrupting alveolar epithelium and filling alveoli with inflammatory exudate. Alveolar collapse and regional hypoxia occur. Whether low oxygen tension alters fibroblast-mediated lung repair is unknown. To determine the effect of chronic hypoxia on repair of enzyme-induced elastin disruption, primary rat lung fibroblasts produced elastin matrix for 5 wk before treatment with porcine pancreatic elastase (PPE). After exposure to PPE or saline, cultures recovered for 2 wk in normoxia (21% O2) or hypoxia (3% O2). Hypoxia suppressed regeneration of hot alkali-resistant elastin, achieving only 49% of the repair achieved in normoxic cultures. Vascular smooth muscle cells and lung fibroblasts repair elastin by two pathways: de novo synthesis and salvage repair. Although both pathways were affected, hypoxia predominantly inhibited de novo synthesis, decreasing formation of new elastin matrix by 63% while inhibiting salvage repair by only 36%. Prolonged hypoxia alone downregulated steady-state levels of elastin mRNA by 45%, whereas PPE had no significant effect on elastin gene expression. Electron microscopy documented preservation of intracellular organelles and intact nuclei. Together, these data suggest that regional hypoxia limits lung elastin repair following protease injury at least in part by inhibiting elastin gene expression.

Characterization of Monocyte-Associated Factor V

1993 ◽  
Vol 70 (02) ◽  
pp. 273-280 ◽  
Author(s):  
Janos Kappelmayer ◽  
Satya P Kunapuli ◽  
Edward G Wyshock ◽  
Robert W Colman
Keyword(s):  
Monoclonal Antibody ◽  
Light Chain ◽  
Peripheral Blood ◽  
De Novo ◽  
Factor V ◽  
Blood Monocytes ◽  
De Novo Synthesis ◽  
Hep G2 ◽  
Hep G2 Cells ◽  
Peripheral Blood Monocytes

SummaryWe demonstrate that in addition to possessing binding sites for intact factor V (FV), unstimulated peripheral blood monocytes also express activated factor V (FVa) on their surfaces. FVa was identified on the monocyte surface by monoclonal antibody B38 recognizing FVa light chain and by human oligoclonal antibodies H1 (to FVa light chain) and H2 (to FVa heavy chain) using immunofluorescence microscopy and flow cytometry. On Western blots, partially cleaved FV could be identified as a 220 kDa band in lysates of monocytes. In addition to surface expression of FVa, monocytes also contain intracellular FV as detected only after permeabilization by Triton X-100 by monoclonal antibody B10 directed specifically to the Cl domain not present in FVa. We sought to determine whether the presence of FV in peripheral blood monocytes is a result of de novo synthesis.Using in situ hybridization, no FV mRNA could be detected in monocytes, while in parallel control studies, factor V mRNA was detectable in Hep G2 cells and CD18 mRNA in monocytes. In addition, using reverse transcriptase and the polymerase chain reaction, no FV mRNA was detected in mononuclear cells or in U937 cells, but mRNA for factor V was present in Hep G2 cells using the same techniques. These data suggest that FV is present in human monocytes, presumably acquired by binding of plasma FV, and that the presence of this critical coagulation factor is not due to de novo synthesis.

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