scholarly journals Comparison of albumin-mediated release of lysophosphatidylcholine and lysophosphatidylethanolamine from cultured rat hepatocytes

1989 ◽  
Vol 264 (1) ◽  
pp. 125-131 ◽  
Author(s):  
B S Robinson ◽  
D J Baisted ◽  
D E Vance
Keyword(s):  
Fatty Acids ◽  
Culture Medium ◽  
Unsaturated Fatty Acids ◽  
Rat Hepatocytes ◽  
Fatty Acyl ◽  
Detectable Change ◽  
Cultured Rat Hepatocytes

We have investigated the albumin-stimulated release from cultured rat hepatocytes of lysophosphatidylcholine derived from methylation of phosphatidylethanolamine and of lysophosphatidylethanolamine. In the absence [corrected] of albumin, neither lysophosphatidylethanolamine nor lysophosphatidylcholine was released into the culture medium. Albumin stimulated the accumulation of both phospholipids in the medium. After 2 h, 14.1 nmol of lysophosphatidylcholine and 2.0 nmol of lysophosphatidylethanolamine per 3 x 10(6) cells had accumulated in the medium. The rate of release of [3H]ethanolamine-labelled lysophosphatidylethanolamine was rapid in the first 2 h and then was decreased, whereas there was a 1 h lag in the release of [3H]ethanolamine-labelled lysophosphatidylcholine. This apparent lag probably reflected the time necessary for the synthesis of phosphatidylcholine from phosphatidylethanolamine in the cells. Albumin caused a decrease in labelled cellular lysophosphatidylethanolamine and lysophosphatidylcholine which only partially accounted for the accumulation of the labelled phospholipids in the medium. Albumin also stimulated the release of labelled phosphatidylethanolamine (almost 3-fold) and phosphatidylcholine (2-fold) into the medium. There was no detectable change in the labelling of the cellular pools of these phospholipids, most likely owing to the large amounts in the cells compared with the medium. The labelled lysophospholipids did not arise from catabolism of the parent phospholipid in the medium. Analysis of the fatty acids of the secreted lysophospholipids showed a preferential release of unsaturated fatty acyl species of lysophosphatidylcholine, whereas lysophosphatidylethanolamine contained similar amounts of saturated and unsaturated fatty acids.

scholarly journals Albumin stimulates the release of lysophosphatidylcholine from cultured rat hepatocytes

1988 ◽  
Vol 253 (3) ◽  
pp. 693-701 ◽  
Author(s):  
D J Baisted ◽  
B S Robinson ◽  
D E Vance
Keyword(s):  
Fatty Acids ◽  
Fatty Acid Composition ◽  
Unsaturated Fatty Acids ◽  
Rat Hepatocytes ◽  
Water Soluble ◽  
Measurable Effect ◽  
Rat Hepatocyte ◽  
Low Concentrations ◽  
Cultured Rat Hepatocytes ◽  
Secreted Enzymes

The effect of albumin on the release of [3H]lysophosphatidylcholine from cultured rat hepatocytes prelabelled with [Me-3H]choline was studied. In the absence of serum and albumin from the medium, the cells released essentially no [3H]lysophosphatidylcholine. Albumin stimulated this process dramatically, and it reached a plateau at 2 mg/ml. After an initial lag of 30 min, the release of [3H]lysophosphatidylcholine was linear for at least 4 h. At low concentrations, albumin slightly stimulated [3H]phosphatidylcholine release. The albumin had no measurable effect on the metabolism of cellular [3H]phosphatidylcholine, [3H]lysophosphatidylcholine or [3H]glycerophosphocholine. In addition, albumin did not alter the release of 3H-labelled water-soluble compounds, including [3H]glycerophosphocholine, into the medium. The possibility that the [3H]lysophosphatidylcholine was arising from catabolism of [3H]phosphatidylcholine in the medium by secreted enzymes was excluded. The effect on [3H]lysophosphatidylcholine secretion was also observed when the cells were incubated with alpha-cyclodextrin, a cyclic polysaccharide that has the ability to bind lysophosphatidylcholine. The albumin-released lysophosphatidylcholine was enriched in unsaturated fatty acids. Alteration of the fatty acid composition of cellular phosphatidylcholine gave rise to parallel changes in phosphatidylcholine and lysophosphatidylcholine in the medium. It is concluded that phosphatidylcholine is constantly being degraded in the rat hepatocyte to lysophosphatidylcholine which is released into the medium only when a suitable acceptor is present.

scholarly journals Unsaturated fatty acids activate glycogen phosphorylase in cultured rat hepatocytes

1991 ◽  
Vol 276 (1) ◽  
pp. 209-215 ◽  
Author(s):  
A Gomez-Muñoz ◽  
P Hales ◽  
D N Brindley
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Glycogen Phosphorylase ◽  
Unsaturated Fatty Acids ◽  
High Fatty Acid ◽  
Rat Hepatocytes ◽  
Phosphorylase Activity ◽  
Cultured Rat Hepatocytes ◽  
Glycogen Phosphorylase Activity

Oleate, linoleate, linolenate, arachidonate and eicosapentaenoate, but not myristate, palmitate and stearate, stimulated glycogen phosphorylase activity by 2-8-fold when added to cultured rat hepatocytes. Addition of BSA or Ca2- to the incubation medium decreased the stimulating effects of the unsaturated fatty acids. The combination of oleate or linolenate, with corticosterone, testosterone or estradiol produced synergistic stimulations of phosphorylase activity. The stimulation of glycogen phosphorylase activity by linolenate was inhibited by staurosporine or sphingosine. Staurosporine (80 nM) alone also decreased basal phosphorylase activities by about 60%. The results show that unsaturated fatty acids can be used as model agonists to stimulate phosphorylase activity by a mechanism that probably involves protein kinase C. On the basis of the fatty acid: BSA ratios used, this stimulation should only occur in vivo at high fatty acid concentrations when accompanied by hypoalbuminaemia.

Influence of cytosolic pH on receptor-mediated endocytosis of asialoorosomucoid

1988 ◽  
Vol 254 (6) ◽  
pp. C829-C838 ◽  
Author(s):  
A. C. Samuelson ◽  
R. J. Stockert ◽  
A. B. Novikoff ◽  
P. M. Novikoff ◽  
J. C. Saez ◽  
...  
Keyword(s):  
Cell Surface ◽  
Intracellular Ph ◽  
Culture Medium ◽  
Rat Hepatocytes ◽  
Receptor Internalization ◽  
Receptor Complex ◽  
Cytosolic Ph ◽  
Receptor Mediated Endocytosis ◽  
Co2 Diffusion ◽  
Cultured Rat Hepatocytes

Inhibitors of specific steps in the endocytosis of galactose-terminating glycoproteins (asialoglycoproteins) by cultured rat hepatocytes have been described (J. Cell Biol. 98: 375-381, 1984). In particular, substitution of K+ for Na+ in the culture medium results in reduced delivery of ligand to lysosomes; ligand-receptor internalization, dissociation, and segregation remain normal. We have now demonstrated by direct microelectrode measurement that incubation of hepatocytes in K+-substituted medium results in a reduction of intracellular pH by greater than or equal to 0.5 U. In addition, we have shown that reduced intracellular pH in these cells produced by either direct (CO2 diffusion) or indirect (K+ substitution) acidification inhibits ligand delivery to lysosomes. Return of internalized ligand-receptor complex to the cell surface (diacytosis) is also inhibited by these manipulations. These studies suggest that intracellular pH may modulate specific steps involving vesicle translocation and fusion in the receptor-mediated endocytosis of asialoglycoproteins. Similar effects of direct acidification of hepatocytes by CO2 diffusion and indirect acidification by K+ substitution for Na+, on diacytosis and ligand delivery to lysosomes, suggest that K+ substitution may influence these events by altering intracellular pH.

scholarly journals Unsaturated fatty acids suppress interleukin-2 production and transferrin receptor expression by concanavalin A-stimulated rat Iymphocytes

1992 ◽  
Vol 1 (2) ◽  
pp. 107-112 ◽  
Author(s):  
Philip C. Calder ◽  
Eric A. Newsholme
Keyword(s):  
Fatty Acids ◽  
Transferrin Receptor ◽  
Lymphocyte Proliferation ◽  
Culture Medium ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
Interleukin 2 ◽  
Receptor Expression ◽  
T Lymphocyte Proliferation ◽  
Transferrin Receptor Expression

The proliferation of T-lymphocytes is dependent upon their ability to synthesize and secrete the cytokine, interleukin-2, and to express cell surface receptors for interleukin-2 and transferrin. We have previously reported that certain fatty acids inhibit mitogen-stimulated T-lymphocyte proliferation. We now report that unsaturated fatty acids decrease the concentration of interleukin-2 in the culture medium of such cells by up to 45%. This suggests that unsaturated fatty acids inhibit lymphocyte proliferation by suppressing interleukin-2 production. However, lymphocyte proliferation was only partially restored by addition of exogenous interleukin-2 to cell culture medium in the presence of unsaturated fatty acids, indicating that these fatty acids also affect other processes involved in the control of proliferation. Saturated fatty acids, which also inhibit lymphocyte proliferation, did not affect the interleukin-2 concentration in the culture medium suggesting a different mechanism for their action. Neither saturated nor unsaturated fatty acids affected the expression of the interleukin-2 receptor by mitogenstimulated lymphocytes. In contrast, unsaturated fatty acids decreased expression of the transferrin receptor by up to 50%. These observations suggest that the mechanism by which unsaturated fatty acids inhibit lymphocyte proliferation involves suppression of interleukin-2 production and of transferrin receptor expression. The mechanism for the inhibitory action of saturated fatty acids is not clear.

scholarly journals Productivity and quality of Moina sp. cultivated with various culture medium

2021 ◽  
Vol 20 (2) ◽  
pp. 148-162
Author(s):  
Taufik Shidik Adi Nugroho Shidik ◽  
Julie Ekasari ◽  
Dedi Jusadi ◽  
Mia Setiawati
Keyword(s):  
Fatty Acids ◽  
Organic Material ◽  
Culture Medium ◽  
Unsaturated Fatty Acids ◽  
Protein Quality ◽  
Culture Media ◽  
Mass Scale ◽  
Chlorella Sp ◽  
Study Results

Cultivation of Moina sp is still constrained by its quality, productivity, and sustainability. The alternative solution is the use of cultivation media materials that have high nutritional content and easily available in large quantities to support the quality and productivity of Moina sp. and meet the needs of live feed. The objective of the study was to evaluate the effect of various culture medium on the productivity and nutritional quality of Moina sp.. Five culture media were tested in laboratory scale, i.e. organic ingredient (BO), Chlorella sp. (Ch), Chlorella sp. + organic ingredients (ChBO), biofloc (BF) and biofloc + organic ingredients (BFBO). While in mass scale, four culture media were tested, i.e. Chlorella sp. (Ch), Chlorella sp. + Organic Ingredients (ChBO), Biofloc (BF) and Biofloc + Organic Ingredients (BFBO). The peaks of Moina sp. density in different treatments were achieved in different days. ChBO treatments significantly had higher productivity (P<0.05). The highest protein content was found in Moina sp. cultured with ChBO media, even higher than artemia. Moina sp. cultured with Chlorella sp. (Ch) showed the highest PUFA (Poly Unsaturated Fatty Acids) contents, while the highest MUFA (mono unsaturated fatty acids) contents was obtained from Moina sp. cultured with BFBO media lower than artemia. The study results indicates that different culture media produces different productivity and nutrient quality of Moina sp. The organic material combination of Chlorella sp. + organic material (ChBO) was the best media to improve the productivity and protein quality of Moina sp.    Keywords : Biofloc, Chlorella sp., Moina sp., organic matter, productivity, quality   ABSTRAK   Budidaya Moina sp. masih terkendala pada kualitas, produktivitas dan kestabilan dalam ketersediaannya. Untuk itu diperlukan penggunaan bahan media budidaya yang memiliki kandungan nutrisi tinggi dan mudah didapat dalam jumlah banyak untuk mendukung kualitas dan produktivitas Moina sp. demi memenuhi kebutuhan pakan hidup. Tujuan penelitian yaitu mengevaluasi pengaruh berbagai media budidaya terhadap produktivitas dan kualitas nutrisi Moina sp. Lima media kultur yang diuji dalam penelitian laboratorium yaitu Bahan Organik (BO), Chlorella sp. (Ch), Chlorella sp. + Bahan Organik (ChBO), Bioflok (BF) dan Bioflok + Bahan Organik (BFBO). Sedangkan pada penelitian skala massal diuji empat media kultur yaitu Chlorella sp. (Ch), Chlorella sp. + Bahan Organik (ChBO), Bioflok (BF) dan Bioflok + Bahan Organik (BFBO). Puncak kepadatan Moina sp. pada tiap perlakuan dicapai pada hari yang berbeda. Perlakuan ChBO memiliki produktivitas yang lebih tinggi (P<0,05). Kandungan protein Moina sp. tertinggi ditemukan pada media ChBO dan bahkan lebih tinggi dari pada artemia. Moina sp. yang dibudidayakan dengan Chlorella sp. (Ch), menunjukkan kandungan PUFA tertinggi, sedangkan kandungan MUFA yang tertinggi terdapat pada Moina sp. yang dibudidayakan dengan bahan media BFBO namun masih lebih rendah jika dibandingkan dengan kandungan pada artemia. Hasil penelitian menunjukkan media kultur yang berbeda menghasilkan produktivitas dan kualitas nutrisi moina yang berbeda. Kombinasi bahan organik Chlorella + bahan organik (ChBO) merupakan media terbaik dibandingkan dengan perlakuan lainnya untuk meningkatkan produktivitas dan kualitas nutrisi terutama protein Moina sp.   Kata kunci : Bioflok, Chlorella sp., Moina sp., bahan organik, produktivitas, kualitas

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