The effect of methyl sterculate on oleic acid synthesis in the hen

Lipids ◽  
1972 ◽  
Vol 7 (7) ◽  
pp. 437-441 ◽  
Author(s):  
Judith A. Pearson ◽  
A. C. Fogerty ◽  
A. R. Johnson ◽  
F. S. Shenstone
1976 ◽  
Vol 158 (3) ◽  
pp. 593-601 ◽  
Author(s):  
P G Roughan ◽  
C R Slack ◽  
R Holland

Spinach chloroplasts, isolated by techniques yielding preparations with high O2- evolving activity, showed rates of light-dependent acetate incorporation into lipids 3-4 fold higher than any previously reported. Incorporation rates as high as 500 nmol of acetate/h per mg of chlorophyll were measured in buffered sorbitol solutions containing only NaHCO3 and [1-14C]acetate, and as high as 800 nmol/h per mg of chlorophyll when 0.13 mM-Triton X-100 was also included in the reaction media. The fatty acids synthesized were predominantly oleic (70-80% of the total fatty acid radioactivity) and palmitic (20-25%) with only minor amounts (1-5%) of linoleic acid. Linolenic acid synthesis was not detected in the system in vitro. Free fatty acids accounted for 70-90% of the radioactivity incorporated and the remainder was shared fairly evenly between 1,2-diacylglycerols and polar lipids. Oleic acid constituted 80-90% of the free fatty acids synthesized, but the diacylglycerols and polar lipids contained slightly more palmitic acid than oleic acid. Triton X-100 stimulated the synthesis of diacylglycerols 3-6 fold, but stimulated free fatty acid synthesis only 1-1.5-fold. Added glycerol 1-phosphate stimulated both the synthesis of diacylglycerols and palmitic acid relative to oleic acid, but did not increase acetate incorporation into total chloroplast lipids. CoA and ATP, when added separately, stimulated acetate incorporation into chloroplast lipids to variable extents and had no effect on the types of lipid synthesized, but when added together resulted in 34% of the incorporated acetate appearing in long-chain acyl-CoA. Pyruvate was a much less effective precursor of chloroplast fatty acids than was acetate.


1998 ◽  
Vol 53 (11-12) ◽  
pp. 995-1003 ◽  

Abstract Herbicidal chloroacetamides cause a very sensitive inhibition of fatty acid incorporation into an insoluble cell wall fraction of Scenedesmus acutus. The molecular basis was investigated in more detail. After incubation of the algae with [14C]oleic acid and saponification, the remaining pellet was solubilized and fractionated consecutively with chloroform / methanol, phosphate buffer, amylase, pronase, and finally with dioxane/HCl. By acid hydrolysis in dioxane a part of the cell wall residue was solubilized showing inhibition of exogenously applied oleic acid and other labelled precursors such as stearic acid, palmitic acid, and acetate. After extraction of this dioxane-soluble subfraction with hexane, HPLC could separate labelled metabolites less polar than oleic acid. T heir formation was completely inhibited by chloroacetam ides, e.g. 1 μᴍ metazachlor. This effect was also observed with the herbicidally active 5-enantiomer of metolachlor while the inactive R-enantiomer had no influence. These strongly inhibited metabolites could be characterized by radio-HPLC /MS as very long chain fatty acids (VLCFAs) with a carbon chain between 20 and 26. Incubating am etazachlor-resistant cell line of S. acutus (Mz-1) with [14C]oleic acid, V LCFA s could not be detected in the dioxane/ HCl-subfraction. Furthermore, comparing the presence of endogenous fatty acids in wildtype and mutant Mz-1 the VLCFA content of the mutant is very low, while the content of long chain fatty acids (C16 -18) is increased, particularly oleic acid. Obviously, the phytotoxicity of chloroacetam ides in S. acutus is due to inhibition of VLCFA synthesis. The resistance of the mutant to metazachlor has a bearing on the higher amount of long chain fatty acids replacing the missing VLCFAs in essential membranes or cell wall components.


2006 ◽  
Vol 63 (2) ◽  
pp. 257-271 ◽  
Author(s):  
Aardra Kachroo ◽  
John Shanklin ◽  
Edward Whittle ◽  
Ludmila Lapchyk ◽  
David Hildebrand ◽  
...  

2007 ◽  
Vol 84 (7) ◽  
pp. 675-680 ◽  
Author(s):  
Bryan R. Moser ◽  
Brajendra K. Sharma ◽  
Kenneth M. Doll ◽  
Sevim Z. Erhan

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Lei Zhu ◽  
Qi Zou ◽  
Xinyun Cao ◽  
John E. Cronan

ABSTRACTAcyl carrier proteins (ACPs) play essential roles in the synthesis of fatty acids and transfer of long fatty acyl chains into complex lipids. TheEnterococcus faecalisgenome contains two annotatedacpgenes, calledacpAandacpB. AcpA is encoded within the fatty acid synthesis (fab) operon and appears essential. In contrast, AcpB is an atypical ACP, having only 30% residue identity with AcpA, and is not essential. Deletion ofacpBhas no effect onE. faecalisgrowth orde novofatty acid synthesis in media lacking fatty acids. However, unlike the wild-type strain, where growth with oleic acid resulted in almost complete blockage ofde novofatty acid synthesis, theΔacpBstrain largely continuedde novofatty acid synthesis under these conditions. Blockage in the wild-type strain is due to repression offaboperon transcription, leading to levels of fatty acid synthetic proteins (including AcpA) that are insufficient to supportde novosynthesis. Transcription of thefaboperon is regulated by FabT, a repressor protein that binds DNA only when it is bound to an acyl-ACP ligand. Since AcpA is encoded in thefaboperon, its synthesis is blocked when the operon is repressed andacpAthus cannot provide a stable supply of ACP for synthesis of the acyl-ACP ligand required for DNA binding by FabT. In contrast to AcpA,acpBtranscription is unaffected by growth with exogenous fatty acids and thus provides a stable supply of ACP for conversion to the acyl-ACP ligand required for repression by FabT. Indeed,ΔacpBandΔfabTstrains have essentially the samede novofatty acid synthesis phenotype in oleic acid-grown cultures, which argues that neither strain can form the FabT-acyl-ACP repression complex. Finally, acylated derivatives of both AcpB and AcpA were substrates for theE. faecalisenoyl-ACP reductases and forE. faecalisPlsX (acyl-ACP; phosphate acyltransferase).IMPORTANCEAcpB homologs are encoded by many, but not all, lactic acid bacteria (Lactobacillales), including many members of the human microbiome. The mechanisms regulating fatty acid synthesis by exogenous fatty acids play a key role in resistance of these bacteria to those antimicrobials targeted at fatty acid synthesis enzymes. Defective regulation can increase resistance to such inhibitors and also reduce pathogenesis.


Helia ◽  
2004 ◽  
Vol 27 (40) ◽  
pp. 63-72 ◽  
Author(s):  
S. Tahmasebi-Enferadi ◽  
Z. Rabiei ◽  
M. Turi ◽  
M. Baldini ◽  
G.P. Vannozzi

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