Galactolipid DGDG and Betaine Lipid DGTS Direct De Novo Synthesized Linolenate into Triacylglycerol in a Stress-Induced Starchless Mutant of Chlamydomonas reinhardtii

2020 ◽  
Vol 61 (4) ◽  
pp. 851-862
Author(s):  
Miao Yang ◽  
Fantao Kong ◽  
Xi Xie ◽  
Peichun Wu ◽  
Yadong Chu ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Time Course ◽  
De Novo ◽  
Membrane Lipids ◽  
Membrane Lipid ◽  
Nitrogen Deprivation ◽  
Formation Pathway ◽  
Time Course Study ◽  
Increasing Demand ◽  
Starchless Mutant

Abstract The increasing demand for triacylglycerol (TAG) enriching polyunsaturated fatty acids (PUFAs) has led to a surge of interest in microalgal TAG metabolism. Polar membrane lipids serve as the desaturation carrier for PUFA, and the functional group of PUFA can be incorporated into TAG. Monogalactoglycerolipid has been found to provide the de novo synthesized oleate acyl group or the nascent polyunsaturated diacylglycerol backbone for TAG biosynthesis in the model green alga, Chlamydomonas reinhardtii. However, whether other membrane lipids take part in the formation of PUFA-attached TAG has not been clearly discovered. A time course study of glycerolipidomics in the starchless mutant of C. reinhardtii, BAFJ5, which hyper-accumulates TAG, revealed that digalactosyldiacylglycerol (DGDG) and diacylglycerol-N,N,N-trimethylhomoserine (DGTS) turned into the main components of membrane lipids, accounting for 62% of the total polar lipids, under nitrogen deprivation combined with high light conditions. In addition, the membrane lipid molecules DGDG 18:3n3/16:0 and DGTS 16:0/18:3n6 were presumed to be involved in the consecutive integration of the de novo synthesized linolenates into TAG. Based on the stoichiometry calculation, DGDG and DGTS were demonstrated to provide a major contribution to the accumulation of linolenate-attached TAG. Our study gives insights into the potential PUFA-attached TAG formation pathway mediated by the turnover of de novo synthesized DGDG and DGTS in the starchless mutant of Chlamydomonas.

scholarly journals Lipid synthesis in human erythroid cells: the effect of sickling

Blood ◽  
1976 ◽  
Vol 47 (2) ◽  
pp. 189-195 ◽  
Author(s):  
TA Lane ◽  
SK Ballas ◽  
ER Burka
Keyword(s):  
Cell Membrane ◽  
Neutral Lipid ◽  
Sickle Cell Anemia ◽  
De Novo ◽  
Membrane Lipids ◽  
Membrane Damage ◽  
Lipid Synthesis ◽  
Membrane Lipid ◽  
Erythroid Cell ◽  
Cell Membrane Damage

Abstract Human reticulocytes are capable of synthesizing membrane lipids from 14C-glycerol de novo. In both sickle and nonsickle reticulocytes the majority of 14C-glycerol was incorporated into phospholipids, primarily phosphatidylserine and phosphatidylcholine. Incorporation into sphingomyelin was minimal. The most abundant neutral lipid synthesized was triglyceride. In the absence of sickling, the rate of lipid synthesis in sickle reticulocytes was similar to that of nonsickle reticulocytes. With the induction of sickling under anoxic conditions sickle reticulocytes showed a prompt increase in the rate of lipid synthesis to an average of 69% above control values, while nonsickle reticulocytes under similar conditions decreased the rate of lipid synthesis. An increase in the rate of membrane lipid synthesis is associated in the mammalian erythroid cell with cell membrane damage. The findings further confirm that lesions of the erythroid cell membrane in sickle cell anemia are secondary to the sickling process itself.

Membrane lipid biogenesis and transport

1986 ◽  
Vol 44 ◽  
pp. 70-71
Author(s):  
E.A. Dawidowicz
Keyword(s):  
Lipid Bilayers ◽  
De Novo ◽  
Membrane Lipids ◽  
Essential Feature ◽  
Liver Microsomes ◽  
Eukaryotic Cell ◽  
Membrane Lipid ◽  
Membrane Components ◽  
Isolated Liver ◽  
Initial Assembly

Membrane biogenesis is an essential feature of cellular development and growth. The initial assembly of membrane lipids and proteins occurs primarily in the endoplasmic reticulum (ER). It has been demonstrated that the enzymes involved in the de novo biosynthesis of phospholipids are exclusively located on the cytoplasmic surface of the ER. A rapid transbilayer movement of phospholipids has also been reported in isolated liver microsomes, which is compatible with the movement of newly synthesized lipids to the lumenal surface of the ER. Comparison with the transbilayer movement of phospholipids across protein-free lipid bilayers, has lead to the proposal that a protein which would catalyze the translocation of phospholipids across the ER membrane (“flipase”), might be involved in the assembly of the lipid bilayer of the ER. Since the various membranes in a eukaryotic cell differ markedly in their lipid composition, it is clear that specific sorting and transport of these membrane components must occur.

scholarly journals Characterization of fatty acid desaturases reveals stress-induced synthesis of C18 unsaturated fatty acids enriched in triacylglycerol in the oleaginous alga Chromochloris zofingiensis

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Tao Wu ◽  
Lihua Yu ◽  
Yu Zhang ◽  
Jin Liu
Keyword(s):  
Mass Spectrometry ◽  
Fatty Acids ◽  
Unsaturated Fatty Acids ◽  
De Novo ◽  
Membrane Lipids ◽  
Membrane Lipid ◽  
Gas Chromatography Mass Spectrometry ◽  
Transcription Start Sites ◽  
Chromatography Mass Spectrometry ◽  
Chromochloris Zofingiensis

Abstract Background The green microalga Chromochloris zofingiensis is capable of producing high levels of triacylglycerol rich in C18 unsaturated fatty acids (UFAs). FA desaturation degree is regulated by FA desaturases (FADs). Nevertheless, it remains largely unknown regarding what FADs are involved in FA desaturations and how these FADs collaborate to contribute to the high abundance of C18 UFAs in triacylglycerol in C. zofingiensis. Results To address these issues, we firstly determined the transcription start sites of 11 putative membrane-bound FAD-coding genes (CzFADs) and updated their gene models. Functional validation of these CzFADs in yeast and cyanobacterial cells revealed that seven are bona fide FAD enzymes with distinct substrates. Combining the validated functions and predicted subcellular compartments of CzFADs and the FA profiles of C. zofingiensis, the FA desaturation pathways in this alga were reconstructed. Furthermore, a multifaceted lipidomic analysis by systematically integrating thin-layer chromatography, gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry techniques was conducted, unraveling profiles of polar membrane lipids in C. zofingiensis and major desaturation steps occurring in these lipids. By correlating transcriptional patterns of CzFAD genes and changes of lipids upon abiotic stress conditions, our results highlighted collaboration of CzFADs for C18 UFA synthesis and supported that both de novo FA synthesis and membrane lipid remodeling contributed C18 UFAs to triacylglycerol for storage. Conclusions Taken together, our study for the first time elucidated the pathways of C18 FA desaturations and comprehensive profiles of polar membrane lipids in C. zofingiensis and shed light on collaboration of CzFADs for the synthesis and enrichment of C18 UFAs in triacylglycerol.

Control of membrane fluidity: the OLE pathway in focus

2017 ◽  
Vol 398 (2) ◽  
pp. 215-228 ◽  
Author(s):  
Stephanie Ballweg ◽  
Robert Ernst
Keyword(s):  
Membrane Fluidity ◽  
Unsaturated Fatty Acids ◽  
De Novo ◽  
Membrane Lipids ◽  
Current Knowledge ◽  
Acyl Chain ◽  
Membrane Integrity ◽  
Building Blocks ◽  
Membrane Lipid ◽  
Membrane Properties

Abstract The maintenance of a fluid lipid bilayer is key for membrane integrity and cell viability. We are only beginning to understand how eukaryotic cells sense and maintain the characteristic lipid compositions and bulk membrane properties of their organelles. One of the key factors determining membrane fluidity and phase behavior is the proportion of saturated and unsaturated acyl chains in membrane lipids. Saccharomyces cerevisiae is an ideal model organism to study the regulation of the lipid acyl chain composition via the OLE pathway. The OLE pathway comprises all steps involved in the regulated mobilization of the transcription factors Mga2 and Spt23 from the endoplasmic reticulum (ER), which then drive the expression of OLE1 in the nucleus. OLE1 encodes for the essential Δ9-fatty acid desaturase Ole1 and is crucial for de novo biosynthesis of unsaturated fatty acids (UFAs) that are used as lipid building blocks. This review summarizes our current knowledge of the OLE pathway, the best-characterized, eukaryotic sense-and-control system regulating membrane lipid saturation, and identifies open questions to indicate future directions.

Membrane lipid metabolism in Chlamydomonas reinhardtii 137+ and Y-1: I. Biochemical localization and characterization of acyltransferase activities

1982 ◽  
Vol 58 (1) ◽  
pp. 469-488
Author(s):  
C.L. Jelsema ◽  
A.S. Michaels ◽  
D.R. Janero ◽  
R.J. Barrnett
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Enzyme Activities ◽  
Membrane Lipids ◽  
Membrane Lipid ◽  
Light Induction ◽  
Wild Type ◽  
Ph Optimum ◽  
Acyltransferase Activity ◽  
Photosynthetic Membranes ◽  
Chloroplast Membrane

The acyltransferases involved in the synthesis of the chloroplast membrane glycerolipids were analysed biochemically in dark-grown and greening Chlamydomonas reinhardtii y-1 as well as in the synchronous wild-type algae (strain 137+) and wild-type membranes. Using oleoyl-CoA as a substrate, three acyltransferase enzyme activities were detected. Glycerol-3-phosphate (glycerol-3-P) acyltransferase exhibited a pH optimum of 8.0 and was inhibited by addition of N-ethylmaleimide (MalNEt). Lysophosphatidate (PtdLys) acyltransferase exhibited a pH optimum of 7.0 and was not affected by the addition of MalNEt. From preliminary analyses, the activity at pH 5.5 appeared to be associated with dihydroxyacetone phosphate acyltransferase activity. Both glycerol-3-P and PtdLys acyltransferases were analysed further and found to be present in dark-grown and light-induced y-1 cells as well as in synchronous 137+ cells and their photosynthetic membranes. Both enzyme activities were enriched at least 10-fold in the photosynthetic membranes of 137+ chloroplasts relative to the activities present in the whole cells. This enrichment is indicative of their intrinsic localization in the thylakoids, suggesting that the photosynthetic membranes exhibit a greater degree of autonomy with respect to the synthesis of their membrane lipids than previously reported. A role for glycerol-3-P and PtdLys acyltransferases in the synthesis of the chloroplast membrane lipids is suggested further by the increases in both enzyme activities coincident with and preceding thylakoid biogenesis following light induction of dark-grown y-1 cells. Increased acyltransferase activity preceded the increase in the chlorophyll content of greening y-1 cells, which is a generally accepted marker for thylakoid synthesis. The increase in the PtdLys acyltransferase activity upon light-induction of the y-1 cells was both more immediate and more dramatic than the increase in glycerol-3-P acyltransferase activity. PtdLys acyltransferase activity was negligible in dark-grown cells and the dramatic increase upon light induction may be important in the subsequent initiation of chloroplast membrane lipid synthesis. On the basis of the localization of acyltransferase enzyme activities to the photosynthetic membranes of 137+ cells and the increase in acyltransferase activity both preceding and occurring in concert with thylakoid synthesis, we propose a direct role for the photosynthetic membranes in the synthesis of their membrane lipid components.

scholarly journals Lipid synthesis in human erythroid cells: the effect of sickling

Blood ◽  
1976 ◽  
Vol 47 (2) ◽  
pp. 189-195
Author(s):  
TA Lane ◽  
SK Ballas ◽  
ER Burka
Keyword(s):  
Cell Membrane ◽  
Neutral Lipid ◽  
Sickle Cell Anemia ◽  
De Novo ◽  
Membrane Lipids ◽  
Membrane Damage ◽  
Lipid Synthesis ◽  
Membrane Lipid ◽  
Erythroid Cell ◽  
Cell Membrane Damage

Human reticulocytes are capable of synthesizing membrane lipids from 14C-glycerol de novo. In both sickle and nonsickle reticulocytes the majority of 14C-glycerol was incorporated into phospholipids, primarily phosphatidylserine and phosphatidylcholine. Incorporation into sphingomyelin was minimal. The most abundant neutral lipid synthesized was triglyceride. In the absence of sickling, the rate of lipid synthesis in sickle reticulocytes was similar to that of nonsickle reticulocytes. With the induction of sickling under anoxic conditions sickle reticulocytes showed a prompt increase in the rate of lipid synthesis to an average of 69% above control values, while nonsickle reticulocytes under similar conditions decreased the rate of lipid synthesis. An increase in the rate of membrane lipid synthesis is associated in the mammalian erythroid cell with cell membrane damage. The findings further confirm that lesions of the erythroid cell membrane in sickle cell anemia are secondary to the sickling process itself.

Arabidopsis 4-COUMAROYL-COA LIGASE 8 contributes to the biosynthesis of the benzenoid ring of coenzyme Q in peroxisomes

2019 ◽  
Vol 476 (22) ◽  
pp. 3521-3532
Author(s):  
Eric Soubeyrand ◽  
Megan Kelly ◽  
Shea A. Keene ◽  
Ann C. Bernert ◽  
Scott Latimer ◽  
...  
Keyword(s):  
Oxidative Metabolism ◽  
Time Course ◽  
Reverse Genetics ◽  
De Novo ◽  
Coenzyme Q ◽  
Control Level ◽  
Wild Type ◽  
Fluorescent Reporters ◽  
Coa Ligase ◽  
Peroxisomal Targeting

Plants have evolved the ability to derive the benzenoid moiety of the respiratory cofactor and antioxidant, ubiquinone (coenzyme Q), either from the β-oxidative metabolism of p-coumarate or from the peroxidative cleavage of kaempferol. Here, isotopic feeding assays, gene co-expression analysis and reverse genetics identified Arabidopsis 4-COUMARATE-COA LIGASE 8 (4-CL8; At5g38120) as a contributor to the β-oxidation of p-coumarate for ubiquinone biosynthesis. The enzyme is part of the same clade (V) of acyl-activating enzymes than At4g19010, a p-coumarate CoA ligase known to play a central role in the conversion of p-coumarate into 4-hydroxybenzoate. A 4-cl8 T-DNA knockout displayed a 20% decrease in ubiquinone content compared with wild-type plants, while 4-CL8 overexpression boosted ubiquinone content up to 150% of the control level. Similarly, the isotopic enrichment of ubiquinone's ring was decreased by 28% in the 4-cl8 knockout as compared with wild-type controls when Phe-[Ring-13C6] was fed to the plants. This metabolic blockage could be bypassed via the exogenous supply of 4-hydroxybenzoate, the product of p-coumarate β-oxidation. Arabidopsis 4-CL8 displays a canonical peroxisomal targeting sequence type 1, and confocal microscopy experiments using fused fluorescent reporters demonstrated that this enzyme is imported into peroxisomes. Time course feeding assays using Phe-[Ring-13C6] in a series of Arabidopsis single and double knockouts blocked in the β-oxidative metabolism of p-coumarate (4-cl8; at4g19010; at4g19010 × 4-cl8), flavonol biosynthesis (flavanone-3-hydroxylase), or both (at4g19010 × flavanone-3-hydroxylase) indicated that continuous high light treatments (500 µE m−2 s−1; 24 h) markedly stimulated the de novo biosynthesis of ubiquinone independently of kaempferol catabolism.

BioMime – A Sirolimus-eluting Coronary Stent System for the Treatment of Patients with De Novo Coronary Lesions – meriT-1 Report

2011 ◽  
Vol 6 (1) ◽  
pp. 39
Author(s):  
Keyword(s):  
Stent Thrombosis ◽  
Time Course ◽  
De Novo ◽  
Drug Eluting Stent ◽  
Cobalt Chromium ◽  
Cardiac Events ◽  
End Points ◽  
Safety And Efficacy ◽  
Binary Restenosis

Background:Since the first reported use of percutaneous transluminal coronary angioplasty, advances in the interventional cardiology arena have been fast paced. Developers and clinicians are adapting from the learning curve awarded by the time-course of drug-eluting stent (DES) evolution. BioMime™ sirolimus-eluting stent (SES) is a step towards biomimicry. The stent is built on a strut of ultra-low thickness (65μm), a cobalt–chromium platform using an intelligent hybrid of closed and open cells allowing for morphology-mediated expansion. It employs a well-known antiproliferative – sirolimus – that elutes from a known biodegradable copolymer formulation within 30 days. The resultant stent demonstrates almost 100% endothelialisation at 30 days in preclinical models.Methods:The meriT-1 was a prospective, single-arm, single-centre trial to evaluate the safety and efficacy of BioMime SES in 30 patients with a single de novo lesion in native coronary arteries. The primary safety and efficacy end-points were major adverse cardiac events (MACE) at 30 days and in-stent late lumen loss at eight months, as measured using quantitative coronary angiographic (QCA) method. Secondary safety and efficacy end-points included MACE at one and two years and angiographic binary restenosis at eight-month angiographic follow-up. Other end-points included the occurrence of stent thrombosis at acute, subacute, late and very late periods and the percentage of diameter stenosis by QCA.Results:No MACE were observed and the median in-stent late luminal loss in 20 (67%) subjects studied by QCA was 0.15mm, with 0% binary restenosis at eight-month follow-up. No stent thrombosis was observed up to one-year follow-up.Conclusions:In comparison to currently available DES, BioMime SES appears to have a considerable scientific basis for prevention of neointimal proliferation, restenosis and associated clinical events.

Time course study of blood pressure in children over a three-year period. Bogalusa Heart Study

Hypertension ◽  
1980 ◽  
Vol 2 (4) ◽  
pp. 102-108 ◽  
Author(s):  
A. W. Voors ◽  
L. S. Webber ◽  
G. S. Berenson
Keyword(s):  
Blood Pressure ◽  
Time Course ◽  
Bogalusa Heart Study ◽  
Heart Study ◽  
Time Course Study
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