Interrelationships between fatty acid biosynthesis and acyl-lipid synthesis in Chlorella vulgaris

Abstract

1. Fatty acid synthesis from [2-(14)C]acetate by Chlorella vulgaris cells grown and incubated in the dark is limited almost entirely to the production of saturated and monoenoic acids. 2. In light-incubated cells, both saturated and polyunsaturated fatty acids are rapidly synthesized. 3. Two groups of lipids can be distinguished in both dark- and light-incubated cells. The first group, consisting of phosphatidyl-glycerol, monogalactosyl diglyceride, lecithin and neutral glyceride, has a very high turnover rate for certain fatty acids. The second group, consisting of digalactosyl diglyceride, sulpholipid, phosphatidylethanolamine and phosphatidylinositol, has a slow turnover of fatty acids. 4. The lipids with rapid fatty acid turnover may be involved in the sequences of saturated and unsaturated fatty acid synthesis. A classification of lipids is made on the basis of their suggested functions.

The Mechanism of Formation of Polyunsaturated Fatty Acids by Photosynthetic Tissue

“…The observations of Nichols et al [7] and Nichols [8] had already led to a tentative hypothesis about the way in which polar lipids might be involved in desaturation, so that the quite striking association of phosphatidyl choline labelling with conversion of oleate into linoleate now encouraged us to try to investigate the possible mechanism of this involvement. A precedent already existed for the idea that a complex lipid could be the subtrate for a fatty acids transformation in Law's work [14] on the involvement of phosphatidyl ethanolamine in the cyclopropane fatty acid synthetase-catalysed reaction.…”

“…The work of Nagai and Bloch [6] with the stearoylacyl carrier protein desaturase of Euglena gracilis might suggest that the acyl carrier protein ester is the true substrate. However, the experiments of Nichols and James [7,8] have pointed to the possibility that phospholipids and glycolipids may have an important role to play in fatty acid transformations, while, more specifically, Harris et al 141 have speculated about the possibility that phosphatidyl choline, which has a striklingly high specific activity with respect to newly biosynthesized linoleate in Chlorelh, may have special importance for the desaturation reaction.I n this paper, we shall report further studies which confirm that phosphatidyl choline is an important intermediate in the conversion of oleate into linoleate. …”

Genome-Scale Metabolic Model for the Green Alga Chlorella vulgaris UTEX 395 Accurately Predicts Phenotypes under Autotrophic, Heterotrophic, and Mixotrophic Growth Conditions

“…The metabolic model encompasses pathways to synthesize each of these lipids. Using the experimentally determined fatty acid values, a theoretical categorization of the groups of lipids was conducted according to a previous study (Nichols et al, 1967). The abundances of the groups of metabolites defined in the BOF are shown in Figure 1D.…”

“…The quantified fatty acids were spread out according to previously reported lipid profiles (Nichols et al, 1967). The relation of nucleotide composition (28 RNA/DNA) was taken from Muthuraj et al (2013).…”

“…Literature and experimental data were normalized assuming an idealized size and weight for C. vulgaris (see below). The specific starch production and degradation rates were calculated from the experimental data, and the curves were adjusted to the Gompertz model using Kaleidagraph (Synergy Software; Nichols et al, 1967;Wang and Zuidhof, 2004).…”