Fatty acids in microalgae and cyanobacteria in a changing world: Contrasting temperate and cold environments

Abstract To explore the contribution of ω-3 fatty acid desaturases (FADs) to cold stress response in a special cryophyte, Chorispora bungeana (C. bungeana), two plastidial ω-3 FAD genes (CbFAD7 and CbFAD8) were cloned and verified in a Arabidopsis fad7fad8 mutant, before being compared with the microsomal ω-3 FAD gene (CbFAD3) on expression profile. Though these genes were expressed in all tested tissues of C. bungeana, CbFAD7 and CbFAD8 have the highest expression in leaves, while CbFAD3 was mostly expressed in non-green tissues. Low temperatures (4, 0 and -4 ℃) resulted in significant increases in trienoic fatty acids (TAs, mainly C18:3), which were consistent with the non-redundant expression of CbFAD3 and CbFAD8 in suspension-cultured cells, and the coordination of CbFAD7 and CbFAD8 in leaves. Furthermore, the contribution of CbFAD8 increased as temperature decrease in the two tissues. Our data revealed that jasmonie acid and brassinosteroids participated in the cold-responsive expression of these genes in both tissues, and the pyhtohormone regulation in leaves was more complicated with the participation of abscisic acid and gibberellin. These results point to the hormone-regulated non-redundant contribution of ω-3 CbFADs to maintain appropriate level of TAs under low temperatures, which help C. bungeana survive in cold environments.

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Reconstruction of the Fatty Acid Biosynthetic Pathway ofExiguobacterium antarcticumB7 Based on Genomic and Bibliomic Data

BioMed Research International ◽

10.1155/2016/7863706 ◽

2016 ◽

Vol 2016 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Regiane Kawasaki ◽

Rafael A. Baraúna ◽

Artur Silva ◽

Marta S. P. Carepo ◽

Rui Oliveira ◽

...

Keyword(s):

Fatty Acids ◽

Fatty Acid ◽

Fatty Acid Biosynthesis ◽

De Novo ◽

Short Chain Fatty Acids ◽

Hexadecenoic Acid ◽

Biosynthesis Pathway ◽

Acid Biosynthesis ◽

Cold Environments ◽

Fatty Acid Biosynthesis Pathway

Exiguobacterium antarcticumB7 is extremophile Gram-positive bacteria able to survive in cold environments. A key factor to understanding cold adaptation processes is related to the modification of fatty acids composing the cell membranes of psychrotrophic bacteria. In our study we show thein silicoreconstruction of the fatty acid biosynthesis pathway ofE. antarcticumB7. To build the stoichiometric model, a semiautomatic procedure was applied, which integrates genome information using KEGG and RAST/SEED. Constraint-based methods, namely, Flux Balance Analysis (FBA) and elementary modes (EM), were applied. FBA was implemented in the sense of hexadecenoic acid production maximization. To evaluate the influence of the gene expression in the fluxome analysis, FBA was also calculated using thelog2⁡FCvalues obtained in the transcriptome analysis at 0°C and 37°C. The fatty acid biosynthesis pathway showed a total of 13 elementary flux modes, four of which showed routes for the production of hexadecenoic acid. The reconstructed pathway demonstrated the capacity ofE. antarcticumB7 tode novoproduce fatty acid molecules. Under the influence of the transcriptome, the fluxome was altered, promoting the production of short-chain fatty acids. The calculated models contribute to better understanding of the bacterial adaptation at cold environments.

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Lipid compositional correlates of temperature-adaptive interspecific differences in membrane physical structure

Journal of Experimental Biology ◽

10.1242/jeb.203.14.2105 ◽

2000 ◽

Vol 203 (14) ◽

pp. 2105-2115 ◽

Cited By ~ 17

Author(s):

J.A. Logue ◽

A.L. de Vries ◽

E. Fodor ◽

A.R. Cossins

Keyword(s):

Fatty Acids ◽

Fatty Acid Composition ◽

Fatty Acid ◽

Fluorescence Anisotropy ◽

Unsaturated Fatty Acids ◽

Physical Structure ◽

Synaptic Membranes ◽

Teleost Species ◽

Cold Environments ◽

Interspecific Differences

Teleost species from cold environments possess more disordered brain synaptic membranes than species from warm habitats, thereby providing equivalent physical structures at their respective habitat temperatures. We have related this adaptive interspecific biophysical response to the fatty acid composition of brain membranes from 17 teleost species obtained from Antarctic, temperate and semi-tropical waters, as well as from rat and turkey as representative homeotherms. Cold-adaptive increases in membrane disorder (determined by fluorescence anisotropy with diphenylhexatriene as probe) were correlated with large and linear increases in the proportion of unsaturated fatty acids, from 35 to 60 % in phosphatidylcholine (PtdCho) and from 55 to 85 % in phosphatidylethanolamine (PtdEth). For PtdCho, the cold-adaptive increase in unsaturation was associated almost entirely with increased proportions (from 7 to 40 %) of polyunsaturated fatty acids (PUFAs), with mono-unsaturates (MUFAs) providing an approximately constant proportion in all species. Exactly opposite effects were evident for phosphatidylethanolamine (PtdEth). Thus, the compositional adaptation for PtdCho occurred largely by exchange of polyunsaturated and mono-unsaturated fatty acid in the sn-2 position, whilst for PtdEth it involved exchanges between saturates and mono-unsaturates at the sn-1 position. This difference may be related to the different molecular shapes of the two phosphoglycerides and the need to maintain the balance between bilayer-stabilising and -destabilising tendencies. This comparative study provides a more comprehensive view of the compositional adjustments that accompany and perhaps account for temperature-adaptive interspecific differences in membrane physical structure.

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