Improved productivity and oxidative stress tolerance under nitrogen starvation is associated with the ablated Δ5 desaturation in the green microalga Lobosphaera incisa

Pal‐Nath, Dipasmita; Didi‐Cohen, Shoshana; Shtaida, Nastassia; Nath, Pulak; Samani, Talya; Boussiba, Sammy; Khozin‐Goldberg, Inna

doi:10.1016/j.algal.2017.06.026

Cited by 17 publications

(20 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The cultures of L. incisa mutant strain P127 were grown in 1-L glass columns bubbled with 1.5% CO 2 in nutrient-replete mBG11 medium for 3 d. Cells were harvested by centrifugation and resuspended at a biomass density of 1 mg mL −1 in an n -depleted mBG11 medium to induce N starvation. Cultures were then cultivated under a light intensity of 170 μmol photons m −2 s −1 for 14 d [ 24 ]. The fatty acid profile and dry weight content were regularly examined.…”

Section: Methodsmentioning

confidence: 99%

“…The delta-5 desaturase mutant of L. incisa P127, deficient in ARA, represents a prospective oleaginous organism for the photosynthesis-driven biotechnological production of DGLA for dietary and medicinal applications [ 7 , 23 ]. It accumulates up to 30% of DGLA in storage lipids, triacylglycerols, under nitrogen starvation conditions [ 24 ].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

DGLA from the Microalga Lobosphaera Incsa P127 Modulates Inflammatory Response, Inhibits iNOS Expression and Alleviates NO Secretion in RAW264.7 Murine Macrophages

et al. 2020

Self Cite

View full text Add to dashboard Cite

Microalgae have been considered as a renewable source of nutritional, cosmetic and pharmaceutical compounds. The ability to produce health-beneficial long-chain polyunsaturated fatty acids (LC-PUFA) is of high interest. LC-PUFA and their metabolic lipid mediators, modulate key inflammatory pathways in numerous models. In particular, the metabolism of arachidonic acid under inflammatory challenge influences the immune reactivity of macrophages. However, less is known about another omega-6 LC-PUFA, dihomo-γ-linolenic acid (DGLA), which exhibits potent anti-inflammatory activities, which contrast with its delta-5 desaturase product, arachidonic acid (ARA). In this work, we examined whether administrating DGLA would modulate the inflammatory response in the RAW264.7 murine macrophage cell line. DGLA was applied for 24 h in the forms of carboxylic (free) acid, ethyl ester, and ethyl esters obtained from the DGLA-accumulating delta-5 desaturase mutant strain P127 of the green microalga Lobosphaera incisa. DGLA induced a dose-dependent increase in the RAW264.7 cells’ basal secretion of the prostaglandin PGE1. Upon bacterial lipopolysaccharide (LPS) stimuli, the enhanced production of pro-inflammatory cytokines, tumor necrosis factor alpha (TNFα) and interleukin 1β (IL-1β), was affected little by DGLA, while interleukin 6 (IL-6), nitric oxide, and total reactive oxygen species (ROS) decreased significantly. DGLA administered at 100 µM in all forms attenuated the LPS-induced expression of the key inflammatory genes in a concerted manner, in particular iNOS, IL-6, and LxR, in the form of free acid. PGE1 was the major prostaglandin detected in DGLA-supplemented culture supernatants, whose production prevailed over ARA-derived PGE2 and PGD2, which were less affected by LPS-stimulation compared with the vehicle control. An overall pattern of change indicated DGLA’s induced alleviation of the inflammatory state. Finally, our results indicate that microalgae-derived, DGLA-enriched ethyl esters (30%) exhibited similar activities to DGLA ethyl esters, strengthening the potential of this microalga as a potent source of this rare anti-inflammatory fatty acid.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

DGLA from the Microalga Lobosphaera Incsa P127 Modulates Inflammatory Response, Inhibits iNOS Expression and Alleviates NO Secretion in RAW264.7 Murine Macrophages

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…Fatty acid composition and content were determined following direct transmethylation of freeze-dried biomass and isolated TAG in dry methanol containing 2% (v/v) sulfuric acid at 80°C for 1.5 h under an argon atmosphere, using heptadecanoic acid 17:0 as an internal standard. Fatty acid methyl esters (FAME) were resolved by gas chromatography on a Trace GC ultra (Thermo Fisher Scientific, Milan, Italy) equipped with a flame-ionization detector (FID;Pal-Nath et al, 2017).…”

Section: Determination Of Fatty Acid Composition and Contentmentioning

confidence: 99%

Lipidome Remodeling and Autophagic Respose in the Arachidonic-Acid-Rich Microalga Lobosphaera incisa Under Nitrogen and Phosphorous Deprivation

et al. 2020

Self Cite

View full text Add to dashboard Cite

The green microalga Lobosphaera incisa accumulates triacylglycerols (TAGs) with exceptionally high levels of long-chain polyunsaturated fatty acid (LC-PUFA) arachidonic acid (ARA) under nitrogen (N) deprivation. Phosphorous (P) deprivation induces milder changes in fatty acid composition, cell ultrastructure, and growth performance. We hypothesized that the resource-demanding biosynthesis and sequestration of ARA-rich TAG in lipid droplets (LDs) are associated with the enhancement of catabolic processes, including membrane lipid turnover and autophagic activity. Although this work focuses mainly on N deprivation, a comparative analysis of N and P deprivation responses is included. The results of lipidomic profiling showed a differential impact of N and P deprivation on the reorganization of glycerolipids. The formation of TAG under N deprivation was associated with the enhanced breakdown of chloroplast glycerolipids and the formation of lyso-lipids. N-deprived cells displayed a profound reorganization of cell ultrastructure, including internalization of cellular material into autophagic vacuoles, concomitant with the formation of LDs, while P-deprived cells showed better cellular ultrastructural integrity. The expression of the hallmark autophagy protein ATG8 and the major lipid droplet protein (MLDP) genes were coordinately upregulated, but to different extents under either N or P deprivation. The expression of the Δ5-desaturase gene, involved in the final step of ARA biosynthesis, was coordinated with ATG8 and MLDP, exclusively under N deprivation. Concanamycin A, the inhibitor of vacuolar proteolysis and autophagic flux, suppressed growth and enhanced levels of ATG8 and TAG in N-replete cells. The proportions of ARA in TAG decreased with a concomitant increase in oleic acid under both N-replete and N-deprived conditions. The photosynthetic apparatus’s recovery from N deprivation was impaired in the presence of the inhibitor, along with the delayed LD degradation. The GFP-ATG8 processing assay showed the release of free GFP in N-replete and N-deprived cells, supporting the existence of autophagic flux. This study provides the first insight into the homeostatic role of autophagy in L. incisa and points to a possible metabolic link between autophagy and ARA-rich TAG biosynthesis.

show abstract

“…In Lobosphaera incisa , the genes encoding antioxidant enzymes, such as glutathione peroxidases, catalases, and superoxide dismutases, are highly expressed in the green vegetative cells (Pal‐Nath et al. ). In contrast, the expression of these genes is reduced under nitrogen starvation conditions (Pal‐Nath et al.…”

Section: Discussionmentioning

confidence: 99%

“…In contrast, the expression of these genes is reduced under nitrogen starvation conditions (Pal‐Nath et al. ), and the levels of the ROS‐protective molecules are reduced (Kokabi et al. ).…”

Section: Discussionmentioning

confidence: 99%

Resilience to Freezing in the Vegetative Cells of the Microalga Lobosphaera incisa (Trebouxiophyceae, Chlorophyta)

Kugler

Kumari

Kokabi

et al. 2020

Journal of Phycology

Self Cite

View full text Add to dashboard Cite

The chlorophyte microalga Lobosphaera incisa was isolated from the snowy slopes of Mt. Tateyama in Japan. This microalga stores exceptionally high amounts of the omega‐6 LC‐PUFA arachidonic acid in triacylglycerols, and therefore represents a potent photosynthetic source for this essential LC‐PUFA. Assuming that freezing tolerance may play a role in adaptation of L. incisa to specific ecological niches, we examined the capability of L. incisa to tolerate extreme sub‐zero temperatures. We report here, that the vegetative cells of L. incisa survived freezing at −20°C and −80°C (over 1 month), without cryoprotective agents or prior treatments. Cells successfully recovered upon thawing and proliferated under optimal growth conditions (25°C). However, cells frozen at −80°C showed better recovery and lower cellular ROS generation upon thawing, compared to those preserved at −20°C. Photosynthetic yield of PSII, estimated by Fv/Fm, temporarily decreased at day 1 post freezing and resumed to the original level at day 3. Interestingly, the thawed algal cultures produced a higher level of chlorophylls, exceeding the control culture. The polar metabolome of the vegetative cells comprised a range of compatible solutes, dominated by glutamate, sucrose, and proline. We posit that the presence of endogenous cryoprotectants, a rigid multilayer cell wall, the high LC‐PUFA content in membrane lipids, and putative cold‐responsive proteins may contribute to the retention of functionality upon recovery from the frozen state, and therefore for the survival under cryospheric conditions. From the applied perspective, this beneficial property holds promise for the cryopreservation of starter cultures for research and commercial purposes.

show abstract

Improved productivity and oxidative stress tolerance under nitrogen starvation is associated with the ablated Δ5 desaturation in the green microalga Lobosphaera incisa

Cited by 17 publications

References 64 publications

DGLA from the Microalga Lobosphaera Incsa P127 Modulates Inflammatory Response, Inhibits iNOS Expression and Alleviates NO Secretion in RAW264.7 Murine Macrophages

DGLA from the Microalga Lobosphaera Incsa P127 Modulates Inflammatory Response, Inhibits iNOS Expression and Alleviates NO Secretion in RAW264.7 Murine Macrophages

Lipidome Remodeling and Autophagic Respose in the Arachidonic-Acid-Rich Microalga Lobosphaera incisa Under Nitrogen and Phosphorous Deprivation

Resilience to Freezing in the Vegetative Cells of the Microalga Lobosphaera incisa (Trebouxiophyceae, Chlorophyta)

Contact Info

Product

Resources

About