- Award ID(s):
- 1953975
- NSF-PAR ID:
- 10340670
- Date Published:
- Journal Name:
- Biophysical journal
- ISSN:
- 0006-3495
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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In humans, dietary polyunsaturated fatty acids (PUFAs) are involved in therapeutic processes such as prevention and treatment of cardiovascular diseases, neuropsychiatric disorders, and dementia. We examined the physiology, PUFA accumulation and glycerol lipid biosynthesis in the marine microalga Nannochloropsis salina in response to constant suboptimal temperature (<20 °C). As expected, N. salina exhibited significantly reduced growth rate and photosynthetic activity compared to optimal cultivation temperature. Total fatty acid contents were not significantly elevated at reduced temperatures. Cultures grown at 5 °C had the highest quantity of eicosapentanoic acid (EPA) (C20:5n3) and the lowest growth rate. Additionally, we monitored broadband lipid composition to model the occurrence of metabolic alteration and remodeling for various lipid pools. We focused on triacylglycerol (TAG) with elevated PUFA content. TAGs with EPA at all three acyl positions were higher at a cultivation temperature of 15 °C. Furthermore, monogalactosyldiacylglycerol and digalactosyldiacylglycerol, which are polar lipids associated with chloroplast membranes, decreased with reduced cultivation temperatures. Moreover, gene expression analysis of key genes involved in Kennedy pathway for de novo TAG biosynthesis revealed bimodal variations in transcript level amongst the temperature treatments. Collectively, these results show that Nannochloropsis salina is a promising source of PUFA containing lipids.more » « less
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Stock, Ann M. (Ed.)ABSTRACT Staphylococcus aureus can utilize exogenous fatty acids for phospholipid synthesis. The fatty acid kinase FakA is essential for this utilization by phosphorylating exogenous fatty acids for incorporation into lipids. How FakA impacts the lipid membrane composition is unknown. In this study, we used mass spectrometry to determine the membrane lipid composition and properties of S. aureus in the absence of fakA . We found the fakA mutant to have increased abundance of lipids containing longer acyl chains. Since S. aureus does not synthesize unsaturated fatty acids, we utilized oleic acid (18:1) to track exogenous fatty acid incorporation into lipids. We observed a concentration-dependent incorporation of exogenous fatty acids into the membrane that required FakA. We also tested how FakA and exogenous fatty acids impact membrane-related physiology and identified changes in membrane potential, cellular respiration, and membrane fluidity. To mimic the host environment, we characterized the lipid composition of wild-type and fakA mutant bacteria grown in mouse skin homogenate. We show that wild-type S. aureus can incorporate exogenous unsaturated fatty acids from host tissue, highlighting the importance of FakA in the presence of host skin tissue. In conclusion, FakA is important for maintaining the composition and properties of the phospholipid membrane in the presence of exogenous fatty acids, impacting overall cell physiology. IMPORTANCE Environmental fatty acids can be harvested to supplement endogenous fatty acid synthesis to produce membranes and circumvent fatty acid biosynthesis inhibitors. However, how the inability to use these fatty acids impacts lipids is unclear. Our results reveal lipid composition changes in response to fatty acid addition and when S. aureus is unable to activate fatty acids through FakA. We identify concentration-dependent utilization of oleic acid that, when combined with previous work, provides evidence that fatty acids can serve as a signal to S. aureus . Furthermore, using mouse skin homogenates as a surrogate for in vivo conditions, we showed that S. aureus can incorporate host fatty acids. This study highlights how exogenous fatty acids impact bacterial membrane composition and function.more » « less
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Scope Long‐chain (LC)‐PUFAs act as precursors for the special class of retinal lipids known as very‐long‐chain (VLC)‐PUFAs and the effect of diabetes on retinal VLC‐PUFA levels is unexplored. In order to understand the supplemental effect of omega‐3 (n‐3) LC‐PUFAs on decreasing levels of VLC‐PUFAs due to diabetes, Nile rats, which develop diabetes spontaneously, and Akita mouse, a genetic diabetes model, are chosen.
Methods and results Human retinal punches from donors are collected from an eye bank; lipids are extracted and analyzed to study the alterations in VLC‐PUFAs and their omega‐3/omega‐6 (n‐3/n‐6) ratios. Nile rats are fed a high‐fat diet to induce hyperglycemia, and then an n‐3 PUFA‐rich diet is fed to the experimental group for 2 months. Diabetic male Akita mice and WT mice are fed with 5% fish‐oil mixed in with their chow for 2 months to observe the effect of n‐3 PUFAs. Results indicate that VLC‐PUFA levels are lower in human diabetic and retinopathic retinal punches compared to age‐matched controls. With supplementation of n‐3 PUFAs, there is a significant increase in n‐3/n‐6 VLC‐PUFA ratios in both animal models compared to diabetic controls.
Conclusion Dietary supplementation with n‐3 LC‐PUFAs helps to prevent progression of diabetes and associated retinopathy.
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