Surface Chemistry Study of the Interactions of Sesame Oil with Meibomian Films

A possible approach for the treatment of meibomian gland disease (MGD) can be the supplementation of meibomian gland secretion (MGS) with nonpolar lipids (NPL) rich plant oils. Sesame oil (SO), approximately equal in monounsaturated fat (oleic acid, 40% of total) and polyunsaturated fat (linoleic acid, 42% of total), has shown multiple health benefits due to its anti-inflammatory and antioxidant effects. Thus, the interactions between SO and MGS in surface layers deserve further study. Therefore, pseudobinary films were formed with controlled MGS/SO molar ratios (0%, 10%, 30%, 50%, and 100% SO) at the air/water surface of the Langmuir trough over phosphate buffered saline (pH 7.4) subphase. Surface pressure (π)-area (A) isotherms and Brewster angle microscopy observations showed nonideal interactions where SO aggregates with MGS and complements the NPL stratum of the meibomian layers. The analysis of stress relaxation transients with Kohlrausch–Williams–Watts equation revealed that the supplementation of fixed amount of MGS with excess lipids via SO altered the dilatational elasticity of the films as reflected by the increase of the exponent β. Thus, SO with its unique combination of high oxidative stability and abundance of long polyunsaturated acyl chains might be a useful supplement to MGS layers.

The role of lipid droplets in microbial pathogenesis

The nonpolar lipids present in cells are mainly triacylglycerols and steryl esters. When cells are provided with an abundance of nutrients, these storage lipids accumulate. As large quantities of nonpolar lipids cannot be integrated into membranes, they are isolated from the cytosolic environment in lipid droplets. As specialized, inducible cytoplasmic organelles, lipid droplets have functions beyond the regulation of lipid metabolism, in cell signalling and activation, membrane trafficking and control of inflammatory mediator synthesis and secretion. Pathogens, including fungi, viruses, parasites, or intracellular bacteria can induce and may benefit from lipid droplets in infected cells. Here we review biogenesis of lipid droplets as well as the role of lipid droplets in the pathogenesis of selected viruses, bacteria, protists and yeasts.

60 High lipid exposure during invitro maturation alters the lipid profile of bovine oocyte and benefits blastocyst development

Lipid metabolism provides a potent source of energy and has an important role in the acquisition of oocyte competence. However, there are conflicting reports about how lipid exposure during invitro maturation (IVM) impacts the gamete and further embryo development. In this study, we performed IVM of oocytes in the presence of lipid-rich culture media and used a broad lipid screening to accurately map the impact on the lipid profile and developmental potential. For that, nonpolar lipids were extracted from fetal bovine serum (FBS) with organic solvents (Bligh-Dyer method) and then used to supplement IVM medium (TCM-199 bicarbonate+10% FBS, hormones, pyruvate and antibiotics). COCs obtained from abattoir ovaries were submitted to IVM (4 biological replicates) in 2 groups: OC (control; IVM medium) and OHL (high lipid; IVM medium supplemented with extra 10% FBS nonpolar lipids). After 24h, we collected mature oocytes and those remaining followed to IVF and then to IVC (synthetic oviductal fluid with amino acids, SOFaa, with 5% FBS) for 7 days at 38.5°C, 20% O2, and 5% CO2 in air in high humidity. Expanded blastocysts were collected (BC and BHL) and blastocyst rates were assessed. Lipid extracts of individual oocytes and embryos (n=10/group) were analysed by multiple reaction monitoring (MRM)-profiling mass spectrometry. A total of 379 lipids from 10 classes were investigated [triacylglycerol (TAG), cholesteryl esters (CE), free fatty acids (FFA), acyl-carnitine, sphingomyelin (SM) and phospholipids derived from choline (PC), ethanolamine (PE), glycerol (PG), serine (PS), and inositol (PI)]. Exploratory data analysis was performed by principal component analysis (PCA; Metaboanalyst 4.0), and fold-change (FC) values were calculated based on the relative intensity of lipid ions (FC > 2 and P<0.05). IVC rates were compared by t-test (α=5%). PCA revealed a clear distinction in the lipid content for both oocytes and blastocysts (control vs. treated). More specifically, there was 2-fold enrichment for total TAG and CE in control groups and a 1.5-fold enrichment for total FFA in the treated groups at the oocyte and the blastocyst stages. Surprisingly, the average blastocyst rate was higher in the group derived from oocytes exposed to a high-lipid environment (41.56±7.73 vs. 22.62±1.67; P=0.003), which led us to investigate specific lipid ions. Groups OHL and BHL had increased contents of structural and signalling phospholipids (PC, SM, PE, and PS) and up to 3 times more oleic and linoleic acids, which have been associated with improved oocyte maturation and blastocyst development. Here, we demonstrate how distinct lipid exposures during IVM can robustly alter the lipid profile of oocytes. But more interestingly, it is clear that these are long-term effects, still observed at the blastocyst stage. More studies are required to verify the metabolic impact of this alternative lipid supplementation; however, these results indicate that high lipid exposure is not necessarily detrimental and, at a certain point, may even counteract lipid accumulation commonly observed during invitro embryo production.

Regulation of the yeast triacylglycerol lipases Tgl4p and Tgl5p by the presence/absence of nonpolar lipids

Tgl3p, Tgl4p, and Tgl5p are the major triacylglycerol lipases of the yeast Saccharomyces cerevisiae. Recently we demonstrated that properties of Tgl3p are regulated by the formation of nonpolar lipids. The present study extends these investigations to the two other yeast triacylglycerol lipases, Tgl4p and Tgl5p. We show that Tgl4p and Tgl5p, which are localized to lipid droplets in wild type, are partially retained in the endoplasmic reticulum in cells lacking triacylglycerols and localize exclusively to the endoplasmic reticulum in a mutant devoid of lipid droplets. In cells lacking steryl esters, the subcellular distribution of Tgl4p and Tgl5p is unaffected, but Tgl5p becomes unstable, whereas the stability of Tgl4p increases. In cells lacking nonpolar lipids, Tgl4p and Tgl5p lose their lipolytic activity but retain their side activity as lysophospholipid acyltransferases. To investigate the regulatory network of yeast triacylglycerol lipases in more detail, we also examined properties of Tgl3p, Tgl4p, and Tgl5p, respectively, in the absence of the other lipases. Surprisingly, lack of two lipases did not affect expression, localization, and stability of the remaining Tgl protein. These results suggest that Tgl3p, Tgl4p, and Tgl5p, although they exhibit similar functions, act as independent entities.