Selective arrangement of vesicles on artificial lipid membrane by biotin-avidin interaction

Lipid bilayers suspended over microwells on Si substrates are promising platforms for nanobiodevices that mimic cell membranes. Using the biotin-avidin interaction, we have succeeded in selectively arranging vesicles on the freestanding region of a lipid bilayer. When ternary lipid mixtures of saturated lipid, unsaturated lipid, and cholesterol are used, they separate into liquid-order (Lo) and liquid-crystalline (Lα) domains. A freestanding lipid bilayer prefers the Lα-phase over the Lo-phase because of the difference in their flexibility. In addition, the type of biotinylated lipid determines whether it is localized in the Lα-phase domain or the Lo-phase domain. As a result, the biotinylated unsaturated lipids localized in the Lα-phase domain aggregate in the freestanding lipid bilayer, and vesicles labeled with biotin selectively bind to the freestanding lipid bilayer by the biotin-avidin interaction. This technique helps to introduce biomolecules into the freestanding lipid bilayer of nanobiodevices via vesicles.

An Innovative Prosopis Cineraria Pod Aqueous Waste as Natural Inhibitor for Enhancing Unsaturated Lipids Production in Yeast Cell Using Banana Peel

Single cell oil (SCO) produced by yeast is an attractive alternative due to higher lipid yield in a limited space with naturally manipulating the quality. In the present study, the banana peel is used as a source of carbon for biotransformation by Rhodotorula mucilaginosa to lipid. Further, the quality and quantity of the lipid are enhanced using discarded aqueous Prosopis cinerareia pod extract as a natural inhibitor. P. cineraria aqueous extract was quantified using HPLC, and it was contained phenyl propenoids such as epicatechin (0.068%), gallic acid (0.29%), quercetin (0.34%), epigallocatechin (0.091%), rutin (0.141%), ellagic acid (0.141%), along with glucose (1.22%), and sucrose (2.36%). The sucrose and glucose were isolated from the aqueous extract, and further characterized through NMR and TGA. Hence, this natural inhibitor is found advantageous as compared to the chemical inhibitor (statin) in terms of lipid production with desirable quality. It is achieved by inhibitors blocking the yeast competitive mevalonate pathway to promote higher lipid accumulation in the microbial cells. The anti-chlostrolemic activity of this natural inhibitor might be influenced lipid accumulation by blocking the mevalonate pathway. Thus, the reducing sugars as well as phenylpropenoids were worked in synergy to enhance accumulation of unsaturated lipid in the microbial cells. Phenylpropenoids may inhibit the key enzyme HMG reductase, which controls the mevalonate pathway for ergosterol formation to induce lipid accumulation. This lipid isolation from yeast cell was improved using green solvent viz. liquid-CO2. This lquid-CO2extract was enriched with unsaturated lipid (46.96%) including w-fatty acids such as linoleic (17.61%) and linolenic (5.35%). Thus, the SCO is produced using food waste as the source of carbon as well as an inhibitor, and this lipid is treated as natural to find suitable for nutritional purposes.

Lipid Tails Modulate Antimicrobial Peptide Membrane Incorporation and Activity

Antimicrobial peptides (AMPs) are cationic, amphipathic peptides that interact directly with lipid bilayers. AMPs generally interact with anionic lipid head groups, but it is less clear how the lipid tail length and saturation modulates interactions with membranes. Here, we used native mass spectrometry to measure the stoichiometry of three different AMPs-LL-37, indolicidin, and magainin-2-in lipid nanodiscs. We also measured the activity of these AMPs in large unilamellar vesicle leakage assays. We found that LL-37 formed specific hexamer complexes but with different assembly pathways and affinities that depended on the bilayer thickness. LL-37 was also most active in lipid bilayers containing longer, unsaturated lipids. In contrast, indolicidin incorporated to a higher degree into more fluid lipid bilayers but was more active with thinner, less fluid bilayers. Finally, magainin-2 incorporated to a higher degree into longer, unsaturated bilayers and showed more activity in these same conditions. Together, these data show that higher amounts of peptide incorporation generally led to higher activity and that AMPs tend to incorporate more into longer unsaturated lipid bilayers. However, the activity of AMPs was not always directly related to amount of peptide incorporated.

Elevation of Unsaturated Lipid Species is Accompanied by the Upregulation of Stearoyl-CoA Desaturase in Ovarian Clear Cell Carcinoma

Background Cancer metabolism is associated with enhanced lipogenesis required for rapid growth and proliferation. However, the magnitude of dysregulation of diverse lipid species mostly remain to be characterized, particularly in understudied cancers such as ovarian clear cell carcinoma (OCCC). Further, formalin-fixed paraffin-embedded (FFPE) specimen represent valuable and readily available resources for laboratory investigations but are still underutilized for lipidomics studies. Here we implemented an integrated workflow to investigate lipidomic alterations in OCCC, utilizing FFPE specimen. Methods Lipid extraction of FFPE specimen was carried out by using 1-butanol and methanol in 1:1 (v/v), followed by targeted LC-MS/MS to identify the lipidomic changes in FFPE specimen from OCCC (n=14) as compared to uninvolved contralateral ovarian tissue (n=14). Immunohistochemistry (IHC) assays were implemented to evaluate the expression levels of stearoyl-CoA desaturase (SCD), the rate-limiting enzyme for the synthesis of monounsaturated fatty acids, in OCCC and control tissue specimen. Results We quantified 340 lipid species representing 29 lipid classes. We observed differential regulation of unsaturated lipid species belonging to several glycerophospholipid classes including ether-linked phospholipids, and trihexosylceramide species. We confirmed upregulation of SCD in OCCC by IHC assays. Conclusions By using lipidomic and IHC analysis of archival tissue samples, we were able to provide novel insights into the molecular alterations in OCCC. We show the feasibility of using FFPE specimen to carry out detailed lipidomic analysis of archival cancer samples.

Heat stress elicits remodeling in the anther lipidome of peanut

Understanding the changes in peanut (Arachis hypogaea L.) anther lipidome under heat stress (HT) will aid in understanding the mechanisms of heat tolerance. We profiled the anther lipidome of seven genotypes exposed to ambient temperature (AT) or HT during flowering. Under AT and HT, the lipidome was dominated by phosphatidylcholine (PC), phosphatidylethanolamine (PE), and triacylglycerol (TAG) species (> 50% of total lipids). Of 89 lipid analytes specified by total acyl carbons:total carbon–carbon double bonds, 36:6, 36:5, and 34:3 PC and 34:3 PE (all contain 18:3 fatty acid and decreased under HT) were the most important lipids that differentiated HT from AT. Heat stress caused decreases in unsaturation indices of membrane lipids, primarily due to decreases in highly-unsaturated lipid species that contained 18:3 fatty acids. In parallel, the expression of Fatty Acid Desaturase 3-2 (FAD3-2; converts 18:2 fatty acids to 18:3) decreased under HT for the heat-tolerant genotype SPT 06-07 but not for the susceptible genotype Bailey. Our results suggested that decreasing lipid unsaturation levels by lowering 18:3 fatty-acid amount through reducing FAD3 expression is likely an acclimation mechanism to heat stress in peanut. Thus, genotypes that are more efficient in doing so will be relatively more tolerant to HT.

Thermodynamic Analysis of Myelin Basic Protein Adsorbed on Liquid Crystalline Dioleoylphosphatidylcholine Monolayer

To investigate the stability and dynamic characteristics of monolayer adsorbed on unsaturated lipid dioleoylphosphatidylcholine (DOPC) with varying concentrations of myelin basic protein (MBP), the system is studied by applying Langmuir technique and making atomic force microscope (AFM) observation, which is based on the mass conservation equation analysis method referred to in the thermodynamics theory. As indicated by surface pressure-mean molecular area (π−A) and surface pressure-adsorption time (π−T) isotherms, the physical properties of monolayer derived from the interaction of varying concentrations of MBP with liquid crystalline unsaturated lipid DOPC molecules were qualitatively studied. As revealed by surface morphology analysis with AFM, the micro region was expanded as the concentration of MBP in the subphase was on the increase, suggesting that hydrophobic interactions led to the MBP insertion, thus causing accumulation of the MBP on the surface of the monolayer. Experimental results have demonstrated that the partition coefficient of the interaction between MBP and unsaturated phospholipid DOPC and the molecular area of MBP adsorbed on the monolayer film was calculated using the mass conservation equation. In addition, not only does the varying concentration of MBP in the subphase exerts significant effects on the arrangement and conformation of DOPC monolayer, it also has certain guiding significance to exploring the structural changes to biofilm supramolecular aggregates as well as the pathogenesis and treatment of related diseases.