Rapid and comprehensive evaluation of microalgal fatty acids via untargeted gas chromatography and time‐of‐flight mass spectrometry

Due to their high triacylglyceride content, microalgae are intensively investigated for bio‐economy and food applications. However, lipid analysis is a laborious task incorporating extraction, transesterification and typically gas chromatographic measurement. Co‐elution induces a significant risk of fatty acid misidentification and thus, additional purification steps like thin layer chromatography are needed. Contrary to database matching approaches, solely targeted analysis is facilitated as compound identification is driven by matching retention times or indices with standard substances. In this context, a rapid workflow for the analysis of algal fatty acids is presented. In‐situ transesterification was used to simplify sample preparation and conditions were optimized towards fast processing. If results are needed at the very day of sampling, direct processing without a preceding drying step is feasible to obtain a rough estimate about the occurrence of the major compounds. Coupling gas chromatography and time‐of‐flight mass spectrometry enables untargeted analysis. Unknown compounds may be identified by structural reconstruction of their respective fragmentation patterns and by database matching to routinely avoid mismatches by co‐elution of disturbing agents. The developed workflow was successfully applied to derive the exact stereochemistry of all fatty acids from Chlorella vulgaris and a systematic shift depending on physiological state of the cells was confirmed.     

About paired correlation of π-electrons in tissue lipid extracts of animals of different evolutionary levels

With aid of optical methods, the presence of the paired correlations of π-electrons has been revealed in phospholipids as well as in triacylglyceride molecules. Used for analysis were lipid extracts of individual representatives of animals of various evolutionary levels—cartilaginous and bony fish and mammals differing by the content of unsaturated fatty acids in lipids. It has been established that the necessary condition for formation of electron pairs is interaction of lipid molecules with each other. An opinion is put forward that in the liquid crystal structure of the membrane monolayer there are two zones able to form electron pairs—the zone of location of ester bonds and the zone in the region of double bonds. Besides, the paired correlation in the phospholipid molecule electron system is accompanied by the absence of electric resistance of the membrane monolayer, which provides the monolayer superconductivity at low rates of movements of the “electron fluid.” It is to be noted that the very fact of the presence of the electron pair implies transfer of energy by small portions, which does not allow excitation of individual phospholipid molecules in the monolayer and promotes stability of the native membrane. Our data agree with the known statement of A. Pulman and B. Pulman that the life dynamicity is determined by dynamicity of the electron cloud in coupled or partially coupled systems.     

The important role of stratum corneum lipids for the cutaneous barrier function

The skin protects the body from unwanted influences from the environment as well as excessive water loss. The barrier function of the skin is located in the stratum corneum (SC). The SC consists of corneocytes embedded in a lipid matrix. This lipid matrix is crucial for the lipid skin barrier function. This paper provides an overview of the reported SC lipid composition and organization mainly focusing on healthy and diseased human skin. In addition, an overview is provided on the data describing the relation between lipid modulations and the impaired skin barrier function. Finally, the use of in vitro lipid models for a better understanding of the relation between the lipid composition, lipid organization and skin lipid barrier is discussed. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias.     

Corticosteroid-binding globulin synthesis and distribution in rat white adipose tissue

The lactone isolated from Fusarium termed L659,699 is a potent specific inhibitor of the enzyme 3hydroxi3methylglutaril coenzyme A (HMG-CoA) synthase. In cultures of smooth muscle cells (SMC) isolated from aortic-arch of control (CSMC) and 5% of cholesterol diet (Ch-SMC) treated chicks, the incorporation of (¹⁴C)acetate to lipids (cholesterol, triacylglycerides and cholesterol ester) were greater in ChSMC cultures than in CSMC and the presence of 0.05 M L659,699 for 2 h in the incubation medium decrease the synthesis of cholesterol however the triacylglycerides synthesis increase. The effect of inhibitor is stronger in young cultures (3–4 steps) than in the older ones (11–12 steps). In young CSMC and ChSMC cultures the inhibition of cholesterol and triacylglycerides synthesis by L659,699 was reversal.     

Lipase immobilized on hydrophobic porous polymer supports prepared by concentrated emulsion polymerization and their activity in the hydrolysis of triacylglycerides

Microporous polymer supports for the immobilization of lipase have been prepared by the polymerization of a concentrated emulsion precursor. The concentrated emulsion consists of a mixture of styrene and divinyl-benzene containing a suitable surfactant and an initiator as the continuous phase and water as the dispersed phase. The volume fraction of the latter phase was greater than 0.74, which is the volume fraction of the dispersed phase for the most compact arrangement of spheres of equal radius. The lipase from Candida rugosa has been immobilized on the internal surface of the hydrophobic microporous poly(styrene-divinyl benzene) supports and used as biocatalysts for the hydrolysis of triacylglycerides. The effects of the amount of surfactant, of the molar ratio of divinylbenzene/styrene in the continuous phase, and of the aquaphilicity of the supports on the adsorption, activity, and stability of the immobilized lipase have been investigated. The microporous poly(styrene-divinylbenzene) adsorbents constitute excellent supports for lipase because both the amount adsorbed is large and the rate of enzymatic reaction per molecule of lipase is higher for the immobilized enzyme than for the free one. (c) 1993 John Wiley & Sons, Inc.     

ACCLIMATION OF PROROCENTRUM MINIMUM (DINOPHYCEAE) TO PROLONGED DARKNESS BY USE OF AN ALTERNATIVE CARBON SOURCE FROM TRIACYLGLYCERIDES AND GALACTOLIPIDS

The dinoflagellate Prorocentrum minimum (Pavillard) Schiller is known to be a major bloom-causing microalga in the southern ocean of the Korean peninsula. The acclimation of this alga to darkness for 10 days was investigated by analyzing the content of various lipids, such as phospholipid (PL), galactolipid (GL), and triacylglyceride (TAG). Actively growing cultures of the alga under normal growth conditions (14:10 h LD [light:dark] cycle) were transferred to a growth chamber under conditions of no light and no carbon sources in the medium, and the culture was continued for another 10 days. The results showed that the content of TAG and GL decreased gradually during dark incubation, whereas the total PL content changed little; PC, PE, and PG decreased; and PS, PA, and PI increased. An increase in the activity of β-oxidation and isocitrate lyase (ICL, a glyoxylate cycle enzyme) paralleled the decrease of TAG and GL. These observations strongly suggested that TAG and GL were utilized as alternative carbon sources by the cells under the prolonged dark cultivation. Light treatment of the cells cultivated in the dark for 10 days allowed them to attain the lipid composition that was observed in cells grown in light. These results strongly suggested that the cells maintained their metabolic integrity without unrecoverable cellular damages or cell death during 10 days of dark cultivation.     

Fatty acid synthase plays a role in cancer metabolism beyond providing fatty acids for phospholipid synthesis or sustaining elevations in glycolytic activity

Fatty acid synthase is over-expressed in many cancers and its activity is required for cancer cell survival, but the role of endogenously synthesized fatty acids in cancer is unknown. It has been suggested that endogenous fatty acid synthesis is either needed to support the growth of rapidly dividing cells, or to maintain elevated glycolysis (the Warburg effect) that is characteristic of cancer cells. Here, we investigate both hypotheses. First, we compared utilization of fatty acids synthesized endogenously from ¹⁴C-labeled acetate to those supplied exogenously as ¹⁴C-labeled palmitate in the culture medium in human breast cancer (MCF-7 and MDA-MB-231) and untransformed breast epithelial cells (MCF-10A). We found that cancer cells do not produce fatty acids that are different from those derived from exogenous palmitate, that these fatty acids are esterified to the same lipid and phospholipid classes in the same proportions, and that their distribution within neutral lipids is not different from untransformed cells. These results suggest that endogenously synthesized fatty acids do not fulfill a specific function in cancer cells. Furthermore, we observed that cancer cells excrete endogenously synthesized fatty acids, suggesting that they are produced in excess of requirements. We next investigated whether lipogenic activity is involved in the maintenance of high glycolytic activity by culturing both cancer and non-transformed cells under anoxic conditions. Although anoxia increased glycolysis 2–3 fold, we observed no concomitant increase in lipogenesis. Our results indicate that breast cancer cells do not have a specific qualitative or quantitative requirement for endogenously synthesized fatty acids and that increased de novo lipogenesis is not required to sustain elevations in glycolytic activity induced by anoxia in these cells.