Branka Blagović

Cell lipids of the Candida lipolytica yeast grown on methanol

Candida lipolytica yeast, grown on 1% methanol as the only carbon and energy source, synthesized 4.9% of dry cell mass as lipids, 52.3% of which were polar lipids. Polar lipids consisted mainly of phospholipids and sphingolipids as their minor components. The total long-chain bases content has been found to account only for 0.7% of the polar lipids. The long-chain bases composition determined by thin-layer and gas chromatography shows a preponderance of trihydroxy bases and a small amount of dihydroxy bases. The striking finding was the high content of 19-phytosphingosine (90.8% of total long-chain bases). Fatty acid (FA) composition of polar lipids was characterized by the relatively high concentration of unsaturated fatty acids (66.4% of total FA) and by the predominance of fatty acids with 16 carbon atoms (85.0% of total FA).

Lipid analysis of the plasma membrane and mitochondria of brewer’s yeast

The plasma membrane and mitochondria of bottom fermenting brewer’s yeast obtained as a by-product of industrial beer production were isolated and the lipid fraction was analyzed. The phospholipid content accounted for 78 mg/g protein in the plasma membrane and 59 mg/g protein in the mitochondria. Major phospholipids in both preparations were phosphatidylinositol, phosphatidylcholine and phosphatidyl-ethanolamine but their proportions differed significantly. In the plasma membrane phosphatidy linositol, and in the mitochondria phosphatidylcholine were present in the highest concentration (37 and 30 %, respectively). The main classes of neutral lipids (triacylglycerols, ergosterol, squalene and steryl esters) were twice more abundant in the plasma membrane than in the mitochondria (61 and 33 mg/g protein, respectively). A characteristic of the neutral lipid composition of both organelles was the low content of ergosterol (12 and 7 mg/g protein, respectively) and a high content of squalene (25 and 22 mg/g protein). The main feature of the fatty acid composition of both organelles was the preponderance of saturated fatty acids (78 and 79 %, respectively), among which palmitic acid was the principal one. The most expressed characteristics of lipid fractions of the analyzed plasma membranes and mitochondria, high concentration of squalene and preponderance of saturated fatty acids are the consequences of anaerobic growth conditions. The lack of oxygen had possibly the strongest effect on the lipid composition of the plasma membranes and mitochondria of bottom fermenting brewer’s yeast.

Effect of indomethacin on motor activity and spinal cord free fatty acid content after experimental spinal cord injury in rabbits.

Study design:Determination of functional and biochemical parameters as well as the effect of specific therapies on these parameters, in the experimental model of neurotrauma in rabbits.Objective:To assess the effect of indomethacin (0.1–3.0 mg/kg for 9 days), a potent inhibitor of endogenous prostaglandin synthesis, on the motor activity and on the spinal cord tissue concentration of free palmitic, stearic, oleic, arachidonic and docosahexaenoic acids in an experimental model of a spinal cord injury in rabbits.Setting:Faculty of Medicine, University of Rijeka, Croatia.Methods:The animals were randomly divided into nine experimental groups, four sham and/or vehicle-treated and five indomethacin-treated (including one sham-operated and four injured groups). Laminectomy was followed by contusion of the spinal cord, using a modification of the technique of Albin. Motor activity was controlled daily during the course of the next nine postoperation days and scored using Tarlovs system. Spinal cord samples from the impact injury site were taken and frozen in liquid nitrogen. Total lipids were isolated and purified by a modification of the method of Folch. Free fatty acids (FFAs) were separated from the total lipid extract by preparative thin-layer chromatography, converted to the corresponding methyl esters and identified using gas chromatography, using nonadecanoic acid as the internal standard.Results:The concentrations of all analysed free fatty acids were increased in the spinal cord after neurotrauma, in comparison to control tissues. Treatment of injured rabbits with indomethacin resulted in a significant decrease in spinal cord FFAs and exerted a positive effect on neurotrauma-induced motor impairment.Conclusion:These results indicate a mechanism whereby indomethacin protects rabbits from the sequellae of neuronal damage caused by trauma, and suggests that it may be beneficial in the therapy of neurotrauma.Sponsorship:This work was supported by the Croatian Ministry of Science and Technology (project 062019).

Electron spin resonance measurement of radical scavenging activity of Aronia melanocarpa fruit juice.

Background: The fruits of Aronia melanocarpa (Michx.) Elliot contain large amounts of phenolic substances, mainly procyanidins, anthocyanins and other flavonoids, and phenolic acids. The ability of phenolic substances to act as antioxidants has been well established. Objective: In this study, we investigated the radical scavenging activity of A. melanocarpa fruit juice (AMFJ). Materials and Methods: The method used was electron spin resonance (ESR) spectroscopy. The galvinoxyl free radical was used as a scavenging object. AMFJ was added to the galvinoxyl free radical solution. The measure of the radical scavenging activity was the decrease of signal intensity. Results: AMFJ showed a potent antiradical activity causing a strong and rapid decrease of signal intensity as a function of time and juice concentration. This effect of AMFJ was probably due to the activity of its phenolic constituents. Conclusion: The ESR measurements in this study showed a pronounced radical scavenging effect of AMFJ, an important mechanism of its antioxidant activity.

The influence of fermentation conditions and recycling on the phospholipid and fatty acid composition of the brewer’s yeast plasma membranes

Phospholipid (PL) and fatty acid (FA) compositions of the plasma membrane (PM), as well as the FA composition of the PM phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn) in the pure culture (zero generation) and the first three recycled generations of the bottom-fermenting brewer’s yeast, have been determined. The PL composition differed markedly among the generations; in the zero generation, phosphatidylinositol (PtdIns) was the main PL, accounting for 27% of total PLs, followed by phosphatidic acid and PtdCho. In all recycled generations, the main PL was PtdCho with a marked increase in the first generation compared with the zero (32% and 20%, respectively), followed by PtdIns in the first and second generations. In the FA composition of the PM, 22 FAs were identified, ranging from C10 to C26. The compositions of the PM FAs, as well as those of PtdCho and PtdEtn, were characterised by a high preponderance of C16 acids. Saturated FAs prevailed in the zero generation, whilst unsaturated prevailed in the first and second generation. Although the profiles of FAs in PtdCho and PtdEtn were similar, some marked differences were observed, pointing out to their specific functions in the regulation of membrane properties.

Effect of Environmental Stress Factors and Recycling on the Lipid Composition of Brewer’s Yeast Mitochondria

Cilj istraživanja bio je odrediti promjene u sadržaju i sastavu lipida mitohondrija pivskog kvasca do kojih dolazi za vrijeme vrenja i recikliranja