Main Lipid Classes Research Articles

Lipidomics reveals skin surface lipid abnormity in acne in young men.

Acne is a complex and multifactorial skin disorder. Alterations in skin surface lipid (SSL) are believed to be an important factor in the pathogenesis of acne and SSL plays a key role in the initiation of acne lesions. To analyse the lipidome profiles of SSL in patients with acne and in healthy controls in order to understand SSL abnormity in acne in young men. Ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) and multivariate data analysis were used to investigate the SSL variations in main lipid classes, subclasses and individual species. Results showed that there were significant differences in the lipidome between the two groups. Significantly increased levels of three main classes of glycerophospholipids, fatty acyls and sterol lipids and significantly decreased levels of two main classes of prenol lipids and saccharolipids were observed in patients with acne. Subsequent analysis showed that there were 18 subclasses, which varied significantly and shared the same changing trends of the main classes to which they belonged. Multivariate data analysis indicated that 36 individual species were mostly responsible for this discrimination and the majority of differentiating lipid species were phosphatidylserines. Furthermore, it was observed that the chain length of ceramides were reduced and unsaturated free fatty acids were increased in patients with acne. SSL sampled from young male patients with acne had significantly higher levels of phosphatidylserines. Additionally, the reduction in the chain length of ceramides and the increase in unsaturated free fatty acids contributed to an altered lipid organization and decreased skin barrier function in acne.

Egg oxidation status, antioxidant enzyme activities, lipid classes, fatty acid composition profile and embryo survival rates during in vitro oocyte ageing in tenchTinca tinca(Linnaeus, 1758)

The effect of in vitro storage of oocytes on embryos survival rate, egg oxidation status, antioxidant enzyme activities, lipid classes and fatty acid composition profile was investigated in common tench Tinca tinca. In order to identify the role of oxidative stress in the progress of oocyte ageing the levels of thiobarbituric acid reactive substances (TBARS) and carbonyls as indicators of lipid and protein oxidation were measured and the activity of antioxidant enzymes were examined. Stripped ova from six females were stored in cell culture plates at 20°C for up to 10 hr post-stripping (HPS). The stored ova were fertilized and the embryo survival rates were assessed. The results indicated that tench eggs could be successfully stored in vitro for 4 hr after stripping at 20°C. Superoxide dismutase enzyme activity increased at 6 HPS, whereas glutathione peroxidase and glutathione reductase activities decreased in oocytes during in vitro storage (p < .05) at 4 and 8 HPSs, respectively. The level of malondialdehyde did not show any significant changes during the progress of oocyte ageing. Carbonyls increased up to 2 HPS and thereafter decreased significantly. However, ova ageing did not affect the main lipid class composition and the fatty acid composition of the eggs. Lower quality eggs exhibited lower levels of cholesterol but higher levels of triacylglycerol.

"Lipid raft aging" in the human frontal cortex during nonpathological aging: gender influences and potential implicationsin Alzheimer's disease.

Lipid rafts are highly dynamic membrane domains featured by distinctive biochemical composition and physicochemical properties compared with the surrounding plasma membrane. These microstructures are associated not only with cellular signaling and communication in normal nerve cells but also with pathological processing of amyloid precursor protein in Alzheimer's disease. Using lipid rafts isolated from human frontal cortex in nondemented subjects aging 24 to 85years, we demonstrate here that lipid structure of lipid rafts undergo significant alterations of specific lipid classes and phospholipid-bound fatty acids as brain cortex correlating with aging. Main changes affect levels of plasmalogens, polyunsaturated fatty acids (especially docosahexaenoic acid and arachidonic acid), total polar lipids (mainly phosphatidylinositol, sphingomyelin, sulfatides, and cerebrosides), and total neutral lipids (particularly cholesterol and sterol esters). Besides, relevant relationships between main fatty acids and/or lipid classes were altered in an age-related manner. This "lipid raft aging" exhibits clear gender differences and appear to be more pronounced in women than in men, especially in older (postmenopausal) women. The outcomes led us to conclude that human cortical lipid rafts are modified by aging in a gender-dependent fashion. Given the central role of bilayer lipid matrix in lipid rafts functionality and neuronal signaling, we hypothesize that these findings might underlie the higher prevalence of cognitive decline evolving toward Alzheimer's disease in postmenopausal women.

Cutis laxa, exocrine pancreatic insufficiency and altered cellular metabolomics as additional symptoms in a new patient with ATP6AP1-CDG

Congenital disorders of glycosylation (CDG) are genetic defects in the glycoconjugate biosynthesis. >100 types of CDG are known, most of them cause multi-organ diseases. Here we describe a boy whose leading symptoms comprise cutis laxa, pancreatic insufficiency and hepatosplenomegaly. Whole exome sequencing identified the novel hemizygous mutation c.542T>G (p.L181R) in the X-linked ATP6AP1, an accessory protein of the mammalian vacuolar H+-ATPase, which led to a general N-glycosylation deficiency. Studies of serum N-glycans revealed reduction of complex sialylated and appearance of truncated diantennary structures. Proliferation of the patient's fibroblasts was significantly reduced and doubling time prolonged. Additionally, there were alterations in the fibroblasts' amino acid levels and the acylcarnitine composition. Especially, short-chain species were reduced, whereas several medium- to long-chain acylcarnitines (C14-OH to C18) were elevated. Investigation of the main lipid classes revealed that total cholesterol was significantly enriched in the patient's fibroblasts at the expense of phophatidylcholine and phosphatidylethanolamine. Within the minor lipid species, hexosylceramide was reduced, while its immediate precursor ceramide was increased. Since catalase activity and ACOX3 expression in peroxisomes were reduced, we assume an ATP6AP1-dependent impact on the β-oxidation of fatty acids. These results help to understand the complex clinical characteristics of this new patient.

Spatial Relationship and Functional Relevance of Three Lipid Domain Populations at the Erythrocyte Surface

Background/Aims: Red blood cells (RBC) have been shown to exhibit stable submicrometric lipid domains enriched in cholesterol (chol), sphingomyelin (SM), phosphatidylcholine (PC) or ganglioside GM1, which represent the four main lipid classes of their outer plasma membrane leaflet. However, whether those lipid domains co-exist at the RBC surface or are spatially related and whether and how they are subjected to reorganization upon RBC deformation are not known. Methods: Using fluorescence and/or confocal microscopy and well-validated probes, we compared these four lipid-enriched domains for their abundance, curvature association, lipid order, temperature dependence, spatial dissociation and sensitivity to RBC mechanical stimulation. Results: Our data suggest that three populations of lipid domains with decreasing abundance coexist at the RBC surface: (i) chol-enriched ones, associated with RBC high curvature areas; (ii) GM1/PC/chol-enriched ones, present in low curvature areas; and (iii) SM/PC/chol-enriched ones, also found in low curvature areas. Whereas chol-enriched domains gather in increased curvature areas upon RBC deformation, low curvature-associated lipid domains increase in abundance either upon calcium influx during RBC deformation (GM1/PC/chol-enriched domains) or upon secondary calcium efflux during RBC shape restoration (SM/PC/chol-enriched domains). Hence, abrogation of these two domain populations is accompanied by a strong impairment of the intracellular calcium balance. Conclusion: Lipid domains could contribute to calcium influx and efflux by controlling the membrane distribution and/or the activity of the mechano-activated ion channel Piezo1 and the calcium pump PMCA. Whether this results from lipid domain biophysical properties, the strength of their anchorage to the underlying cytoskeleton and/or their correspondence with inner plasma membrane leaflet lipids remains to be demonstrated.

Investigation of trophic ecology in Newfoundland cold-water deep-sea corals using lipid class and fatty acid analyses

The trophic behavior of some deep-sea Newfoundland cold-water corals was explored using fatty acid (FA) and lipid profiles. No significant effect of geographic location and/or depth was identified in lipid or FA composition. However, differences were detected between and within taxon groups in hexa- or octocoral subclasses. Phospholipids constituted the main lipid class in all groups except black-thorny corals which had less structural lipids likely due to their morphology (stiff axes) and slower growth rates. Within each subclass, major differences in the identity of dominant FAs were detected at the order level, whereas differences between species and taxon groups of the same order were mainly driven by a variation in proportions of the dominant FA. Soft corals and gorgonians (Order Alcyonacea) were close in composition and are likely relying on phytodetritus resulting from algae, macrophytes and/or foraminifera, while sea pens (Order Pennatulacea) seem to consume more diatoms and/or herbivorous zooplankton with the exception of Pennatula sp. In the hexacoral subclass, black-thorny corals (Stauropathes arctica) differed significantly from the stony-cup corals (Flabellum alabastrum); S. arctica was seemingly more carnivorous (zooplankton markers) than F. alabastrum, which appears omnivorous (phyto- and zooplankton markers). Our results suggest that deep-sea corals are not as opportunistic as expected but have some selective feeding associated with taxonomy.

A Comparison of the Composition of Wax Ester Molecular Species of Different Coral Groups (Subclasses Hexacorallia and Octocorallia)

Wax esters, which are esters of fatty alcohols and fatty acids (FAs), are one of the main classes of reserve lipids in all coral species. The chemical structures and the content of wax ester molecular species were determined for the first time in nine coral species from three taxonomic groups: symbiotic reef-building corals, (Hexacorallia subclasses), symbiotic soft coral alcyonarians, and asymbiotic soft coral gorgonians (Octocorallia subclasses) collected in the South China Sea (Vietnam). Our comparison of these groups showed that the absence of symbiotic microalgae (zooxanthellae) and the exoskeleton affects the profile of molecular species of wax esters considerably. The main components of wax esters of all corals were cetyl palmitate (16:0-16:0) and other saturated wax esters containing 30, 34, and 36 carbon atoms. The content of unsaturated molecular species 6:0–16:1, 16:0–18:1, and 16:0–20:1 in wax esters of symbiotic soft corals (alcyonarians) was greater than that in wax esters of reef-building corals. In contrast to symbiotic coral species, wax esters of asymbiotic soft corals, namely azooxanthellate gorgonians, contained a considerable amount of long-chain molecular species (C37-C41) with an odd number of carbon atoms. The presence of such molecular species indicates that asymbiotic gorgonians may use bacterial FAs in biosynthesis of their own wax esters. This observation confirms our hypothesis that bacterial community is important for maintaining the energy balance of azooxanthellate corals.

Serum lipid feature and potential biomarkers of lethal ventricular tachyarrhythmia (LVTA) induced by myocardial ion channel diseases: a rat model study.

To determine the cause of death in myocardial ion channel diseases (MICD)-induced sudden cardiac death (SCD) cases is a difficulty in forensic identification practices. The majority of MICD-induced SCD cases would experience lethal ventricular tachyarrhythmia (LVTA) before deaths; thus, confirming the occurrence of LVTA in bodies can offer a key evidence to identify these cases. Several lipids in the myocardia were found disturbed after LVTA; yet, whether serum lipidome would be disrupted by LVTA is not clear. Therefore, we aimed to screen lipid feature and related diagnostic markers of LVTA in serum here. An aconitine-induced LVTA-SCD rat model was produced. Blood samples before LVTA and immediately after LVTA were retrieved and related serum specimens were used for ultra-performance liquid chromatography-mass spectrometry (UPLC-MS)-based lipidomics analyses. On the basis of the defined differential lipids, a lipid-related metabolic pathway network was constructed and potential biomarkers were screened. Twelve aconitine-induced LVTA rats were produced. Totally, 188 lipids in serum were disrupted during the LVTA-SCD process, which belong to 11 lipid classes. Most of the differential lipids were correlated, suggesting that they were interacted and that the changes were holistic during LVTA process. Ten lipid pathways were activated during LVTA process; the main lipid classes involved in these pathways were ceramide, sphingomyelin, phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine. Phosphatidylcholine O-40:4, sphingomyelin d46:5, and phosphatidylethanolamine 40:4 were tested as potential diagnostic markers of LVTA-SCD event in serum. The current results indicate a substantial change in serum lipidome after LVTA-SCD; lipidomics holds promise to identify MICD-induced SCDs in forensic practices.

Fatty acid profiles of the main lipid classes of green seaweeds from fish pond aquaculture.

The lipid composition of five species of green seaweeds (Chaetomorpha linum, Rhizoclonium riparium, Ulva intestinalis, Ulva lactuca, and Ulva prolifera) grown in fish pond aquaculture systems was studied. In particular, the overall fatty acid (FA) profile and the FA profile of each main lipid class found in these seaweed species were thoroughly analyzed. It was found that every seaweed had a specific FA profile, whose specificities were rendered more obvious with the study of the FA profile per lipid class. However, between U. lactuca and U. intestinalis, there were only minor differences. Nonetheless, it was possible to identify significant differences between the palmitic acid content in the phospholipid (PL) and glycolipid (GL) classes of each seaweed. A clear distinction between the FA profiles of R. riparium and C. linum, which belong to the Cladophorales order, and those of Ulva genus, Ulvales order, was also determined. Moreover, there were also differences among lipid classes, yielding large contrasts between PLs + GLs and triacylglycerols (TAGs) as well as between monoacylglycerols (MAGs) and free fatty acids (FFAs). This study also found evidence supporting the location of particular FAs in specific TAG positions. FA profiles have the potential to be used as a chemotaxonomic tool in green seaweeds, providing a simple method to check authenticity of seaweed used as food.

Influence of the Cation Adducts in the Analysis of Matrix-Assisted Laser Desorption Ionization Imaging Mass Spectrometry Data from Injury Models of Rat Spinal Cord.

Imaging mass spectrometry (IMS) is quickly becoming a technique of reference to visualize the lipid distribution in tissue sections. Still, many questions remain open, and data analysis has to be optimized to avoid interpretation pitfalls. Here we analyze how the variation on the [Na+]/[K+] relative abundance affects the detection of lipids between sections of spinal cord of (uninjured) control rats and of models of spinal cord demyelination and traumatic contusion injury. The [M + Na]+/[M + K]+ adducts ratio remained approximately constant along transversal and longitudinal sections of spinal cord from control animals, but it strongly changed depending on the type of lesion. A substantial increase in the abundance of [M + Na]+ adducts was observed in samples from spinal cord with demyelination, while the intensity of the [M + K]+ adducts was stronger in those sections from mechanically injured spinal cords. Such changes masked the modifications in the lipid profile due to the injury and only after summing the signal intensity of all adducts and corresponding monoprotonated molecular ions of each detected lipid in a single variable, it was possible to unveil the real changes in the lipid profile due to the lesion. Such lipids included glycerophospholipids (both diacyl and aryl-acyl), sphingolipids, and nonpolar lipids (diacyl and triacylglycerols), which are the main lipid classes detected in positive-ion mode. Furthermore, the results demonstrate the sensitivity of the technique toward modification in tissue homeostasis and that the [M + Na]+/[M + K]+ ratio may be used to detect alterations in such homeostasis.

Comprehensive identification of age-related lipidome changes in rat amygdala during normal aging.

Brain lipids are integral components of brain structure and function. However, only recent advancements of chromatographic techniques together with mass spectrometry allow comprehensive identification of lipid species in complex brain tissue. Lipid composition varies between the individual areas and the majority of previous reports was focusing on individual lipids rather than a lipidome. Herein, a mass spectrometry-based approach was used to evaluate age-related changes in the lipidome of the rat amygdala obtained from young (3 months) and old (20 months) males of the Sprague-Dawley rat strain. A total number of 70 lipid species with significantly changed levels between the two animal groups were identified spanning four main lipid classes, i.e. glycerolipids, glycerophospholipids, sphingolipids and sterol lipids. These included phospholipids with pleiotropic brain function, such as derivatives of phosphatidylcholine, phosphatidylserine, and phosphatidylethanolamine. The analysis also revealed significant level changes of phosphatidic acid, diacylglycerol, sphingomyelin and ceramide that directly represent lipid signaling and affect amygdala neuronal activity. The amygdala is a crucial brain region for cognitive functions and former studies on rats and humans showed that this region changes its activity during normal aging. As the information on amygdala lipidome is very limited the results obtained in the present study represent a significant novelty and may contribute to further studies on the role of lipid molecules in age-associated changes of amygdala function.

Bioactive fatty acids in mantis shrimp, crab and caramote prawn: Their content and distribution among the main lipid classes

The profile and distribution of fatty acids in neutral lipids, phosphatidylethanolamine and phosphatidylcholine of appreciated crustaceans species caught in the Adriatic Sea during the autumn months, namely caramote prawn (Penaeus kerathurus), mantis shrimp (Squilla mantis) and crab (Liocarcinus vernalis), were investigated. The crab’s total fatty acid profile significantly differed from that of caramote prawn and mantis shrimp. Crab was the most valuable dietary source of omega-3 polyunsaturated fatty acids (n–3 PUFA), with approximately 2-fold higher eicosapentaenoic acid content (131.6±31.6mg/100g of edible part) than caramote prawn and mantis shrimp. The caramote prawn presented the highest furan fatty acids (F-acids) level (2.5±0.5mg/100g). All crustaceans preferentially accumulated the n–3 PUFA in phosphatidylethanolamine fraction. The F-acid distribution among the lipid classes changed according to the crustacean species. Crab presented F-acids mainly in the neutral lipid whereas caramote prawn contained them predominantly in the phospholipids. On the contrary, F-acids were not detected in the phosphatidylcholine of mantis shrimp. These differences in the distribution suggest different nutritional and health properties given by the consumption of the crustaceans investigated. Moreover, the F-acid profile of the different lipid classes could be used to discriminate these crustaceans.

A Simple Method for Measuring Carbon-13 Fatty Acid Enrichment in the Major Lipid Classes of Microalgae Using GC-MS.

A simple method for tracing carbon fixation and lipid synthesis in microalgae was developed using a combination of solid-phase extraction (SPE) and negative ion chemical ionisation gas chromatography mass spectrometry (NCI-GC-MS). NCI-GC-MS is an extremely sensitive technique that can produce an unfragmented molecular ion making this technique particularly useful for stable isotope enrichment studies. Derivatisation of fatty acids using pentafluorobenzyl bromide (PFBBr) allows the coupling of the high separation efficiency of GC and the measurement of unfragmented molecular ions for each of the fatty acids by single quadrupole MS. The key is that isotope spectra can be measured without interference from co-eluting fatty acids or other molecules. Pre-fractionation of lipid extracts by SPE allows the measurement of 13C isotope incorporation into the three main lipid classes (phospholipids, glycolipids, neutral lipids) in microalgae thus allowing the study of complex lipid biochemistry using relatively straightforward analytical technology. The high selectivity of GC is necessary as it allows the collection of mass spectra for individual fatty acids, including cis/trans isomers, of the PFB-derivatised fatty acids. The combination of solid-phase extraction and GC-MS enables the accurate determination of 13C incorporation into each lipid pool. Three solvent extraction protocols that are commonly used in lipidomics were also evaluated and are described here with regard to extraction efficiencies for lipid analysis in microalgae.

Tailored Extraction Procedure Is Required To Ensure Recovery of the Main Lipid Classes in Whole Blood When Profiling the Lipidome of Dried Blood Spots

The use of dried blood spots has increased in research and clinical settings recently, particularly in field studies and screening, but comprehensive acyl-specific lipidomic profiling of dried blood spots has yet to be examined. An untargeted ultrahigh-performance liquid chromatography-tandem mass spectrometry method was adapted for the analysis of lipid extracts from human whole blood samples and dried blood spots collected on chromatography paper. Lipid recoveries were examined after different durations of exposure to extraction solvents (chloroform/methanol), physical disruption (homogenization or sonication) of the paper containing the dried blood spots, and acidification of extraction solvents. We demonstrated that comprehensive untargeted profiles can be obtained from dried blood spot samples that are comparable with whole blood for several species of lipids including phosphatidylcholine, lyso-phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, triacylglycerol, and cholesteryl ester. However, homogenization of the dried blood spots, followed by a 24 h exposure to solvents, and extraction with an acidic buffer (0.2 M NaHPO4 + 0.1 M hydrochloric acid) was required. Dried blood spots can be used for comprehensive, untargeted lipidomics of the most abundant lipid species in whole blood, but additional sample processing steps are required.

Free fatty acids chain length distribution affects the permeability of skin lipid model membranes

The lipid matrix in the stratum corneum (SC) plays an important role in the barrier function of the skin. The main lipid classes in this lipid matrix are ceramides (CERs), cholesterol (CHOL) and free fatty acids (FFAs). The aim of this study was to determine whether a variation in CER subclass composition and chain length distribution of FFAs affect the permeability of this matrix. To examine this, we make use of lipid model membranes, referred to as stratum corneum substitute (SCS). We prepared SCS containing i) single CER subclass with either a single FFA or a mixture of FFAs and CHOL, or ii) a mixture of various CER subclasses with either a single FFA or a mixture of FFAs and CHOL. In vitro permeation studies were performed using ethyl-p-aminobenzoic acid (E-PABA) as a model drug. The flux of E-PABA across the SCS containing the mixture of FFAs was higher than that across the SCS containing a single FA with a chain length of 24 C atoms (FA C24), while the E-PABA flux was not effected by the CER composition. To select the underlying factors for the changes in permeability, the SCSs were examined by Fourier transform infrared spectroscopy (FTIR) and Small angle X-ray scattering (SAXS). All lipid models demonstrated a similar phase behavior. However, when focusing on the conformational ordering of the individual FFA chains, the shorter chain FFA (with a chain length of 16, 18 or 20 C atoms forming only 11m/m% of the total FFA level) had a higher conformational disordering, while the conformational ordering of the chains of the CER and FA C24 and FA C22 hardly did not change irrespective of the composition of the SCS. In conclusion, the conformational mobility of the short chain FFAs present only at low levels in the model SC lipid membranes has a great impact on the permeability of E-PABA.

Profiling of complex lipids in marine microalgae by UHPLC/tandem mass spectrometry

Microalgal lipids are of great interest for their potential as food and feed ingredients, nutraceutical and cosmetic components, and as source of energy. Glycerol-based lipids can constitute up to 50% or more of the biomass of microalgae. How synthesis of these products takes place is still poorly explored, although remarkable differences with plants and among microalgal species have already emerged. These differences attain to both lipid class and fatty acyl composition, which could be modulated by specific growth conditions. Here we present a new method based on UHPLC coupled to high resolution tandem mass spectrometry for targeted analysis of the main lipid classes, i.e., glycolipids, phospholipids and triacylglycerols, applied to five marine microalgae exhibiting a great diversity in lipid composition. The LC/MS/MS approach is integrated with a recently proposed MTBE-based protocol for lipid extraction and the entire workflow is of general application to lipid profiling of cell extracts from different sources.

Stratum Corneum Lipids: Their Role for the Skin Barrier Function in Healthy Subjects and Atopic Dermatitis Patients.

Human skin acts as a primary barrier between the body and its environment. Crucial for this skin barrier function is the lipid matrix in the outermost layer of the skin, the stratum corneum (SC). Two of its functions are (1) to prevent excessive water loss through the epidermis and (2) to avoid that compounds from the environment permeate into the viable epidermal and dermal layers and thereby provoke an immune response. The composition of the SC lipid matrix is dominated by three lipid classes: cholesterol, free fatty acids and ceramides. These lipids adopt a highly ordered, 3-dimensional structure of stacked densely packed lipid layers (lipid lamellae): the lateral and lamellar lipid organization. The way in which these lipids are ordered depends on the composition of the lipids. One very common skin disease in which the SC lipid barrier is affected is atopic dermatitis (AD). This review addresses the SC lipid composition and organization in healthy skin, and elaborates on how these parameters are changed in lesional and nonlesional skin of AD patients. Concerning the lipid composition, the changes in the three main lipid classes and the importance of the carbon chain lengths of the lipids are discussed. In addition, this review addresses how these changes in lipid composition induce changes in lipid organization and subsequently correlate with an impaired skin barrier function in both lesional and nonlesional skin of these patients. Furthermore, the effect of filaggrin and mutations in the filaggrin gene on the SC lipid composition is critically discussed. Also, the breakdown products of filaggrin, the natural moisturizing factor molecules and its relation to SC-pH is described. Finally, the paper discusses some major changes in epidermal lipid biosynthesis in patients with AD and other related skin diseases, and how inflammation has a deteriorating effect on the SC lipids and SC biosynthesis. The review ends with perspectives on future studies in relation to other skin diseases.

Adaptation of Skyline for Targeted Lipidomics.

In response to the urgent need for analysis software that is capable of handling data from targeted high-throughput lipidomics experiments, we here present a systematic workflow for the straightforward method design and analysis of selected reaction monitoring data in lipidomics based on lipid building blocks. Skyline is a powerful software primarily designed for proteomics applications where it is widely used. We adapted this tool to a "Plug and Play" system for lipid research. This extension offers the unique capability to assemble targeted mass spectrometry methods for complex lipids easily by making use of building blocks. With simple yet tailored modifications, targeted methods to analyze main lipid classes such as glycerophospholipids, sphingolipids, glycerolipids, cholesteryl-esters, and cholesterol can be quickly introduced into Skyline for easy application by end users without distinct bioinformatics skills. To illustrate the benefits of our novel strategy, we used Skyline to quantify sphingolipids in mesenchymal stem cells. We demonstrate a simple method building procedure for sphingolipids screening, collision energy optimization, and absolute quantification of sphingolipids. In total, 72 sphingolipids were identified and absolutely quantified at the fatty acid scan species level by utilizing Skyline for data interpretation and visualization.

Alleviation of cadmium stress in Solanum lycopersicum L. by arbuscular mycorrhizal fungi via induction of acquired systemic tolerance

Experiments were conducted to evaluate cadmium (Cd) stress-induced changes in growth, antioxidants and lipid composition of Solanum lycopersicum with and without arbuscular mycorrhizal fungi (AMF). Cadmium stress (50μM) caused significant changes in the growth and physio-biochemical attributes studied. AMF mitigated the deleterious impact of Cd on the parameters studied. Cadmium stress increased malonaldehyde and hydrogen peroxide production but AMF reduced these parameters by mitigating oxidative stress. The activity of antioxidant enzymes enhanced under Cd treatment and AMF inoculation further enhanced their activity, thus strengthening the plant’s defense system. Proline and phenol content increased in Cd-treated as well as AMF-inoculated plants providing efficient protection against Cd stress. Cadmium treatment resulted in great alterations in the main lipid classes leading to a marked change in their composition. Cadmium stress caused a significant reduction in polyunsaturated fatty acids resulting in enhanced membrane leakage. The present study supports the use of AMF as a biological means to ameliorate Cd stress-induced changes in tomato.

Lipid characterization of an arachidonic acid-rich oil producing fungus Mortierella alpina

Mortierella alpina has been considered as the most effective producer of arachidonic acid (ARA)-rich oil. It was found that several methods could improve the percentage of ARA in total lipids successfully, as they activated the desaturation system on the endoplasmic reticulum. Additionally, in M. alpina the ARA exists in several forms, such as triacylglycerol (TAG), and diacylglycerol (DAG). These forms are caused by different acyltransferases and they determine the nutrient value of the microbial oil. However, few works revealed detailed fatty acid distribution among lipid classes, which to some extent impeded the accurate regulation in ARA accumulation. Herein, this paper gives information on the accumulation process of main lipid classes and the changes of fatty acid composition in these lipids during ARA accumulation period in M. alpina. The result demonstrates that TAG was the dominant component of the total lipids, and it is the main form for ARA storage. The ARA enrichment stage occurred during 168–192h when the amount of total lipids maintained steady. Further analysis indicated that the newly formed ARA-TAG might come from the incorporation and modification of saturated and monounsaturated fatty acids in other lipid classes. This work could be helpful for further optimization of ARA-rich TAG production.