Ceramide Aminoethylphosphonate Research Articles

Metabolic responses of sea anemone and jellyfish to temperature and UV bleaching: Insights into stress adaptation using LCMS-based metabolomics, molecular networking and chemometrics

IntroductionClimate change poses various threats to marine life, particularly in shallow tropical waters. Objective: The impact of increased temperature and ultraviolet (UV) exposure on two photosymbiotic cnidarians, a common bubble-tip anemone and an upside-down jellyfish, was investigated. MethodsTo illustrate the response of aquatic organisms, the metabolomes of unstressed Entacmaea quadricolor and Cassiopea andromeda were compared for detailed metabolite profiling. UHPLC-MS coupled with chemometrics and GNPS molecular networking was employed for sample classification and identification of markers unique to stress responses in each organism. ResultsSeveral compounds with bioactive functions, including peptides and terpenoids, were reported for the first time in both organisms, viz. cyclic tetraglutamate, campestriene, and ceramide aminoethyl phosphonate (CEAP d18:2/16:0). Both anemone and jellyfish were subjected to either elevated UV-B light intensity up to 6.6 KJ m−2 or increased temperatures (28 °C, 30 °C, 32 °C, and 34 °C) over 4 days. Phospholipids, steroids, and ceramides emerged as chief markers of both types of stress, as revealed by the multivariate data analysis. Lysophosphatidylcholine (LPC 16:0), LPC (18:0/0:0), and echinoclasterol sulfate appeared as markers in both UV and thermal stress models of the anemone, whereas methyl/propyl cholestane-hexa-ol were discriminatory in the UV stress model only. In the case of jellyfish, nonpolar glycosyl ceramide GlcCer (d14:1/28:6) served as a marker for UV stress, whereas polar peptides were elevated in the thermal stress model. Interestingly, both models of jellyfish share a phospholipid, lysophosphatidylethanolamine (LPE 20:4), as a distinctive marker for stress, reported to be associated indirectly with the activity of innate immune response within other photosymbiotic Cnidaria such as corals and appears to be a fundamental stress response in marine organisms. ConclusionThis study presents several bioinformatic tools for the first time in two cnidarian organisms to provide not only a broader coverage of their metabolome but also broader insights into cnidarian bleaching in response to different stressors, i.e., heat and UV light, by comparing their effects in anemone versus jellyfish.

Sexual dimorphism in the gonad lipidome of blue mussels (Mytilus sp.): New insights from a global lipidomics approach

Blue mussels (Mytilus sp.) are an economically important species for European aquaculture. Their importance as a food source is expected to increase in the coming net-zero society due to their low environmental footprint; however, their production is affected by anthropogenic stressors and climate change. During reproduction, lipids are key molecules for mussels as they are the main source of energy on which newly hatched embryos depend in the first days of their development. In this work, blue mussels of different origins are analysed, focusing on the differences in lipid composition between the ovary (BMO) and the testis (BMT). The lipidome of blue mussel gonads (BMG) is studied here by combining traditional lipid profiling methods, such as fatty acid and lipid class analysis, with untargeted liquid chromatography-mass spectrometry (LC-MS) lipidomics. The approach used here enabled the identification of 770 lipid molecules from 23 different lipid classes in BMG. BMT, which consists of billions of spermatocytes, had greater amounts of cell membrane and membrane lipid components such as FA18:0, C20 polyunsaturated fatty acids (PUFA), free sterols (ST), ceramide phosphoethanolamines (CerPE), ceramide aminoethylphosphonates (CAEP), cardiolipins (CL), glycerophosphocholines (PC), glycerophosphoethanolamines (PE) and glycerophosphoserines (PS). In BMO, saturated fatty acids (FA14:0 and FA16:0), monounsaturated fatty acids (MUFA) and other storage components such as C18-PUFA accumulated in triradylglycerolipids (TG) and alkyldiacylglycerols (neutral plasmalogens, TG O-), which, together with terpenes, wax esters and cholesterol esters, make up most of oocytes yolk reserves. BMO also had higher levels of ceramides (Cer) and generally alkyl/alkenyl glycerophospholipids (mainly plasmanyl/plasmenyl PC), suggesting a role for these lipids in vitellogenesis. Non-methylene interrupted dienoic fatty acids (NMID FA), typically found in plasmalogens, were the only membrane-forming PUFA predominantly detected in BMO. The results of this study are of great importance for clarifying the lipid composition of BMG and provide an important basis for future studies on the reproductive physiology of these organisms.

Ceramide Aminoethylphosphonate as a New Molecular Target for Pore-Forming Aegerolysin-Based Protein Complexes.

Ostreolysin A6 (OlyA6) is a 15 kDa protein produced by the oyster mushroom (Pleurotus ostreatus). It belongs to the aegerolysin family of proteins and binds with high affinity to the insect-specific membrane sphingolipid, ceramide phosphoethanolamine (CPE). In concert with its partnering protein with the membrane-attack-complex/perforin domain, pleurotolysin B (PlyB), OlyA6 can form bicomponent 13-meric transmembrane pores in artificial and biological membranes containing the aegerolysin lipid receptor, CPE. This pore formation is the main underlying molecular mechanism of potent and selective insecticidal activity of OlyA6/PlyB complexes against two economically important coleopteran plant pests: the western corn rootworm and the Colorado potato beetle. In contrast to insects, the main sphingolipid in cell membranes of marine invertebrates (i.e., molluscs and cnidarians) is ceramide aminoethylphosphonate (CAEP), a CPE analogue built on a phosphono rather than the usual phosphate group in its polar head. Our targeted lipidomic analyses of the immune cells (hemocytes) of the marine bivalve, the mussel Mytilus galloprovincialis, confirmed the presence of 29.0 mol% CAEP followed by 36.4 mol% of phosphatidylcholine and 34.6 mol% of phosphatidylethanolamine. Further experiments showed the potent binding of OlyA6 to artificial lipid vesicles supplemented with mussel CAEP, and strong lysis of these vesicles by the OlyA6/PlyB mixture. In Mytilus haemocytes, short term exposure (max. 1 h) to the OlyA6/PlyB mixture induced lysosomal membrane destabilization, decreased phagocytic activity, increased Annexin V binding and oxyradical production, and decreased levels of reduced glutathione, indicating rapid damage of endo-lysosomal and plasma membranes and oxidative stress. Our data suggest CAEP as a novel high-affinity receptor for OlyA6 and a target for cytolytic OlyA6/PlyB complexes.

Fatty acid, the lipid classes, phospholipid composition of the mussels \(\textit{Beguina semiorbiculata}\) from Nam Du and Phu Quoc islands, Kien Giang province, Vietnam

This study aims to analyze compositions of lipid classes, phospholipid subclasses and fatty acids in two mussels, Beguina semiorbiculata, harvested from Nam Du and Phu Quoc islands, Kien Giang province. The obtained results indicated that the total lipid contents of the B. semiorbiculata harvested in Nam Du and Phu Quoc islands were 0.48% and 0.63% of wet weight, respectively, and contained six classes: Hydrocarbon and wax (HW), triacylglycerol (TAG), free fatty acids (FFA), sterol (ST), polar lipid (PoL), and monoalkyl diacylglycerol (MADAG). Two main classes in the total lipid content of two studied mussels were triacylglycerol (TG) (38.22% and 41.27%) and polar lipid (PL) (27.02% and 30.46%). PL of both muselles consited of five types: Phosphatidylethalnolamine (PE), phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylinositol (PI) and ceramide aminoethylphosphonate (CAEP) in which phosphatidylethanolamine (PE) (34.34% and 37.08%) and phosphatidylcholine (PC) (26.32% and 26.54%) were dominated. The content of polyunsaturated fatty acids (34.41%) in the total lipid of B. semiorbiculata collected in Phu Quoc was higher than that (26.36%) in Nam Du. The content of n-3 and n-6 fatty acids (20:4n-6, 20:5n-3, 22:6n-3) was high in the composition of fatty acids of both mussels.

Lipid composition and molecular species of phospholipid in oyster Crassostrea lugubris (Sowerby, 1871) from Lang Co Beach, Hue Province, Vietnam.

Oysters are widely distributed worldwide, but are mainly concentrated in tropics and subtropics. Total lipid (TL), fatty acid (FA) composition of TL and polar lipid (PoL) fractions, phospholipid (PL) class, and molecular species composition in soft tissues of Crassostrea lugubris were investigated for the first time from Vietnam. Phosphatidylglycolic acid (PGA) is the new phospholipid class first identified in marine species in general and Crassostrea lugubris in particular. Main eight classes of PL were determined in PoL fraction: diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylinositol (PI), phosphatidylserine (PS), ceramide aminoethylphosphonate (CAEP), CAEP with hydroxylated FAs (CAEP‐OH), and lysophosphatidylcholine. PE and PC accounted for approximately 63% of total known PL. Polyunsaturated FAs accounted for more than 30% of TL. Ninety molecular species of glycerophospholipids, including PGA, PE, PC, PS, PI, DPG, and PG, and sphingophosphonolipids (CAEP) were identified in PoL. Alkenyl‐acyl forms of glycerophospholipids were predominated in the molecular species of PGA, PE, and PS. PGA 38:1 (p18:0/20:1), PE 40:6 (p18:0/22:6 and p18:1/22:5), PC 30:0 (14:0/16:0), PS 38:1 (p18:0/20:1), PI 40:5 (20:1/20:4), PG 32:0 (16:0/16:0), DPG 88:24 (22:6/22:6/22:6/22:6), and CAEP 34:2 (d18:2/16:0) were major molecular species.

Lipidome of the reef-building coral Acropora cerealis: Changes under thermal stress

Coral bleaching is caused by complete or partial loss of coral endosymbionts in response to increased sea surface temperature and solar radiation. A thermal stress leads to formation of reactive oxygen species resulting in a disturbance of coral cell membranes. Lipids are an essential component of cell membranes. The lipidome of the hard coral Acropora cerealis and its alteration under thermal stress were studied. The features of A. cerealis lipids were trace amounts of monoalkyldiacylglycerols, a high content of triacylglycerols with 18:3 and 22:6 fatty acids and а high content of ceramide aminoethylphosphonate. A short-term exposure of coral fragments at 33 °C caused significant changes in lipids. Among the storage lipids, the content of triacylglycerols decreased after 12-h exposure. Among the structural lipids, contents of ethanolamine-, choline-, and inositolglycerophospholipids decreased; the most pronounced changes were observed in the composition of phosphatidylethanolamine and phosphatidylinositol after 24-h exposure.

Dietary ceramide 2-aminoethylphosphonate, a marine sphingophosphonolipid, improves skin barrier function in hairless mice

Sphingolipids are one of the major components of cell membranes and are ubiquitous in eukaryotic organisms. Ceramide 2-aminoethylphosphonate (CAEP) of marine origin is a unique and abundant sphingophosphonolipid with a C-P bond. Although molluscs such as squids and bivalves, containing CAEP, are consumed globally, the dietary efficacy of CAEP is not understood. We investigated the efficacy of marine sphingophosphonolipids by studying the effect of dietary CAEP on the improvement of the skin barrier function in hairless mice fed a diet that induces severely dry-skin condition. The disrupted skin barrier functions such as an increase in the transepidermal water loss (TEWL), a decrease in the skin hydration index, and epidermal hyperplasia were restored by CEAP dietary supplementation. Correspondingly, dietary CAEP significantly increased the content of covalently bound ω-hydroxyceramide, and the expression of its biosynthesis-related genes in the skin. These effects of dietary CAEP mimic those of dietary plant glucosylceramide. The novel observations from this study show an enhancement in the skin barrier function by dietary CAEP and the effects could be contributed by the upregulation of covalently bound ω-hydroxyceramide synthesis in the skin.

Effect of experimental thermal stress on lipidomes of the soft coral Sinularia sp. and its symbiotic dinoflagellates

A complete or partial loss of symbiotic dinoflagellates (SD) by the corals in response to thermal stress has been described as coral bleaching. A stress damages the photosynthetic apparatus of SD and their thylakoid membranes, and symbiotic alga cells disappear via exocytosis and/or apoptosis resulting in a disturbance of host cell membranes. Lipids play an essential role in coral metabolism and constitute the basis of membranes. At present, studies of coral bleaching typically deal with long-term lipid indices, such as total lipids and fatty acids (FAs), while short-term dynamics of lipidome (full range of all lipid molecular species) has not been considered in the context of bleaching mechanism. To evaluate the lipidomic approach to characterizing coral bleaching, the soft coral Sinularia sp. was exposed to a short-term experimental thermal stress (33 °C). The dynamics of chlorophyll level, the composition of total FAs, the amounts of total lipids and major lipid classes (such as wax esters (WE), triacylglycerols (TAG), and monoalkyldiacylglycerols (MADAG), glycolipids, ethanolamine-, choline-, serine-, inositolglycerophospholipids (PE, PC, PS, PI), and ceramide aminoethylphosphonate (CAEP)) and the variations in the content of lipid molecular species were studied during a 36-h heat exposure. >160 molecular species were identified by tandem high-resolution mass spectrometry. Under the short-term stress, a considerable decline in the levels of chlorophylls, glycolipids, and FA markers of SD was detected, whereas the variations in the content of total lipids, total phospholipids, and major FAs were not significant. The heat exposure immediately disturbed the daily cycle of the composition of glycolipid molecular species. Among the storage lipids, the content of TAG and MADAG decreased, whereas the content of polyunsaturated WE molecular species increased under the stress. The following effects were recorded for the structural lipids: a depletion in the PE, PC, and PI amounts, a conversion of PE into their lyso and oxidized derivatives, an appearance of diacyl form of PE, and a disturbance of transfer of some polyunsaturated FAs from SD to the host. The content of PS was relatively stable. Probably, PE molecular species are a primary target of thermal stress in the Sinularia host. The most dramatical changes in the Sinularia lipidome were detected between 24 h and 36 h of the exposure. A lipidomic approach is important for studies of dynamics of the coral symbiotic association and a resistance of different coral taxa during short-term bleaching events.

Comparative lipid profile of four edible shellfishes by UPLC-Triple TOF-MS/MS

An ultra performance liquid chromatography-Triple time of flight mass spectrometry (UPLC-Triple TOF-MS/MS) method were established to characterize the lipid profiles in four shellfish species. More than 600 lipid molecular species belonging to 14 classes were detected. Phospholipids (PLs) were predominant in Chlamys farreri (54.9%) and glycerolipids (GLs) were dominant in Ostrea gigas (51.6%). PLs that contained polyunsaturated fatty acids (PUFAs) such as PC (16:0/20:5), PC (16:0/22:6) and PE (18:0/22:6) were the main molecular species. Especially, the percentage of sphingolipids (SLs) in four shellfishes is considerable (18.8–38.6%), the characterization of their special long-chain base (LCB) structure (mainly d19:3) and N-acyl group (mainly 16:0) was realized. Several SL subclasses with low abundance in four shellfish species, such as ceramide 2-aminoethylphosphonate (CAEP) and deoxy-ceramide (DeoxyCer), were also detected. These active lipids identified by this method have potential value in revealing the nutritional value of shellfishes and serving as biomarkers for distinguishing different shellfishes.

Lipidomic study of the influence of dietary fatty acids on structural lipids of cold-water nudibranch molluscs

Nudibranch molluscs occur in marine ecosystems worldwide and prey on numerous invertebrate species. During feeding, dietary fatty acids (FAs) unusual for nudibranchs are transferred to their lipids. Normal biomembrane functions require stable composition of structural polar lipids (PL), but the pathways of dietary FA utilization to PL in nudibranchs still remain unknown. A combination of chromatography and tandem high-resolution mass spectrometry was used to determine total lipid, PL, FA, and PL molecular species composition of two cold-water species of Dendronotus, which then were compared with those of Tritonia tetraquetra. The use of FA trophic markers showed that Dendronotus sp. and T. tetraquetra prey on different soft corals, while D. robustus may consumes hydrocorals and bryozoans. Nudibranch FA profiles were strongly modified by dietary FAs but their PL profilers were similar. Dietary FAs are not included in ceramide aminoethylphosphonate and inositol glycerophospholipids, but directed to ethanolamine, choline, and serine glycerophospholipids and, in some cases, form isobaric molecular species with different FA chain lengths. For such isobaric species, nudibranchs reduce the length of alkyl groups when very-long-chain FAs are obtained with diet. This molecular mechanism may explain the adaptation of nudibranch membrane structure to dietary input of unusual FAs.

Identification of ceramide 2-aminoethylphosphonate molecular species from different aquatic products by NPLC/Q-Exactive-MS

Ceramide 2-aminoethylphosphonate (CAEP) is a type of phosphonosphingolipids with potential trophic activity. In this work, complicated CAEP species from different aquatic products were comprehensively identified and semi-quantified by utilizing normal phase liquid chromatography/Q-Exactive mass spectrometry (NPLC/Q-Exactive-MS). We elucidated the fragment schemes of CAEP molecules and found the presence of methylated CAEP (Me-CAEP) species. Remarkably, quantitative results revealed that Loligo chinensis had the highest CAEP content of 4.9 ± 0.4 mg/g dry weight and the most complex molecular species composition, whereas Asterias amurenis had the lowest CAEP content of 1.9 ± 0.6 mg/g dry weight. The most common molecule was CAEP (d19:3–16:0). Additionally, statistical analysis revealed that five aquatic products can be effectively distinguished from their CAEP species; thus, CAEP molecules can play an important role in identifying processed products from aquatic products.

Fatty Acid, Lipid Classes and Phospholipid Molecular Species Composition of the Marine Clam Meretrix lyrata (Sowerby 1851) from Cua Lo Beach, Nghe An Province, Vietnam.

This study aims to analyze compositions of fatty acids and phospholipid molecular species in the hard clams Meretrix lyrata (Sowerby, 1851) harvested from Cua Lo beach, Nghe An province, Viet Nam. Total lipid of hard clams Meretrix lyrata occupied 1.7 ± 0.2% of wet weight and contained six classes: hydrocarbon and wax (HW), triacylglycerol (TAG), free fatty acids (FFA), sterol (ST), polar lipid (PoL), and monoalkyl diacylglycerol (MADAG). Among the constituents, the proportion of PoL accounted was highest, at 45.7%. In contrast, the figures for MADAG were lowest, at 1.3%. Twenty-six fatty acids were identified with the ratios of USAFA/SAFA was 2. The percentage of n-3 PUFA (ω-3) and n-6 PUFA (ω-6) was high, occupying 38.4% of total FA. Among PUFAs, arachidonic acid (AA, 20:4n-6), eicosapentaenoic acid (EPA, 20:5n-3), docosapentaenoic acid (DPA, 22:5n-3), and docosahexaenoic acid (DHA, 22:6n-3) accounted for 3.8%, 7.8%, 2.2% and 12.0% of total lipid of the clam respectively. Phospholipid molecular species were identified in polar lipids of the clams consisting six types: phosphatidylethalnolamine (PE, with 28 molecular species), phosphatidylcholine (PC, with 26 molecular species), phosphatidylserine (PS, with 18 molecular species), phosphatidylinositol (PI, with 10 molecular species), phosphatidylglycerol (PG, with only one molecular species), and ceramide aminoethylphosphonate (CAEP, with 15 molecular species). This is the first time that the molecular species of sphingophospholipid were determined, in Meretrix lyrata in particular, and for clams in general. Phospholipid formula species of PE and PS were revealed to comprise two kinds: Alkenyl acyl glycerophosphoethanolamine and Alkenyl acyl glycerophosphoserine occupy 80.3% and 81.0% of total PE and PS species, respectively. In contrast, the percentage of diacyl glycero phosphatidylcholine was twice as high as that of PakCho in total PC, at 69.3, in comparison with 30.7%. In addition, phospholipid formula species of PI and PG comprised only diacyl glycoro phospholipids. PE 36:1 (p18:0/18:1), PC 38:6 (16:0/22:6), PS 38:1 (p18:0/20:1), PI 40:5 (20:1/20:4), PG 32:0 (16:0/16:0) and CAEP 34:2 (16:2/d18:0) were the major molecular species.

Sphingoid bases of dietary ceramide 2-aminoethylphosphonate, a marine sphingolipid, absorb into lymph in rats

Various functions of dietary sphingolipids have been reported; however, little is known about marine sphingolipids. Ceramide 2-aminoethylphosphonate (CAEP), an abundant sphingolipid in marine mollusks, frequently has a unique triene type of sphingoid base [2-amino-9-methyl-4,8,10-octadecatriene-1,3-diol (d19:3)]. We previously reported that dietary CAEP prepared from the skin of squid was digested in the intestinal mucosa of mice via ceramides to yield free sphingoid bases. How dietary CAEP is then used in the body remains unclear. Here, we investigated the absorption of dietary CAEP using a lipid absorption assay on the lymph collected from rats with thoracic duct cannulation. Our results reveal that sphingoid bases derived from CAEP, including d16:1, d18:1, and d19:3, were detected in the lymph after administration of CAEP. Lymphatic recovery of d19:3 was lower than that of other sphingoid bases. A large fraction of the absorbed sphingoid bases was present as complex sphingolipids, whereas a smaller portion was present in the free form. Fatty acids in ceramide moieties found in the lymph were partially different from dietary CAEP, which indicates that sphingoid bases derived from CAEP could be, at least in part, resynthesized into complex sphingolipids. Future studies should elucidate the metabolism of sphingoid bases derived from CAEP.

Study of Total Lipidome of the Sinularia siaesensis Soft Coral

The rapid development of lipidomics of human and higher animals stimulated the study of the lipidome of certain groups of marine organisms. Soft corals are an integral part of the tropical and cold-water ecosystems of the World Ocean, but there is almost no data on the lipidome of these animals. The total lipidome of a tropical soft coral Sinularia siaesensis (Cnidaria: Anthozoa: Octocorallia: Alcionacea) containing intracellular symbiotic microalgae (zooxanthellae) was studied by gas and liquid chromatography-mass spectrometry. The structure and content of 144 molecular species of the main classes of acyl lipids of this alcyonaria were determined, including waxes, triglycerides (TG), monoalkyldiacylglycerides (MADAG), ethanolamine, choline, serine, and inositol glycerophospholipids (PE, PC, PS, and PI), ceramide aminoethylphosphonate (CAEP), sulfoquinovosyldiacylglyceride (SQDG), and mono- and digalactosyldiacylglycerides (MGDG and DGDG). The main components of S. siaesensis lipids were waxes 16:0/16:0, 16:0/18:0, and 18:0/16:0; TG 16:0/16:0/16:0 and 16:2/16:0/16:0; MADAG 18:0e/16:0/16:0, 16:0e/16:0/18:0, and 16:0e/16:0/16:0; and PS 18:0e/24:5, lyso-PC 18:0e, PE 18:1e/20:4, PC 18:0e/20:4, CAEP 18:2b/16:0, SQDG 14:0/16:0, and PI 18:0/24:5. The dominance of saturated waxes in reserve lipids is a species-specific feature of tropical alcyonarians. Waxes are synthesized in the host organism, and zooxanthellae can increase the proportion of saturated waxes by transferring saturated fatty acids (FA). The residues of polyunsaturated FA (PUFA) are found in the molecules of TG and MADAG, mainly in the sn-1 and sn-2 positions, respectively. Detection of MADAG with residues of marker FA of zooxanthellae (18:0e/18:3/16:0, 18:0e/18:4/16:0, and 16:0e/18:3/16:0) confirms the transfer of PUFA from the symbionts to the host. Tetracosapolyenoic FA, which is a chemotaxonomic markers of octocorals, are concentrated in molecular species of PS and PI. Most molecular species of PE, PC, and PS are in alkylacyl form, while for PI molecules, a diacyl form is characteristic. A significant proportion of MGDG, DGDG, and SQDG points to the importance of zooxanthellae in the formation of the lipid profile of symbiotic soft corals. Determination of the profile of lipid molecular species requires the development of a lipidomic approach in the study of biochemistry and ecology of corals and other cnidarians.

INVESTIGATION ON CONTENT OF FATTY ACIDS, PHOSPHOLIPIDS, AND PHOSPHOLIPID MOLECULAR SPECIES COMPOSITION OF THE VIETNAMESE CORAL Bebryce sp.

In the fatty acid composition of total lipid of the soft coral Bebryce sp., the concentration of unsaturated fatty acid predominates. The composition of saturated fatty acids is very diverse, including all saturated fatty acids from C14 to C26. The unsaturated fatty acids with high concentration are C20: 4n-6, 20:5n-3, 22:6n-3, 24:5n-6, 26:3n-6, 26:2n-6, 26:2n-7, 28:3n-6. In the fatty acids composition of the studied coral, there is presence of characterized fatty acids for the existence of sponges C25-C28 (demospongic fatty acids) with total content 29,86%. Most of the Bebryce coral species do not have zooxanthellae, therefore, in the fatty acids composition, either it is lack or contains only a small amount of markers fatty acids for zooxanthellae such as 18:5n-3, 18:4n-3, 18:3n-6, 20:4n-3. In the phospholipid content of the soft coral Bebryce sp., there is presence of characterized classes for Cnidarian animals such as phosphatidylethanolamine (PE), phosphatidylchonline (PC), phosphatidylserine (PS), phosphatidylinositol (PI), phosphonolipid is ceramide aminoethylphosphonate (CAEP). PC account for the highest concentration (37,20% of total phospholipid). The molecular species of phospholipid classes of Bebryce sp. for the first time were investigated. In the results, there we 60 phospholipid molecular species identified in 5 classes. The molecular species with high content in the classes were PE 20:4/18:1e, PE 20:4/19:1, PC 20:4/18:0e, PC 20:4/16:0e, PS 24:5/18:0e, PI 24:5/18:0, CAEP18:2base/16:0 and CAEP 18:1base/16:0.

Proximate, amino acid and lipid compositions in Sinonovacula constricta (Lamarck) reared at different salinities

Sinonovacula constricta is an economically and nutritionally important bivalve native to the estuaries and mudflats of China, Japan and Korea. In the present study, S. constricta, cultured either under experimental conditions or collected directly from natural coastal areas with different seawater salinities, was investigated for changes in proximates, amino acids and lipids. When culture salinity was increased, levels of moisture, carbohydrate, crude protein and crude lipid were significantly decreased, whereas the level of ash was significantly increased. The level of Ala was increased by 1.5- to 2-fold, whereas the contents of most lipids were significantly decreased, and the proportion of phosphatidylethanolamine was significantly increased. Notably, a high proportion of ceramide aminoethylphosphonates was detected in S. constricta reared at all salinities. The energy content appears to be higher in S. constricta reared at higher salinity. In experimental S. constricta, when the salinity was enhanced, the changes of compositions were very close to those reared at constant high salinity. Sinonovacula constricta reared at higher salinities possesses a superior quality. A short period of exposure to a higher salinity for farmed S. constricta reared at a lower salinity before harvest would be useful with respect to improving its nutritive value. © 2017 Society of Chemical Industry.

Ceramide lipids in alive and thermally stressed mussels: an investigation by hydrophilic interaction liquid chromatography-electrospray ionization Fourier transform mass spectrometry.

Hydrophilic interaction liquid chromatography coupled to electrospray ionization-Fourier transform mass spectrometry was employed to study ceramide lipids occurring in mussels of sp. Mytilus galloprovincialis. Lipid extracts from alive mussels and mussels deliberately subjected to specific thermal treatments were analyzed. In particular, single and tandem MS measurements were performed on a hybrid quadrupole-Orbitrap mass spectrometer and then complemented by MS(n) analyses (n = 2, 3) achieved by a linear ion trap mass spectrometer. This approach enabled the characterization of 66 ceramide lipids, encompassing ceramide phosphoethanolamines (CPE), ceramide aminoethylphosphonates (CAEP) and N-monomethylated CAEP. The sphingoid and acyl chains of each ceramide lipid could be distinctly recognized in terms of numbers of carbon atoms and C=C bonds, and indications on the possible location of the latter on the sphingoid chain could be often inferred from fragmentation patterns. The occurrence of several species hydroxylated on the α carbon of the acyl chain was also discovered. On the other hand, the sphingoid chain of ceramide lipids was never found to be involved in oxidation processes, unless forced exposure of the mussel lipid extracts to atmospheric oxygen was performed. CPE(d19:3/16:0) and its hydroxylated form, CPE(d19:3/2-OH-16:0), were found to be the prevailing species among CPE, whereas CAEP(d18:2/16:0), CAEP(d19:3/16:0) and CAEP(d19:3/2-OH-16:0) were the most abundant CAEP. Finally, ceramide lipids showed a remarkably higher stability, compared with glycerophospholipids, in mussels subjected to different thermal treatments. This finding opens interesting perspectives on the role of ceramide-based lipids in the adaptation of aquatic organisms to thermal stresses. Copyright © 2016 John Wiley & Sons, Ltd.

Lipid Profile in Different Parts of Edible Jellyfish Rhopilema esculentum.

Jellyfish Rhopilema esculentum has been exploited commercially as a delicious food for a long time. Although the edible and medicinal values of R. esculentum have gained extensive attention, the effects of lipids on its nutritional value have rarely been reported. In the present of study, the lipid profile including lipid classes, fatty acyl compositions, and fatty acid (FA) positions in lipids from different parts (oral arms, umbrella, and mouth stalk) of R. esculentum was explored by ultraperformance liquid chromatography--electrospray ionization--quadrupole time-of-flight mass spectrometry (UPLC-ESI-Q-TOF-MS). More than 87 species from 10 major lipid classes including phosphatidylcholine (PC), lysophosphatidylcholine (LPC), phosphatidylethanolamine (PE), lysophosphatidylethanolamine (LPE), phosphatidylinositol (PI), lysophosphatidylinositol (LPI), phosphatidylserine (PS), ceramide (Cer), ceramide 2-aminoethylphosphonate (CAEP), and triacylglycerol (TAG) were separated and characterized. Semiquantification of individual lipid species in different parts of R. esculentum was also conducted. Results showed that glycerophospholipids (GPLs) enriched in highly unsaturated fatty acids (HUFAs) were the major compenents in all parts of R. esculentum, which accounted for 54-63% of total lipids (TLs). Considering the high level of GPLs and the FA compositions in GPLs, jellyfish R. esculentum might have great potential as a health-promoting food for humans and as a growth-promoting diet for some commercial fish and crustaceans. Meanwhile, LPC, LPE, and LPI showed high levels in oral arms when compared with umbrella and mouth stalk, which may be due to the high proportion of phospholipase A2 (PLA2) in oral arms. Moreover, a high CAEP level was detected in oral arms, which may render cell membranes with resistance to chemical hydrolysis by PLA2. The relatively low TAG content could be associated with specific functions of oral arms.

Fatty acid, lipid class, and phospholipid molecular species composition of the soft coral Xenia sp. (Nha Trang Bay, the South China Sea, Vietnam).

The soft corals of the genus Xenia are common for Indo-Pacific reef ecosystems. Lipid class, fatty acid (FA), phospho- and phosphonolipid molecular species compositions were identified for the first time in the soft coral Xenia sp. from Vietnam. Total lipids consisted predominantly of waxes, monoalkyl diacylglycerols, triacylglycerols, sterols, and polar lipids (21.4, 7.7, 14.2, 10.5, and 36.7 %, respectively). Sesquiterpene alcohol, valerenenol, was found. Acids 16:0, 18:3n-6, 20:4n-6, and 20:5n-3 dominated in total FA. The markers of zooxanthellae (18:4n-3 and 18:5n-3) and octocorals (24:5n-6 and 24:6n-3) were detected. Acids 18:5n-3, 20:4n-6, 22:4n-6, and 24:5n-6 concentrated in FA of polar lipids, whereas 14:0, 16:0, 16:1n-7, 18:2n-6, and 18:3n-6 were the major FA of neutral lipids. ChoGpl, EtnGpl, SerGpl, CAEP, PtdIns, and lyso ChoGpl constituted 39.5, 20.8, 20.5, 9.7, 4.3, and 5.3 %, respectively, of the sum of phospho- and phosphonolipids. Thirty-two molecular species of phospholipids and ceramide aminoethylphosphonate (CAEP) were determined by high resolution tandem mass spectrometry. Lyso 18:0e PakCho (4.1 %), 18:0e/20:4 PakCho (20.5 %), 18:1e/20:4 PlsEtn (18.0 %), 18:0e/24:5 PakSer (14.0 %), and 16:0 CAEP (9.6 %) were the major molecular species. EtnGpl and PtdIns mainly consisted of alkenyl acyl and diacyl forms, respectively. Alkyl acyl forms predominated in ChoGpl and SerGpl. Acid 24:5n-6 was a principal FA in SerGpl, whereas 20:4n-6 was more abundant in ChoGpl and EtnGpl. PtdIns contained various C20-24 PUFA. In the context of chemotaxonomy of corals, Xenia sp. has the lipid composition typical for soft corals and the FA profile similar to that of alcyonarians with the high level of 18:3n-6.

Lipids and fatty acids of nudibranch mollusks: potential sources of bioactive compounds.

The molecular diversity of chemical compounds found in marine animals offers a good chance for the discovery of novel bioactive compounds of unique structures and diverse biological activities. Nudibranch mollusks, which are not protected by a shell and produce chemicals for various ecological uses, including defense against predators, have attracted great interest for their lipid composition. Lipid analysis of eight nudibranch species revealed dominant phospholipids, sterols and monoalkyldiacylglycerols. Among polar lipids, 1-alkenyl-2-acyl glycerophospholipids (plasmalogens) and ceramide-aminoethyl phosphonates were found in the mollusks. The fatty acid compositions of the nudibranchs differed greatly from those of other marine gastropods and exhibited a wide diversity: very long chain fatty acids known as demospongic acids, a series of non-methylene-interrupted fatty acids, including unusual 21:2∆7,13, and an abundance of various odd and branched fatty acids typical of bacteria. Symbiotic bacteria revealed in some species of nudibranchs participate presumably in the production of some compounds serving as a chemical defense for the mollusks. The unique fatty acid composition of the nudibranchs is determined by food supply, inherent biosynthetic activities and intracellular symbiotic microorganisms. The potential of nudibranchs as a source of biologically active lipids and fatty acids is also discussed.