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Background: 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., Results: 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., Conclusion: 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., (© 2017 Society of Chemical Industry.)

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.

Isochrysis galbana is a species of marine microalgae that is principally used to feed the larvae and early juveniles of bivalve mollusks (e.g., ark shells, clams, mussels, oysters and scallops). The artificial hatchery stages of most of these larvae are primarily occur during high-temperature seasons, when the water temperature in the breeding pool frequently exceeds 30 °C and even reaches 35 °C, which may change the lipid composition of I. galbana, thus affecting its nutritional value. In this experiment, we investigated changes in the lipid composition of I. galbana Parke at high temperature using ultra-performance liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry. The results showed that the sulfoquinovosyldiacylglycerol (SQDG), monogalactosyldiacylglycerol (MGDG), diacylglycerylcarboxyhydroxymethylcholine (DGCC) and digalactosyldiacylglycerol (DGDG) contents increased during growth at 20 and 35 °C. Conversely, the lyso-SQDG, lyso-MGDG, lyso-DGDG, lyso-DGCC and triacylglycerol (TAG) contents clearly decreased. Moreover, higher SQDG, MGDG, DGDG and DGCC contents and lower lyso-lipid and TAG contents were observed in I. galbana Parke grown at 35 versus 20 °C. In addition, the content of docosahexaenoic acid (DHA) improved at 20 and 35 °C during growth, and DHA accumulated to greater levels at 35 °C than at 20 °C at the same time points. These results revealed an increase in DHA content as the temperature rose, which indicated that the nutritional value of I. galbana Parke during logarithmic phase improved in the same cultured time with an increasing temperature. [ABSTRACT FROM AUTHOR]

Changes in membrane lipid composition play multiple roles in plant adaptation and survival in the face of chilling and freezing damage. The ultra-performance liquid chromatography/quadrupole-TOF-MS (UPLC/Q-TOF-MS)-based approach was developed for investigating the lipid changes during cold exposure in Stephanodiscus sp. followed by multivariate statistical analysis including principal components analysis, partial least squares discriminant analysis and orthogonal projection on latent structure discriminant analysis for data classification and potential biomarkers selection. The analysis demonstrated dramatic lipid alterations take place in both extraplastidic and plastidic membranes. Thirty-eight lipid molecules were selected and identified as putative biomarkers, including chlorophyll a degradation products, triacylglycerol, phosphatidylcholine, phosphatidylglycerol, sulfo-quinovosyldiacylglycerol, monogalactosyldiacylglyceroll, lyso-phosphatidylglycerol, lyso-phosphatidylcholine, lyso-monogalactosyldiacylglycerol and lyso-sulfoquinovosyldiacylglycerol. These metabolites have been shown previously to function in energy storage, membrane stability and photosynthesis efficiency. This study is the first one using UPLC/Q-TOF-MS-based lipidomic profiling with multivariate statistical analysis to explore the lipidomic changes of microalgae in response to stress conditions, which promotes better understanding of their physiology and ecology. [ABSTRACT FROM AUTHOR]

The serum polar lipid metabolic changes for two common cage-cultured fishes, yellow coraker Pseudosciaena crocea and Japanese seabass Lateolabrax japonicus, after tropical storm attack have been studied by ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-qTOF-MS). The full scan mass spectrometry combined with principal component analysis (PCA) and orthogonal projections to latent structures discriminant analysis (OPLS-DA) indicated that yellow croaker underwent significant chemico-physiological changes during the recovery process, whereas Japanese seabass did not show such noticeable time-dependent consistent metabolites change patterns. Further identification of the metabolite biomarkers showed the increase of phosphatidylcholine with high unsaturated fatty acid and lysophospholipids, and the decrease of phosphatidylcholine with saturated fatty acids and plasmologens, which indicated the need of energy supplement and successive stressful inflammation. The increase of taurocholic acid and decrease of cortol could be regarded as the physiological alleviation measure during the recovery period. This is the first metabolomic study to tackle the fish physiological response for the complex environmental changes, and demonstrated that lipidomics is an effective analytical tool for predicting the stress resistance of fish to ultra uncontrolled environmental stress. [ABSTRACT FROM AUTHOR]

Abstract: The photosynthetic glycerolipids composition of algae is crucial for structural and physiological aspects. In this work, a comprehensive characterization of the photosynthetic glycerolipids of the diatom Stephanodiscus sp. was carried out by ultra performance liquid chromatography–electrospray ionization-quadrupole-time of flight mass spectrometry (UPLC–ESI-Q-TOF MS). By use of the MSE data collection mode, the Q-TOF instrument offered a very viable alternative to triple quadrupoles for precursor ion scanning of photosynthetic glycerolipids and had the advantage of high efficiency, selectivity, sensitivity and mass accuracy. Characteristic fragment ions were utilized to identify the structures and acyl compositions of photosynthetic glycerolipids. Comparing the abundance of fragment ions, it was possible to determine the position of the sn-glycerol-bound fatty acyl chains. As a result, four classes of photosynthetic glycerolipid in the extract of Stephanodiscus sp. were unambiguously identified, including 16 monogalactosyldiacylglycerols (MGDGs), 9 digalactosyldiacylglycerols (DGDGs), 23 sulfoquinovosyldiacylglycerols (SQDGs) and 8 phosphatidylglycerols (PGs). As far as our knowledge, this is the first report on global identification of photosynthetic glycerolipids, including lipid classes, fatty acyl composition within lipids and the location of fatty acids in lipids (sn-1 vs. sn-2), in the extract of marine microalgae by UPLC–ESI-Q-TOF MS directly. [Copyright &y& Elsevier]

The nutritional requirements and metabolism of bivalves remain largely unknown. In this study, we investigated the effects of dietary carbohydrate/lipid ratios on growth performance, body composition, digestive enzyme activities, oxidative status, and transcriptome profile in juvenile razor clam Sinonovacula constricta. Five microcapsule diets with varying levels of carbohydrate (30–45%) and lipid (2–15%) were prepared and designated as C45L2 (45% carbohydrate and 2% lipid), C41L5, C36L8, C33L11, and C30L15 groups. Juvenile S. constricta with an initial shell length of 4.9 mm were fed with these microcapsule diets for 2 weeks. The results showed that the clam in the C33L11 group exhibited the fastest growth rate. The body protein content decreased with the decreasing dietary carbohydrate/lipid ratio. The clam in the C33L11 group showed significantly higher glycogen content compared to the C45L2, C41L5, or C30L5 group. The amylase activity of the clam in the C45L2 and C41L5 group was significantly higher than that in the C36L8, C33L11, and C30L15 group. The clam in the C33L11 group showed significantly higher catalase and superoxide dismutase activities compared to other microcapsule groups. The malondialdehyde level of the clam in the C30L15 group was significantly higher than that in the C45L2, C41L5, and C33L11 group. Transcriptome analysis showed that the autophagy pathway in the clam fed C41L5 was upregulated compared with those fed C33L11. Meanwhile, the protein levels of microtubule-associated protein 1 A/1B-light chain 3 membrane type (LC3-II) in the C41L5 group were also significantly higher than those in the C33L11 group. Moreover, the clam in the C41L5 group exhibited increased phosphorylation levels of the eukaryotic translation initiation factor 4E-binding protein (4E-BP) and decreased phosphorylation levels of the ribosomal protein S6 kinase beta-1 (S6K). Our results revealed that the optimal dietary carbohydrate/lipid ratio for juvenile S. constricta was approximately 3.01. The high-carbohydrate/low-lipid diet may repress the growth of clam by inhibiting mammalian target of rapamycin complex 1 (mTORC1) and subsequently activating autophagy, while the poor growth performance in the low-carbohydrate/high-lipid diet group may be associated with high lipid peroxidation levels in juvenile S. constricta. • The optimal carbohydrate/lipid ratio for juvenile S. constricta was about 3.01. • The body protein content was decreased with the decline of carbohydrate/lipid ratio. • Amylase activity increased with the increase of dietary carbohydrate. • Fit carbohydrate/lipid ratio enhanced SOD, CAT activities, and lower carbohydrate to lipid ratio increased MDA level. • Compared to C33L11 diet, C41L5 diet might lead to autophagy through mTORC1 pathway. [ABSTRACT FROM AUTHOR]