Dominant Lipid Class Research Articles

A comparative lipid profile of four fish species: From muscle to industrial by-products based on RPLC−Q-TOF-MS/MS

Fish are crucial for the fishing industry and essential nutrient provision, including lipids. This study employed a high-throughput lipidomic approach to evaluate and contrast the lipid profiles of three marine fish species (P. crocea, S. fuscens, and C. saira) and one freshwater species (H. molitrix) across head, muscle, and viscera. Over 1000 molecular lipid species across 17 subclasses were identified. Notably, acylated monogalactosyldiacylglycerol (acMGDG) was detected for the first time in these species, with a high prevalence of saturated fatty acids (44.7 %−87.7 %). Glycerolipids (67.7 − 86.3 %) and PLs (10.7 − 31.8 %) were identified as the dominant lipid classes. Marine fish muscles displayed higher PL content than freshwater species, and P. crocea viscera contained over 30 % PLs of total lipids. In particular, ether phosphatidyl ethanolamine incorporated more DHA than ether phosphatidylcholine. The viscera of four fish species also exhibited a significant abundance of diacylglycerol (DG), indicating their potential as functional lipid sources. Multivariate analysis identified triglyceride (TG) (59:13), DG (16:1/22:5), and MGDG (16:0/18:2) as potential biomarkers for differentiating among fish anatomical parts. This study deepens the understanding of the nutritional values of these fish, providing guidance for consumer dietary choices and paving the way for transforming previously underutilized by-products into resources with high-value potential.

The effect of nutrient limitation on bacterial wax ester production

Nutrient limitation is widely employed to alter the behaviour of micro-organisms. Here, the impact of nitrogen and, for the first time, phosphate limitation is investigated on the production of bacterial storage lipids; specifically wax esters, a class of storage lipids of industrial interest, by the bacterium Acinetobacter baylyi ADP1 grown on the low-cost substrate acetate. Studies determined the absolute and temporal effects of nutrient limitation and identified a maximum wax titre of 132 mg/L and content of 17 % of biomass. A 4-fold increase in wax production was achievable by manipulating carbon: phosphate ratio. Multivariable analysis identified a novel interaction effect between carbon: nitrogen and carbon: phosphate ratios on wax production. Extreme phosphate starvation shifted the dominant lipid class from wax esters to triacylglycerols, the first report of the potential of phosphate limitation to alter the type of lipid generated. These findings offer valuable insights for future microbial bioproduction studies.

Oxidative stress is inhibited by plant-based supplements: A quantitative lipidomic analysis of antioxidant activity and lipid compositional change

Dietary supplements containing plant extracts are often marketed as having antioxidant properties. Using complex lipid mixtures derived from cellular tissue, we perform a targeted lipidomic assessment of the antioxidant activity of five plant extract supplements. Formulations derived from grape seed, milk thistle, pine bark, turmeric and hawthorn extract were evaluated. Overall, we find evidence to suggest that all supplements suppressed in vitro lipid oxidation to some degree. Suppression of oxidation was most effective in the dominant lipid classes, phosphatidylcholine (PC) and phosphatidylethanolamine (PE), which contain significant numbers of polyunsaturated lipids. Under the conditions of study, grape seed extract supplement was the most effective antioxidant showing statistically significant suppression of lipid oxidation in 11 of the 15 lipid classes quantified. Lipid compositional changes and metrics such as the PC: PE ratio and the double bond index were determined to provide an insight into the effect of oxidative stress and antioxidants on collective membrane properties. Finally, the likely stress that in vivo lipid oxidation could cause to cells, and the mitigating effects of supplements in this context, is also discussed.

Comprehensive evaluation of lipidomics profiles in golden threadfin bream (Nemipterus virgatus) and its by-products using UHPLC-Q-exactive Orbitrap-MS

Golden threadfin bream (Nemipterus virgatus) has become the second-largest surimi processing resource, but little is known about its lipidomics profiles. A comprehensive lipidomics analysis of golden threadfin bream and its by-products was performed. The results showed that golden threadfin bream contained high levels of phospholipid (4.54%–13.13% of total lipids), saccharolipid (5.22%–18.68%), docosahexaenoic acid (DHA, 11.07–21.54% of total fatty acids), eicosapentaenoic acid (EPA, 3.89–5.29%) and arachidonic acid (ARA, 2.36–3.64%). DHA tended to concentrate more on phospholipid than triacylglycerol and other lipid classes. Interestingly, DHA was mainly bonded to the sn-2 position of triacylglycerol and sn-1 position of phospholipid. Additionally, 1400 lipid molecular species belonging to 28 subclasses were identified by ultrahigh-performance liquid chromatography equipped with quadrupole-exactive orbitrap mass spectrometry (UHPLC-Q-Exactive Orbitrap-MS), and glycerolipid was the dominant lipid class. Glycerophospholipid and sphingolipid in fish head and viscera were relatively higher than muscle and skin. Furthermore, the chemometric models were used to differentiate and evaluate the four tissues, and 57 potential lipid biomarkers were screened. Hence, this study will contribute to comprehensively assess the nutritional value of golden threadfin bream and facilitate the high-value utilization of its by-products.

SARS-CoV-2 exploits host DGAT and ADRP for efficient replication

Coronavirus Disease 2019 (COVID-19) is predominantly a respiratory tract infection that significantly rewires the host metabolism. Here, we monitored a cohort of COVID-19 patients’ plasma lipidome over the disease course and identified triacylglycerol (TG) as the dominant lipid class present in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced metabolic dysregulation. In particular, we pinpointed the lipid droplet (LD)-formation enzyme diacylglycerol acyltransferase (DGAT) and the LD stabilizer adipocyte differentiation-related protein (ADRP) to be essential host factors for SARS-CoV-2 replication. Mechanistically, viral nucleo capsid protein drives DGAT1/2 gene expression to facilitate LD formation and associates with ADRP on the LD surface to complete the viral replication cycle. DGAT gene depletion reduces SARS-CoV-2 protein synthesis without compromising viral genome replication/transcription. Importantly, a cheap and orally available DGAT inhibitor, xanthohumol, was found to suppress SARS-CoV-2 replication and the associated pulmonary inflammation in a hamster model. Our findings not only uncovered the mechanistic role of SARS-CoV-2 nucleocapsid protein to exploit LDs-oriented network for heightened metabolic demand, but also the potential to target the LDs-synthetase DGAT and LDs-stabilizer ADRP for COVID-19 treatment.

A comprehensive biochemical characterization of settlement stage leptocephalus larvae of bonefish (Albula vulpes).

Little is known about early development of the near-threatened bonefish (Albula vulpes), a member of superorder Elopomorpha. Members of Elopomorpha are partially defined by their synapomorphic leptocephalus larval stage, for which the nutritional requirements are not well understood. Characterizing the nutritional profile, including major nutrients (such as lipids) used for energetic processes, can help to gain a better understanding of the nutritional requirements for leptocephalus larvae. A total of 24 settlement stage A. vulpes leptocephalus larvae were collected at Long Caye Island, Belize. Samples were used to determine various biochemical characteristics including lipid class, fatty acid and glycosaminoglycan compositions. Each of these biochemical components plays a role in early developmental processes such as cellular membrane formation and is crucial for healthy development. Biochemical characteristics of settlement stage A. vulpes leptocephalus are presented in this study for the first time. The dominant lipid classes and fatty acids detected in these samples were consistent with prior studies using closely related species like the Japanese eel, indicating possible similarities in diets at this stage. In the future, similar analyses can be applied to other species that share the leptocephalus life stage to determine if nutritional requirements at this stage of development are unique to this species. The findings in this study will also help to facilitate the establishment of adequate aquaculture systems for captive bonefish, ultimately leading to improved management strategies for wild bonefish habitats.

Lipid profiles of autophagic structures isolated from wild type and Atg2 mutant Drosophila

Autophagy is mediated by membrane-bound organelles and it is an intrinsic catabolic and recycling process of the cell, which is very important for the health of organisms. The biogenesis of autophagic membranes is still incompletely understood. In vitro studies suggest that Atg2 protein transports lipids presumably from the ER to the expanding autophagic structures. Autophagy research has focused heavily on proteins and very little is known about the lipid composition of autophagic membranes. Here we describe a method for immunopurification of autophagic structures from Drosophila melanogaster (an excellent model to study autophagy in a complete organism) for subsequent lipidomic analysis. Western blots of several organelle markers indicate the high purity of the isolated autophagic vesicles, visualized by various microscopy techniques. Mass spectrometry results show that phosphatidylethanolamine (PE) is the dominant lipid class in wild type (control) membranes. We demonstrate that in Atg2 mutants (Atg2−), phosphatidylinositol (PI), negatively charged phosphatidylserine (PS), and phosphatidic acid (PA) with longer fatty acyl chains accumulate on stalled, negatively charged phagophores. Tandem mass spectrometry analysis of lipid species composing the lipid classes reveal the enrichment of unsaturated PE and phosphatidylcholine (PC) in controls versus PI, PS and PA species in Atg2−. Significant differences in the lipid profiles of control and Atg2− flies suggest that the lipid composition of autophagic membranes dynamically changes during their maturation. These lipidomic results also point to the in vivo lipid transport function of the Atg2 protein, pointing to its specific role in the transport of short fatty acyl chain PE species.

Detailed Analysis of Lipids in Edible Viscera and Muscles of Cooked Crabs Portunus trituberculatus and Portunus pelagicus

ABSTRACTThe lipid profiles, including lipid classes, phospholipid (PL) classes, fatty acid (FA) composition, and glycerophospholipid (GP) molecular species, in the two edible parts (edible viscera and muscles) of two species of cooked crabs (Portunus trituberculatus and Portunus pelagicus) were systematically characterized for the first time to reveal their nutritional values. For the muscles, PL (66.84–82.23% of total lipids) was the major component of lipids. While for the edible viscera, triacylglycerol (79.04–96.66% of total lipids) was the dominant lipid class. For all lipid samples, eicosapentaenoic acid (EPA) (3.47–22.02% of total FA) and docosahexaenoic acid (DHA) (7.30–16.52% of total FA) were the predominant FAs. Among PL from the crab muscles, phosphocholine (61.51–63.27 mol%) and phosphoethanolamine (21.58–23.43 mol%) were abundant. About 250 GP molecular species belonging to six classes, including glycerophosphocholine, lysoglycerophosphocholine, glycerophosphoethanolamine, lysoglycerophosphoethanolamine, glycerophosphoserine, and lysoglycerophosphoserine, were identified in crab muscles using direct infusion mass spectrometric method. A majority of the dominant molecular species of GP contained omega-3 polyunsaturated fatty acid, especially EPA and DHA. The useful information obtained in this study makes it possible to use crab lipid for producing higher value-added products for commercial exploitation.

Spatio-temporal variability of biomarker responses and lipid composition of Marphysa sanguinea, Montagu (1813) in the anthropic impacted lagoon of Tunis

In this study the Polychaeta Marphysa sanguinea, was tested to investigate the impact of metal pollution on the environmental state of a coastal Mediterranean lagoon, Tunis Lagoon (Tunisia). A multi-biomarker approach comprising glutathione-stransferase, cyclooxygenase, lysozyme activity, and lipid class composition of the Polychaeta was employed on a seasonal basis in the present investigation. The multivariate statistical approach (principal component analysis and Pearson correlation) clearly demonstrated different spatial patterns in biomarker values and lipid class concentrations. The phospholipids were the dominant lipid class in M. sanguinea, with the highest value found at the control station. The impact of pollution was most clearly observed on the main storage lipid class, triacylglycerol, which was lowest in the most impacted sites. Our work suggests that M. sanguinea can be used in warmer Mediterranean costal habitats as a sentinel species of contaminated ecosystems.

Functional diversity and nutritional content in a deep-sea faunal assemblage through total lipid, lipid class, and fatty acid analyses.

Lipids are key compounds in marine ecosystems being involved in organism growth, reproduction, and survival. Despite their biological significance and ease of measurement, the use of lipids in deep-sea studies is limited, as is our understanding of energy and nutrient flows in the deep ocean. Here, a comprehensive analysis of total lipid content, and lipid class and fatty acid composition, was used to explore functional diversity and nutritional content within a deep-sea faunal assemblage comprising 139 species from 8 phyla, including the Chordata, Arthropoda, and Cnidaria. A wide range of total lipid content and lipid class composition suggested a diversified set of energy allocation strategies across taxa. Overall, phospholipid was the dominant lipid class. While triacylglycerol was present in most taxa as the main form of energy storage, a few crustaceans, fish, jellyfishes, and corals had higher levels of wax esters/steryl esters instead. Type and amount of energy reserves may reflect dietary sources and environmental conditions for certain deep-sea taxa. Conversely, the composition of fatty acids was less diverse than that of lipid class composition, and large proportions of unsaturated fatty acids were detected, consistent with the growing literature on cold-water species. In addition, levels of unsaturation increased with depth, likely suggesting an adaptive strategy to maintain normal membrane structure and function in species found in deeper waters. Although proportions of n-3 fatty acids were high across all phyla, representatives of the Chordata and Arthropoda were the main reservoirs of these essential nutrients, thus suggesting health benefits to their consumers.

Seasonal and interannual variation in the lipid content and composition of Euphausia superba Dana, 1850 (Euphausiacea) samples derived from the Scotia Sea fishery

The Antarctic krill (Euphausia superba Dana, 1850) is an important trophic link between phytoplankton and higher trophic levels. Knowledge of the lipid biochemistry of krill assists in understanding their seasonal biology and predicting their responses to ecological changes. We collected daily samples of krill from a commercial fishing vessel operating in the Atlantic Sector of the Southern Ocean from 2014 to 2016. We analysed the total lipid content of krill sampled every two weeks and the relative distribution of lipid class levels to examine seasonal trends. Krill total lipid content varied significantly within and between seasons and sexes. An annual sinusoidal trend was seen in total lipid content with the highest values in autumn and the lowest in spring (average 380 and 87 mg/g dry mass, respectively). Total lipids in krill increased during summer, peaking in autumn, with the total lipids in winter individuals decreasing towards spring. The relative distribution of lipid class levels varied between season and year. Levels of triacylglycerol showed the same seasonal trend as total lipid content, whilst phospholipid showed the inverse trend indicating the contrasting roles of these two dominant lipid classes. These data provide high-resolution information on the seasonality of krill lipid content and composition. This information has both ecological and commercial utility. ​

High Arachidonic Acid Levels in the Tissues of Herbivorous Fish Species (Siganus fuscescens, Calotomus japonicus and Kyphosus bigibbus).

The lipid and fatty acid compositions in the various organs (muscle, liver, other viscera) and stomach contents of three common herbivorous fish species in Japan, Siganus fuscescens, Calotomus japonicus and Kyphosus bigibbus, were examined to explore the stable 20:4n-6 (arachidonic acid, ARA) sources. Triacylglycerol (TAG), phosphatidylethanolamine (PtdEtn), and phosphatidylcholine (PtdCho) were the dominant lipid classes, while the major FA contents were 16:0, 18:1n-9, 16:1n-7, 14:0, 18:0, 18:1n-7, and some PUFA, including ARA, 20:5n-3 (eicosapentaenoic acid, EPA), 22:5n-3 (docosapentaenoic acid, DPA), and 22:6n-3 (docosahexaenoic acid, DHA). The amounts of these fatty acids were varied among species and their lipid classes. Phospholipids contained higher levels of PUFA than TAG. However, ARA in both phospholipids and TAG was markedly present in the muscle and viscera of all specimens, particularly in C. japonicus and K. bigibbus. Moreover, their ARA levels were higher than the levels of DHA and EPA. The observed high ARA level is unusual in marine fish and might be characteristic of herbivorous fish. Furthermore, ARA was the dominant PUFA in the stomach contents of the three species, suggesting that the high ARA level originated from their food sources. The above indicates that these three herbivorous fishes are ARA-rich marine foods and have potential utilization as stable ARA resources.

Lipid characterization of red alga Rhodymenia pseudopalmata (Rhodymeniales, Rhodophyta)

SUMMARY Rhodymenia pseudopalmata is a red alga that grows at the Caribbean coast of the Yucatan Peninsula and has been proven successful in cultivation. In this study we present the lipid composition of R. pseudopalmata collected from wild populations during three different seasons of 2013. Cultured material was also analyzed and compared in order to evaluate its value as feedstock for biotechnological uses. Thin layer chromatography, 1 H and 13 C NMR spectroscopy and gas chromatography‐mass spectrometry were used to assess variations in their lipid composition. Our results showed that the dominant lipid classes were phospholipids both in wild and cultured materials. The phospholipids phosphatidylcholine and phosphatidylglycerol and the glycolipid monogalactosyldiacylglycerol were present in both wild and cultured R. pseudopalmata, whereas the phospholipid lysophosphatidylcholine was only found in wild material. Fatty acids (FAs) showed a high monounsaturated FAs (MUFAs) content with oleic acid (C18:1ω9) as the dominant compound (78 and 94% of the MUFAs for wild and culture materials, respectively). Saturated FAs (SFAs) represented approximately 90% of the total fatty acid content, with palmitic acid (C16:0) reaching approximately 83% of the SFA content. Rhodymenia pseudopalmata was low in polyunsaturated FAs when compared to other red algae. Other compounds such as 1‐heptadecene, 1‐hexadecene, 15‐heptadecenal, 3‐eicosene 6,10,14‐trimethyl‐2‐pentadecanone, phytol, and heptadecane were also found. Lipid composition differences between the wild and cultured algae suggest that light and nutrients can be manipulated to modify lipid composition. Based on its lipid composition and cultivation feasibility, R. pseudopalmata could be a potential source for nutraceuticals and biofuels production.

Annual cycle of lipid content and lipid class composition in zooplankton from the Beaufort Sea shelf, Canadian Arctic

We determined seasonal cycles of lipid content, lipid class composition, and carbon and nitrogen content of seven taxa of zooplankton that were collected from the Beaufort Sea shelf, Canadian Arctic, over a 10-month period (September 2003 – August 2004). All taxa except the chaetognath Parasagitta elegans had substantial lipids stores (>50%), either seasonally (Oikopleura spp.) or throughout the year (Calanus hyperboreus, Calanus glacialis, Paraeuchaeta glacialis, Metridia longa, and Eukrohnia hamata). Wax esters were the dominant lipid class in the chaetognath Eukrohnia hamata and in all copepods, including the carnivore Paraeuchaeta glacialis. Seasonal trends in lipid content and composition varied among taxa; some taxa had little variation from winter through summer (e.g., Parasagitta elegans), other taxa showed little variation until summer (e.g., Calanus glacialis), and others showed increasing or decreasing trends during winter and spring (e.g., Calanus hyperboreus). Specifically, total lipid content of Calanus hyperboreus decreased from January through May at a rate of ∼450 μg·month−1·individual−1in adult females and ∼100 μg·month−1·individual−1in juvenile copepodite IV, representing a 75%–85% loss in lipid.

Fatty Acid and Lipid Profiles with Emphasis on n-3 Fatty Acids and Phospholipids from Ciona intestinalis.

In order to establish Ciona intestinalis as a new bioresource for n-3 fatty acids-rich marine lipids, the animal was fractionated into tunic and inner body tissues prior to lipid extraction. The lipids obtained were further classified into neutral lipids (NL), glycolipids (GL) and phospholipids (PL) followed by qualitative and quantitative analysis using GC-FID, GC-MS, (1)H NMR, 2D NMR, MALDI-TOF-MS and LC-ESI-MS methods. It was found that the tunic and inner body tissues contained 3.42-4.08% and 15.9-23.4% of lipids respectively. PL was the dominant lipid class (42-60%) irrespective of the anatomic fractions. From all lipid fractions and classes, the major fatty acids were 16:0, 18:1n-9, C20:1n-9, C20:5n-3 (EPA) and C22:6n-3 (DHA). The highest amounts of long chain n-3 fatty acids, mainly EPA and DHA, were located in PL from both body fractions. Cholestanol and cholesterol were the dominant sterols together with noticeable amounts of stellasterol, 22 (Z)-dehydrocholesterol and lathosterol. Several other identified and two yet unidentified sterols were observed for the first time from C. intestinalis. Different molecular species of phosphatidylcholine (34 species), sphingomyelin (2 species), phosphatidylethanolamine (2 species), phosphatidylserine (10 species), phosphatidylglycerol (9 species), ceramide (38 species) and lysophospholipid (5 species) were identified, representing the most systematic PL profiling knowledge so far for the animal. It could be concluded that C. intestinalis lipids should be a good alternative for fish oil with high contents of n-3 fatty acids. The lipids would be more bioavailable due to the presence of the fatty acids being mainly in the form of PL.

Changes in the nutritional composition of captive early-mid stage Panulirus ornatus phyllosoma over ecdysis and larval development

Abstract Elucidation of the key nutritional requirements for complete larval development of the tropical spiny rock lobster, Panulirus ornatus, presents a major challenge for the development of robust commercial aquaculture for this crustacean. As a foundation study in this area, the chemical composition of early–mid stage P. ornatus phyllosoma (Stages I–VI) receiving a novel formulated diet was analysed immediately prior and post-ecdysis to provide insight into the crude nutritional trends during the larval development cycle. From the onset of moulting, cyclical patterns were evident in the proximate composition of phyllosoma, resulting in substantial restructuring between the pre- and post-moult stages of the moult cycle. Proportions of protein, lipid and ash were high at the premoult stage, reflecting growth and nutrient accumulation over the intermoult period, and reduced at the post-moult stage, reflecting the large uptake of water to facilitate subsequent growth. Polar lipid was the dominant lipid class, accounting for > 90% of the total lipid content. Conversely, triacylglycerol concentrations were low (

Comprehensive Analysis of Lipid Composition in Crude Palm Oil Using Multiple Lipidomic Approaches

Palm oil is currently the leading edible oil consumed worldwide. Triacylglycerol (TAG) and diacylglycerol (DAG) are the dominant lipid classes in palm oil. Other lipid classes present in crude palm oil, such as phospholipids and galactolipids, are very low in abundance. These low-abundance lipids constitute key intermediates in lipid biosynthesis. In this study, we applied multiple lipidomic approaches, including high-sensitivity and high-specificity multiple reaction monitoring, to comprehensively quantify individual lipid species in crude palm oil. We also established a new liquid chromatography-coupled mass spectrometry method that allows direct quantification of low-abundance galactolipids in palm oil without the need for sample pretreatment. As crude palm oil contains large amounts of neutral lipids, our direct-detection method circumvents many of the challenges encountered with conventional lipid quantification methods. This approach allows direct measurement of lipids with no hassle during sample preparation and is more accurate and precise compared with other methods.

Sebaceous Lipid Profiling of Bat Integumentary Tissues: Quantitative Analysis of Free Fatty Acids, Monoacylglycerides, Squalene, and Sterols

White-nose syndrome (WNS) is a fungal disease caused by Pseudogymnoascus destructans and is devastating North American bat populations. Sebaceous lipids secreted from host integumentary tissues are implicated in the initial attachment and recognition of host tissues by pathogenic fungi. We are interested in determining if ratios of lipid classes in sebum can be used as biomarkers to diagnose severity of fungal infection in bats. To first establish lipid compositions in bats, we isolated secreted and integral lipid fractions from the hair and wing tissues of three species: big brown bats (Eptesicus fuscus), Eastern red bats (Lasiurus borealis), and evening bats (Nycticeius humeralis). Sterols, FFAs, MAGs, and squalene were derivatized as trimethylsilyl esters, separated by gas chromatography, and identified by mass spectrometry. Ratios of sterol to squalene in different tissues were determined, and cholesterol as a disease biomarker was assessed. Free sterol was the dominant lipid class of bat integument. Squalene/sterol ratio is highest in wing sebum. Secreted wing lipid contained higher proportions of saturated FFAs and MAGs than integral wing or secreted hair lipid. These compounds are targets for investigating responses of P. destructans to specific host lipid compounds and as biomarkers to diagnose WNS.

Influence of different levels of dissolved oxygen on the success of Greenland halibut (Reinhardtius hippoglossoides) egg hatching and embryonic development

The aim of this study was to determine the influence of different levels of dissolved oxygen (DO) on embryonic development (ED) and hatching success of Greenland halibut (Reinhardtius hippoglossoides) eggs. Fertilized eggs from six females were exposed to five DO levels: severely hypoxic (10 and 20 %sat [percent saturation]), moderately hypoxic (35 and 50 %sat), and normoxic (100 %sat). Greenland halibut eggs were highly tolerant to hypoxia, with hatching occurring at levels as low as 20 %sat. In severely hypoxic conditions (10 %sat), ED was impaired and no hatching occurred. Lipid composition, during ED, changed as a function of female origin and DO levels. Phospholipids were the dominant lipid class in eggs. Although triacylglycerols were a minor lipid class in terms of abundance, they were only used under severe hypoxia. The results suggest that severe hypoxia (between 10 and 20 %sat) has detrimental effect on the early development of Greenland halibut and may result in reduced recruitment and lower population abundance if the decreasing trend in the DO levels observed in the bottom waters of the Gulf of St. Lawrence continues in the future. Other species that share similar life histories may also be at risk.

Analysis of the lipids and molecular speciation of the triacylglycerol of the oils of Luffa cylindrica and Adenopus breviflorus

Oils extracted from seeds of Luffa cylindrica and Adenopus breviflorus were evaluated, in order to study their chemical compositions and lipid profile. Oil content of seed of L. cylindrica was 390.10 ± 0.20 g/kg while that of A. breviflorus was 500.80 ± 0.70 g/kg. Iodine value of L. cylindrica was 147.01 ± 0.70 cg iodine/g while that of A. breviflorus was 126.50 ± 0.50 cg iodine/g. Seed as well as oils of L. cylindrica and A. breviflorus were found rich in K and Ca. C18:2 was the dominant fatty acid found in the oils while neutral lipids were the dominant lipid class. Sitosterol, beta-tocopherol, phytol, stigmasterol, and hydrocarbons were identified in the unsaponifiable matter of the oils using GC–MS. HPLC results revealed presence of glycolipids such as monogalactosyldiacylglycerol, digalactosyldiacylglycerol, and digalactosylmonoacylglycerol. Phosphatidylethanolamine was the dominant phospholipids in the oils. Molecular speciation of triacylglycerol revealed presence of C38 (LLnLn) and C40 (LLLn/LnLnP/LnLnO) to be dominantly present in the oils.