Lipid composition of gametes and embryos of the sea urchin Strongylocentrotus intermedius at early stages of development

Fatty Acids of Echinoderms: Diversity, Current Applications and Future Opportunities

The phylum Echinodermata comprising the classes Asteroidea, Ophiuroidea, Echinoidea, Holothuroidea, and Crinodeia, is one of the important invertebrate groups. Members of this phylum live exclusively in marine habitats and are distributed in almost all depths and latitudes. Some of them, such as sea urchins and sea cucumbers, are commercially valuable and constitute a major fishery resource. Echinoderms are increasingly recognized as a unique source of various metabolites with a wide range of biological activities. The importance of dietary polyunsaturated fatty acids, such as eicosapentaenoic acid, in human health has drawn attention to echinoderms as a promising source of essential fatty acids (FAs). Extensive information on the FAs of the phylum has been accumulated to date. The biosynthetic capabilities and feeding habits of echinoderms explain the findings of the unusual FAs in them. Certain common and unusual FAs may serve as chemotaxonomic markers of the classes. The main goal of the review was to gather the relevant information on the distribution of FAs among the echinoderm classes, describe the structures, distribution, biosynthetic pathways, and bioactivity, with an emphasis on the FAs specific for echinoderms. A large part of the review is devoted to the FAs derived from echinoderms that exhibit various biological activities promising for potential therapeutic applications.

Exposure of adult sea urchin Strongylocentrotus intermedius to stranded heavy fuel oil causes developmental toxicity on larval offspring

Heavy fuel oil (HFO) spills pose serious threat to coastlines and sensitive resources. Stranded HFO that occurs along the coastline could cause long-term and massive damage to the marine environment and indirectly affect the survival of parental marine invertebrates. However, our understanding of the complex associations within invertebrates is primarily limited, particularly in terms of the toxicity effects on the offspring when parents are exposed to stranded HFO. Here, we investigated the persistent effects on the early development stage of the offspring following stranded HFO exposure on the sea urchin Strongylocentrotus intermedius. After 21 d exposure, sea urchins exhibited a significant decrease in the reproductive capacity; while the reactive oxygen species level, 3-nitrotyrosine protein level, protein carbonyl level, and heat shock proteins 70 expression in the gonadal tissues and gametes significantly increased as compared to the controls, indicating that HFO exposure could cause development toxicity on offspring in most traits of larval size. These results suggested that the stranded HFO exposure could increase oxidative stress of gonadal tissues, impair reproductive functions in parental sea urchins, and subsequently impact on development of their offspring. This study provides valuable information regarding the persistent toxicity effects on the offspring following stranded HFO exposure on sea urchins.

Sex-Specific Differences in the Toxic Effects of Heavy Fuel Oil on Sea Urchin (Strongylocentrotus intermedius)

The purpose of this study was to explore and compare the sex-specific differences in the toxic effects of water-accommodated fractions of 380# heavy fuel oil (HFO WAF) on the sea urchin Strongylocentrotus intermedius. Sea urchins were acutely exposed to HFO WAF at different nominal concentrations (0%, 10% and 20%) for seven days. The results showed that females had a higher polycyclic aromatic hydrocarbons (PAHs) bioaccumulation in gonad tissues and that both the total antioxidant capacity (TAC) and lipid peroxidation (LPO) levels in the gonad tissues of females were much higher than those of males. The PAHs bioaccumulation in gametes indicated that parents’ exposure could lead to a transfer of PAHs to their offspring, and eggs had higher TAC and LPO than sperms. After maternal and paternal exposure to HFO WAF, the frequency of morphological abnormalities of the offspring was increased when compared to the control. Overall, these results indicated that maternal exposure to HFO WAF could cause more significantly toxic effects on sea urchins than paternal exposure could, which could lead to more significantly negative effects on their offspring.

Assessment of the biochemical and nutritional values of Venerupis decussata from Tunisian lagoons submitted to different anthropogenic ranks

The present study aimed to evaluate the biochemical status of Venerupis decussata collected seasonally from two Tunisian coastline lagoons (Ghar El Melh and Boughrara) submitted to different anthropogenic levels. Trace elements were significantly higher in clams from Boughrara, especially during the warm season. Fatty acids, proximate compositions, and nutritional value of both clam populations were higher, appearing to be the best for human consumption principally during the spring season. The principal component analysis was determined, including phospholipids and reserve lipids, revealing a great variation with the exogenous and endogenous factors. Generally, clams from Boughrara had a significant alteration in biochemical composition principally due to the anthropogenic levels and physicochemical fluctuation of this lagoon. Our results reflected the healthy benefit of clam consumption and the use of energy reserves and essential fatty acids as a great biomarker to assess ecological risk in lagoons and other coastal ecosystems.

Marine omega-3 (n-3) phospholipids: A comprehensive review of their properties, sources, bioavailability, and relation to brain health

For several decades, there has been considerable interest in marine-derived long chain n-3 fatty acids (n-3 LCPUFAs) due to their outstanding health benefits. n-3 LCPUFAs can be found in nature either in triglycerides (TAGs) or in phospholipid (PL) form. From brain health point of view, PL n-3 is more bioavailable and potent compared to n-3 in TAG form, as only PL n-3 is able to cross the blood-brain barrier and can be involved in brain biochemical reactions. However, PL n-3 has been ignored in the fish oil industry and frequently removed as an impurity during degumming processes. As a result, PL products derived from marine sources are very limited compared to TAG products. Commercially, PLs are being used in pharmaceutical industries as drug carriers, in food manufacturing as emulsifiers and in cosmetic industries as skin care agents, but most of the PLs used in these applications are produced from vegetable sources that contain less (without EPA, DPA, and DHA) or sometimes no n-3 LCPUFAs. This review provides a comprehensive account of the properties, structures, and major sources of marine PLs, and provides focussed discussion of their relationship to brain health. Epidemiological, laboratory, and clinical studies on n-3 LCPUFAs enriched PLs using different model systems in relation to brain and mental health that have been published over the past few years are discussed in detail.

Transgenerational effects of heavy fuel oil on the sea urchin Strongylocentrotus intermedius considering oxidative stress biomarkers

Stranding of oil onto a coastline after an oil spill threatens the health of marine benthic organisms. Here, the transgenerational effects of exposure to stranded heavy fuel oil (HFO) on the sea urchin Strongylocentrotus intermedius were assessed. The column containing gravel coated with HFO was prepared in the laboratory to simulate HFO-contaminated gravel shorelines. Adult sea urchins were exposed for 21 days to either a HFO-oiled gravel column at the oil loading of 3000 μg oil/g gravel or a non-HFO-oiled gravel column (as the control treatment) and then offspring were either exposed to HFO or ambient seawater conditions. The sublethal exposure to HFO for 21 days induced polycyclic aromatic hydrocarbons (PAHs) accumulation in gonads, accompanied by increased levels of oxidative lipid, protein and DNA damage and a reduction in total antioxidant capacity. Analysis of gametes indicated that both maternal and paternal exposure could result in the transfer of PAHs and DNA damage to their offspring. Parental (maternal, paternal or both) exposure to HFO caused increases in malformation rates of offspring compared to those from control parents under ambient seawater condition. Continued HFO exposure in the offspring resulted in further increased malformation rates compared with those reared in ambient seawater, as well as oxidative lipid, protein and DNA damage. Furthermore, mother exposure history reduced the total antioxidant capacity of larvae to response to continued HFO exposure. Overall, the results suggest an increased sensitivity to toxic effects of HFO in larvae from exposed both parents compared with those from control parents in S. intermedius, which may consequently affect the recruitment and population maintenance.

Plasma membrane lipid diffusion and composition of sea urchin egg membranes vary with ocean temperature

A diverse and complex array of lipids plays a vital role in structuring and organizing cell membranes. However, the details of lipid requirements for global membrane organization are poorly understood. One obstacle to this understanding is the difficulty of accurately manipulating the lipid composition of commonly studied mammalian cells. In contrast, the lipid composition of cells of ectotherms changes with changes in environmental temperatures. Thus, comparison of lipid probe diffusion in cells from animals living at different temperatures, together with biochemical analysis, can be used toward understanding membrane organization. We used two dialkyindocarbocyanine iodide (DiI) probes, of differing chain length, to probe lipid organization in terms of their lateral diffusion in eggs of the sea urchin Strongylocentrotus purpuratus. The lateral diffusion of our probes changed in urchins developing in the year of an "El Niño" weather event, which raised the ocean temperature by several degrees, suggesting alterations in membrane domain composition and structure. Indeed the changes in lateral diffusion were correlated with lower levels of unsaturated fatty acids and cholesterol in animals of the "El Niño" year than in animals of the preceding or following years. We found similar trends comparing DiI diffusion in membranes of eggs from 15 degrees C waters with those from 10 degrees C. Our findings establish a new approach for manipulating and studying membrane organization.

Energy metabolism of spermatozoa of the sea urchin Glyptocidaris crenularis

Energy metabolism in spermatozoa of the sea urchin Glyptocidaris crenularis was examined. The spermatozoa contained not only several kinds of phospholipids and cholesterol but also triacylglycerides (TG). Following dilution of the dry sperm in sea water, the TG content decreased rapidly. Other lipids, however, remained at constant levels, except for an increase in the level of free fatty acid. Oil red-O staining of spermatozoa showed that TG was principally located in part of the sperm midpiece. Also, high lipase activity was demonstrated in the spermatozoa. In both intact cells and a cell-free system, 14C-labeled fatty acids were oxidized to 14CO2. It is thus concluded that G. crenularis spermatozoa use TG as a substrate for energy metabolism.

Fatty chain composition of phospholipids in sea urchin spermatozoa

1. An analysis was made of lipids extracted from the spermatozoa of the sea urchins, Hemicentrotus pulcherrimus and Anthocidaris crassispina. 2. Nearly all the lipids from both species consisted of phospholipids (about 80%) and cholesterol (about 14%). Triglyceride and cholesterol ester were present in trace amounts. 3. The fatty acid composition of each phospholipid was determined by gas-liquid chromatography. In both species, the fatty acid consisting of phosphatidylethanolamine was of the unsaturated type for the most part, while cardiolipin was comprised to a considerable degree of saturated fatty acids. In phosphatidylcholine and phosphatidylserine from H. pulcherrimus sperm, unsaturated fatty acid content was somewhat higher than that in phospholipids from A. crassispina sperm.

Changes in triacylglycerol, diacylglycerol and free fatty acids after fertilization in developing toad embryos

The content and fatty-acid composition of triacylglycerols, diacylglycerols and free fatty acids were analyzed from the unfertilized oocyte stage to the gastrula stage in the toad Bufo arenarum Hensel. Fertilization triggered a 30% and a 40% decrease in triacylglycerol and diacylglycerol, respectively. In contrast, free fatty acid increased continuously from oocyte to gastrula stage with an accumulation of palmitate predominating. However, the observed increase in free fatty acid was too small to account for the decreases in both neutral glycerides. The decrease in triacylglycerol might be a reflection of the activation of lipolytic enzymes and the subsequent oxidation of fatty acids to meet the increased metabolic energy requirements brought on by fertilization. The diminished diacylglycerol content due to fertilization may be accounted for, at least in part, by the utilization of diacylglycerol in the synthesis of membrane phospholipids, inasmuch as their decrease occurred simultaneously with an increase in phosphatidic acid. When cell-free homogenates taken from the three stages of development (unfertilized, fertilized and gastrula) were incubated in Tris-Ringer buffer for 90 min, free fatty acid accumulated. Triacylglycerol and diacylglycerol did not change substantially during this incubation period. This fact indicates that the free fatty acid released during incubation was not derived from neutral glycerides, but probably from membrane phospholipids. The release of free fatty acid was significantly greater in samples from the fertilized oocyte stage. The results described in this paper suggest that the synthesis of membrane phospholipids, including an enhanced turnover of the acyl moiety, plays a significant role in the metabolic events activated by fertilization.

Characterization of a Ca2+-stimulated lipid peroxidizing system in the sea urchin egg

Addition of calcium chloride to an egg homogenate of Strongylocentrotus purpuratus stimulates O2 consumption which is not inhibited by millimolar cyanide. Results strongly suggest that Ca2+-stimulated O2 consumption is at least partially the result of polyunsaturated fatty acid oxidation. First, addition of arachidonic acid (AA), or other polyunsaturated fatty acids, to the homogenate enhance Ca2+-stimulated O2 consumption; this enhancement, by AA, being coupled to its oxidation to a hydroxy fatty acid. Second, calcium stimulates a lipase activity in the homogenate that is capable of releasing free fatty acids. Third, Ca2+-stimulated O2 consumption and AA oxidation have virtually identical calcium requirements and pH optima. The sequence of events then is that upon calcium addition to the homogenate, lipase activity is increased which liberates free fatty acids. At the same time calcium also activates a polyunsaturated fatty acid oxygenase, possibly lipoxygenase, that converts the free fatty acids to hydroxy fatty acids. The possible physiological importance of this reaction is underscored by the high affinity for Ca2+ [approximately 10(-7)M], an ion known to increase above the required levels at fertilization. The pH activity profile also suggests possible physiological modulation because a pH change of 6.8 increasing to 7.2, as suggested to occur after fertilization, yields almost a twofold increase in O2 consumption. Egg homogenates from many other invertebrate species have the ability to oxidize AA in a Ca2+-dependent fashion. For the investigated species, the presence of Ca2+-stimulated O2 consumption and AA oxidation correlates with the presence of cyanide insensitive respiration in the intact egg.

Sperm surface proteins persist after fertilization

Certain sperm components labeled with fluorescein isothiocyanate or its radioactive derivative, 125I-diiodofluorescein isothiocyanate (125IFC), are transferred at fertilization to the egg, where they persist throughout early cleavage stages at a localized site in the embryo cytoplasm (Gabel, C. A., E. M. Eddy, and B. M. Shapiro, 1979, Cell, 18:207-215; Gundersen, G. G., C. A. Gabel, and B. M. Shapiro, 1982, Dev. Biol., 93:59-72). By using image intensification we have extended these observations in the sea urchin to the pluteus larval stage, in which greater than 60% of the embryos have localized fluorescent sperm components. Because of the unusual persistence of the sperm components in the embryo, a characterization of the nature of the labeled species in sea urchin sperm was undertaken. Approximately 10% of the 125IFC was in sperm polypeptides of Mr greater than 15,000. These proteins were on the sperm surface as shown by their sensitivity to externally added proteases. The remainder of the 125IFC in sperm was in several low-molecular-weight species, none of which was 125IFC-derivatized phospholipid. To determine if any labeled sperm polypeptides remained intact in the embryo after fertilization, 125IFC-labeled sperm proteins were recovered from one-cell and late gastrula stage embryos by using an anti-IFC immunoadsorbent. Most of the labeled sperm proteins were degraded shortly after fertilization; however, distinct sets of labeled polypeptides were recovered from both one-cell and gastrula stage embryos. Six of the labeled polypeptides recovered from both embryonic stages had identical SDS gel mobilities as labeled sperm polypeptides. Other polypeptides in the embryos appeared to arise from limited proteolysis of sperm proteins. Thus, in this physiological cell fusion system, individual sperm proteins are transferred to the egg at fertilization, and some persist intact or after specific, limited degradation long after gamete fusion, until at least the late gastrula stage.

Characterization of cortical secretory vesicles from the sea urchin egg

In order to evaluate the potential role of cortical vesicle exocytosis in modifying the egg surface at fertilization, we have begun characterization of the cortical secretory vesicle. Earlier reports (N. K. Detering, G. L. Decker, E. D. Schmell, and W. Lennarz, 1977, J. Cell Biol. 75, 899-914) have described the isolation of an egg cell surface complex which consists of the egg plasma membrane and cortical secretory vesicles. We have now developed a method of dissassembling the cell surface complex and isolating the cortical vesicles. The very low levels of contaminating plasma membrane in this preparation allow the meaningful comparison of plasma membrane and cortical vesicle proteins and lipids. The cortical vesicles were found to be rich in high-molecular-weight PAS-positive proteins. The majority of these glycoconjugates were solubilized by hypotonic lysis of the cortical vesicles and probably represent proteins sequestered inside the intact vesicles. The fatty acid composition of the cortical vesicles was found to be unusually high in arachidonic acid. The fatty acid composition of the cortical vesicles was closely similar to that of the plasma membrane; however, the cortical vesicles were substantially higher in cholesterol content.

Inhibition of polyisoprenoid and glycoprotein biosynthesis causes abnormal embryonic development

Compactin, a potent inhibitor of polyisoprenoid biosynthesis, induces abnormal gastrulation during sea urchin development at concentrations that have no effect on earlier embryonic development or on macromolecular synthesis. Three lines of evidence suggest that the developmental lesion caused by compactin results from inhibition of dolichol biosynthesis and a concomitant inhibition in the biosynthesis of the oligosaccharide chains of N-linked glycoproteins. (i) Embryos cultured in the presence of compactin gastrulate normally when supplemented with dolichol alone, whereas supplementation with cholesterol or coenzyme Q or both does not prevent the compactin-induced developmental lesion. (ii) Exogenously supplemented [3H]dolichol is incorporated into a compound with the chromatographic properties of oligosaccharide-pyrophosphoryldolichol. (iii) Embryos cultured in the presence of compactin exhibit a decreased capacity to synthesize mannose-labeled glycolipids and N-linked glycoproteins. This decrease in synthesis is abolished if the embryos are cultured in the presence of dolichol along with compactin.

Fatty acid composition of unfertilized and fertilized eggs of the sea urchin, Arbacia punctulata

Fatty acid compositions of polar lipids and triacylglycerols isolated from eggs of the sea urchin, Arbacia punctulata, were examined before and 15 min after insemination. The main fatty acids present in polar lipids and triacylglycerols were palmitate, palmitoleate, eicosaenoate, arachidonate and eicosapentaenoate, while palmitate and palmitoleate predominated in triacylglycerols. There were no significant changes in weight percentage of individual fatty acids of either polar lipids or triglycerides of eggs after insemination.