The effect of an artificial diet on the biochemical composition of the gonads of the sea urchin (Strongylocentrotus droebachiensis)

Unusual polyunsaturated fatty acids in edible marine worms identified by covalent adduct chemical ionization mass spectrometry

Non-traditional seafood, such as spoon worms (Urechis unicinctus) and peanut worms (Sipunculus nudus), serves as both delicacies and potential solutions to the global food insecurity crisis. Despite being consumed primarily in parts of China, Korea, and Japan, the nutritional values especially the complex fatty acid compositions of these marine worms are difficult to characterize. To overcome this obstacle, we employed covalent adduct chemical ionization (CACI) tandem mass spectrometry for the de novo identification of their unusual polyunsaturated fatty acids (PUFA). Through this method, we identified several PUFA with polymethylene-interrupted (PMI) double bond configurations, including 22:3(7Z,13Z,16Z), a novel PUFA derived from sciadonic acid. U. unicinctus exhibits an exceptionally low n-6/n-3 PUFA ratio of 0.15, making it a potential functional food to counterbalance the n-6/n-3 imbalance in modern diets. S. nudus boasts notably high concentrations (∼3 %, wt/wt) of branched chain fatty acids (BCFA), exceeding typical levels found in dairy products.

Edible Sea urchins Echinus esculentus from Norwegian waters- Effect of season on nutritional quality and chemical contaminants

This study aimed to characterize Echinus esculentus gonads in terms of biometric parameters and nutritional quality at two sites in Mid-Norway at four different seasons. The chemical contamination of the gonads was also investigated for the first time through the evaluation of 28 macro- and trace elements and 32 components from the emerging and persistent group per- and polyfluoroalkyl substances (PFAS). The spawning period was determined in summer, given that the gonad index was the lowest in this season for both sites. Protein concentrations were constant (8%-10%). However, lipid contents (1%-3%) were noticed to be higher in gonads during autumn and winter. The gonads had high contents of PUFA mainly EPA and DHA, followed by SFA, and MUFA year around for both locations. E. esculentus gonads constitute a good source of fatty acids, macro, and trace elements. This species could also be a bioindicator for the monitoring of marine environments.

Observations from the Hydrolysis of the Green Sea Urchin (Strongylocentrotus droebachiensis)

There is a large amount of coproduct generated by the sea urchin fisheries around the world as well as a growing interest in removing large quantities of undersize and low value sea urchins from barren areas in the northern Atlantic and Pacific coasts as well as other areas around the world. The authors believe there is scope to develop a hydrolysate product from this and this study gives preliminary observations on the characteristics of hydrolysate from the sea urchin Strongylocentrotus droebachiensis. The biochemical composition for S. droebachiensis is moisture 64.1%, protein 3.4%, oil 0.9%, and ash 29.8%. Amino acid composition, molecular weight distribution, lipid-class, and fatty acid composition are also presented. The authors suggest a sensory-panel mapping be undertaken on future sea urchin hydrolysates. Possible uses for the hydrolysate are unclear at this stage but the combination of amino acids and the relatively high levels of glycine, aspartic acid, and glutamic acid should be further investigated.

Unusual polymethylene-interrupted, Δ5 monounsaturated and omega-3 fatty acids in sea urchin (Arbacia punctulata) from the Gulf of Mexico identified by solvent mediated covalent adduct chemical ionization mass spectrometry

Sea urchin (class Echinoidea) gonads are a prized delicacy in Japan and many other world cultures. The complexity of its fatty acid (FA) profile, particularly minor FA, presents a formidable analytical challenge. We applied solvent mediated (SM) covalent adduct chemical ionization (CACI) tandem mass spectrometry to comprehensive de novo structural and quantitative characterization of the FA profile of Gulf of Mexico Atlantic sea urchin (Arbacia punctulata). >100 FA were detected including many with unusual double bond structure. Gulf sea urchin gonad lipids are rich in Δ5 monounsaturated FA 20:1(5Z) at 2.7% and the polymethylene-interrupted (PMI) diene 20:2(5Z,11Z) at 4.9%, as well as common omega-3 eicosapentaenoic acid (EPA; 5Z, 8Z, 11Z, 14Z, 17Z) at 9.8%±3.1% and arachidonic acid (AA; 5Z, 8Z, 11Z, 14Z) at 6.1%±2.1%. We propose plausible desaturation/elongation-based biochemical pathways for the endogenous production of unusual unsaturates. Unusual unsaturates may modify mammalian signaling and present novel bioactivities.

Comparative lipidomics profiling of the sea urchin, Strongylocentrotus intermedius

Strongylocentrotus intermedius is an edible sea urchin and well-known for its nutritional value, such as a high content of polyunsaturated fatty acids (PUFAs). We carried out an untargeted lipidomics via high-resolution ultra-high-performance liquid chromatography - mass spectrometry (UPLC-MS) to highlight the features of the lipids profile of sea urchin gonad, which allowed for a more detailed interpretation of the accumulation of PUFAs with different abundances among sea urchins. For the first time, lipidomics profiling of lipid abundances in S. intermedius was demonstrated. We detected 11 PUFAs in sea urchin gonads, which represented >54.13% of the total fatty acid content. A total of 1552 lipid molecular species belonging to 36 lipid classes were identified. Lipidomics profiles data were analyzed using orthogonal partial least squares discriminant analysis (OPLS-DA) model and distinguished the PUFA abundances in both sexes of sea urchins. The significant differences in lipid molecules were highlighted and the major lipid classes identified were phosphatidylcholine (PC [19 species]) among females and triglycerides (TG [11 species]) among males. PC (42: 11) may be used as a potential marker for distinguishing high levels of PUFAs in sea urchin individuals, which as the result of the high level of PC (42:11). These data enrich the lipid profile library of aquatic products and provide a more reliable and refined biomarkers for the further research on fatty acid synthesis and metabolism in aquatic animals.

Characterization of the lipid fraction of wild sea urchin from the Sardinian Sea (western Mediterranean)

The fatty acid (FA) composition of Spatangus purpureus, Echinus melo, Sphaerechinus granularis, and Paracentrotus lividus, sea urchins, has been studied. Sea urchins were collected at different depth along Sardinia coast in the Mediterranean sea, and their gonad was measured, separated, and analyzed for FA composition by gas chromatography-mass spectrometry. A total of 53 FAs were detected, 16 saturated (SFA), 10 monounsaturated (MUFA), 9 polyunsaturated (PUFA), and 13 highly unsaturated (HUFA). Moreover, 5 furan FAs (FFAs) were revealed for the first time in sea urchin. The HUFA and PUFA classes were the most represented accounting for almost 80% of total FAs. Among these compounds, C20:4 n6 (19.64, 20.52, 23.37, and 8.48 mg/g, respectively) and C22:6 n3 (19.68, 20.05, 3.83, and 1.78 mg/g, respectively) were the most abundant. The results of principal component analysis indicated that the sea urchin samples could be clearly discriminated with respect to their FAs composition.

Effect of diets supplemented with different sources of astaxanthin on the gonad of the sea urchin Anthocidaris crassispina

The effect of the microalgae Haematococcus pluvialis and Chorella zofingiensis, and synthetic astaxanthin on the gonad of the sea urchin Anthocidaris crassispina was studied. The basal diet was supplemented with H. pluvialis, C. zofingiensis, or synthetic astaxanthin, at two levels of astaxanthin (approximately 400 mg/kg and 100 mg/kg), to obtain the experimental diets HP1, HP2, CZ1, CZ2, AST1, and AST2, respectively, for two months of feeding experiment. The results showed that the concentrations of astaxanthin in the gonads of the sea urchins fed these experimental diets ranged from 0.15 to 3.01 mg/kg dry gonad weight. The higher astaxanthin levels (>2.90 mg/kg) were found in the gonads of the sea urchins fed the diets HP1 (containing 380 mg/kg of astaxanthins, mostly mono- and diesters) and AST1 (containing 385 mg/kg of synthetic astaxanthin). The lowest astaxanthin level (0.15 mg/kg) was detected in the gonads of the sea urchins fed the diet CZ2 (containing 98 mg/kg of astaxanthins, mostly diesters). Furthermore, the highest canthaxanthin level (7.48 mg/kg) was found in the gonads of the sea urchins fed the diet CZ1 (containing 387 mg/kg of astaxanthins and 142 mg/kg of canthaxanthin), suggesting that astaxanthins, especially astaxanthin esters, might not be assimilated as easily as canthaxanthin by the sea urchins. Our results show that sea urchins fed diets containing astaxanthin pigments show higher incorporation of these known antioxidant constituents, with the resultant seafood products therefore being of potential higher nutritive value.

The influence of season on the gonad index and biochemical composition of the sea urchin Paracentrotus lividus from the Golf of Tunis

Seasonal variation in the gonad weight and biochemical composition of the sea urchin Paracentrotus lividus from the Golf of Tunis (Tunisia) were studied between September 2003 and August 2004. The highest gonad indices occurred in March (16.71%). The spawning period occurred between April and July and resulted in a fall in gonad indices to low level (7.12 ± 0.12%). Protein constituted the main component of the gonad, and lipid and carbohydrate were found at appreciable amounts. Consistent with the gonad cycle, sea urchin biochemical components showed clear seasonal variation with a significant decrease during the spawning period. The polyunsaturated fatty acid (PUFA) group was found at high level (40% of the total fatty acids). Of the PUFA group, eicosapentaenoic (C20:5 n − 3) and eicosatetraenoic (C20:4 n − 3) were the most abundant gonadal lipids. The level of PUFA was significantly affected by temperature variation showing an increase during the cold months and a decrease in the hot months.

Trophic ecology of the sea urchin Spatangus purpureus elucidated from gonad fatty acids composition analysis

Irregular sea urchins such as the spatangoid Spatangus purpureus are important bioturbators that contribute to natural biogenic disturbance and the functioning of biogeochemical cycles in soft sediments. In the coastal waters of the Balearic Islands S. purpureus occurs in soft red algal beds, and can reach high densities. The diet of S. purpureus is unknown and it is particularly difficult to analyze the stomach contents of this group; therefore, we analyzed the fatty acid (FA) composition of the gonads and potential food resources in order to assess the trophic relationships of this species. The FA profiles of the gonads of S. purpureus agree well with the FA composition of the potential trophic resources (algae and sediment) and reveals changes between localities with different available resources. Three polyunsaturated FAs mainly contributes in the composition in the S. purpureus gonads: eicosapentaenoic acid (C20:5n-3) and arachidonic acid (C20:4n-6), both abundant in the macroalgal material, and palmitoleic acid (C16:1n-7), which is characteristic of sediment samples. Trophic markers of bacterial input and carnivorous feeding were significantly more abundant in sea urchins caught on bottoms with less vegetation. The current study demonstrates that the FA content of S. purpureus gonads is a useful marker of diet, as differences in the profiles reflected the variations in detritus composition. The results of this study show that this species has omnivorous feeding behavior; however, viewed in conjunction with available abundance data the results suggest that phytodetritus found within algal beds is an important carbon source for this species.

Changes in fatty acid composition of Mytilus galloprovincialis (Lmk) fed on microalgal and wheat germ diets

Dietary fatty acid incorporation and changes in various lipid and phospholipid classes in the mussel Mytilus galloprovincialis subjected to three different dietary regimens were analysed and compared. Group A was unfed; group B received a diet consisting of 100% Thalassiosira weissflogii, exhibiting the typical fatty acid composition of diatoms, and group C received a diet consisting of 100% wheat germ conferring a 18:2:n-6 abundance. Biochemical analyses of diets and mussels were carried out at the beginning and at the end of the 30-day experimental period. Starvation and T. weissflogii based diet poorly affected mussel growth and fatty acid composition which remained unchanged. On the contrary, the wheat germ-based diet increased the condition index and deeply affected the fatty acid profile of all lipid and phospholipid classes. The high dietary 18:2n-6 level drastically reduced tissue content of 20:4n-6, 20:5n-3 and 22:6n-3. The biosynthesis of Non Methylene Interrupted (NMI) dienoic fatty acid appeared to be insensitive to the high input of 16:1n-7 and 18:1n-9 respectively from diet B and C, and to the PUFA shortage of diet C. Nevertheless the two NMI trienoic derivatives, 20:3Delta5,11,14 and 22:3Delta7,13 16, were found higher in C with respect to other groups, presumably due to the high 18:2n-6 content of this diet.

Echinoderms: their culture and bioactive compounds

Of the five extant classes of echinoderms, it is the sea urchins (Echinoidea) and the sea cucumbers (Holothuroidea) that are both commercially fished and heavily overexploited. In sea urchins, it is the gonad of both males and females, normally referred to as'roe', that is a sought-after food. In the sea cucumber, the principal product is the boiled and dried body-wall or 'bêche-de-mer' for which there is an increasing demand. Many sea urchin and sea cucumber fisheries still have no management system or restrictions in place, and for those that do, the prognosis for catches to continue even at a reduced level is poor. Cultivation of these species increasingly becomes a necessity, both for stock enhancement programs and as a means to meet market demand. Sea urchin culture has been practised on a large scale in Japan for many decades, and effective methods for the culture and reseeding of species in these waters have been long established. Juvenile urchins are produced in their millions in state-sponsored hatcheries, for release to managed areas of seafloor. Outside of Japan, sea urchin cultivation is still a fairly recent practice, less than 10 years old, and largely still at a research level, although a range of species are now being produced in a variety of different culture systems. It is essential that the culture systems are adapted to be species-specific and meet with local environmental constraints. Sea cucumber cultivation originated in Japan in the 1930s and is now well established there and in China. Methods for mass cultivation of the tropical Holothuria scabra are now well established and practised in India, Australia, Indonesia, the Maldives and the Solomon Islands, with the focus of the research effort for both temperate and tropical species being centred on the production of juveniles in hatcheries for the restoration and enhancement of wild stocks. Like many other marine organisms, echinoderms have been, and continue to be, examined as a source of biologically active compounds with biomedical applications. Sea cucumber has been valued in Chinese medicine for hundreds of years as a cure for a wide variety of ailments. Some more recently isolated compounds, mainly from sea cucumbers and starfish, and including those with antitumour, antiviral, anticoagulant and antimicrobial activity are summarised below. When wild stocks decline, the demand created in the market place raises to the price of the product and, consequently, culturing is more likely to become viable economically. As this review shows, there have been dramatic advances in the culture methods of sea urchins and sea cucumbers in the last 10-15 years, to the extent that one can conclude that currently the major obstacles to successful cultivation are indeed economic rather than biological. Hence the future of the echinoculture industry is closely linked to that of the fisheries, whose fate will ultimately determine the market forces that will shape this growing industry.