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.

Copper and ocean acidification interact to lower maternal investment, but have little effect on adult physiology of the Sydney rock oyster Saccostrea glomerata

It remains unknown how molluscs will respond to oceans which are increasingly predicted to be warmer, more acidic, and heavily polluted. Ocean acidification and trace metals will likely interact to increase the energy demands of marine organisms, especially oysters. This study tested the interactive effect of exposure to elevated pCO₂ and copper on the energetic demands of the Sydney rock oyster (Saccostrea glomerata) during reproductive conditioning and determined whether there were any positive or negative effects on their offspring. Oysters were exposed to elevated pCO₂ (1000 μatm) and elevated copper (Cu 50 μg L^-1 [0.787 μM]) in an orthogonal design for eight weeks during reproductive conditioning. After eight weeks, energetic demands on oysters were measured including standard metabolic rate (SMR), nitrogen excretion, molar oxygen to nitrogen (O:N) ratio, and pH_e of adult oysters as well as the size and total lipid content of their eggs. To determine egg viability, the gametes were collected and fertilised from adult oysters, the percentage of embryos that had reached the trochophore stage after 24 h was recorded. Elevated pCO₂ caused a lower extracellular pH and there was a greater O:N ratio in adult oysters exposed to copper. While the two stressors did not interact to cause significant effects on adult physiology, they did interact to reduce the size and lipid content of eggs indicating that energy demand on adult oysters was greater when both elevated pCO₂ and copper were combined. Despite the lower energy, there were no negative effects on early embryonic development. In conclusion, elevated pCO₂ can interact with metals and cause greater energetic demands on oysters; in response oysters may lower maternal investment to offspring.

The role of fatty acids and triglycerides in the gonads of Paracentrotus lividus from Sardinia: Growth, reproduction and cold acclimatization

A detailed characterization of lipid extracts from gonads of P. lividus over a year has been performed combining GC and NMR measurements. For this purpose, sea urchins from two different Sardinian coastal areas were collected monthly. The results underlined a correlation between gonad fatty acids profiles and both water temperature and reproduction process. In particular, EPA and ARA appear to be the most altered fatty acids following seasonal changes. It is suggested that EPA could represent a biomarker of reproduction, reaching a content around 14% during gametogenesis, mainly due to an increase of the sn-1,3 position in TAGs. On the contrary, ARA seems to play a more important role in response to cold acclimatization, which is reflected in a modulation of ARA content in the sn-1,3 position in TAGs.

Development under elevated pCO2 conditions does not affect lipid utilization and protein content in early life-history stages of the purple sea urchin, Strongylocentrotus purpuratus

Ocean acidification (OA) is expected to have a major impact on marine species, particularly during early life-history stages. These effects appear to be species-specific and may include reduced survival, altered morphology, and depressed metabolism. However, less information is available regarding the bioenergetics of development under elevated CO(2) conditions. We examined the biochemical and morphological responses of Strongylocentrotus purpuratus during early development under ecologically relevant levels of pCO(2) (365, 1030, and 1450 μatm) that may occur during intense upwelling events. The principal findings of this study were (1) lipid utilization rates and protein content in S. purpuratus did not vary with pCO(2); (2) larval growth was reduced at elevated pCO(2) despite similar rates of energy utilization; and (3) relationships between egg phospholipid content and larval length were found under control but not high pCO(2) conditions. These results suggest that this species may either prioritize endogenous energy toward development and physiological function at the expense of growth, or that reduced larval length may be strictly due to higher costs of growth under OA conditions. This study highlights the need to further expand our knowledge of the physiological mechanisms involved in OA response in order to better understand how present populations may respond to global environmental change.