The samples of soft coral Sinularia flexibilis were collected from January to December in one year from Nha Trang, Khanh Hoa coastal. Initial assessment the month-by-month fluctuation of total lipid content and lipid classes composition in this species was conducted. Total lipid content reached the highest value during March to May, lower in the period of June-September and bottomed in October and November. There was a significant decrease in this content between May and June; September and October; the content increase from February to March but not stable during October to February. The lipid classes composition of Sinularia flexibilis includes polar lipids (PL), sterols (ST); triacylglycerol (TAG), monoalkyldiacyl-glycerol (MADAG), wax (W) and free fatty acids (FFA). The concentration of PL in summer (April-August) was lower than that in winter (September-February), this content increased significantly during November-December meanwhile it was observed to decrease in April-May, December-January. The content of ST increased from October to March and declined from April to September. The remain classes including W, MADAG, TAG tend to increase in the summer period and decline in the other months. The fluctuation of lipid classes composition throughout the year is closely related to the presence of zooxanthellae microalgae in corals at different times of the year and is directly influenced by environmental conditions, especially sea water temperature. In addition, the effect of maturation and reproduction of this coral with the increase or release of reproductive materials also observed.

We conduct a study to investigate the year-round fluctuation of lipid composition and content in Pacific oysters (Crassostrea gigas) cultured in Van Don, Quang Ninh, for the first time. Our results showed that the total lipid content of oysters ranged from 1% to 1.6%, with the highest levels observed during their pre-reproductive period (July and December). Polyunsaturated fatty acids were the most abundant type of lipids in oysters, ranging from 41.66% to 53.36%. We identified six lipid classes in Pacific oysters, with the three dominant classes being PoL, ST, and TG, which exhibited significant variation, with the highest variability observed in May and June and the lowest in July. The primary fatty acids in oyster lipids were 14:0, 16:0, 18:0, 18:1n-7, 20:4n-6, 20:5n-3, and 22:6n-3. In summary, our study provides novel insights into the lipid composition and content of Pacific oysters cultured in Van Don, Quang Ninh.The results demonstrate the temporal variability in lipid classes and fatty acid composition throughout the year, with the highest lipid content observed during the pre-reproductive period. These findings could contribute to better understanding the nutritional value of Pacific oysters and inform future aquaculture practices.

In this report, by a high performance liquid chromatography (HPLC) - high resolution mass spectrometry (HRMS) method, 7 molecular species of phospholipid in the polar lipid class were identified including phosphatidylinositol (PI) and phosphatidylglycerol (PG). The PI 32:0 (16:0/16:0) and PG 34:3 (16:1/18:2) molecular species have the highest content. PI molecular species are mainly formed by saturated fatty acids (16:0, 18:0) and only one polyunsaturated fatty acids C20:4, while PG species are formed by unsaturated fatty acids (16:1, 18:2 and 18:3) and only one saturated fatty acid C16:0.

No abstract