No abstract

Molecular dynamics simulations, using the collision dynamics method, were carried out for hydrated bilayers of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (18:0/18:1 9cis PC, SOPC͒ and 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphatidylcholine (18:0/22:6 3cis PC, SDPC͒. The simulation cells of the two bilayers consisted of 96 SOPC ͑or SDPC͒ molecules and 2304 water molecules: 48 lipid molecules per layer and 24 H 2 O molecules per lipid. The water was modeled by explicit TIP3P water molecules. The CuH bond-order-parameter ϪS CH profiles of the hydrocarbon tails, the bond orientation distribution functions and the root-mean-square values of the positional fluctuations of the lipid chain carbons were calculated. Simulation results are compared to the available experimental data and to other computer investigations of these lipid molecules. Several results of molecular-level self-consistent field calculations of these bilayers are also presented. Both theoretical methods reveal the same main characteristic features of the order-parameter profiles for the given bilayers. Some aspects of the physical properties of unsaturated lipids and their biological significance are discussed.

A comparative study of the lipid status (i.e., the total lipid and phospholipid concentrations and the percentage of fatty acids of the total lipids) of adult specimens of daubed shanny (Leptoclinus maculatus) from Svalbard waters (Isfjord) and slender eel blenny (Lumpenus fabricii) from the White Sea (Onega Bay and Tersky shore) was performed to study the metabolism and functions of lipids of these fishes in ontogeny and under various ecological conditions. Slender eel blenny from both areas of the White Sea were distinguished by a high level of sphingomyelin compared with the daubed shanny from Svalbard, and the amount of total phospholipids was higher in slender eel blenny from Onega Bay than in slender eel blenny from the Tersky shore. The extent of saturation and the signature of polyenic fatty acids varied according to the specific species of the Stichaeidae family under study. These results demonstrate the differences in the trophoecological and hydrobiological conditions of habitations of these species and highlighted the importance of considering certain trends in the lipid profiles of these fishes as specific features of the organization of the ecological and biochemical mechanisms of adaptation.

No abstract