BIOLOGIYA MORYA, 2013, Vol. 39, No. 2, pp. 136-143 |
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Phase transitions of phospholipids as a criterion for assessing the capacity for thermal adaptation in fish Far Eastern Federal University, Vladivostok 690091 E-mail: This study examines the crystal-liquid crystal phase transitions of the major phospholipids (PL), phosphatidylcholine (PC) and phosphatidylethanolamine (PE), from muscle tissue of marine fish living at a temperature of 0-4.1°C (Pacific cod Gadus macrocephalus, banded Irish lord Hemilepidotus gilberti, Atlantic halibut Hippoglossus hippoglossus, black edged sculpin Gymnocanthus herzensteini, dark colored flounder Pleuronectes obscurus, and plain sculpin Myoxocephalus jaok), as well as of fish living at 14 and 18°C (Far-eastern dace Tribolodon brandti). The PC and PE phase transition thermograms of all investigated species displayed specific profiles. The largest share of the thermogram area at temperatures higher than those of habitat was found for PC (28-40%) and PE (47-82%) of black edged sculpin, dark colored flounder, and plain sculpin, which are characterized by reduced physiological activity at low temperatures. In Pacific cod, banded Irish lord, halibut, and Far-eastern dace, this parameter was much lower, 0-18% (PC) and 0-39% (PE). The thermotropic behavior of PC and PE was symbathic in all fish, except cod and plain sculpin. The transition enthalpy of PC in all investigated species was 2.8 times higher than that of PE. To interprete the varied PC and PE thermogram profiles of fish with similar fatty acid composition, the data on the composition of molecular species of these PL appeared to be most informative. This study suggests that each fish species has its own strategy of thermal adaptation, which is realized through a certain set of PL molecular species. Key words: phospholipids, fatty acids, phosphatidylcholine, phosphatidylethanolamine, molecular species, marine fish, thermal adaptation, crystal-liquid crystal phase transitions. |
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