| Abstract: | The phospholipid composition from various organs of the fresh water eel, such as gill, kidney, gut, liver and muscle, were determined by thin-layer chromatography. The major phosphatides found in these tissues were PC, PE and SPH and minor constituents PS, PI, DPG, AP and also LPC in the gut. A greater percentage of PS and SPH occurs in the osmoregulatory effector organs such as gill, kidney, and gut. From in vivo comparative kinetic studies of the 32P incorporation into the phospholipids, between 6 and 48 hours, certain remarkable features of phospholipid metabolism have been found in these tissues. A low uptake of inorganic 32P into the tissue lipid phosphorus was observed in the eel at 15 degrees C. The specific activity of the lipid phosphorus increased continuously in all tissues during 48 hours after 32P injection. During this experimental period, phosphatidic acid and phosphatidyl inositol fractions were labelled most rapidly in gill, kidney and gut, while the specific activity of the phosphatidyl choline fraction remained low in these organs. In liver, the rate of PC formation appears to be faster than the PI and PE biosynthesis. In gill and gut, the PE showed greater turnover than the PC as measured by 32P incorporation. In the eel, an euryhalin fish, the DPG of osmoregulatory effector organs has a high specific activity at all times. PS showed only a high specific activity in the gill. Labelling of SPH occured slowly in the various tissues only becoming evident after 24 hours. The results are compared with those published for other poikilotherm and homeotherm vertebrates. Relative differences between the turnover of various tissue phosphatides are discussed with of reference to the general scheme on phospholipid biosynthesis and to the physiological functions of the various organs. |
