Changes in the Lipid Fraction of Eel Gills after Ionizing Irradiation in Vivo and a Shift from Fresh to Sea Water

Sixteen eels were adapted to tap water for a week. Then eight of them were irradiated with 1000 R γ-radiation and four of the irradiated group and four of the nonirradiated control group were transferred to sea water. The rest remained in tap water. Three days later all were incubated with 14 C-labeled acetate and 32 P-labeled phosphate added to the water in the aquariums. Lipids from the gills were separated by tlc and the individual fatty acids were assayed by paper chromatography. Results showed an enhanced incorporation of 14 C activity into sterol esters in sea water. This was further intensified by γ-irradiation. Similarly, γ-irradiation intensified a relatively enhanced incorporation in sea water of 32 P activity into lecithin, and there was a relatively increased synthesis of certain 14 C-labeled unsaturated fatty acids (mainly ${\rm C}_{16\colon 1}$) in the gills of animals that had both been irradiated and transferred to sea water. By measuring lipid biosynthesis in gill tissue it was thus possible to show an interaction between the effect of ionizing irradiation and the salinity of the environment, in agreement with previous biological findings.