Abstract
Lipids in various tissues of the carp, Cyprinus carpio were analyzed. The fates of force-fed [1-14C] palmitic acids, [1-14C] cetyl alcohol, and oleyl [1-14C] linoleate, were compared with those given in vitro experiments. Major lipid classes in all except adipose tissue were found to be polar lipids (phospholipids) and triacylglycerols. The major fatty acids in nearly all the tissues were 16 : 0, 18 : 1, 18 : 2, and 22 : 6.
Although the radioactivity incorporation into wax esters from [1-14C] palmitic acid and [1-14C] cetyl alcohol for various tissue homogenates was quite high, in vivo incorporation of these labelled compounds into wax esters was very low and radioactivity was distributed mainly in the lipids of muscle, skin, hepatopancreas, intestine, and gill. Almost all the radioactivity in various tissues was present in phospatidylcholine and triacylglycerols. Most of the oleyl [1-14C] linoleate was easily hydrolyzed by various tissue homogenates. Force-fed oleyl [1-14C] linoleate was hydrolyzed in the intestine and then transported to other tissues, such as muscle, kin, gill, and hepatopancreas. Moreover, released radioactivity from oleyl [1-14C] linoleate was present in mainly phosphatidylcholine and triacylglycerols. Radioactivity was also detected in wax esters in plasma. Certain amounts for fatty acids released from [1-14C] triolein in the hepatopancreas homogenates were incorporated into wax esters; this was stimulated by the addition of oleyl alcohol. The present results indicate extensive hydrolysis of wax ester to possibly occur in the intestine and certain portions of the fatty alcohol moiety to be reesterifiied. The portions may be oxidized to fatty acids and which subsequently behave as dietary fatty acids.
