Biosynthesis, metabolism and biological role of furan fatty acids in fish will be studied. To this end, nutritional and radioactive precursor experiments will be carried out in vivo. Methods for chemical synthesis of furan fatty acids will be applied to obtain them in specifically labeled form. The correlation of fluctuating levels of furan fatty acids in liver and testis lipids with the reproductive cycle of fish will be studied by histological and EM methods. Further work will characterize the tissue of their biosynthesis and the enzyme processes involved.