Mammalian cells can metabolize linoleic acid (C,8:2, , , , , ) by A-6-desaturation to y-linoleic acid (C18:3,,,-,,), which can be elongated to dihomo-y-linoleic acid (C211.3,,z, ), and subsequently undergo A-5-desaturation to arachidonic acid (AA) (C211:J,rr-,,) 11 I . Most freshwater fish are also capable o f this process 121, whereas marine species such as turbot (Scopthulmirs maximus) appare...