Leishmania majorsynthesizes polyunsaturated fatty acids by using D6,D5 andD4 front-end desaturases, which have recently been characterized [Tri-podi KE, Buttigliero LV, Altabe SG & Uttaro AD (2006)FEBS J273, 271– 280], and two predicted elongases specific for C18D6 and C20D5 poly-unsaturated fatty acids, respectively.