The lipid content of Hymenolepis diminuta and Hymenolepis citelli

The lipids of prepatent 14-day-old Hymenolepis diminuta and Hymenolepis citelli were compared by chromatographic and colorimetric methods. The tapeworms were reared under carefully controlled conditions in which host diet, sex, and age as well as worm age and worm density were maintained constant. Hymenolepis diminuta had a mean lipid content of 5.2% of the fresh worm weight and 21.2% of the dry weight, whereas the values for H. citelli were 3.9% and 16.1%, respectively. Neutral lipid made up approximately 75% of the lipid of both worms and was composed of about 70–75% fatty acids, 15–20% unsaponifiables, and 10% glycerol. The phospholipid fractions were composed of phosphatidyl serine, phosphatidyl ethanolamine, phosphatidyl choline, plasmalogen, inositol phosphatide, and two other fractions, tentatively identified as cardiolipin and cerebroside. No qualitative differences could be detected between the lipids of the two worms, but they could be distinguished from each other quantitatively, especially in the phospholipid fatty acids. The major fatty acids of both tapeworms were myristic, palmitoleic, palmitic, gamma linolenic, linoleic, oleic, stearic, eicosapentaenoic, arachidonic, and arachidic acids. The 16-carbon acids constituted about 13% of the total fatty acids, while 18-carbon acids made up more than 75% of the total fatty acids, and no fatty acid had a chain length greater than 20 carbons.