UPTAKE AND METABOLISM OF LIPOSOMES BY ARTEMIA-NAUPLII

Newly hatched Artemia nauplii were fed four types of liposomes for 48 h. Labeled liposomes were prepared with dipalmitoyl-[2-palmitoyl-1-C-1 4] phosphatidylcholine (C-14-PC) or [1-C-14]glycine (C-14-glycine). No n-labeled liposomes contained dietary protein, glucose, vitamins and m inerals or physiological saline. Unfed nauplii served as the control. After 24 and 48 h of feeding, total lipids were extracted with chlorof orm and methanol. Solvent insoluble residues were hydrolysed with 1 N NaOH. Methanol and chloroform fractions and NaOH hydrolysates were mea sured for radioactivity. Approximately 15% of C-14-glycine and C-14-PC was detected in the nauplii after 24 h. Nearly 80% of the total incor porated C-14-glycine was recovered in the NaOH hydrolysate of the naup lii, while 85% of the total incorporated C-14-PC radioactivity was fou nd in the chloroform fraction. The methanol fraction, on the other han d, contained 17% of the total incorporated C-14-glycine after 24 h. Th e total lipid content of the nauplii fed non-labeled liposomes contain ing dietary compounds or physiological saline was significantly higher than that of the unfed nauplii at 24 h. There were no remarkable diff erences in the fatty acid compositions of the nauplii among treatments due to the similarities in the fatty acid compositions of liposomes a nd nauplii. Arachidonic (20:4n-6) and eicosapentaenoic (20:5n-3) acid content of the nauplii fed non-labeled liposomes containing dietary ma terial were higher than the unfed nauplii after 48 h. The results of t his study suggest that liposomes may be used to enrich Artemia nauplii with phospholipids and free amino acids.