STEROLS OF TETRASELMIS (PRASINOPHYCEAE)

1. Sterols were identified from 11 isolates of Tetraselmis, a unicellu lar Prasinophyte alp used frequently as food in mariculture. 2. The pr incipal sterol in eight isolates was either 24-methylenecholesterol or 24-methylcholesterol; the latter was determined to be campesterol in all cases. 3. Campesterol is the first 24alpha sterol to be reported i n the Prasinophyceae. 4. In the remaining three isolates, cholesterol was the principal sterol with smaller amounts of 24-methylenecholester ol and campesterol present; in two of these strains total sterol appro ached 3% of dry weight. 5. This is the first report of cholesterol as the principal sterol of a Prasinophyte; the C28 sterols found in Tetra selmis are the dominant sterols in most Prasinophyceae studied to date .