AGE-RELATED-CHANGES IN NEUTRAL LIPID-CONTENT OF PARAMECIUM-PRIMAURELIA AS REVEALED BY NILE RED

Cellular neutral lipid content of Paramecium primaurelia was measured during culture and clonal life using nile red (9-diethylamino-5H-benzo [alpha]phenoxazine-5-one), a dye utilized for lipid analysis in both m ammalian cells and in ciliated protozoa. Lipid droplets in P. primaure lia are concentrated in the anterior pole of the cell; their number is maximum in early log phase cells and decreases in late log phase cell s. The quantitative determination of neutral lipids was obtained measu ring the fluorescence from the excitation and emission spectra of 480 nm and 540 nm, respectively. Neutral lipid content decreases linearly during the log phase of growth while the decline is minimum during the stationary phase. In the late log phase, the amount is 30% of that of the early log-phase cells. Though the cell size declines too, cell ar ea and lipid content decreases are not correlated in the middle log ph ase, because the maximum lipid reduction is obtained when the cell siz e is relatively constant. The cellular lipid content also changes duri ng the clonal life. Neutral lipids decrease discontinuously (r = -0.75 , P < 0.05) as the fission age increases. No relationship was found be tween lipid content and food vacuole formation during both culture and clonal life.