抄録
1. Young guinea pigs fed on a choline-deficient diet supplemented with 0.117% MME showed as good growth and survival rate as those fed on a choline-supplemented diet (control). Addition of a larger amount of MME (0.328%) in the diet, however, resulted in a low growth rate and a high mortality.
2. In liver slices of MME-fed guinea pigs, much more methyl group of methionine-C3H3 was incorporated into phospholipids than in those of the control ones; one-third of radioactive methyl incorporated was found in phosphatidyl-DME and two-thirds in lecithin. The high values of incorporation and the distribution of radioactivity were not affected by preincubation with MME or DME.
3. Liver microsome of MME-fed guinea pigs showed a much higher incorporation of methyl group of S-adenosylmethionine-14CH3 into phospholipids than those of control or choline-deficient ones.
4. When the lipids extracted from livers of MME-fed guinea pigs (M-lipid) were added to the reaction system containing liver microsomes from control or choline-deficient animals, the incorporation of labeled methyl group from S-adenosylmethionine-14CH3 was markedly enhanced.
5. After addition of M-lipid, liver microsomes from choline-deficient guinea pigs incorporated twice as much methyl group of S-adenosylmethionine-14CH3 into phospholipids than those from control ones.
6. It was proved that guinea pig liver microsomes possessed enough activity to carry out the second and the third methylation step of lecithin synthesis from phosphatidylethanolamine, that this was increased in a choline-deficient state, and that a considerable amount of phosphatidyl-MME and -DME were deposited in the livers of MME-fed guinea pigs.
