Methionine Synthesis in Lemna

Methionine methyl group metabolism in lemna.

To provide information upon the ways in which Lemna paucicostata uses the methyl group of methionine, plants were grown for various periods (from 1 minute to 6.8 days) in the presence of a tracer dose of radioactive methyl-labeled methionine. Protein methionine accounted for approximately 19% of the accumulated methyl moieties; other methylated products, about 81%. The latter group included (pe...

Adaptation of Lemna paucicostata to Sublethal Methionine Deprivation.

During initial exposure to 40 nanomolar propargylglycine (PAG), Lemna paucicostata colonies undergo abnormal fragmentation and a lag in frond emergence, most severe at 24 to 48 hours. Thereafter, frond emergence resumes and the frond/colony ratio rises. Such ;adapted' plants withstand subculture into the same concentration of PAG without fragmentation or decreases in frond emergence, and displa...

Methionine synthesis in Neurospora crassa.

Horowitz and co-workers (Horowitz, 1947; Teas, Horowitz & Fling, 1948; Fling & Horowitz, 1951) have determined the pathway of methionine synthesis in Neurospora crassa, from genetic analysis of methionine-requiring mutant strains; it involves conversion of cysteine, via cystathionine, into homocysteine, which is methylated to methionine. A similar scheme has been suggested for methionine synthe...

Methionine synthesis in Ochromonas malhamensis.

Synthesis of methylated ethanolamine moieties: regulation by choline in lemna.

The results of experiments in which intact plants of Lemna paucicostata were labeled with either l-[(3)H(3)C]methionine, l-[(14)CH(3)]methionine, or [1,2-(14)C]ethanolamine support the conclusion that growth in concentrations of choline of 3.0 micromolar or above brings about marked decreases in the rate of biosynthesis of methylated forms of ethanolamine (normally present chiefly as phosphatid...