K. B. Chatson

13C nuclear magnetic resonance detection of interactions of serine hydroxymethyltransferase with C1-tetrahydrofolate synthase and glycine decarboxylase complex activities in Arabidopsis.

In C3 plants, serine synthesis is associated with photorespiratory glycine metabolism involving the tetrahydrofolate (THF)-dependent activities of the glycine decarboxylase complex (GDC) and serine hydroxymethyl transferase (SHMT). Alternatively, THF-dependent serine synthesis can occur via the C1-THF synthase/SHMT pathway. We used 13C nuclear magnetic resonance to examine serine biosynthesis by these two pathways in Arabidopsis thaliana (L.) Heynh. Columbia wild type. We confirmed the tight coupling of the GDC/SHMT system and observed directly in a higher plant the flux of formate through the C1-THF synthase/SHMT system. The accumulation of 13C-enriched serine over 24 h from the GDC/SHMT activities was 4-fold greater than that from C1-THF synthase/SHMT activities. Our experiments strongly suggest that the two pathways operate independently in Arabidopsis. Plants exposed to methotrexate and sulfanilamide, powerful inhibitors of THF biosynthesis, reduced serine synthesis by both pathways. The results suggest that continuous supply of THF is essential to maintain high rates of serine metabolism. Nuclear magnetic resonance is a powerful tool for the examination of THF-mediated metabolism in its natural cellular environment.

Partial synchrony in soybean cell suspension cultures induced by ethylene.

Abstract Partial synchrony of cell division in continuous cultures of soybean cell suspensions was obtained by flushing the cultures with ethylene at intervals of 36 h. The most pronounced synchrony resulted from flushing the suspensions with 3% ethylene for 3 h, followed immediately by 3% CO 2 for 3 h and 30 h aeration prior to the next ethylene treatment. Soybean cells responded to this regime of gassing also with a significant enhancement of growth.

Alkaloid production in Catharanthus roseus cell cultures: Initial studies on cell lines and their alkaloid content☆

Abstract Several hundred serially cultured cell suspensions derived from three cultivars of periwinkle ( Catharanthus roseus ) were established in Gamborgs B 5 medium and then transferred to Zenks alkaloid production medium. Total alkaloid concentration ranged from 0.1 to 1.5% of dry weight. Alkaloids present were of the corynanthe, strychnos and aspidosperma types, with the greatest diversity arising during the third to the fifth week of subculturing. The alkaloid content appeared both specific for, and reproducible in, individual cell lines.

Alkaloid production in Catharanthus roseus (L.) G. Don. : VI. Variation in alkaloid spectra of cell lines derived from one single leaf.

Analysis of 76 cell clones derived from one leaf of a periwinkle plant (Catharanthus roseus (L.) G. Don) showed the occurrence of Corynanthe-, Strychnos-, and Aspidosperma-type alkaloids. The majority of clones (62%) displayed compounds of all three types. Variation of the alkaloid spectra of the cell clones was low when compared to that found previously with serially subcultured callus and cell suspensions derived from different plants.

Studies in plant tissue culture. The synthesis and biosynthesis of indole alkaloids

Abstract Studies involving plant tissue cultures of Catharanthus roseus are described. Investigations concerning the propagation of cell lines of this plant for the purposes of producing indole alkaloids within the Corynanthe, Aspidosperma and Iboga families are presented. The utilization of such tissue culture systems for studies in biosyntheses and isolation of enzymes are also discussed.

Alkaloid production in Catharanthus roseus (L.) G. Don cell cultures. XIII. Effects of bioregulators on indole alkaloid biosynthesis

A study on the effect of various bioregulators on the biosynthesis of ajmalicine (8) and catharanthine (9) in plant tissue cultures of Catharanthus roseus is described. It is shown that 1,1-dimethylpiperidine bromide (3) and 2-diethylaminoethyl-3,4-dimethylphenylether (7) are effective in increasing these alkaloid levels in the cell line PRL #200. Such studies may prove beneficial in larger scale experiments designed for the production of these alkaloids.

Biotransformation of thebaine by cell suspension cultures of Papaver somniferum cv. Marianne

Abstract Thebaine is biotransformed to neopine by cell suspension cultures of Papaver somniferum cv. Marianne grown in O-B5 medium. Results of precursor stu