Ralph E. Alston

On the biogenesis of flavone O-glycosides and C-glycosides in the lemnaceae☆

Abstract 14C-Labeled apigenin, luteolin, orientin, isoorientin, and isovitexin were obtained either directly or by hydrolyzing the glycosides obtained from Spirodela and Lemna species which had been cultured on media containing phenylalanine-1-14C. The 14C-labeled flavones were introduced into the growth media for S. polyrhiza, S. oligorhiza and L. minor plants. When the extracts from these plants were chromatographed and the two-dimensional chromatograms examined autoradiographically, radioactivity was detected in O-glycosylated and O-methylated flavones. However, radioactivity was not detected in flavones containing new C-glycosyl linkages. The data suggest that plants in the Lemnaceae O-substitute flavones but do not C-glycosylate them. Moreover, evidence was obtained that flavones containing a 4′-monohydroxy B-ring can be oxidized to flavones with a 3′,4′-dihydroxy B-ring. None of the 14C-flavones was incorporated into any of the anthocyanins known to occur in the Lemnaceae. Isoorientin 3′-methyl ether and an O-β- d -glucoside of chrysoeriol were detected for the first time as constituents of L. minor.

Flavonoids from the genus tragopogon (compositae)

Abstract The known flavonoids apigenin, luteolin, 1μuteolin 7-O-β- d -glucoside, quercetin 3-O-β- d -glucoside, vitexin, isovitexin, vicenin-1, vicenin-2, swertisin, orientin, isoorientin, lucenin-1, lucenin-2, and swertia-japonin were identified as constituents of one or more of the five North American Tragopogon species. The distribution of these compounds is consistent with the genetic relationships between the species. A new C-glycosyl flavone, O-xylosylisovitexin, was detected in T. dubius .

Chromatographic Validation of Two Morphologically Similar Hybrids of Different Origins.

The origin of natural hybrids of the plant Baptisia was determined by chromatographic analyses of leaf extracts of both hybrid and parent plants. This method demonstrated a pattern of inheritance in the hybrid of certain species specific components of both parents.

The flavonoids of Psoralea (leguminosae)

Abstract The flavonoid patterns of thirty species of Psoralea were established by use of paper chromatography. A few compounds were identified only tentatively. Patterns of various species were generally similar and characterized by large amounts of di-C-glycosides, lesser amounts of 8-C- and 6-C-monoglycosides and small quantities of mixed C- and O-glycosides. Compounds not previously reported, tentatively identified as apigenin 6,8-di-C-glycoside, O-glucoside; luteolin 6,8-di-C-glycoside, O-glucoside; and chrysoeriol 6,8-di-C-glycoside, O-glucoside, occur in Psoralea rigida. An unidentified isoflavone occurs in two species.

Somatic mutation rates in double and triple heterozygotes of Impatiens balsamina following chronic gamma irradiation

Abstract A somatic mutation rate has been determined for petals of Impatiens balsamina heterozygous for flower color. The mutations are thought to result from marker loss of the dominant allele. The mutation rate for the L allele per r of daily exposure determined at 200 r/day was 1 in 0·76 × 10 6 cells. The dosage-response curve appears to be non-linear at the higher dose rates.

ON THE MECHANISM OF THE INHIBITION OF GROWTH BY XYLULOSE IN CHLOROCOCCUM ECHINOZYGOTUM1,2

We previously established that xylulose inhibits the growth of the green alga Chlorococcum echinozygotum. Utilizing experiments involving exposure of the alga to NaHC14O3, it was possible to show by counting the C14 activity of methanolic extracts of the algal cells that xylulose inhibited CO2 uptake. Subsequently it was shown that xylulose does not inhibit or otherwise influence the Hill reaction in this alga.

XYLULOSE, AN ALGAL GROWTH INHIBITOR12

The growth of Chlorococcum echinozygotum was previously known to be inhibited by an autoclaved solution of xylose in Bolds modified Bristols medium. We now report the isolation of 2 inhibitory compounds derived from xylose during autoclaving, and the identification of one of them as xylulose. Two strains of C. echinozygotum were isolated, one of which had physiologically adapted to xylulose. The growth rates of both strains were studied using varying amounts of xylulose. Cell counting studies indicated that the zoospores of the unadapted strain were most severely affected by xylulose inhibition and that the zygospores were most resistant.

A Symposium on Macromolecular Evolution: A Systematic Perspective

The symposium, Evolving Genes and Proteins, held at the Institute of Microbiology, Rutgers University, September 17-18, 1964, provided an excellent program in the form of a series of half-hour presentations by a distiinguished group of speakers. The program was devoted to: 1) the evolution of metabolic pathways; 2) the evolution of proteins; and 3) the evolution of genes. The symposium was, in effect, devoted to considerations of how a mo-