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D J Armstrong

Publications and source records attributed to D J Armstrong.

At least 73 records · Page 4Linked to original sources
PubMed1976

Cytokinins in Corynebacterium fascians Cultures: Isolation and Identification of 6-(4-Hydroxy-3-methyl-cis-2-butenylamino)-2-methylthiopurine.

In addition to the four cytokinins, 6-(3-methyl-2-butenylamino)purine, 6-methylaminopurine and the cis and trans isomers of 6-(4-hydroxy-3-methyl-2-butenylamino)purine, reported earlier from our laboratories, three cytokinin-active fractions have been obtained from the aqueous medium of 6-day-old Corynebacterium fascians cultures. One of these has been identified as 6-(4-hydroxy-3-methyl-cis-2-butenylamino)-2-methylthiopurine (2-methylthio-cis-zeatin, c-ms(2)io(6) Ade).The elution volumes of the other two fractions correspond to those of authentic 6-(4-hydroxy-3-methyl-2-butenylamino)-9-beta-d-ribofuranosyl-purine and 6-(3-methyl-2-butenylamino)-9-beta-d-ribofuranosylpurine, indicating the presence of trace amounts of these two ribonucleosides.

Journal Article↗
PubMed1975

An analysis of five serine transfer ribonucleic acids from Drosophila.

Crude tRNA from adult Drosophila melanogaster was fractionated on bensoylated-diethylaminoethyl cellulose columns. The eluate was assayed for both amino acid acceptance and cytokinin activity. Most of the cytokinin activity was associated with a peak of serine acceptance. The five major serine tRNAs were purified by chromatography on benzoylated-dietyhlaminoethyl cellulose and reversed phase chromatography-5 columns. The major species, tRNA7-Ser was isolated from this tRNA and was shown to be N-6-(delta-2-isopentenyl)adenosine (i-6A) on the basis of ultraviolet and mass spectral data. The nucleoside somposition of all five serine tRNAs was determined directly and by the 3-H derivative method. They all contain pseudouridine, ribothymidine, 1-methyladenosine, 5-methylcytosine, N-2-dimethylguanosine, 5, 6-hydrouridine, and 3-methylcytosine, while two contain an unidentified nucleoside, and one containes 1-methylguanosine. These techniques also confirmed the presence of i-6A in tRNA7-Ser as well as showing its presence in tRNA6-Ser and tRNA4-Ser. These three tRNA-Ser species exhibit marked changes in elution from reversed phase chromatography-5 columns as a function of temperature and this may be related to their minor base composition. The tRNAs-Ser were bound to ribosomes in response to the following triplets: tRNA2-Ser, AGU, AGC; tRNA4-Ser, UCG; tRNA5-Ser, AGU, AGC; tRNA7-Ser, UCG.

Adenosine↗
PubMed1975

Maturation of a hypermodified nucleoside in transfer RNA.

E. coli C6 rel- met- cys- was cultured in a fully supplemented medium and in media lacking cysteine or methionine. tRNA isolated from the three cultures containted, respectively, a normal complement of modified nucleosides; a deficiency in thiolated nucleosides and a deficiency in methylated nucleosides. Both sulfur-deficient tRNA and methyl-deficient tRNA contained large amounts of N-6- (delta-2-isopentenyl) adenosine and small amounts of the 2-methylthio derivative. Methyl-deficient tRNA contained, in addition a large amount of a cytokinin active, differently modified nucleoside that is believed to be a sulfur derivative of N6-(delta-2-isopentenyl) adenosine. The structure of this compound is unknown. When methly-deficient tRNA and the precusor the tRNA-Tyr su3-+ A25 were enzymatically methylated in vitro, methyl groups were incorporated into derivatives of isopentenyladenosine. These results indicate that the biosynthesis of the 2-methylthio derivative of isopentenyladenosine may occur in a sequential manner, i.e., thiolation of isopentenyladenosine followed by methylation.

Adenosine↗
PubMed1975

Chromatography of Cytokinins on a Neutral Polystyrene Resin: A Simple Procedure for the Separation of the cis and trans Isomers of Zeatin or Ribosylzeatin.

A simple procedure for the separation of the cis and trans isomers of zeatin and ribosylzeatin by column chromatography on a neutral polystyrene resin, Porapak Q, in aqueous ethanol solutions is reported. The method has been used to examine the stereoisomer composition of ribosylzeatin isolated from wheat germ transfer RNA. Chromatographic data for several other cytokinins are also presented.

Journal Article↗
PubMed1975

Incorporation of mevalonic Acid into ribosylzeatin in tobacco callus ribonucleic Acid preparations.

The incorporation of (14)C-2-mevalonic acid into transfer RNA and ribosomal RNA (high molecular weight RNA) in rapidly growing, cytokinin-dependent tobacco (Nicotiana tabacum var. Wisconsin No. 38) callus cultures has been investigated. Approximately 40% of the label incorporated into transfer RNA was present in a ribonucleoside with chromatographic properties identical to those of cis-ribosylzeatin. The remainder of the label in the transfer RNA appears to be nonspecific incorporation resulting from degradation and metabolism of (14)C-2-mevalonic acid by the tobacco callus tissue. Although the total radioactivity incorporated into ribosomal RNA was roughly the same as in transfer RNA, the specific radioactivity of the transfer RNA was about four times higher than that of the ribosomal RNA, and the ribosomal RNA labeling could be distinguished from the cytokinin labeling observed in transfer RNA. The distributions of the (14)C-2-mevalonic acid label and cytokinin activity in tobacco callus transfer RNA fractionated by benzoylated diethylaminoethylcellulose chromatography indicate that at least two cytokinin-containing transfer RNA species are present in this tissue.

Journal Article↗
PubMed1973

Isolation of cis-Zeatin from Corynebacterium fascians Cultures.

Three cytokinin-active constituents have been isolated from the culture medium of Corynebacterium fascians, a plant pathogen causing fasciation. One constituent is now identified as cis-zeatin [6-(4-hydroxy-3-methyl-cis-2-butenylamino)purine]. It represents the first unequivocal demonstration of the production of a zeatin isomer by a bacterial species. Another constituent was identified earlier as 6-(3-methyl-2-butenyl-amino)purine. The third constituent, distinct, on Sephadex LH-20 column chromatography, from the above two and their ribosides, has not yet been identified.

Journal Article↗
PubMed1969

Cytokinin of wheat germ transfer RNA: 6-(4-hydroxy-3-methyl-2-butenylamino)-2-methylthio-9-beta-D-ribofuranosylpurine.

A new modified nucleoside is responsible, in part, for the cytokinin activity of transfer RNA from wheat germ. The structure as judged by mass spec-trometry is 6-(4-hydroxy-3-methyl-2-butenylamino)-2-methylthio-9-beta-D-ribofuran-osylpurine. Unequivocal synthesis afforded material having ultraviolet, mass spectral, and chromatographic properties identical with those of the natural product.

Chromatography↗
PubMed1969

Cytokinins: distribution in species of yeast transfer RNA.

Transfer RNA fractions from Saccharomyces lactis and Saccharomyces cerevisiae have been tested for cytokinin activity in the tobacco bioassay. Cysteine tRNA has been identified as a cytokinin-containing tRNA species in S. cerevisiae. Acid hydrolysates of S. lactis tRNA fractions (containing arginine tryptophan, and valine acceptor activities) and S. cerevisiae tRNA fractions (containing alanine, asparagine, aspartic acid, glutamic acid, glycine, histidine, tryptophan, and valine acceptor activities) were inactive in the tobacco bioassay. Cytokinins have been found only in those tRNA species corresponding to codons beginning with U.

Biological Assay↗
PubMed1969

Cytokinins: distribution in transfer RNA species of Escherichia coli.

This distribution of cytokinin activity in tRNA species of Escherichia coli has been determined. Cytokinin activity was restricted to tRNA species recognizing codons with the initial letter U. The following have been shown to contain a cytokinin: tRNA(Phe), tRNA(Leu) UUG, tRNA(Ser)UC(G) (A), tRNA(Tyr), and tRNA(Try). tRNA(Cys) was present in fractions with cytokinin activity but was not sufficiently pure to prove it to be active. One tRNA(Ser) UC(C) (U) species was inactive. All major tRNA species recognizing condons with initial letters other than U were devoid of cytokinin activity in the tobacco bioassay. The significance of these findings is discussed as providing a possible mechanism of quantitative modulation at the translation stage of gene-controlled protein biosynthesis.

Cell Division↗