The effect of ribonucleosides and deoxyribonucleosides on the phosphorolysis of 5-fluoro-2'-deoxyuridine (FUdR) was examined in cells of Escherichia coli. All nucleosides tested except guanosine and deoxyguanosine inhibited phosphorolysis. By using genetically marked strains it was found that in vivo FUdR is a specific substrate of thymidine phosphorylase.

Culture Media↗

PubMed1970

Incorporation of 5-bromodeoxyuridine into DNA of wild type Escherichia coli and its use for the enrichment of auxotrophic mutants.

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Adenine Nucleotides↗

PubMed1970

Effect of adenosine and deoxyadenosine on the incorporation and breakdown of thymidine in Escherichia coli K-12.

Deoxyadenosine (AdR) and adenosine (AR) enhance the incorporation of thymidine (TdR) into bacterial deoxyribonucleic acid (DNA) by the inhibition of TdR phosphorolysis in vivo. Neither of the purine nucleosides has an effect on the reaction catalyzed by TdR phosphorylase in vitro. AdR induces TdR phosphorylase and both purine nucleosides induce purine nucleoside phosphorylase. AR can stimulate uptake of more TdR into bacterial DNA than AdR.

DNA, Bacterial↗

PubMedDate not supplied

A new fused transcript in Philadelphia chromosome positive acute lymphocytic leukaemia.

The leukaemic cells of more than 90% of chronic myelogenous leukaemia (CML) patients and of 10% of acute lymphocytic leukaemia (ALL) patients carry the t(9:22) (q34:q11) translocation which generates the Philadelphia chromosome (Ph1). In CML the abl gene is translocated from chromosome 9 to the centre of the bcr gene on chromosome 22 and this results in production of chimaeric bcr-abl RNA translated into a protein of relative molecular mass (Mr) 210,000 (210K). Our data indicate that in ALL abl is translocated into the 5' region of the bcr gene. The consequence of this is the expression of a fused transcript in which the first exon of bcr is linked to the second abl exon. This transcript encodes a 190K protein kinase.

Amino Acid Sequence↗

PubMedDate not supplied

Screening for highly active plasmid promoters via fusion to beta-galactosidase gene.

A plasmid containing promoter-deleted inactive beta-galactosidase gene [1] was used to select promoters of the pEP 121 plasmid [2]. Colonies of cells harboring reactivated beta-galactosidase gene were identified by their red color on McConkey plates. The quantitative amounts of beta-galactosidase produced in each clone were estimated by assaying enzyme activity and by measuring the specific beta-galactosidase protein following fractionation of total cells' proteins on polyacrylamide gel. A wide range of enzyme activities was observed. The most active promoter isolated was shown to promote beta-galactosidase production more efficiently, compared with the original beta-galactosidase promoter, amounting to 20% of all cell proteins. Such highly active promoters may be utilized in the future, to promote expression of cloned genes in bacteria.

Cloning, Molecular↗