Biomedical subjects
Publications and source records attributed to T C Hall.
Methotrexate-promoted survival of mice bearing different transplantable leukemias was compared with uptake of the drug by leukemia cells in vitro. A high degree of correlation (r(2) = 0.88) showed that uptake may be a major determinant of the antitumor activity of methotrexate against transplantable mouse leukemias.
1. Inexpensive scintillation mixtures are described which enable the detection of as little as 40mumuc of (14)C in aqueous solution with an efficiency of counting of over 80%. 2. A rapid method for the counting of alkaline, acidic and neutral aqueous solutions of up to 1ml. volume is described. Ethanol or 2-ethoxyethanol is used as blending agent. 3. The scintillation counting of alkaline solutions is applied to the accurate determination of the specific activity of (14)C-labelled proteins from plant tissues. 4. Attention has been paid to the importance of a standardized washing procedure for the removal of all traces of radioactive material from glassware.
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A remarkable feature of the genomic RNAs of several plant viruses is the presence at the 3' end of a region that exhibits tRNA-like functions, including aminoacylation. The three genomic and single subgenomic RNAs of brome mosaic virus (BMV) accept tyrosine in vitro and in vivo, the smallest 3' fragment that can be aminoacylated being about 135 nucleotides long. The roles of the tRNA-like properties are incompletely understood, but an involvement in replication rather than translational functions is likely. We have recently shown (J.J.B. et al., in preparation) that the features recognized by the BMV RNA-specific RNA-dependent RNA polymerase (replicase) for the use of BMV RNA for complementary strand synthesis also lie within the tRNA-like structure. To distinguish between the roles of BMV RNA as a substrate for tyrosyl-tRNA synthetase and BMV replicase, we have now produced BMV RNAs with mutations at two separate loci within the tRNA-like structure. This has been achieved by transcription in vitro from specifically mutagenized cDNA, an approach permitting the generation of targeted mutants without regard to their viability in vivo.