We investigated conditions for the incorporation of thymidine-3H into pools of thymidine compounds and into DNA in mouse embryo cells in culture with the purpose of measuring changes in pool sizes and their possible correlation to the rate of DNA synthesis. Thin and dense cultures of embryo cells were grown in Petri dishes during six days. Thymidine triphosphate was the dominating thymidine com...

We have constructed a recombinant adenovirus that carries the herpes simplex virus type I gene for thymidine kinase (EC 2.7.1.21) and expresses thymidine kinase under control of adenovirus major late promoter. A DNA fragment carrying thymidine kinase coding sequences but lacking the thymidine kinase promoter was sandwiched between a piece of adenoviral DNA and simian virus 40 early DNA on a pla...

In thymidylate synthase-negative mutants of mouse FM3A cells, thymidine starvation rapidly decreased mitotic activity and resulted in cell death (thymineless death). When the thymidine starvation was reversed by an addition of thymidine, mitotic activity was recovered, but the majority of mitotic cells exhibited extensive chromosome aberrations, including chromatid breaks, chromatid exchanges, ...

A long-acting thymidine pellet consisting of 190 mg of cholesterol and 60 mg of thymidine has been developed for the study of thymidine metabolism and reutilization in vivo. Implantation of such a pellet s.c. in adult mice will maintain the blood plasma concentration of thymidine at levels between 40 and 8 X 10(-6) M, which are from 36 to 7 times those of normal mice, for periods up to 48 hr. D...

Mitochondrial (mt) neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disease associated with depletion, deletions, and point mutations of mtDNA. Patients lack a functional thymidine phosphorylase and their plasma contains high concentrations of thymidine and deoxyuridine; elevation of the corresponding triphosphates probably impairs normal mtDNA replication and repair. T...

Accumulating evidence indicates that the initiation of deoxyribonucleic acid synthesis is intimately associated with the appearance of elevated levels of enzymes involved in the synthesis of thymidine triphosphate. Thus, enhanced levels of such enzymes as thymidine kinase (l-11), thymidylate kinase (5-7, 12I4), thymidine diphosphate kinase (6,7), thymidylate synthetase (10, 15, 16), and deoxycy...

The behavior of the activities of thymidine metabolizing enzymes, dihydrothymine dehydrogenase (EC 1.3.1.2) and thymidine phosphorylase (EC 2.4.2.4) for thymidine degradation, thymidine kinase (EC 2.7.1.75) and thymidylate synthase (EC 2.1.1.45) for DNA synthesis, was elucidated in cytosolic extracts from normal human lymphocytes and 13 human leukemia-lymphoma cell lines. In the normal human ly...

When Chlamydomonas reinhardi is supplied with (methyl-(3)H)-thymidine, radioactivity is incorporated specifically into chloroplast DNA Chromatographic analysis of the products of enzymatic hydrolysis of the DNA reveals that only thymidine monophosphate has been labeled. Use of thymidine-6-(3)H yields an identical result. If thymidine-(3)H monophosphate is supplied, a small amount of radioactivi...

The effect of tritiated thymidine on the rate of entry of cells into mitosis was studied in mice; 1-5 /tc of tritiated thymidine (specific activity 5 c/mM) per g body weight did not alter the rate of entry. Other workers have reported an increased number of mitoses following administration of larger amounts of thymidine than those used in the present work; the suggestion is therefore made that ...

Thymidine-phosphorylating capacity, mediated by thymidine kinase or a nucleoside phosphotransferase, is closely correlated with DNA synthesis and cell division in a wide variety of bacterial, animal, and plant systems (4, 5, 11, 14, 17, 22). In cells that are not undergoing DNA synthesis and cell division, these enzymes are usually low or undetectable. Conversely, systems undergoing rapid DNA s...