We performed several checks on the underlying assumptions and procedures of the thymidine technique applied to stream bed sediments. Bacterial production rates were not altered when sediments were mixed to form a slurry. Incubation temperature did affect production rates. Controls fixed and washed with formaldehyde had lower backgrounds than trichloroacetic acid controls. DNA extraction by base...

Reichard and E&born (1) demonstrated that rats selectively incorporated thymidine-N16 as deoxyribonucleic acid thymidine, and their observation has been extended by numerous investigators to include many organisms and several isotopic labels. Tritiated thymidine has been particularly useful as a means of marking DNA for study by high-resolution radioautography (Z), and the histological distribu...

It has been reported that exogenously supplied thymidine and thymidine analogues, e.g. 5-bromodeoxyuridine, are specifically incorporated into chloroplast (B-component) D N A in Chlamydomonas reinhardtii (10). The chloroplast-specific incorporation is found in vegetative cells, but this specificity is lost during meiosis when both nuclear D N A and chloroplast D N A can be labeled by radioactiv...

The amino sugar, D-glucosamine, inhibits the preformed route of thymidine metabolism in rat C6 glioma cells. This inhibition results from a concatenation of several distinct effects, including the inhibition of thymidine uptake, the reduction of thymidine phosphorylation, and an increased leakage of thymidine to the extracellular space. Each of these effects, while ostensibly small in magnitude...

Thymidine kinase is a cell cycle-dependent marker that can be detected in the serum of patients diagnosed with many different types of cancer. Serum levels of thymidine kinase have also been shown to reflect the progression of cancer as well as an indication of the efficacy of chemotherapeutic intervention. A new monoclonal antibody assay for thymidine kinase has been developed, which is capabl...

The antibacterial activity of trimethoprim-sulfamethoxazole against 99 strains of Staphylococcus epidermidis was tested on media known to be low in thymidine content, as determined by screening with Streptococcus faecalis. Eighty-one percent of the isolates were susceptible by agar dilution. Trimethoprim-sulfamethoxazole was bactericidal against two strains of S. epidermidis when thymidine phos...

Continuous labelling of callus with H-thymidine results in intermittent peaks of H-DNA per chloroplast, showing synchrony of division. The increase in H-DNA could be due to several replication rounds, and the drop to successive plastid divisions without intervening DNA synthesis. The level of DNA-binding proteins in the chloroplast parallels the peaks of plastidal DNA synthesis; such pro...

Thymidine reutilization was studied in reutilized by the salvage pathway mdisingle cells of the rat bone marrow. cated that approximately 40-60 per cent Using 3H-TdR in parallel with 1251-UdR of the thymidine in the blast cells is in conunction with the autoradiographic supplied from DNA of dead cells. This technique, cells of the erythrocytic sevalue is similar to that reported preries, the me...

In order to determine whether newly born cells in the dentate gyrus of the adult rat express the neuronal marker, neuron-specific enolase, or the glial marker, glial fibrillary acidic protein, we performed combined immunohistochemistry and autoradiography on brains from adult rats perfused at various times ranging from 1 h to four weeks following [3H]thymidine administration. Light-microscopic ...

Whole cells of Lactobacillus acidophilus are capable of degrading thymidine to thymine, suggesting the presence of thymidine phosphorylase (or thymidine hydrolase). This activity was also demonstrated in cell-free extracts.