PubMed Health⌕ Search

Biomedical subjects

W Plaut

Publications and source records attributed to W Plaut.

17 recordsLinked to original sources
PubMed1975

Alteration of Ringer pH and its effects on precursor incorporation into Drosophila salivary gland nuclei.

Drosophila salivary glands were explanted and incubated with 3-H-uridine (or 3-H-thymidine) in Ringer's solution (Ephrussi-Beadle modified saline) adjusted to pH values in the integral range, 4 to 10. The results of autoradiographic investigations indicate a differential effect of altering Ringer pH on 3-H-uridine as opposed to 3-H-thymidine incorporation: a) Relatively uniform levels of chromosomal incorporation of 3-H-thymidine occured over the range of test pH. Some decrease of incorporation was noted at pH 5 and some increase at pH 9. b) Chromosomal incoroporation of 3H-uridine was severely depressed at pH 4 and 7 relative to the high incorporation levels observed at other pH values. Controlling pH of Ephrussi-Beadle Ringer's solution in such experiments a necessity. This appears especially important for studies involving 3-H-uridine incorporation.

Animals↗
PubMed1973

Interaction of poly-L-lysine with chromatin. Inhibition of in situ RNA synthesis mediated by Escherichia coli RNA polymerase.

RNA polymerase from Escherichia coli was used in conjunction with labeled nucleosides as an autoradiographic reagent to study the availability of template in the chromatin of fixed nuclei and chromosomes Sequential treatments of the tissues with acid and poly-L-lysine were used to compare the effect of these treatments on the availability of template with the previously reported effects on the in situ priming for Escherichia coli DNA polymerase Acid treatment was found to increase the in situ activity of both enzymes, while poly-L-lysine strongly inhibited the in situ reactions mediated by RNA and DNA polymerases. When the DNA polymerase reaction was previously carried out on alcohol-fixed chicken blood smears, leukocyte nuclei primed extensively for DNA synthesis. In contrast, we did not detect incorporation into intact nuclei of any cell type in alcohol-fixed blood smears that were treated with RNA polymerase.

Animals↗
PubMed1972

Interaction of poly-L-lysine with chromatin. Inhibition of in situ priming for Escherichia coli DNA polymerase.

The priming capacity of chromatin of fixed nuclei and chromosomes for exogenous DNA polymerase can be evaluated radioautographically by the incorporation of labeled nucleotides. It had previously been reported that acid fixation or acid treatment of alcohol-fixed tissues led to increased priming when calf thymus DNA polymerases, specific for single-stranded DNA, were used. We employed Escherichia coli DNA polymerase and sequential treatments of the fixed tissue with acid and poly-L-lysine in order to elucidate the mechanism through which the acid effect is produced. Acid treatment enhanced chromatin priming for the E coli DNA polymerase, and saturation of the chromatin with poly-L-lysine strongly inhibited the reaction. This inhibition was reversible through subsequent treatment with acid. Wide differences in priming were observed between cell types of alcohol-fixed chicken blood smears: thrombocyte and lymphocyte nuclei exhibited strong priming ability whereas erythrocyte nuclei failed to support any detectable priming. We conclude that the acid effect is readily interpretable in terms of acid-mediated changes in the association between DNA and protein in the chromatin complex.

Acetates↗
PubMed1968

Chromosomal DNA synthesis in Drosophila melanogaster.

Analysis of labeling patterns in three chromosome segments of Drosophila melanogaster has shown that the replicative activity within chromosomes is temporally ordered. Moreover, specific labeling patterns on one chromosome occur with specific patterns on another chromosome with a very high degree of correlation. This circumstance leads to the conclusion that DNA synthesis among all the regions in the three chromosome segments studied is coordinated. The various labeling patterns observed in any one chromosome and the combinations of labeling patterns observed in all three chromosome segments can be arranged in ordered arrays, if one assumes that the DNA synthesis in each chromosome region will go to completion without stopping once it has started. Such arrays can serve as models for the temporal order of DNA synthesis among chromosome regions. They predict that in any one chromosome DNA replication begins and ends at very few loci and that synthesis at a larger number of points occurs at an intermediate time.

Autoradiography↗