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A A Kiessling

Publications and source records attributed to A A Kiessling.

4 recordsLinked to original sources
PubMed1979

DNA polymerase activity in preimplantation mouse embryos.

DNA polymerase activity was measured in mouse embryos at stages before implantation to determine whether it increases in proportion to the amount of DNA synthesis, as it does in populations of differentiated mammalian cells, or remains constant, as it does in early sea urchin embryos. Total enzyme activity was found to be relatively unchanged following fertilization and in the first few cleavage stages. However, between the 12- and 120-cell (blastocyst) stage, the amount of activity increased by several-fold. These results indicate that the relationship between amount of DNA polymerase activity and DNA synthesis in mouse embryos exhibits two phases: in the early cleavage phase it is similar to that in sea urchin embryos, whereas, in the blastocyst phase, it is similar to that in differentiated mammalian cells.

Animals↗
PubMed1979

Detection of reverse transcriptase activity in human cells.

Samples of three nonmalignant and seven leukemic human cells were examined for DNA polymerase activity that could be identified as RNA tumor virus reverse transcriptase. Experiments on virus-infected model animal cells provided the basis for cell fractionation procedures, and reconstituted systems of known virus, added to human cells, established a threshold of virus detection by enzyme assay at 1 to 10 particles/cell. DNA polymerase activity with some properties similar to a reverse transcriptase was detected in some of the human leukemic cells. However, parallel analyses of nonmalignant cells showed sufficient similarities to raise serious questions about the specificity of the criteria. Reverse transcriptase activity has been reported to be present in white blood cells from a proportion of cases of leukemia; however, it is concluded from the present study that the usual enzymatic criteria using synthetic template primers, which were used in most of the studies reported, are not sufficient to identify a DNA polymerase activity as viral reverse transcriptase.

Animals↗