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H C Renger

Publications and source records attributed to H C Renger.

9 recordsLinked to original sources
PubMed1973

Surface changes in temperature-sensitive Simian virus 40-transformed cells.

A binding assay that shows consistent differences in the amounts of tritium-labeled concanavalin A that bind to normal and virally transformed cells was used to study the kinetic changes of cell surface in SV40-transformed 3T3 cells that express the transformed phenotype in a temperature-sensitive manner (tsSV3T3 cells). The increase in concanavalin A binding, which paralleled the appearance of the characteristics of transformed cells, was dependent on the synthesis of cellular DNA. In agreement with the results of binding studies, exponentially growing tsSV3T3 cells agglutinated at much lower lectin titers (concanavalin A as well as wheat-germ agglutinin) at 32 degrees than at 39 degrees .

Agglutination↗
PubMed1973

Temperature-sensitive simian virus 40-transformed cells: phenomena accompanying transition from the transformed to the "normal" state.

Temperature-sensitive simian virus (SV 40)-transformed 3T3 cells (tsSV3T3), which express the transformed phenotype when growing at 32 C but not at 39 C, were used to study changes in growth behavior during shift-up or shift-down experiments. In cultures of tsSV3T3 cells which had reached or were beyond monolayer density at 32 C, DNA synthesis reached very low levels within 24 to 48 h after shift-up. When cells which had been allowed to grow to high densities at 32 C were shifted to 39 C, not only cell growth stopped, but within two to three days the cultures shed a large number of cells into the medium. These cells were nonviable, and shedding stopped only when the number of cells attached had been reduced to that characteristic of the saturation density at 39 C. The remaining attached cells were viable and after the shift to 32 C were again able to grow from the monolayer to high cell densities. This behavior has been compared with that of normal 3T3 and wild-type SV3T3 cells under different conditions. We have also isolated new tsSV3T3 lines, using cells which had been infected with non-mutagenized wild-type SV40. This further demonstrates that the temperature sensitivity of these lines is due to a cellular rather than a viral mutation.

Animals↗
PubMed1972

Mutation causing temperature-sensitive expression of cell transformation by a tumor virus (SV40-3T3 mouse cells-growth control).

A procedure has been devised to isolate 3T3 mouse fibroblasts transformed by simian virus 40 (SV40) that express their transformed phenotype at low (32 degrees C) but not at high (39 degrees C) temperature. Three parameters typical of malignant growth in vitro: (a) high saturation density in culture, (b) ability to form colonies on monolayers of normal 3T3 cells, and (c) lack of contact inhibition of DNA synthesis, are temperature sensitive. These phenotypic changes are fully reversible. The serum requirement for growth appears to be largely unchanged by temperature. These cells seem to owe their behavior to a cellular, rather than to a viral, alteration since after fusion of the temperature-sensitive transformed cells with permissive monkey cells, a procedure that leads to rescue (i.e., multiplication of the virus), wild-type SV40 virus is produced.

Animals↗
PubMed1972

The form and structure of kinetoplast DNA of Crithidia.

Cesium chloride centrifugation of each of the DNAs extracted from eight strains of Crithidia revealed a main band at rho = 1.717 g/cm(3) and a satellite band varying from rho = 1.701 to 1.705 g/cm(3) for the different strains By electron microscopy each DNA was shown to include circular molecules, 0.69-0.80 micro in mean contour length, and large, topologically two-dimensional masses of DNA in which the molecules appeared in the form of rosettes. DNA isolated from kinetoplast fractions of Crithidia acanthocephali was shown to consist of light satellite DNA and to be mainly in the form of large masses, 0.8 micro (mol wt = 1.54 x 10(6) daltons) circular molecules, and a few long, linear molecules. The results of experiments involving ultracentrifugation, heating, and quenching, sonication, and endodeoxyribonuclease digestion, combined with electron microscopy, are consistent with the following hypothesis. The large DNA masses are associations of 0.8 micro circles which are mainly covalently closed. The circles are held together in groups (the rosettes) of up to 46 by the topological interlocking of each circle with many other circles in the group. A group of circles is attached to an adjacent group by one or more circles, each interlocking with many circles of both groups. Each of the associations comprises, on the average, about 27,000 circles (total mol wt approximately 41 x 10(9) daltons). A model is proposed for the in situ arrangement of the associations which takes into consideration their form and structure, and appearance in thin sections

Acridines↗
PubMed1970

Kinetoplast deoxyribonucleic acid of the hemoflagellate Trypanosoma lewisi.

Cesium chloride centrifugation of DNA extracted from cells of blood strain Trypanosoma lewisi revealed a main band, rho = 1.707, a light satellite, rho = 1.699, and a heavy satellite, rho = 1.721. Culture strain T. lewisi DNA comprised only a main band, rho = 1.711, and a light satellite, rho = 1.699. DNA isolated from DNase-treated kinetoplast fractions of both the blood and culture strains consisted of only the light satellite DNA. Electron microscope examination of rotary shadowed preparations of lysates revealed that DNA from kinetoplast fractions was mainly in the form of single 0.4 micro circular molecules and large masses of 0.4 micro interlocked circles with which longer, often noncircular molecules were associated. The 0.4 micro circular molecules were mainly in the covalently closed form: they showed a high degree of resistance to thermal denaturation which was lost following sonication; and they banded at a greater density than linear DNA in cesium chloride-ethidium bromide gradients. Interpretation of the large masses of DNA as comprising interlocked covalently closed 0.4 micro circles was supported by the findings that they banded with single circular molecules in cesium chloride-ethidium bromide gradients, and following breakage of some circles by mild sonication, they disappeared and were replaced by molecules made up of low numbers of apparently interlocked 0.4 micro circles. When culture strain cells were grown in the presence of either ethidium bromide or acriflavin, there was a loss of stainable kinetoplast DNA in cytological preparations. There was a parallel loss of light satellite and of circular molecules from DNA extracted from these cells.

Acridines↗