AKR Mouse Cells Research Articles

FUNCTIONAL PROPERTIES OF THE ACENTRIC CHROMOSOME FRAGMENTS OF MOUSE LEUKEMIA CELLS.

Abstract The present investigation was undertaken to increase our understanding of the behavior of the acentric chromosome fragments after they form micronuclei in the cytoplasm. Lymphocytic leukemia cells of AKR mice carried in the ascites form was used in this study. Chromosome fragmentation leading to the formation of micronuclei was induced by an alkylating agent, cyclophosphamide. The ability of the micronuclei to synthesize DNA was determined by the incorporation of 3H-thymidine, studied by stripping film autoradiography. The silver staining technique was used to detect the presence of nucleolar bodies in the micronuclei. Squash preparations of Giemsa stained cells were also examined to study the morphological nature of the micronuclei during mitosis. The data showed that the micronuclei which contain an appropriate amount of nucleolar material are active in DNA synthesis, although some tend to do so asynchronously with the main nucleus. However, in most part they do not enter mitosis. This finding thus indicates that fragmentation by itself does not seem to impair the genetic function of the cell. The deleterious consequence appears to be the inability of the micronuclei to enter mitosis and their subsequent random distribution into the daughter cells at telophase.

The Colchicine Method in the Study of Bone Marrow Cell Proliferation

Abstract The rate of metaphase accumulation in the bone marrow cells of AKR mice treated with colchicine was investigated. The influence of this alkaloid on the differential count of the bone marrow cells in these animals was also studied. It was demonstrated that the stathmokinetic effect of colchicine on the bone marrow cells started almost immediately after the administration of the drug. The number of arrested metaphases increased linearly from one-half hour to six hours after the injection of colchicine, and then fell rapidly. In rats injected with colchicine, the changes in the bone marrow concentration of this compound were followed for eight hours. The colchicine concentrations increased from the first to the fourth hour, and then fell rapidly, reaching the zero level at the eighth hour. From the results obtained, it appeared that four hours post-injection was the most convenient time for the study of the bone marrow proliferative activity by the colchicine method when 1.2 mg./Kg. of colchicine per body weight was used. The fact that four hours after the injection, a mild decrease in the percentage of mature bone marrow granulocytes was found, may represent a limiting factor, which is, however, of moderate importance in the application of this technic.