Twenty-four-four rhythm in DNA synthesis, mitotic activity and mitosis duration in ascites tumor NK/LY
Moskalik, K.G.
Neoplasma 25(3): 291-296
1978
ISSN/ISBN: 0028-2685 PMID: 683374 Document Number: 127174
In experiments in male mice of the SHR line 24 h changes of mitotic activity, DNA synthesis with the help of H3-thymidine and mitosis duration with the use of the colchicine technique in the ascites leukemia NK/LY during 3 days of growth were investigated. The experiments were done in the autumn. Mice were killed every 3 h during 24 h. One hour before decapitation the mice received an i.p. injection of 0.5 .mu.Ci/g H3-thymidine. Six hours before decapitation mice received an i.p. injection of 1 .mu.g/g colchicine. The tumor showed a characteristic circadian rhythm in DNA synthesis, mitotic activity and mitosis duration. The monophasic circadian rhythm of the division of cells with the maximum number of mitosis in dark hours is characteristic for this tumor. The curve of 24 h variations in the number of labeled cells is close in its character to the curve of mitotic activity changes. The number of Ag grains over the labeled tumor cell nuclei varied during the day in conformity with DNA synthesis variations. In the periods of mitotic activity rise, mitosis duration did not grow. The change of the circadian rhythm of cell reproduction is the sequence of a different number of dividing tumor cells, and not the result of a change of mitosis duration.