CHANGE OF STEMLINE KARYOTYPES IN YOSHIDA SARCOMA BY APPEARANCE OF PECULIAR MARKER CHROMOSOMES

Abstract

In the Yoshida rat sarcoma, two peculiar marker chromosomes in metaphase cells were recently observed in several stocks maintained in Japan. These two elements, one a large LS-marker and the other a small SS-marker, were characterized by an abnormally elongated part of the chromosome resembling a long satellite. The length of the quasi-satellite was different in different cells. Similar LS- and SS-markers were found in stocks maintained in Sasaki Institute, Tokyo, National Institute of Genetics, Mishima, Gifu Univeristy, Gifu, and Tohoku University, Sendai, but the LS-marker in the stock of Biological Research Laboratories of Takeda Chemical Ind., Ltd., Osaka, had a different shape, as if a small chromosome were united to the end of a long satellite. Frequency of the LS- and SS-markers was markedly different in different stocks. Higher frequency of markers was observed in those at Sasaki Institute, National Institute of Genetics, and Takeda Biological Research Laboratories, slightly lower in those at Gifu University, and very low in that at Tohoku University. The SS- and LS-markers at times had the appearance of satellite association. From the record of distribution of the tumor stocks, it is suggested that mutant cells with the peculiar markers occurred originally in Sasaki Institute, and then were propagated in several institutes in Japan. In Takeda's stock, translocation seems to have occurred secondarily in the LS-marker.