ALKALINE PHOSPHATASE ACTIVITY OF L-M MOUSE CELLS AND VARIANTS

Isoaccepting transfer RNA's of L-M cells in culture and after tumor induction in C3H mice

Co-chromatography in a reversed-phase column was performed for 16 aminoacyl-tRNA's prepared from L-M cells grown in serum-free suspension culture and from tumors induced in irradiated C(3)H mice by subcutaneous injection of L-M cells. The results showed that between the two sources there were (1) marked differences in aspartyl-, histidyl-, phenylalanyl-, and tyrosyl-tRNA's; (2) significant quantitative differences in isoaccepting species of alanyl-, isoleucyl-, seryl-, and threonyl-tRNA's; and (3) similar to minimally different patterns of arginyl-, methionyl-, prolyl-, tryptophanyl-, valyl-, glycyl-, leucyl-, and lysyl-tRNA's. The differences were evident when synthetases prepared either from L-M cells or from the tumors were used. When the L-M tumors were brought back into in vitro culture, their tRNA patterns were like those of L-M cells. Addition of serum to the culture medium caused the L-M cells to show very minute, but detectable, amounts of the isoaccepting tRNA's found in the tumors. The cellular mechanisms which may be related to the changes of tRNA patterns in the L-M cells are discussed.