ISOACCEPTING TRANSFER RNA'S OF L-M CELLS IN CULTURE AND AFTER TUMOR INDUCTION IN C ₃ H MICE

Abstract

Abstract.-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 C3H mice by subcutaneous injection of L-M/I 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.The multiplicity of tRNA's accepting the same amino acid (isoaccepting tRNA's) has been well documented in lower and higher organisms (see Yang and Novellil for review). Apgar and Holley2 first reported that rat liver and yeast showed different patterns of isoaccepting tRNA's. Other studies have demonstrated that different chromatographic profiles of certain tRNA's were obtained during T2 phage infection in E. coli, I, 4 and during shifts of culture conditions in microorganisms.5 6 Similarly, different profiles have been demonstrated in organisms at different phylogenetic levels,7 in different mammalian tissues and organs,8 in tissues of the same kind that produce different proteins,9 in cells from different stages of development,10 and in cytoplasmic and mitochondrial fractions of cells.11 12 In this communication, we will present the results of a study on tumor formation by L-M cells, a subline of the clone 929 of L cells13 that has grown in a serum-free medium since 1958.14 These cells still retain the capacity of tumorigenesis in the C3H/Anf mice15 from which the original explant of normal subcutaneous connective tissue was taken in 1940.16 0.5% Bacto-peptone (199-P), were harvested by centrifugation and either used fresh or stored frozen at -700C until used. To obtain L-M tumors, 1 X 107 viable cells in 1 ml volume were injected into the left thigh of 7-week-old C3H/Anf male and female mice which had been irradiated with 425 R of X rays 4 hr previously. At 14 days the animals were decapitated and the tumors excised carefully from the surrounding tissue. The 1411

The effects of hyperphenylalaninaemia on the concentrations of aminoacyl-transfer ribonucleic acid in vivo. A mechanism for the inhibition of neural protein synthesis by phenylalanine

“…Three discrete peaks of brain methionyl-tRNA were resolved by this procedure. This profile is similar to that observed for other eukaryotic systems by using this same chromatographic material (Caskey et al, 1967;Yang et al, 1969;Crystal et al, 1972;Wang et al, 1974).…”

Chromatographic Analyses of Isoaccepting tRNAs from Avian Myeloblastosis Virus

“…We have also studied lysyl-tRNA by RPC-5 in control and murine sarcoma virus (Kirsten)transformed mouse cells and, similarly, we find four isoaccepting species (Gallagher, unpublished data), indicating that this lysyl-tRNA complement is not peculiar to chicken cells. In this regard, it is noteworthy that earlier reversed-phase chromatographic systems (RPC-2) resolved only two or three species of mammalian lysyl-tRNA (12,28). Therefore, we feel that the difference described by Travnicek and Riman in AMV (23) is probably due to artifactual differences which may attend chromatographic runs with inadequate resolution (21), although we cannot absolutely exclude the existence of a chemical difference which is resolved by MAK chromatography and not by RPC-5.…”

The role of queuine in the aminoacylation of mammalian aspartate transfer RNAs

“…Significant losses in the G-to-Q modification of tRNAs from several sources have been reported, for example, in tRNAs from prenatal mice (6), oneweek old rats (7), animals raised on a Q-free diet in a germ-free environment (8), and in tumor cells (2,(9)(10)(11)(12)(13). A small amount of Q-deficient tRNA is also reported in tRNAs from other sources (7,14).…”