Mouse histidyl-tRNAs during pregnancy. Differentiation of activity profiles within and between organs

Optimal conditions for in vitro formation of His-tRNA were established. Transfer RNA of maternal mouse organs and total embryo at 13 and 17 days of pregnancy was acylated in vitro with [3H] or [14C] histidine and examined by reversed-phase plaskon chromatography. Most tissues show different radioactive profiles reflecting a varying activity of six to eight isoaccepting His-tRNA species. Quantitative differences in profile were observed for liver tRNA during pregnancy. Profiles of embryo and uterus, kidney, heart and muscle changes less, and that of brain did not change during pregnancy. The significance of these observations with respect to molecular differentiation of His-tRNAs during pregnancy is discussed.