Wheat embryo ribonucleates. XIV. Mass isolation of mRNA from wheat germ and comparison of its translational capacity with that of mRNA from imbibing wheat embryos.

Commercially milled wheat germ is shown to be a convenient source material for facile recovery of mass (milligram) quantities of highly purified poly(A)-rich RNA. This poly(A)-rich RNA is efficiently translated in a nuclease-treated extract of rabbit reticulocytes. By sucrose density gradient fractionation of bulk poly(A)-rich RNA from wheat germ, it has been possible to show that there is a direct relationship between the molecular weights of the polypeptide products of cell-free synthesis and the molecular weights of the wheat mRNA molecules which program their synthesis. As assessed by SDS -- polyacrylamide gel electrophoresis, the same array of polypeptides is synthesized when nuclease-treated reticulocyte extract is programmed by poly(A)-rich RNA from either commercially supplied or laboratory-prepared wheat embryos. Significantly, there are gross quantitative if not qualitative differences between the translational capacities of poly(A)-rich RNA from dry and imbibing wheat embryos, and the possible importance of these differences for interpreting a changing pattern of polypeptide synthesis in imbibing wheat embryos is the subject of a brief discussion.