Lee L, Tsai C Y
Biochem Genet. 1984 Aug;22(7-8):729-37. doi: 10.1007/BF00485856.
Zein synthesis in the developing (22 and 50 days postpollination) endosperm and embryo of maize (Zea mays L.) double mutants, brittle-1; opaque-2 and brittle-2;opaque-2, were compared and correlated with sucrose concentration and RNase activity in order to test the hypothesis that high sucrose concentrations may prevent the interaction between zein polyribosomes and endoplasmic reticulum and make the zein mRNAs more susceptible to hydrolysis by high RNase activity, resulting in a severe reduction in zein synthesis. The double-mutant combinations of opaque-2 with each of the starch-deficient mutants, brittle-1 and brittle-2, maintained not only a high sucrose concentration in the endosperm but also a higher RNase activity than either one of the single mutants alone. Consequently, these double mutants severely suppressed the synthesis of two major zein components in their endosperms. In contrast to the endosperm system, embryos of the double mutants produced amounts of zein (and electrophoretic patterns) similar to that of the opaque-2 embryo, and their embryos contained levels of sucrose and RNase activity comparable to that of the o2 and normal control. These results are consistent with the notion that a posttranscriptional degradation of zein mRNAs by RNase, rather than a specific transcriptional block, is involved in the endosperm to suppress zein synthesis in these double mutants.
对玉米（Zea mays L.）双突变体脆-1；不透明-2和脆-2；不透明-2发育中的（授粉后22天和50天）胚乳和胚中的玉米醇溶蛋白合成进行了比较，并与蔗糖浓度和核糖核酸酶活性相关联，以检验以下假设：高蔗糖浓度可能会阻止玉米醇溶蛋白多核糖体与内质网之间的相互作用，并使玉米醇溶蛋白信使核糖核酸更容易被高核糖核酸酶活性水解，从而导致玉米醇溶蛋白合成严重减少。不透明-2与淀粉缺陷型突变体脆-1和脆-2的双突变体组合，不仅在胚乳中维持了高蔗糖浓度，而且核糖核酸酶活性也高于任何一个单突变体。因此，这些双突变体严重抑制了其胚乳中两种主要玉米醇溶蛋白成分的合成。与胚乳系统相反，双突变体的胚产生的玉米醇溶蛋白量（和电泳图谱）与不透明-2胚相似，并且它们的胚中蔗糖和核糖核酸酶活性水平与o2和正常对照相当。这些结果与以下观点一致，即在这些双突变体中，胚乳中玉米醇溶蛋白信使核糖核酸的转录后降解而非特定的转录阻滞参与了对玉米醇溶蛋白合成的抑制。
