大豆下胚軸核醣核酸聚合?活性與蛋白質合成能力相關性之研究

Abstract

大豆下胚軸頂端切離部份，在磷酸緩衝液（phosphate buffer）培養8至12小時，頂端部份核醣核酸聚合?I（RNA polymeraseI）的活性與蛋白質合成能力（polyribosome level）顯著的降低。 無機鹽（inorganic salt）、生長調節劑（growth regulator）、胺基酸源（amino acid source）對核醣核酸聚合?I活性的維持均有重大的影響。而含酵母焠取物（yeast extract）的B5配方培養液維持細胞活性，相對提高核醣核酸聚合?I活性與蛋白質合成能力，比其他的含酵母焠取物、椰子汁（coconut milk）、或乳酪素水解物（Casein hydrolysate）的MS. White. ER配方培養液，及含椰子汁或乳酪素水解物的B5配方培養液有較好的效果。核醣核酸聚合?I活性與蛋白質合成能力間好像有很密切的正相關存在。推測這種現象的產生是與大腸菌（E. coli）的stringent菌株（strain）胺基酸匱乏（amino acid starvation）所造成的stringency，有相似控制核醣體核醣核酸（ribosomal-RNA r-RNA）合成的機制。

When exeised hypocotyl segments (0-0.5 cm) of dark-grown seedlings were incubated in phosphate buffer medium for 12 hours, the RNA polymerase I activity in the isolated nuclei decreased markedly relative to the RNA polymerase II activity. The level of polyribosome (protein synthetic activity) also decreased during the incubation period. It appears that there is a correlation between the RNA polymerase I activity and the level of polyribosome. Inorganic salts (macro-and micro-nutrients) such as MS or White, or B5 medium with plant growth hormones, which are commonly used in soybean tissue culture, in combination with either casein hydrolysate, yeast extract or coconut milk were used during the inoubation period to find whether the dissociation of the polyribosome could be prevented and the original RNA polymerase I activity be maintained. The B5 medium with yeast extract was found to be the most effective of the nutrients tested to maintain the RNA polymerase I activity up to 51% of the original activity. The level of polyribosome with this incubation medium was 47% which was 79% of the original polyribosome level. This substantiation shows the relationship between the level of polyribosome and the RNA polymerase I activity.