二氯苯氧乙酸(2.4-D)對大豆下胚軸細胞核內酸性蛋白質及其磷酸化作用的影響

Abstract

在暗中萌芽四天的大豆白化幼苗。經過2.5x103M2,4-D(PH6.0)處理後。分別於0小時（對照組）。12時及24小時切取下胚軸的成熟部份，做埋蠟切片，並且在顯微鏡下觀察各部份組織之變化及核仁的變大情形。經過2.4-D處理12小時後的皮層細胞核及核仁均有增大之現象，但核仁與細胞核的比值維持一定。維管束組織在處理2.4-D 12小時及24小時後細胞核的大小仍然保持不變，然而核仁的大小卻有顯著的增大，若與對照組相比較。在處理2.4-D 24小時後，核仁增大約50%，核仁與核的比值也增加。髓的細胞核和核仁經處理2.4-D後，其大小保持不變。大豆幼苗經2.4-D處理24小時後，植株變矮，但下胚軸仍有生長。若切取下胚軸膨大部份（3cm）測其鮮重、乾重及白質含量，與對照組比較。三者都比對照組大。 由下胚軸細胞核分離出的酸性蛋白質，經8.75% SDS acrylamide gel電泳分析，約可發現有35-40條蛋白質。處理組和對照組比較，二者蛋白質內樣型圖是相同的，然數條蛋白質帶發生量的改變，例如處理組在分子量32，000,40，000.61,000及90,000的蛋白質比對照組的量多。 經2.4-D處理後，結合在細胞核內的酸性蛋白質上的磷含量都比對熙組的高，在處理8小時達最高點，以後即開始下降。以核內酸性蛋白質量?舉，合磷量為0.1%到0.5%，視處理時間不同而異。又以同位素32P-phcaphate和14C-leucine測定2.4-D處理後對細胞核內酸性蛋白質的磷酸化作用和合成的影響。在膠質上，可發現處理組有三個32p的高?，其位置分別在分子量94,000,68,000與61,000處，此乃顯示該處的蛋自質的磷酸化增強，而14C-leucine標示，知蛋白質新合成情形與蛋自質的磷酸化作用增加是不一致的。 處理2.4-D後，細胞核內的酸性蛋白質不但在量上有變化，而且磷酸化作用也加強。很可能因此調節了核醣核酸的合成，使得核醣核酸大量累積。

Four-day old etiolated soybean seedlings were treated with 2.5x103M2.4-D(PH6.0)for up to 24 hr.The mature hypocotyls were cut at o hr.(control).12 hr.and 24hr.and from waich the paraffin cross sections were made.These cross sections were observed under a microscope and the diameters of nucleolus and nucleus of different tissues were measured.After 12-hr treatment,the size of uclei and nucleoli of the cortex cells beef came larger,but the ratio of the size of nucleolus relative to the nucleus was constant.The size of the nuclei of vascular tissue after 12 hr treatment had the same size as those of the control,however,the nucleoli were significantly enlarged,so that the ratio of the size of nucleolus to nucleolus was much higher than that of the control.The size of nucleoli and nuclei of the pith cells showed almost no change throughout 24 hr treatment. Using 8.75% SDS-acrylamide gel electro phoresis,the nuclear acidic proteins from soybean hypocotoyls were separated into 35 to 40 distinct bands .The electro-phoretic pattern of the nuclear acidic pro-teins from treated and untreated tissues were similar,but quantitative differences on some individual protein bands had molecular weights of 32,000;4.,000;61,000;90,000. The phosphorus content of the nuclear acid dic proteins was higher in treated hypocotyls than in the control up through 24 hr2.4-D treatment and at 8-hr-treatment the highest amount of phosphorus (5.13μg/mg acidic protein) was found in nuclear acidic proteins. Using 32p-orthophosphate,phosphorylation of the nuclear acidic proteins from treated tissues with three protein bands having a molecular weight of 94,000;68,000 and 61,000 were found phosphorylated during the 8 hr treatment.The increased phosphoylation in acidic nuclear proteins did not all coincide with the new protein did not all coincide with the new protein biosynthesis based on 14C-leucine incorporation. The quantitative changes in the nuclear acidic proteins and the increment of phose phorylation of these proteins by 2.4-D treatment at an early stage (8 hr treatment)indicates that the biosynthesis of RNA(rRNA)is regulated through the phos-phorylation of the nuclear acidic proteins.