Basler E
Plant Physiol. 1966 Mar;41(3):395-404. doi: 10.1104/pp.41.3.395.
The effects of light and glucose in the nutrient medium on the nucleic acid metabolism of excised 8-day cotton (Gossypium hirsutum var. Acala 44) cotyledons were determined. The rates of synthesis as affected by light and glucose were determined by brief exposures to C(14)-labeled orotic acid. The nucleic acids were fractionated by homogenizing in Tris-HCl buffer and centrifuging to obtain soluble and microsomal RNA (20,000 x g supernatant) and a particulate nucleic acid fraction (20,000 x g precipitate) or by extracting in phenol followed by 10% NaCl extraction at 100 degrees . The phenol extract was analyzed by density gradient centrifugation. Light and glucose caused parallel changes in nucleic acid levels of the various fractions, in orotic acid-6-C(14) absorption and in rates of synthesis of nucleic acids. Light and glucose appear to enhance binding of the ribosome nucleic acid so that it becomes less extractable in Tris-HCl buffer or phenol. The bound nucleic acids were labeled at a slightly higher rate than the total nucleic acids extracted by Tris-HCl or phenol. However, light treatment for 48 hours promoted a very high labeling rate in the soluble, low molecular weight nucleic acid as shown by density gradient centrifugation of the phenol extractable fraction.It was concluded that a part of the nucleic acid changes were brought about by light acting through the photosynthetic production of carbohydrate. This conclusion was strengthened by the observation that herbicide inhibitors of photosynthesis and limited atmospheric CO(2) concentrations partially inhibited the nucleic acid changes. However, glucose did not cause changes in nucleic acid levels as large as those caused by light and changes were observed to occur in light even though the endogenous sugar levels were maintained at a low level by the inhibition of photosynthesis with herbicides. The data indicated that light may produce changes in nucleic acid levels by other mechanisms additional to those regulating the sugar level in the tissue.
测定了营养培养基中的光照和葡萄糖对离体8天棉（陆地棉阿卡拉44品种）子叶核酸代谢的影响。通过短暂暴露于C(14)标记的乳清酸来测定受光照和葡萄糖影响的合成速率。通过在Tris-HCl缓冲液中匀浆并离心以获得可溶性和微粒体RNA（20,000×g上清液）以及颗粒状核酸部分（20,000×g沉淀），或通过在苯酚中提取，然后在100℃下用10% NaCl提取来分离核酸。通过密度梯度离心分析苯酚提取物。光照和葡萄糖导致各部分核酸水平、乳清酸-6-C(14)吸收以及核酸合成速率发生平行变化。光照和葡萄糖似乎增强了核糖体核酸的结合，使其在Tris-HCl缓冲液或苯酚中更难提取。结合的核酸标记速率略高于用Tris-HCl或苯酚提取的总核酸。然而，如苯酚可提取物的密度梯度离心所示，48小时的光照处理促进了可溶性低分子量核酸的非常高的标记速率。得出的结论是，核酸变化的一部分是由光照通过光合作用产生碳水化合物而起作用导致的。光合作用的除草剂抑制剂和有限的大气CO(2)浓度部分抑制核酸变化这一观察结果强化了这一结论。然而，葡萄糖引起的核酸水平变化不如光照引起的大，并且即使通过除草剂抑制光合作用使内源性糖水平维持在低水平，在光照下仍观察到变化。数据表明，光照可能通过调节组织中糖水平之外的其他机制引起核酸水平的变化。
