Biochemisch Laboratorium, Vrije Universiteit, de Boelelaan 1083, 1081 HV, Amsterdam, The Netherlands.
Plant Mol Biol. 1982 Jun;1(2):117-31. doi: 10.1007/BF00024975.
With the use of spinach chloroplast RNAs as probes, we have mapped the rRNA genes and a number of protein genes on the chloroplast DNA (cpDNA) of the duckweed Spirodela oligorhiz. For a more precise mapping of these genes we had to extend the previously determined [14] restriction endonuclease map of the duckweed cpDNA with the cleavage sites for the restriction endonucleases Sma I and Bgl I. The physical map indicates that duckweed cpDNA contains two inverted repeat regions (18 Md) separated by two single copy regions with a size of 19 Md and 67 Md, respectively.By hybridization with spinach chloroplast rRNAs it could be shown that each of the two repeat units contains one set of rRNA genes in the order: 16S rRNA gene - spacer - 23S rRNA gene - 5S rRNA gene.A spinach chloroplast mRNA preparation (14S RNA), which is predominantly translated into a 32 Kilodalton (Kd) protein [9], hybridized strongly to a DNA fragment in the large single copy region, immediately outside one of the inverted repeats. With another mRNA preparation (18S), which mainly directs the in vitro synthesis of a 55 Kd protein [9], hybridization was observed with two DNA regions, located between 211° and 233° and between 137° and 170°, respectively. Finally, with a spinach chloroplast genomic probe for the large subunit of ribulose 1,5-bisphosphate carboxylase [17], hybridization was found with a DNA fragment located between 137° and 158° on the map.
利用菠菜叶绿体 RNA 作为探针，我们已经将 rRNA 基因和一些蛋白质基因定位在浮萍的叶绿体 DNA（cpDNA）上。为了更精确地定位这些基因，我们必须扩展之前确定的[14]浮萍 cpDNA 的限制内切酶图谱，增加 Sma I 和 Bgl I 限制内切酶的酶切位点。物理图谱表明，浮萍 cpDNA 包含两个反向重复区（18Md），由两个单拷贝区隔开，大小分别为 19Md 和 67Md。通过与菠菜叶绿体 rRNAs 杂交，可以证明两个重复单元中的每一个都包含一套 rRNA 基因，顺序为：16S rRNA 基因-间隔区-23S rRNA 基因-5S rRNA 基因。菠菜叶绿体 mRNA 制剂（14S RNA），主要翻译为 32 千道尔顿（Kd）的蛋白质[9]，与大单拷贝区外一个反向重复单元的一个 DNA 片段强烈杂交。另一种 mRNA 制剂（18S），主要指导体外合成 55 Kd 的蛋白质[9]，与位于 211°和 233°之间以及 137°和 170°之间的两个 DNA 区域杂交。最后，用菠菜叶绿体基因组探针检测核酮糖 1,5-二磷酸羧化酶的大亚基[17]，在图谱上位于 137°和 158°之间的 DNA 片段发生杂交。
