NOVEL ARRANGEMENT OF 18S AND 28S SEQUENCES IN A REPEATING UNIT OF DROSOPHILA-MELANOGASTER RDNA
NOVEL ARRANGEMENT OF 18S AND 28S SEQUENCES IN A REPEATING UNIT OF DROSOPHILA-MELANOGASTER RDNA
复制标题
DOI：
10.1016/0092-8674(77)90212-4
复制
发表时间：
1977-01-01
期刊：
影响因子：
64.5
通讯作者：
HOGNESS, DS
中科院分区：
文献类型：
--
作者：
GLOVER, DM;HOGNESS, DS
对应于18S和28SrRNA的序列被定位在由D.黑腹果蝇核糖体DNA。该片段Dm103代表存在于该果蝇rDNA中的两种主要类型的重复单元中较长的一种，并被克隆为杂合质粒pDm103，其由插入到pSC101载体的Eco R1位点的Dm103组成。Dm103中18S和28S rDNA的定位通过定量测定这些rDNA在通过Hind III和Eco R1切割pDm103获得的一组有序限制性片段的每个成员中的量来完成。18S和28S rDNA的量通过rRNA与通过克隆纯化的片段的杂交来确定，并且通过异源双链体作图和片段长度的化学计量来建立pDm103内片段的明确顺序。由此得到的图谱显示，由Dm103代表的长重复单元内的4kb的28S rDNA被分成2个块，这2个块被5.4kb的未知功能的DNA分开。28S rDNA的这种不寻常的排列将长重复单元（17 kb）与短重复单元（11.5 kb）区分开来，后者的4 kb 28S rDNA被限制在一个单一的块中。在这个长单位中的DNA的其余部分似乎是典型地排列的，其中2kb的18S rDNA被限制在一个单一的块中，该块与最近的28S rDNA块相隔约1kb。
The sequences corresponding to the 18S and 28S rRNA were mapped within a cloned 17 kilobase (kb) fragment formed by Eco R1 cleavage of D. melanogaster rDNA [ribosomal DNA]. This fragment, Dm103, represents the longer of 2 major types of repeating units that are present in the rDNA of this fly, and was cloned as a hybrid plasmid, pDm103, consisting of Dm103 inserted at the Eco R1 site of the pSC101 vector. Mapping of the 18S and 28S rDNA in Dm103 was accomplished by quantitative determination of the amount of these rDNA in each member of an ordered set of restriction fragments obtained by Hind III and Eco R1 cleavage of pDm103. The amounts of 18S and 28S rDNA were determined by hybridization of the rRNA to fragments that were purified by cloning, and an unambiguous order of the fragments within pDm103 was established by heteroduplex mapping and from the stoichiometry of the fragment lengths. The resulting map revealed that the 4 kb of 28S rDNA within the long repeating unit represented by Dm103 is divided into 2 blocks that are separated by 5.4 kb of DNA of unknown function. It is this unusual arrangement of the 28S rDNA that distinguishes the long repeating units (17 kb) from the short units (11.5 kb), whose 4 kb of 28S rDNA is confined to a single block. The remainder of the DNA in this long unit appears to be typically arranged, with the 2 kb of 18S rDNA confined to a single block that is separated by about 1 kb from the closest block of 28S rDNA.