Localization of the Genes for Ribosomal RNA and th...
The 16S，23S and 5S rRNA genes of N.tabacum have been identified to reside on EcoRI fragments 8，4 and 29 respectively（Sugiura and Kusuda，1979；Fluhr and Edelman，1981）.These fragments were used as probes to localize rRNA genes in the cloned BamHI fragments of N.otophora ct-DNA.Figure 4 shows that the 32P-labeled EcoRI fragment 8（E8）of N.tabacum ct-DNA containing the 16S rRNA gene hybridized specifically with BamHI fragment 11（Bll）and SmaI 4（S4）of N.otophora ct-DNA.Similarily，the EcoRI fragment 4（E4）containing the 23S rRNA gene hybridized with BamHI fragment 5（B5），11（Bll）and SmaI fragment 11（Sll）（data not shown）.Thus，the Bll and B5 of N.otophora ct-DNA contain the 16S and 23S rRNA genes.Likewise，the EcoRI fragment 29（E29）containing 5S rRNA gene hybridized with B5 and S14.As in the case of both EcoRI（E8，E4 and E29）and SmaI（S4，Sll and S14）fragments，Bll and B5 are also doublets（see Table 1）meeting the requirement as being part of the inverted repeats（see Figure 3）.
Figure 4 Localization of the genes for 16S rRNA and the large subunit（LS）of RuBPCase on the BamHI and SmaI fragments of N.otophora chloroplast genome.The probe for the LS is a hybrid plasmid from the clone PJEA 4 which consists of pBR322 and a 2.0 kb of spinach chloroplast DNA fragment containing the LS.After nick-translation the probe was hybridized to the BamHI and SmaI fragments.The autoradiograph showed two labeled BamHI［（a）1］and one SmaI［（a）2］fragments，corresponding to BamHI fragments 20 and 24，and SmaI fragment 1.The probe for 16S rRNA was EcoRI fragment 8 of N.tabacum ct-DNA.Both BamHI fragment 11 and SmaI fragment 4 were labeled［（b）1 and 2，（c）1 and 2］(https://www.daowen.com)
In a similar manner，the BamHI fragments containing the gene for LS of RuBPCase was also identified using spinach RuBPCase LS gene as probe.The LS gene of N.otophora ct-DNA containing a single BamHI restriction site is located on fragments B20 and B24 as determined by hybridization（see Figure 4）.These fragments correspond to SmaI fragments 1 and EcoRI 4 fragment（see Figure 1 and Figure 3）.
