Abstract
A composite map representing a single ribosomal DNA repeat unit of the house cricket, Acheta domesticus, was constructed from overlapping cloned fragments. Sites in the repeat unit for nine restriction enzymes were mapped. R-loop mapping of sequences coding for 18 S and 28 S RNA demonstrates that the 58-kb ribosomal DNA repeat unit contains a novel-sized internal transcribed spacer of 8.4 kb. The existence of this large spacer was confirmed in genomic DNA, most if not all of the genomic repeat units containing such a spacer. A 15- to 17-kb ribosomal RNA precursor transcript is synthesized as predicted on the basis of the size of the internal transcribed spacer. The 5.8 S RNA gene is localized to a 1-kb sequence immediately 5′ to the 28 S gene. The coding regions examined contain no intervening sequences analogous to those described within ribosomal DNA of other eukaryotes. Only 11% of the repeat unit codes for mature ribosomal RNA, while the remainder is nontranscribed (71%) and transcribed (18%) spacer DNA.
Original language | English (US) |
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Pages (from-to) | 345-358 |
Number of pages | 14 |
Journal | Biochemical Genetics |
Volume | 25 |
Issue number | 5-6 |
DOIs | |
State | Published - Jun 1 1987 |
Externally published | Yes |
Keywords
- nontranscribed spacer
- ribosomal DNA
- ribosomal RNA
- transcribed spacer
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Biochemistry
- Molecular Biology
- Genetics