| Budget Amount *help |
¥5,200,000 (Direct Cost: ¥5,200,000)
Fiscal Year 1989: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1988: ¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1987: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
The Drosophila transposable element copia is a retrotransposon that is structurally similar to retroviral proviruses. It is 5-kilobase(kb) length and terminates with 276-base pairs(bp) long terminal repeats (LTRs). It seems that copia elements transpose through an RNA intermediate from structural analysis and some other information. To date, however, there is no direct evidence to show it. In Drosophila cultured cells, we have previously found that major transcripts of copia elements are 5-kb RNA and 2-kb RNA which is generated through splicing. If copia elements really transpose through the RNA intermediate in Drosophila cultured cells, we can expect two different kinds of copia DNAs; one for a 5-kb copia DNA which is generated by the 5-kb RNA and the other for a 2-kb copia DNA which is generated by the spliced 2-kb RNA. The 5-kb copia DNA is the same as sequence, of copia elements before transpose, but the 2-kb copia DNA is not. To demonstrate that copia elements transpose through the RNA, intermediate, I noticed the 2-kb copia DNA and analyzed the existence of it. Using the polymerase chain reaction method, the spliced sequence identified on genome of Drosophila cultured cells containing copia elements, and of cultured cells made by introducing only 5-kb copia DNA into copia free Drosophila cell line (D.hydei ). Moreover, I have isolated a DNA fragment containing the spliced sequence. Nucleotide sequence analysis of the isolated DNA fragments showed existence of 2-kb copia DNA which has no region corresponding to the spliced out fragment. It is terminates with 276-bp LTRs whose nucleotide sequences are the same as LTR sequence of the 5-kb copia DNA. Host direct repeats of 5-bp located on outsides of both the LTRs. These results strongly suggested that copia elements transpose through the RNA intermediate.
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