CORRELATION BETWEEN THE NUMBER OF OCCUPIE D SITES, TRANSCRIPT LEVELS AND TRANSPOSITION RATE OF RETROTRANSPOSON IN COPIA DROSOPHILA-MELANOGASTER

Numbers of copia transcripts in testes of flies from five Drosophila m elanogaster lines were compared by means of Northern blot hybridizatio n. Four of these lines were closely related differing only by transpos ition rates and the number of copia sites in the genome. The fifth lin e, which was not related to the others, was characterized by lack of t ranspositions and the lowest copia copy number. Positive correlation b etween total copia transcript level and its copy number and transposit ion rate was observed. Therefore, transcription rate of copia retrotra nsposon in testes is largely controlled by the level of its transcript ion, which, in turn, is regulated by the number of retrotransposon cop ies in the genome. These data contradict the hypothesis on self-regula tion of retrotransposon copy number in the genome.