Tissue-specificity of 412 retrotransposon expression in Drosophila simulans and D. melanogaster.

We analyse the expression of the retrotransposon 412 in the soma, testes, and ovaries in populations of Drosophila simulans and D. melanogaster, using RT-PCR and in situ hybridization. We find that expression of 412 is highly variable in the soma, confirming previous findings based on Northern blots. No 412RNA is detected in the ovaries by either in situ hybridization or RT-PCR, in any population of either species. Transcripts are, however, detected in the male germline, which show a very characteristic spatial pattern of 412 expression in primary spermatocytes. There is no relationship between expression of the 412 element in the soma and in the testes in the populations. These findings show that the expression of 412 is independently regulated in the soma and the testes, and this raises the question of the real influence of the somatic transcripts on the organism and on the transposition rate.