Taming of transposable elements by homology-dependent gene silencing

摘要: Transposable elements can invade virgin genomes within a few generations, after which the are 'tamed' and retain only limited transpositional activity. Introduction of I element, transposon similar to mammalian LINE elements, into Drosophila melanogaster devoid such initially results in high-frequency transposition incoming transposon, high mutation rate, chromosomal nondisjunction female sterility, syndrome referred as hybrid dysgenesis1 (for review, see refs 2, 3, 4); related has also been described mammals5. High-frequency is transient, number reaches finite value ceases approximately ten generations6,7. It proposed that encode factor negatively regulates their own transcription, but evidence for mechanism lacking8. Using dysgenesis 1,2,3,4 model, we show here activity element be repressed by prior introduction transgenes expressing small internal region element. This autoregulation presents features characteristic homology-dependent gene silencing, process known cosuppression9,10,11,12,13,14,15. Repression does not require any translatable sequence, its severity correlates with transgene copy it develops generation-dependent manner via germline transmission silencing effector females only. These demonstrate transposable prone tamed may have emerged during course evolution specific defense against these elements.