Isolation of Markers from Recently Transposed LINE-1 Retrotransposons

Many previous techniques for the isol a tion of endogenous retroelements such a s LINE-1 retrotransposons have produce d major sampling bias or required laboriou s procedures. These problems led to the isol a tion of only older elements in some cases. I n other cases, specialized systems were r e quired for the isolation of recently tran s posed elements. We report here a system fo r the easy isolation of markers from a wid e range of LINE-1 elements and the screenin g of recently transposed elements from tha t population. This is accomplished by the us e of PCR with degenerate primers specific fo r conserved regions of the reverse transcri p tase gene, a modified screening vector, and a refined blue/white colony assay that screen s for amplified DNA containing open readin g frames. This method should be applicable t o searches for endogenous retroviruses .