Isolation of markers from recently transposed LINE-1 retrotransposons.

Many previous techniques for the isolation of endogenous retroelements such as LINE-1 retrotransposons have produced major sampling bias or required laborious procedures. These problems led to the isolation of only older elements in some cases. In other cases, specialized systems were required for the isolation of recently transposed elements. We report here a system for the easy isolation of markers from a wide range of LINE-1 elements and the screening of recently transposed elements from that population. This is accomplished by the use of PCR with degenerate primers specific for conserved regions of the reverse transcriptase gene, a modified screening vector, and a refined blue/white colony assay that screens for amplified DNA containing open reading frames. This method should be applicable to searches for endogenous retroviruses.