Figure 2.

Alu mobilization assays. (A) Alu retrotransposition assay (Dewannieux et al. 2003). (1) Alus were cloned into a test plasmid containing the 7SL polIII enhancer and a neo retrotransposition selection cassette. The cassette contains a neo G418 resistance gene that is interrupted by the self-splicing tetrahymena intron. (2) Upon polIII transcription, the tetrahymena intron is spliced out. (3) When cotransfected with L1 ORF2p, Alu RNAs are reverse transcribed along with the neo gene, and (4) integrated into the genome, conferring G418 resistance. (5) After a 2-wk treatment with G418, resistant colonies are stained, photographed, and counted. (B) Assay results for a sample of genomic AluS elements. Activities are given relative to AluYa5 activity (100%) within each assay. Each horizontal bar indicates the mean of multiple independent assays (dots). Each dot represents the average of a single (triplicate) experiment. Gray vertical bars represent 95% confidence intervals. The percent consensus identity is indicated below each element. (C) AluY subfamily results. (D) Mobilization activities of known polymorphic AluY elements and a polymorphic AluSx. The dbSNP ss numbers are listed for each. (E) Resurrected AluJo and Sx elements. The mobilization results for artificially constructed 100% consensus AluSx and AluJo elements are compared with a highly conserved (but inactive) genomic AluJo (Jo_h10.1).