13. “I don’t believe all those colonies represent retrotransposition events.”

In 1993, Dombroski isolated the other two full-length L1s that hybridized with the JH-27 oligomer from the phage library of JH-27’s mother. Both of these elements were Ta subfamily members and had intact ORFs. However, they each had many nucleotide differences (about 1 in every 200) from L1.2B, the JH-27 precursor L1. These latest potentially active L1s were located on different chromosomes and were also polymorphic as to presence in human genomes. Some individuals carried them, while others did not (Dombroski et al., 1993). All of this was fine, but the field still badly needed a cell culture assay for retrotransposition. Enter John Moran.

John Moran was a tall, gregarious ...

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