Sir

In his otherwise excellent News and Views “The grand assault” (Nature 419, 493–494; 2002), Russell F. Doolittle writes: “Eukaryotes can be loosely defined as organisms whose cells have nuclei and cytoskeletons, distinguishing them from the Bacteria and the Archaea, neither of which has introns in their coding sequences.”

Bacteria and the phage that infect them do contain introns in their genomes. The first example of an intron in a bacterial system was found in the thymidylate synthase gene of bacteriophage T4 (F. K. Chu, G. F. Maley, F. Maley and M. Belfort Proc. Natl Acad. Sci. USA 81, 3049–3053; 1984) — the last author being my mother. Since then, hundreds of introns have been found in archaea, bacteria and their phage.

It has been a long time since I uttered these words, but I couldn't be more proud to say: “Mommy told me so.”