Bacteria use small RNAs to respond to changes in temperature, nutrients, acidity, physical stress—the works. Sometimes, the chemical letters that make up RNAs like these are adorned with extra atoms. These add-ons are like molecular diacritics: umlauts, acutes, tildes... In both biological and linguistic settings, the little modifications alter the letter’s meaning. Sometimes they prevent mix-ups, or offer a bit of much-needed ambiguity, or enable entirely new words to be spliced into existence.

 How do these modifications affect those important RNAs that bacteria need to survive?

Enter Vibrio fischeri. This is a bacterium that glows in the dark, and it has a special partnership with the bobtail squid. This nocturnal little squid (very little squid! Below is a photo of a full-grown adult) has a light organ, a tiny butterfly-shaped home for its bacterial partners. It’s a full house—adult squids have around ten billion bacterial cells inside. The squid provides its bacteria with shelter and nutrients, and in return, the bacteria produce bioluminescence that the squid can fine-tune as it searches for prey, using the downcast light to cancel out its moonlit shadow.

With this bioluminescent bacterium, I am exploring how little chemical modifications on its RNAs affect both it and its squid host.

Squiddo!

Photo courtesy of Margaret McFall-Ngai and Edward Ruby