Guanine comes from biochemistry. It is a compound that occurs in guano and fish scales, and is one of the four constituent bases of nucleic acids. A purine derivative, it is paired with cytosine in double-stranded DNA.
In 2380, Admiral John Hayes was aboard the USS Guanine when there was a malfunction during the ship's Quantum slipstream drive testing trials. Commander Taylor Ferguson, the ship's executive officer, Admiral Hayes, and the entire engineering crew died in the explosion. ("The Teacher")