AMBER - OCHRE - OPAL EXPLANATION PLEASE!!!

[mb_nelson at mbcl.rutgers.edu]

does anybody know why the names amber, ochre, and opal were given to the
stop codons?? I read in a text book that it was because of some 
laboratory joke but the book didn't say what the joke was.  
Please send responses to my e-mail address:  mb_nelson at biovax.rutgers.edu
thanks!   susan
WAIT!!! I wrote the wrong e-mail address. Th e correct one is :
mb_nelson at mbcl.rutgers.edu  thanks