One duty that consumed several hours of my time this afternoon was taking care of frogs, fish, and flies before I take off for a week. In particular, I had to set up a whole bunch of fly stocks that I'll be using this spring in my genetics course. This particular bottle was unintentionally appropriate for the season:

Get it? ho/ho? Like Santa, only it's a bottle of flies carrying the ho allele? I know, lame fly genetics humor…

That's a bottle of fly medium containing some mutant flies. They are called heldout, or ho for short, also known as dpp^d-ho. This is an allele of the decapentaplegic gene, an important molecule in the signalling pathway that defines dorso-ventral polarity in Drosophila.

As a curious coincidence, I noticed that the heldout mutation was discovered by Edward Novitski—I knew Ed Novitski. I was his TA back at Oregon way back when.