I get emails: frozen edition!

Here’s another question I received recently via Slack:

Them: We have ~120 [lizard] heads that we removed post euthanasia from captive born offspring of 4 different populations... The animals were euthanised in liquid nitrogen and then the heads were persevered in 10%NBF [neutral buffered formalin] 24hrs, then 70% EtoH [ethanol]. I am using the heads for scale counts.... However, post that I was wondering if there is the possible application of looking at their brain morphology? I have had a brief look at the literature, and suspect that we probably haven’t preserved them in an appropriate manner. Similarly, I think the liquid nitrogen euthanasia may cause some issues. I thought I’d ask for your thoughts as it seems like a waste if we could apply it to brain morphology questions. … I thought there may be question around relative sizes of different regions of the brain, … etc. This is all out of my wheelhouse so I could be totally off on this one! Any thoughts on if there is anything that can be done with them?

Me: Does "euthanized in liquid nitrogen" involve freezing them [Edit: This seems obvious in retrospect, but I thought it might have been via asphyxiation]? If not it might be worth a go. The 70% ethanol is not great but 24 hrs in neutral buffered formalin might be enough to prevent the EtOH-induced shrinkage, and 70% EtOH is better than 100%... It might be worth a go for MRI but I don't think you're going to have any success with histological methods after the EtOH. 

Them: The whole lizard was frozen solid in liquid N.

Me: Ok then no chance.

So this is probably the most common problem I encounter with offers of brains to study: the brains on offer have been frozen. If you think there is any chance that you’ll want to use a brain for research DO NOT FREEZE IT. Put the whole head in a sealed, humid container in the fridge, and contact your nearest local neuroscientist immediately. If you have access to formalin, put the head in formalin for 24 hours and then, again if you have access, put it in saline until you can get it to a neuroscientist. If you don’t have access to saline, still remove the head from the formalin, rinse it in water, and store it in a sealed container wrapped in paper towel moistened with water.

I remembered to post this today because of this tweet. It seems like this freezing thing is not just a me-problem!

Andrew’s Twitter is here if you have any (never frozen) extra bird brains.

If you have any comments or suggestions on what I’ve said here, please don’t hesitate to get in touch. I’d love to hear from you.

And if you have an extra bird brain lying around, please get in touch with Andrew, and DON’T FREEZE THEM FIRST!

Beneath the Surface

I found out through a tweet that my favourite travel guide company was having a travel writing competition, and that entries were due in 24 hours. Even though I was (very) late, I had a spark of inspiration and wrote something that day. The theme was “beneath the surface” and the shortlisted entries were just announced today. Even though my story didn’t get selected as a finalist I still think it’s not half bad and I thought I’d post it here anyway.

Walking under Memphis

Although I was humming its most famous tune, I was not in Memphis to see any of its most famous sights. I was here to see the inside of a lizard’s brain.

I had never been to Memphis before, and as I was making my way through the airport I couldn’t get “Walking in Memphis” out of my head. I have always loved the song, and this was the first time I could sing it to myself while actually walking in Memphis. For weeks I had been anticipating my trip to this city steeped in American mythology, on the banks of America’s grandest river, the Mississippi. I was curious about Memphis’s famous attractions: Bourbon Street, Graceland, The Pyramid. But mostly I was eager to slice open the brain of a lizard and peer down at what was inside.

The following morning I arrived bright and early at Memphis’s Rhodes College and was immediately struck by the beauty of the campus. Its Old Gothic sandstone buildings are impressively imposing and give the campus an air of intellectual gravity – which I suspect was the architect’s intention. The fact that it was still only March meant that the trees were bare and the grass was dead, giving me a sense of quiet foreboding that was not helped by the fact the campus was deserted, it not yet being 7am. This was the only time my busy host, a Rhodes professor, had available to meet with me, so I hurried through the campus.

A sandstone wall at Rhodes College, Memphis Tennessee

I was stopped dead in my tracks when I arrived at my host’s building, or, rather, the location where his building should have been. What I found was not a beautiful structure made of multicolour sandstone, but an empty courtyard.

The courtyard where the building I was looking for should have been.

I searched the courtyard’s perimeter and found a non-descript set of damp concrete stairs that lead underground before ending abruptly at a concrete wall. As I descended the steps I noticed a door to the right, without any indication as to where it might lead.

The nondescript concrete steps leading underground.

To my surprise the door was unlocked, and opening it revealed a poorly-lit, cavernous hallway. In display cases along the walls taxidermied animals stared at me through their glassy eyes, but otherwise it was completely deserted. I wandered the halls, my footsteps making uncomfortably loud echoes, searching darkened offices and research labs for signs of life. Eventually I noticed one lab with a light on, and to my relief found my host.

I had ventured into this underground lair of a research facility to learn a new technique for studying the brains of lizards, which I use to learn about how evolution shapes brains through natural selection. The professor I was visiting is one of the world’s foremost experts on the topic. The technique is called immunohistochemistry and uses extracts from the blood of animals, in this case goats, donkeys, and rabbits, to study how certain proteins are distributed inside a brain. It’s rather like attending a one-day cooking class to learn a new cooking technique, except the ingredients are closer to the components of a witch’s brew than a crème brûlée.

I spent that day in the underground laboratory learning how to carefully slice lizard brain tissue, combine the slices with solutions derived from the blood of animals, stir the mixture thoroughly, and then mount the slices carefully on microscope slides. It felt appropriate to be learning this in a lair under a city famous for Hoodoo mysticism. Of course at the end of the process we did not consume our concoction, but rather examined the brain slices under a microscope. And instead of reciting incantations we discussed how to identify brain cells that produce the neurotransmitters oxytocin and vasopressin. In my mind, the whole experience emphasized how much modern science can have the feel of witchcraft when you take a step back.

Some slices from the brain of a lizard incubating in a solution derived from rabbit and donkey blood.

My host, the lizard brain expert, found nothing particularly unusual about his lab, only lamenting the lack of windows. But as I was leaving campus that evening, I was thinking about how a large scientific research facility was present on this campus yet almost completely undetectable, and I wondered what else an old, mystic city like Memphis might be hiding below its surface.