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Thursday, September 23, 2010

Friday Photo Shoot Out: Hot & Cold

This is a thermocycler. It gets pretty hot for 20 seconds, then cooler but uncomfortably warm for 20 seconds, and then hot again but not so much as at first for 20 seconds to several minutes, depending on what you want. Then it goes through all those steps again, 25 to 35 times. If you started with some DNA and a couple of primers that face each other in the DNA, at the end you've got a jillion copies of whatever is between the primers. In my lab we go sequence that and find out if there's a mutation that might predispose to cancer.
Graduate students used to sit in front of collections of water baths for hours on end, transferring tubes from one to another, but now we have thermocycler machines that do all that for us. Thank goodness. This particular machine will do 384 samples for us in about 2 hours, which is about a quarter of the lab's capacity. Next year we should double that.
And, yeah, the four blocks all have names. We keep track of which block does which experiment, and the Tetrad has Joe, Jack, Avery and Tex. It's more fun than blocks 13, 14, 15 and 16 and easier to remember.


Out back, between the vast array of trash bins (paper & cardboard recycling, plastic recycling, kitchen trash and regular trash, plus a huge bin for the construction zone) and the auxiliary parking (no, no! fire truck access lane! though there is always a car or two or three there) is the tank farm. Nitrogen to the left, oxygen on the right.

There's a collection of small N2 tanks in our cold room, which we use for temporary storage and to take to different hospitals to collect surgical specimens for instant freezing. In a different building now we have four or five huge tanks for permanent storage.
Liquid N2 is about -196°C, and produces clouds of vapor as it boils whenever anything warmer approaches. Dunking a real rat in it would not be very nice. Stuffed rats hold up pretty well. If you slosh it on the floor, here on the tile you might crack some, but in the main lab (where we actually manipulate it, because the cold room is too small to be properly ventilated) you can see where we've spilled because it cracks the linoleum terribly.
Wearing these huge gloves isn't practical all the time. Just try to hold a tube half an inch by one inch with these things on. So we use big tweezers. And sometimes our fingers, which doesn't do much harm as long as you let go very quickly. Otherwise watch out for the freezer burn.

One of these rats is very, very cold.
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There was an episode of NCSI on the other day, where the murder victim had been killed by forced ingestion of liquid nitrogen. The scientific team supposedly found traces of the liquid N2 in the thermos used to transport it. Nonsense! When it warms up, the liquid simply becomes nitrogen gas, which makes up 78 % of normal air. There are no 'traces' to be found. I hate it when science-dependent shows do bad science.
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11 comments:

Niamh B said...

I love putting rubber gloves in liquid N2, they crumble like leaves.
It doesn't take much to amuse me

Bagman and Butler said...

Fascinating! I always wondered what you actually did. You use machines to torture DNA while play with dunking stuffed rats in liquid Nitrogen. Aren't grants fun? There's probably a paper coming out on The Effect of Liquid Nitrogen in Prevention of Cancer in Stuffed Rats. Great shoot! Educational and Fun. If you'd been my professor, I would have switched majors.

jabblog said...

I hope you manage to avoid the burns - at least most of the time. Sweet rats ;-)

Jama said...

Interesting place!

Titus said...

Nooooooooo!

The rats are stuffed...?

Pauline said...

Fantastic shoot-out, Nan. Your every day stuff is "out of the box" to the rest of us. The frozen rat shot is great. And I hate it when a speciality programme gets it wrong, too. My pet hate is newsreaders who use incorrect grammar. Today I heard recreate used when it should have been re-create and the item made no sense.

Sarah said...

Oh wow what a cool perpective on this...I love it..even the frozen rats...LOL!! Wonderful shootout!!!
Hugs, Sarah

Ann said...

Do they freeze human eggs the same way.

I don't like rats, but I bet your rats hate you after freezing them like that.

In the eye of the beholder said...

You most have a very interesting career.

Doreen said...

glad that was a stuffed rat. the one steaming is the cold on. we have nitrogen tanks at work. I really liked all the info and pics. great shoot out and love the new header shot!!

EastwoodDC said...

It can truly be said that your rats are very cool. ;-)