Tuesday, January 25, 2011

OMG science people can be cool too!!!

Recently our wonderful PI, Amy MacQueen, (cautiously) emailed us this FANTASTIC video which is parody of Lady Gaga's "Bad Romance", entitled "Bad Project".


Yes, I know, it's amazing.
According to examiner.com the Zheng Lab is part of the Pathology and Immunology department at the Baylor College of Medicine in Houston Texas. The school is one of the only private medical schools in the greater southwest and was ranked in the top 25 schools of 2011 in the "US News & World Report".
(This is the specific link: http://www.examiner.com/dance-in-los-angeles/lady-gaga-science-geeks-parody-bad-romance-video)

According to their website, the Zheng lab is:

"studying the molecular and cellular bases for the fundamental properties of an effective immune response, such as specificity, affinity, and memory using the techniques of cell and molecular biology, and in vitro and in vivo models of immune responses.

Also, we are applying similar approaches to understand the pathology of aging and autoimmune diseases."

Their current projects focuses on antigen driven lymphocyte differentiation, Germinal center biology, Immunosenescence and Autoimmunity.


According to the first site, the woman who is impersonating Lady Gaga is Mary Wiese, and soo of course I tried to find a paper written by her and the lab. And I did! I have included a link to the one that I found below. I will share more if I find more.

Anyway, I know this post mostly consisted of information from other websites (that I'm sure you all have already seen) but I thought it would be a good opportunity to come back to one of the original intentions of the blog which was to talk about the people involved in science today and even touch upon aspects of science culture when given the opportunity.
Scientists can be witty and creative in ways that people don't always expect!

Tuesday, January 18, 2011

Because my creativity is severly lacking

Ihave YET ANOTHER post, courtesy of my friend Monica Vitti, who is amazing, shared this with me via the great and all-powerful facebook. I felt that I needed to pass this along. Thank you Kevin Van Aelst for being much more creative than I am and appreciating the beauty of science via food. This is the website that is the source of all this creativity: http://www.kevinvanaelst.com/art.html

Lab Love,

Thursday, November 11, 2010

It's been a while!!!!

So it has been quite a while since anyone has posted on our lovely blog and I refuse to let it die SOOO when a friend posted this on my facebook wall, I thought, what better place to share this than on our lab blog?!? LOLZZZ!!! Even though the definition sounds more like meowtosis.

I also thought that I would share the wonderful discovery that I made; Do you ever have SO MANY ARTICLES to read??? of course you do. Do you ever have SO MANY PLATES to dissect??? Of course you do! Did you know that in Adobe Reader, you have the option of having your article read out loud to you? Well you do! all you have to do is go to 'view', 'read out loud', 'activate read out loud' and you can have it read the page or whole article to you. You can even change the pitch and speed of the voice. It's better than listening to music. It will also kindly try to read the websites, sources and even sometimes figures in the papers to be read out loud. My point being that it's not great but it can be helpful so I thought I would share.

Lab Love,

Wednesday, August 4, 2010

Today I went hunting for Falcon Tube

and found this instead...

The various constituents of Olson lab were nowhere to be found. I suspect they are inside this machine.

Tuesday, August 3, 2010

Fun Fact of the Evening

Or morning, as the case may be.

I was reading about different types of blotting and the article (okay I admit it, it was the Wikipedia entry for Eastern blotting) had a fun timeline of all the witty scientists who have invented new types of blotting and carried on the tradition/joke of cardinal-direction-related names. (Southern blotting came first, and then Western, Northern, Southern, and a whole slew of sub-directions followed.)

I got very excited when I saw this one:

"(1984) Middle Eastern blotting has been described as a blot of polyA RNA (resolved by agarose) which is then immobilized. The immobilized RNA is then probed using DNA."

MIDDLE EASTERN BLOTTING!!!!! Hailing from the Middle East myself, this pleased me immensely.

From Sarah Moustafa on Picasa
The Middle East, minus the blotting.

And the paper that presented Middle Eastern blotting (mad props!), courtesy of PubMed:

Monday, August 2, 2010

A Closer Look: TCA Protein Preps

Last week, Amy (our sensational PI) and Esther (who, along with Tati and Rozi, has now absconded for home, leaving me to fend for myself in Mac Lab) came to me with a quandary-slash-question and I was pleased when I realized that, with the help of some chemical structures and pKa values, I could answer it! Amy was super excited at the structures that I drew on our whiteboard and suggested of her OWN volition (FOR ONCE) that I blog about it! So here, for you now, is my own understanding of how TCA protein preps work on the chemical level.

Some background. Esther has spent the summer working with proteins (whereas I have been focusing on genetics and cytology, and Rozi and Tati's project involved a genetic screen) - specifically, she was investigating whether proteins involved in regulation of the assembly of the synaptonemal complex (SC) in meiotic chromosomes are themselves regulated by posttranslational modifications that are dependent on recombination. Yes, that is a mouthful - to rephrase it, what she would like to find out is Spo11, the major protein player in recombination that catalyzes double-stranded breaks in DNA to initiate recombination events, also has an effect on the regulation of SC-assembling proteins by having upstream control over if and when these proteins are modified (i.e. by SUMOylation), if at all, as the modification of these proteins may be dependent on the occurrence of recombination events. So for example, if the SPO11 gene was knocked out in a strain, would there be any effect on the physical state (covalent modifications) of SC-assembling proteins - and if so, would this suggest that a lack of recombination sites on the chromosomes led to the SC-assembling-protein posttranslational modification pathway not being activated?

To answer these questions she was using Western blotting and, EXCITINGLY, 2D gel electrophoresis to basically check out the size of different SC-related proteins - Fpr3, Zip2, Zip3, Zip4, and Rrd1 - in both SPO11+ and Δspo11 backgrounds to see if there was any difference in size of the SC proteins in the two different backgrounds. BUT OF COURSE, before she could run these proteins out on gels, she had to isolate them from cells of her strains. And how did she do that? BY TCA PROTEIN PRECIPITATION. This is where I come in.

The TCA protein prep protocol is a relatively straightforward one - it involves variations on the basic theme of pelleting yeast cells, vortexing the pellet with TCA and glass beads to lyse the cells and release the protein, and then washing with a basic resuspension solvent to force the total cell protein out of solution as a pellet. Cool, right? But what she wanted to know was HOW adding some TCA to cells actually precipitated ALL of the protein in the cell, with no regard to specificity or anything. She had read somewhere that "hydrophobic aggregation" was involved. So I looked up the structure and pKa of TCA, and a lightbulb TOTALLY went off.

TCA is trichloroacetic acid, a derivative of acetic acid:

(Yes, this post, like the zygote post, is going to be illustrated with my superlative Paint skills. At first I was using ChemSketch, a really awesome molecule-drawing freeware program from ADC/Labs that you can get here, but then I got tired of it because the molecules all looked so uniform. I think molecules should have PERSONALITY.)

In aqueous solution, TCA dissociates into its conjugate base plus hydrogen ions:

Note the pKa, 0.77. That is VERY LOW. As you will recall from biochem, orgo, or wherever you learned about the lovely world of dissociation reactions, pKa is a measure of the acidity of a molecule - more specifically, the equilibrium constant for the dissociation reaction, and a measure of a molecule's affinity for its acidic proton when in aqueous solution (water). Since pKa is a measure of the RATE of the dissociation, and in general, the rate, K, of a reaction is given by-

K = [reactants]/[products]

reactions with a very high K (and in turn a very low pK, because pK = 10^(-K)) have a very HIGH ratio of reactants to products in solution. In our case, this means that in solution, virtually all of the TCA has dissociated into protons and conjugate base, because the proton so readily dissociates from the hydroxyl group.

(Of course, we could take this down even another level and point out that TCA has such a low pKa because of the enormous electronegativity of the halogenated end of the molecule - chlorine is the second most electronegative atom out-electronegated only by fluorine, and THREE chlorines all on one end of the molecule STRONGLY polarizes the electrons in the molecule toward that end - this enormous pull for the electrons away from the hydroxyl group means that there is a very small net electron density on the hydroxyl group, not leaving much for the proton to "grip" onto so it pops off quite easily.)

But of course, I lied to you in that drawing above. Free H+ atoms NEVER exist in solution. They ALWAYS exist coordinated to water molecules by hydrogen bonds. So really, the above reaction looks like this:

Notice anything? Given the extremely low pKa of TCA, its rapid dissociation means that practically ALL of the water molecules in solution will be "occupied" by existing as hydronium (H3O+) ions!

Now let's zoom out to Esther's experiment. This is why I love biochem.

Esther's protocol called for adding TCA and glass beads to a cell suspension, vortexing vigorously, centrifuging and collecting the supernatant, and then pelleting out the protein from the super by resuspending in Tris base. NOW WE KNOW how the TCA makes the protein fall out of solution! Do you see it yet? (The glass beads and vortexing were simply physical trauma to the cells to lyse them and release the protein and other cell contents.)

When you add TCA to an aqueous solution, it dissociates IMMEDIATELY and the ENORMOUS concentration of protons intercalate with the water molecules, effectively blocking them from solubilizing the cellular protein (which is mostly hydrophilic, as most cellular proteins have at least one hydrophilic region). Since the TCA outcompetes the protein for hydrogen-bonding with water, the proteins have nothing to do but aggregate with themselves and fall out of solution as hydrophobic aggregations.

This picture is actually most accurate because each water molecule is hydrogen-bonding with two protons - because the oxygen in water has two lone pairs, each of which can coordinate one proton. Then when you spin this whole mixture at high RPMs, cell debris (like the cell wall and membrane and organelles) and protein fall completely out of solution, while water keeps the TCA busy (or vice versa, as the case may be) in the aqueous layer. Tossing out the aqueous layer yields a pellet containing all of your cellular protein! The pellet also contains unwanted cell debris, so a wash and spin in a very basic resuspension solution (i.e. Tris base) again forces the cell debris (which are not that polar) out of solution, FINALLY yielding a solution of all the cellular proteins.

Really cool chemistry behind a useful, (seemingly) straightforward protocol. :)