Powell Lab: Studying innate immunity in c. elegans

Hello all!

My name is Leah Grandi, and I am the only member of the Powell lab staying this summer. My usual labmates, Joe Robinson and Jimmy Nguyen, are off working at Pitt and Johns Hopkins (aka. places that probably have more windows than our lab here). As for myself, I remain in McCreary 208, with the dull hum of the incubators and freezers as my constant companions.

Figure 1. Our lab family! From left to right, we have myself, Dr. Powell (also known as Glorious Leader or J. Pow), Joe and Jimmy.

Figure 1. Our lab family! From left to right, we have myself, Dr. Powell (also known as Glorious Leader or J. Pow), Joe and Jimmy.

We are molecular geneticists who choose to research with worms. Now, these aren’t the earthworms that you probably thought of initially. These worms are microscopic nematodes known as Caenorhabditis elegans (C. elegans for short). And we think they are pretty cute.

Figure 2. A normal agar plate of C. elegans eating some delicious E. coli. Bon appetit! Image from: http://molecular-ethology.biochem.s.u-tokyo.ac.jp/g1/wt%20on%20plate.jpg

Figure 2. A normal agar plate of C. elegans eating some delicious E. coli. Bon appetit!
Image from: http://molecular-ethology.biochem.s.u-tokyo.ac.jp/g1/wt%20on%20plate.jpg

Our lab uses C. elegans to research the immune system. We are primarily interested in the innate immune system, the part of your body’s defense mechanism responsible for fever and inflammation. One of the most interesting things about the innate immune system to us is the conservation of this system in all animals. That means that this adorable microscopic worm and we complex humans have similar ways of responding to infections. And we think that’s pretty cool.

To test the immune system, we infect our worms with Pseudomonas aeruginosa, a particularly nasty bacteria that is a common cause of hospital acquired infections. Our protein of interest is called FSHR-1, and it has been shown many times to be involved in innate immunity. Worms that do not produce the protein FSHR-1 are immunocompromised compared to worms that do produce FSHR-1.

Another lab that we collaborate with identified a particular toxin that P. aeruginosa secretes called Exotoxin A. This lab also identified two genes that were induced in the worm upon infection with normal bacteria (Escherichia coli, C. elegans’ food) that have been genetically engineered to secrete Exotoxin A. This induction was observed to occur in an FSHR-1 dependent manner. Naturally, we are interested in these genes and want to learn more about them. We have a pretty cool technique to do just that.

One thing that every worm scientist loves to do is make our worms glow. To do this, we fuse the 3’ and 5’ DNA regulatory regions of these genes to the gene for Green Fluorescent Protein (GFP). When our DNA construct is injected into a worm, the worms’ cells will transcribe and translate GFP every time the cell transcribes and translates the gene of interest. We can see the GFP by using a very fancy and expensive microscope (also unfortunately located in a room without windows). The worms that we create are a very helpful genetic tool for visualizing the expression of the gene of interest.

Figure 3. An excerpt from my Celebration 2014 poster, outlining the genetic process of creating a reporter construct.

Figure 3. An excerpt from my Celebration 2014 poster, outlining the genetic process of creating a reporter construct.

Last semester, I worked on creating the DNA constructs for two genes of interest. Dr. Powell managed to inject one of these constructs into a worm. When we infected these worms with P. aeruginosa, we saw some small green spots in the worms’ tail that weren’t there when the worm was eating E. coli. This was very exciting for us, because it means that our reporter works!

However, when the DNA construct is first injected it remains outside of the genome. This means it’s just floating around in the nucleus, and isn’t always transmitted to the next generation because it’s not integrated into any of the worms’ chromosomes. My current project has been to integrate the DNA construct into the worms’ genomes. To do this, I expose the worms to radiation and hope that the DNA gets knocked into one of the chromosomes of that worm’s offspring. So far, I haven’t found an integrated worm yet, but the search is still ongoing.

That’s all for my project! Also while in the lab this summer, I have been doing some other projects, such as a genetic cross for Jimmy and more reporter inductions for Joe.

Please, if you have time and would like to see some cool worms, stop by McCreary 208. I welcome any and all company.

Sincerely,

An extrovert who is working all alone this summer

 

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s