Amoeba hugs are often deadly, and sometimes they set your career

This post is written by NCAT faculty Misty Thomas

My passion for Microbiology first started when I was in my undergraduate microbiology class at the Collège Universitaire de St. Boniface, in Winnipeg, Manitoba, Canada. I’m sure it was a cold day, as it almost always is in Winnipeg, but we were feeding amoebas small planktonic crustaceans called daphnia under the microscope. I watched the amoebas’ pseudopods (blobby arms) try to grab the daphnia to eat it three times, the daphnia kept teasing the amoeba until finally, on the fourth try, the daphnia met its death. After being engulfed, the amoebas’ digestive enzymes (internal fork and knife) came out and obliterated the daphnia. If you want a view of what I saw, here is a YouTube video of an amoeba eating two paramecia (, let me know what you think! What I learned from this moment on was that I was destined for a life in Microbiology. When I first started my undergraduate career, my plan was to be a high school chemistry and physics teacher, but after becoming more interested in Microbiology (and reading the Hot Zone), I ended up double majoring in Microbiology and Biochemistry. Then, in my second year, I went to a seminar which discussed alternative careers to medicine (because that apparently is where all the other science majors want to go) and I was then convinced I was going to graduate school.

With not a minute of real research experience, I originally had a hard time finding an advisor for grad school, and was told directly that I didn’t have what it took to be successful in a PhD program. I persisted and found an advisor and started graduate school directly after undergrad in the department of Microbiology at the University of Manitoba (also in Winterpeg). Here my advisor Dr. Brian Mark introduced me to research through studying proteins involved in antibiotic resistance, a perfect combo for a micro/biochem major. The goal of my PhD work was to study proteins involved in making the bacterial cells wall (a hard case-like structure around the cell that gives it strength and protection) and find ways to stop them and as a result kill the bacteria. Since humans don’t have cell walls we can design drugs that target the bacteria without causing harm to us, this is knowns as selective toxicity. Throughout this work I studied two proteins, one that helped to build the cell wall called NagZ and a DNA binding protein called AmpR that regulated the bacterial penicillin resistance gene ampC. Our work used a technique called protein crystallography which is a way to take a snapshot of the three-dimensional position of every atom in a protein so that you can get an accurate picture of it, as you cannot look at them under a microscope since protein are so small (although, this may not be entirely true as much nowadays). We believe that if you can see what a protein looks like, you can better understand what it does (its function), so that you can then design drugs specifically to stop the protein from doing what it is supposed to do (like making the cell wall (NagZ) or turning on antibiotic resistance (AmpR)) and then you will have an easier time killing the infectious bacteria, this is called structure based drug design. Despite my lack of experience going in, I had a successful graduate career, I won 2nd place at my first poster competition at an international conference (ACA 2007, Picture 1D), in my third year submitted a PhD fellowship grant that was rated number 1 in the province and I published 4 papers on my PhD work.

A) Self-portrait B) Participating in the Marbles Museum Family Science Fair outreach day C) Teaching about cloning in the NIEHS-Scholars Connect Program D) Winning 2nd place for my poster at the ACA 2007 D,E) My students (Telah Wingate (D) and Perice Manns (E) at their poster session presenting their work on cloning and expression of the CusS protein variants at the NCAT Undergraduate Research Symposium (Perice, won 3rd place for her poster)

I then moved to Durham NC for my Post-Doc at the National Institute of Environmental Health Sciences (I can talk about this another time), and after 4 years there, found my calling, doing what I wanted to do in the first place…teaching. I was lucky to have a mentor that let me explore teaching opportunities while a Post-doc (Picture B and C). These experiences then led me to taking a position at NCA&T as a lecturer in the department of Biology, where I have been for the last 3 years. During my time at A&T I have been able to thoroughly develop my skills as an instructor teaching General Microbiology (I don’t get to let them feed amoebas but I at least show them the video) and Molecular Biology. Now, what I have been really passionate about, is the work I have done over the last 2 years incorporating my research interests into the courses that I teach. As a lecturer, I have had to adapt the types of projects that I can take on, in addition to becoming creative in searching for research funding, which is why course teaching supplies has been a great asset to me in progressing my work forward. In addition, when students like your classes you can attract high caliber students that belong to programs that come along with research supply money as well. More recently, my research endeavors have been accelerated this past year all thanks to a collaboration that I have been able to develop with Dr. Joseph Graves at the Joint School of Nanoscience and Nanoengineering here at NCAT. Dr. Graves uses experimental evolution and whole-genome sequencing to understand how different bacteria become resistant to heavy metals which normally kill them. Dr. Graves has been studying silver resistance in E. coli, as it was thought that silver is too potent of an antibacterial agent for them to develop resistance to. They then found that they could evolve bacteria to become resistant to 10x the normal toxic levels of silver in only a matter of 9 days! Now in order for bacteria to change what they can do (be resistant) they have to in some way change their DNA, so he sequenced the entire genome (DNA) of his newly resistant E. coli and found changes in three main genes, rpoB which is the RNA polymerase B subunit, involved in transcription (conversion of DNA into RNA), ompR, which helps make protein pumps that let things into the cell and CusS, a protein that senses silver and helps make other proteins that can remove silver from the cell. As a microbiologist/protein biochemist (thanks undergrad!) I was very interested in this project, specifically looking at the CusS protein. I wanted to understand how a single change in this protein could result in a bacterium that was resistant to silver. Therefore, I took this problem into my Molecular Biology class at NCAT where 12 groups designed different version of the protein to be used for protein crystallography and for biochemical analysis to see how the function of this protein changes between the normal one and the resistant one. Incorporation of authentic research experiences into the undergraduate classroom has been one of my major goals as an instructor so that all of my students will have the opportunity to work on a real research project before graduation (unlike me). During the class I had 8 groups successfully clone proteins and 2 groups express soluble protein. After the semester was over 4 students joined my lab to continue their class projects working on CusS (Picture 1E and F). This system of training my students in the classroom has enabled me to start up a small undergraduate run research program in the Department of Biology, that focuses on mechanisms of antimicrobial resistance and right now we are working hard to continue to get protein suitable for protein crystallography and we hope that this information will provide some insight into the actual mechanism of silver resistance in E. coli and to help us understand the ways in which we can potentially counteract this in the future.

When I look back on things now, I am excited about the direction that my career has taken me, and believe that every bump in the road has taken me right to where I am supposed to be. I started out wanting to be a teacher and my education has added a passion for research and now my current career allows me the freedom to take my love for education and my love for research and put them together in a way to excite me and all of my students that I teach every day.

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