The Squirmiest Worms

Elizabeth Ejzak is a senior majoring in Chemistry. She was awarded a Summer 2018 Independent Grant which he used to conduct research on the effects of plant extracts on health span under Dr. Daniel Kalman and Dr. Cassandra Quave. 

Have you ever wondered why we cannot remain springy, spry, and free of illness forever?  If so, you are in luck.  In recent years, there has been a huge increase in the number of studies into aging mechanisms, and delaying their onsets.  While there are theoretically infinitely many approaches, we fortunately have some insight on the keys to longevity.   Cultures in regions such as the Mediterranean who consume higher quantities of plant-based foods, healthy fats and whole grains and lower quantities of animal-based foods tend to live the longest, while also delaying the onset of senescence, or age-related deterioration.  

Part of how I started into this line of work was total luck.  At the beginning of my freshman year, I was in need of a work-study job, and I knew I wanted to do some sort of research.  Within the first week of school, I was hired by the Kalman lab, in Emory's department of experimental pathology.  I began work as a dishwasher, cleaning glassware, sterilizing bench tops and taking out the trash.  After about a year and a half of building up a repertoire of laboratory techniques and learning about the lab’s research through weekly lab meetings, Dr. Kalman and I agreed that it was time I start doing my own research.  Even luckier, at the same time, Dr. Cassandra Quave had just returned from harvesting plant extracts from all over the world and was in need of someone to run biological assays on them to see which were biologically active and conducive to an extended healthspan. The concept of healthspan is the period of time an organism is still motile, resistant to stressors and free of illness.  The task fell to me to determine how to screen hundreds of extracts for their biological activity.  Once I identified an extract that seemed to have an effect, that extract would be separated via fractioning into its constituent components, and I would screen it again to see which components caused the activity.  The aim is to identify a single molecule, or several molecules working in tandem, to cause the effect, so that a mechanism can be determined.  Subsequently, this molecule or group of molecules can be implemented in dietary recommendations and supplements, as well as therapeutics, to treat aging-related conditions.   

Needless to say, I was a bit overwhelmed.  People frequently talk about doing “research”, just throwing the word around casually.  The truth is, it is really challenging to come up with an idea that no one has done before.  Despite there being an infinite amount of information we do not know, the tough thing is that we do not even know what we do not know.  It is scary for sure, but also humbling and comforting at the same time. The beginning of such a big research project is sort of like a Jackson Pollock painting, you just throw a bunch of ideas out there and hope one sticks.  For a model organism, I decided to use the nematode species C. elegans because worms are cheap and you can run assays on many of them at once, so it is easy to see a statistically significant effect. I began my work using high-throughput stress assays.  C. elegans share many stress-response pathways in humans, so their response to a stressor is typically analogous to ours. An assay that gave interesting results was the oxidative stress assay.  Within our bodies, molecules are constantly, spontaneously cleaving in half, producing a reactive species known as free radicals.  Free radicals are unique because they contain a single unpaired electron in their outer valence shell, and are desperate to pair up with another. 

Thus, free radicals will react with anything and everything in order to claim this electron, including proteins, lipids, and DNA.  Such a reaction damages these molecules and accelerates the aging process.  However, our bodies produce antioxidants, which are sort of like a shield. Antioxidants react with free radicals so that they do not attack our vital bio-molecules.  As we age, our body produces fewer antioxidants, which is why we become more susceptible to the phenotypes associated with aging. Antioxidants can also be consumed from plants, which, in theory, keep us healthier for longer.  Of the 96 extracts I screened in this oxidative stress assay, only one seemed to outperform the control.  It was an extract of the flowers of Robinia pseudoacacia, a tree that grows on essentially every continent, except Antarctica.  The potential of this extract being an antioxidant-containing one was very exciting.  I continued to run oxidative stress assays on this extract alone and worms exposed to the extract versus a DMSO control (all of the extracts were dissolved in DMSO) were motile and living for longer.  

Resuming my research this summer, I decided to try a different type of experiment.  Instead of an acute stress assay, I wanted to try a conditioning assay, in which I would analyze the organisms over the course of their entire lifespan, monitoring their motility at many time points along the way and exposing them to either extract or a control every other day, to see whether consistent exposure augments health span.  Oxidative stress occurs naturally in organisms anyway, so that stressor would still be included.  Once again, after in-depth data analysis, I observed a significant separation in the motility of the worms.  While the control group’s motility began to decline steadily at day 13-15 of experimentation, the group exposed to extract continued to move well even at day 23.  I ran this experiment twice, and got the same result both times, which is super encouraging! Moving forward, I want to expand experimentation to include different types of motility assays, try different model organisms such as fruit flies and tissue culture cells, and use fluorescent staining as an easy but very distinct detection method.  I am excited to see how the molecules in this extract interact with both each other and host organisms, and, hopefully, implement it into some sort of therapeutic.       

            

Visit the Undergraduate Research Programs website to learn more about applying for Independent Research Grants.