Most of the researchers in my lab conduct studies using E. coli or other bacterial model systems. Themes in lab include the study of gene circuits, growth patterns, and bacterial tolerance to antibiotics. My project this summer involves the study of bacterial conjugation, or the inter-cellular transfer of genetic material, and how the rate of conjugation can be modulated by such factors as antibiotic concentration in the media as well as the presence of “bystander” bacterial populations (also capable of conjugating). I am working with Ph. D student Allison Lopatkin, who has studied this concept extensively over the past several years. Her research suggests that conjugation between bacteria is highly relevant in the spread of antibiotic resistance-associated genes within bacterial populations!
Though Allison has studied conjugation dynamics in great detail in vitro (i.e. in the petri dish), we wonder whether these same results hold true when the bacteria are conjugating while living in a living organism. This would obviously be very important if the work is to have implications for people—it is not enough to simply prove that these trends exist in the petri dish, a simulated environment for the bacteria. To address this, we mean to utilize the bacteria-consuming nematode C. elegans to measure the rate of conjugation of the bacteria in vivo (while living in the gut of the worms). To quantify the conjugants in the gut of the worm, we intend to use flow cytometry to detect certain fluorescence signatures that we’ve designed to only be present in recipients of conjugated DNA. Before running the bacteria through flow however, we must first remove them from the guts of the worms; to do this, we are using a mechanical grinder capable of homogenizing the worms despite their microscopic sizes!
We received the worms last Tuesday, and after several days of getting used to cultivating the worms as well as conducting test-runs on some of our preliminary control experiments, I believe we are making really good progress so far!
Source: Judith Kimble, University of Wisconsin Madison
