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Asymmetric Cell Division in the Model Organism C. elegans (Bob Goldstein Lab)

Mara Duncan

A living cell is an astounding feat of organization and is often compared to a metropolitan center.  In a city, people, products, etc. move between offices, factories,  and other buildings using various means of transportation—the eukaryotic cell’s “buildings” (the organelles) are likewise linked by different traffic routes, which transport molecules between a cell’s many compartments, the cytosol, and the extracellular space.  The coordination of these cellular transport systems is crucial to the function of the cell, and if it is lost the harmony of the cells actions can also be lost. This may lead to abnormalities in cell growth, proliferation, and differentiation, and the disease states caused by such irregular patterns of cell behavior.

One method of cellular transport is vesicular transport, where small “bags” of membrane bud from a donor compartment in a way that can be crudely compared to soap bubbles budding from a thin, soapy film (see the figure below).  The transport vesicles travel through the cytosol and fuse with the membrane of their particular target (picture the reverse of soap bubble formation), and through this fusion they both empty their contents into the target’s interior and contribute to its membrane.  Transport vesicle formation, fusion with the target membrane, and often the movement from origin to destination, are functions performed by assemblies of proteins, acting sequentially or together as tiny machines.

Mara Duncan, PhD., is a molecular cell biologist who’s recently joined the Biology Department here at UNC.  Dr. Duncan and her lab study vesicular transport, and the molecular interactions responsible for it, using a variety of genetic and biochemical methods.  The lab is currently seeking post-doctoral fellows, graduate students, and undergraduate students.  When mentioning undergraduate research, Dr. Duncan states “I think my lab is ideal for undergrads.  We have projects where somebody can come in with very little prior training and start making contributions right away.”

One of Dr. Duncan’s projects is a 2-hybrid screen, a technique often used to determine whether or not two proteins interact.  One of the proteins (call it “P1”) may be known to have a role in a particular cellular process; vesicular transport, for example.  The other protein (“P2”) may potentially play a role in that same process.  If an interaction between the known protein P1 and the unknown protein P2 is found using a 2-hybrid screen, the next task is to find out whether or not P2 is involved in this process and, if so, what might it be doing?  

To this end, the student can search through protein databases to obtain information about the P2 protein, and develop a hypothesis about how it might work.  The student can either produce or purchase a “knockout” (an organism lacking a functional P2 protein) and look for disruptions in the cellular process being studied.  The student could also generate a GFP fusion protein, P2-GFP (which involves the protein P2 being joined, or fused, to “green fluorescent protein” via genetic recombination techniques), allowing the cellular location of the P2 protein to be determined using fluorescent microscopy (the figure to the right* shows yeast cells expressing GFP).   After collecting information in these ways, the student could gain evidence for a conclusion that the protein P2, which previously may have been of unknown function, has a role in a specific cellular process.  With hard work and a little luck, Dr. Duncan explains, “An undergrad could really come in with a project that was initially designed to go for just a semester (to do a 2-hybrid screen), and it could lead into a very high-impact project that the student could be involved in every aspect of.”

In closing, it’s important for any fledgling researcher to understand that research generally isn’t what it’s depicted to be in popular culture.  Speaking of the day-to-day work done in a lab in general, Dr. Duncan says “…some of it’s a little bit mindless, [e.g. sometimes you’re] transferring one clear liquid to another clear liquid and now you have to wait for 15 minutes, and so, it’s an environment where you really get to know your colleagues and develop very strong friendships, and you learn from one another.”  Dr. Duncan believes that research is a social and collaborative effort as well as an academic effort.  “That’s really the advantage of being in a laboratory setting.  It’s not just you, there’s a whole group of people, and it’s not just the mentor and the student, or the researcher, but it’s all the researchers who contribute to the research environment, the quality of research that’s done in the lab.”