Spring 2013 Classes
A. Tight Junction Phylogeny
With the DNA samples, researchers are able to amplify and analyze specific genes (tight junction molecules, for example). The nucleotide sequences of these genes can be compared to sequences of other organisms in the National Center for Biotechnology Information (NCBI) and other databases. The similarities (and differences) observed between organisms can be used to infer evolutionary relatedness. When these comparisons are performed between numerous organisms simultaneously, researchers can construct phylogenetic or evolutionary trees with respect to molecular sequences. These evolutionary trees not only indicate evolution of entire species, but can help us to better understand how specific gene sequences have changed over time, and how those structural changes relate to functional changes. Samples collected from the Ambergris Caye reef area (in Belize C.A.) can help with this collective and ever-growing body of knowledge.
Specifically, my interests focus on genes involved in the establishment of tight junctions. Epithelial and endothelial cells establish barriers between compartments of tissue and organ systems. This barrier is established by a complex of tight junction proteins between neighboring cells. Tight junctions cause cells to come into intimate contact with each other to the point that the intercellular space is almost non-existent. Tight junctions are used to prevent the lateral movement of membrane associated proteins and to regulate the transport of essential ions like sodium, chloride, calcium, and magnesium. Tight junctions establish a semipermeable barrier that regulates paracellular transport of solutes with charge and size selectivity through the intercellular space.
To perform this work, I will collect tissue samples of invertebrate and fish species from the patch reefs and back reef areas off Ambergris Caye, Belize between February and April 2013. These samples will be transported to the US where genomic DNA isolation techniques will be performed to create a “catalog” of tissue samples from Belizean corals, sponges and other species for phylogenetic analysis.
B. Molecular and Cell Biology of Proliferative Vitreoretinopathy
Proliferative vitreoretinopathy (PVR) is an ophthalmological condition in which the retinal pigment epithelium (RPE) cells break free from their monolayer in the posterior retina and migrate into the vitreous chamber. This results in an estimated 10% of patients who suffer from retinal detachments with retinal tears. During PVR, the RPE undergoes an epithelial mesenchymal transformation (EMT) as the intercellular adherens and tight junctions break down between cells. Epithelial and endothelial cells are joined to one another through a junctional complex that includes an adherens junction and an occludens or tight junction. Recent studies from other labs has shown that the loss of cell adhesion during EMT is, in part, under the control of the Notch pathway and that loss of tight junction expression is regulated by the zinc finger repressor Snail, which downregulates the expression of the tight junction molecules occludin and claudin as well as the adhesion molecule E-cadherin.
My lab examines the possible role of the Snail family of transcription factors (Snail and Slug) in the EMT associated with PVR using a pig RPE cell model. Using a combination of molecular and cell biological techniques, we are examining the expression levels of adherens and tight junction molecules following exposure of RPE to freshly isolated vitreous. Specifically, the roles of the Snail family of transcription repressors will be studied.
A number of undergraduate research assistants will work on different aspects of this project which will serve as a learning and research training experience for them. Data gathered during the scope of this work will help to broaden the ophthalmological community's understanding of the molecular triggers that bring about the phenotypic changes observed during PVR.
If you have questions or comments, email me at: firstname.lastname@example.org.
Department of Biology
2001 Newburg Road
Louisville, KY 40205