Presenter:  Jacqueline W. Nyoro
Faculty Advisor:  Dr. Nadia Marano
Phone# x6763
 jnyoro46@mailbox.stlawu.edu

Poster Presentation

Cell membranes consist of a variety of lipids arranged in a bilayer with embedded proteins. The lateral organization of the lipids is partly as a result of packing of certain specific lipids into moving rafts. These are hypothesized to serve as sites of attachment of some proteins. However, proteins are mostly embedded in the bilayer in the absence of raft association. Jurkat leukemia T cells were used to test whether exogenous lipids known to be found in rafts affect important signaling events.   Previous experiments have shown that a specific raft lipid GM3 affects the T-cell membrane protein CD4.  Antibodies specific to T-Cell Receptors can activate the cell, causing internal signals similar to normal activity.  One such internal signal is to increase Ca2+concentration in the cell.  Half of the cells were GM3-treated, and the other half were the control. The samples were incubated a dye whose fluorescence changes when Ca2+ binds.  Fluorescent spectrometer readings were taken using the FT Winlab program.  After the signal had stabilized, the  anti-TCR antibody was added. The spectrometer calculates the ratio of the Ca2+ bound to the unbound dye, and graphs the results.  Using a ratio of the signal reduces the effects of uneven dye loading, dye leakage and non-uniform cell thickness. The results showed that the treatment of the cells with GM3 did not result in a difference in treated and untreated cells. Both responded with a large increase in intracellular Ca2+ concentration.  Thus this lipid does not affect this aspect of signaling.