Meeting Abstract
P1.117 Thursday, Jan. 3 Live-Cell Imaging of Zinc Sequestering by Hemocytes of the Pond Snail, Lymnaea stagnalis RIDGWAY, R.L.*; MANN, P.R.; BRISBANE, W.; Seattle Pacific University; Seattle Pacific University; Seattle Pacific University rridgway@spu.edu
Certain molluscs, such as the Eastern oyster Crassostrea virginica, can withstand exposure to potentially toxic levels of copper and zinc. Moreover, they can accumulate these metals from low ambient concentrations by sequestering the ions within immune system cells variously known as amebocytes or hemocytes. We examined whether a similar sequestering of zinc might occur within hemocytes of the freshwater snail Lymnaea stagnalis. To trace labile zinc we loaded isolated hemocytes with the zinc-specific probe FluoZin-3 before exposing the cells to ZnCl2 (range: 10-3 to 10-9 M) for 15 to 120 min. FluoZin-3 fluorescence was localized to membrane-bound vesicles within the cytosol of the hemocytes, especially in cells exposed to higher concentrations of ZnCl2 (10-3 to 10-5 M). Further experiments, using 10-5 M ZnCl2, revealed that initial sequestering occurs within smaller (approx. 50 nm diam.) vesicles of the peripheral cytosol. These vesicles appear to enlarge, perhaps via fusion events, and move more centrally in the cytosol over time. Experiments combining FluoZin-3 with the pH-sensitive (acidic) probe LysoTracker Red suggest that some of the zinc-containing vesicles enter the endosomal-lysosomal pathway. Thus, zinc sequestering occurs in L. stagnalis hemocytes, but it remains to be determined which specific uptake method is used by the cells during the process. (Supported by an SPU Senior Faculty Research Grant to RLR.)
