ZEMKE, A.C.; PETER, L.; RIDGWAY, R.L.*: Evidence for a hemoprotein in glial cells of the pond snail, Lymnaea stagnalis

The central nervous systems of many gastropods are distinctly pigmented. This pigmentation ranges from yellow-orange to bright red and has been attributed to the presence of carotenoproteins and/or hemoproteins. L. stagnalis is interesting in that its central ganglia are red-pigmented (suggestive of a hemoglobin) yet it uses hemocyanin as its main respiratory pigment. We used pseudoperoxidase histochemical staining to confirm localization of heme-containing pigments within glial cells of whole-mounted central ganglia. We then used low pressure size exclusion chromatography followed by HPLC to isolate hemoglobin-like molecules from central ganglia homogenates. In the presence of acetonitrile (C-18 column; RP-HPLC), the purified protein exhibited a prominent absorption peak at 395 nm and a much weaker peak at 500 nm. In an aqueous HPLC environment (anion exchange column), however, the purified protein exhibited a dominant peak at 415 nm and two smaller maxima near 540 nm and 575 nm, respectively. These spectra were nearly identical to purified sheep hemoglobin run under the same conditions as a control. These results strongly suggest the presence of a hemoglobin-like protein residing in glial cells of this snail that may serve to protect adjacent neurons during periods of environmental hypoxia. Supported by a SPU Faculty Research Grant to RLR.