Visualization of the molecular dynamics of lipopolysaccharide on the plasma membrane of murine macrophages by total internal reflection fluorescence microscopy.

The molecular action of Alexa 594-labeled lipopolysaccharide (LPS) from Escherichia coli was examined on living peritoneal macrophages of C57BL/6 mice by total internal reflection fluorescence microscope (TIRFM), and the molecular kinetics of LPS was analyzed. TIRFM visualization of the action of fluorescence-labeled LPS revealed an increase in the mean fluorescence intensity of LPS on the plasma membrane of wild type macrophages at 60 min after administration, indicating the oligomerization of LPS after binding to the macrophages. Additionally, a time-dependent sharp decrease in the mean diffusion coefficient of LPS was observed.

Fertilization envelope formation induced by melittin in sea urchin eggs does not depend on Ca signalling.

In sea urchin eggs, 10 μg/mL melittin was found to induce fertilization envelope formation without any increase in [Ca ] (the intracellular free Ca level). On the other hand, 10 μmol/L Br-A23187 and 100 μg/mL SDS induced fertilization envelope formation associated with [Ca ] increase. If EGTA was injected into eggs to make an intracellular concentration of 2 mmol/L, [Ca ] became quite low and was not altered by melittin, or by Br-A23187 and SDS.