Figure 2. Fucose-sulphate glycoconjugate (FSG)-induced changes in [Na⁺]_i, [Ca²⁺]_i and pH_i in the absence (A, B, C) and presence of saturating concentrations of speract (D, E, F).

Sperm loaded with SBFI AM, fura-2 AM and BCECF AM, as indicated in Methods, were suspended in artificial sea water (ASW) for 2 min before the recordings were started. At the time indicated by the arrows, saturating levels of FSG (5-20 μl), the acrosome reaction (AR) inducer, were added. In D, E and F, two 100 nm speract (sp) additions were made before exposing the sperm suspension to saturating levels of FSG. The percentage of AR (%) is shown at the end of the traces. The [Na⁺]_i, [Ca²⁺]_i and pH_i records shown are representative of at least nine different batches of sea urchin sperm, with the exception of the [Na⁺]_i increase induced by FSG alone, where n = 3.