Bioassays of the calcium-depleted or -supplemented Osmerus eperlanus parvalbumins.

The chemoattractivity of the purified parvalbumins was assessed according to a standard “all-or-none” snake bioassay based on a non-biological lure coated with the tested sample as in [9]. The test was considered positive if the snake attacked the lure within 20 sec after the first lure-directed tongue flick. The test was considered negative in any other circumstances. A/B corresponds to the number of positive tests/total tests. The purified form of Osmerus eperlanus α and β parvalbumins were obtained following the procedure described in [33]. The apo-parvalbumin was prepared by incubating the purified parvalbumin with a calcium-chelating agent (2 mM EDTA) and was then dialysed to remove the EDTA. ND = not determined.