Variability of sperm specific histones in sea urchins

The variability of sperm histones was compared in two species of sea urchin . Whole sperm specific histones (SpH), were isolated from Tetrapygus niger (Arbacoida) and Pal echinus angulosus (Echinoida). Individual histones were purified by chromatography on BioGel P-60 followed by reverse high pressur e liquid chromatography (HPLC). The heterogeneity of each major histone typ e from T. niger was established from their HPLC elution patterns and furthe r confirmed by electrophoresis in polyacrylamide gels containing 6 mM Trito n X-100 combined with a transverse urea gradient (0-8 M). In T. niger, as w ell as in P. angulosus, a single form of Spill and SpH2A were found. In con trast, SpH2B was found to be heterogeneous, but represented by one major fo rm in both species. The relatedness between both sets of histones was deter mined by establishing their immunological cross-reactivity. In this context , polyclonal antibodies elicited against T. niger sperm histones were assay ed against individual histones from P. angulosus. From the results obtained , it emerged that histone SpH2A was the more closely related protein betwee n these two species, followed by histone Spill. In contrast, histone SpH2B was found to be only moderately related. These results confirm that SpH2A d id not co-evolve with SpH2B, as was predicted for most species. (C) 2001 El sevier Science Inc. All rights reserved.