Major changes in the Ni-Sp185/333 protein repertoire may not occur until after the second challenge with <i>V</i>. <i>diazotrophicus</i>.

<p>(A) Sea urchin 106 has a limited array of Ni-Sp185/333 proteins prior to immune challenge, with a few high MW proteins of basic pI (arrow). (B) After the first challenge with <i>V</i>. <i>diazotrophicus</i>, the Ni-Sp185/333 proteins appear as more acidic (arrows) plus proteins of ~60 kDa appear (arrow head). (C) After the second challenge with <i>V</i>. <i>diazotrophicus</i>, a significant change in the repertoire of Ni-Sp185/333 proteins shows a shift to more basic pI for both the large MW proteins (arrows), and the ~60 kDa proteins (arrowhead). These images were cropped on the bottom because they do not show spots of less than 50 kDa.