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Fig. 4. (A) and (B) A typical increase in [Ca2+]i induced by the fertilizing sperm in a dejellied egg, showing the propagation of a Ca2+ wave from the sperm entrance site toward the opposite site. The increase in [Ca2+]i was initiated 5 min after insemination and continued about 5 min. The second increase in fluorescence intensity (*) is an artifact by the appearance of white surface of vegetal hemisphere during cortical contraction after passing the Ca2+ wave. Numbers on the top right of figures (C and D) show time (min) after insemination. Bar, 0.5 mm. (C) and (D) A typical increase in [Ca2+]i induced by the treatment of the HPX peptide (473–485; GMSQIRGETFFFK, 2 mM, 20 µL) in a dejellied egg, showing the increase in [Ca2+]i which was initiated 4 min after treatment and spread over the egg surface for 3 min. The resumption meiosis in metaphase II-arrested unfertilized eggs (D-a) was confirmed by the formation of an egg pronucleus (D-b). The second peak in fluorescence intensity (*) is an artifact by the appearance of white surface of vegetal hemisphere during cortical contraction after passing the Ca2+ wave. Numbers on the top right show time (min) after treatment. Bar, 0.5 mm (A) and 10 µm (D). (E) The activation of dejellied eggs by the treatment with the HPX peptides, showing higher activities by GMSQIRGETFFFK (473–485) (a) and by RGETFFK (478–485) (c), but lower activity by GMSQIAGETFFFK (R475A) (b). In each column, 40–50 eggs were examined (mean ± SEM, n = 4). (F) The activation of denuded eggs by the treatment with agarose-beads conjugated by GMSQIRGETFFFK (473–485), indicating signal transduction for egg activation on the egg plasma membrane. In each column, 37–45 eggs were examined (mean ± SEM, n = 3). Image published in: Iwao Y et al. (2014) Copyright © 2014. Image reproduced with permission of the Publisher, Elsevier B. V. Larger Image Printer Friendly View

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