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Activation currents, sperm entry and surface contractions in ascidian eggs

Published online by Cambridge University Press:  26 September 2008

C. Pecorella ,
E. Tosti ,
K. Kyozuka  and
B. Dale
C. Pecorella
Affiliation:
Stazione Zoologica, Naples, Italy.
E. Tosti
Affiliation:
Stazione Zoologica, Naples, Italy.
K. Kyozuka
Affiliation:
Stazione Zoologica, Naples, Italy.
B. Dale*
Affiliation:
Stazione Zoologica, Naples, Italy.
*
B. Dale, Stazione Zoologica, Villa Comunale, 80121 Naples, Italy. Telephone: 39 81 5833233; Fax: 9 81 7641355.
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Summary

Spermatozoa from the mollusc Ostrea edulis are capable of fusing to and entering de-chorionated ascidian eggs. During interaction they generate activation currents, comparable to the fertilisation currents induced by homologous spermatozoa. Activation currents are inward at − 80 mV, with a mean initial slope of 111 ± 124 pA/s for Ciona intestinalis eggs and 47 ± 25 pA/s for Phallusia mammillata eggs, while the mean peak currents are 2782 ± 1132 pA and 1523 ± 1668 pA, respectively. The fertilisation and activation currents reverse at a holding potential of 0 mV to + 20 mV, suggesting that oyster sperm and ascidian sperm gate the same channel precursor, a non-specific, large conductance channel described previously (Dale & DeFelice, 1984). In contrast to homologous fertilisation, the activation current is not followed by a polarised contraction of the egg surface, nor other signs of egg activation. Staining eggs with Hoechst 33342 after insemination shows the female nucleus and a single oyster sperm nucleus at the antipode. This suggests a specialised predetermined site at the vegetal pole for sperm entry. Homologous and heterologous spermatozoa delivered, in a large pipette, to localised areas of the egg surface generate fast inward currents of 200–2000 pA, but do not induce contraction of the egg surface. This shows that although channel precursors are located globally over the egg surface, channel activation does not necessarily trigger the contraction wave. Subsequent induction of both a fertilisation current and a contraction by homologous sperm added to the bath, implies a regionalised activation site with an accumulation of channel precursors and a ‘pacemaker’ for the initiation of the contraction wave.

Keywords

Ascidian eggsActivation currentsEntry sites
Type
Article
Information
Zygote , Volume 1 , Issue 2 , May 1993 , pp. 113 - 119
Copyright
Copyright © Cambridge University Press 1993

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References

Brownlee, C. & Dale, B. (1990). Temporal and spatial correlation of fertilization current, calcium waves and cytoplasmic contraction in eggs of Ciona intestinalis. Proc. R. Soc. Lond. B 239, 321–8.Google ScholarPubMed
Conklin, E. (1905). The organization and cell lineage of the ascidian egg. J. Acad. Nat. Sci. Philad. 13, 1–119.Google Scholar
Dale, B. (1990). Mechanism of Fertilization: Plants to Humans. NATO ASI Cell Biology Series H45. Springer-Verlag, Heidelberg.CrossRefGoogle Scholar
Dale, B. & DeFelice, L.J. (1984). Sperm activated channels in ascidian oocytes. Dev. Biol. 121, 235–9.CrossRefGoogle Scholar
Dale, B. & Talevi, R. (1989). Distribution of ion channels in ascidian eggs and zygotes. Exp. Cell. Res. 177, 205–11.CrossRefGoogle Scholar
Dale, B., DeFelice, L. & Taglietti, V. (1978). Membrane noise and conductance increase during single spermatozoon-egg interactions. Nature 275, 217–19.CrossRefGoogle ScholarPubMed
Dale, B.,Desantis, A. & Ortolani, G. (1983). Electrical response to fertilization in ascidian oocytes. Dev. Biol. 99, 188–93.CrossRefGoogle ScholarPubMed
DeFelice, L. & Dale, B. (1979). Voltage response to fertilization and polyspermy in sea urchin eggs and oocytes. Dev. Biol. 72, 327–41.CrossRefGoogle ScholarPubMed
DeFelice, L.J. & Kell, M.J. (1986). Sperm-activated currents in ascidian oocytes. Dev. Biol. 119, 123–8.CrossRefGoogle Scholar
DeFelice, L.J., Dale, B. & Talevi, R. (1986). Distribution of fertilization channels in ascidian oocyte membranes. Proc. R. Soc. Lond. B 229, 209–14.Google ScholarPubMed
Iwao, Y. (1985). The membrane potential changes of amphibian eggs during species and cross-fertilization. Dev. Biol. 111, 26–34.CrossRefGoogle Scholar
Jaffe, L.A., Gould, Somero M. & Holland, L.Z. (1982). Studies of the mechanisms of the electrical polyspermy block using voltage clamp during cross-species fertilization. J. Cell Biol. 92, 616–21.CrossRefGoogle ScholarPubMed
Jaffe, L.A., Cross, N.L. & Picheral, B. (1983). Studies of the voltage-dependent polyspermy block using cross-species fertilization of amphibians. Dev. Biol. 98, 319–29.CrossRefGoogle ScholarPubMed
Lynn, J. & Chambers, E. (1984). Voltage clamp studies of fertilization in sea urchin eggs. I. Effect of clamped membrane potential on sperm entry, activation and development. Dev. Biol. 102, 98–109.CrossRefGoogle ScholarPubMed
Nuccitelli, R., Cherr, G. & Clark, W. (1989). Mechanisms of Egg Activation. Bodega Marine Laboratory Marine Science Series. New York: Plenum Press.Google Scholar
Ortolani, G. (1957). Azione della tripsina sul cortex dell'uovo di Phallusia mamillata, Ric. Sci., 27, 1175.Google Scholar
Osanai, K. & Kyozuka, K. (1982). Cross fertilization between sea urchin eggs and oyster spermatozoa. Gamete Res. 5, 49–60.CrossRefGoogle Scholar
Osanai, K., Kyozuka, K., Sato, H., Hirai, S., Igusa, Y. & Miyazaki, S. (1987). Bioelectric responses of sea urchin eggs inseminated with oyster spermatozoa: a sperm evoked potential without egg activation. Dev. Biol. 124, 309–15.CrossRefGoogle ScholarPubMed
Sawada, T. & Osanai, K. (1981). The cortical contraction related to the ooplasmic segregation in Ciona intestinalis eggs. Wilhelm Roux's Arch. Dev. Biol. 190, 208–14.Google Scholar
Sawada, T. and Schatten, G. (1989). Effects of cytoskeletal inhibitors on the ooplasmic segregation and microtubule organization during fertilization and early development in the ascidian Molgula occidentalis, Dev. Biol., 132: 331–342.CrossRefGoogle ScholarPubMed
Speksnijder, J., Corson, W., Sardet, C. & Jaffe, L. (1989a). Free calcium pulses following fertilization in the ascidian egg. Dev. Biol. 135,182–90.CrossRefGoogle ScholarPubMed
Speksnijder, J., Jaffe, L. & Sardet, C. (1989b). Polarity of sperm entry in the ascidian egg. Dev. Biol. 133, 180–4.CrossRefGoogle ScholarPubMed
Speksnijder, J., Sardet, C. & Jaffe, L. (1990). The activation wave of calcium in the ascidian egg and its role in ooplasmic segregation. J. Cell Biol. 110, 1589–98.CrossRefGoogle ScholarPubMed
Talevi, R., Campanella, C. & Dale, B. (1985). Fertilization and activation potentials in Discoglossus pictus (Anura): a delayed response to activation by pricking. Dev. Biol. 111, 316–23.CrossRefGoogle Scholar
Tosti, E. & Dale, B. (1991). Lithium and phorbol ester modify the activating capacity of ascidian spermatozoa. Experientia 48, 57–60.CrossRefGoogle Scholar