A nucleic acid sequence, including an isolated, purified or recombinant nucleic acid sequence, includes: (a) a nucleic acid sequence encoding a polypeptide encompassed by the present invention, namely, a PLC-zeta; PLC.zeta. amino acid sequence, capable of triggering calcium oscillations in oocytes; (b) a sequence substantially homologous to or that hybridizes to sequence (a) under stringent conditions; (c) a sequence substantially homologous to or that hybridizes to the sequences (a) or (b) but for degeneracy of the genetic code; and (d) an oligonucleotide specific for any of the sequences (a), (b) or (c) above.