Phospholipase C zeta, the trigger of egg activation in mammals, is present in a non-mammalian species

• The activation of the egg to begin development into an embryo is triggered by a sperm-induced increase in intracellular egg Ca2+. There has been much controversy about how the sperm induces this fundamental developmental event, but recent studies suggest that, in mammals, egg activation is triggered by a testis-specific phospholipase C: PLC zeta. Since the discovery of PLC zeta, it has been unclear whether its role in triggering egg activation is common to all vertebrates, or is confined to mammals. Here, we demonstrate for the first time that PLC zeta is present in a non-mammalian vertebrate. Using genomic and cDNA databases, we have identified the cDNA encoding a PLC zeta orthologue in the domestic chicken that, like the mammalian isoforms, is a testis-specific gene. The chicken PLC zeta cDNA is 2152 bp in size and encodes an open reading frame of 639 amino acids. When injected into mouse oocytes, chicken PLC zeta cRNA triggers Ca2+ oscillations, indicating that it has functional properties similar to those of mammalian PLC zeta. Our findings suggest that PLC zeta may have a universal role in triggering egg activation in vertebrates.

Nyckelord

ca2+ oscillations

mouse oocytes

calcium oscillations

protein factor

plc-zeta

fertilization

sequence

sensitivity

maturation

contain

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