TY - JOUR

T1 - Calcium influx, fertilisation potential and egg activation in fucus serratus

AU - Roberts, Stephen

AU - Brownlee, Colin

PY - 1995/8/31

Y1 - 1995/8/31

N2 - Fertilisation in the marine alga Fucus serratus is accompanied by increased influx of Ca2+ from the external medium. The onset of this increase, monitored with the Mn2+ fluorescence quench technique, corresponded with the depolarisation phase of the fertilisation potential. External Ca2+ was necessary for the onset of the fertilisation potential and the early activation events, including cell wall exocytosis. Removal of Ca2+ from, or addition of Sr2+ to, the external medium during the fertilisation potential reduced the magnitude of the depolarisation and prolonged its duration. While fertilisation potentials could not be elicited in the presence of 0.1 mM Ca2+, addition of Ba2+ in the presence of 0.1 mM Ca2+allowed normal fertilisation potential and egg activation. Ivlicroinjection of ryanodine or cyclic guanosine 5’-monophosphate (cGMP) did not induce cytoplasmic Ca2+ elevation or egg activation. Inositol 1,4,5-triphosphate [Ins(l,4,5)P3] produced a transient elevation of cytoplasmic Ca2+, monitored using ratio photometry, but did not cause cell wall exocytosis except at the site of microinjection. The results demonstrate an essential role for Ca2+ influx during Fucus egg activation. The relative importance of influx and intracellular Ca2+ release in Fucus egg activation is discussed.

AB - Fertilisation in the marine alga Fucus serratus is accompanied by increased influx of Ca2+ from the external medium. The onset of this increase, monitored with the Mn2+ fluorescence quench technique, corresponded with the depolarisation phase of the fertilisation potential. External Ca2+ was necessary for the onset of the fertilisation potential and the early activation events, including cell wall exocytosis. Removal of Ca2+ from, or addition of Sr2+ to, the external medium during the fertilisation potential reduced the magnitude of the depolarisation and prolonged its duration. While fertilisation potentials could not be elicited in the presence of 0.1 mM Ca2+, addition of Ba2+ in the presence of 0.1 mM Ca2+allowed normal fertilisation potential and egg activation. Ivlicroinjection of ryanodine or cyclic guanosine 5’-monophosphate (cGMP) did not induce cytoplasmic Ca2+ elevation or egg activation. Inositol 1,4,5-triphosphate [Ins(l,4,5)P3] produced a transient elevation of cytoplasmic Ca2+, monitored using ratio photometry, but did not cause cell wall exocytosis except at the site of microinjection. The results demonstrate an essential role for Ca2+ influx during Fucus egg activation. The relative importance of influx and intracellular Ca2+ release in Fucus egg activation is discussed.

KW - Calcium

KW - Egg activation

KW - Fertilisation potential

KW - Fucus serratus

U2 - 10.1017/S0967199400002586

DO - 10.1017/S0967199400002586

M3 - Journal article

C2 - 8903788

AN - SCOPUS:0029347815

VL - 3

SP - 191

EP - 197

JO - Zygote

JF - Zygote

SN - 0967-1994

IS - 3

ER -