Gap junctional units are functionally expressed before 1st cleavage
in the early ascidian embryo.
Tosti, Elisabetta.
Department of Cell and Developmental Biology, Stazione Zoologica,
Villa Comunale, 80121 - Napoli- Italy
APStracts 3:0370C, 1996.
Manually apposed ascidian zygotes established electrical communication
within 50 minutes of fertilization and before cytokinesis. Junctional
conductance between zygotes was 14.5 & 2.9 nS (n=7), similar to
that previously reported for ascidian two cell stage blastomeres
suggesting that zygotes and blastomeres express an equivalent number
of gap junctional half channels. Because puromycin at 400 uM does not
inhibit the functional expression of these half channels, they appear
to be of maternal origin and their activation does not require
protein synthesis. Loading zygotes with 500 mM EGTA or exposing
zygotes to 10 uM of the calcium ionophore A23187, shows that these
half channels are regulated by intracellular calcium consistent with
the behaviour of these channels in adult tissues. The results show
that gap junctions units are expressed in the ascidian at the zygote
stage.
Received 29 July 1996; accepted in final form 18 November 1996.
APS Manuscript Number C419-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996