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Titolo:
STIMULATION OF REPETITIVE CALCIUM TRANSIENTS IN MOUSE EGGS
Autore:
OZIL JP; SWANN K;
Indirizzi:
INRA,UNITE BIOL FECONDAT F-78352 JOUY EN JOSAS FRANCE ST GEORGE HOSP,SCH MED,MRC,EXPTL EMBRYOL & TERATOL UNIT LONDON SW17 0RE ENGLAND
Titolo Testata:
Journal of physiology
fascicolo: 2, volume: 483, anno: 1995,
pagine: 331 - 346
SICI:
0022-3751(1995)483:2<331:SORCTI>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
SEA-URCHIN EGGS; PARTHENOGENETIC DEVELOPMENT; OOCYTE ACTIVATION; HAMSTER OOCYTES; BOVINE OOCYTES; OSCILLATIONS; ELECTROPORATION; FERTILIZATION; SPIKING; CA-2+;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
39
Recensione:
Indirizzi per estratti:
Citazione:
J.P. Ozil e K. Swann, "STIMULATION OF REPETITIVE CALCIUM TRANSIENTS IN MOUSE EGGS", Journal of physiology, 483(2), 1995, pp. 331-346

Abstract

1. We have combined cell membrane electroporation by electrical field(EF) stimulation with a rapid perfusion system in order to stimulate repetitive increases in cytoplasmic free [Ca2+] ([Ca2+](i)) in mouse eggs. [Ca2+](i) was monitored by ratio fluorescent measurements of intracellular indo-1 on individual eggs. The conditions required to cause different types of [Ca2+](i) increases were established and the effects of these [Ca2+](i) changes upon egg activation examined. 2. The rapid perfusion of non-ionic medium caused a single [Ca2+](i) increase. However, to generate repetitive [Ca2+](i) increases, eggs were exposed to EF pulses in the presence of Ca2+ and then washed rapidly with culture medium. Sequential EF pulse application led to prolonged elevation of [Ca2+](i) levels and eventual cell lysis unless rapid reperfusion with culture medium was achieved. Transient increases in [Ca2+](i) in eggs could also be generated by EP pulses in the presence of inositol 1,4,5-trisphosphate (InsP(3)). 3. In response to EF stimulation fertilized eggs showed [Ca2+](i) increases that were enhanced relative to unfertilized eggs. The responses in these fertilized eggs were often followed by repetitive [Ca2+](i) oscillations, despite the fact that the [Ca2+](i) oscillations associated with sperm penetration had ceased by this stage. 4. In unfertilized mouse eggs the [Ca2+](i) increases appeared to be due to direct cation influx since repeated EF pulses causedrepeated influx of Mn2+ as monitored by quenching of fluorescence of fura-2 loaded eggs. 5. Under conditions that stimulated reproducible patterns of [Ca2+](i) transients we found that a single large [Ca2+](i)transient did not cause significant egg activation, but that inducingrepetitive [Ca2+](i) transients was effective in activating eggs. Thespeed of activation as judged by the rate of pronuclear formation wasalso dependent upon the frequency of pulse application. 6. These datashow that combining EP pulses with a rapid and precise sequential perfusion system can be used to manipulate [Ca2+](i) levels in mammalian eggs. This provides a means of artificial mimicry of the [Ca2+](i) transients seen after fertilization. It appears that Ca2+ influx during EP pulses does not cause significant Ca2+ release from internal stores in unfertilized eggs, but after fertilization Ca2+ influx does induce Ca2+ release. It is also apparent that mouse eggs are more successfully activated by repetitive [Ca2+](i) increases than by single large [Ca2+](i) rises. We suggest that our data provide direct evidence for thehypothesis that a cellular response to oscillations of intracellular [Ca2+](i) can be distinct from that to monotonic rises in [Ca2+](i).

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Documento generato il 26/09/20 alle ore 05:18:28