Phospholipase C-ζ-induced Ca2+ oscillations cause coincident cytoplasmic movements in human oocytes that failed to fertilize after intracytoplasmic sperm injection

Capsule:
PLCz-induced Ca2+ oscillations in human oocytes that failed to fertilize after intracytoplasmic sperm injection cause small, discrete movements in the cytoplasm that provide a noninvasive measure of the pattern of Ca2+ transients during activation.

Authors:
Karl Swann, Ph.D., Shane Windsor, Ph.D., Karen Campbell, Ph.D., Khalil Elgmati, M.Sc., Michail Nomikos, Ph.D., Magdalena Zernicka-Goetz, Ph.D., Nazar Amso, Ph.D., F. Anthony Lai, Ph.D., Adrian Thomas, Ph.D., Christopher Graham, D.Phil.
Volume 97, Issue 3 , Pages 742-747, March 2012

Objective:
To evaluate the imaging of cytoplasmic movements in human oocytes as a potential method to monitor the pattern of Ca2+ oscillations during activation.

Design:
Test of a laboratory technique.

Setting:
University medical school research laboratory.

Patient(s):
Donated unfertilized human oocytes from intracytoplasmic sperm injection (ICSI) cycles.

Intervention(s):
Microinjection of oocytes with phospholipase C (PLC) zeta (ζ) cRNA and a Ca2+-sensitive fluorescent dye.

Main Outcome Measure(s):
Simultaneous detection of oocyte cytoplasmic movements using particle image velocimetry (PIV) and of Ca2+ oscillations using a Ca2+-sensitive fluorescent dye.

Result(s):
Microinjection of PLCζ cRNA into human oocytes that had failed to fertilize after ICSI resulted in the appearance of prolonged Ca2+ oscillations. Each transient Ca2+ concentration change was accompanied by a small coordinated movement of the cytoplasm that could be detected using PIV analysis.

Conclusion(s):
The occurrence and frequency of cytoplasmic Ca2+ oscillations, a critical parameter in activating human zygotes, can be monitored by PIV analysis of cytoplasmic movements. This simple method provides a novel, noninvasive approach to determine in real time the occurrence and frequency of Ca2+ oscillations in human zygotes.

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