PLCζ can stably regulate Ca²⁺ fluctuations in early embryo

Area of Science:

• Developmental Biology
• Reproductive Science
• Calcium Signaling

Background:

• Phospholipase C zeta (PLCζ) is crucial for initiating calcium (Ca2+) oscillations in mammalian sperm, essential for fertilization.
• Understanding PLCζ's role in early embryonic Ca2+ fluctuations is key to comprehending fertilization and subsequent development.
• Existing methods for oocyte activation, like ionomycin and 6-DMAP, provide a benchmark for evaluating novel approaches.

Purpose of the Study:

• To investigate the influence of sheep Phospholipase C zeta (PLCζ) on early embryonic Ca2+ fluctuations.
• To construct a model of early embryonic Ca2+ fluctuations using PLCζ.
• To compare the effects of PLCζ-mediated activation with ionomycin/6-DMAP on sheep oocyte activation and early embryonic development.

Main Methods:

• Sheep MII oocytes were cultured and screened.
• Microinjection was used to introduce a pEGFP-N1-PLCζ plasmid for oocyte activation in the test group.
• The control group was activated using Ionomycin combined with 6-Dimethylaminopurine (6-DMAP).

Main Results:

• Both PLCζ and ionomycin/6-DMAP successfully induced parthenogenetic activation and early embryonic development in sheep oocytes.
• The ionomycin/6-DMAP group showed significantly higher cleavage rates (76.1% ± 0.7%) and blastocyst rates (21.1% ± 0.92%) compared to the PLCζ group (60.9% ± 19.4% and 16.2% ± 0.62%, respectively).
• PLCζ induced Ca2+ peaks at the cleavage and morula stages, with levels returning to normal by the morula stage, indicating stable regulation. The ionomycin/6-DMAP group exhibited higher and later Ca2+ peaks.

Conclusions:

• PLCζ gene expression promotes stable regulatory effects on Ca2+ fluctuations throughout early embryonic development stages.
• While ionomycin/6-DMAP yields higher developmental rates, PLCζ offers a distinct pattern of Ca2+ signaling potentially important for specific developmental processes.
• This study provides insights into the differential roles of PLCζ and chemical activators in regulating Ca2+ dynamics during early embryogenesis.