Ca2+ dynamics in oocytes from naturally-aged mice
Jenna Haverfield1, Shoma Nakagawa1, Daniel Love2, Elina Tsichlaki3, Michail Nomikos2, F. Anthony Lai2, Karl Swann2 & Greg FitzHarris1,3
- Centre Recherche Centre Hospitalier Université de Montréal, Montreal, Québec, H2X 0A9, CanadA, Department of Obstetrics and Gynaecology, University of Montréal, Montréal, Québec, H3T 1J4, Canada
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, CF14 4XN, UK
- Department of Cell and Developmental Biology, University College London, WC1E 6BT, London, UK
Abstract
The ability of human metaphase-II arrested eggs to activate following fertilisation declines with advancing maternal age. Egg activation is triggered by repetitive increases in intracellular Ca2+ concentration ([Ca2+]i) in the ooplasm as a result of sperm-egg fusion. We therefore hypothesised that eggs from older females feature a reduced ability to mount appropriate Ca2+ responses at fertilisation. To test this hypothesis we performed the first examination of Ca2+ dynamics in eggs from young and naturally-aged mice. Strikingly, we find that Ca2+stores and resting [Ca2+]i are unchanged with age. Although eggs from aged mice feature a reduced ability to replenish intracellular Ca2+ stores following depletion, this difference had no effect on the duration, number, or amplitude of Ca2+ oscillations following intracytoplasmic sperm injection or expression of phospholipase C zeta. In contrast, we describe a substantial reduction in the frequency and duration of oscillations in aged eggs upon parthenogenetic activation with SrCl2. We conclude that the ability to mount and respond to an appropriate Ca2+ signal at fertilisation is largely unchanged by advancing maternal age, but subtle changes in Ca2+ handling occur that may have more substantial impacts upon commonly used means of parthenogenetic activation.
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Publisher: Haverfield et al., Sci Rep. 2016; 6: 19357
Full text links: https://rdcu.be/cnzxd