title: Ca(2+) dynamics in oocytes from naturally-aged mice.
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 Ca(2+) concentration ([Ca(2+)]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 Ca(2+) responses at fertilisation. To test this hypothesis we performed the first examination of Ca(2+) dynamics in eggs from young and naturally-aged mice. Strikingly, we find that Ca(2+) stores and resting [Ca(2+)]i are unchanged with age. Although eggs from aged mice feature a reduced ability to replenish intracellular Ca(2+) stores following depletion, this difference had no effect on the duration, number, or amplitude of Ca(2+) 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 Ca(2+) signal at fertilisation is largely unchanged by advancing maternal age, but subtle changes in Ca(2+) handling occur that may have more substantial impacts upon commonly used means of parthenogenetic activation.
authors.affiliation: Centre Recherche Centre Hospitalier Université de Montréal, Montreal, Québec, Canada, H2X 0A9.|Department of Obstetrics and Gynaecology, University of Montréal, Montréal, Québec, Canada, H3T 1J4.
authors.forename: Jenna
authors.initials: J
authors.lastname: Haverfield
authors.affiliation: Centre Recherche Centre Hospitalier Université de Montréal, Montreal, Québec, Canada, H2X 0A9.
authors.forename: Shoma
authors.initials: S
authors.lastname: Nakagawa
authors.affiliation: Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, UK, CF14 4XN.
authors.forename: Daniel
authors.initials: D
authors.lastname: Love
authors.affiliation: Department of Cell and Developmental Biology, University College London, London, UK, WC1E 6BT.
authors.forename: Elina
authors.initials: E
authors.lastname: Tsichlaki
authors.affiliation: Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, UK, CF14 4XN.
authors.forename: Michail
authors.initials: M
authors.lastname: Nomikos
authors.affiliation: Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, UK, CF14 4XN.
authors.forename: F Anthony
authors.initials: FA
authors.lastname: Lai
authors.affiliation: Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, UK, CF14 4XN.
authors.forename: Karl
authors.initials: K
authors.lastname: Swann
authors.affiliation: Centre Recherche Centre Hospitalier Université de Montréal, Montreal, Québec, Canada, H2X 0A9.|Department of Obstetrics and Gynaecology, University of Montréal, Montréal, Québec, Canada, H3T 1J4.|Department of Cell and Developmental Biology, University College London, London, UK, WC1E 6BT.
authors.forename: Greg
authors.initials: G
authors.lastname: FitzHarris
mesh_terms: D000367:Age Factors; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D005260:Female; D042541:Intracellular Space; D008297:Male; D051379:Mice; D009865:Oocytes / Q000378:metabolism*; D010063:Ovum / Q000378:metabolism; D020554:Sperm Injections, Intracytoplasmic
chemical_list: D002118:Calcium