The employment of strontium to activate mouse oocytes: effects on spermatid-injection outcome

Abstract

The present research investigated the effects of various strontium concentrations, in combination with different incubation periods, on mouse parthenogentic oocyte activation and blastocyst development. The results for blastocyst development showed a trend indicating that 10 mM strontium for 3 h was the optimal strontium protocol. Ethanol, an agent that incites oocyte activation via a monotonic rise in calcium, was employed as a control. The outcome of blastocyst formation arising from parthenogenic ethanol activation was significantly less (P < 0.001) than that achieved by the optimal strontium protocol. To assess the impact of strontium oocyte activation on embryo viability following fertilization with immature germ cells, the protocol of 10 mM strontium for 3 h was applied to oocytes injected with round spermatids and then compared with other protocols. The results indicate that following round-spermatid injection the benefits derived from strontium artificial oocyte activation are evident during both pre-and post-implantation development. However, in order to adjust the protocol to the most effective round-spermatid injection in relation to the oocyte cell cycle, injection was done 1.5 h after strontium activation followed by another 1.5 h activation in strontium. The implementation of round-spermatid injection in combination with this oocyte-activation protocol led to live-birth outcomes not significantly different to those outcomes obtained by mature spermatozoa.

Ectopic expression of Fgf3 leads to aberrant lineage segregation in the mouse parthenote preimplantation embryos

“…According to our observation, culturing fertilized oocytes in SrCl 2 -containing medium for the same time as unfertilized (parthenogenetic) oocytes did not affect immunostaining results in these control embryos, indicating that chemical activation by SrCl 2 does not contribute to the differential gene expression between controls and parthenotes. These observations are consistent with many previous reports (Loren and Lacham-Kaplan, 2006;Kyono et al, 2008;Chen et al, 2010).…”

Regulation of endoplasmic reticulum Ca2+ oscillations in mammalian eggs

“…Nevertheless, the precise mechanism whereby these agents promote oscillations or the impact on [Ca 2+ ] ER levels are unknown. We first examined the role of SrCl 2 , because it is widely used to induce artificial activation of mouse eggs following somatic cell nuclear transfer or round spermatid injection (Loren and Lacham-Kaplan, 2006;Wakayama et al, 1998 Fig. 4C; Fig influx also contributes to the robust first [Ca 2+ ] i rise (Halet et al, 2004 (Dumollard et al, 2004;Liu et al, 2001).…”

Parthenogenetic activation of bovine oocytes using single and combined strontium, ionomycin and 6-dimethylaminopurine treatments

“…2 Departamento de Medicina Veterinária Preventiva e Reprodução Animal, FCAV -UNESP, Via de Acesso Prof. Paulo Donato Castellane, s/n, 14884-900, Jaboticabal, SP, Brazil. 3 Departamento de Ciências Básicas, FZEA -USP, Avenida Duque de Caxias Norte, 225, 13635-900, Pirassununga, SP, Brazil. somatic cell nuclear transfer (SCNT; Wells et al, 1999), intracytoplasmic sperm injection (ICSI; Suttner et al, 2000) and round-spermatid injection (ROSI; Loren & Lacham-Kaplan, 2006). Furthermore, activation is used for elucidation of events during early embryonic development (Soloy et al, 1997) and for studies on genomic imprinting (Solter, 1988).…”