Energy substrate influences the effect of the timing of the first embryonic cleavage on the development of in vitro‐produced porcine embryos in a sex‐related manner

Abstract

In vitro culture conditions and certain events during the earliest stages of development are linked to embryonic survival, possibly in a sex-related manner. In vitro-produced (IVP) porcine embryos cultured with glucose (IVC-Glu) or pyruvate-lactate (IVC-PL) were tested for any relationship between the timing of the first embryonic cleavage and development and sex ratio. The embryos were assigned to IVC-Glu or IVC-PL groups and classified depending on the timing of their first cleavage: 24, 26, 30, and 48 hr post-insemination (hpi). They were cultured separately in vitro and evaluated for cleavage rate and pattern, blastocyst rate and stage, cell number, apoptosis, and sex ratio. Regardless of energy source, the percentage of two-cell stage and fragmented embryos at the time of their first cleavage was, respectively, higher and lower in early-cleaving embryos. Those embryos cleaved by 24 hpi developed to blastocysts at a higher rate (IVC-Glu: 37.90 ± 3.06%; IVC-PL: 38.73 ± 4.08%) than those cleaved between 30 and 48 hpi (IVC-Glu: 5.87 ± 3.02%; IVC-PL: 8.41 ± 3.50%). Furthermore, a shift toward males was seen among embryos first cleaved before 30 hpi, versus towards females among those cleaved later. The early-cleaving embryos, only from the IVC-PL group, had a higher proportion of expanded blastocysts (81.05 ± 6.54% vs. 13.33 ± 13.33%) with higher cell numbers than their late-cleaving counterparts. Moreover, a shift toward males only appeared at the blastocyst stage in IVC-PL embryos. These findings confirm that the timing of the first cleavage influences development of IVP porcine embryos in a sex-related manner, and it depends on the main energy source of the in vitro culture medium.

Exposure of pregnant sows to low doses of estradiol-17β impacts on the transcriptome of the endometrium and the female preimplantation embryos†

“…Most studies used in vitro produced embryos depicting more often a faster development of male embryos, but this also seems to depend on the culture conditions. For example, in the pig, the energy substrate has been demonstrated to be important in this respect [81].…”

Zygote injection of CRISPR/Cas9 RNA successfully modifies the target gene without delaying blastocyst development or altering the sex ratio in pigs

“…In the pig, embryos that cleaved before 30 hours tended to be males while later cleaving embryo shifted to female in a NCSU23 medium modified to be pyruvate-lactase based (Petters and Wells 1993; Torner et al 2013). The embryos used in this experiment were cultured in an arginine optimized pyruvate, lactate, glutamine based PZM3 medium, MU1 (Redel et al 2015; Yoshioka et al 2002) and cultured in MU2 (Spate et al 2015).…”

Applications of omics and nanotechnology to improve pig embryo production in vitro

“…Furthermore, transcriptional profiling of porcine blastocysts cultured in low (5%) versus high, or atmospheric (20%) oxygen revealed that abundance of SLC2A2 , a high‐capacity glucose transporter, was increased which may explain this metabolic shift (Redel et al, ). Culture with pyruvate and lactate as the primary energy sources has been shown to increase blastocyst rates and total cell numbers, but a bias toward development of male embryos has also been observed (Kim et al, ; Torner, Bussalleu, Briz, Yeste, & Bonet, ; Torner, Bussalleu, Briz, Yeste, & Bonet, ). Currently, two formulations of porcine embryo culture media are predominantly utilized: NCSU‐23 and porcine zygote medium (PZM) variants (Canovas et al, ; Chen et al, ; Petters & Wells, ; Redel et al, ; Spate, Brown, Redel, Whitworth, & Prather, ; Suzuki, Yoshioka, Sakatani, & Takahashi, ; Yoshioka et al, ).…”

“…Furthermore, transcriptional profiling of porcine blastocysts cultured in low (5%) versus high, or atmospheric (20%) oxygen revealed that abundance of SLC2A2, a high-capacity glucose transporter, was increased which may explain this metabolic shift . Culture with pyruvate and lactate as the primary energy sources has been shown to increase blastocyst rates and total cell numbers, but a bias toward development of male embryos has also been observed (Kim et al, 2004;Torner, Bussalleu, Briz, Yeste, & Bonet, 2013;Torner, Bussalleu, Briz, Yeste, & Bonet, 2014).…”