Sex determination of porcine embryos using a new developed duplex polymerase chain reaction procedure based on the amplification of repetitive sequences

Sexing of pre-implantation ovine embryos through polymerase chain reaction-based amplification of GAPDH, SRY and AMEL genes

The ability to identify the sex of embryo and control of sex ratio has a great commercial importance to livestock industry. Prediction of embryonic sex could be useful in the management decisions of sex selection in breeding programs. Several methods have been attempted to determine the sex but the polymerase chain reaction (PCR)-based sexing method is generally favoured, as it is cost effective, simple and reliable. The aim of the present study was to identify sex of sheep embryos produced in vitro through amplification of glyceraldehyde 3-phosphate dehydrogenase (GAPDH), sex-determining region Y (SRY) and amelogenin genes present in genomic DNA (gDNA) of embryos through PCR. To avoid false interpretation of the result by no amplification of SRY in female embryos, a duplex PCR was approached to amplify combinedly SRY and GAPDH genes. Sex-specific blood was used in PCR as positive control. In vitro sheep embryos were produced as per standardized protocol of laboratory. Sexing of sex-specific blood and in vitro produced embryos were approached though PCR to amplify the respective genes using gDNA present in the sample without its traditional isolation. The accuracy of sex prediction for embryos was 100% by this procedure.

Embryo development and sex ratio of in vitro-produced porcine embryos are affected by the energy substrate and hyaluronic acid added to the culture medium

In the present study, the effects of replacing glucose with pyruvate-lactate and supplementing these in vitro culture (IVC) media with hyaluronic acid (HA) on porcine embryo development and sex ratio were examined. The in vitro-produced (IVP) porcine embryos were cultured in NCSU-23 medium with 0.0, 0.5 or 1.0mgmL(-1) HA, and with either 5.55mM glucose (IVC-Glu) or pyruvate (0.17mM)-lactate (2.73mM) from 0 to 48h post insemination (h.p.i.) and then with glucose from 48 to 168h.p.i. (IVC-PL). Those embryos cultured with IVC-PL had significantly higher blastocyst rates (23.7±1.5%) than those cultured with IVC-Glu (14.27±2.75%). At 1.0mgmL(-1), HA tended to skew the sex ratio of blastocysts towards males in those embryos cultured in IVC-PL, and led to a significant decrease in the blastocyst rate compared with embryos cultured in the presence of 0.5 and 0.0mgmL(-1) HA and IVC-Glu (4.28±0.28% vs 11.01±1.42% and 10.14±2.77%, respectively) and IVC-PL (14.37±1.35% vs 20.96±2.85% and 22.99±1.39%, respectively). In contrast, there were no significant differences in the total cell number per blastocyst or in apoptosis rates. In conclusion, pyruvate and lactate were the preferred energy substrates in the early stages of IVP porcine embryos. Moreover, 1.0mgmL(-1) HA significantly decreased the percentage of blastocyst rates in both the IVC-Glu and IVC-PL groups, but only by a preferential loss of female embryos for those cultured in IVC-PL.

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

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.