Background:. The pig is an economically important food source, amounting to approximately 40% of all meat consumed worldwide. Pigs also serve as an impo

The purpose of the present study was to improve cryotolerance using high hydrostatic pressure (HHP) pretreatment of porcine in vitro matured (IVM) oocytes, to facilitate their further developmental competence after parthenogenetic activation. A total of 1668 porcine IVM oocytes were used in our present study. The pressure tolerance and optimal duration of recovery after HHP treatment were determined. Oocytes were treated with either 20 or 40 MPa (200 and 400 times greater than atmospheric pressure) for 60 min, with an interval of 10, 70, and 130 min between pressure treatment and subsequent vitrification under each pressure parameter. Oocytes from all vitrification groups had much lower developmental competence than fresh oocytes (P<0.01) measured as cleavage and blastocyst rates. However, significantly higher blastocyst rates (P<0.01) were obtained in the groups of 20 MPa pressure, with either 70 (11.4±2.4%) or 130 (13.1±3.2%) min recovery, when compared with the vitrification control group without HHP treatment where no blastocysts were obtained. The influence of temperature at HHP treatment on further embryo development was also investigated. Treatments of 20 MPa with 70 min recovery were performed at 37 °C or 25 °C. Oocytes pressurized at 37 °C had a significantly higher blastocyst (14.1±1.4%) rate than those treated at 25 °C (5.3±1.1%; P<0.01). Our results demonstrate that HHP pretreatment could considerably improve the developmental competence of vitrified pig in vitro matured (IVM) oocytes. The HHP pretreatment will be tested as a means to improve survival and developmental competence at different developmental stages in different species including humans. Abstract The purpose of the present study was to improve cryotolerance using high hydrostatic pressure (HHP) pretreatment of porcine in vitro matured (IVM) oocytes, to facilitate their further developmental competence after parthenogenetic activation. A total of 1668 porcine IVM oocytes were used in our present study. The pressure tolerance and optimal duration of recovery after HHP treatment were determined. Oocytes were treated with either 20 or 40 MPa (200 and 400 times greater than atmospheric pressure) for 60 min, with an interval of 10, 70, and 130 min between pressure treatment and subsequent vitrification under each pressure parameter. Oocytes from all vitrification groups had much lower developmental competence than fresh oocytes (P<0.01) measured as cleavage and blastocyst rates. However, significantly higher blastocyst rates (P<0.01) were obtained in the groups of 20 MPa pressure, with either 70 (11.4±2.4%) or 130 (13.1±3.2%) min recovery, when compared with the vitrification control group without HHP treatment where no blastocysts were obtained. The influence of temperature at HHP treatment on further embryo development was also investigated. Treatments of 20 MPa with 70 min recovery were performed at 37 °C or 25 °C. Oocytes pressurized at 37 °C had a significantly higher blastocyst (14.1±1.4%) rate than those treated at 25 °C (5.3±1.1%; P<0.01). Our results demonstrate that HHP pretreatment could considerably improve the developmental competence of vitrified pig in vitro matured (IVM) oocytes. The HHP pretreatment will be tested as a means to improve survival and developmental competence at different developmental stages in different species including humans.

Production of transgenic animals via somatic cell nuclear transfer (SCNT) has been adapted worldwide, but this application is somewhat limited by its relatively low efficiency. In this study, we used handmade cloning (HMC) established previously to produce transgenic pigs that express the functional nematode fat-1 gene. Codon-optimized mfat-1 was inserted into eukaryotic expression vectors, which were transferred into primary swine donor cells. Reverse transcriptase PCR (RT-PCR), gas chromatography, and chromosome analyses were performed to select donor clones capable of converting n-6 into n-3 fatty acids. Blastocysts derived from the clones that lowered the n-6/n-3 ratio to approximately 1:1 were transferred surgically into the uteri of recipients for transgenic piglets. By HMC, 37% (n=558) of reconstructed embryos developed to the blastocyst stage after 7 days of culture in vitro, with an average cell number of 81±36 (n=14). Three recipients became pregnant after 408 day-6 blastocysts were transferred into four naturally cycling females, and a total of 14 live offspring were produced. The nematode mfat-1 effectively lowered the n-6/n-3 ratio in muscle and major organs of the transgenic pig. Our results will help to establish a reliable procedure and an efficient option in the production of transgenic animals.

DNA editing techniques for targeted genome modification have witnessed remarkable advances and been widely used in various organisms. However, traditional gene targeting and cloning method has been shown to be low efficient, time-consuming and expensive for generating knockout animals, especially for big animals. Here we report the generation of site-specific genome modified pig with the newly developed artificially engineered sequence-specific endonucleases (transcription activator-like effector nuclease, TALENs) and handmade cloning (HMC) methods. First, we constructed the porcine GHR-knockout vector according to TALENs kit protocol. To obtain the nuclear donor, the fetal fibroblast cell of Bama (BM) pig were transfected with GHR-knockout vector in G418 selection medium. We collected 173 cell for further positive identification which showed that 46.2% (78/173) of the clones were GHR-knockout cell strains. We chose one bi-allelic knockout cell strain as nuclear donor to produce reconstructed embryos by HMC. It was shown that the blastocyst rate was 43.5% at the 6(th) day in vitro, then 654 HMC-blastocysts were transplanted to uterus of six recipient sows. Finally, a total of 10 live offspring were delivered including 7 bi-allelic knockout piglets. Fibroblasts were obtained from ear biopsies for GHR knockout detection. The body weight of the piglets was measured consecutively, and it was found that the GHR(-)(/)(-) pigs were only 50% smaller than that of the controls at the 20(th) week. In conclusion, our results indicate that TALENs and HMC technology can rapidly and efficiently produce knockout animals for agricultural and biomedical research.