MG132 treatment during oocyte maturation improves embryonic development after somatic cell nuclear transfer and alters oocyte and embryo transcript abundance in pigs

Assessment of the Growth and Reproductive Performance of Cloned Pietrain Boars

How to maximize the use of the genetic merits of the high-ranking boars (also called superior ones) is a considerable question in the pig breeding industry, considering the money and time spent on selection. Somatic cell nuclear transfer (SCNT) is one of the potential ways to answer the question, which can be applied to produce clones with genetic resources of superior boar for the production of commercial pigs. For practical application, it is essential to investigate whether the clones and their progeny keep behaving better than the "normal boars", considering that in vitro culture and transfer manipulation would cause a series of harmful effects to the development of clones. In this study, 59,061 cloned embryos were transferred into 250 recipient sows to produce the clones of superior Pietrain boars. The growth performance of 12 clones and 36 non-clones and the semen quality of 19 clones and 28 non-clones were compared. The reproductive performance of 21 clones and 25 non-clones were also tested. Furthermore, we made a comparison in the growth performance between 466 progeny of the clones and 822 progeny of the non-clones. Our results showed that no significant difference in semen quality and reproductive performance was observed between the clones and the non-clones, although the clones grew slower and exhibited smaller body size than the non-clones. The F1 progeny of the clones showed a greater growth rate than the non-clones. Our results demonstrated through the large animal population showed that SCNT manipulation resulted in a low growth rate and small body size, but the clones could normally produce F1 progeny with excellent growth traits to bring more economic benefits. Therefore, SCNT could be effective in enlarging the merit genetics of the superior boars and increasing the economic benefits in pig reproduction and breeding.

Effect of addition of FSH, LH and proteasome inhibitor MG132 to in vitro maturation medium on the developmental competence of yak (Bos grunniens) oocytes

BACKGROUND

The competence for embryonic development after IVF is low in the yak, therefore, we investigated the effects of supplementation of FSH, LH and the proteasome inhibitor MG132 in IVM media on yak oocyte competence for development after IVF.

METHODS

In Experiment 1, yak cumulus-oocyte complexes (COCs) were in vitro matured (IVM) in TCM-199 with 20% fetal calf serum (FCS), 1 microg/mL estradiol-17beta, and different combinations of LH (50 or 100 IU/mL) and FSH (0, 1, 5, 10 microg/mL) at 38.6 degrees C, 5% CO2 in air for 24 h. Matured oocytes were exposed to frozen-thawed, heparin-capacitated yak sperm. Presumptive zygotes were cultured in SOF medium containing 6 mg/ml BSA, 0.5 mg/mL myoinositol, 3% (v/v) essential amino acids, 1% nonessential amino acids and 100 μg/mL L-glutamine (48 h, 38.5 degrees C, 5% CO2, 5% O2, and 90% N2). In Experiment 2, cumulus cells were collected at the end of IVM to determine FSHR and LHR mRNA expression by real-time PCR. In Experiment 3 and 4, COCs were cultured in the presence or absence of the proteasomal inhibitor MG132 from either 0-6 h or 18-24 h after initiation of maturation.

RESULTS

The optimum concentration of FSH and LH in IVM media was 5 microg/mL FSH and 50 IU/mL LH which resulted in the greatest cleavage (79.1%) and blastocyst rates (16.1%). Both FSHR and LHR mRNA were detected in yak cumulus cells after IVM. Treatment with MG132 early in maturation reduced (P<0.05) cleavage and blastocyst rates. Conversely, treatment with MG132 late in maturation improved (P<0.05) blastocyst rate. Optimal results with MG132 were achieved at a concentration of 10 microM.

CONCLUSIONS

An optimum concentration of FSH and LH in IVM medium, and treatment with MG132 late in maturation can improve yak oocytes competence for development after IVF.

Genetic polymorphisms, growth performance, hematological parameters, serum enzymes, and reproductive characteristics in phenotypically normal Landrace boars produced by somatic cell nuclear transfer

Understanding the performances of cloned pigs and their offspring is critical to evaluate the practical applications of somatic cell nuclear transfer. In this study, genetic polymorphism, growth performance, hematological parameters, and reproduction characteristics of cloned Landrace boars were compared with those of controls. In addition, the growth performance of clone offspring was also evaluated. A total of 479 reconstructed embryos were transferred to five recipient pigs and resulted in the delivery of 14 piglets (overall cloning of 2.9%) from two litters. Analyses of microsatellite markers and polymorphisms of the specific genes confirmed that the 14 clones were genetically identical to the nuclear donor and maintained the desirable genotypes. Growth performance of five healthy, phenotypically normal cloned boars from one litter and eight of their male offspring did not differ from age, breed, and management-matched controls. Although some significant differences were observed between cloned and control boars in hematological and serum enzymes, most of these parameters were within the normal range. Cloned boars had less (P < 0.05) normal sperm in the ejaculated boars than in control boars (71.4% vs. 77.9%, respectively), but sperm production (ejaculate volume, sperm concentration, and total sperm) did not differ between these groups. In addition, use of frozen-thawed semen from cloned boars for insemination produced results that seemed comparable to a control. In conclusion, the present study reported that somatic cell nuclear transfer is effective in reproducing preferred genetic traits and has potential applications to conserve elite bloodlines in a routine pig breeding program.

Treatment with the proteasome inhibitor MG132 during the end of oocyte maturation improves oocyte competence for development after fertilization in cattle

Maturation of the oocyte involves nuclear and cytoplasmic changes that include post-translational processing of proteins. The objective was to investigate whether inhibition of proteasomes during maturation would alter competence of the bovine oocyte for fertilization and subsequent development. Cumulus-oocyte complexes were cultured in the presence or absence of the proteasomal inhibitor MG132 from either 0-6 h or 16-22 h after initiation of maturation. Treatment with MG132 early in maturation prevented progression to meiosis II and reduced fertilization rate and the proportion of oocytes and cleaved embryos that became blastocysts. Conversely, treatment with MG132 late in maturation improved the percentage of oocytes and cleaved embryos that became blastocysts without affecting nuclear maturation or fertilization rate. Optimal results with MG132 were achieved at a concentration of 10 µM - effects were generally not observed at lower or higher concentrations. Using proteomic analysis, it was found that MG132 at the end of maturation increased relative expression of 6 proteins and decreased relative expression of 23. Among those increased by MG132 that are potentially important for oocyte competence are GAPDH, involved in glycolysis, TUBA1C, needed for organellar movement, and two proteins involved in protein folding (P4HB and HYOU1). MG132 decreased amounts of several proteins that exert anti-apoptotic actions including ASNS, HSP90B1, PDIA3 and VCP. Another protein decreased by MG132, CDK5, can lead to apoptosis if aberrantly activated and one protein increased by MG132, P4HB, is anti-apoptotic. Finally, the pregnancy rate of cows receiving embryos produced from oocytes treated with MG132 from 16-22 h of maturation was similar to that for control embryos, suggesting that use of MG132 for production of embryos in vitro does not cause a substantial decrease in embryo quality.