Effects of electromagnetic waves on oocyte maturation and embryonic development in pigs.

Our living environment has been full of electromagnetic radiation (EMR) due to the prevailing electronic devices and equipment. Intermediate frequency electromagnetic field (IF-EMF) or waves constitute a significant part of EMR; therefore, an increasing number of household electrical appliances have become a source of IF-EMF, and concerns about IF-EMF on health are gaining more attention. However, little information is available about its impact on female reproductive traits, such as germ cell viability and early embryonic development, particularly at the cellular and molecular levels. In this study, we used porcine oocytes as a model system to explore the effect of IF-EMF at various intensities on the in vitro maturation (IVM) of oocytes and their subsequent embryonic development. Our results showed that no difference in oocyte maturation rates was detected among groups, but the cleavage and blastocyst rates of parthenotes derived from EMF-treated oocytes decreased with the weaker IF-EMF intensity (25 and 50 Gauss) groups compared to the control group (P < 0.05). For cytoplasmic maturation, the weaker IF-EMF intensity groups also showed a peripheral pattern of mitochondrial distribution resembling that of immature oocytes and increased autophagy activity. No obvious differences in cytoskeletal distribution and total cell numbers of blastocysts were investigated in the four IF-EMF treatments compared to those in the control group. Although the underlying mechanism associated with EMF effects on oocytes and embryos is still elusive, we have demonstrated that low intensity IF-EMF exerts harmful effects on porcine oocytes during the maturation stage, carrying over such effects to their subsequent embryonic development.

Complex genomic organization of Indian muntjac centromeric DNA.

A 69-kb Indian muntjac bacterial artificial chromosome (BAC) clone that screened positive for Cervid satellites I and IV was selected for complete sequence analysis and further characterization. The sequences of this BAC clone were found in the centromeres and in some interstitial sites of Indian muntjac chromosomes. Sequence analyses showed that the BAC clone contained a 14.5 kb Cervid satellite I-like DNA element and a 9 kb Cervid satellite IV-like DNA element. In addition, it contained 51 regions each organized in a complex fashion, with sequences homology to intersperse repetitive sequences such as LINEs, SINEs, LTRs, other published DNA elements, and unassigned sequences. The FISH patterns of seven non-satellite sequence elements generated from the BAC clone showed mainly specific to centromeres of the Indian muntjac representing novel centromeric DNAs of the species. Furthermore, FISH signals and Southern blot patterns of these elements suggest the existence of a not yet identified repetitive sequence with giant repeated monomers. Positive FISH signals of these elements were also detected in the centromeric regions of Formosan muntjac. This suggests that these newly identified non-Cervid satellite DNA sequences have been conserved in the centromere of the Formosan muntjac.

Novel histone deacetylase inhibitors and embryo aggregation enhance cloned embryo development and ES cell derivation in pigs.

The histone deacetylase inhibitor (HDACi) has been investigated for treating cancers and many other diseases as well as enhancing the reprogramming efficiency in cloned embryos for decades. In the present study, we investigated the effects of two novel HDAC inhibitors, i.e., HDACi-14 and -79, at the concentrations of 0, 1, 2, or 4 µM on the development of embryos cloned by the oocyte bisection cloning technique (OBCT). Blastocyst rates for the reconstructed embryos reached 60% in the 2 µM HDACi-14-treated groups, which was higher (P < 0.05) compared to the untreated group (36.9%). Similarly, HDACi-79 treatment at 2 and 4 µM also conferred higher (P < 0.05) blastocyst rates than that of the untreated group (79.4, 74.2, and 50.0%, respectively). Both HDACi-14 and -79 treatments had no beneficial effect on total cell numbers and apoptotic indices of cloned embryos (P > 0.05). Histone acetylation profile by both HDACi-14 (2 µM) and -79 (2 µM) treatments demonstrated a drastic increase (P < 0.05) mainly in two-cell stage embryos when compared to the control group. After seeding on the feeder cells, the aggregated cloned blastocysts produced by the HDACi-79 treatment showed a significant increase of primary outgrowths compared to the control group (60.0% vs. 42.9%; P < 0.05). Finally, the cloned embryo-derived ES cell lines from aggregated cloned embryos produced from the HDACi-79-treated, HDACi-14-treated and control groups were established (5, 3, and 2 lines, respectively). In conclusion, the novel histone deacetylation inhibitors improve blastocyst formation and potentially increase the derivation efficiency of ES cell lines from the cloned porcine embryos produced in vitro. Depending on the purposes, some fine-tuning may be required to maximize its beneficial effects of these newly synthesized chemicals.