The pig has been considered to serve as an appropriate model of human disease. Therefore, establishment of porcine embryonic stem cell lines is important. The purpose of the present study was to further work in this direction. We produced porcine parthenogenetic embryos, and separately aggregated two of each of two-cell (2×2), four-cell (2×4), and eight-cell (2×8) embryos derived by parthenogenesis. After culture for 4 days, the developmental ability of the aggregates and total blastocyst cell numbers were evaluated. The percentage of blastocysts was significantly higher in both 2×4- and 2×8-aggregated embryos (58.3±1.9% and 37.2±2.8%, respectively) than in the control or 2×2-aggregated embryos (23.6±1.1% and 12.5±2.4%, respectively). Total blastocyst cell numbers were increased in the 2×4- and 2×8-aggregated embryos (by 44±3.0% and 45±3.3%, respectively) compared with those of control or 2×2-aggregated embryos (30.5±2.1% and 30.7±2.6%, respectively; p<0.05). The levels of mRNA encoding Oct-4 were higher in both the 2×4- and 2×8-aggregated embryos than in the control. When blastocysts derived from 2×4- aggregated embryos or intact normal embryos were cultured on mouse embryonic fibroblast feeder cells to obtain porcine stem cells, blastocysts from aggregated embryos formed colonies that were better in shape compared with those derived from intact blastocysts. Together, the data show that aggregation of porcine embryos not only improves blastocyst quality but also serves as an efficient procedure by which porcine embryonic stem cells can become established.

In order to breed the useful mutants in black raspberry, cultivated in Gochang-gun, leaf-petiol explants from shoot-proliferating culture was regenerated after irradiated with 30, 50 and 70 Gy gamma-ray. The LD50 dose of leaf-petiol explants was identified as 30Gy after two months. Morphological characteristics of the variants were observed such as stem variation, existence and nonexistence of spine, spine color, anthocyanin content, width of leaf, thick of leaf compared with donor cultivar. Of the 701 mutants, 14 lines with the useful mutant characters were selected and random amplified polymorphic DNA(RAPD) was carried out to confirm mutation state at the molecular level with 20 primers. There are many bands be revealed only in mutants and disappear in mutants reversely. RAPD analysis revealed a high level of genetic diversity among Control and mutants. Compared to Control, No. 14 mutant showed the highest genetic diversity. Also, the co-dominant SSR markers have allowed the evaluation of heterozygosity. Valuable mutants obtained will be useful for developing new cultivars and studying gene function in molecular level.