To preserve the superior genetic resources and restore the endangered species, Somatic cell nuclear transfer (SCNT) has been used widely. In Korea, the research of dog cloning has made outstanding achievements including the production of the world`s first cloned dog. Sapsaree (Sapsalgae), the representative dog of Gyeongsan-si was designated as a Korea natural monument (No. 368). This male dog used in this study has azoospermia due to unknown cause. In this study, the aim was to confirm the cause of infertility in the cell donor dog and to evaluate the reproduction potential of dog cloning using infertile male dog by SCNT. First, to confirm the infertility of the cell donor dog, the reproductive history and the testis were evaluated. The breeding histology was not recorded in individual document. In histopathology, the Sertoli cell tumor was confirmed in biopsy of the cell donor dog after death. But, these tumors are predominantly in older dogs. Second, we produced the cloned dogs with the somatic cells of the infertile dog and the appearance was similar with the cell donor dog. Also, microsatellite analysis confirmed the genetic relationship between the cell donor and clone dogs. Third, the potential breeding capacity of the cloned dog was confirmed. In T4 assay, the normal dog (same age with cloned dogs), cell donor dog, and cloned dogs was investigated. The cell donor dog with azoospermia had very low T4 level, and cloned dogs showed higher level of T4 than normal dogs. In CASA, There was no significant difference in sperm motor ability between normal dogs and cloned dogs. As a result, cloned dogs produced by SCNT had no problem regarding the reproductive function of the testis. In AI experiment, the semen of clone dogs was used to fertilize a natural female bitch and was diagnosed pregnancy by ultrasonography. In total, 7 puppies were born by normal delivery (male: 3, female: 4). In conclusion, this study confirmed that the reproduction problem of non-genetic infertility can generate a normal descendant by SCNT. Also, the first successful research to restore infertile dogs was completed. Furthermore, SCNT would be useful for the restoration of endangered species and application of superior traits.

Homogeneous microstructures of the PM compacts are difficult to attain when mixed elemental powders are used. This study examined the microstructures of pressed-and-sintered and MIM products that contain Ni and Mo.Ni-rich areas, which were lean in carbon and were soft and were found easily in regular specimens. Gaps or cracks near the Ni-rich or Mo-rich areas were also frequently observed. This problem worsened when Ni and Mo particles were large and were irregular in shape. By using ball milling treatment and ferroalloy powders, the microstructure homogeneity and mechanical properties were improved. The addition of 0.5wt%Cr further improved the distribution of Ni because Cr reduced the repulsion effect between nickel and carbon. With the elimination of Ni-rich areas, more bainites and martensites were formed and mechanical properties were significantly improved.