Zinc-finger nickases (ZFNickases) are a type of programmable nuclease that can be engineered from zinc-finger nucleases to induce site-specific single-strand breaks or nicks in genomic DNA, which result in homology-directed repair. Although zinc-finger nuclease-mediated gene disruption has been demonstrated in pigs and cattle, they have not been used to target gene addition into an endogenous gene locus in any large domestic species. Here we show in bovine fetal fibroblasts that targeting ZFNickases to the endogenous β-casein (CSN2) locus stimulates lysostaphin gene addition by homology-directed repair. We find that ZFNickase-treated cells can be successfully used in somatic cell nuclear transfer, resulting in live-born gene-targeted cows. Furthermore, the gene-targeted cows secrete lysostaphin in their milk and in vitro assays demonstrate the milk’s ability to kill Staphylococcus aureus. Our success with this strategy will facilitate new transgenic technologies beneficial to both agriculture and biomedicine.

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Rockburst is a violent rock failure process which poses a significant threat to human safety in mining and tunneling construction. Although many in situ investigations provided valuable insights on the rockburst mechanism, the failure and rock fragmentation process during a rockburst cannot be fully examined on the site. In this paper, a modified triaxial rock testing apparatus is employed to investigate the rockburst behavior of oriented sandstone. A high-speed camera is used to record the crack propagation and the ejection of rock fragments on the unloading surface. The microscopic characteristics of the fragments generated from the rockburst tests are observed using the scanning electron microscope (SEM) imaging technique. The trajectory sketches are drawn to calculate the initial velocities of the rock fragments ejected based on the photographs taken by the high-speed camera. The results show that the mass and velocity of fragments are the two main parameters for the identification of the energytransferring process in the rockburst test. When the bedding orientation is perpendicular to the unloading surface, the rockburst is controlled by the specimen's strength. However, when the bedding orientation is parallel to the unloading surface, the rockburst is dependent on the structural stability of the specimen.