Traditional pig breeding has a long cycle and high cost, and there is an urgent need to use new technologies to revitalize the pig breeding industry. The recently emerged CRISPR/Cas9 genome editing technique shows great potential in pig genetic improvement, and has since become a research hotspot. Base editor is a new base editing technology developed based on the CRISPR/Cas9 system, which can achieve targeted mutation of a single base. CRISPR/Cas9 technology is easy to operate and simple to design, but it can lead to DNA double strand breaks, unstable gene structures, and random insertion and deletion of genes, which greatly restricts the application of this technique. Different from CRISPR/Cas9 technique, the single base editing technique does not produce double strand breaks. Therefore, it has higher accuracy and safety for genome editing, and is expected to advance the pig genetic breeding applications. This review summarized the working principle and shortcomings of CRISPR/Cas9 technique, the development and advantages of single base editing, the principles and application characteristics of different base editors and their applications in pig genetic improvement, with the aim to facilitate genome editing-assisted genetic breeding of pig.
Animals ; Swine/genetics* ; Gene Editing ; CRISPR-Cas Systems/genetics* ; DNA Breaks, Double-Stranded

Objective: To establish a quantitative three-dimensional method based on intraoral scan to evaluate the changes of soft tissue, and to evaluate the changes of supracrestal gingival thickness (SGT) in skeletal class Ⅲ patients induced by periodontal regenerative and corticotomy surgery (PRCS). Methods: Twenty-two systematically and periodontally healthy skeletal class Ⅲ patients (4 males and 18 females, aged between 19 and 35 years), who were in need of combined orthodontic-orthognathic treatment and referred to the Department of Periodontology from the Department of Orthodontics and the Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology from January, 2018 to March, 2019, were collected in the study. The teeth involved were 112 anterior teeth (46 maxillary anterior teeth and 66 mandibular anterior teeth). PRCS in anterior tooth area was conducted before orthodontic decompensation. Probing depth (PD), bleeding index (BI) and keratinized gingiva width (KGW) were recorded before surgery and 6 months post-surgery. The intraoral digital impressions of maxillary and mandibular anterior teeth were obtained by 3-shape intraoral scanner before surgery and 6 months after surgery. The Standard Tessellation Language (STL) files were processed using Geomagic qualify 12.2 software to establish the soft tissue morphological measurement model, and to quantitatively analyze the changes of gingival thickness situated 1 to 2 mm apical to the free gingival margin on the median sagittal measurement plane. Results: Probing depth and bleeding index had no significant difference before and 6 months after operation (P>0.05). KGW in 6-month post-operation group [(5.18±2.32) mm] was significantly higher than that in pre-operation group [(4.22±1.43) mm] (P<0.05). Supracrestal gingival thickness situated 1 to 2 mm apical to the free gingival margin also significantly increased 6 months after surgery (P<0.05). The changes of gingival thickness situated 1 to 2 mm apical to the free gingival margin in the upper anterior area were (0.68±0.56) and (1.00±0.69) mm, respectively. The changes in the lower anterior area were (0.38±0.42) and (0.58±0.45) mm, respectively. The gingival changes of the upper anterior teeth were also significantly higher than those of the lower anterior teeth (P<0.01). Conclusions The described quantitative measurement based on intraoral scan could be an effective method for quantitative evaluation of the changes of soft tissue. PRCS could safely increase the supracrestal gingival thickness as well as KGW in skeletal class Ⅲ patients who were in need of combined orthodontic-orthognathic treatment.