CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein) is widely used in the field of livestock breeding. However, its low efficiency, untargeted cutting and low safety have greatly hampered its use for introducing single base mutations in livestock breeding. Single base editing, as a new gene editing tool, can directly replace bases without introducing double strand breaks. Single base editing shows high efficiency and strong specificity, and provides a simpler and more effective method for precise gene modification in livestock breeding. This paper introduces the principle and development of single base editing technology and its application in livestock breeding.
Animals ; Gene Editing ; CRISPR-Cas Systems/genetics* ; Livestock/genetics* ; Mutation ; Technology

【Objective】 To evaluate the safety and efficacy of long-term indwelling of Allium ureteral stent in the treatment of ureteral stricture. 【Methods】 The clinical data of patients who underwent endoscopic Allium ureteral stent implantation for ureteral stricture in our hospital during Aug.2020 and Dec.2022 were retrospectively analyzed, and the surgical conditions and adverse events were recorded. The data of serum creatinine, blood urea nitrogen, glomerular filtration rate (GFR) and renal pelvis width under ultrasound were compared before surgery and 1, 3, 6 and 12 months after surgery. 【Results】 A total of 52 patients with ureteral stricture of 1.1 (0.7, 2.0)cm were included. All operations were successful. The operation time was 82.5 (70, 114)min, intraoperative blood loss 20 (10, 20)mL, and postoperative hospitalization stay 1 (1, 2) day. During the follow-up of (13.2±7.8) months, 14 patients had stent displacement, 5 had stone obstruction of stent tubes, 7 had occasional hematuria after movement, 9 had intermittent lumbar and abdominal pain, and 1 had recurrent urinary tract infection. The serum creatinine, blood urea nitrogen and renal pelvis width of 1 month, 3, 6 and 12 months after surgery were significantly decreased, while GFR was significantly increased. 【Conclusion】 Long-term indwelling of Allium ureteral stent is effective in the treatment of ureteral stricture, but the high incidence of stent displacement should arouse attention.

In this study, a single base editing system was used to edit the FecB and GDF9 gene to achieve a targeted site mutation from A to G and from C to T in Ouler Tibetan sheep fibroblasts, and to test its editing efficiency. Firstly, we designed and synthesized sgRNA sequences targeting FecB and GDF9 genes of Ouler Tibetan sheep, followed by connection to epi-ABEmax and epi-BE4max plasmids to construct vectors and electrotransfer into Ouler Tibetan sheep fibroblasts. Finally, Sanger sequencing was performed to identify the target point mutation of FecB and GDF9 genes positive cells. T-A cloning was used to estimate the editing efficiency of the single base editing system. We obtained gRNA targeting FecB and GDF9 genes and constructed the vector aiming at mutating single base of FecB and GDF9 genes in Ouler Tibetan sheep. The editing efficiency for the target site of FecB gene was 39.13%, whereas the editing efficiency for the target sites (G260, G721 and G1184) of GDF9 gene were 10.52%, 26.67% and 8.00%, respectively. Achieving single base mutation in FecB and GDF9 genes may facilitate improving the reproduction traits of Ouler Tibetan sheep with multifetal lambs.
Animals ; Sheep/genetics* ; Gene Editing ; Tibet ; Mutation ; Phenotype ; Mutagenesis, Site-Directed