Journal: Poultry Science
Article Title: High genotoxicity of CRISPR/Cas9 versus limited efficacy of CRISPRi in chicken primordial germ cells
doi: 10.1016/j.psj.2026.106722
Figure Lengend Snippet: CRISPR/Cas9 shows high editing efficiency in PGCs. (A) Phase-contrast images of cultured PGCs isolated from embryonic blood, showing typical colony morphology after 3 weeks in vitro . Left: male PGC colony; right: female PGC colony. Scale bar = 20 µm. (B) Immunofluorescence for germ cell markers in PGCs. These cells (male line shown) strongly express SSEA-1 (green, cell surface) and VASA/DDX4 (red, cytoplasm), even after long-term culture (>50 days). Nuclei are counterstained with DAPI (blue). Scale bar = 5 µm. (C) Representative fluorescence microscopy of EGFP + PGCs 5 days after co-electroporation with Cas9 and sgRNAs targeting EGFP (gEGFP1+2). Left: cells electroporated with Cas9 mRNA at 1 µg, 2 µg, or 3 µg (with constant gRNA amount). Right: cells electroporated with Cas9 protein (RNP complex) at equivalent molar doses (1:1.2 Cas9:sgRNA ratio). In both mRNA and protein conditions, higher Cas9 doses result in loss of EGFP fluorescence and reduced cell numbers (rounding and death) compared to lower doses. Scale bar = 20 µm. (D) Flow cytometry analysis of EGFP fluorescence and cell viability in edited versus control PGCs. Left: histogram overlays of EGFP intensity for control (untreated EGFP + PGCs, gray) vs. CRISPR-edited cells (green). Cas9-edited populations shift toward lower fluorescence, indicating EGFP knockout. Upper right: bar graph quantifying the percentage of EGFP + cells in each group (mean ± SEM, n = 3). Both Cas9 mRNA and Cas9 protein treatments caused a dose-dependent decrease in the fraction of EGFP-expressing cells compared to control (p-values are indicated in the figure by one-way ANOVA). Lower right: plot showing the percentage of live cells recovered during flow cytometry. Higher Cas9 doses correlate with reduced live-cell recovery, reflecting CRISPR-induced cytotoxicity in PGCs. Statistical significance was determined by one-way ANOVA (p-values are indicated in the figure).
Article Snippet: The amplicons were subjected to Sanger sequencing, and sequencing traces were analyzed using the Inference of CRISPR Edits (ICE) software tool (v3.0, Synthego).
Techniques: CRISPR, Cell Culture, Isolation, In Vitro, Immunofluorescence, Fluorescence, Microscopy, Electroporation, Flow Cytometry, Control, Knock-Out, Expressing, Cell Recovery