CRISPR-Cas9 基因剪切机制图

生成一张 4:5 竖版「CRISPR-Cas9 基因剪切机制图」案例图，所属分类为「科研与学术图」。Cas9 蛋白夹住 DNA 螺旋与 sgRNA 结合的扁平示意图，标注双链断裂位点与颜色图例。画面需要完整呈现上述主体、构图、配色、材质、光线和整体风格；可见文字以自然简体中文为主，必要的技术缩写、代码、变量名、学术符号、单位、拉丁物种名或装饰性外文可保留。

A clean Nature-journal-style flat illustration of the CRISPR-Cas9 gene-editing mechanism. Center composition: a double-stranded DNA helix shown in cross-section with a Cas9 protein complex (shown as a grey molecular clamp) bound to a guide RNA strand (orange ribbon). The PAM site is highlighted with a pale-yellow callout box labeled "PAM". A cut is shown mid-strand with blunt ends separated and labeled "DSB (double-strand break)". A small legend in the lower-right identifies color codes: blue = DNA template strand, teal = non-template strand, orange = sgRNA, grey = Cas9. White background, CMYK-safe palette, thin 1 pt stroke lines, sans-serif 9 pt labels. Arrows indicate cleavage direction. Overall layout matches a textbook figure panel with a subtle drop shadow on the protein complex.