摘要
      超声允许在比光学方法更大的深度成像，但现有的用于体内细胞成像的基因编码声学报告子由于灵敏度、特异性和体内表达差而受到限制。在这里，我们描述了两个声学报告基因（ARGs），一个用于细菌，另一个用于哺乳动物细胞，通过对来自不同细菌和古菌的候选囊泡基因簇的系统发育筛选进行鉴定，这些基因簇提供更强的超声对比，产生可与背景组织区分的非线性信号，并具有稳定的长期表达。与第一代ARG相比，这些改进的细菌和哺乳动物ARG分别产生9倍和38倍强的非线性对比。利用这些新的ARG，我们对肿瘤原位定植和肿瘤归巢治疗细菌中的基因表达进行了非侵入性成像，跟踪了乳腺癌小鼠模型中肿瘤基因表达和生长的进展，并对一个遗传镶嵌肿瘤进行了基因表达引导的针式活检，证明了在厘米深度无创访问动态生物过程。
Abstract
Ultrasound allows imaging at a much greater depth than optical methods, but existing genetically encoded acoustic reporters for in vivo cellular imaging have been limited by poor sensitivity, specificity and in vivo expression. Here we describe two acoustic reporter genes (ARGs)—one for use in bacteria and one for use in mammalian cells—identified through a phylogenetic screen of candidate gas vesicle gene clusters from diverse bacteria and archaea that provide stronger ultrasound contrast, produce non-linear signals distinguishable from background tissue and have stable long-term expression. Compared to their first-generation counterparts, these improved bacterial and mammalian ARGs produce 9-fold and 38-fold stronger non-linear contrast, respectively. Using these new ARGs, we non-invasively imaged in situ tumor colonization and gene expression in tumor-homing therapeutic bacteria, tracked the progression of tumor gene expression and growth in a mouse model of breast cancer, and performed gene-expression-guided needle biopsies of a genetically mosaic tumor, demonstrating non-invasive access to dynamic biological processes at centimeter depth.

https://www.nature.com/articles/s41587-022-01581-y