MEMOIR: A Novel System for Neural Lineage Tracing

Principle of MEMOIR system. A In MEMOIR system, three types of elements are integrated into the genome, including a Cas9 variant, a set of barcoded scratchpads and a specifically inducible gRNA targeting the scratchpad. Barcoded scratchpads can be collapsed irreversibly by Cas9/gRNA. An inducible degron modulates Cas9 activity. Inverted black triangles in (A) indicate piggyBac terminal repeats. B Schematic of the MEMOIR working in cells: During cell proliferation, stochastic collapsed scratchpads accumulate gradually. Subsequently, single mRNA molecules can be tested with scratchpad-specific probes (green, inset), and a set of barcode-specific probes (purple, pink, inset) through sequential circles of hybridization and imaging