Journal: bioRxiv
Article Title: Whole-transcriptome-scale and isoform-resolved spatial imaging of single cells in complex tissues
doi: 10.1101/2025.08.27.672533
Figure Lengend Snippet: (A) Schematic of the RT&T-AMP workflow. Reverse transcription with a polyT primer generates a complementary DNA (cDNA) and adds a short non-templated CCC overhang to the cDNA. A template switching oligo (TSO) containing a T7 promoter sequence and GGG to bind to the CCC overhand allows template switching of the reverse transcriptase to add the T7 promoter to the cDNA. T7 RNA polymerase then transcribes the cDNA into multiple copies of RNA, forming an amplicon. MERFISH encoding probes and fluorescently labeled readout probes are then used to detect the RNA amplicons. (B) smFISH images of an inhibitory neuronal subtype marker Sst in single cells in the mouse brain tissue using probe sets containing 30, 5, and 1 encoding probes with (top) and without (bottom) RT&T-AMP. Scale bars: 10 µm. (C) Left and middle: Two-color smFISH images of Sst from multiple fields of view (FOV) tiled together, showing high co-localization of signals from probes labeled with different fluorescent dyes. Left: detection using 5 encoding probes per gene. Middle: detection using 1 encoding probe per gene. Since each amplicon contains multiple copies of RNA, multiple probes can bind to the same amplicon, allowing colocalization of the differently colored signals. Stray, non-specific binding of probes is unlikely to generate colocalized signal. Right: smFISH image with non-targeting probes (5 probes per gene) yield negligible signal. Bottom panels show the amplified view of the boxed region in the top panels. Scale bars: 10 µm (top), 5 µm (bottom). (D) Percent of cells in the imaged brain sections showing positive Sst signal, detected using 5 encoding probes, 1 encoding probes, and 5 non-targeting probes.
Article Snippet: The DBCO-modified oligo was then labeled with an azide-modified fluorescent dye (Lumiprobe, Cy3b 19330; Sulfo-Cy7 A5330; Alexa Fluor 647 16820).
Techniques: Reverse Transcription, Sequencing, Amplification, Labeling, Marker, Binding Assay