Single-cell transcriptomics has sensitivity limits that restrict low abundance transcript identification, affects clustering and introduce artefact. Here, we describe Constellation DropSeq (C-DropSeq), a molecular transcriptome filter that delivers two orders of magnitude sensitivity gains by maximising read utility while reducing sequencing depth and costs. The simple and powerful method is broadly compatible with library preparation routines and was demonstrated by identifying and characterizing the activation of rare dendritic cell sub-populations.
MainThe dramatic uptake and expansion of single-cell transcriptome analysis tools has transformed biological research, enabling reconstruction of population architectures and underlying processes to be revealed. The tools rely on compartmentalisation of single cells with the introduction of unique genetic barcodes during library preparation 1 . Though formidable, not unexpectedly these methods have sensitivity limits, with associated transcript absence events (dropouts) that restrict the faithful delineation of cell subtypes and especially overlook low abundant transcripts such as transcription factors, receptors and signalling molecules that are often pivotal for accurately describing cell processes and fate 2,3 . This is a consequence of high abundance transcripts occupying the available NGS read space and exacerbated by exponential PCR-directed library preparation routines.Targeted approaches forgo global transcriptome screens, preferring to select transcripts of known utility and are especially favoured for mechanistic studies. Diverse targeted strategies have emerged; physical recovery of transcriptome subsets 4 , coupling custom primers to poly(dT) capture beads (DART-seq) 5 and panel selection by PCR as with the Rhapsody workflow (BD) 6 . These methods are technically challenging and introduce substantial costs. Here, we describe Constellation DropSeq (C-DropSeq), a remarkably simple, inexpensive and scalable (e.g. >200 targets) approach, introducing a linear amplification stage in advance of conventional library preparation. Superior performance is