Greenslade, J. E. | Search bioRxiv

bioRxiv2026

Single-cell chromatin profiling reveals dynamic regulatory logic and enhancer elements in brain and retina development

Cell type identity in the nervous system is encoded within cis-regulatory landscapes that integrate transcription factor activity with chromatin accessibility. However, how these regulatory programs are organized and remodeled during post-embryonic neural development is poorly understood. We generate a temporally resolved single-cell chromatin accessibility atlas of [~]95,000 zebrafish brain and retina nuclei spanning larval, juvenile, and adult stages. We define 212 discrete chromatin states and uncover widespread, cell type-specific chromatin reorganization across development. By integrating with transcriptomic data, we link motif accessibility to transcription factor expression and identify regulatory programs that are either maintained or reconfigured during post-embryonic development of each neural cell type. Leveraging this atlas, we systematically identify and functionally validate candidate enhancers in vivo. Focusing on the slc1a3b locus in radial glia, we define evolutionarily conserved, compact enhancer modules that act combinatorially to drive gene expression. Together, these findings provide a systems-level framework for decoding neural regulatory logic and enable functional dissection of conserved cis-regulatory programs in the vertebrate nervous system.

developmental biology↗

bioRxiv2024

Barcoding Notch signaling in the developing brain

Developmental signaling inputs are fundamental for shaping cell fates and behavior. However, traditional fluorescent-based signaling reporters have limitations in scalability and molecular resolution of cell types. We present SABER-seq, a CRISPR-Cas molecular recorder that stores transient developmental signaling cues as permanent mutations in cellular genomes for deconstruction at later stages via single-cell transcriptomics. We applied SABER-seq to record Notch signaling in developing zebrafish brains. SABER-seq has two components: a signaling sensor and a barcode recorder. The sensor activates Cas9 in a Notch-dependent manner with inducible control while the recorder accumulates mutations that represent Notch activity in founder cells. We combine SABER-seq with an expanded juvenile brain atlas to define cell types whose fates are determined downstream of Notch signaling. We identified examples wherein Notch signaling may have differential impact on terminal cell fates. SABER-seq is a novel platform for rapid, scalable and high-resolution mapping of signaling activity during development.

developmental biology↗