Embryo-scale reverse genetics at single-cell resolution

Area of Science:

• Developmental Biology
• Genomics
• Cell Biology

Background:

• Single-cell transcriptomic technologies have advanced cellular atlas generation from whole embryos.
• Existing atlases often lack data on developmental variation across individual embryos.
• Understanding latent variation is crucial for a complete picture of development.

Purpose of the Study:

• To create a comprehensive single-cell transcriptomic atlas of perturbed zebrafish embryos.
• To analyze developmental variation and genetic dependencies across a large number of individual embryos.
• To identify novel cell populations and developmental trajectories influenced by genetic perturbations.

Main Methods:

• Generated single-cell transcriptomic data from 1,812 individually resolved zebrafish embryos.
• Covered 19 timepoints and 23 genetic perturbations, totaling 3.2 million cells.
• Employed high replication (≥8 embryos/condition) to estimate variance and detect deviations.

Main Results:

• Detected perturbation-dependent cell type composition changes relative to wild-type embryos.
• Resolved developmental trajectories and genetic dependencies in rare cranial ganglia neurons (<1% of embryo).
• Identified brachyury-independent cells with notochord sheath cell transcriptomes, suggesting new skull development origins.

Conclusions:

• Standardized, high-resolution, organism-scale single-cell data is key for mapping genetic dependencies in zebrafish.
• This atlas addresses developmental genetics challenges, including cellular and transcriptional plasticity.
• The findings provide new hypotheses for early skull development and individual phenotypic diversity.