Bob Goldstein | Search bioRxiv

bioRxiv2016

A Transcriptional Lineage of the Early C. elegans Embryo

HIGHLIGHTS- RNA-seq on each cell of the early C. elegans embryo complements the known lineage\n- We measured the zygotic activation specific to each unique cell of the embryo\n- We identified genes that are functionally redundant and critical for development\n- We created an interactive online data visualization tool for exploring the data\n\n\neTOC BLURBC. elegans is a powerful model for development, with an invariant and completely described cell lineage. To enrich this resource, we performed single-cell RNA-seq on each cell of the embryo through the 16-cell stage. Zygotic genome activation is differential between cell types. We identified hundreds of candidates for partially redundant genes, and verified one such set as critical for development. We created an interactive online data visualization tool to invite others to explore our dataset.\n\nSUMMARYDuring embryonic development, cells must establish fates, morphologies and behaviors in coordination with one another to form a functional body. A prevalent hypothesis for how this coordination is achieved is that each cells fate and behavior is determined by a defined mixture of RNAs. Only recently has it become possible to measure the full suite of transcripts in a single cell. Here we quantify the abundance of every mRNA transcript in each cell of the C. elegans embryo up to the 16-cell stage. We describe spatially dynamic expression, quantify cell-specific differential activation of the zygotic genome, and identify critical developmental genes previously unappreciated because of their partial redundancy. We present an interactive data visualization tool that allows broad access to our dataset. This genome-wide single-cell map of mRNA abundance, alongside the well-studied life history and fates of each cell, describes at a cellular resolution the mRNA landscape that guides development.

Developmental Biology↗

bioRxiv2016

Comparative assessment of fluorescent proteins for in vivo imaging in an animal model system

Fluorescent protein tags are fundamental tools used to visualize gene products and analyze their dynamics in vivo. Recent advances in genome editing have enabled precise insertion of fluorescent protein tags into the genomes of diverse organisms. These advances expand the potential of in vivo imaging experiments, and they facilitate experimentation with new, bright, photostable fluorescent proteins. Most quantitative comparisons of the brightness and photostability of different fluorescent proteins have been made in vitro, removed from biological variables that govern their performance in cells or organisms. To address the gap we quantitatively assessed fluorescent protein properties in vivo in an animal model system. We generated transgenic C. elegans strains expressing green, yellow, or red fluorescent proteins in embryos, and we imaged embryos expressing different fluorescent proteins under the same conditions for direct comparison. We found that mNeonGreen was not bright in vivo as predicted based on in vitro data, but that mNeonGreen is a better tag than GFP for specific kinds of experiments, and we report on optimal red fluorescent proteins. These results identify ideal fluorescent proteins for imaging in vivo in C. elegans embryos, and they suggest good candidate fluorescent proteins to test in other animal model systems.

Cell Biology↗