A technique to collect large numbers of worm embryos, all precisely the same age, is reported online this week in Nature Methods. It will allow for detailed studies of early events during embryogenesis.
The worm Caenorhabditis elegans is a popular animal model for biologists, and many genes essential for the early events in embryo development have been identified. Yet, to date, it has not been possible to collect large numbers of embryos at the same developmental stage, a prerequisite to studying gene expression and protein interactions on a genome-wide scale. The current method of choice is collecting the embryos by hand, which is time consuming and does not yield adequate sample size for large-scale studies.
Nikolaus Rajewsky and colleagues improve the process using fluorescence-activated cell sorting (FACS). They create embryos that express a stage-specific protein fused to a fluorescent marker; when the embryo reaches the particular stage, it fluoresces. This is an ideal way to rapidly collect tens of thousands of embryos at the same stage.
Making use of this technique, the scientists carried out high-throughput sequencing to profile small RNA populations in embryos, and gained insight into how gene expression changes during the first cell cycles in a worm embryo.