Abstract
Visualizing neural-circuit assembly in vivo requires tracking growth of optically resolvable neurites. The Caenorhabditis elegans embryonic nervous system, comprising 222 neurons and 56 glia, is attractive for comprehensive studies of development; however, embryonic reporters are broadly expressed, making single-neurite tracking/manipulation challenging. We present a method, using an infrared laser, for reproducible heat-dependent gene expression in small sublineages (one to four cells) without radiation damage. We go beyond proof-of-principle, and use our system to label and track single neurons during early nervous-system assembly. We uncover a retrograde extension mechanism for axon growth, and reveal the aetiology of axon-guidance defects in sax-3/Robo and vab-1/EphR mutants. We also perform cell-specific rescues, determining DAF-6/patched-related site of action during sensory-organ development. Simultaneous ablation and labelling of cells using our system reveals roles for glia in dendrite extension. Our method can be applied to other optically/IR-transparent organisms, and opens the door to high-resolution systematic analyses of C. elegans morphogenesis.
Highlights
Visualizing neural-circuit assembly in vivo requires tracking growth of optically resolvable neurites
Our method uses an infrared laser to heat a single cell in the embryo and induces gene expression in that cell through heat-shockresponse regulatory elements (HREs)
We investigated the site of action of daf-6, a sensory-organ morphogenesis gene, revealing a requirement in glia
Summary
Visualizing neural-circuit assembly in vivo requires tracking growth of optically resolvable neurites. The Caenorhabditis elegans embryonic nervous system, comprising 222 neurons and 56 glia, is attractive for comprehensive studies of development; embryonic reporters are broadly expressed, making single-neurite tracking/manipulation challenging. While guidance molecules directing neurodevelopment have been extensively explored[1,2], real-time tracking of single neurites during nervous system assembly has been limited by the size and morphological complexity of nervous systems, as well as by technical challenges preventing high-resolution observation of neurite growth in living specimens. The embryonic Caenorhabditis elegans nervous system contains only 56 glia and 222 neurons, many of which form synaptic contacts in a brain neuropil called the nerve ring (NR) This small cell complement makes C. elegans attractive for comprehensive studies of nervous-system assembly. This leads to gene expression in small sublineages (one to four cells per embryo)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
