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Updated: Aug 10, 2026
In vivo Laser Axotomy in C. elegans
Published on: May 19, 2011
Pharyngeal pumping continues after laser killing of the pharyngeal nervous system of C. elegans
1Department of Biology, Massachusetts Institute of Technology, Cambridge. 02139.
Abstract:
Using a laser microbeam to kill specific subsets of the pharyngeal nervous system of C. elegans, we found that feeding was accomplished by two separately controlled muscle motions, isthmus peristalsis and pumping. The single neuron M4 was necessary and sufficient for isthmus peristalsis. The MC neurons were necessary for normal stimulation of pumping in response to food, but pumping continued and was functional in MC- worms. The remaining 12 neuron types were also unnecessary for functional pumping. No operation we did, including destruction of the entire pharyngeal nervous system, abolished pumping altogether. When we killed all pharyngeal neurons except M4, the worms were viable and fertile, although retarded and starved. Since feeding is one of the few known essential actions controlled by the nervous system, we suggest that most of the C. elegans nervous system is dispensable in hermaphrodites under laboratory conditions. This may explain the ease with which nervous system mutants are isolated and handled in C. elegans.
Insights
Most of the C. elegans nervous system is dispensable for feeding, a vital function. Even with most neurons removed, worms could still pump food, suggesting nervous system redundancy.
Area of Science:
- Neuroscience
- Developmental Biology
- Genetics
Background:
- Feeding is a fundamental behavior essential for survival.
- The nervous system controls complex behaviors, but the extent of its necessity is often unclear.
- Caenorhabditis elegans (C. elegans) is a model organism for studying neurobiology due to its simple, well-characterized nervous system.
Purpose of the Study:
- To investigate the necessity of specific neurons in the C. elegans pharyngeal nervous system for feeding.
- To determine the minimal neuronal requirements for essential functions like feeding.
- To understand the dispensability of the nervous system under laboratory conditions.
Main Methods:
- Laser ablation was used to selectively destroy subsets of neurons in the C. elegans pharyngeal nervous system.
- Feeding behavior, specifically isthmus peristalsis and pumping, was monitored.
- The viability, fertility, and overall health of manipulated worms were assessed.
Main Results:
- Feeding is mediated by two distinct muscle actions: isthmus peristalsis and pumping.
- The M4 neuron is both necessary and sufficient for isthmus peristalsis.
- MC neurons are required for normal pumping stimulation, but pumping remains functional even when MC neurons are ablated.
- Destruction of all pharyngeal neurons did not abolish pumping; worms with only the M4 neuron survived and reproduced, albeit with deficits.
Conclusions:
- A significant portion of the C. elegans pharyngeal nervous system is dispensable for feeding in hermaphrodites under laboratory conditions.
- The redundancy observed in the nervous system may facilitate the isolation and study of neuronal mutants.
- This finding has implications for understanding nervous system evolution and function in model organisms.
