PVD and FLP sensory neurons envelope the body of the C. elegans adult with a highly branched network of thin sensory processes. Both PVD and FLP neurons are mechanosensors. PVD is known to mediate the response to high threshold mechanical stimuli. Thus PVD and FLP neurons are similar in both morphology and function to mammalian nociceptors. To better understand the function of these neurons we generated strains lacking them. Behavioral analysis shows that PVD and FLP regulate movement under normal growth conditions, as animals lacking these neurons demonstrate higher dwelling behavior. In addition, PVD-whose thin branches project across the body-wall muscles-may have a role in proprioception, as ablation of PVD leads to defective posture. Moreover, movement-dependent calcium transients are seen in PVD, a response that requires MEC-10, a subunit of the mechanosensory DEG/ENaC channel that is also required for maintaining wild-type posture. Hence, PVD senses both noxious and innocuous signals to regulate C. elegans behavior, and thus combines the functions of multiple mammalian somatosensory neurons. Finally, strong mechanical stimulation leads to inhibition of egg-laying, and this response also depends on PVD and FLP neurons. Based on all these results we suggest that noxious signals perceived by PVD and FLP promote an escape behavior consisting of increased speed, reduced pauses and reversals, and inhibition of egg-laying.
Bibliographical noteFunding Information:
This research was supported by U. S.–Israel Binational Science Foundation Grant 2005036 (MT and DMM), by NIH R21 NS6882 and R01 NS26115 (DMM), and by NIH RR12596 (to DHH). We thank John White and Jonathan Hodgkin for the donation of the MRC/LMB electron microscopy archives to the Hall lab, the C. elegans Genetic Center for strains, Hezi Gottlieb for help with image acquisition, Gady Brinker for help with image analysis software, Chris Crocker for the artwork in Fig. 2 , Dattananda Chelur for the mec-10 promoter, Sylvia Lee for the mec-7:RFP transgenic line, and Jessica Von Stetina for generating myo-3:dsRed2 animals. Appendix A
- C. elegans
- Somatosensory system