Worm Breeder's Gazette 11(2): 95
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
We have earlier reported that a monoclonal antibody 6-11B-1 made against sea urchin axonemes and specific for the acetylated alpha tubulin (kindly provided by G. Piperno) stains the set of six mechanosensory neurons ALML, ALMR, AVM, PLML, PLMR and PVM (Siddiqui, S., Aamodt, E., Rastinejad, F. and Culotti, J; J. Neurosci. 9, 2963, 1989). PVM is lightly stained in the wild type, but stains brightly as other touch neurons in an anterior position in mab-5 animals. In addition to the set of six touch neurons, a unique neuron in the right lumbar ganglion, PVR is brightly stained, immunocytochemically, with 6- 11B-1 antibodies. PVR is a bipolar neuron (White et al. 1986, D. Hall and R. Russell, 1989), projects a posteriorly directed process well into the end of the tail spike. The anteriorly directed process of PVR, leaves the cell body and grows along the ventral cord, reaching via the lumbar commissure. Of the touch neurons, it has synaptic interactions with ALM, AVM, PVM, and PVM neurons in the form of gap junctions. The main synaptic interaction in the nerve ring is directed to AVB, RIP, and AVJ, and a gap junction to ALM. In the ventral cord the synaptic input is from AVM, DVA, and PVM, and there are gap junctions to DVA and PLMR. These observations imply a role for PVR in the neural circuitry mediating touch sensitivity in C. elegans.We have begun experiments by laser ablating the precursor cell Caa in the developing wild type embryos, which gives rise to the PVR in the right lumbar ganglion. This is the only neuron, derived from the C-lineage, which is present in the lumbar ganglia. So far, we have ablated Caa cell in eight embryos. Four of these embryos did not hatch. Of the four survivors, two were clearly touch sensitive in the tail, as tested by a light touch with a hair. However, two remaining hatchees, were less sensitive to the light touch. The touch sensitivity of all four hatchees , when tested in the head region, was found to be normal. These experiments were conducted in collaboration with Johji Miwa and Kenichi Higashi of NEC, at their Tsukuba lab. We need to do many more ablations to determine the role of PVR in the touch circuitry We also plan to stain the ablated animals with the 6- 11B-1 antibodies to ascertain if PVR is present or not in the manipulated animals. [See Figure 1]