Table 2. Provisional nominations of putative amphid neuronal homologs between C. elegans and P. pacificus.
Morphological data based on TEM series of specimens 107 and 148. Features supporting cellular homology include axon projections, lipophilic dye uptake, cell body positions, and chemical synapses to the four first layer amphid interneurons (AIA, AIB, AIY, AIZ) or the AUA. DiI filling neurons in C. elegans are ASI, ASJ, ASK, ADL, ASH, AWB (weak), *ADF (shows only weak FITC uptake, not DiI). DiO filling neurons in C. elegans are ASI, ASJ, ASK, ADL, ASH, AWB. PCMC: periciliary membrane compartment. Structures of C. elegans amphid neurons are available at http://www.wormatlas.org/images/NeuronImageList.jpg.
| P. pacificus neuron | Axon termination site in nerve ring | Dye filling | Feature(s) supporting homology | Likely C. elegans homolog | Main difference compared to C. elegans |
|---|---|---|---|---|---|
| AM1 | dorsal midline | DiI only | DiI uptake, cell position, cell body morphology | ASH | lack DiO uptake |
| AM2 | dorsal midline | DiI + DiO | DiI + DiO uptake; branched axon not through commissure; AIA/AIB | ADL | single ciliated vs. dual ciliated |
| AM3 | dorsal midline | none | none | AWA | dual ciliated vs. wing; Ppa-odr-3 expression |
| AM4 | dorsal midline | DiI only | DiI uptake; AIA/AIB | ASK | lack of DiO uptake; Ppa-odr-3 expression; |
| AM5 | dorsal midline | none | Ppa-che-1 expression | ASE | axons cross the midline in C. el. |
| AM6 | lateral midline | none | short axons;cell position | ASG | Ppa-che-1 expression |
| AM7 | cross dorsal midline | none | axons overlap dorsally; dorsal sheath entry;cell position; AIA/AIB/AIY/AIZ | AWC | single ciliated vs. wing; Ppa-odr-7 expression |
| AM8 | dorsal midline | DiI + DiO | DiI and DiO uptake; ventral sheath entry;cell position | ASJ | none |
| AM9 | dorsal midline | DiI only | dual ciliated; DiI uptake*; prominent PCMC; connect to AUA | ADF | Ppa-odr-7 expression |
| AM10 | dorsal midline | none | AIA/AIB/AIY/AIZ | ASI | lack DiI and DiO uptake |
| AM11 | dorsal midline | DiI only | weak DiI uptake; cell position; AIA/AIB/AIY/AIZ | AWB | single ciliated vs. wing; lack DiO uptake |
| AM12 | dorsal midline | none | finger dendrite morphology; cell position; first to enter the AMsh | AFD | more posterior position in AMsh due to lack of winged neurons |
| AMU1 | dorsal midline | none | short ‘dendritic’ process; cell position; exclusive output of ADF | AUA | none |