Spectral Sensitivity of Sensory Motor Integration of Gill Lateral Cell Cilia in the Bivalve Mollusc Crassostrea virginica

Gill lateral cells of Crassostrea virginica are innervated by serotonin and dopamine nerves from their ganglia. Most bivalves have lateral cell cilia that respond to serotonin, which is cilio‐excitatory, and dopamine, which is cilio‐inhibitory. The motor aspects of gill lateral cell innervation have been well studied, but not the sensory side. Recently we found various sensory cues, including light, initiated a sensory‐motor integration response between mantle rim sensory tentacles and gill lateral cell cilia, via the visceral and cerebral ganglia. We also found that in animal preparations in which their shells removed, the cerebral ocelli (eyespots) responded to light causing lateral cell cilia to decrease beating rates. We hypothesize that light can penetrate oyster shell and stimulate cerebral ocelli to initiate a motor response of gill lateral cell cilia. In addition we hypothesize that if light does penetrate the shell, certain wavelengths will be more effective in stimulating sensory cells in ocelli and mantle rim tentacles. To test this we first measured light transmittance through shells using a Beckman DU800 spectrophotometer and found red light (650+ nm) produced the greatest degree of transmittance through the shell. Using animal preparations with intact gill to cerebral/visceral ganglia innervation we found that white light shown though the shell stimulated ocelli to initiate a motor response to slow down gill lateral cell cilia beating rates. Cilia beating was measured by stroboscopic microscopy and expressed as beats/sec ± sem. Then using different wavelengths of light (blue ‐ 405 nm, green ‐525 nm, amber ‐ 591 nm, red – 680 nm) we stimulated mantle rim sensory tentacles and cerebral ocelli with the shell in place. Under these conditions we found that only red light resulted in a sensory‐motor response that slowed lateral cell cilia beating rates. Cilia beating rates slowed from a basal rate of about 15 beats/sec to zero over a 20 minute period. These results were statistically significant and the other tested wavelengths had no significant effect on cilia beating rates. This study further demonstrates the integration of photosensory signals in the control of gill lateral cell cilia in the bivalve C. virginica , and adds new knowledge that demonstrates a spectral sensitivity of sensory cells in the cerebral ocelli and mantle rim tentacle involved with this sensory‐motor integration response. Support or Funding Information Supported by grant 690340047 of PSC‐CUNY, grant 2R25GM06003 of the Bridge Program of NIGMS and a Carnegie Foundation award. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .