Meeting Abstract
The pteropod mollusk Clione limacina is a holoplanktonic gymnosome found in the northern Pacific and Atlantic Oceans as well as the Arctic Ocean. Its relatively complex behavioral hierarchy, which includes various swim states and feeding and reproductive behaviors, is supported by a simple, easily accessible central nervous system which makes it an ideal model organism for neurobiological studies. The buccal cones of Clione serve as hunting tentacles and contain three types of muscle tissue: smooth circular, smooth longitudinal, and striated longitudinal. The smooth circular muscle is responsible for buccal cone extrusion and the smooth and striated longitudinal muscles are believed to be involved in buccal cone retraction and prey manipulation, respectively. Several neurotransmitters and neuropeptides have been found to have modulatory effects on hunting behaviors including FMRFamide, serotonin, small cardioactive peptide b (SCPb), myomodulin, and buccalin. However, the distribution of these modulators relative to the muscle layers is unknown. This study uses immunohistochemistry at the light and transmission electron microscopy (TEM) levels to identify and describe contact locations within the buccal cones. FMRFamide, SCPb, myomodulin, and buccalin are found near the orally-concentrated, striated longitudinal muscles, while of serotonin can be seen at the bases of adhesive papillae. Synapses between SCPb reactive neurons and striated longitudinal muscles have been observed with TEM. These results provide further insight into the function of the buccal cone longitudinal muscles relative to the behavioral control of prey acquisition.
