Nitric Oxide Producing Cells in the Central Nervous System and Peripheral Tissues of Mercenaria Mercenaria (Bivalvia)
Untch, Brian R.
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Nitric Oxide (NO) has been observed as a signaling molecule within several invertebrate species. However, NO producing cells have yet to be detected in bivalves. NADPH-diaphorase histochemistry and RT-PCR were employed to detect nitric oxide synthase (NOS) in the bivalve mollusk, Mercenaria mercenaria. NADPH-diaphorase histochemistry was used to analyze the distribution of putative NOS-containing cells. Serial cryostat sections and whole mount preparations were made from the cerebral ganglion, visceral ganglion, pedal ganglion, gills, esophagus, intestine, palps, foot, and gonad. In the CNS, the most prominent neuronal staining was located in the visceral ganglion followed by the pedal and cerebral ganglia. In the periphery, selective labeling occurred in subephithelial non-neuronal cells located in the gills, esophagus, and in the ciliated epithelium of the gut. The gonad areas and posterior pedal muscles were negative for NADPH-diaphorase. RT -PCR successfully isolated a 522 base pair fragment of the neuronal NOS isoform from CNS tissues. The amino acid sequence showed highest homologies to the three known gastropod neuronal NOS's, but was similar to several other invertebrate and vertebrate sequences. These data suggest that nitric oxide is used as a signaling molecule within the CNS and peripheral tissue of M mercenaria and possibly in other bivalve species.With honors.