Authors/Affiliations: Lynnette A. Martínez-Rivera¹, Ivana del Valle¹, Dina P. Bracho-Rincón¹, and Mark W. Miller, PhD¹

¹Institute of Neurobiology, Department of Anatomy & Neurobiology, University of Puerto Rico, Medical Sciences Campus, PO Box 365067, San Juan, Puerto Rico 00901

Introduction: About 200 million people risk contracting the parasitic disease schistosomiasis. Schistosoma mansoni, a digenetic trematode, employs the freshwater snail Biomphalaria glabrata as its primary intermediate host. Infection of B. glabrata by S. mansoni causes profound behavioral changes in the snail host. However, neural mechanisms involved in these changes remain unknown.

Methods: This study used a neural transcriptomics approach to identify messages that could encode neuropeptides involved in Biomphalaria sensory-motor circuits. One transcript encoded a precursor polypeptide that could give rise to the neuropeptide HKYRVGYLF-NH₂, termed Biom-sensorin.  Affinity-purified polyclonal antibodies (rabbit) were generated against C-HKYRVGYLF-NH2. Double-labeling experiments combined whole-mount immunohistochemistry with the Hybridization Chain Reaction (HCR) in-situ hybridization technique (Molecular Instruments, LA CA).

Results: Sensorin-like immunoreactivity was observed throughout the central nervous system (CNS) and specific peripheral tissues. Both methods labeled groups of sensorin-like immunoreactive neurons that project to peripheral nerves. These included two large (20-30 μm) cells in the anterior lobe of the cerebral ganglion, 5-6 medium-sized (15-20 μm) cells in the anteromedial left parietal ganglion, and 7-8 smaller (10-15 μm) cells in the left parietal ganglion. No double-labeled cells were detected in the anterior lobe of the cerebral ganglion. Within the left parietal and visceral ganglia, clusters of large cells gave rise to axons projecting to the anal and intestinal nerves. Sensorin-like immunoreactive fibers were also present in the lip, mantle, and foot.

Conclusion: These results suggest that Biom-sensorin could participate in the detection of aversive stimuli, as shown in other gastropods.

Acknowledgements: Supported by the U.S. National Institute of Health and the U.S. National Science Foundation. Reagents were provided by the Schistosomiasis Resource Center of the Biomedical Research Institute.