title: Abundance of gap junctions at glutamatergic mixed synapses in adult Mosquitofish spinal cord neurons.
abstract: "Dye-coupling", whole-mount immunohistochemistry for gap junction channel protein connexin 35 (Cx35), and freeze-fracture replica immunogold labeling (FRIL) reveal an abundance of electrical synapses/gap junctions at glutamatergic mixed synapses in the 14th spinal segment that innervates the adult male gonopodium of Western Mosquitofish, Gambusia affinis (Mosquitofish). To study gap junctions' role in fast motor behavior, we used a minimally-invasive neural-tract-tracing technique to introduce gap junction-permeant or -impermeant dyes into deep muscles controlling the gonopodium of the adult male Mosquitofish, a teleost fish that rapidly transfers (complete in <20 mS) spermatozeugmata into the female reproductive tract. Dye-coupling in the 14th spinal segment controlling the gonopodium reveals coupling between motor neurons and a commissural primary ascending interneuron (CoPA IN) and shows that the 14th segment has an extensive and elaborate dendritic arbor and more gap junctions than do other segments. Whole-mount immunohistochemistry for Cx35 results confirm dye-coupling and show it occurs via gap junctions. Finally, FRIL shows that gap junctions are at mixed synapses and reveals that >50 of the 62 gap junctions at mixed synapses are in the 14th spinal segment. Our results support and extend studies showing gap junctions at mixed synapses in spinal cord segments involved in control of genital reflexes in rodents, and they suggest a link between mixed synapses and fast motor behavior. The findings provide a basis for studies of specific roles of spinal neurons in the generation/regulation of sex-specific behavior and for studies of gap junctions' role in regulating fast motor behavior. Finally, the CoPA IN provides a novel candidate neuron for future studies of gap junctions and neural control of fast motor behaviors.
authors.affiliation: Biological Imaging Group, University of Puerto Rico San Juan, PR, USA.
authors.forename: Jose L
authors.initials: JL
authors.lastname: Serrano-Velez
authors.affiliation: Biological Imaging Group, University of Puerto Rico San Juan, PR, USA.
authors.forename: Melanie
authors.initials: M
authors.lastname: Rodriguez-Alvarado
authors.affiliation: Biological Imaging Group, University of Puerto Rico San Juan, PR, USA.
authors.forename: Irma I
authors.initials: II
authors.lastname: Torres-Vazquez
authors.affiliation: Molecular and Computational Biology Section, University of Southern California Los Angeles, CA, USA.
authors.forename: Scott E
authors.initials: SE
authors.lastname: Fraser
authors.affiliation: Department of Biomedical Sciences, Colorado State University Fort Collins, CO, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Yasumura
authors.affiliation: Department of Biomedical Sciences, Colorado State University Fort Collins, CO, USA.
authors.forename: Kimberly G
authors.initials: KG
authors.lastname: Vanderpool
authors.affiliation: Department of Biomedical Sciences, Colorado State University Fort Collins, CO, USA ; Program in Molecular, Cellular and Integrative Neurosciences, Colorado State University Fort Collins, CO, USA.
authors.forename: John E
authors.initials: JE
authors.lastname: Rash
authors.affiliation: Biological Imaging Group, University of Puerto Rico San Juan, PR, USA ; Institute of Neurobiology, School of Medicine, University of Puerto Rico San Juan, PR, USA.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Rosa-Molinar
mesh_terms: D000818:Animals; D017630:Connexins / Q000378:metabolism; D005260:Female; D017629:Gap Junctions / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism*; D008297:Male; D009474:Neurons / Q000378:metabolism*; D011036:Poecilia / Q000378:metabolism; D013116:Spinal Cord / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism*
chemical_list: D017630:Connexins; C100585:connexin 35 protein, vertebrate; D018698:Glutamic Acid
keywords: connexin 35/36; connexins; dye-coupling; freeze-fracture replica immunogold labeling; gap junctions; mixed synapses; neurons; spinal cord