title: Electrical synaptic transmission in developing zebrafish: properties and molecular composition of gap junctions at a central auditory synapse.
abstract: In contrast to the knowledge of chemical synapses, little is known regarding the properties of gap junction-mediated electrical synapses in developing zebrafish, which provide a valuable model to study neural function at the systems level. Identifiable "mixed" (electrical and chemical) auditory synaptic contacts known as "club endings" on Mauthner cells (2 large reticulospinal neurons involved in tail-flip escape responses) allow exploration of electrical transmission in fish. Here, we show that paralleling the development of auditory responses, electrical synapses at these contacts become anatomically identifiable at day 3 postfertilization, reaching a number of ∼6 between days 4 and 9. Furthermore, each terminal contains ∼18 gap junctions, representing between 2,000 and 3,000 connexon channels formed by the teleost homologs of mammalian connexin 36. Electrophysiological recordings revealed that gap junctions at each of these contacts are functional and that synaptic transmission has properties that are comparable with those of adult fish. Thus a surprisingly small number of mixed synapses are responsible for the acquisition of auditory responses by the Mauthner cells, and these are likely sufficient to support escape behaviors at early developmental stages.
authors: Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York;
authors: Cong
authors: C
authors: Yao
authors: Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado; and.
authors: Kimberly G
authors: KG
authors: Vanderpool
authors: Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York;
authors: Matthew
authors: M
authors: Delfiner
authors: Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York;
authors: Vanessa
authors: V
authors: Eddy
authors: Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York;
authors: Alexander G
authors: AG
authors: Lucaci
authors: Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York;
authors: Carolina
authors: C
authors: Soto-Riveros
authors: Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado; and.
authors: Thomas
authors: T
authors: Yasumura
authors: Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado; and Program in Molecular, Cellular and Integrative Neurosciences, Colorado State University, Fort Collins, Colorado.
authors: John E
authors: JE
authors: Rash
authors: Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York; alberto.pereda@einstein.yu.edu.
authors: Alberto E
authors: AE
authors: Pereda
mesh_terms: D000818:Animals; D001306:Auditory Pathways / Q000254:growth & development / Q000502:physiology; D017630:Connexins / Q000235:genetics / Q000378:metabolism; D054351:Electrical Synapses / Q000502:physiology*; D017629:Gap Junctions / Q000378:metabolism / Q000502:physiology*; D007814:Larva / Q000254:growth & development / Q000502:physiology; D012249:Rhombencephalon / Q000254:growth & development / Q000502:physiology*; D009435:Synaptic Transmission; D015027:Zebrafish; D000097004:Gap Junction delta-2 Protein
chemical_list: D017630:Connexins; D000097004:Gap Junction delta-2 Protein
keywords: Mauthner cell; auditory development; connexin 35; connexin 36; escape response