title: Type 4 OFF cone bipolar cells of the mouse retina express calsenilin and contact cones as well as rods.
abstract: Immunocytochemical discrimination of distinct bipolar cell types in the mouse retina is a prerequisite for analyzing retinal circuitry in wild-type and transgenic mice. Here we demonstrate that among the more than 10 anatomically defined mouse bipolar cell types, type 4 bipolar cells are specifically recognized by anti-calsenilin antibodies. Axon terminals in the inner plexiform layer are not readily identifiable because calsenilin is also expressed in a subset of amacrine and ganglion cells. In contrast, in the outer plexiform layer calsenilin immunoreactivity allows the analysis of photoreceptor to type 4 bipolar cell contacts. A dense plexus of calsenilin-positive dendrites makes several basal contacts at cone pedicles. An individual calsenilin-positive bipolar cell contacts five to seven cones. In addition, some calsenilin-positive dendrites contact rod photoreceptors. On average we counted 10 rod spherule contacts per type 4 bipolar cell, and approximately 10% of rods contacted type 4 bipolar cells. We suggest that type 4 bipolar cells, together with the recently described type 3a and b cells, provide an alternative and direct route from rods to OFF cone bipolar cells. In the Bassoon DeltaEx4/5 mouse, a mouse mutant that shows extensive remodeling of the rod system including sprouting of horizontal and rod bipolar cells into the outer nuclear layer due to impaired synaptic transmission, we found that in addition mixed-input (type 3 and 4) OFF bipolar cells sprout to ectopic sites. In contrast, true cone-selective type 1 and 2 OFF cone bipolar cells did not show sprouting in the Bassoon mouse mutant.
authors: Department of Neuroanatomy, Max Planck Institute for Brain Research, 60528 Frankfurt/Main, Germany.
authors: Silke
authors: S
authors: Haverkamp
authors: Dana
authors: D
authors: Specht
authors: Sriparna
authors: S
authors: Majumdar
authors: Nikhat F
authors: NF
authors: Zaidi
authors: Johann Helmut
authors: JH
authors: Brandstätter
authors: Wilma
authors: W
authors: Wasco
authors: Heinz
authors: H
authors: Wässle
authors: Susanne
authors: S
authors: Tom Dieck
mesh_terms: D000818:Animals; D000906:Antibodies; D003712:Dendrites / Q000378:metabolism / Q000648:ultrastructure; D051605:Kv Channel-Interacting Proteins / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL / Q000502:physiology*; D008817:Mice, Mutant Strains; D016253:Microscopy, Immunoelectron; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009434:Neural Pathways; D012160:Retina / Q000166:cytology* / Q000502:physiology* / Q000648:ultrastructure; D051245:Retinal Bipolar Cells / Q000166:cytology / Q000502:physiology / Q000648:ultrastructure; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology / Q000502:physiology / Q000648:ultrastructure; D017948:Retinal Rod Photoreceptor Cells / Q000166:cytology / Q000502:physiology / Q000648:ultrastructure; D013569:Synapses / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D000906:Antibodies; C498441:Bsn protein, mouse; D051605:Kv Channel-Interacting Proteins; D009419:Nerve Tissue Proteins