Zebrafish Tg(7.2mab21l2:EGFP)ucd2 transgenics reveal a unique population of retinal amacrine cells.
OBJECTIVE
Amacrine cells constitute a diverse, yet poorly characterized, cell population in the inner retina. Here, the authors sought to characterize the morphology, molecular physiology, and electrophysiology of a subpopulation of EGFP-expressing retinal amacrine cells identified in a novel zebrafish transgenic line.


METHODS
After 7.2 kb of the zebrafish mab21l2 promoter was cloned upstream of EGFP, it was used to create the Tg(7.2mab21l2:EGFP)ucd2 transgenic line. Transgenic EGFP expression was analyzed by fluorescence microscopy in whole mount embryos, followed by detailed analysis of EGFP-expressing amacrine cells using fluorescence microscopy, immunohistochemistry, and electrophysiology.


RESULTS
A 7.2-kb fragment of the mab21l2 promoter region is sufficient to drive transgene expression in the developing lens and tectum. Intriguingly, EGFP was also observed in differentiated amacrine cells. EGFP-labeled amacrine cells in Tg(7.2mab21l2:EGFP)ucd2 constitute a novel GABA- and glycine-negative amacrine subpopulation. Morphologically, EGFP-expressing cells stratify in sublamina 1 to 2 (type 1 OFF) or sublamina 3 to 4 (type 1 ON) or branch diffusely (type 2). Electrophysiologically, these cells segregate into amacrine cells with somas in the vitreal part of the INL and linear responses to current injection or, alternatively, amacrine cells with somas proximal to the IPL and active oscillatory voltage signals. CONCLUSIONS; The novel transgenic line Tg(7.2mab21l2:EGFP)ucd2 uncovers a unique subpopulation of retinal amacrine cells.
UCD School of Biomolecular and Biomedical Sciences, UCD Conway Institute, University College Dublin, Dublin, Ireland. marialcederlund@gmail.com
Maria L
ML
Cederlund
Maria E
ME
Morrissey
Tom
T
Baden
Dimitri
D
Scholz
Victor
V
Vendrell
Leon
L
Lagnado
Victoria P
VP
Connaughton
Breandán N
BN
Kennedy
D025042:Amacrine Cells / Q000166:cytology* / Q000378:metabolism; D000818:Animals; D030801:Animals, Genetically Modified; D064032:Calbindin 2; D004594:Electrophysiology; D004625:Embryo, Nonmammalian / Q000166:cytology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D005998:Glycine / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics*; D007150:Immunohistochemistry; D008856:Microscopy, Fluorescence; D010320:Parvalbumins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012160:Retina / Q000196:embryology* / Q000378:metabolism; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000235:genetics*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D064032:Calbindin 2; D018398:Homeodomain Proteins; D010320:Parvalbumins; D064030:S100 Calcium Binding Protein G; D029961:Zebrafish Proteins; C485184:enhanced green fluorescent protein; C499233:mab21l2 protein, zebrafish; D049452:Green Fluorescent Proteins; D005680:gamma-Aminobutyric Acid; D005998:Glycine