title: A novel transgenic zebrafish model for blood-brain and blood-retinal barrier development.
abstract: BACKGROUND
  Development and maintenance of the blood-brain and blood-retinal barrier is critical for the homeostasis of brain and retinal tissue. Despite decades of research our knowledge of the formation and maintenance of the blood-brain (BBB) and blood-retinal (BRB) barrier is very limited. We have established an in vivo model to study the development and maintenance of these barriers by generating a transgenic zebrafish line that expresses a vitamin D-binding protein fused with enhanced green fluorescent protein (DBP-EGFP) in blood plasma, as an endogenous tracer.
  
  
  RESULTS
  The temporal establishment of the BBB and BRB was examined using this transgenic line and the results were compared with that obtained by injection of fluorescent dyes into the sinus venosus of embryos at various stages of development. We also examined the expression of claudin-5, a component of tight junctions during the first 4 days of development. We observed that the BBB of zebrafish starts to develop by 3 dpf, with expression of claudin-5 in the central arteries preceding it at 2 dpf. The hyaloid vasculature in the zebrafish retina develops a barrier function at 3 dpf, which endows the zebrafish with unique advantages for studying the BRB.
  
  
  CONCLUSIONS
  Zebrafish embryos develop BBB and BRB function simultaneously by 3 dpf, which is regulated by tight junction proteins. The Tg(l-fabp:DBP-EGFP) zebrafish will have great advantages in studying development and maintenance of the blood-neural barrier, which is a new application for the widely used vertebrate model.
authors.affiliation: Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA. xiej@ccf.org
authors.forename: Jing
authors.initials: J
authors.lastname: Xie
authors.forename: Eric
authors.initials: E
authors.lastname: Farage
authors.forename: Masahiko
authors.initials: M
authors.lastname: Sugimoto
authors.forename: Bela
authors.initials: B
authors.lastname: Anand-Apte
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001812:Blood-Brain Barrier / Q000196:embryology*; D001813:Blood-Retinal Barrier / Q000196:embryology*; D062507:Claudin-5; D057167:Claudins / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D015027:Zebrafish / Q000196:embryology*; D029961:Zebrafish Proteins / Q000378:metabolism
chemical_list: D062507:Claudin-5; D057167:Claudins; D008565:Membrane Proteins; D029961:Zebrafish Proteins; C547662:cldn5a protein, zebrafish; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins