Presented by Juan Mo. Study Questions Why zebrafish transgenetic lines are very important for...
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Transcript of Presented by Juan Mo. Study Questions Why zebrafish transgenetic lines are very important for...
Presented by Juan Mo
Study Questions
• Why zebrafish transgenetic lines are very important for studying photoreceptor degeneration?
• The synapses in inner plexiform layer and in outer plexiform layer?
• ON bipolar cell & OFF bipolar cell?• What are the larval and adult phenotypes of pde6cw59 and Xops:mCFPq13 lines?
• Light and dark preference test?• How does morpholino injection knock down gene
expression?
• Contains red, green, blue and UV cone cells• Contains rods
Zebrafish: outstanding model studying photoreceptor degenerations
Advantages:•Ex utero rapid development•Optical transparency•Permeability to drugs•Ease of making transgenetic animal•The acute visual abilities of larvae
adult larvae
pde6cw59 transgenic line cone degeneration death of rod (larvae) rod persistence (juvenile and adult) Xops:mCFPq13 transgenic line rod degeneration loss of cone (mammanlian) cone unaffected (zebrafish)
Hypothesis
• Rod photoreceptors protects from cone degeneration-induced retinal remodeling and restore visual responses in zebrafish
http://what-when-how.com/neuroscience/visual-system-sensory-system-part-2/
K+
metabotropic glutamate receptor
ionotropicglutamate receptor
Na+
http://what-when-how.com/neuroscience/visual-system-sensory-system-part-2/
ON ON
OFF OFF
http://webvision.med.utah.edu/book/part-ii-anatomy-and-physiology-of-the-retina/oute-plexiform/
ribbon
M
A B
Confocal Microscopy
Result 1: development of ON bipolar cell contacts with rod and cone photoreceptors
cones rods
ON bipolar cell
OPL
Cone pedicle Rod spherule
dendrites
ON bipolar cell
conesrods
nyx:mYFPq16
Result 2: cone degeneration in pde6cw59 mutant larvae leads to ON bipolar cell remodeling
rods
cones
ON bipolar cell
ON bipolar cell
ON bipolar cell
ON bipolar cell
pde6cw59 transgenic
cone degeneration
Xops:mCFPq13 transgenic
rod degeneration
D6
D8
Result 2: cone degeneration in pde6cw59 mutant larvae leads to ON bipolar cell remodeling
pde6cw59 transgenic
cone degeneration
Xops:mCFPq13 transgenic
rod degeneration8 DPF
ON bipolar axon terminals
6 DPF
Result 3: postsynaptic glutamate receptor expression is altered in pde6cw59 larvae
OFF bipolar cell
ON bipolar cell
ON bipolar cell
horizontal cell
D6
D8
pde6cw59 transgenic
cone degeneration
Xops:mCFPq13 transgenic
rod degeneration
8 DPF
6 DPF
Result 4: synaptic structure is maintained in Xops:mCFPq13 and pde6cw59 adults
cones
ON bipolar cell
ON bipolar cell ON bipolar cell ON bipolar cell
cones cones
ON bipolar cell ON bipolar cell
Result 4: synaptic structure is maintained in Xops:mCFPq13 and pde6cw59 adults
photoreceptor terminals
horizontal cell
rod spheruleCone pedicle
photoreceptor terminals photoreceptor terminals
horizontal cellhorizontal cell
Result 5: visual responses are preserved in pde6cw59 mutant adults
diffuse white light
• Optokinetic response (OKR):
http://www.youtube.com/watch?v=mfstlvsW1IY
• WT and pde6cw59 adults display a robust OKR.
Result 5: visual responses are preserved in pde6cw59 mutant adults
Result 6: increased rod number protects the larval retina from cone degeneration-induced remodeling
rod
ON bipolar cell
nuclear
Morpholino: knock down gene translation
Conclusion
• Cone degeneration leads to ON bipolar cell remodeling in larvae.• Although the neural connectivity remains intact, the loss of the majority
of the presynaptic input leads to significant remodeling observed in cone degeneration adult.
• Visual responses are preserved in cone degeneration adult.• Increased rod number protects the larval retina from cone
degeneration-induced remodeling.
?Rod photoreceptors protects from cone degeneration-induced retinal remodeling and restore visual responses in zebrafish
Review Questions
• Why zebrafish transgenetic lines are very important for studying photoreceptor degeneration?
• The synapses in inner plexiform layer and in outer plexiform layer?
• ON bipolar cell & OFF bipolar cell?• What are the larval and adult phenotypes of pde6cw59 and Xops:mCFPq13 lines?
• Light and dark preference test?• How does morpholino injection knock down gene
expression?