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?
Zebrafish: outstanding model studying photoreceptor degenerations
larvae
adult
•
•
Contains red, green, blue and UV cone cells
Contains rods
Advantages:
•Ex utero rapid development
•Optical transparency
•Permeability to drugs
•Ease of making transgenetic animal
•The acute visual abilities of 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/
metabotropic
glutamate receptor
ionotropic
glutamate receptor
Na+
K+
http://what-when-how.com/neuroscience/visual-system-sensory-system-part-2/
A
B
M
ON
ON
OFF
OFF
ribbon
http://webvision.med.utah.edu/book/part-ii-anatomy-and-physiology-of-the-retina/oute-plexiform/
Confocal Microscopy
Result 1: development of ON bipolar cell contacts with rod and cone photoreceptors
nyx:mYFPq16
cones
rods
OPL
ON
bipolar cell
Cone pedicle
ON
bipolar cell
Rod spherule
dendrites
cones
rods
Result 2: cone degeneration in pde6cw59 mutant larvae leads to ON bipolar cell remodeling
pde6cw59 transgenic
cone degeneration
cones
ON bipolar cell
ON bipolar cell
rods
Xops:mCFPq13 transgenic
ON bipolar cell
rod degeneration
ON bipolar cell
Result 2: cone degeneration in pde6cw59 mutant larvae leads to ON bipolar cell remodeling
pde6cw59 transgenic
D6
ON bipolar axon terminals
cone degeneration
6 DPF
D8
Xops:mCFPq13 transgenic
8 DPF
rod degeneration
Result 3: postsynaptic glutamate receptor expression is altered in pde6cw59 larvae
OFF bipolar cell
ON bipolar cell
horizontal cell
ON bipolar cell
D6
pde6cw59 transgenic
Xops:mCFPq13 transgenic
6 DPF
cone degeneration
D8
rod degeneration
8 DPF
Result 4: synaptic structure is maintained in Xops:mCFPq13 and pde6cw59 adults
cones
ON bipolar cell
ON bipolar cell
cones
ON bipolar cell
ON bipolar cell
cones
ON bipolar cell
ON bipolar cell
Result 4: synaptic structure is maintained in Xops:mCFPq13 and pde6cw59 adults
photoreceptor terminals
photoreceptor terminals
photoreceptor terminals
horizontal cell
horizontal cell
Cone pedicle
rod spherule
horizontal cell
Result 5: visual responses are preserved in pde6cw59 mutant adults
diffuse white light
Result 5: visual responses are preserved in pde6cw59 mutant adults
• Optokinetic response (OKR):
http://www.youtube.com/watch?v=mfstlvsW1IY
• WT and pde6cw59 adults display a robust OKR.
Result 6: increased rod number protects the larval retina from cone degenerationinduced remodeling
nuclear
rod
ON bipolar cell
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 degenerationinduced 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?