200400
600800
10001200
14001600
0
5
10
15
20
25
Length (mm)
D (m
m2/
s)
Gregor 2007
• Use GFP-Bcd to further 2005 work
• Use time-lapse two-photon microscopy– Fast and sensitive
• See Bcd on nuclei and anterior to posterior gradient
Gregor 2007
• Fluorescence increases with time
Quick Summary
• Bcd pattern seems to be established early and then stay regardless of – Nuclear proliferation– Nuclei size changes– Appearance of cell membranes
• Rises and falls with mitosis– Stays constant within for different divisions
• D is really small • Propose a new model that specifies nuclear
degradation
Castle
• More recently have shown that characteristic lengths of source ~ gradient length
• Suggest there might be localized production necessary to give rise to patterns
• Big focus on methods take issue with the photobleaching in Gregor 2007
• Model their work and find their estimate of D is off and diffusion model still holds
Is GFP-Bcd functional/normal?
• Yes.• GFP-Bcd can rescue a
knockout• Pattern the same as wt • Stain for endogenous
and GFP Bcd show colocalization
Getting strange
• Bcd associated with nuclei seems to spread out during mitosis?
• Pretty constant
• Is it just binding/unbinding from nuclei?• Use photobleaching to show recovery– Implies transport across nuclear membrane– And also degredation
• Make a new model