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