In Situ Hybridization of Zebrafish Embryos

In Situ Hybridization of ZF embryos 2 of 6

IN SITU HYBRIDIZATION OF ZEBRAFISH EMBRYOS:

Use RNase free 1.5 mL eppendorf tubes for incubation. Use The Pipette Pump F37898 from Bel-Art Products Pequannock, NJ and a glass Pasteur pipette unmodified for taking off liquid or a glass pipette with the end broken off and smoothed by flame to allow a wider opening to take up embryos.

Wash with dH2O before using. Add liquid to side of tube, especially after dechorionation, so embryos do not break. Also do not expose embryos to air or they will degrade. Good stages to look at first are 5S, 18S, 24S, 30S,48 hr. Take 5 embryos per stage.

Day One (estimated time ~ 5 hrs)

1.  Rehydrate embryos with 1 mL as follows (embryos are fixed O/N at 4˚C in 4% PFA in PBS, then was washed with PBST 2X5’, equilibrated with 4-5 changes of methanol and stored in 100% methanol at 20˚C in glass specimen vials or eppendorf tubes. Embryos can be stored years like this):

a.  75% methanol + 25% PBST 5 min

b.  50% methanol + 50% PBST 5 min

c.  25% methanol + 75% PBST 5 min

2.  Wash embryos with 100% PBST 5 X 5 min. (At any point you can leave embryos in PBST for longer).

3.  Dechorionate embryos. Use Stemi 2000-CS Zeiss dissecting microscope with FOSTEC Schott-Fostec, LLC EKE Ace I power supply for light. Use small forceps with sharp points at end. Put embryos in 100% PBST in petri dish and remove chorion by either of 2 methods:

a.  Put forceps on both sides and pull in opposite directions

b.  “Guide” embryo out of chorion. Be careful, they are fragile!

4.  Treat embryos with proteinase K (1 mL/tube) to put holes in membrane so RNA can get in:
Stock [c] = 1 mg/mL; stored at - 20˚C
Working [c] = 10 ug/mL
therefore, 10 mL for 1 mL (1:100) in RNase free H2O
time = 5-10 min for pre 1S (before 10.5 hr)
50-15 min for pre 16 hr
15-25 min for post 16 hr
15 min for post 16 hr
20 min for 52 hr
25 min for > 25 hr

5.  Quick rinse with PBST 2X (1mL/tube)

6.  Refix embryos in 4% PFA in PBS (stored at 4˚C) 20 min at RT.

7.  Rinse in PBST 5 X 5 min.

8.  Prehybridize for 2 hr at 65˚C in 300 uL hyb buffer.
30 min before end of prehyb, prepare probe preheated in 65˚C for 30 min.
stock for antisense probes is already at 1:10 dilution for hybridization, need 1:200 dilution
Therefore, take 190 uL hyb buffer + 10 uL probe for each tube.

9.  Discard the prehyb soln, add 200 uL probe (1:200)/tube. Incubate 65˚C, O/N. Meanwhile, prepare the follow solns and preheat O/N at 65˚C:

a.  75% hyb + 25% 2X SSC

b.  50% hyb + 50% 2X SSC

c.  25% hyb + 75% 2X SSC

d.  100 % 2X SSC

Bill Campbell 1/20/03

In Situ Hybridization of ZF embryos 2 of 6

Day Two (estimated time ~ 4 hr)

1.  Wash 2X 30 min with 0.2X SSC 1 mL/tube at 65˚C. 0.2X SSC does not need to be pre-heated at 65˚C.

2.  Room temperature: (1mL/tube)

a.  75% 0.2X SSC + 25% PBST 5 min

b.  50% 0.2X SSC + 50% PBST 5 min

c.  25% 0.2X SSC + 75% PBST 5 min

d.  100% PBST 5 min

3.  Prepare 5% sheep serum in 2 mg/mL BSA in PBST: 500 uL/tube (one for blocking step, one for 2*Ab)
e.g. 1900 uL 2 mg/mL BSA in PBST + 100 uL 100% sheep serum = 2 mL (This is enough for 2 tubes).

4.  Block 500 uL/tube for 1-3 hours @ 4˚C (typically 2-3 hr). Store unused 5% SS that will be used for 2*Ab at 4˚C until it is ready to be used.

5.  Incubate in 1:2000 dilution of anti-Digoxigenin-Alkaline phosphatase conjugated Fab fragments antibody O/N at 4˚C. 1:2000 dilution or want 0.375 units/mL
e.g. 8 mL 5% SS + 4 uL anti-Digoxigenin-AP

Bill Campbell 1/20/03

In Situ Hybridization of ZF embryos 2 of 6

Day Three (estimated time ~ 4 hr)

1.  Wash at RT with 2 mg/mL BSA in PBST (stored at 4˚C between each step) 500 uL/tube (8 X 15 min)

2.  Can now stored at 4˚C in PBST O/N if no time for staining or continue.

3.  Prepare NTMT (all stock solns are autoclaved!): e.g. for 50 mL:
1M NaCl 5 mL
1M Tris, pH 9.5 5 mL
1M MgCl2 2.5 mL
Tween 20 50 mL
Sterile H2O 37.5 mL

4.  Equilibrate 3 X 5 min with NTMT, 1 mL/tube.

5.  Stain with BCIP/NBT in dark environment (cover with foil):
BCIP/NBT pre-mix is in 4˚C. Dilute 1:50 in NTMT e.g. 200 uL/10 mL NTMT.
Remove embryos to 12 wells plate with NTMT, then discard NTMT. Do 1 well at a time. It is OK if embryos are dry for a few seconds.
Add BCIP/NBT 1 mL/well.
Keep in dark (wrapped in foil) at RT. Stain for ~ 30 min to 2 hr or even longer if necessary. Check every half hour.

6.  Stop staining by washing 3X with PBST (3 short washes) and store at 4˚C wrapped in foil. Take pictures 1 week after staining.

Bill Campbell 1/20/03

In Situ Hybridization of ZF embryos 2 of 6

To Take Picture

- Wash with 100% methanol 3X 20 min or 1X 30 min according to Nishant/Tao 6.28.02

- Wash with PBST 3X quick wash.

- Keep in PBST at 4˚C, wrapped in foil, and take pictures. To take pictures, put some 3% methyl cellulose on glass decompression slide and put one embryo at a time with PBST onto slide

Probe recommendations:

-  can try 1:400 dilution of probe if 1:200 gives staining ubiquitously

-  usually include some 3”UTR so probe is more specific

Solution:

o  1X PBS = 2 L: 16g NaCl, 0.4g KCl, 2.88g Na2HPO4, 0.48g KH2PO4 - pH 7.4

o  PBST (1X PBS, 0.1% Tween 20)= 500 mL PBS + 0.5 mL Tween 20. Autoclave.

o  Proteinase K 1mg/mL in PBST at - 20˚C.

o  Proteinase K 100 mg Boehringer/Roche 745 723

o  Hybridization Buffer:
50% formamide Gibco BRL 500g 15515-026
5X SSC
5 mg/mL Torula (yeast) RNA Sigma 100g R-6625
50 ug/mL heparin Sigma H-7005
0.1% Tween 20
for 50 mL:
25 mL formamide
12.5 mL 20X SSC
250 mg torula (yeast) RNA
5 mL 500 ug/mL heparin
50 uL Tween 20
Bring up to 50 mL with Rnase/Dnase free H2O (~7.5 mL H2O).

o  4% Paraformaldehye for 500 mL:
20g PFA in 400 mL PBS. Heat to ~ 70˚C. Add a few drops of 5N NaOH to pH 7.4 and then add H2O to 500 mL final volume. Filter. Store at -20˚C.

o  PBST + 2 mg/mL BSA. For 50 mL:
50 mL PBST
100 mg BSA (Sigma A-8022 or A-2153)

o  Sheep Serum: Cat Sigma S2263

o  20X SSC
NaCl 175.3g
NaCitr 88.2g
H2O 800 mL
14 N HCl until pH = 7.0, then bring up to 1000 mL
Final [c] = 3 M NaCl, 0.3 M NaCitrate

o  Gibco Dnase/Rnase free H20 = Cat# 10977-015

o  2*Ab = Roch Enzo Anti-Digoxigenin-AP Fab fragments Cat# 1 093 274
(150 U, 200 uL; stored at 4˚C)

o  BCIP/NBT pre-mix = Roche Cat# 1 681 451 (8 mL)

o  Hybridization Oven = Robbins Scientific Model 2000 Micro Hybridization Incubator

Bill Campbell 1/20/03