Cesium Chloride Protocol for Phage
Filter cesium solutions with 0.02µm filter. 
Mark top of first gradient layer with pen before adding next layers. 
Set up gradient as (from top to bottom): 1ml of 1.7 g/ml, mark top of layer 1ml of 1.5 g/ml, mark top of layer 1ml of 1.35 g/ml 8.5ml of 1.15 g/ml - this is phage concentrate.
Add CsCl to your sample.
Check balance of tubes.
Centrifuge at 22,000 rpm for 2 hours at 4°C, approximately 60-80,000xg.
Pierce tube at 1.7/1.5 g/ml interface.
Bevel up, and collect 1.5 mls (should include 1.5 g/ml step and 1.5 to 1.35 interface).  
Check with slides for virus particles, etc.
Use 20 µl from [viral] fraction and 500 µl from "upper" layers.
Store in fridge at 4°C until ready to extract.
Add 0.2 vol chloroform, mix and incubate 10 min. at room temperature. 
Spin at 4000 rpm in table Beckman for 10 minutes to separate phases.
Save and transfer top phase to new 15 ml tubes.
Add 10-15 µl DNase I (1 mg/ml in H2O) to phage sample (1.2-1.5ml). 
Incubate 15 minutes at 37°C.
Treat with RNase if RNA is to be extracted.
Inactivate for 15 minutes at 65°C.
Transfer all to new "oak ridge" tube for faster centrifugation later.
Add 0.1 volume 2 M TrisHCL (pH 8.5)/0.2 M EDTA. 
Add 100 µl 0.5 M EDTA per 10ml. 
Add 1 volume of formamide. 
Add 10 Fl glycogen Incubate at room temperature for 30 minutes.
Add 2 volumes of room temperature 100% ethanol.
Pellet in Sorvall (12,000 rpm for 20 minutes). 
Wash with 70% ethanol, two times.
Resuspend into 567 µl TE and continue with CTAB extraction.
Resuspend pellet in 567 µl TE.
Add 30 µl of 10% SDS and 3 µl of 20 µg/ml proteinase K. 
Mix.
Incubate 1 hour at 37°C - 56°C. 
Add 100 µl of 5 M NaCl and mix thoroughly.
Add 80 µl CTAB/NaCl solution.
Mix.
Incubate 10 minutes at 65°C.
Add equal volume of chloroform; mix.
Microcentrifuge for 2 minutes.
Transfer supernatant to separate tube.
Add equal volume of phenol/chloroform to the supernatant fraction; mix.
Microcentrifuge for 2 minutes.
Transfer supernatant to separate tube.
Add equal volume of chloroform to the supernatant fraction; mix.
Microcentrifuge for 2 minutes.
Transfer supernatant to separate tube.
Add 0.7 volume isopropanol to the supernatant fraction.
Mix gently until DNA precipitates.
Centrifuge 15 minutes in cold.
Wash with 70% ethanol.
Resuspend in 50 µl Sigma water Check O.D.
using the Nanodrop
