CARD-FISH hybridization buffer

Recipe

Reagent		Amount to add
Blocking solution		2.0 mL
Dextran sulfate		2.0 g
H₂O		X mL (see below)
Formamide, molecular biology grade (70%)		(14 - X) mL (see below)
NaCl (5 M)		3.6 mL
SDS (sodium dodecyl sulfate; 20%, w/v)		20 μL
Tris-Cl (1 M, pH 8.0)		0.4 mL

Mix all reagents in a 50-mL tube. Heat to 40°C-60°C. Shake until the dextran sulfate dissolves completely. Aliquots of the buffer can be stored for several months at -20°C.

The stringency of the buffer can be varied as desired:
% formamide	mL formamide (14 - X)		mL water (X)
20	4		10
25	5		9
30	6		8
35	7		7
40	8		6
45	9		5
50	10		4
55	11		3
60	12		2
65	13		1
70	14		0