Description_x000D_ General description_x000D_ Sigma’s 123 bp DNA Step Ladder contains 35 dsDNA fragments from 123 to 4,182 bp. The fragments are 1 - 34 repeats of a 123 bp region of the rat prolactin gene. Ten ul of the marker should be diluted in gel loading buffer and then loaded in a single lane on an agarose or polyacrylamide gel._x000D_ Components_x000D_ Sigma’s 123 bp DNA Ladder is provided in a solution of 10 mM Tris-HCl (pH 7.5), 50 mM NaCl, and 0.1 mM EDTA._x000D_ Other Notes_x000D_ Contains 35 fragments, 123 - 4182 bp_x000D_ For optimal resolution, the recommended agarose gel concentration is 1.5%.