A rapid chemical procedure for isolation and purification of chromosomal DNA from gram-negative bacilli.

A rapid and simple method for preparing chromosomal DNA from gram-negative bacilli is presented. It is based on the alkaline (NaOH 0.03 M) lysis of cell walls.

Free and membrane-bound polysomes from rat liver. 1. Improvements of subcellular fractionation.

Substantial improvements of cellular fractionation in ionic conditions allowing preservation of polysome structure and polysome-membrane interactions are reported. They consist primarily in minimizing the lysosomal content of fractions containing endoplasmic reticulum by isolating a lysosome-rich fraction with little loss (6%) of RNA. Endoplasmic reticulum membranes were recovered in high yield, mainly in association with mitochondria, the remainder being found in the post-lysosomal supernatant.

Free and membrane-bound polysomes from rat liver. 2. Recovery of large free and membrane-bound polysomes.

Techniques allowing the recovery of large free and membrane-bound polysomes in high yield are reported. Subcellular fractions were prepared from rat liver homogenates as described in the preceding paper. Purified microsomal membranes (obtained from the post-lysosomal supernatant) were adjusted to 50 mM Mg(CH3COO)2 and treated with 2% Triton X-100 and 0.

The use of metrizamide as a density-gradient medium in studies of rat-liver polysomes.

The behaviour of rat liver cytoplasmic ribonucleoproteins in metrizamide has been studied to determine whether the iodinated compound would offer any advantage over other centrifugation media for studies of polysome structure and function. 1. Polysomes had a density of 1.