Effects of Certain Chemical Treatments on the Morphology of Salivary Gland Chromosomes and Their Interpretation

Abstract

Chromosomes were treated with solns. of pH 14 to 1, which produced "lampbrush" chromosomes, of the type found in lower vertebrates. Probably alkali concentrates the nucleic acid which encrusts the chromonemata, thus making the latter visible as bristles. Chemically, flat aromatic molecules tend to associate with each other, plane upon plane into long threads; when nucleic acid is free to move, it remains free or attaches to a loosened polypeptide chain. Since condensation of nucleic acid always results in 2 longitudinal strings for each chromosome pair, it may mean that these strings have a primary independent existence in the untreated chromosome, or that there are simply 2 types of polypeptide chains together with their corresponding acids, and that there is no mixing of the 2 in the condensation process.