Nucleic Acid Metabolism of the Chromosomes in Relation to Gene Reproduction

A RELATION between the nucleic acid metabolism of the chromosomes and their reproduction is suggested by the localized appearance of thymonucleic acid in the chromosomes preparatory to their division1. The study of the nucleic acid metabolism of the salivary chromosomes and of the egg cytoplasm in certain variegated races of Drosophila melanogaster has now given evidence of a relation between nucleic acid metabolism and gene reproduction. The variegation in these races is due to an abnormality of gene reproduction, consequent upon chromosome rearrangements2 involving the ‘heterochromatic’ regions3. Cytologically, the variegation is correlated with deficiencies in the salivary gland chromosomes for the bands closest to the point of rearrangement, and with a darkening of the immediately adjacent remaining bands which suggests a change in their nucleic acid balance3.