The estimation of polyteny in Drosophila salivary gland nuclei based on determination of desoxyribonucleic acid content

✍ Scribed by Kurnick, N. B. ;Herskowitz, Irwin H.

• Publisher: Wiley (John Wiley & Sons)
• Year: 1952
• Tongue: English
• Weight: 888 KB
• Volume: 39
• Category: Article
• ISSN: 0095-9898
• DOI: 10.1002/jcp.1030390208

✦ Synopsis

The dipteran salivary gland affords excellent material for the study of chromosome morphology, and provides a frequently used basis for general theories on the physical and chemical structure of genes and chromosomes. The giant chromosomes in these cells are generally regarded as polytene structures (D 'Angelo, '50 ; Metz, '41 ; Muller, '41 ; Painter, '41 ; Slizynski, '50). The degree of this polyteny is thought to be of the order of one to two thousand on the basis of the relative volumes of salivary gland nuclei and diploid nuclei of these species (Metz, '41 ; Muller, '41 ; Painter, '41). Since the implication that the chromonema is below the limit of resolution of the light microscope has important bearing on the interpretation of the morphological details of salivary chromosomes, it is desirable to have further evidence on the validity of this hypothesis. Such evidence may be obtained from the determination of the desoxyribonucleic acid (DNA) content of nuclei in view of the abundant evidence for the constancy of DNA per diploid cell in an individual (Boivin et al., '48 ; Kurnick and Mirsky, '47, unpublished ; Mirsky and Ris, '49 ; Swift, '50).