High Resolution Imaging of Polytene Chromosomes

The exceptional organization of polytene chromosomes
has made fruit fly Drosophila melanogaster a premier
model organism for visualization of genes. A major
barrier to full exploitation of polytene chromosome
cytology has been the difficulty in producing good
chromosome preparations. A new, economical procedure
using high pressure and other modifications to
overcome this barrier is presented. Light microscopy
images of such slides compared to electron
microscopy images for the first time show similar or
superior detail. Results from typical staining
applications, including immunofluorescence and
fluorescence in situ hybridization are illustrated,
and optimized protocols for light and electron
microscopy presented. Also included are notes on the
general architecture of polytene chromosomes.
Improved chromosome images prompted collaborative
development of computer vision applications for
automated recognition and analysis of structural
patterns. These methods should be helpful for
researchers and students using the classical
polytene chromosome model as well as to all
scientists exploring wonderful possibilities that
computer vision opens to modern microscopy.