Electron microscopic band-interband pattern of polytene chromosomes in Drosophila nasuta albomicans. 1. Salivary gland chromosome 2R.
The band-interband pattern of salivary gland chromosome 2R in Drosophila nasuta albomicans (division 53-83) was studied by light (LM) and electron microscopy (EM) using squash preparations and surface-spread polytene (SSP) chromosome preparations, respectively. LM and EM maps were compiled. Based on the digitized EM patterns of five homologous SSP chromosomes a computerized chromosome map was plotted. The EM pattern analysis showed a total number of 662 chromosome bands with an almost 98% increase compared with the LM analysis of squash preparations. The majority (about 92%) of interband lengths in SSP chromosome 2R ranged between 0.25 and 0.64 microns, which equal about 0.8-2.1 kb of totally extended DNA or 2.5-6.4 kb of DNA, if a DNA packing ratio of 0.1 microns/kb is assumed for the interbands of SSP chromosomes.
Singh
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OP
Institut für Genetik, Medizinische Fakultät, Ruhr-Universität Bochum, Federal Republic of Germany.
Kalisch
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D000818:Animals; D002871:Chromosome Banding / Q000379:methods*; D002874:Chromosome Mapping / Q000379:methods*; D002875:Chromosomes / Q000648:ultrastructure*; D004330:Drosophila / Q000166:cytology*; D008854:Microscopy, Electron; D012469:Salivary Glands / Q000166:cytology