A New Spreading Technique for Polytene Chromosomes and Its Efficiency for Autoradiography Including in situ Hybridization

Electron microscope analysis of the E polytene chromosome of Drosophila subobscura: region 70B to 72D

“…'cted region of the entire chromosome that is available for analysis in a single preparation.The analysis of adjacent chromosome bands depends upon well extended chromosome regions, which usually appear by chance. For these reasons, alternative techniques have been developed that provide a general view of almost the complete karyotype [10]. Nevertheless, the technique developed by Sorsa is the most conservative EM technique that allows the analysis of identified regions.…”

“…With respect to other species, only the polytene chromosomes of Drosophila hydei have been analyzed [3,4,9]. Recently, Drosophila subobscura has attracted some interest and a partial map of a region of the 0 chromosome by means of the surface spread technique [10] was published [9].…”

Ultrastructure of E1 + 2 + 9 + 12 inversion breakpoints in Drosophila subobscura

“…The use of electron microscopical techniques [3,12,19,33] has allowed detailed insight into the structural organization of polytene chromosomes. Several technical improvements have been carried out, for instance: a) to study the banding patterns and construct chromosome maps [4,5,13,14,20,22,23,[35][36][37]39] ; b) to investigate the informational content of precise sections related to transcriptional activity [2,[24][25][26]30] ; c) the ultrastructure of the insertion sites of mobile elements in the polytene chromosomes [27,28], as well as the formation and transpors of RNA-protein complexes [1,6,11,31,38].…”