In situ hybridization to polytene chromosomes of drosophila melanogaster and other dipteran species

In situ hybridization of nucleotide sequence to Drosophila melanogaster interphase polytene chromosomes is a well established procedure. The method was initially developed using radioactively labeled probes by Pardue, who has recently published an extensive account of Drosophila polytene chromosomes and hybridization to these chromosomes (1 ). The original method was later adapted to allow the use of the more sensitive and safer nonradioactive labeling methods (2 ). The method has been used widely for gene mapping and identification of transposable element insertion sites. In situ hybridization to chromosomes has also been performed in cross-species studies within Diptera to give valuable evolutionary information, including conservation of linkage groups, and to identify homologous genes in related species (3 –5 ). In addition, there have been recent advances that extend this technique to salivary gland preparations from stored fixed specimens (6 ).