Generation of an integrated karyotype of the honey bee (Apis mellifera L.) by banding pattern and fluorescent in situ hybridization

To enhance the scientific utility and practical application of the honey bee genome and assign the linkage groups to specific chromosomes, I identified chromosomes and characterized the karyotype of the sequenced strain DH4 of the honey bee. The primary analysis of the karyotype and ideogram construction was based on banding and Fluorescence In Situ Hybridization (FISH) for rDNA detection. FISH confirmed two locations for the NOR on telomeric regions of chromosomes 6 and 12 plus an additional less frequent signal on chromosome 1, all three of which were confirmed with silver staining (AgNO3). 4?6-diamidino-2phenylindole (DAPI), and CBanding methods were used to construct the primary ideograms that served as a basis to further identify the chromosomes and locate important structures. The primary map was compared with Giemsa banding, AgNO3-banding, Trypsin banding, and R-banding. The karyotype of the honey bee was established as two metacentric chromosomes (1 and 10), two submetacentric with ribosomal organizer (6 and 12), four submetacentric heterochromatic chromosomes (16, 15, 4 and 13), four euchromatic subtelocentric chromosomes (2, 8, 11 and 14) and four acrocentric chromosomes (3, 5, 7 and 9). In situ nick-translation banding methods were used to verify the heterochromatin distribution. The cytogenetic maps of the honey bee karyotype represented in the ideograms were subsequently used to place 35 mapped BACs (Solignac et. al. 2004) of Solignac?s BAC library. As the BACs hybridized to multiple sites, the mapping was based on strength and frequency of the signals. Location and position of the BACs was compared with those published in the different version of Map Viewer of the NCBI and BeeBase web sites. 10 BACs were confirmed with the last version of Map Viewer V4, 12 BACs were mapped based on high frequency and agreement with the earlier version of Map Viewer. 14 BACs were mapped as confirmed based on moderate frequency of the signal and agreement with the last version of MVV, most of these BACs hits as a secondary signal.