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Published November 21, 1990 | Published
Journal Article Open

Towards a physical map of the Drosophila melanogaster genome: mapping of cosmid clones within defined genomic divisions

Abstract

A physical map of the D. melanogaster genome is being constructed, in the form of overlapping cosmid clones that are assigned to specific poiytene chromosome sites. A master library of Ca . 20,000 cosmids is screened with probes that correspond to numbered chromosomal divisions (ca. 1% of the genome); these probes are prepared by microdissection and PCRamplification of individual chromosomes. The 120 to 250 cosmids selected by each probe are fingerprinted by Hinfl digestion and gel electrophoresis, and overlaps are detected by computer analysis of the fingerprints, permitting us to assemble sets of contiguous clones (contigs). Selected cosmids, both from contlgs and unattached, are then localized by in situ hybridization to polytene chromosomes. Crosshybrldlzation analysIs using end probes links some contigs, and hybridization to previously cloned genes relates the physical to the genetic map. This approach has been used to construct a physical map of the 3.8 megabase DNA in the three distal divisions of the × chromosome. The map is represented by 181 canonical cosmids, of which 108 clones in contigs and 32 unattached clones have been mapped Individually by in situ hybridization to chromosomes. Our current database of in situ hybridization results also includes the beginning of a physical map for the rest of the genome: 162 cosmids have been assigned by In situ hybridization to 129 chromosomal subdivisions elsewhere in the genome, representing 5 to 6 megabases of additional mapped DNA.

Additional Information

© 1990 IRL Press Limited. Creative Commons Attribution Non-Commercial licence (CC BY-NC). Received July 30, 1990; Revised and Accepted September 11, 1990. We are grateful to J. Sulston and A. Coulson for their assistance in launching this project, for making available the computer programs for fingerprint analysis, and for helpful advice. We thank H. Jaeckle, K. Wharton, and M. Monastirioti for participation in early phases of the project, P. Little for advice, G. Papagiannakis, V. Schoinas and V. Triantafyllou for technical assistance, M. Pittarokilis for assistance with computer analysis and all member of the IMBB Insect Group for helping 'toothpick' the master library. We are grateful to A. Gruner-Schlumberger for making possible the initiation of the project with seed funds from Foundation Schlumberger, and to the European Economic Community (Stimulation Action Programme) for continued financial support. We also acknowledge support from the Greek Secretariat General for Research and Technology, and from MRC and CRC grants to DG and RS, which enabled their participation in the earlier phases of this work.

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August 19, 2023
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