Molecular characterization of the purity of seven human chromosome-specific DNA libraries.
We have characterized at the molecular level seven chromosome-specific libraries constructed in phage lambda Charon 21A from flow-sorted human chromosomes. The purity of libraries prepared from chromosomes sorted from hamster X human cells was estimated by species-specific hybridization and ranged from 48% to 83% of clones containing human inserts. Among libraries of chromosomes from human cells, mass screenings were made for repetitive sequences and 20 clones from the #18 and #20 libraries were analyzed in detail. Ten to fifteen percent of all clones contain sequences which can be mapped; 80-100% of these derive from the intended chromosome of origin, demonstrating very high purity and a 35 X enrichment of chromosome-specific sequences over a total genomic library. The two libraries contain a high, though dissimilar, percent of repeat-containing clones; the #18 library has 55% repetitive clones and the #20 library 85%. This dissimilarity may be due to a difference in insert size distribution, since the #18 library has smaller inserts than the #20. This could be caused by variation in extent of digestion of insert DNA and/or differences in sequence organization between the two chromosomes. A method more sensitive than conventional plaque-lift screening was used to detect repetitive inserts; in this way nearly all repetitive clones could be eliminated before purification of their DNAs.
D000818:Animals; D002460:Cell Line; D002874:Chromosome Mapping; D002877:Chromosomes, Human / Q000648:ultrastructure*; D003001:Cloning, Molecular; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000235:genetics*; D005260:Female; D006801:Humans; D006822:Hybrid Cells / Q000166:cytology; D009693:Nucleic Acid Hybridization; D010053:Ovary
D004247:DNA