Characterization of four human YAC libraries for clone size, chimerism and X chromosome sequence representation.
Four collections of human X-specific YACs, derived from human cells containing supernumerary X chromosomes or from somatic cell hybrids containing only X human DNA were characterized. In each collection, 80-85% of YAC strains contained a single X YAC. Five thousand YACs from the various libraries were sized, and cocloning was assessed in subsets by the fraction of YAC insert-ends with non-X sequences. Cocloning was substantial, ranging up to 50% for different collections; and in agreement with previous indications, in all libraries the larger the YACs, the higher the level of cocloning. In libraries made from human-hamster hybrid cells, expected numbers of clones were recovered by STS-based screening; but unexpectedly, the two collections from cells with 4 or 5 X chromosomes yielded numbers of YACs corresponding to an apparent content of only about two X equivalents. Thus it is possible that the DNA of inactive X chromosomes is poorly cloned into YACs, speculatively perhaps because of its specialized chromatin structure.
Nagaraja
R
R
Center for Genetics in Medicine, Washington University School of Medicine, St Louis, MO 63110.
Kere
J
J
MacMillan
S
S
Masisi
M J
MJ
Johnson
D
D
Molini
B J
BJ
Halley
G R
GR
Wein
K
K
Trusgnich
M
M
Eble
B
B
D000818:Animals; D001483:Base Sequence; D002678:Chimera; D018244:Chromosomes, Artificial, Yeast; D003001:Cloning, Molecular; D006224:Cricetinae; D004247:DNA / Q000737:chemistry; D015723:Gene Library; D006801:Humans; D006822:Hybrid Cells; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D016133:Polymerase Chain Reaction; D014960:X Chromosome
D004247:DNA