The Barr body is a looped X chromosome formed by telomere association.
We examined Barr bodies formed by isodicentric human X chromosomes in cultured human cells and in mouse-human hybrids using confocal microscopy and DNA probes for centromere and subtelomere regions. At interphase, the two ends of these chromosomes are only a micron apart, indicating that these inactive X chromosomes are in a nonlinear configuration. Additional studies of normal X chromosomes reveal the same telomere association for the inactive X but not for the active X chromosome. This nonlinear configuration is maintained during mitosis and in a murine environment.
Walker
C L
CL
Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Cargile
C B
CB
Floy
K M
KM
Delannoy
M
M
Migeon
B R
BR
D000818:Animals; D002460:Cell Line; D002503:Centromere / Q000648:ultrastructure; D015342:DNA Probes; D006801:Humans; D006822:Hybrid Cells / Q000166:cytology; D007399:Interphase; D051379:Mice; D008938:Mitosis; D009693:Nucleic Acid Hybridization; D014176:Protein Biosynthesis; D013194:Staining and Labeling; D014960:X Chromosome / Q000502:physiology / Q000648:ultrastructure*
D015342:DNA Probes