Do individual allocyclic chromosomes in metaphase reflect their interphase domains?
Individual S phase allocyclic chromosomes have been analyzed in Bloom syndrome lymphocytes, in cells with an r(9), and in hypotetraploid Ehrlich mouse ascites cells treated with 1-methyl-2-benzyl hydrazine. On the basis of the following observations, we conclude that such chromosomes more or less reflect their domains in interphase: (1) The S phase allocyclic chromosomes have the same structure as S phase prematurely condensed chromatin (PCC) in fused cells; in other words they form limited areas of chromatin dots; (2) the allocyclic chromosome is the only chromosome in a metaphase plate which synthesizes DNA simultaneously with interphase nuclei; (3) the size of the allocyclic chromosomes is related to the size of the corresponding metaphase chromosome; and (4) the S phase allocyclic chromosomes resemble closely the chromosome domains in interphase made visible with biotinylated human DNA. A variety of evidence shows that most allocyclic chromosomes are simply left behind in their cycle, which presumably is caused by a deletion or inactivation of a hypothetical coiling center situated on each chromosome arm.
Kuhn
E M
EM
Department of Obstetrics and Gynecology, University of Wisconsin Medical School, Mount Sinai Medical Center, Milwaukee 53201.
Therman
E
E
Buchler
D A
DA
D000818:Animals; D001816:Bloom Syndrome / Q000235:genetics* / Q000473:pathology; D002459:Cell Fusion; D002871:Chromosome Banding; D002877:Chromosomes, Human / Q000648:ultrastructure*; D002899:Chromosomes, Human, Pair 9; D006801:Humans; D007399:Interphase; D007621:Karyotyping; D008214:Lymphocytes / Q000648:ultrastructure; D008677:Metaphase; D051379:Mice