Berenil-induced undercondensation in human heterochromatin.
The aromatic diamidine berenil specifically inhibits the condensation of a subset of constitutive heterochromatin in human lymphocyte cultures. In the normal male chromosome complement, only the quinacrine-brilliant Y heterochromatin exhibits distinct undercondensation. The optimal culture conditions for inhibiting heterochromatin condensation are achieved when berenil is added at a final concentration of 150 micrograms/ml 24 h before cell harvest. Various examples of the use of berenil in the analysis of chromosome rearrangements involving quinacrine-brilliant heterochromatin are presented. A variant, giant-satellited chromosome 22 was found to respond to berenil treatment, although its enlarged and quinacrine-bright short-arm region did not contain Y heterochromatin. Southern blot analysis and chromosome in situ hybridization suggested that most chromosome 22 variants do not stem from Y; acrocentric translocations. The experimentally undercondensed Y heterochromatin is characterized by moderate C-band labeling, bright quinacrine fluorescence, and specific silver staining. At the ultrastructural level, undercondensation is associated with loosely packed, mutliply folded chromatin fibers with a diameter of approximately 250 A and organized probably as loops.
Haaf
T
T
Institut für Humangenetik, Universität Würzburg, Federal Republic of Germany.
Feichtinger
W
W
Guttenbach
M
M
Sanchez
L
L
Müller
C R
CR
Schmid
M
M
D000578:Amidines / Q000494:pharmacology*; D015139:Blotting, Southern; D002869:Chromosome Aberrations; D002875:Chromosomes / Q000648:ultrastructure; D004133:Diminazene / Q000031:analogs & derivatives / Q000494:pharmacology*; D006570:Heterochromatin / Q000187:drug effects*; D006801:Humans; D007621:Karyotyping; D008297:Male; D008677:Metaphase; D009693:Nucleic Acid Hybridization; D011110:Polymorphism, Genetic; D011797:Quinacrine Mustard; D013194:Staining and Labeling; D014998:Y Chromosome / Q000187:drug effects
D000578:Amidines; D006570:Heterochromatin; D011797:Quinacrine Mustard; C003915:diminazene aceturate; D004133:Diminazene