[Chromosome CPD(PI/DAPI)- and CMA/DAPI-banding patterns in Allium cepa L].
Chromosome banding patterns of Allium cepa L. were obtained by using fluorochrome combinations chromomycin A3 (CMA) + 4',6-diamidino-2-phenylindole (DAPI), DAPI + actinomycin D (AMD) and propidium iodide (PI) + DAPI. In A. cepa, telomeric heterochromatin displayed dull fluorescence after staining with DAPI and DAPI/AMD. After staining with the GC-specific CMA and AT-specific DAPI, the CMA-positive fluorescence of the NOR region and the telomeric bands of C-heterochromatin was observed. In combination with DAPI, PI, a dye with low AT/GC specificity, produced almost uniform fluorescence of chromosomal arms and heterochromatin, whereas the NOR-adjoining regions displayed bright fluorescence. Denaturation of chromosomal DNA (95 degrees C for 1-3 min) followed by renaturation in the 2 x SSC buffer (37 degrees C, 12 h) altered the chromosome fluorescence patterns: specific PI-positive bands appeared and the contrast of CMA-banding increased. Bright fluorescence of the NOR and adjoining regions was also observed in the case. Three-minute denaturation led also to a bright PI-positive fluorescence of telomeric heterochromatin. The denaturation of chromosomal DNA before staining results in changes of the DAPI fluorescence pattern and in the appearance of DAPI fluorescence in GR-rich NOP regions. The mechanisms underlying the effects of denaturation/renaturation procedures on chromosome banding patterns obtained with different fluorochromes are discussed.
Kim
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ES
Komarov Botanical Institute, Russian Academy of Sciences, St. Petersburg, 197376 Russia.
Punina
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EO
Rodionov
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AV
D014128:Chromomycin A3; D002871:Chromosome Banding / Q000379:methods*; D003609:Dactinomycin; D005456:Fluorescent Dyes; D006570:Heterochromatin; D007211:Indoles; D019697:Onions / Q000235:genetics*; D011419:Propidium
D005456:Fluorescent Dyes; D006570:Heterochromatin; D007211:Indoles; D003609:Dactinomycin; D011419:Propidium; C007293:DAPI; D014128:Chromomycin A3