The meaning of DAPI bands observed after C-banding and FISH procedures.
Under specific technical conditions chromosome staining with 4',6-diamidino-2-phenylindole (DAPI) permits characterization of heterochromatic regions as AT-rich (DAPI(+)) or AT-poor (DAPI(-)), especially when the chromosomes are counterstained with chromomycin A(3) (CMA), which preferentially binds to GC-rich DNA. DAPI(+) bands also often have been observed after C-banding or FISH. In these cases, however, it is not clear whether only AT-rich regions stain positively with DAPI or other heterochromatins with different base compositions also are stained. We evaluated the meaning of DAPI bands observed after C-banding and FISH using three plant species bearing different types of heterochromatin: DAPI(+)/CMA(-), DAP(-)/CMA(+) and DAPI(0)/CMA(0) (neutral bands). Additional tests were performed using propidium iodide, a fluorochrome without preferential affinity for AT or GC. Our results indicate that AT-rich heterochromatin stains as DAPI(+) bands after C-banding or FISH, but other kinds of heterochromatin also may be stained by DAPI.
Barros e Silva
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AE
Laboratory of Plant Cytogenetics, Department of Botany, Federal University of Pernambuco, Recife, PE, Brazil.
Guerra
M
M
D020856:AT Rich Sequence; D014128:Chromomycin A3 / Q000737:chemistry; D002871:Chromosome Banding / Q000379:methods*; D005456:Fluorescent Dyes; D020862:GC Rich Sequence; D006570:Heterochromatin / Q000737:chemistry*; D017404:In Situ Hybridization, Fluorescence; D007211:Indoles / Q000737:chemistry*; D007364:Intercalating Agents; D010944:Plants / Q000235:genetics*; D011419:Propidium / Q000737:chemistry
D005456:Fluorescent Dyes; D006570:Heterochromatin; D007211:Indoles; D007364:Intercalating Agents; D011419:Propidium; C007293:DAPI; D014128:Chromomycin A3