Late labelled regions in relation to Q- and C-bands in chromosomes of Lilium longiflorum and L. pardalinum |
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Authors: | K Kongsuwan D R Smyth |
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Institution: | (1) Department of Genetics, Monash University, 3168 Clayton, Victoria, Australia;(2) Present address: Department of Biology, Khon Kaen University, Khon Kaen, Thailand |
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Abstract: | Root tips were pulse-labelled with tritiated thymidine. Late-labelled regions were mapped by quantitative autoradiography of metaphase chromosomes collected 11 h after the pulse for longiflorum (mean G2=14 h), and 13 h for pardalinum (mean G2=18 h). Late label in both species was preferentially located in sub-distal regions of the longer chromosome arms. Minimal labelling occurred in centromeric areas. — Some brightly Q-banded regions were late labelled, and some dull areas were not. However, late patterns were considerably more localised than bright Q-bands, and late regions were closely similar between species whereas Q-band patterns are not. Therefore bright Q-bands are apparently not consistently late replicating in Lilium, as they are in mammals, and they may therefore represent a different category of chromosomal substructure. — Centromeric C-bands and those at most nucleolar organisers were not late labelled. Only the more distal intercalary C-bands replicated late, and they were not significantly later than the chromatin surrounding them. |
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