AFM images of G1-phase premature condensed chromosomes: Evidence for 30 nm changed to 50 nm chromatin fibers |
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Authors: | Yihui Fan Renfang Mao Jing Bai Xiaohong Zhang Songbin Fu |
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Affiliation: | a Laboratory of Medical Genetics, Harbin Medical University; Harbin 150081, China b Bio-pharmaceutical Key Laboratory of Heilongjiang Province, Harbin 150081, China c The Institute of Electrical and Electronic Engineering, Harbin University of Science and Technology, Harbin 150040, China d Key Laboratory for Medical Cell Biology Engineering of Heilongjiang Higher Education Institutions, Harbin 150081, China |
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Abstract: | To gain evidence for 30 nm changed to 50 nm chromatin fibers, we used atomic force microscopy (AFM) to study the ultrastructural organization of G1-phase premature condensed chromosomes (PCC). The surface of early G1-phase PCC is smooth and fibrous structures exist around the chromatids. The height of early G1-phase PCC is about 410 nm and the width is 1.07 ± 0.11 μm (n = 30). At late G1-phase, the surface becomes globular. The height of late G1-phase PCC is about 370 nm and the width is 845.04 ± 82.84 nm (n = 30). Phase image reveals that early G1-phase PCC is composed of 50 nm (48.91 ± 6.63 nm, n = 30) chromatin fibers and these 50 nm chromatin fibers tangle together, while late G1-phase PCC is composed of 30 nm (30.96 ± 4.07 nm, n = 30) chromatin fibers. At high magnification, fibers existing around the chromatids become clear in early G1-phase PCC. Chromatin fibers revealed by closer view of the end of chromatid are about 50 nm. In late G1-phase PCC, the surface presents globular structures. The shape of these globular structures is regular and the diameter is 118.96 ± 11.70 nm (n = 30). Our results clearly show that 30 nm chromatin fibers change to 50 nm chromatin fibers in G1-phase PCC and suggest that 50 nm chromatin fibers are the basic component of the mitotic chromosomes. |
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Keywords: | Premature condensed chromosomes (PCC) Atomic force microscopy (AFM) 50 nm Chromatin fibers 30 nm Chromatin fibers |
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