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Title: Double minute chromosomes in mouse methotrexate-resistant cells studied by atomic force microscopy

Double minute chromosomes (DMs) are acentric, autonomously replicating extra-chromosomes and frequently mediate gene amplification in tumor and drug resistant cells. Atomic force microscopy (AFM) is a powerful tool in microbiology. We used AFM to explore the ultrastructure of DMs in mouse fibroblasts 3T3R500. DMs in various phases of cell cycle were also studied in order to elucidate the mechanisms of their duplication and separation. Metaphase spread and induced premature condensed chromosomes (PCCs) were observed under the AFM. DMs were detected to be composed of two compact spheres linked by fibers. The fibers of DMs directly connected with metaphase chromosomes were observed. Many single-minutes and few DMs were detected in G1 PCCs, while more DMs were detected in S PCCs than in G1 PCCs. Besides, all of the DMs in G2 PCCs were coupled. Our present results suggested that DMs might divide into single-minutes during or before G1-phase, followed by duplication of the single-minutes in S-phase. Moreover, we introduced a new powerful tool to study DMs and got some ideal results.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [3] ;  [4]
  1. Laboratory of Medical Genetics, Harbin Medical University, Harbin 150086 (China)
  2. Laboratory of Medical Genetics, Harbin Medical University, Harbin 150086, (China)
  3. Precision Engineering Research Institute of Harbin Institute of Technology, Harbin 150001 (China)
  4. Laboratory of Medical Genetics, Harbin Medical University, Harbin 150086 (China) and Bio-pharmaceutical Key Laboratory of Heilongjiang Province, Harbin 150086 (China). E-mail: fusb@ems.hrbmu.edu.cn
Publication Date:
OSTI Identifier:
20854405
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemical and Biophysical Research Communications; Journal Volume: 346; Journal Issue: 4; Other Information: DOI: 10.1016/j.bbrc.2006.06.041; PII: S0006-291X(06)01323-4; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ATOMIC FORCE MICROSCOPY; CELL CYCLE; CHROMOSOMES; FIBERS; FIBROBLASTS; GENE AMPLIFICATION; METHOTREXATE; MICE; MITOSIS; NEOPLASMS