The structural peculiarities of condensed DNA micro- and nanoparticles formed in PCR |
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Authors: | Vasily N. Danilevich Vladimir V. Artemov Steven S. Smith Radmir V. Gainutdinov Andrey L. Mulyukin |
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Affiliation: | 1. Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Science, ul. Miklukho-Maklaya 16/10, Moscow, 117997 Russiadan@mx.ibch.ru;3. Shubnikov Institute of Crystallography, Russian Academy of Science, Leninsky Pr. 59, Moscow, 119333 Russia;4. City of Hope, 1500 E. Duarte Rd., Duarte, CA 91010 USA;5. Winogradsky Institute of Microbiology, Russian Academy of Science, Pr. 60-letiya Oktyabrya 7/2, Moscow, 117312 Russia |
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Abstract: | Studies of DNA condensation have opened new perspectives in biotechnology and medicine. DNA condensation induced by polyamines or trivalent metal ions in vitro at room temperature has been investigated in detail. Our recent studies have demonstrated Mg2+-mediated formation of DNA condensates during the PCR. In this study, we report the unique morphology and fine structure of PCR-generated condensed DNA particles using electron and atomic force microscopy. The principal morphologies of studied DNA condensates are 3D particles of micrometer dimensions, oval microdisks of nanometer thickness, filaments, and compact nano-sized particles. SEM examinations have revealed a new structural type of spherical and elliptical 3D microparticles formed by numerous definitely oriented microdisks and their segments. AFM revealed a granular structure of the microdisk surface and the smallest nano-sized disks and thinnest nanofibrils – that appear to be the primary products of DNA condensation during the PCR. We suggest that the formation of DNA nanofibrils and nanodisks in PCR occurs due to Mg2+ – mediated intermolecular (lateral) and intramolecular condensation of ssDNA. Aggregation of elementary nanodisks in the course of thermal PCR cycles, occurring both by magnesium cations and via complementary interactions, give a rise to large nano-sized aggregates and more complex microparticles. |
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Keywords: | inter- and intramolecular DNA condensation micro- and nanoparticles polymerase chain reaction electron microscopy atomic force microscopy |
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