[Micro- and nanoparticles of condensed DNA formed in a PCR with yeast genomic DNA as a template. Electron microscopy data].

It has been previously found that in a PCR with yeast genomic DNA as a template, microparticles of condensed DNA are formed in the presence of KlenTaq polymerase. In the present work, the study of these microparticles was continued using electron microscopy. It was shown that along with standard electron-dense microspheres, microspheres of a low electron density with a few thorns or without any thorns are formed. Various types of nanoparticles were detected in the samples: nanowires, dot-like electron-absorbing particles (nanodots), and compact nanoparticles (nanoscales) of different shape and size. It was found that increasing the number of PCR cycles above the optimum leads to an abrupt rise in the amount of nanoparticles in the PCR mixture. Suspensions of microparticles after quick (5 min) heating at 94 degrees C were examined. The partial melting of the microspheres in the heated samples was established: they lost part of the DNA and decreased in size; simultaneously, abundant clusters of nanowires appeared. The effect of nuclease S1 on the DNA of microspheres was studied. The molecular mechanisms of the formation of micro- and nanoparticles are discussed.