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A Polymerase – Tautomeric Model for Targeted Frameshift Mutations: Deletions Formation during Error-prone or SOS Replication of Double-stranded DNA Containing cis-syn Cyclobutane Thymine Dimers
Issue:
Volume 1, Issue 2, September 2015
Pages:
19-26
Received:
8 July 2015
Accepted:
16 July 2015
Published:
17 July 2015
Abstract: Now it is still unclear how frameshift mutations arise at cyclobutane pyrimidine dimers. The author develops polymerase – tautomeric model of ultraviolet mutagenesis. The model is described that is based on the formation of rare tautomeric bases in cis-syn cyclobutane thymine dimers. A mechanism was proposed for targeted deletions caused by cis-syn cyclobutane thymine dimers. Targeted deletions are frameshift mutations when one or several nucleotides are dropped out in a DNA site opposite to a lesion capable of stopping DNA synthesis. Ultraviolet irradiation may result in changes of tautomer states of DNA bases. Thymine molecule may form 5 rare tautomer forms. They are stable if these bases are part of cyclobutane dimers. Structural analysis indicates that opposite one type of cis-syn cyclobutane thymine dimers containing a single tautomeric base (TT2*, with the ‘*’ indicating a rare tautomeric base and the subscript referring to the particular conformation) it is impossible to insert any canonical DNA bases with the template bases with hydrogen bonds formation. Therefore it is proposed that under synthesis DNA containing cis-syn cyclobutane thymine dimers TT2* specialize or modified DNA polymerases will leave one nucleotide gaps opposite these cis-syn cyclobutane thymine dimers. Daughter DNA strand opposite cis-syn cyclobutane thymine dimers TT2* may fall out. If in opposite DNA strand the loop is formed, daughter strand becomes shorter. Some DNA nucleotides are lost. Targeted deletion is formed. According to the polymerase-tautomeric model of ultraviolet mutagenesis cis-syn cyclobutane thymine dimers wherein a thymine is in the canonical tautomeric forms do not result in mutations. Cis-syn cyclobutane thymine dimers wherein a thymine is in the rare tautomeric forms T1*, T4*, or T5* were shown to cause only targeted base substitution mutations. Cis-syn cyclobutane thymine dimers wherein a thymine is in the rare tautomeric form T2* may result in targeted frameshift mutations (targeted insertions and targeted deletions).
Abstract: Now it is still unclear how frameshift mutations arise at cyclobutane pyrimidine dimers. The author develops polymerase – tautomeric model of ultraviolet mutagenesis. The model is described that is based on the formation of rare tautomeric bases in cis-syn cyclobutane thymine dimers. A mechanism was proposed for targeted deletions caused by cis-syn...
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Memristor, a Nano-Scaled Element for the Computer Memory: A Mini-Review with Some New Results for an ac-Driven Memristor
Elena Zhitlukhina,
Mikhail Belogolovskii
Issue:
Volume 1, Issue 2, September 2015
Pages:
27-32
Received:
6 July 2015
Accepted:
19 July 2015
Published:
20 July 2015
Abstract: In this paper, we give a short look at the concept of memristive nano-technology, its history, and actual state-of-the-art. It is expected that together with advanced light-driven data transfer technology, computer operation will change dramatically by memristors, a new kind of the computer memory, which is becoming a sustaining hotspot in fields of physics and electronics. This entry aims to familiarize scientists working in the field of photonics with the phenomenon of resistive switching in ac-driven memristors. In addition to already published results, we present our original interpretation of resistance changes in heterostructures based on complex oxides with oxygen vacancies as the most moveable component under applied electric fields.
Abstract: In this paper, we give a short look at the concept of memristive nano-technology, its history, and actual state-of-the-art. It is expected that together with advanced light-driven data transfer technology, computer operation will change dramatically by memristors, a new kind of the computer memory, which is becoming a sustaining hotspot in fields o...
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Plasmon Resonances for Biospecific Interactions Sensing
Valeri Lozovski,
Margarita Razumova
Issue:
Volume 1, Issue 2, September 2015
Pages:
33-39
Received:
11 July 2015
Accepted:
24 July 2015
Published:
25 July 2015
Abstract: An implementation of plasmon resonances in nanocomposite thin films for biosensors is discussed. The effect is studied in the system of modified Au inclusions inside the Teflon matrix. The optical response of the nanocomposite thin film with inhomogeneous distribution of embedded coated Au spherical nanoparticles across the film thickness is analyzed. The absorption profiles are calculated in a case of light incidence normally to the film surface. Their dependences on volume fractions and spatial distributions of inclusion nanoparticles across the film thickness are discussed for some values of the film thickness. The obtained absorption profiles depending on the characteristics of the shell of nanoinclusions allow proposing the optical control method for the biospecific reactions at the surface of modified nanoinclusions.
Abstract: An implementation of plasmon resonances in nanocomposite thin films for biosensors is discussed. The effect is studied in the system of modified Au inclusions inside the Teflon matrix. The optical response of the nanocomposite thin film with inhomogeneous distribution of embedded coated Au spherical nanoparticles across the film thickness is analyz...
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Non-Conventional Standpoint on Spin Crossovers in the Organometallic Compounds of Iron Group
V. V. Shelest,
A. V. Hristov,
A. Yu. Prokhorov,
D. A. Chervinskii
Issue:
Volume 1, Issue 2, September 2015
Pages:
40-45
Received:
13 July 2015
Accepted:
24 July 2015
Published:
28 July 2015
Abstract: We have considered the spin crossover (SC) complex compounds containing spin-active metal ions of iron group, which can induce the spin transitions (ST) of high spin (HS) – low spin (LS) type under influence of temperature (TIST), pressure (PIST) or light (LIESST) from non-conventional point of view. We have analyzed the physical peculiarities of the studied ST systems observed in numerous papers for X ray, spectral, calorimetric and magnetic measurements. On this basis, we suppose that ST (for example, in bulk of SC compounds with TIST) can be considered as phase transitions (PT) of post-critical type (PCT)
Abstract: We have considered the spin crossover (SC) complex compounds containing spin-active metal ions of iron group, which can induce the spin transitions (ST) of high spin (HS) – low spin (LS) type under influence of temperature (TIST), pressure (PIST) or light (LIESST) from non-conventional point of view. We have analyzed the physical peculiarities of t...
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