The electronic structure of GC and AT stacked dinucleotides, in two different forms of DNA (B and Z) is studied, using density functional theory. B3PW91 basis functional with 6-31G** basis set is applied to investigate molecular orbital distributions and energy levels of stacked dinucleotides in B-DNA and Z-DNA. It is demonstrated that the distribution of molecular orbitals in GC dinucleotide, in B form of DNA, is different from those in Z form. While HOMO in B-DNA is localized on guanine base, in Z-DNA, it is dragged away from the base and spreads over DNA backbone as well. Moreover, the energy levels of orbitals are also different. For AT stacked dinucleotide, it is shown that HOMO in B-DNA is localized on phosphate-sugar backbone whereas in Z-DNA it is localized on thymine base. It is also noted that energy levels of molecular orbitals being localized on DNA backbone, are 0.8 eV less than that of HOMO energy level, indicating the active participation of phosphate-sugar backbone of B- and Z-DNA in chemical reactions.

In this paper, the electrical transport of graphene and silicene nanostructures connected to two semi-infinite graphene and silicene electrodes have been investigated. In these structures, we created nanopores and passed the DNA molecule through the nanopore. Using the Green's Function method and Tight binding approximation, two types of systems with zigzag edges in graphene and silicene have been investigated. By connecting the nanoribbons to the metal electrodes, the created current passes from the nanopore and DNA, from the left to the right. This electric current flow increases the system's sensitivity to the organic DNA bases. We have introduced a new scheme for DNA sequencing.

Objective: Traditional methods for storing microbial DNA samples use the low-temperatures of 4oC, -20oC or -80oC. The DBC Card is a new method of storing microbial DNA at room temperature. This study evaluates the stability and determine the best storing method of Bacterial DNA on the DBC card.Methods: In this study, we used a pair of primers from the conserved domain of 16srRNA designed to identify Escherichia coli. Four different types of samples we prepared: i) bacterial suspension, ii) bacterial DNA extracted by the phenol-chloroform method, iii) bacterial lysate with lysis buffer and iv) bacterial DNA produced by the boiling method. All four samples were spotted on separate DBC cards and dried at room temperature. After periods of 3, 5 and 7 months, Escherichia coli samples were checked for DNA stability with two molecular techniques, conventional PCR with 1, 2 and 3 disks as a source of bacterial DNA (1 mm diameter) and Real-Time PCR.Results: Data showed that DNA stability was maintained after 7 months on a DBC disk, even using only one disk as a DNA source. The bacterial suspension was the best method for long-term storage of Escherichia coli DNA on the DBC Card.Conclusion: In traditional methods for storing sample, DNA quality reduces after freezing and thawing. However in the DBC method, DNA quality was maintained for a long duration. Advantages of the DBC method are easy sample handing, low cost, faster extraction, and reduced individual and environmental contamination.

Objective: DNA markers are one of the most important indicators for estimating Molecular weight of DNA samples, although it used in widespread medical and research laboratories. These markers are very divers and have been prepared in different manners and from different sources of DNA. But unfortunately, DNA markers haven't been made in our country and all of the markers that we use are made in a foreign country.The aim of this research is settings a suitable technology to produce this product in the lab.Material and Methods: With this aim, we used two different strains of lambda: c1857sam7 and EMBL3A both of which are lytic phages as a DNA source. These were grown in the suitable host, after plaque appearance on the bacterial lawn, suitable titer for phage collecting was determined. We also optimized plasmid purification method for extraction of pBR322, pUC18 and recombinant YZV plasmid DNA and designed fragments in the markers have been constructed by digesting these DNAs with variant enzymes. Results: In this study, we made seven DNA markers out of which four of them were made for the first time in the world (l/Hind III/BamH1, lHind III/EcoR1, Sam2, Sam1) and although foreign models of three of them exist but they were made in our country for the first time (l/Pst I, lHind III, pBR332/MspI).Conclusion: The' other goal of this study was to determining the best conditions for maintaining and preserving these markers in the lab which was successfully performed.