The insertion of two 8-methyl-2′-deoxyguanosine residues in tetramolecular quadruplex structures: trying to orientate the strands

In this article, we report a structural study, based on NMR and CD spectroscopies, and molecular modelling of all possible d(TG3T) and d(TG4T) analogues containing two 8-methyl-2′-deoxyguanosine residues (M). Particularly, the potential ability of these modified residues to orientate the strands and then to affect the folding topology of tetramolecular quadruplex structures has been investigated. Oligodeoxynucleotides (ODNs) TMMGT (T12) and TMMGGT (F12) form parallel tetramolecular quadruplexes, characterized by an all-syn M-tetrad at the 5′-side stacked to all-anti M- and G-tetrads. ODNs TMGMT (T13) and TMGGMT (F14) form parallel tetramolecular quadruplexes, in which an all-anti G core is sandwiched between two all-syn M-tetrads at the 5′- and the 3′-side. Notably, the quadruplex formed by T13 corresponds to an unprecedented structure in which the syn residues exceed in number the anti ones. Conversely, ODN TGMGMT (F24) adopts a parallel arrangement in which all-anti G-tetrads alternate with all-syn M-tetrads. Most importantly, all data strongly suggest that ODN TMGMGT (F13) forms an unprecedented anti-parallel tetramolecular quadruplex in which G and M residues adopt anti and syn glycosidic conformations, respectively. This article opens up new understandings and perspectives about the intricate relationship between the quadruplex strands orientation and the glycosidic conformation of the residues

Intramolecular Folding in Human ILPR Fragment with Three C-Rich Repeats

Enrichment of four tandem repeats of guanine (G) rich and cytosine (C) rich sequences in functionally important regions of human genome forebodes the biological implications of four-stranded DNA structures, such as G-quadruplex and i-motif, that can form in these sequences. However, there have been few reports on the intramolecular formation of non-B DNA structures in less than four tandem repeats of G or C rich sequences. Here, using mechanical unfolding at the single-molecule level, electrophoretic mobility shift assay (EMSA), circular dichroism (CD), and ultraviolet (UV) spectroscopy, we report an intramolecularly folded non-B DNA structure in three tandem cytosine rich repeats, 5'-TGTC4ACAC4TGTC4ACA (ILPR-I3), in the human insulin linked polymorphic region (ILPR). The thermal denaturation analyses of the sequences with systematic C to T mutations have suggested that the structure is linchpinned by a stack of hemiprotonated cytosine pairs between two terminal C4 tracts. Mechanical unfolding and Br2 footprinting experiments on a mixture of the ILPR-I3 and a 5′-C4TGT fragment have further indicated that the structure serves as a building block for intermolecular i-motif formation. The existence of such a conformation under acidic or neutral pH complies with the strand-by-strand folding pathway of ILPR i-motif structures

Single strand DNA catenane synthesis using the formation of G-quadruplex structure.

DNA is a good material for constructing nanostructures such as DNA origami. One of the challenges in this field is constructing a topologically complex structure. Here, we synthesized a DNA catenane through the formation of a G-quadruplex structure. The formation of the DNA catenane was investigated by gel electrophoresis. Interestingly, the synthesized DNA catenane was destroyed by heat treatment. Because conventional methods to construct DNA catenane include enzymatic ligation or chemical reactions, DNA is cyclized by covalent bond connection and never destroyed by heat treatment. To our knowledge, this is the first report of the synthesis of DNA catenane without using covalent bonds. Our novel way of synthesizing DNA catenane may be of use in easily recoverable DNA topological labeling

グアニン四重鎖構造に対する化学的アプローチ、構造の設計・制御から生物学的関連性・ナノ構造まで

京都大学0048新制・課程博士博士(理学)甲第16655号理博第3767号新制||理||1545(附属図書館)29330京都大学大学院理学研究科化学専攻(主査)教授 杉山 弘, 教授 三木 邦夫, 教授 藤井 紀子学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDA

Studies on a New Virus (OMV) from Oncorhynchus masou. I, Characteristics and Pathogenicity

During 1978, we isolated a previously undescrived pathogenic virus from ovarian fluids of normal appearing adult landlocked masu salmon (Oncorhynchu masou) at the Otobe Salmon Hatchery, Hokkaido, Japan. Characteristics of the newly recognized virus conform to those of the Herpesvirus group, and the agent is provisionally named Oncorhynchus masou virus (OMV). The OMV has proven to be lethal for chum salmon (O. keta) by artificial immersion infection. Following immersion, 80 to 150-day-old fry began to die at 11 to 12 days later, and 35 to 60% of them succumbed in the ensuing 50 days. However, no death occurred among 240-day-old chum salmon that were similarly infected. Marked histopathologic changes were observed in liver sections. These were multiple foci of severe necrosis and syncytia formation. Further repeated experiments using other species of salmonids revealed that coho salmon (O. kisutch), kokanee salmon (O. nerka), and rainbow trout (Salmo gairdneri) were also susceptible to OMV, although some variations in susceptibility were noted. From the evidence thus far obtained, OMV is clearly a new pathogen of salmonids

Practice Scheduling and Composition in Judo

The purpose of the present study was to examine practice scheduling and composition in judo based upon motor learning theory. Practice scheduling and composition of Jiyu-renshu, Kakari-renshu, and Yakusokurenshu were analyzed from the case of the practice of A University judo team. A University judo team has a competitive level of participating in the national collegiate judo tournament. The viewpoints of analysis by motor learning theory were massed and distributed practice, random and blocked practice, whole and part practice, and variable and constant practice. Results demonstrated as follows. Massed and distributed practice, and Random and blocked practice were scheduled in Jiyu-renshu, Kakari-renshu, and Yakusoku-renshu. Whole practice was composed in Jiyu-renshu and Yakusoku-renshu by fractionation, while part practice was composed in Jiyu-renshu, Kakari-renshu, and Yakusoku-renshu. Whole practice was composed in Jiyu-renshu by simplification, while part practice was composed in Jiyu-renshu, Kakarirenshu, and Yakusoku-renshu. Whole practice was composed in Jiyu-renshu and Yakusoku-renshu by segmentation, while part practice was composed in Kakari-renshu, and Yakusoku-renshu. Variable and constant practice was composed in Jiyu-renshu, Kakari-renshu, and Yakusoku-renshu. Specific training methods were proposed for each practice