Central Loop Research Articles

Study of the flow around railway embankment of different heights with and without trains

The present work mainly focuses on the evolution of the airflow passing embankments of different heights, with and without trains. Using the delayed detached-eddy simulation (DDES) method, the effects on the velocity and acceleration of the airflow caused by the embankments’ upstream slope were studied using a set of embankments with different heights. The aerodynamic loads experienced by each car of the train, on both the windward and leeward rails, were calculated and the effects of different embankments examined. To distinguish how the geometry of embankments affected the flow patterns, distributions of streamline, velocity and the vortices formed around the head car and embankment are shown. The differences in pressure distribution on central loops of each car caused by the different embankment heights were analyzed at a yaw angle of 19.8°. Using the wind speed at 4 ​m above the actual rails and the reference at 10 ​m above the ground, the effect of wind speed on the aerodynamic forces and moments of the train, independent of the embankments’ height, can be obtained. This method has the potential to simplify the calculations needed to evaluate the safety of trains running on different embankment heights in strong wind environments.

Nucleolin Discriminates Drastically between Long-Loop and Short-Loop Quadruplexes.

We investigate herein the interaction between nucleolin (NCL) and a set of G4 sequences derived from the CEB25 human minisatellite that adopt a parallel topology while differing in the length of the central loop (from nine nucleotides to one nucleotide). It is revealed that NCL strongly binds to long-loop (five to nine nucleotides) G4 while interacting weakly with the shorter variants (loop with fewer than three nucleotides). Photo-cross-linking experiments using 5-bromo-2'-deoxyuridine (BrU)-modified sequences further confirmed the loop-length dependency, thereby indicating that the WT-CEB25-L191 (nine-nucleotide loop) is the best G4 substrate. Quantitative proteomic analysis (LC-MS/MS) of the product(s) obtained by photo-cross-linking NCL to this sequence enabled the identification of one contact site corresponding to a 15-amino acid fragment located in helix α2 of RNA binding domain 2 (RBD2), which sheds light on the role of this structural element in G4-loop recognition. Then, the ability of a panel of benchmark G4 ligands to prevent the NCL-G4 interaction was explored. It was found that only the most potent ligand PhenDC3 can inhibit NCL binding, thereby suggesting that the terminal guanine quartet is also a strong determinant of G4 recognition, putatively through interaction with the RGG domain. This study describes the molecular mechanism by which NCL recognizes G4-containing long loops and leads to the proposal of a model implying a concerted action of RBD2 and RGG domains to achieve specific G4 recognition via a dual loop-quartet interaction.

Innovative boat-towed transient electromagnetics — Investigation of the Furnas volcanic lake hydrothermal system, Azores

Water-covered areas may lead to gaps in surface electromagnetic surveys, causing reduced resolution and, as a consequence, increased uncertainty in derived subsurface models. We have evaluated a boat-towed floating central loop time-domain electromagnetic technique that mitigates this problem. It facilitates obtaining data with a spatial sampling density, which is rarely possible with standard instrumentation on land, and it only requires moderate logistical effort. A unique field study on a shallow volcanic lake demonstrated that this method is feasible with only a minor loss of accuracy when compared to anchored and land soundings. We found that the noise sources arising from the moving instrument and the boat engine can be neglected. The field survey was performed on the Lagoa das Furnas (São Miguel, Azores Islands, Portugal), which is located within an active volcanic area and is characterized by fumarolic fields and [Formula: see text] degassing. Thus, the associated hydrothermal system is expected to extend below the lake. However, the character, geometry, and extent of this system are unknown because of the lack of boreholes and geophysical studies. In total, 600 soundings, combining towed profiles with anchored and land-based soundings, were acquired with an aim of imaging the hydrothermal system beneath the lake down to 200 m. The results from all three types of measurements compare well and thus led to consistent 1D inversion models. The inversion results delineate a highly conductive, smectite-rich cap layer dipping below the lake away from the main fumarole zone. Near this zone, the extent of the conductor agrees well with an area of intense dispersed [Formula: see text] degassing, which appears to be controlled by at least two electrically distinctive fault zones in which the conductor is found at greater depths.

Dynamics of the 1:2:1 and 1:6:1 C-Myc G-Quadruplexes with the Drude Polarizable Force Field

G-quadruplexes (GQs) are noncanonical nucleic acid structures that form in guanine-rich sequences, importantly gene promoters and telomeres. The guanines within GQs arrange in square, planar tetrads through Hoogsteen hydrogen bonding. These tetrads stack on top of one another to make a highly ordered structure with an electronegative core. Coordinated cations are required to counteract the core's electronegativity and stabilize the GQ. GQs play important roles in gene expression and genomic stability and are functionally relevant in several human proto-oncogenes. One such proto-oncogene, c-myc, is linked to several human cancers such as Burkitt's lymphoma and multiples types of myeloma due to GQ formation within the promoter region of the gene acting as a gene silencer. As such, the c-myc GQ is a novel drug target for cancer therapy. Two solved GQ structures of interest in the c-myc promoter are the 1:2:1 and 1:6:1 GQs, named for differences in central loop length. Loop regions of GQs are known to affect topology, stability, and overall structure. Moreover, studies have shown nucleolin preferentially binds to the 1:6:1 GQ, prompting our present study on the dynamics of c-myc GQs. To analyze the importance of loop sequence on structural dynamics and gain information on this potential drug target, we performed molecular dynamics simulations utilizing the CHARMM36 non-polarizable and the Drude-2017 polarizable force fields (FF). The Drude FF accounts for electronic degrees of freedom via negatively charged particles placed on every heavy atom in the systems and has provided new insights on GQ dynamics and DNA-ion interactions. Our simulations of the 1:2:1 and 1:6:1 GQs demonstrate that polarization is important to model the stability, ion-ion, and ion-DNA interactions that underly GQ dynamics, emphasizing the importance of polarizable molecular dynamics in studying GQs.

Intracellularly Localized PIN-FORMED8 Promotes Lateral Root Emergence in Arabidopsis.

PIN-FORMED (PIN) auxin efflux carriers with a long central hydrophilic loop (long PINs) have been implicated in organogenesis. However, the role of short hydrophilic loop PINs (short PINs) in organogenesis is largely unknown. In this study, we investigated the role of a short PIN, PIN8, in lateral root (LR) development in Arabidopsis thaliana. The loss-of-function mutation in PIN8 significantly decreased LR density, mostly by affecting the emergence stage. PIN8 showed a sporadic expression pattern along the root vascular cells in the phloem, where the PIN8 protein predominantly localized to intracellular compartments. During LR primordium development, PIN8 was expressed at the late stage. Plasma membrane (PM)-localized long PINs suppressed LR formation when expressed in the PIN8 domain. Conversely, an auxin influx carrier, AUX1, restored the wild-type (WT) LR density when expressed in the PIN8 domain of the pin8 mutant root. Moreover, LR emergence was considerably inhibited when AXR2-1, the dominant negative form of Aux/IAA7, compromised auxin signaling in the PIN8 domain. Consistent with these observations, the expression of many genes implicated in late LR development was suppressed in the pin8 mutant compared with the WT. Our results suggest that the intracellularly localized PIN8 affects LR development most likely by modulating intracellular auxin translocation. Thus, the function of PIN8 is distinctive from that of PM-localized long PINs, where they generate local auxin gradients for organogenesis by conducting cell-to-cell auxin reflux.

A new insight into protein-protein interactions and the effect of conformational alterations in PCNA

The sliding clamp proteins are present in almost all forms of life and participate in various fundamental processes. Many of these proteins accommodate a conserved sequence that interacts with the hydrophobic groove on sliding clamps. The conserved sequence on proteins is known as the PCNA-interacting protein box, and the hydrophobic groove of PCNA contains regions of the inter-domain connecting loop, the central loop, and amino acids from the C-terminal tail of PCNA. We performed molecular dynamics simulation studies (1.0 μs) to analyze the structural changes at the atomic level in native, C22Y, and C81R mutant PCNA. Our study revealed significant changes at sites responsible for a functional trimeric form of PCNA. This study also unveils the dynamic behavior of IDCL, central loop, and the C-terminal tail, which are essential regions for protein binding with PCNA and also sheds light on the effect of mutations on binding with the Cdc9 peptide. The observation of Cdc9 peptide complexed with native and mutants (C22Y and C81R) structures possibly reveals the mechanism by which PCNA recruits different proteins required for various biological processes and also highlights the importance of dynamic behavior of key regions involved in PCNA protein-protein interactions.

First Results From Drone-Based Transient Electromagnetic Survey to Map and Detect Unexploded Ordnance

Unexploded ordnance (UXO), which causes many civilian casualties every year, has become a serious environmental problem. To deal with the problem, we have developed a new drone-based transient electromagnetic (TEM) system, which was designed for the UXO detection through very low altitude measurements. Drone-based TEM system uses the rotorcraft equipped with central loop TEM device to realize the UXO detection. The system was more safe and efficient than a ground-based TEM system in UXO detection. Compared with the airborne magnetic method or helicopter-borne TEM system, it has the advantages of low cost, flight safety, and so on. In this letter, the system characteristics are introduced in detail, providing the theoretical analysis of the system in UXO detection and verification of model data. Finally, through the UXO detection in the former weapon test base, the results show that the system is effective and successful in UXO detection.

A putative mechanism underlying secondary metabolite overproduction by Streptomyces strains with a 23S rRNA mutation conferring erythromycin resistance.

Mutations in rrn encoding ribosomal RNA (rRNA) and rRNA modification often confer resistance to ribosome-targeting antibiotics by altering the site of their interaction with the small (30S) and large (50S) subunits of the bacterial ribosome. The highly conserved central loop of domain V of 23S rRNA (nucleotides 2042-2628 in Escherichia coli; the exact position varies by species) of the 50S subunit, which is implicated in peptidyl transferase activity, is known to be important in macrolide interactions and resistance. In this study, we identified an A2302T mutation in the rrnA-23S rRNA gene and an A2281G mutation in the rrnC-23S rRNA gene that were responsible for resistance to erythromycin in the model actinomycete Streptomyces coelicolor A3(2) and its close relative Streptomyces lividans 66, respectively. Interestingly, genetic and phenotypic characterization of the erythromycin-resistant mutants indicated a possibility that under coexistence of the 23S rRNA mutation and mutations in other genes, S. coelicolor A3(2) and S. lividans 66 can produce abundant amounts of the pigmented antibiotics actinorhodin and undecylprodigiosin depending on the combinations of mutations. Herein, we report the unique phenomenon occurring by unexpected characteristics of the 23S rRNA mutations that can affect the emergence of additional mutations probably with an upswing in spontaneous mutations and enrichment in their variations in Streptomyces strains. Further, we discuss a putative mechanism underlying secondary metabolite overproduction by Streptomyces strains with a 23S rRNA mutation conferring erythromycin resistance.

Molecular cloning and characterization of serine protease inhibitor from food-borne nematode, Gnathostoma spinigerum

Gnathostoma spinigerum is a causative agent of human gnathostomiasis and infects people residing in endemic areas as well as travelers. Cutaneous and visceral larval migrants cause clinical manifestations, resulting in severe morbidity and mortality. To survive in hosts, these parasites have evolved various immune evasion mechanisms, including the release of regulatory molecules. Serine protease inhibitors (serpins) that are present in many parasitic helminths are proteins suspected of suppressing host serine protease-related digestion and immune responses. In this study, the serpin secreted by G. spinigerum (GsSerp) was characterized using bioinformatics and molecular biology techniques. The bioinformatics revealed that GsSerp contains 9 helices, 3 β-sheets, and a reactive central loop, which are conserved structures of the serpin superfamily. Recombinant GsSerp (rGsSerp) was expressed in E. coli (molecular weight, 39 kDa) and could inhibit chymotrypsin. Mouse polyclonal antibody against GsSerp could detect the native GsSerp in crude worm antigen but not the excretory–secretory product (ES) of infective-stage larva (aL3Gs). Moreover, the expression of GsSerp in the aL3Gs tissue was located in the hemolymph and intestinal tissue, indicating its role in parasite homeostasis. Our findings may help develop effective strategies for preventing and controlling gnathostomiasis.

Early diagnosis and surgical intervention untie the Gordian knot in newborns with colonic atresia: report of two cases and review of the literature.

Incidence of colonic atresia in living infants ranges from 1:5,000 to 1:60,000 (average 1:20,000). It constitutes 1.8 to 15% of all cases of atresia of the gastrointestinal tract. In 58.56-75% of all cases is right-sided. We aim, through the presentation of two cases of colonic atresia which we encountered and after systematic research of the current literature, at addressing three major issues: diagnostic approach, operative strategy and management of the prognostic parameters of the colonic atresia. The common parameter in these two cases was the early diagnosis, which played a significant role in the uncomplicated postoperative course. The first case was a type I sigmoid atresia. Contrast's escape during contrast enema examination due to accidental rupture of the distal part of the colon led to diagnosis. Side-to-side anastomosis, restoration of the rupture and a central loop sigmoidostomy were urgently performed. The second case was a type III atresia at the level of the ascending colon, which was early diagnosed via pregenital ultrasonography, in which colonic dilation was depicted. Restoration of the intestinal continuity early after birth was performed at a time. In conclusion, we believe that early diagnosis, selection of the appropriate operative strategy and prompt recognition of potential post-operative complications, especially rupture of the anastomosis, contribute to the optimization of the prognosis in patients with colonic atresia.

On the modelling of the switching mechanisms of a Coanda fluidic oscillator

A Coanda fluidic oscillator has been studied numerically and experimentally to understand the internal switching mechanism and to estimate the frequency of resulting pulsed jets. 2D numerical simulations were performed and the oscillator switching mechanism was unveiled. The results of the simulation confirmed that the pressure difference between the two control ports and the pressure difference between the two branches control the oscillation dynamics of the oscillator. A detailed function defining the pulsation frequency has been proposed, taking into account the forth and back velocities of the pressure wave in the feedback loops which are difficult to measure experimentally. A simplified form of the frequency function has thus been proposed. An experimental study was performed to validate the numerical results, using two oscillator prototypes having the same central part but different feedback loop configurations. The experimental results confirmed the frequency function proposed from the computational study. The effects of the inlet pressure and the length of feedback loops have been experimentally studied. It has been found that with a given feedback loop, the oscillation period initially decreases as the input pressure increases.

Application of Apparent Resistivity Ratio on the Interpretation of Small Central-loop TEM Survey in Areas of Conductive Overburden

Central-loop TEM sounding data are often interpretead with apparent resistivity as a function of depth. This can quickly give a qualitative understanding of the subsurface resistivity variation. However, when the resistivity contrast between anomalies and background is weak, especially when there is a conductive overburden, the apparent resistivity image is inadequate to quickly and visually identify local anomalies. As an alternative, the apparent resistivity ratios of each measured station to a reference station is proposed as a fast way to identify local conductive anomalies qualitatively. Modeling analyses are carried out on 1D layer model, 2D fault models, and a 3D prism model with conductive overburdens. The results show that the apparent resistivity ratio outperforms the apparent resistivity on intuitively reflecting the target anomaly. As an image enhancement technique, the apparent resistivity ratio performs data transformation on the original apparent resistivity data, normalizing the background response, and highlighting the anomaly. At last, the apparent resistivity ratio method is successfully applied on interpreting a small central-loop TEM survey on investigating karst structure beneath a freshwater river. It provides an alternative simple fast way for interpretation of central loop TEM measurements.

Rutile dielectric loop-gap resonator for X-band EPR spectroscopy of small aqueous samples.

The performance of a metallic microwave resonator that contains a dielectric depends on the separation between metallic and dielectric surfaces, which affects radio frequency currents, evanescent waves, and polarization charges. The problem has previously been discussed for an X-band TE011 cylindrical cavity resonator that contains an axial dielectric tube (Hyde and Mett, 2017). Here, a short rutile dielectric tube inserted into a loop-gap resonator (LGR) at X-band, which is called a dielectric LGR (dLGR), is considered. The theory is developed and experimental results are presented. It was found that a central sample loop surrounded by four "flux-return" loops (i.e., 5-loop-4-gap) is preferable to a 3-loop-2-gap configuration. For sufficiently small samples (less than 1 µL), a rutile dLGR is preferred relative to an LGR both at constant Λ (B1/Pl) and at constant incident power. Introduction of LGR technology to X-band EPR was a significant advance for site-directed spin labeling because of small sample size and high Λ. The rutile dLGR introduced in this work offers further extension to samples that can be as small as 50 nL when using typical EPR acquisition times.

Increased markers of cardiac vagal activity in leucine-rich repeat kinase 2-associated Parkinson's disease.

Cardiac autonomic dysfunction manifests as reduced heart rate variability (HRV) in idiopathic Parkinson's disease (PD), but no significant reduction has been found in PD patients who carry the LRRK2 mutation. Novel HRV features have not been investigated in these individuals. We aimed to assess cardiac autonomic modulation through standard and novel approaches to HRV analysis in individuals who carry the LRRK2 G2019S mutation. Short-term electrocardiograms were recorded in 14 LRRK2-associated PD patients, 25 LRRK2-non-manifesting carriers, 32 related non-carriers, 20 idiopathic PD patients, and 27 healthy controls. HRV measures were compared using regression modeling, controlling for age, sex, mean heart rate, and disease duration. Discriminant analysis highlighted the feature combination that best distinguished LRRK2-associated PD from controls. Beat-to-beat and global HRV measures were significantly increased in LRRK2-associated PD patients compared with controls (e.g., deceleration capacity of heart rate: p = 0.006) and idiopathic PD patients (e.g., 8th standardized moment of the interbeat interval distribution: p = 0.0003), respectively. LRRK2-associated PD patients also showed significantly increased irregularity of heart rate dynamics, as quantified by Rényi entropy, when compared with controls (p = 0.002) and idiopathic PD patients (p = 0.0004). Ordinal pattern statistics permitted the identification of LRRK2-associated PD individuals with 93% sensitivity and 93% specificity. Consistent results were found in a subgroup of LRRK2-non-manifesting carriers when compared with controls. Increased beat-to-beat HRV in LRRK2 G2019S mutation carriers compared with controls and idiopathic PD patients may indicate augmented cardiac autonomic cholinergic activity, suggesting early impairment of central vagal feedback loops in LRRK2-associated PD.

All-Atom Molecular Dynamics Simulations of Dimeric Lung Surfactant Protein B in Lipid Multilayers.

Although lung surfactant protein B (SP-B) is an essential protein that plays a crucial role in breathing, the details of its structure and mechanism are not well understood. SP-B forms covalent homodimers, and in this work we use all-atom molecular dynamics simulations to study dimeric SP-B’s structure and its behavior in promoting lipid structural transitions. Four initial system configurations were constructed based on current knowledge of SP-B’s structure and mechanism, and the protein maintained a helicity consistent with experiment in all systems. Several SP-B-induced lipid reorganization behaviors were observed, and regions of the protein particularly important for these activities included SP-B’s “central loop” and “hinge” regions. SP-B dimers with one subunit initially positioned in each of two adjacent bilayers appeared to promote close contact between two bilayers. When both subunits were initially positioned in the same bilayer, SP-B induced the formation of a defect in the bilayer, with water penetrating into the centre of the bilayer. Similarly, dimeric SP-B showed a propensity to interact with preformed interpores in the bilayer. SP-B dimers also promoted bilayer thinning and creasing. This work fleshes out the atomistic details of the dimeric SP-B structures and SP-B/lipid interactions that underlie SP-B’s essential functions.

From Synthetic Fragments of Endogenous Three-Finger Proteins to Potential Drugs.

The proteins of the Ly6 family have a three-finger folding as snake venom α-neurotoxins, targeting nicotinic acetylcholine receptors (nAChRs), and some of them, like mammalian secreted Ly6/uPAR protein (SLURP1) and membrane-attached Ly-6/neurotoxin (Lynx1), also interact with distinct nAChR subtypes. We believed that synthetic fragments of these endogenous proteins might open new ways for drug design because nAChRs are well-known targets for developing analgesics and drugs against neurodegenerative diseases. Since interaction with nAChRs was earlier shown for synthetic fragments of the α-neurotoxin central loop II, we synthesized a 15-membered fragment of human Lynx1, its form with two Cys residues added at the N- and C-termini and forming a disulfide, as well as similar forms of human SLURP1, SLURP2, and of Drosophila sleepless protein (SSS). The IC50 values measured in competition with radioiodinated α-bungarotoxin for binding to the membrane-bound Torpedo californica nAChR were 4.9 and 7.4 µM for Lynx1 and SSS fragments, but over 300 µM for SLURP1 or SLURP2 fragments. The affinity of these compounds for the α7 nAChR in the rat pituitary tumor-derived cell line GH4C1 was different: 13.1 and 147 µM for SSS and Lynx1 fragments, respectively. In competition for the ligand-binding domain of the α9 nAChR subunit, SSS and Lynx1 fragments had IC50 values of about 40 µM, which correlates with the value found for the latter with the rat α9α10 nAChR expressed in the Xenopus oocytes. Thus, the activity of these synthetic peptides against muscle-type and α9α10 nAChRs indicates that they may be useful in design of novel myorelaxants and analgesics.

Abstract 2756: A high-resolution G-quadruplex structure involved in cmyc oncogene regulation

Abstract Gene expression needs strict regulation in human cells to prevent tumorigenesis. Among other control mechanisms, guanine-rich sequences which are clustered in promoter regions of oncogenes can form four stranded nucleic acid structures, called G-quadruplexes (G4), and regulate their transcription. The cmyc protein is the most important cellular regulator for proliferation and is often overexpressed in cancer cells. The DNA G-quadruplex formed in the cmyc promoter is a transcriptional silencer element and stabilization of this G4 by small molecules suppresses cmyc transcription, making it a promising target for cancer therapy. High-resolution structures of the highly diverse G4s provide the opportunity to understand their molecular interactions with transcription factors and to design small molecules that specifically bind a particular G4 conformer. Characteristically, multiple G4s can be formed in gene promoter regions because their G-rich sequence generally contains more than the minimum of four G-stretches. While all reported cmyc G4s share the same core with parallel oriented strands, their overall shape is individualized by distinct combinations of varying flanking and loop motifs. In this study, we present a new high-resolution NMR structure of a G4 found to form in the cmyc promoter region. The determined cmyc G4 has a 1:6:1 loop-size arrangement and its conformation is largely defined by its long central loop of 6 nt. We show that this G4 structure is the preferred target of nucleolin protein in comparison to other G4s formed in the cmyc promoter, demonstrating how the polymorphism of a G-rich sequence can modulate the interaction with transcription factors and other regulators. Our NMR structure shows that, despite the length of the 6-nt loop motif and the associated increased flexibility, the folding converges well due to a base pairing between the central loop and the 5’-flanking. Thus, the long loop is pulled towards the 5’-end while analogous loop-flanking interactions are prevented at the opposite 3’-site. In conclusion, the presented new addition to the ensemble of possible cmyc promoter G4 conformations extends the folding landscape for this promoter region, in particular due to the long central loop. This may shed light on how proteins such as nucleolin can target specific G4 and shift the equilibrium of folding to fine-tune gene expression. Finally, this new structure is another promising target for cancer drug development. Citation Format: Jonathan Dickerhoff, Luying Chen, Guanhui Wu, Buket Onel, Clement Lin, Danzhou Yang. A high-resolution G-quadruplex structure involved in cmyc oncogene regulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2756.

Structure of the Human TRPML2 Ion Channel Extracytosolic/Lumenal Domain

TRPML2 is the least structurally characterized mammalian transient receptor potential mucolipin ion channel. The TRPML family hallmark is a large extracytosolic/lumenal domain (ELD) between transmembrane helices S1 and S2. We present crystal structures of the tetrameric human TRPML2 ELD at pH 6.5 (2.0Å) and 4.5 (2.95Å), corresponding to the pH values in recycling endosomes and lysosomes. Isothermal titration calorimetry shows Ca2+ binding to the highly acidic central pre-pore loop which is abrogated at low pH, in line with a pH-dependent channel regulation model. Small angle X-ray scattering confirms the ELD dimensions in solution. Changes in pH or Ca2+ concentration do not affect the protein's secondary structure, but can influence ELD oligomer integrity according to native mass spectrometry. Our data thus complete the set of high-resolution views of human TRPML channel ELDs and reveal some structural responses to the conditions the TRPML2 ELD encounters as the channel traffics through the endolysosomal system.

Erratum

Geophysical ProspectingVolume 67, Issue 7 p. 1977-1978 ErratumFree Access Erratum This article corrects the following: Analysing two-dimensional effects in central loop transient electromagnetic sounding data using a semi-synthetic tipper approach P. Yogeshwar, B. Tezkan, Volume 66Issue 2Geophysical Prospecting pages: 444-456 First Published online: May 5, 2017 First published: 17 May 2019 https://doi.org/10.1111/1365-2478.12807AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat In Yogeshwar and Tezkan (2018), the following error was published on page 452. Figure 8: The color bars are not filled in Fig. 8 a) and d). The correct figure with proper color bars is as follows: We apologize for this error. REFERENCE Yogeshwar P. and Tezkan B. 2018. Analysing two-dimensional effects in central loop transient electromagnetic sounding data using a semi-synthetic tipper approach. Geophysical Prospecting 66, 444– 456. Volume67, Issue7September 2019Pages 1977-1978 ReferencesRelatedInformation

Effects of Central Loop Length and Metal Ions on the Thermal Stability of G-Quadruplexes.

The central loop of G-quadruplex molecular beacons is a key element to sense target DNA or RNA sequences. In this study, circular dichroism spectroscopy (CD), thermal difference spectrum (TDS), non-denatured non-denaturing gel electrophoresis, and thermal stability analysis were used to investigate the effect of the central loop length on G-quadruplex features. Two series of G-quadruplexes, AG3TTAG3-(TTA)n-G3TTAG3T (n = 1–8) (named TTA series) and AG3TTTG3-(TTA)n-G3TTTG3T (n = 1–8) (named TTT series) were examined in K+ and Na+ solutions, respectively. CD and TDS spectral data indicated that TTA series adopted an antiparallel G-quadruplex structure in Na+ solution and a hybrid G-quadruplex structure in K+ solution respectively. TTT series exhibited a hybrid G-quadruplex structure in both Na+ and K+ solutions. UV melting curves indicated that the stability of G-quadruplex in both series was reduced by the elongation of central loop. Thermal stability analysis concluded that the G-quadruplex destabilization with long central loop is an entropy-driven process due to more flexible and longer central loops.